0001737287-24-000021 | 10-K | XBRL Viewer | Allogene Therapeutics INC

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Description of Business and Summary of Significant Accounting Policies - Reconciliation of Restated Financial Statements - Statements of Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended			73 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2020
Statement of Stockholders' Equity [Abstract]
Net loss	$ (62,287)	$ (79,232)	$ (99,968)	$ (84,242)	$ (80,290)	$ (78,607)	$ (179,200)	$ (158,897)	$ (241,487)	$ (243,139)	$ (327,265)	$ (340,414)	$ (182,051)	$ (1,562,200)
Accumulated deficit	(1,476,455)	(1,414,168)	(1,334,936)	(1,137,693)	(1,053,451)	(973,161)	(1,414,168)	(1,053,451)	(1,476,455)	(1,137,693)	(1,562,233)	(1,234,968)	(894,554)	(1,562,233)
Total stockholders’ equity (deficit)	580,635	621,411	592,010	743,401	806,483	865,267	621,411	806,483	580,635	743,401	$ 512,233	666,882	925,200	$ 512,233	$ 1,013,457
As Previously Reported
Statement of Stockholders' Equity [Abstract]
Net loss	(61,315)	(77,989)	(98,704)	(83,148)	(74,787)	(79,850)	(176,693)	(154,637)	(238,008)	(237,785)		(332,632)	(257,005)
Accumulated deficit	(1,473,988)	(1,412,673)	(1,334,684)	(1,141,133)	(1,057,985)	(983,198)	(1,412,673)	(1,057,985)	(1,473,988)	(1,141,133)		(1,235,980)	(903,348)
Total stockholders’ equity (deficit)	583,102	622,906	592,262	739,961	801,949	855,230	622,906	801,949	583,102	739,961		665,870	916,406
Restatement Adjustment
Statement of Stockholders' Equity [Abstract]
Net loss	(972)	(1,243)	(1,264)	(1,094)	(5,503)	1,243	(2,507)	(4,260)	(3,479)	(5,354)		(7,782)	74,954
Accumulated deficit	(2,467)	(1,495)	(252)	3,440	4,534	10,037	(1,495)	4,534	(2,467)	3,440		1,012	8,794
Total stockholders’ equity (deficit)	$ (2,467)	$ (1,495)	$ (252)	$ 3,440	$ 4,534	$ 10,037	$ (1,495)	$ 4,534	$ (2,467)	$ 3,440		$ 1,012	$ 8,794

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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- Definition

Amount of accumulated undistributed earnings (deficit).

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- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details

Selected Quarterly Financial Data (Unaudited) - Balance Sheet (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 83,155	$ 69,246	$ 154,758	$ 109,931	$ 61,904	$ 74,357	$ 96,041	$ 84,514
Short-term investments	365,542	396,259	337,204	361,293	455,416	477,872	394,451	364,536
Prepaid expenses and other current assets	10,418	7,949	10,139	10,241	11,504	16,832	22,536	20,694
Total current assets	459,115	473,454	502,101	481,465	528,824	569,061	513,028	469,744
Long-term investments	0	32,170	52,586	42,788	59,151	85,108	195,637	284,093
Operating lease right-of-use asset	63,703	78,643	80,314	81,964	83,592	85,245	86,837	57,057
Property and equipment, net	99,478	102,826	106,386	109,849	112,839	114,442	117,216	120,200
Restricted cash	10,292	10,292	10,292	10,292	10,292	10,292	10,292	10,292
Other long-term assets	6,604	9,576	9,382	9,389	9,564	9,378	8,938	9,042
Equity method investments	3,645	6,450	11,946	14,381	17,317	20,951	23,673	27,663
Total assets	642,837	713,411	773,007	750,128	821,579	894,477	955,621	978,091
Current liabilities:
Accounts payable	5,897	6,205	10,229	14,688	13,890	11,045	9,713	8,708
Accrued and other current liabilities	31,096	31,195	44,263	44,624	39,743	36,938	34,360	27,763
Deferred revenue	86	86	86	86	95	99	104	147
Total current liabilities	37,079	37,486	54,578	59,398	53,728	48,082	44,177	36,618
Lease liability, noncurrent	88,346	90,102	91,821	93,514	95,122	96,706	98,232	69,035
Other long-term liabilities	5,179	5,188	5,197	5,205	5,847	6,288	6,729	7,171
Total liabilities	130,604	132,776	151,596	158,118	154,697	151,076	149,138	112,823
Stockholders’ equity:
Preferred stock	0	0	0	0	0	0	0	0
Common stock	169	168	167	146	144	144	144	143
Additional paid-in capital	2,075,252	2,059,333	2,039,263	1,932,734	1,911,632	1,893,908	1,871,262	1,847,534
Accumulated deficit	(1,562,233)	(1,476,455)	(1,414,168)	(1,334,936)	(1,234,968)	(1,137,693)	(1,053,451)	(973,161)	$ (894,554)
Accumulated other comprehensive loss	(955)	(2,411)	(3,851)	(5,934)	(9,926)	(12,958)	(11,472)	(9,249)
Total stockholders’ equity	512,233	580,635	621,411	592,010	666,882	743,401	806,483	865,267	925,200	$ 1,013,457
Total liabilities and stockholders’ equity	$ 642,837	$ 713,411	$ 773,007	$ 750,128	$ 821,579	$ 894,477	$ 955,621	$ 978,091
Preferred stock, par or stated value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0	0	0	0	0	0	0
Preferred stock, shares outstanding (in shares)	0	0	0	0	0	0	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	200,000,000
Common stock, shares issued (in shares)	168,642,238	168,175,221	167,133,664	145,740,333	144,438,304	144,031,588	143,723,171	143,569,902
Common stock, shares outstanding (in shares)	168,642,238	168,175,221	167,133,664	145,740,333	144,438,304	144,031,588	143,723,171	143,569,902
As Previously Reported
Current assets:
Cash and cash equivalents		$ 69,246	$ 154,758	$ 109,931		$ 74,357	$ 96,041	$ 84,514
Short-term investments		396,259	337,204	361,293		477,872	394,451	364,536
Prepaid expenses and other current assets		7,949	10,139	10,241		16,832	22,536	20,694
Total current assets		473,454	502,101	481,465		569,061	513,028	469,744
Long-term investments		32,170	52,586	42,788		85,108	195,637	284,093
Operating lease right-of-use asset		78,643	80,314	81,964		85,245	86,837	57,057
Property and equipment, net		102,826	106,386	109,849		114,442	117,216	120,200
Restricted cash		10,292	10,292	10,292		10,292	10,292	10,292
Other long-term assets		9,576	9,382	9,389		9,378	8,938	9,042
Equity method investments		5,365	9,910	11,124	$ 12,817	14,046	15,696	14,204
Total assets		712,326	770,971	746,871	817,079	887,572	947,644	964,632
Current liabilities:
Accounts payable		6,205	10,229	14,688		11,045	9,713	8,708
Accrued and other current liabilities		31,195	44,263	44,624		36,938	34,360	27,763
Deferred revenue		236	229	273	885	889	836	406
Total current liabilities		37,636	54,721	59,585	54,518	48,872	44,909	36,877
Lease liability, noncurrent		90,102	91,821	93,514		96,706	98,232	69,035
Other long-term liabilities		1,486	1,523	1,510	1,569	2,033	2,554	3,490
Total liabilities		129,224	148,065	154,609	151,209	147,611	145,695	109,402
Stockholders’ equity:
Preferred stock		0	0	0		0	0	0
Common stock		168	167	146		144	144	143
Additional paid-in capital		2,059,333	2,039,263	1,932,734		1,893,908	1,871,262	1,847,534
Accumulated deficit		(1,473,988)	(1,412,673)	(1,334,684)	(1,235,980)	(1,141,133)	(1,057,985)	(983,198)	(903,348)
Accumulated other comprehensive loss		(2,411)	(3,851)	(5,934)		(12,958)	(11,472)	(9,249)
Total stockholders’ equity		583,102	622,906	592,262	665,870	739,961	801,949	855,230	916,406
Total liabilities and stockholders’ equity		712,326	770,971	746,871	817,079	887,572	947,644	964,632
Restatement Adjustment
Current assets:
Cash and cash equivalents		0	0	0		0	0	0
Short-term investments		0	0	0		0	0	0
Prepaid expenses and other current assets		0	0	0		0	0	0
Total current assets		0	0	0		0	0	0
Long-term investments		0	0	0		0	0	0
Operating lease right-of-use asset		0	0	0		0	0	0
Property and equipment, net		0	0	0		0	0	0
Restricted cash		0	0	0		0	0	0
Other long-term assets		0	0	0		0	0	0
Equity method investments		1,085	2,036	3,257	4,500	6,905	7,977	13,459
Total assets		1,085	2,036	3,257	4,500	6,905	7,977	13,459
Current liabilities:
Accounts payable		0	0	0		0	0	0
Accrued and other current liabilities		0	0	0		0	0	0
Deferred revenue		(150)	(143)	(187)	(790)	(790)	(732)	(259)
Total current liabilities		(150)	(143)	(187)	(790)	(790)	(732)	(259)
Lease liability, noncurrent		0	0	0		0	0	0
Other long-term liabilities		3,702	3,674	3,695	4,278	4,255	4,175	3,681
Total liabilities		3,552	3,531	3,509	3,488	3,465	3,443	3,421
Stockholders’ equity:
Preferred stock		0	0	0		0	0	0
Common stock		0	0	0		0	0	0
Additional paid-in capital		0	0	0		0	0	0
Accumulated deficit		(2,467)	(1,495)	(252)	1,012	3,440	4,534	10,037	8,794
Accumulated other comprehensive loss		0	0	0		0	0	0
Total stockholders’ equity		(2,467)	(1,495)	(252)	1,012	3,440	4,534	10,037	$ 8,794
Total liabilities and stockholders’ equity		$ 1,085	$ 2,036	$ 3,257	$ 4,500	$ 6,905	$ 7,977	$ 13,459

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended			73 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Income Statement [Abstract]
Collaboration revenue - related party	$ 22	$ 22	$ 30	$ 27	$ 64	$ 39	$ 52	$ 103	$ 74	$ 130	$ 95	$ 156	$ 114,089
Operating expenses:
Research and development	45,977	62,038	80,238	63,641	57,171	60,156	142,276	117,327	188,253	180,968	242,914	256,387	220,176
General and administrative	17,041	18,524	18,884	18,897	19,509	19,897	37,408	39,406	54,449	58,303	71,673	79,305	74,105
Impairment of long-lived asset											13,245	0	0
Total operating expenses	63,018	80,562	99,122	82,538	76,680	80,053	179,684	156,733	242,702	239,271	327,832	335,692	294,281
Loss from operations	(62,996)	(80,540)	(99,092)	(82,511)	(76,616)	(80,014)	(179,632)	(156,630)	(242,628)	(239,141)	(327,737)	(335,536)	(180,192)
Other income (expense), net:
Interest and other income, net	6,205	3,778	2,059	1,002	315	492	5,837	807	12,042	1,809	18,307	4,566	1,714
Other expenses	(5,496)	(2,470)	(2,935)	(2,733)	(3,989)	915	(5,405)	(3,074)	(10,901)	(5,807)	(17,835)	(9,444)	(3,573)
Total other income (expense), net	709	1,308	(876)	(1,731)	(3,674)	1,407	432	(2,267)	1,141	(3,998)	472	(4,878)	(1,859)
Net loss	(62,287)	(79,232)	(99,968)	(84,242)	(80,290)	(78,607)	(179,200)	(158,897)	(241,487)	(243,139)	(327,265)	(340,414)	(182,051)	$ (1,562,200)
Other comprehensive income:
Net unrealized gain (loss) on available-for-sale investments	1,440	2,083	3,992	(1,486)	(2,223)	(6,682)	6,075	(8,905)	7,515	(10,391)	8,971	(7,359)	(2,835)
Net comprehensive loss	$ (60,847)	$ (77,149)	$ (95,976)	$ (85,728)	$ (82,513)	$ (85,289)	$ (173,125)	$ (167,802)	$ (233,972)	$ (253,530)	$ (318,294)	$ (347,773)	$ (184,886)
Net loss per share, basic (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)
Net loss per share, diluted (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)
Weighted-average number of shares used in computing net loss per share, basic (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386
Weighted-average number of shares used in computing net loss per share, diluted (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386

License and Collaboration Agreements	12 Months Ended
License and Collaboration Agreements	Dec. 31, 2023
Research and Development [Abstract]
License and Collaboration Agreements	License and Collaboration Agreements Asset Contribution Agreement with Pfizer In April 2018, the Company entered into an Asset Contribution Agreement (the Pfizer Agreement) with Pfizer pursuant to which the Company acquired certain assets, including certain contracts and intellectual property for the development and administration of chimeric antigen receptor (CAR) T cells for the treatment of cancer. The Company is required to make milestone payments upon successful completion of regulatory and sales milestones on a target-by-target basis for the targets including CD19 and B-cell maturation antigen (BCMA), covered by the Pfizer Agreement. The aggregate potential milestone payments upon successful completion of various regulatory milestones in the United States and the European Union are $30.0 million or $60.0 million, depending on the target, with aggregate potential regulatory and development milestones of up to $840.0 million, provided that the Company is not obligated to pay a milestone for regulatory approval in the European Union for an anti-CD19 allogeneic CAR T cell product, to the extent Servier has commercial rights to such territory. The aggregate potential milestone payments upon reaching certain annual net sales thresholds in North America, Europe, Asia, Australia and Oceania (the Territory) for a certain number of targets covered by the Pfizer Agreement are $325.0 million per target. The sales milestones in the foregoing sentence are payable on a country-by-country basis until the last to expire of any Pfizer Royalty Term, as described below, for any product in such country in the Territory. In October 2019, the Territory was expanded to all countries in the world. No milestone or royalty payments were made in the years ended December 31, 2023, 2022 and 2021. Pfizer is also eligible to receive, on a product-by-product and country-by-country basis, royalties in single-digit percentages on annual net sales for products covered by the Pfizer Agreement. The Company’s royalty obligation with respect to a given product in a given country begins upon the first sale of such product in such country and ends on the later of (i) expiration of the last claim of any applicable patent or (ii) 12 years from the first sale of such product in such country. Research Collaboration and License Agreement with Cellectis As part of the Pfizer Agreement, Pfizer assigned to the Company a Research Collaboration and License Agreement (the Original Cellectis Agreement) with Cellectis S.A. (Cellectis). On March 8, 2019, the Company entered into a License Agreement (the Cellectis Agreement) with Cellectis. In connection with the execution of the Cellectis Agreement, on March 8, 2019, the Company and Cellectis also entered into a letter agreement (the Letter Agreement), pursuant to which the Company and Cellectis agreed to terminate the Original Cellectis Agreement. The Original Cellectis Agreement included a research collaboration to conduct discovery and pre-clinical development activities to generate CAR T cells directed at targets selected by each party, which was completed in June 2018. Pursuant to the Cellectis Agreement, Cellectis granted to the Company an exclusive, worldwide, royalty-bearing license, on a target-by-target basis, with sublicensing rights under certain conditions, under certain of Cellectis’ intellectual property, including its TALEN and electroporation technology, to make, use, sell, import, and otherwise exploit and commercialize CAR T products directed at certain targets, including BCMA, CD70, Claudin 18.2, DLL3 and FLT3 (the Allogene Targets), for human oncologic therapeutic, diagnostic, prophylactic and prognostic purposes. In addition, certain Cellectis intellectual property rights granted by Cellectis to the Company and to Servier pursuant to the Exclusive License and Collaboration Agreement by and between Servier and Pfizer, dated October 30, 2016, which Pfizer assigned to the Company in April 2018, will survive the termination of the Original Cellectis Agreement. Pursuant to the Cellectis Agreement, the Company granted Cellectis a non-exclusive, worldwide, royalty-free, perpetual and irrevocable license, with sublicensing rights under certain conditions, under certain of the Company's intellectual property, to make, use, sell, import and otherwise commercialize CAR T products directed at certain targets (the Cellectis Targets). The Cellectis Agreement provides for development and sales milestone payments by the Company of up to $185.0 million per product that is directed against an Allogene Target, with aggregate potential development and sales milestone payments totaling up to $2.8 billion. Cellectis is also eligible to receive tiered royalties on annual worldwide net sales of any products that are commercialized by the Company that contain or incorporate, are made using or are claimed or covered by, Cellectis intellectual property licensed to the Company under the Cellectis Agreement (the Allogene Products), at rates in the high single-digit percentages. Such royalties may be reduced, on a licensed product-by-licensed product and country-by-country basis, for generic entry and for payments due under licenses of third-party patents. Pursuant to the Cellectis Agreement, and subject to certain exceptions, the Company is required to indemnify Cellectis against all thirdparty claims related to the development, manufacturing, commercialization or use of any Allogene Product or arising out of the Company’s material breach of the representations, warranties or covenants set forth in the Cellectis Agreement, and Cellectis is required, subject to certain exceptions, to indemnify the Company against all third party claims related to the development, manufacturing, commercialization or use of CAR T products directed at Cellectis Targets or arising out of Cellectis’ material breach of the representations, warranties or covenants set forth in the Cellectis Agreement. The royalties are payable, on a licensed product-by-licensed product and country-by-country basis, until the later of (i) the expiration of the last to expire of the licensed patents covering such product; (ii) the loss of regulatory exclusivity afforded such product in such country, and (iii) the tenth anniversary of the date of the first commercial sale of such product in such country; however, in no event shall such royalties be payable, with respect to a particular licensed product, past the twentieth anniversary of the first commercial sale for such product. Depending on the Cellectis Target, the Company has a right of first refusal or right of first negotiation to purchase or license from Cellectis rights to develop and commercialize products against such Cellectis Targets. Under the Cellectis Agreement, the Company has certain diligence obligations to progress the development of CAR T product candidates and to commercialize one CAR T product per Allogene Target in one major market country where the Company has received regulatory approval. If the Company materially breaches any of its diligence obligations and fails to cure within 90 days, then with respect to certain targets, such target will cease to be an Allogene Target and instead will become a Cellectis Target. Unless earlier terminated in accordance with its terms, the Cellectis Agreement will expire on a product-by-product and country-by-country basis, upon expiration of all royalty payment obligations with respect to such licensed product in such country. The Company has the right to terminate the Cellectis Agreement at will upon 60 days’ prior written notice, either in its entirety or on a target-by-target basis. Either party may terminate the Cellectis Agreement, in its entirety or on a target-by-target basis, upon 90 days’ prior written notice in the event of the other party’s uncured material breach. The Cellectis Agreement may also be terminated by the Company upon written notice at any time in the event that Cellectis becomes bankrupt or insolvent or upon written notice within 60 days of a consummation of a change of control of Cellectis. All costs the Company incurred in connection with this agreement were recognized as research and development expenses in the consolidated statement of operations. For the years ended December 31, 2023 and 2022, zero clinical development milestones were achieved. For the year ended December 31, 2021, $10.0 million of costs were incurred related to the achievement of clinical development milestones under this agreement. License and Collaboration Agreement with Servier As part of the Pfizer Agreement, Pfizer assigned to the Company an Exclusive License and Collaboration Agreement (the Servier Agreement), with Les Laboratoires Servier SAS and Institut de Recherches Internationales Servier SAS (collectively, Servier) to develop, manufacture and commercialize certain allogeneic anti-CD19 CAR T cell product candidates, including UCART19, in the United States with the option to obtain the rights over additional anti-CD19 product candidates and for allogeneic CAR T cell product candidates directed against one additional target. In October 2019, the Company agreed to waive its rights to the one additional target. Under the Servier Agreement, the Company has an exclusive license to develop, manufacture and commercialize UCART19, ALLO-501 and ALLO-501A in the field of anti-tumor adoptive immunotherapy in the United States, with an exclusive option to obtain the same rights for additional product candidates in the United States and, if Servier does not elect to pursue development or commercialization of those product candidates in certain markets outside of the United States pursuant to its license, outside of the United States as well. The Company is not required to make any additional payments to Servier to exercise an option. If the Company opts-in to another product candidate, Servier has the right to obtain rights to such product candidate outside the United States and to share development costs for such product candidate. Under the Servier Agreement, the Company is required to use commercially reasonable efforts to develop and obtain marketing approval in the United States in the field of anti-tumor adoptive immunotherapy for at least one product directed against CD19, and Servier is required to use commercially reasonable efforts to develop and obtain marketing approval in the European Union, and one other country in a group of specified countries outside of the European Union and the United States, in the field of anti-tumor adoptive immunotherapy for at least one allogeneic adaptive T cell product directed against a certain Company-selected target. For product candidates that the Company is co-developing with Servier, including UCART19, ALLO-501 and ALLO-501A, the Company is responsible for 60% of the specified development costs and Servier is responsible for the remaining 40% of the specified development costs under the applicable global research and development plan. Subject to certain restrictions, each party has the right to conduct activities that are specific to its territory outside the global research and development plan at such party’s sole expense. In addition, each party is solely responsible for commercialization activities in its territory at such party’s sole expense. The Company is required to make milestone payments to Servier upon successful completion of regulatory and sales milestones. The Servier Agreement provides for aggregate potential payments by the Company to Servier of up to $137.5 million upon successful completion of various regulatory milestones, and aggregate potential payments by the Company to Servier of up to $78.0 million upon successful completion of various sales milestones. Similarly, Servier is required to make milestone payments upon successful completion of regulatory and sales milestones for products directed at the Allogene-target covered by the Servier Agreement that achieves such milestones. The total potential payments that Servier is obligated to make to the Company under the Servier Agreement upon successful completion of regulatory and sales milestones are $42.0 million and €70.5 million ($77.8 million), respectively. The foregoing milestones are subject to certain adjustments if the Company obtains rights for certain products outside of the United States upon Servier’s election not to pursue such rights. Each party is also eligible to receive tiered royalties on annual net sales in countries within the paying party’s respective territory of any licensed products that are commercialized by such party that are directed at the targets licensed by such party under the Servier Agreement. The royalty rates are in a range from the low tens to the high teen percentages. Such royalties may be reduced for interchangeable drug entry, expiration of patent rights and amounts paid pursuant to licenses of third-party patents. The royalty obligation for each party with respect to a given licensed product in a given country in each party’s respective territory (the Servier Royalty Term) begins upon the first commercial sale of such product in such country and ends after a defined number of years. Unless earlier terminated in accordance with the Servier Agreement, the Servier Agreement will continue, on a licensed product-by-licensed product and country-by-country basis, until the Servier Royalty Term with respect to the sale of such licensed product in such country expires. On September 15, 2022, Servier sent a notice of discontinuation (Discontinuation) of its involvement in the development of all licensed products directed against CD19, including UCART19, ALLO-501 and ALLO-501A (collectively, CD19 Products), pursuant to the Servier Agreement. Servier’s Discontinuation provides the Company with the right to elect a license to the CD19 Products outside of the United States (Ex-US Option) and does not otherwise affect the Company's current exclusive license for the development and commercialization of CD19 Products in the United States. However, Servier has disputed the implications of the Discontinuation, namely whether development cost contributions continue and the timeframe during which the Company has the right to elect a license to CD19 Products outside of the United States. In December 2022, Servier sent the Company a notice for material breach due to the Company's purported refusal to allow an audit of certain manufacturing costs under the cost share arrangement. While the Company does not believe Servier has such an audit right, the Company submitted to a review of the Company's manufacturing costs of CD19 Products to recover outstanding manufacturing costs owed by Servier to the Company. In July 2023, Servier sent the Company a second notice for material breach alleging that the Company overcharged Servier based on Servier and its accounting firm’s review of costs eligible for cost-sharing under the Servier Agreement. The Company disagrees with the material breach allegations and the Company is disputing such allegations. Absent a resolution between the parties, disputed matters may be resolved in arbitration as specified in the Servier Agreement. For the years ended December 31, 2023, 2022 and 2021, the Company recorded zero , $19.9 million, and $17.1 million, respectively, of net cost recoveries under the cost-sharing terms of the Servier Agreement as a reduction to research and development expenses. As of December 31, 2023 and 2022, amounts due from Servier of zero and $1.5 million, respectively, were recorded in other current assets in the accompanying consolidated balance sheets. For the year ended December 31, 2022, $8.0 million in costs were incurred related to the achievement of a clinical development milestone under the Servier Agreement. Zero clinical development milestones were achieved for the years ended December 31, 2023 and 2021. Research Collaboration and License Agreement with Notch Therapeutics On November 1, 2019, the Company entered into a Collaboration and License Agreement (the Notch Agreement) with Notch Therapeutics Inc. (Notch), pursuant to which Notch granted to Allogene an exclusive, worldwide, royalty-bearing, sublicensable license under certain of Notch’s intellectual property to develop, make, use, sell, import, and otherwise commercialize therapeutic gene-edited T cell and/or natural killer (NK) cell products from induced pluripotent stem cells directed at certain CAR targets for initial application in non-Hodgkin lymphoma, acute lymphoblastic leukemia and multiple myeloma. In addition, Notch has granted Allogene an option to add certain specified targets to its exclusive license in exchange for an agreed per-target option fee. The Notch Agreement includes a research collaboration to conduct research and pre-clinical development activities to generate engineered cells directed to Allogene’s exclusive targets, which will be conducted in accordance with an agreed research plan and budget under the oversight of a joint development committee. Allogene will reimburse Notch’s costs incurred in accordance with such plan and budget. The term of the research collaboration will expire upon the earlier of (i) the fifth anniversary of the date of the Notch Agreement, (ii) at Allogene’s election, following the joint development committee’s determination that for each exclusive target, Notch has met certain success criteria, or (iii) the joint development committee’s determination that the research collaboration cannot be reasonably pursued against any exclusive target due to technical infeasibility or safety issues. In connection with the execution of the Notch Agreement, Allogene made an upfront payment to Notch of $10.0 million in return for a license to access Notch's technology in order to conduct research pursuant to the Notch Agreement. The Company recognized a research and development expense of $10 million during the year ended December 31, 2019 as the license had no foreseeable alternative future use. In addition, Allogene made a $5.0 million investment in Notch’s series seed convertible preferred stock, resulting in Allogene having a 25% ownership interest in Notch’s outstanding capital stock on a fully diluted basis immediately following the investment. In connection with this investment, an Allogene representative serves on the Notch Board of Directors. In February 2021, the Company made an additional $15.9 million investment in Notch's Series A preferred stock. In October 2021, the Company made an additional $1.8 million investment in Notch's common stock. Immediately following this transaction, the Company's share in Notch was 23.0% on a voting interest basis. The Company did not have a controlling interest in Notch as of December 31, 2023, and continued to account for its investment in Notch as an equity method investment. Under the Notch Agreement, Notch will be eligible to receive up to $7.3 million upon achieving certain agreed research milestones, up to $4.0 million per exclusive target upon achieving certain pre-clinical development milestones, and up to $283.0 million per exclusive target and cell type (i.e., T cell or NK cell) upon achieving certain clinical, regulatory and commercial milestones. Notch is also entitled to receive tiered royalties in the mid to high single digit range on Allogene’s sales of licensed products, subject to certain reductions, for a term, on a country-by-country and product-by-product basis, commencing on first commercial sale of such product in such country and continuing until the latest of (i) the date upon which there is no valid claim of the licensed patents in such country of sale that covers such product, (ii) the expiration of applicable data or other regulatory exclusivity in such country of sale or (iii) a defined period from the first commercial sale of such product in such country. The terms of the Notch Agreement will continue on a product-by-product and country-by-country basis until Allogene’s payment obligations with respect to such product in such country have expired. Following such expiration, Allogene’s license with respect to such product and country shall be perpetual, irrevocable, fully paid up and royalty-free. Allogene may terminate the Collaboration Agreement in whole or on a product-by-product basis upon ninety days’ prior written notice to Notch. Either party may also terminate the Collaboration Agreement with written notice upon material breach by the other party, if such breach has not been cured within a defined period of receiving such notice, or in the event of the other party’s insolvency. For the years ended December 31, 2023, 2022, and 2021, the Company recorded $1.8 million, $3.8 million, and $4.3 million, respectively, in collaboration costs as research and development expenses. For the year ended December 31, 2021, $0.3 million in costs were incurred related to the achievement of a research milestone under this agreement. Zero milestones were achieved for the years ended December 31, 2023 and 2022. For the year ended December 31, 2023, the Company recorded $3.0 million in other expenses as impairment loss on its equity method investment in Notch. Zero impairment loss was recorded for the years ended December 31, 2022 and 2021. Strategic Alliance with The University of Texas MD Anderson Cancer Center On October 6, 2020, the Company entered into a strategic five-year collaboration agreement with The University of Texas MD Anderson Cancer Center (MD Anderson) for the preclinical and clinical investigation of allogeneic CAR T cell product candidates. The Company and MD Anderson are collaborating on the design and conduct of preclinical and clinical studies with oversight from a joint steering committee. Under the terms of the agreement, the Company has committed up to $15.0 million of funding for the duration of the agreement. Payment of this funding is contingent on mutual agreement to study orders in order for any study to be included under the alliance. The Company made an upfront payment of $3.0 million to MD Anderson in the year ended December 31, 2020 and made an additional upfront payment of $3.0 million to MD Anderson in the year ended December 31, 2023. The Company is obligated to make further payments to MD Anderson each year upon the anniversary of the agreement effective date through the duration of the agreement term. These costs are expensed to research and development as MD Anderson renders the services under the strategic alliance. The agreement may be terminated by either party for material breach by the other party. Individual studies may be terminated for, among other things, material breach, health and safety concerns or where the institutional review board, the review board at the clinical site with oversight of the clinical study, requests termination of any study. Where any legal or regulatory authorization is finally withdrawn or terminated, the relevant study will also terminate automatically. For the years ended December 31, 2023, 2022, and 2021, the Company recorded $0.9 million, $1.4 million, and $1.0 million, respectively, in collaboration costs under this agreement as research and development expenses. Joint Venture and License Agreement with Allogene Overland Biopharm (CY) Limited (As Restated) On December 14, 2020, the Company entered into the License Agreement with Allogene Overland, a joint venture established by the Company and Overland, pursuant to the Share Purchase Agreement, for the purpose of developing, manufacturing and commercializing certain allogeneic CAR T cell therapies for patients in greater China, Taiwan, South Korea and Singapore (the JV Territory). Pursuant to the Share Purchase Agreement, the Company acquired Seed Preferred Shares in Allogene Overland representing 49% of Allogene Overland's outstanding stock as partial consideration for the License Agreement, and Overland acquired Seed Preferred Shares representing 51% of Allogene Overland's outstanding stock for $117.0 million in upfront and certain quarterly cash payments, to support operations of Allogene Overland. As of December 31, 2023, the Company and Overland are the sole equity holders in Allogene Overland. The Company received $40 million from Allogene Overland as partial consideration for the License Agreement. Pursuant to the License Agreement, the Company granted Allogene Overland an exclusive license to develop, manufacture and commercialize certain allogeneic CAR T cell candidates directed at four targets, BCMA, CD70, FLT3, and DLL3, in the JV Territory. As consideration, the Company would also be entitled to additional regulatory milestone payments of up to $40.0 million and, subject to certain conditions, tiered low-to-mid single-digit sales royalties. Subsequent to entering into the License Agreement, Allogene Overland assigned the License Agreement to a wholly-owned subsidiary, Allogene Overland Biopharm (HK) Limited (Allogene Overland HK). On April 1, 2022, Allogene Overland HK assigned the License Agreement to Allogene Overland Biopharm (PRC) Co., Limited. Promises that the Company concluded were distinct performance obligations in the License Agreement included: (1) the license of intellectual property and delivery of know-how, (2) the manufacturing license, related know-how and support, (3) know-how developed in future periods, and (4) participation in the joint steering committee. In order to determine the transaction price, the Company evaluated all the consideration to be received over the duration of the contract. Fixed consideration exists in the form of the upfront payment and Seed Preferred Shares in Allogene Overland. Regulatory milestones and royalties were considered variable consideration. The Company constrains the estimated variable consideration when it assesses it is probable that a significant reversal in the amount of cumulative revenue recognized may occur in future periods. Milestone fees were constrained and not included in the transaction price due to the uncertainties of research and development. The Company re-evaluates the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The Company estimated the fair value of the shares of Seed Preferred Stock at $79.0 million, using probability adjusted future cash infusions based on the upfront and certain quarterly cash payments of $117.0 million committed by Overland. The probability for the future quarterly cash payments of 65% was developed based on consideration of the Company's expectations for future cash infusions from Overland and was applied on a cumulative basis for each quarterly payment. The present value of the future quarterly cash payments was estimated using 11.9% annual discount rate. The fair value measurement is based on significant inputs not observable in the market and, therefore, represents a Level 3 measurement. The Company determined that the initial transaction price consists of the upfront payment of $40.0 million and noncash consideration of $79.0 million received in the form of the shares of Seed Preferred Stock. The allocation of the transaction price is performed based on standalone selling prices, which are based on estimated amounts that the Company would charge for a performance obligation if it were sold separately. The initial transaction price of $119.0 million was allocated as follows: (i) $114.0 million to the license of intellectual property and know-how, which was recognized upon grant of license and delivery of know-how in the consolidated financial statements for the year ended December 31, 2021 when the know-how was delivered; (ii) $2.3 million to the manufacturing license, related know-how and support, which will be recognized as services are delivered; (iii) $2.1 million to the know-how developed in future periods, which will be recognized as services are delivered, and (iv) $0.6 million to participation in the joint steering committee, which will be recognized over time as the services are delivered. Funds received in advance are recorded as deferred revenue and will be recognized as the performance obligations are satisfied. The Company has determined that Allogene Overland is a variable interest entity as of December 31, 2023 and 2022, respectively. The Company does not have the power to direct the activities which most significantly affect Allogene Overland's economic performance. Accordingly, for the years ended December 31, 2023 and 2022, the Company did not consolidate Allogene Overland because the Company determined that it was not the primary beneficiary. The Company's total equity investment in Allogene Overland as of December 31, 2023 and 2022 was zero and $4.5 million, respectively (see Note 8). For the years ended December 31, 2023, 2022 and 2021, the Company recognized $0.1 million, $0.2 million and $114.1 million, respectively, of collaboration revenue, primarily related to support services and the delivery of a performance obligation consisting of a license of intellectual property and related know-how which was delivered in the first quarter of 2021. For the year ended December 31, 2022, the Company recorded $0.7 million of net cost recoveries under the terms of the license agreement as a reduction to research and development expenses. For the years ended December 31, 2023 and 2021, the Company recorded zero net cost recoveries. Collaboration and License Agreement with Antion On January 5, 2022, the Company entered into an exclusive collaboration and global license agreement (Antion Collaboration and License Agreement) with Antion Biosciences SA (Antion) for Antion’s miRNA technology (miCAR), to advance multiplex gene silencing as an additional tool to develop next generation allogeneic CAR T products. Pursuant to the agreement, Antion will exclusively collaborate with the Company on oncology products for a defined period. The Company will also have exclusive worldwide rights to commercialize products incorporating Antion technology developed during the collaboration. The Antion Collaboration and License Agreement includes an exclusive research collaboration to conduct research and development of the use of Antion’s proprietary technologies to produce certain products for a defined period, which will be conducted in accordance with an agreed research plan and budget under the oversight of a joint steering committee. The Company will reimburse Antion's costs incurred in accordance with such plan and budget. In connection with the execution of the Antion Collaboration and License Agreement, the Company made an upfront payment to Antion of $3.5 million in return for a license to access Antion's technology in order to conduct research pursuant to the agreement. The upfront payment was fully recognized as research and development expense as the license had no foreseeable alternative future use. In addition, the Company made a $3.0 million investment in Antion's preferred stock. The Company accounts for its investment in Antion's preferred stock as an equity investment measured at cost less any impairment. In connection with this investment, a Company representative was appointed to Antion’s Board of Directors. In July 2023, the Company and Antion entered into an amendment to the Antion Collaboration and License Agreement. Under the terms of this amendment, Antion's exclusivity obligation relating to the collaboration was terminated; however, Antion agreed to certain restrictions on its ability to pursue products directed against specific targets. Also, in lieu of the Company's prior obligation to make a $3.0 million investment in Antion following the completion of certain milestones, the Company agreed to make a $2.0 million investment in Antion's preferred stock and acquired warrants to purchase an additional $3.0 million of Antion's preferred stock. The Company accounts for the fair value of the new investment of $1.0 million as an equity investment and the remaining $1.0 million was recorded as research and development expense. Under the Antion Collaboration and License Agreement, Antion will be eligible to receive up to $35.3 million for four products upon achievement of certain development and regulatory milestones. For each additional product, Antion will be eligible to receive $2.0 million upon achievement of a regulatory milestone. Antion is also entitled to receive a low single-digit royalty on the Company’s sales of licensed products, subject to certain reductions. For the years ended December 31, 2023 and 2022, the Company recorded $1.8 million and $5.0 million, respectively, in research and development expenses related to the upfront payment and collaboration costs. For the years ended December 31, 2023 and 2022, the Company recorded $0.4 million and zero, respectively, in research and development expenses related to the achievement of a milestone under the Antion Collaboration and License Agreement. For the year ended December 31, 2023 and 2022, the Company recorded $4.0 million and zero, respectively, in other expenses as impairment loss on its equity investment in Antion. As of December 31, 2023 and 2022, research and development expenses recorded in accrued and other liabilities relating to Antion were zero and $0.5 million, respectively. As of December 31, 2023 and 2022, the Company's total equity investment in Antion was zero and $3.0 million, respectively, and is recognized in other long-term assets in the consolidated balance sheets.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Income Tax Rate Reconciliation

Reconciliation of the benefit for income taxes calculated at the statutory rate to our benefit for income taxes is as follows:


	Year Ended December 31,
	2023		2022		2021
			(As Restated)		(As Restated)
	(in thousands)
Tax benefit at federal statutory rate	$	(68,725)	$	(71,487)	$	(38,231)
State taxes, net of federal benefit	(21,610)		(40,642)		8,731
Stock-based compensation	11,132		8,619		4,534
Research tax credits	(3,873)		(4,274)		(2,942)
Change in valuation allowance	82,526		106,111		27,889
Other	550		1,673		19
Benefit for incomes taxes	$	—	$	—	$	—

Schedule of Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets and liabilities are as follows:


	Year Ended December 31,
	2023		2022		2021
			(As Restated)		(As Restated)
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	211,124	$	174,222	$	144,133
Tax credit carryforwards	32,826		24,517		15,595
Intangibles	14,524		16,966		14,092
Accrued expenses	3,039		4,227		3,091
Lease liabilities	26,358		28,298		15,724
Stock based compensation	25,350		25,731		14,693
Investments	28,735		26,291		15,849
Capitalized R&D	73,492		41,273		—
Other	2,189		1,741		1,076
Total deferred tax assets	417,637		343,266		224,253
Deferred tax liabilities:
Fixed assets	—		—		(250)
Right of use leased assets	(17,652)		(23,392)		(12,478)
Other	(301)		(244)		(68)
Total deferred tax liabilities	(17,953)		(23,636)		(12,796)
Net deferred tax assets	399,684		319,630		211,457
Valuation allowance	(399,684)		(319,630)		(211,457)
Net deferred tax assets	$	—	$	—	$	—

Summary of Operating Loss Carryforwards

The following table sets forth the Company's federal and state NOL carryforwards and federal research and development tax credits as of December 31, 2023:


	Amount		Expiration
	(in thousands)
Net operating losses, federal	$	707,797	Indefinite
Net operating losses, federal	$	2	2037
Net operating losses, state	$	895,132	2037-2043
Tax credits, federal	$	26,383	2038-2043
Tax credits, state	$	20,856	Indefinite
California Competes Tax credits, state	$	9,000	2026 -2028

Schedule of Reconciliation of Unrecognized Tax Benefits

We apply the provisions of ASC Topic 740 to account for uncertain income tax positions. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
	2023		2022		2021
	(in thousands)
Balance at beginning of the year:	$	14,570	$	9,798	$	6,161
Additions based on tax positions related to current year	4,325		4,772		3,637
Additions to tax position of prior year	—		—		—
Reductions to tax position of prior years	—		—		—
Lapse of the applicable statute of limitations	—		—		—
Balance at end of the year	$	18,895	$	14,570	$	9,798

Stock-Based Compensation - Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)	$ 2.57
Expected dividend	0.00%
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum (in percent)	73.18%	70.82%
Expected volatility, maximum (in percent)	74.10%	73.39%
Expected risk-free interest rate, minimum (in percent)	3.45%	1.61%
Expected risk-free interest rate, maximum (in percent)	4.61%	4.12%
Expected dividend	0.00%	0.00%
2018 Equity Incentive Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)	$ 2.72	$ 7.08
Expected term in years	5 years 3 months 7 days	5 years 3 months
2018 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)	$ 7.23	$ 17.28
Expected term in years	6 years 29 days	6 years 29 days

Investment - Additional Information (Details) - USD ($)	12 Months Ended
Investment - Additional Information (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Investments, All Other Investments [Abstract]
Maximum remaining contractual maturities of available-for-sale securities	1 year	1 year
Realized losses on available-for-sale securities	$ 1,000,000	$ 0	$ 0
Net unrealized loss position	48,400,000	329,400,000
Accrued interest receivable from available-fore-sale investments	$ 1,700,000	$ 1,800,000
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets	Prepaid expenses and other current assets

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended		12 Months Ended
	Jul. 31, 2022	Feb. 28, 2019 ft² renewal	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) ft²	Oct. 31, 2018 USD ($) ft²	Aug. 31, 2018 ft²
Operating Leased Assets [Line Items]
Area of lease (in square feet) \| ft²						14,943	68,000
Operating lease term (in months)						124 months	127 months
Operating lease, extended term (in years)						7 years	7 years
Tenant improvements			$ 5.0
Additional area of lease (in square feet) \| ft²					47,566
Tenant improvement allowance						$ 0.8
Letter of credit			6.0	$ 6.0
Cash paid for amounts included in measurement of lease liabilities			$ 12.0
Weighted average discount rate, percent			6.22%
Weighted average remaining lease term (in years)			9 years 10 days
Rent expense for short-term leases			$ 0.0	0.0	$ 0.0
Asset retirement obligation			0.6	0.6
Non-cancellable purchase commitments			2.1
Onyx Development Group LLC
Operating Leased Assets [Line Items]
Letter of credit			4.3	$ 4.3
Agreement term	20 years
termination payment, amount			4.3
Newark
Operating Leased Assets [Line Items]
Operating lease term (in months)		188 months
Operating lease, extended term (in years)		10 years
Area of operating lease (in square feet) \| ft²		118,000
Number of options to extend lease \| renewal		2
Tenant improvement allowance utilized to date			$ 3.0
120 Months Lease Term
Operating Leased Assets [Line Items]
Operating lease term (in months)					120 months
Operating lease, extended term (in years)					8 years
124 Months Lease Term
Operating Leased Assets [Line Items]
Operating lease, extended term (in years)						8 years

Stockholders' Equity (Details) - $ / shares	12 Months Ended
Stockholders' Equity (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Equity [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0	0	0	0	0	0	0
Preferred stock, shares outstanding (in shares)	0	0	0	0	0	0	0	0
Common stock, shares authorized (in shares)	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	200,000,000
Common stock, shares issued (in shares)	168,642,238	144,438,304	168,175,221	167,133,664	145,740,333	144,031,588	143,723,171	143,569,902
Common stock, shares outstanding (in shares)	168,642,238	144,438,304	168,175,221	167,133,664	145,740,333	144,031,588	143,723,171	143,569,902
Dividends declared on common stock (in dollars per share)	$ 0	$ 0

Selected Quarterly Financial Data (Unaudited) - Income Statement (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended			73 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Condensed Consolidated Statements of Operations and Comprehensive Loss
Revenue recognized	$ 22	$ 22	$ 30	$ 27	$ 64	$ 39	$ 52	$ 103	$ 74	$ 130	$ 95	$ 156	$ 114,089
Operating expenses:
Research and development	45,977	62,038	80,238	63,641	57,171	60,156	142,276	117,327	188,253	180,968	242,914	256,387	220,176
General and administrative	17,041	18,524	18,884	18,897	19,509	19,897	37,408	39,406	54,449	58,303	71,673	79,305	74,105
Total operating expenses	63,018	80,562	99,122	82,538	76,680	80,053	179,684	156,733	242,702	239,271	327,832	335,692	294,281
Loss from operations	(62,996)	(80,540)	(99,092)	(82,511)	(76,616)	(80,014)	(179,632)	(156,630)	(242,628)	(239,141)	(327,737)	(335,536)	(180,192)
Other income (expense), net:
Interest and other income, net	6,205	3,778	2,059	1,002	315	492	5,837	807	12,042	1,809	18,307	4,566	1,714
Other expenses	(5,496)	(2,470)	(2,935)	(2,733)	(3,989)	915	(5,405)	(3,074)	(10,901)	(5,807)	(17,835)	(9,444)	(3,573)
Total other income (expense), net	709	1,308	(876)	(1,731)	(3,674)	1,407	432	(2,267)	1,141	(3,998)	472	(4,878)	(1,859)
Net loss	(62,287)	(79,232)	(99,968)	(84,242)	(80,290)	(78,607)	(179,200)	(158,897)	(241,487)	(243,139)	(327,265)	(340,414)	(182,051)	$ (1,562,200)
Other comprehensive income:
Net unrealized gain (loss) on available-for-sale investments	1,440	2,083	3,992	(1,486)	(2,223)	(6,682)	6,075	(8,905)	7,515	(10,391)	8,971	(7,359)	(2,835)
Net comprehensive loss	$ (60,847)	$ (77,149)	$ (95,976)	$ (85,728)	$ (82,513)	$ (85,289)	$ (173,125)	$ (167,802)	$ (233,972)	$ (253,530)	$ (318,294)	$ (347,773)	$ (184,886)
Net loss per share, basic (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)
Net loss per share, diluted (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)
Weighted-average number of shares used in computing net loss per share, basic (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386
Weighted-average number of shares used in computing net loss per share, diluted (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386
As Previously Reported
Condensed Consolidated Statements of Operations and Comprehensive Loss
Revenue recognized	$ 43	$ 44	$ 52	$ 49	$ 86	$ 61	$ 96	$ 147	$ 139	$ 196		$ 243	$ 38,489
Operating expenses:
Research and development	45,977	62,038	80,238	63,641	57,171	60,156	142,276	117,327	188,253	180,968		256,387	220,176
General and administrative	17,041	18,524	18,884	18,897	19,509	19,897	37,408	39,406	54,449	58,303		79,305	74,105
Total operating expenses	63,018	80,562	99,122	82,538	76,680	80,053	179,684	156,733	242,702	239,271		335,692	294,281
Loss from operations	(62,975)	(80,518)	(99,070)	(82,489)	(76,594)	(79,992)	(179,588)	(156,586)	(242,563)	(239,075)		(335,449)	(255,792)
Other income (expense), net:
Interest and other income, net	6,205	3,778	2,059	1,002	315	492	5,837	807	12,042	1,809		4,566	1,714
Other expenses	(4,545)	(1,249)	(1,693)	(1,661)	1,492	(350)	(2,942)	1,142	(7,487)	(519)		(1,749)	(2,927)
Total other income (expense), net	1,660	2,529	366	(659)	1,807	142	2,895	1,949	4,555	1,290		2,817	(1,213)
Net loss	(61,315)	(77,989)	(98,704)	(83,148)	(74,787)	(79,850)	(176,693)	(154,637)	(238,008)	(237,785)		(332,632)	(257,005)
Other comprehensive income:
Net unrealized gain (loss) on available-for-sale investments	1,440	2,083	3,992	(1,486)	(2,223)	(6,682)	6,075	(8,905)	7,515	(10,391)
Net comprehensive loss	$ (59,875)	$ (75,906)	$ (94,712)	$ (84,634)	$ (77,010)	$ (86,532)	$ (170,618)	$ (163,542)	$ (230,493)	$ (248,176)		$ (339,991)	$ (259,840)
Net loss per share, basic (in dollars per share)	$ (0.37)	$ (0.53)	$ (0.68)	$ (0.58)	$ (0.52)	$ (0.56)	$ (1.21)	$ (1.09)	$ (1.55)	$ (1.67)		$ (2.32)	$ (1.89)
Net loss per share, diluted (in dollars per share)	$ (0.37)	$ (0.53)	$ (0.68)	$ (0.58)	$ (0.52)	$ (0.56)	$ (1.21)	$ (1.09)	$ (1.55)	$ (1.67)		$ (2.32)	$ (1.89)
Weighted-average number of shares used in computing net loss per share, basic (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469		143,147,165	135,820,386
Weighted-average number of shares used in computing net loss per share, diluted (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469		143,147,165	135,820,386
Restatement Adjustment
Condensed Consolidated Statements of Operations and Comprehensive Loss
Revenue recognized	$ (21)	$ (22)	$ (22)	$ (22)	$ (22)	$ (22)	$ (44)	$ (44)	$ (65)	$ (66)		$ (87)	$ 75,600
Operating expenses:
Research and development	0	0	0	0	0	0	0	0	0	0		0	0
General and administrative	0	0	0	0	0	0	0	0	0	0		0	0
Total operating expenses	0	0	0	0	0	0	0	0	0	0		0	0
Loss from operations	(21)	(22)	(22)	(22)	(22)	(22)	(44)	(44)	(65)	(66)		(87)	75,600
Other income (expense), net:
Interest and other income, net	0	0	0	0	0	0	0	0	0	0		0	0
Other expenses	(951)	(1,221)	(1,242)	(1,072)	(5,481)	1,265	(2,463)	(4,216)	(3,414)	(5,288)		(7,695)	(646)
Total other income (expense), net	(951)	(1,221)	(1,242)	(1,072)	(5,481)	1,265	(2,463)	(4,216)	(3,414)	(5,288)		(7,695)	(646)
Net loss	(972)	(1,243)	(1,264)	(1,094)	(5,503)	1,243	(2,507)	(4,260)	(3,479)	(5,354)		(7,782)	74,954
Other comprehensive income:
Net unrealized gain (loss) on available-for-sale investments	0	0	0	0	0	0	0	0	0	0
Net comprehensive loss	$ (972)	$ (1,243)	$ (1,264)	$ (1,094)	$ (5,503)	$ 1,243	$ (2,507)	$ (4,260)	$ (3,479)	$ (5,354)		$ (7,782)	$ 74,954

Description of Business and Summary of Significant Accounting Policies - Reconciliation of Restated Financial Statements - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Consolidated Balance Sheets
Equity method investments	$ 3,645	$ 6,450	$ 11,946	$ 14,381	$ 17,317	$ 20,951	$ 23,673	$ 27,663
Total assets	642,837	713,411	773,007	750,128	821,579	894,477	955,621	978,091
Deferred revenue	86	86	86	86	95	99	104	147
Total current liabilities	37,079	37,486	54,578	59,398	53,728	48,082	44,177	36,618
Other long-term liabilities	5,179	5,188	5,197	5,205	5,847	6,288	6,729	7,171
Total liabilities	130,604	132,776	151,596	158,118	154,697	151,076	149,138	112,823
Accumulated deficit	(1,562,233)	(1,476,455)	(1,414,168)	(1,334,936)	(1,234,968)	(1,137,693)	(1,053,451)	(973,161)	$ (894,554)
Total stockholders’ equity (deficit)	512,233	580,635	621,411	592,010	666,882	743,401	806,483	865,267	925,200	$ 1,013,457
Total liabilities and stockholders’ equity	$ 642,837	713,411	773,007	750,128	821,579	894,477	955,621	978,091
As Previously Reported
Condensed Consolidated Balance Sheets
Equity method investments		5,365	9,910	11,124	12,817	14,046	15,696	14,204
Total assets		712,326	770,971	746,871	817,079	887,572	947,644	964,632
Deferred revenue		236	229	273	885	889	836	406
Total current liabilities		37,636	54,721	59,585	54,518	48,872	44,909	36,877
Other long-term liabilities		1,486	1,523	1,510	1,569	2,033	2,554	3,490
Total liabilities		129,224	148,065	154,609	151,209	147,611	145,695	109,402
Accumulated deficit		(1,473,988)	(1,412,673)	(1,334,684)	(1,235,980)	(1,141,133)	(1,057,985)	(983,198)	(903,348)
Total stockholders’ equity (deficit)		583,102	622,906	592,262	665,870	739,961	801,949	855,230	916,406
Total liabilities and stockholders’ equity		712,326	770,971	746,871	817,079	887,572	947,644	964,632
Restatement Adjustment
Condensed Consolidated Balance Sheets
Equity method investments		1,085	2,036	3,257	4,500	6,905	7,977	13,459
Total assets		1,085	2,036	3,257	4,500	6,905	7,977	13,459
Deferred revenue		(150)	(143)	(187)	(790)	(790)	(732)	(259)
Total current liabilities		(150)	(143)	(187)	(790)	(790)	(732)	(259)
Other long-term liabilities		3,702	3,674	3,695	4,278	4,255	4,175	3,681
Total liabilities		3,552	3,531	3,509	3,488	3,465	3,443	3,421
Accumulated deficit		(2,467)	(1,495)	(252)	1,012	3,440	4,534	10,037	8,794
Total stockholders’ equity (deficit)		(2,467)	(1,495)	(252)	1,012	3,440	4,534	10,037	$ 8,794
Total liabilities and stockholders’ equity		$ 1,085	$ 2,036	$ 3,257	$ 4,500	$ 6,905	$ 7,977	$ 13,459

Stock-Based Compensation - Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum (in percent)	67.32%	74.20%
Expected volatility, maximum (in percent)	85.05%	85.63%
Expected risk-free interest rate, minimum (in percent)	4.05%	0.86%
Expected risk-free interest rate, maximum (in percent)	5.35%	3.88%
Dividend yield	0.00%	0.00%
Employee Stock Purchase Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	6 months	6 months
Employee Stock Purchase Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	2 years	2 years

Stock-Based Compensation - Stock Option Activity (Details) - 2018 Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Number of Options
Beginning balance (in shares)	17,569,575
Options granted (in shares)	10,315,270
Options exercised (in shares)	(850,396)
Options forfeited (in shares)	(5,221,503)
Ending balance (in shares)	21,812,946	17,569,575
Number of options, exercisable (in shares)	18,687,724
Number of options, vested and expected to vest (in shares)	21,812,946
Weighted- Average Exercise Price
Beginning balance (in dollars per share)	$ 12.90
Options granted (in dollars per share)	4.94
Options exercised (in dollars per share)	2.45
Options forfeited (in dollars per share)	11.31
Ending balance (in dollars per share)	9.93	$ 12.90
Weighted-average exercise price, exercisable (in dollars per share)	9.98
Weighted-average exercise price, vested and expected to vest (in dollars per share)	$ 9.93
Weighted-average remaining contract term, options vested and expected to vest	7 years 6 months 10 days	7 years 8 months 23 days
Weighted-average remaining contract term, exercisable	7 years 6 months 21 days
Weighted-average remaining contract term	7 years 6 months 10 days
Aggregate intrinsic value, beginning balance	$ 6,658
Aggregate intrinsic value, exercised	2,334	$ 1,900	$ 21,900
Aggregate intrinsic value, ending balance	662	$ 6,658
Aggregate intrinsic value, exercisable	639
Aggregate intrinsic value, vested and expected to vest	$ 662

Commitments and Contingencies - Summary of Undiscounted Future Non-Cancellable Lease Payments Under Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
2024	$ 12,447
2025	12,627
2026	12,819
2027	13,257
2027 and thereafter	77,234
Total undiscounted lease payments	128,384
Less: Present value adjustment	(33,263)
Total	$ 95,121	$ 101,124

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Leases

In August 2018, the Company entered into an operating lease agreement (HQ Lease) for new office and laboratory space which consists of approximately 68,000 square feet located in South San Francisco, California. The lease term was 127 months beginning August 2018 through February 2029 with an option to extend the term for 7 years which was not reasonably assured of exercise. The Company has made certain tenant improvements, including the addition of laboratory space, and has received $5.0 million of tenant improvement allowances up to December 31, 2023. The rent payments began on March 1, 2019 after an abatement period. In December 2021, the Company amended its lease agreement to lease an additional 47,566 square feet of office and laboratory space in South San Francisco, California, as part of the same building as the Company’s current headquarters. The lease term commenced in April 2022 and is for a period of 120 months. The rent payments for the expansion premises began in August 2022 after an abatement period. The lease term for the existing premises was also extended and the lease for both the existing and expansion premises will expire on March 31, 2032 with an option to extend the term for 8 years which is not reasonably assured of exercise.

In October 2018, the Company entered into an operating lease agreement for office and laboratory space which consists of 14,943 square feet located in South San Francisco, California. The lease term was 124 months beginning November 2018 through February 2029, with an option to extend the term for another 7 years which was not reasonably assured of exercise. The Company has made certain tenant improvements, including the upgrading of current office and laboratory space with a lease incentive allowance of $0.8 million. Rent payments began in November 2018. In December 2021, the Company amended its lease agreement to extend the term of the lease to be co-terminus with the HQ Lease. The lease term will expire March 31, 2032 with an option to extend the term for 8 years which is not reasonably assured of exercise.

In February 2019, the Company entered into a lease agreement for approximately 118,000 square feet of space to develop a cell therapy manufacturing facility in Newark, California. The lease term is 188 months and began in November 2020. Upon certain conditions, the Company has two ten-year options to extend the lease, both of which are not reasonably

assured of exercise. The Company has received $3.0 million of tenant improvement allowances for costs related to the design and construction of certain Company improvements.

The Company maintains letters of credit for the benefit of landlords which is disclosed as restricted cash in the consolidated balance sheet. Restricted cash related to letters of credit due to landlords was $6.0 million as of December 31, 2023 and 2022.

The balance sheet classification of our lease liabilities were as follows (in thousands):


	December 31, 2023		December 31, 2022
Operating lease liabilities
Current portion included in accrued and other current liabilities	$	6,775	$	6,002
Long-term portion of lease liabilities	88,346		95,122
Total operating lease liabilities	$	95,121	$	101,124

The components of lease costs for operating leases, which were recognized in operating expenses, were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Operating lease cost	$	12,711	$	11,664	$	7,513
Variable lease cost	3,102		2,139		1,629
Total lease costs	$	15,813	$	13,803	$	9,142

Cash paid for amounts included in the measurement of lease liabilities for the year ended December 31, 2023 was $12.0 million and was included in net cash used in operating activities in the Company's consolidated statements of cash flows.

The undiscounted future non-cancellable lease payments under the Company's operating leases as of December 31, 2023 is as follows:


Year ending December 31:	(in thousands)
2024	$	12,447
2025	12,627
2026	12,819
2027	13,257
2028 and thereafter	77,234
Total undiscounted lease payments	128,384
Less: Present value adjustment	(33,263)
Total	$	95,121

Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. In determining the present value of lease payments, the Company uses its estimated incremental borrowing rate. The weighted average discount rate used to determine the operating lease liability was 6.22%. As of December 31, 2023, the weighted average remaining lease term for our operating leases is 9.03 years.

The Company did not incur any significant rent expense for short-term leases for the years ended December 31, 2023, 2022 and 2021, respectively.

Certain lease agreements require the Company to return designated areas of leased space to its original condition upon termination of the lease agreement. At the inception of such leases, the Company records an asset retirement obligation and a corresponding capital asset in an amount equal to the estimated fair value of the obligation. To determine the fair value of the obligation, the Company estimates the cost for a third-party to perform the restoration work. In subsequent periods, for each asset retirement obligation, the Company records interest expense to accrete the asset retirement obligation liability to full value and depreciate each capitalized asset retirement obligation asset, both over the term of the associated lease agreement. Asset retirement obligations were $0.6 million as of December 31, 2023 and 2022.

Other Commitments

Solar Power Purchase and Energy Services Agreement

In July 2020, the Company entered into a Solar Power Purchase and Energy Services Agreement for the installation and operation of a solar photovoltaic generating system and battery energy storage system at the Company's cell therapy manufacturing facility in Newark, California. The agreement has a term of 20 years and commenced in September 2022. The Company is obligated to pay for electricity generated from the system at an agreed rate for the duration of the agreement term. Termination of the agreement by the Company will result in a termination payment due of approximately $4.3 million. In connection with the agreement, the Company maintains a letter of credit for the benefit of the service provider in the amount of $4.3 million which is recorded as restricted cash in the consolidated balance sheets as of December 31, 2023 and 2022.

License Agreements for Intellectual Property

The Company has entered into certain license agreements for intellectual property which is used as part of its development and manufacturing processes. Each of these respective agreements are generally cancellable by the Company. These agreements require payment of annual license fees and may include conditional milestone payments for achievement of specific research, clinical and commercial events, and royalty payments. The timing and likelihood of any significant conditional milestone payments or royalty payments becoming due was not probable as of December 31, 2023.

Purchase Commitments

In the normal course of business, the Company enters into various purchase commitments with third-party contract manufacturers for the manufacture and processing of our product candidates and related raw materials, and the Company has entered into other contracts in the normal course of business with contract research organizations for clinical trials and other vendors for other services and products for operating purposes. These agreements generally provide for termination or cancellation, other than for costs already incurred. As of December 31, 2023, the Company had non-cancellable purchase commitments of $2.1 million.

Contingencies

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown, because it involves claims that may be made against the Company in the future, but have not yet been made. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated.

Indemnification

In accordance with the Company’s amended and restated certificate of incorporation and amended and restated bylaws, the Company has indemnification obligations to its officers and directors for certain events or occurrences, subject to certain limits, while they are serving in such capacity. There have been no claims to date, and the Company has a directors and officers liability insurance policy that may enable it to recover a portion of any amounts paid for future claims.

Investments - Schedule of Fair Values of Available For Sale Debt Investments by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Investments, All Other Investments [Abstract]
Due in 1 year or less	$ 365,542	$ 456,497
Due in 1 - 2 years	0	59,151
Due in 3 years	0	0
Instruments not due at a single maturity date	78,536	10,679
Total cash equivalents and investments	$ 444,078	$ 526,327

Net Loss and Net Loss Per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss and Net Loss Per Share

The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except share and per share data):


	Year Ended December 31,
	2023		2022		2021
			(As Restated)		(As Restated)
Numerator:
Net loss	$	(327,265)	$	(340,414)	$	(182,051)
Denominator:
Weighted average common shares outstanding	156,931,778		143,147,165		135,820,386
Net loss per share, basic and diluted	$	(2.09)	$	(2.38)	$	(1.34)

Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share as the inclusion of all potential dilutive securities would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:


	Year Ended December 31,
	2023	2022	2021
Stock options to purchase common stock	21,812,946	17,569,575	10,239,167
Restricted stock units subject to vesting	12,180,471	5,493,406	4,261,108
Expected shares purchased under Employee Stock Purchase Plan	2,168,264	1,092,314	474,966
Founder shares subject to future vesting	—	—	1,514,424
Early exercised stock options subject to future vesting	29,180	138,841	720,321
Total	36,190,861	24,294,136	17,209,986

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (327,265)	$ (340,414)	$ (182,051)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	65,951	83,600	80,818
Depreciation and amortization	14,199	14,295	10,454
Net amortization/accretion on investment securities	(6,809)	2,891	6,955
Impairment of long-lived asset	13,245	0	0
Impairment of equity investment and equity method investment	7,000	0	0
Non-cash rent expense	642	2,433	2,611
Non-cash collaboration revenue - related party	(63)	(104)	(75,740)
Share of loss from equity method investments	10,672	12,883	4,090
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,086	2,517	3,199
Other long-term assets	(1,455)	(3,334)	(646)
Accounts payable	(7,502)	4,868	(767)
Accrued and other current liabilities	(6,820)	1,749	3,652
Deferred revenue	(3)	(21)	(38,297)
Other long-term liabilities	(611)	(1,882)	910
Net cash used in operating activities	(237,733)	(220,519)	(184,812)
Cash flows from investing activities:
Purchases of property and equipment	(1,516)	(5,191)	(21,446)
Purchase of stock in equity method investment	0	0	(17,710)
Proceeds from sales of investments	5,623	0	0
Proceeds from maturities of investments	597,811	359,459	728,394
Purchase of investments	(438,629)	(248,109)	(525,583)
Net cash provided by (used in) investing activities	163,289	106,159	163,655
Cash flows from financing activities:
Proceeds from issuance of common stock from ATM offering, net of commissions and issuance costs	91,112	0	0
Proceeds from issuance of common stock and upon exercise of stock options	2,087	489	8,346
Proceeds from issuance of common stock under the employee stock purchase plan	2,496	2,461	3,617
Net cash provided by financing activities	95,695	2,950	11,963
Net increase (decrease) in cash, cash equivalents and restricted cash	21,251	(111,410)	(9,194)
Cash, cash equivalents and restricted cash — beginning of period	72,196	183,606	192,800
Cash, cash equivalents and restricted cash — end of period	93,447	72,196	183,606
Non-cash operating, investing and financing activities:
Right-of-use asset obtained in exchange for lease liability	0	31,361	20,079
Property and equipment purchases in accounts payable and accrued and other current liabilities	0	678	1,725
Capitalized cloud computing costs included in accounts payable and accrued and other current liabilities	0	415	0
Non-cash deferred revenue and other long-term liabilities	3,094	3,157	3,260
Supplemental disclosure:
Cash paid for amounts included in the measurement of lease liabilities	(12,049)	(9,540)	(6,013)
Cash received for amounts related to tenant improvement allowances from lessors	$ 0	$ 325	$ 1,111

Commitments and Contingencies - Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Current portion included in accrued and other current liabilities	$ 6,775				$ 6,002
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued and other current liabilities				Accrued and other current liabilities
Long-term portion of lease liabilities	$ 88,346	$ 90,102	$ 91,821	$ 93,514	$ 95,122	$ 96,706	$ 98,232	$ 69,035
Total operating lease liabilities	$ 95,121				$ 101,124

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2023

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

The following tables present selected quarterly financial data for 2023 and 2022 (in thousands, except share and per share data):


	March 31, 2023						March 31, 2022
Condensed Consolidated Balance Sheets	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Assets
Current assets:
Cash and cash equivalents	$	109,931	$	—	$	109,931	$	84,514	$	—	$	84,514
Short-term investments	361,293		—		361,293		364,536		—		364,536
Prepaid expenses and other current assets	10,241		—		10,241		20,694		—		20,694
Total current assets	481,465		—		481,465		469,744		—		469,744
Long-term investments	42,788		—		42,788		284,093		—		284,093
Operating lease right-of-use asset	81,964		—		81,964		57,057		—		57,057
Property and equipment, net	109,849		—		109,849		120,200		—		120,200
Restricted cash	10,292		—		10,292		10,292		—		10,292
Other long-term assets	9,389		—		9,389		9,042		—		9,042
Equity method investments	11,124		3,257		14,381		14,204		13,459		27,663
Total assets	746,871		3,257		750,128		964,632		13,459		978,091
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	14,688		—		14,688		8,708		—		8,708
Accrued and other current liabilities	44,624		—		44,624		27,763		—		27,763
Deferred revenue	273		(187)		86		406		(259)		147
Total current liabilities	59,585		(187)		59,398		36,877		(259)		36,618
Lease liability, noncurrent	93,514		—		93,514		69,035		—		69,035
Other long-term liabilities	1,510		3,695		5,205		3,490		3,681		7,171
Total liabilities	154,609		3,509		158,118		109,402		3,421		112,823
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 authorized as of March 31, 2023 and March 31, 2022; no shares were issued and outstanding as of March 31, 2023 and March 31, 2022	—		—		—		—		—		—
Common stock, $0.001 par value: 400,000,000 and 200,000,000 shares authorized as of March 31, 2023 and March 31, 2022, respectively; 145,740,333 and 143,569,902 shares issued and outstanding as of March 31, 2023 and March 31, 2022, respectively	146		—		146		143		—		143
Additional paid-in capital	1,932,734		—		1,932,734		1,847,534		—		1,847,534
Accumulated deficit	(1,334,684)		(252)		(1,334,936)		(983,198)		10,037		(973,161)
Accumulated other comprehensive loss	(5,934)		—		(5,934)		(9,249)		—		(9,249)
Total stockholders’ equity (deficit)	592,262		(252)		592,010		855,230		10,037		865,267
Total liabilities and stockholders’ equity	746,871		3,257		750,128		964,632		13,459		978,091


	Three Months ended March 31, 2023						Three Months ended March 31, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	52	$	(22)	$	30	$	61	$	(22)	$	39
Operating expenses:
Research and development	80,238		—		80,238		60,156		—		60,156
General and administrative	18,884		—		18,884		19,897		—		19,897
Total operating expenses	99,122		—		99,122		80,053		—		80,053
Loss from operations	(99,070)		(22)		(99,092)		(79,992)		(22)		(80,014)
Other income (expense), net:
Interest and other income, net	2,059		—		2,059		492		—		492
Other expenses	(1,693)		(1,242)		(2,935)		(350)		1,265		915
Total other income (expense), net	366		(1,242)		(876)		142		1,265		1,407
Net loss	(98,704)		(1,264)		(99,968)		(79,850)		1,243		(78,607)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	3,992		—		3,992		(6,682)		—		(6,682)
Net comprehensive loss	(94,712)		(1,264)		(95,976)		(86,532)		1,243		(85,289)
Net loss per share, basic and diluted	(0.68)				(0.69)		(0.56)				(0.56)
Weighted-average number of shares used in computing net loss per share, basic and diluted	144,563,829				144,563,829		141,356,306				141,356,306


	Three Months ended March 31, 2023						Three Months ended March 31, 2022
Condensed Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(98,704)	$	(1,264)	$	(99,968)	$	(79,850)	$	1,243	$	(78,607)
Non-cash collaboration revenue - related party	—		(20)		(20)		—		(26)		(26)
Share of losses from equity method investments	1,693		1,242		2,935		3,800		(1,265)		2,535
Changes in operating assets and liabilities:
Deferred revenue	(612)		609		(3)		(17)		14		(3)
Other long-term liabilities	(59)		(567)		(626)		(635)		34		(601)
Net cash used in operating activities	(66,639)		—		(66,639)		(68,237)		—		(68,237)


	June 30, 2023						June 30, 2022
Condensed Consolidated Balance Sheets	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Assets
Current assets:
Cash and cash equivalents	$	154,758	$	—	$	154,758	$	96,041	$	—	$	96,041
Short-term investments	337,204		—		337,204		394,451		—		394,451
Prepaid expenses and other current assets	10,139		—		10,139		22,536		—		22,536
Total current assets	502,101		—		502,101		513,028		—		513,028
Long-term investments	52,586		—		52,586		195,637		—		195,637
Operating lease right-of-use asset	80,314		—		80,314		86,837		—		86,837
Property and equipment, net	106,386		—		106,386		117,216		—		117,216
Restricted cash	10,292		—		10,292		10,292		—		10,292
Other long-term assets	9,382		—		9,382		8,938		—		8,938
Equity method investments	9,910		2,036		11,946		15,696		7,977		23,673
Total assets	770,971		2,036		773,007		947,644		7,977		955,621
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	10,229		—		10,229		9,713		—		9,713
Accrued and other current liabilities	44,263		—		44,263		34,360		—		34,360
Deferred revenue	229		(143)		86		836		(732)		104
Total current liabilities	54,721		(143)		54,578		44,909		(732)		44,177
Lease liability, noncurrent	91,821		—		91,821		98,232		—		98,232
Other long-term liabilities	1,523		3,674		5,197		2,554		4,175		6,729
Total liabilities	148,065		3,531		151,596		145,695		3,443		149,138
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 authorized as of June 30, 2023 and June 30, 2022; no shares were issued and outstanding as of June 30, 2023 and June 30, 2022	—		—		—		—		—		—
Common stock, $0.001 par value: 400,000,000 shares authorized as of June 30, 2023 and June 30, 2022; 167,133,664 and 143,723,171 shares issued and outstanding as of June 30, 2023 and June 30, 2022, respectively	167		—		167		144		—		144
Additional paid-in capital	2,039,263		—		2,039,263		1,871,262		—		1,871,262
Accumulated deficit	(1,412,673)		(1,495)		(1,414,168)		(1,057,985)		4,534		(1,053,451)
Accumulated other comprehensive loss	(3,851)		—		(3,851)		(11,472)		—		(11,472)
Total stockholders’ equity (deficit)	622,906		(1,495)		621,411		801,949		4,534		806,483
Total liabilities and stockholders’ equity	770,971		2,036		773,007		947,644		7,977		955,621


	Three Months ended June 30, 2023						Three Months ended June 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	44	$	(22)	$	22	$	86	$	(22)	$	64
Operating expenses:
Research and development	62,038		—		62,038		57,171		—		57,171
General and administrative	18,524		—		18,524		19,509		—		19,509
Total operating expenses	80,562		—		80,562		76,680		—		76,680
Loss from operations	(80,518)		(22)		(80,540)		(76,594)		(22)		(76,616)
Other income (expense), net:
Interest and other income, net	3,778		—		3,778		315		—		315
Other expenses	(1,249)		(1,221)		(2,470)		1,492		(5,481)		(3,989)
Total other income (expense), net	2,529		(1,221)		1,308		1,807		(5,481)		(3,674)
Net loss	(77,989)		(1,243)		(79,232)		(74,787)		(5,503)		(80,290)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	2,083		—		2,083		(2,223)		—		(2,223)
Net comprehensive loss	(75,906)		(1,243)		(77,149)		(77,010)		(5,503)		(82,513)
Net loss per share, basic and diluted	(0.53)				(0.54)		(0.52)				(0.56)
Weighted-average number of shares used in computing net loss per share, basic and diluted	146,795,826				146,795,826		143,385,045				143,385,045


	Six Months ended June 30, 2023						Six Months ended June 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	96	$	(44)	$	52	$	147	$	(44)	$	103
Operating expenses:
Research and development	142,276		—		142,276		117,327		—		117,327
General and administrative	37,408		—		37,408		39,406		—		39,406
Total operating expenses	179,684		—		179,684		156,733		—		156,733
Loss from operations	(179,588)		(44)		(179,632)		(156,586)		(44)		(156,630)
Other income (expense), net:
Interest and other income, net	5,837		—		5,837		807		—		807
Other expenses	(2,942)		(2,463)		(5,405)		1,142		(4,216)		(3,074)
Total other income (expense), net	2,895		(2,463)		432		1,949		(4,216)		(2,267)
Net loss	(176,693)		(2,507)		(179,200)		(154,637)		(4,260)		(158,897)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	6,075		—		6,075		(8,905)		—		(8,905)
Net comprehensive loss	(170,618)		(2,507)		(173,125)		(163,542)		(4,260)		(167,802)
Net loss per share, basic and diluted	(1.21)				(1.23)		(1.09)				(1.12)
Weighted-average number of shares used in computing net loss per share, basic and diluted	145,685,993				145,685,993		142,376,280				142,376,280


	Six Months ended June 30, 2023						Six Months ended June 30, 2022
Condensed Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(176,693)	$	(2,507)	$	(179,200)	$	(154,637)	$	(4,260)	$	(158,897)
Non-cash collaboration revenue - related party	—		(34)		(34)		—		(69)		(69)
Share of losses from equity method investments	2,907		2,463		5,370		2,309		4,216		6,525
Changes in operating assets and liabilities:
Deferred revenue	(656)		653		(3)		413		(430)		(17)
Other long-term liabilities	(46)		(575)		(621)		(1,571)		543		(1,028)
Net cash used in operating activities	(128,496)		—		(128,496)		(110,768)		—		(110,768)


	September 30, 2023						September 30, 2022
Condensed Consolidated Balance Sheets	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Assets
Current assets:
Cash and cash equivalents	$	69,246	$	—	$	69,246	$	74,357	$	—	$	74,357
Short-term investments	396,259		—		396,259		477,872		—		477,872
Prepaid expenses and other current assets	7,949		—		7,949		16,832		—		16,832
Total current assets	473,454		—		473,454		569,061		—		569,061
Long-term investments	32,170		—		32,170		85,108		—		85,108
Operating lease right-of-use asset	78,643		—		78,643		85,245		—		85,245
Property and equipment, net	102,826		—		102,826		114,442		—		114,442
Restricted cash	10,292		—		10,292		10,292		—		10,292
Other long-term assets	9,576		—		9,576		9,378		—		9,378
Equity method investments	5,365		1,085		6,450		14,046		6,905		20,951
Total assets	712,326		1,085		713,411		887,572		6,905		894,477
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	6,205		—		6,205		11,045		—		11,045
Accrued and other current liabilities	31,195		—		31,195		36,938		—		36,938
Deferred revenue	236		(150)		86		889		(790)		99
Total current liabilities	37,636		(150)		37,486		48,872		(790)		48,082
Lease liability, noncurrent	90,102		—		90,102		96,706		—		96,706
Other long-term liabilities	1,486		3,702		5,188		2,033		4,255		6,288
Total liabilities	129,224		3,552		132,776		147,611		3,465		151,076
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 authorized as of September 30, 2023 and September 30, 2022; no shares were issued and outstanding as of September 30, 2023 and September 30, 2022	—		—		—		—		—		—
Common stock, $0.001 par value: 400,000,000 shares authorized as of September 30, 2023 and September 30, 2022; 168,175,221 and 144,031,588 shares issued and outstanding as of September 30, 2023 and September 30, 2022, respectively	168		—		168		144		—		144
Additional paid-in capital	2,059,333		—		2,059,333		1,893,908		—		1,893,908
Accumulated deficit	(1,473,988)		(2,467)		(1,476,455)		(1,141,133)		3,440		(1,137,693)
Accumulated other comprehensive loss	(2,411)		—		(2,411)		(12,958)		—		(12,958)
Total stockholders’ equity (deficit)	583,102		(2,467)		580,635		739,961		3,440		743,401
Total liabilities and stockholders’ equity	712,326		1,085		713,411		887,572		6,905		894,477


	Three Months ended September 30, 2023						Three Months ended September 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	43	$	(21)	$	22	$	49	$	(22)	$	27
Operating expenses:
Research and development	45,977		—		45,977		63,641		—		63,641
General and administrative	17,041		—		17,041		18,897		—		18,897
Total operating expenses	63,018		—		63,018		82,538		—		82,538
Loss from operations	(62,975)		(21)		(62,996)		(82,489)		(22)		(82,511)
Other income (expense), net:
Interest and other income, net	6,205		—		6,205		1,002		—		1,002
Other expenses	(4,545)		(951)		(5,496)		(1,661)		(1,072)		(2,733)
Total other income (expense), net	1,660		(951)		709		(659)		(1,072)		(1,731)
Net loss	(61,315)		(972)		(62,287)		(83,148)		(1,094)		(84,242)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	1,440		—		1,440		(1,486)		—		(1,486)
Net comprehensive loss	(59,875)		(972)		(60,847)		(84,634)		(1,094)		(85,728)
Net loss per share, basic and diluted	(0.37)				(0.37)		(0.58)				(0.59)
Weighted-average number of shares used in computing net loss per share, basic and diluted	167,649,010				167,649,010		143,661,721				143,661,721


	Nine Months ended September 30, 2023						Nine Months ended September 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	139	$	(65)	$	74	$	196	$	(66)	$	130
Operating expenses:
Research and development	188,253		—		188,253		180,968		—		180,968
General and administrative	54,449		—		54,449		58,303		—		58,303
Total operating expenses	242,702		—		242,702		239,271		—		239,271
Loss from operations	(242,563)		(65)		(242,628)		(239,075)		(66)		(239,141)
Other income (expense), net:
Interest and other income, net	12,042		—		12,042		1,809		—		1,809
Other expenses	(7,487)		(3,414)		(10,901)		(519)		(5,288)		(5,807)
Total other income (expense), net	4,555		(3,414)		1,141		1,290		(5,288)		(3,998)
Net loss	(238,008)		(3,479)		(241,487)		(237,785)		(5,354)		(243,139)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	7,515		—		7,515		(10,391)		—		(10,391)
Net comprehensive loss	(230,493)		(3,479)		(233,972)		(248,176)		(5,354)		(253,530)
Net loss per share, basic and diluted	(1.55)				(1.58)		(1.67)				(1.70)
Weighted-average number of shares used in computing net loss per share, basic and diluted	153,087,449				153,087,449		142,809,469				142,809,469


	Nine Months ended September 30, 2023						Nine Months ended September 30, 2022
Condensed Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(238,008)	$	(3,479)	$	(241,487)	$	(237,785)	$	(5,354)	$	(243,139)
Non-cash collaboration revenue - related party	—		(49)		(49)		—		(87)		(87)
Share of losses from equity method investments	7,452		3,414		10,866		3,959		5,288		9,247
Changes in operating assets and liabilities:
Deferred revenue	(649)		646		(3)		466		(485)		(19)
Other long-term liabilities	(83)		(532)		(615)		(2,092)		638		(1,454)
Net cash used in operating activities	(184,026)		—		(184,026)		(158,423)		—		(158,423)

Selected Quarterly Financial Data (Unaudited) - Cash Flow Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Consolidated Statements of Cash Flow
Net loss	$ (99,968)	$ (78,607)	$ (179,200)	$ (158,897)	$ (241,487)	$ (243,139)	$ (327,265)	$ (340,414)	$ (182,051)
Non-cash collaboration revenue - related party	(20)	(26)	(34)	(69)	(49)	(87)	(63)	(104)	(75,740)
Share of loss from equity method investments	2,935	2,535	5,370	6,525	10,866	9,247	10,672	12,883	4,090
Changes in operating assets and liabilities:
Deferred revenue	(3)	(3)	(3)	(17)	(3)	(19)	(3)	(21)	(38,297)
Other long-term liabilities	(626)	(601)	(621)	(1,028)	(615)	(1,454)	(611)	(1,882)	910
Net cash used in operating activities	(66,639)	(68,237)	(128,496)	(110,768)	(184,026)	(158,423)	$ (237,733)	(220,519)	(184,812)
As Previously Reported
Condensed Consolidated Statements of Cash Flow
Net loss	(98,704)	(79,850)	(176,693)	(154,637)	(238,008)	(237,785)		(332,632)	(257,005)
Non-cash collaboration revenue - related party	0	0	0	0	0	0		0	0
Share of loss from equity method investments	1,693	3,800	2,907	2,309	7,452	3,959		5,188	3,444
Changes in operating assets and liabilities:
Deferred revenue	(612)	(17)	(656)	413	(649)	466		462	(38,569)
Other long-term liabilities	(59)	(635)	(46)	(1,571)	(83)	(2,092)		(2,556)	1,042
Net cash used in operating activities	(66,639)	(68,237)	(128,496)	(110,768)	(184,026)	(158,423)		(220,519)	(184,812)
Restatement Adjustment
Condensed Consolidated Statements of Cash Flow
Net loss	(1,264)	1,243	(2,507)	(4,260)	(3,479)	(5,354)		(7,782)	74,954
Non-cash collaboration revenue - related party	(20)	(26)	(34)	(69)	(49)	(87)		(104)	(75,740)
Share of loss from equity method investments	1,242	(1,265)	2,463	4,216	3,414	5,288		7,695	646
Changes in operating assets and liabilities:
Deferred revenue	609	14	653	(430)	646	(485)		(483)	272
Other long-term liabilities	(567)	34	(575)	543	(532)	638		674	(132)
Net cash used in operating activities	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0		$ 0	$ 0

Description of Business and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of Business and Summary of Significant Accounting Policies

Allogene Therapeutics, Inc. (the Company or Allogene) was incorporated on November 30, 2017 in the State of Delaware and is headquartered in South San Francisco, California. Allogene is a clinical-stage immuno-oncology company pioneering the development of genetically engineered allogeneic T cell product candidates for the treatment of cancer. The Company is developing a pipeline of off-the-shelf T cell product candidates that are designed to target and kill cancer cells.

Public Offerings

In November 2019, the Company entered into a sales agreement with Cowen and Company, LLC (Cowen), as amended on November 2, 2022 and November 2, 2023, under which the Company may from time to time issue and sell shares of its common stock through Cowen in at-the-market (ATM) offerings. The aggregate compensation payable to Cowen as the Company's sales agent equals up to 3.0% of the gross sales price of the shares sold through Cowen pursuant to the sales agreement. During the year ended December 31, 2020, the Company sold an aggregate of 848,663 shares of common stock in ATM offerings resulting in net proceeds of $26.2 million. During the year ended December 31, 2023, the Company sold an aggregate of 20,894,565 shares of common stock in ATM offerings resulting in net proceeds of $91.1 million. The specified dollar limit on the amount of common stock that may be sold under the sales agreement was removed pursuant to the November 2, 2023 amendment to the sales agreement.

In June 2020, the Company sold 13,457,447 shares of its common stock, which included 1,755,319 shares sold pursuant to the full exercise of the underwriters' option to purchase additional shares, in an underwritten public offering at a price of $47.00 per share, which resulted in gross proceeds of approximately $632.5 million. Net proceeds to the Company after deducting the underwriting discounts and commissions and other expenses were approximately $595.7 million.

Need for Additional Capital

The Company has sustained operating losses and expects to continue to generate operating losses for the foreseeable future. The Company’s ultimate success depends on the outcome of its research and development activities as well as the ability to commercialize the Company’s product candidates. The Company had cash, cash equivalents and investments of $448.7 million as of December 31, 2023. Since inception through December 31, 2023, the Company has incurred cumulative net losses of $1,562.2 million. Management expects to incur additional losses in the future to fund its operations and conduct product research and development and recognizes the need to raise additional capital to fully implement its business plan.

The Company intends to raise additional capital through the issuance of equity securities, debt financings or other sources in order to further implement its business plan. However, if such financing is not available at adequate levels, the Company will need to reevaluate its operating plan and may be required to delay the development of its product candidates. The Company expects that its cash and cash equivalents and investments will be sufficient to fund its operations for at least the next 12 months from the date the Company’s Annual Report on Form 10-K is filed with the Securities and Exchange Commission (SEC).

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP).

In June 2020, the Company formed a wholly-owned, Netherlands-based subsidiary, Allogene Therapeutics, B.V., to help prepare for and assist with the Company's activities in Europe. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. All material intercompany balances and transactions have been eliminated during consolidation.

Restatement of financial statements

As described further in Note 6 and Note 8, on December 14, 2020, the Company entered into an Exclusive License Agreement (License Agreement) with Allogene Overland Biopharm (CY) Limited (Allogene Overland), a joint venture established by the Company and Overland Pharmaceuticals (CY) Inc. (Overland) pursuant to a Share Purchase Agreement

(Share Purchase Agreement), dated December 14, 2020, for the purpose of developing, manufacturing and commercializing certain allogeneic CAR T cell therapies for patients in greater China, Taiwan, South Korea and Singapore, which resulted in the Company acquiring shares of Allogene Overland’s Seed Preferred Stock (Seed Preferred Shares) representing a 49% ownership interest in exchange for entering into a License Agreement.

In 2023, the Company re-evaluated its application of ASC Topic 606, Revenue from Contracts with Customers (ASC 606) and ASC Topic 323, Investments - Equity Method and Joint ventures (ASC 323) to its License Agreement and Share Purchase Agreement with Allogene Overland. Upon reassessment, the Company has determined the 49% of Allogene Overland's outstanding Seed Preferred Shares received as a partial consideration for the License Agreement should be initially measured at fair value of $79.0 million rather than the zero carryover basis originally attributed to the Seed Preferred Shares. The initial transaction price to determine revenue related to the License Agreement was revised to include the fair value of the Seed Preferred Shares of $79.0 million and was allocated to the identified performance obligations based on their estimated standalone selling price. Additional revisions were made in the year ended December 31, 2020 whereby, on the date when the Seed Preferred Shares were received, the Company recorded as "Other expenses" in its consolidated statements of operations and comprehensive loss the basis difference of $67.5 million between the fair value of the Seed Preferred Shares of $79.0 million and the amount of the Company's underlying equity in net assets of Allogene Overland of $11.5 million and reduced the carrying value of the Seed Preferred Shares to $11.5 million. In the year ended December 31, 2021, the collaboration revenue increased by $75.6 million and the remaining transaction price of $3.4 million will impact subsequent future periods when related performance obligations are satisfied. Further, the Company recorded its share of net losses of Allogene Overland in each reporting period and reduced the carrying value of the Seed Preferred Shares. Refer to the Impact of restatement section below which describes detailed impact of the restatement for all the periods presented.

The error resulted in an understatement of collaboration revenue and other expenses in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2022, 2021 and 2020, and an understatement of deferred revenue and equity method investment in the consolidated balance sheets as of December 31, 2022 and 2021. These annual periods were restated in the Amendment No. 1 to the Annual Report on Form 10-K/A for the year ended December 31, 2022 filed with the Securities and Exchange Commission (the SEC) on March 14, 2024.

The consolidated financial statements (as restated) also include adjustments to correct certain other previously identified misstatements relating to prior periods that the Company had determined to be immaterial, both individually and in aggregate, with a decrease in other expenses of $0.7 million for the year ended December 31, 2021 and an increase in other expenses of $2.0 million for the year ended December 31, 2022 in the consolidated statements of operations and comprehensive loss.

Impact of restatement

See below for reconciliation from the previously reported to the restated amounts in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2022 and 2021, and in the consolidated balance sheets as of December 31, 2022. The previously reported amounts were derived from the Company's Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC on February 28, 2023 (Original Report). These amounts are labeled as "As Previously Reported" in the tables below. The amounts labeled "Restatement Adjustment" represent the effects of this restatement described above.

The following presents a reconciliation of the impacted financial statement line items as previously reported to the restated amounts as of December 31, 2022, and for the years ended December 31, 2022 and 2021 (in thousands, except share and per share data):


	December 31, 2022
Consolidated Balance Sheets	As previously Reported		Restatement Adjustment		As Restated
Equity method investment	$	12,817	$	4,500	$	17,317
Total assets	817,079		4,500		821,579
Deferred revenue	885		(790)		95
Total current liabilities	54,518		(790)		53,728
Other long-term liabilities	1,569		4,278		5,847
Total liabilities	151,209		3,488		154,697
Accumulated deficit	(1,235,980)		1,012		(1,234,968)
Total stockholders' equity	665,870		1,012		666,882
Total liabilities and stockholders' equity	817,079		4,500		821,579


	Year ended December 31, 2022						Year ended December 31, 2021
Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	243	$	(87)	$	156	$	38,489	$	75,600	$	114,089
Operating expenses:
Research and development	256,387		—		256,387		220,176		—		220,176
General and administrative	79,305		—		79,305		74,105		—		74,105
Total operating expenses	335,692		—		335,692		294,281		—		294,281
Loss from operations	(335,449)		(87)		(335,536)		(255,792)		75,600		(180,192)
Other income (expense), net:
Interest and other income, net	4,566		—		4,566		1,714		—		1,714
Other expenses	(1,749)		(7,695)		(9,444)		(2,927)		(646)		(3,573)
Total other income (expense), net	2,817		(7,695)		(4,878)		(1,213)		(646)		(1,859)
Net loss	(332,632)		(7,782)		(340,414)		(257,005)		74,954		(182,051)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	(7,359)		—		(7,359)		(2,835)		—		(2,835)
Net comprehensive loss	(339,991)		(7,782)		(347,773)		(259,840)		74,954		(184,886)
Net loss per share, basic and diluted	(2.32)				(2.38)		(1.89)				(1.34)
Weighted-average number of shares used in computing net loss per share, basic and diluted	143,147,165				143,147,165		135,820,386				135,820,386


	Year ended December 31, 2022						Year ended December 31, 2021
Consolidated Statements of Stockholders' Equity	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(332,632)	$	(7,782)	$	(340,414)	$	(257,005)	$	74,954	$	(182,051)
Accumulated Deficit	(1,235,980)		1,012		(1,234,968)		(903,348)		8,794		(894,554)
Total stockholders' equity	665,870		1,012		666,882		916,406		8,794		925,200


	Year ended December 31, 2022						Year ended December 31, 2021
Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(332,632)	$	(7,782)	$	(340,414)	$	(257,005)	$	74,954	$	(182,051)
Non-cash collaboration revenue - related party	—		(104)		(104)		—		(75,740)		(75,740)
Share of losses from equity method investments	5,188		7,695		12,883		3,444		646		4,090
Changes in operating assets and liabilities:
Deferred revenue	462		(483)		(21)		(38,569)		272		(38,297)
Other long-term liabilities	(2,556)		674		(1,882)		1,042		(132)		910
Net cash used in operating activities	(220,519)		—		(220,519)		(184,812)		—		(184,812)

The remainder of the notes to the Company's consolidated financial statements have been updated and restated, as applicable, to reflect the impacts from the restatement discussed above.

Included in Note 15 of these consolidated financial statements is the impact of restatement on previously issued (i) unaudited condensed balance sheets as of March 31, 2023 and 2022, June 30, 2023 and 2022 and September 30, 2023 and 2022, (ii) unaudited condensed statements of operations and comprehensive loss for the three months ended March 31, 2023 and 2022, three and six months ended June 30, 2023 and 2022, and three and nine months ended September 30, 2023 and 2022, (iii) unaudited condensed statements of cash flows for the three months ended March 31, 2023 and 2022, six months ended June 30, 2023 and 2022 and nine months ended September 30, 2023 and 2022, in each of the Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2023, June 30, 2023 and September 30, 2023.

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include but are not

limited to the fair value of common stock, the fair value of stock options, the fair value of investments, income tax uncertainties, and certain accruals. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances change. Actual results could differ from those estimates.

Concentration of Credit and other Risks and Uncertainties

Financial instruments, which potentially subject the Company to significant concentrations of credit risk, consist primarily of cash and cash equivalents and investments. The primary objectives for the Company’s investment portfolio are the preservation of capital and the maintenance of liquidity. The Company does not enter into any investment transaction for trading or speculative purposes.

The Company’s investment policy limits investments to certain types of instruments such as certificates of deposit, commercial paper, money market instruments, obligations issued by the U.S. government and U.S. government agencies as well as corporate debt securities, and places restrictions on maturities and concentration by type and issuer. The Company maintains cash balances in excess of amounts insured by the FDIC and concentrated within a limited number of financial institutions. The accounts are monitored by management and management believes that the financial institutions are financially sound, and, accordingly, minimal credit risk exists with respect to these financial institutions. As of December 31, 2023 and 2022, the Company has not experienced any significant credit losses in such accounts or investments.

The Company is subject to a number of risks common for early-stage biopharmaceutical companies including, but not limited to, the ability to achieve any clinical or commercial success of its product candidates, ability to obtain regulatory approval of its product candidates, the need for substantial additional financing to achieve its goals, uncertainty of broad adoption of its approved products, if any, by physicians and patients, significant competition, dependency on the Company's contract manufacturing organization, and ability to manufacture.

Segments

Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (CODM) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined it operates in a single operating segment and has one reportable segment.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in bank money market accounts and money market mutual funds.

The Company has issued letters of credit under separate lease and other agreements which have been collateralized by restricted cash. This cash is classified as long-term restricted cash on the accompanying consolidated balance sheets based on the terms of the underlying agreements.

Investments

Investments are available-for-sale and are carried at estimated fair value. The Company’s valuations of marketable securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets. Management determines the appropriate classification of its investments in debt securities at the time of purchase and at the end of each reporting period. Investments with original maturities of less than three months at the date of purchase are classified as cash and cash equivalents. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than twelve months from the consolidated balance sheet date are classified as current.

Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive income. The Company periodically evaluates whether declines in fair values of its available-for-sale securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the available-for-sale security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than

not it will be required to sell any available-for-sale securities before recovery of its amortized cost basis. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest and other income, net. The cost of investments sold is based on the specific-identification method. Interest income on investments is included in interest and other income, net.

Fair Value Measurement

Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3— Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Property and Equipment, Net

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets, generally three to seven years. Maintenance and repairs are charged to operations as incurred. Upon sale or retirement of assets, the cost and related accumulated depreciation are removed from the consolidated balance sheet and the resulting gain or loss is reflected in other expense.

The Company has determined the estimated life of assets to be as follows:


Laboratory equipment			5 years
Computer equipment and purchased software			3 - 5 years
Fixtures and furniture			7 years
Leasehold improvements			Shorter of lease term or useful life

The Company adopted Accounting Standards Update ("ASU") No. 2018-15, Intangibles – Goodwill and other – Internal-Use Software (Subtopic 350-40) on January 1, 2020 on a prospective basis. The Company capitalizes implementation costs associated with internal use cloud computing arrangements in alignment with ASC 350-40 internal-use software. Costs incurred in preliminary project stage and post implementation stage are expensed as incurred. Costs incurred during the application development stage of implementation are capitalized in other long-term assets on the consolidated balance sheet. Capitalized implementation costs from cloud computing arrangements are amortized over the term of the cloud-based service arrangement.

Leases

The Company early adopted ASU No. 2016-2, Leases on January 1, 2018. For its long-term operating leases, the Company recognizes a right-of-use asset and a lease liability on its consolidated balance sheets. The lease liability is determined as the present value of future lease payments using an estimated rate of interest that the Company would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The right-of-use asset is based on the liability adjusted for any prepaid or deferred rent. The lease term at the commencement date is determined by considering whether renewal options and termination options are reasonably assured of exercise.

Rent expense for the operating lease is recognized on a straight-line basis over the lease term and is included in operating expenses on the consolidated statements of operations and comprehensive loss. Variable lease payments include lease operating expenses.

The Company elected to exclude from its consolidated balance sheets recognition of leases having a term of 12 months or less (short-term leases) and elected to not separate lease components and non-lease components for its long-term real-estate leases.

Equity Method Investments

The Company uses the equity method of accounting for equity investments in companies if the investment provides the ability to exercise significant influence, but not control, over operating and financial policies of the investee. The Company's proportionate share of the net income or loss of these companies is included in other expenses in the consolidated statement of operations. Judgment regarding the level of influence over each equity method investment includes considering key factors such as our ownership interest, representation on the board of directors, participation in policy-making decisions and material purchase and sale transactions.

The Company evaluates equity method investments for impairment whenever events or changes in circumstances indicate that the carrying amount of the investment might not be recoverable. Factors considered when reviewing an equity method investment for impairment include the length of time (duration) and the extent (severity) to which the fair value of the equity method investment has been less than cost, the investee’s financial condition and near-term prospects and the intent and ability to hold the investment for a period of time sufficient to allow for anticipated recovery. An impairment that is other-than-temporary is recognized in the period identified.

Variable Interest Entities

For entities in which the Company has variable interests, the Company focuses on identifying if one of the entities is the primary beneficiary through having the power to direct the activities that most significantly impact the variable interest entity’s economic performance and having the obligation to absorb losses or the right to receive benefits from the variable interest entity. If the Company is the primary beneficiary of a variable interest entity, the assets, liabilities, and results of operations of the variable interest entity will be included in the Company’s consolidated financial statements. The Company did not consolidate any variable interest entities in any of the periods presented because the Company determined that it was not the primary beneficiary.

Accrued Research and Development Costs

The Company records accrued liabilities for estimated costs of research and development activities conducted by collaboration partners and third-party service providers, which include the conduct of preclinical studies and clinical trials, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in accrued and other current liabilities on the consolidated balance sheets and within research and development expenses on the consolidated statements of operations and comprehensive loss.

The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its collaboration partners and third-party service providers. The Company makes significant judgments and estimates in determining the accrued liabilities balance at the end of each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception.

Income Taxes

Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Management makes an assessment of the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s historical operating performance and net losses, the net deferred tax assets have been fully offset by a valuation allowance.

The Company recognizes uncertain income tax positions at the largest amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. Changes in recognition or measurement are reflected in the period in which judgment occurs. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of the provision for income taxes.

Stock-Based Compensation

The Company measures its stock-based awards granted to employees, consultants and directors based on the estimated fair values of the awards and recognizes the compensation over the requisite service period. The Company uses the Black-Scholes option-pricing model, the lattice option pricing model or Monte Carlo simulation to estimate the fair value of its stock-based awards. Stock-based compensation is recognized using the straight-line method. As the stock compensation expense is based on awards ultimately expected to vest, it is reduced by forfeitures. The Company accounts for forfeitures as they occur.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive shares of common stock. Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share since the effects of potentially dilutive securities are antidilutive. Shares of common stock subject to repurchase are excluded from the weighted-average shares.

Comprehensive Loss

Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss. For the years ended December 31, 2023, 2022 and 2021 this was comprised of unrealized gains and losses, net of tax, on the Company’s investments.

Impairment of Long-Lived Assets

Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount of an asset group to the future net undiscounted cash flows that the assets are expected to generate. The long-lived assets recoverability test is performed at the asset group level, i.e., the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. If this test indicates that the carrying amount of the asset group is not recoverable, an impairment loss is measured as the amount by which the carrying amount of an asset group exceeds its fair value. Any impairment loss is allocated to the long-lived assets of the group on a pro rata basis using the relative carrying amounts of those assets, except that the carrying amount of an individual asset shall not be reduced below its fair value. The Company recorded long-lived assets impairment loss of $13.2 million for the year ended December 31, 2023 (see Note 5). There were no long-lived assets impairment losses recorded for the years ended December 31, 2022 and December 31, 2021.

Revenue Recognition

The Company’s revenue has been generated through collaboration research and license agreements. The terms of these agreements may contain multiple deliverables which may include (i) grant of licenses, (ii) transfer of know-how, (iii) research and development activities, (iii) clinical manufacturing, and (iv) product supply. The payment terms of these agreements may include nonrefundable upfront fees, payments for research and development activities, payments based upon the achievement of certain milestones, royalty payments based on product sales derived from the collaboration, and payments for supplying product.

The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808, Collaborative Arrangements (ASC 808) to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For collaboration arrangements within the scope of ASC 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be within the scope of ASC 808 and those that are more reflective of a vendor-customer relationship and, therefore, within the scope of Topic 606, Revenue

from Contracts with Customers (ASC 606). For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, generally by analogy to Topic 606.

For elements of those arrangements that the Company determines should be accounted for under ASC 606, the Company assesses which activities in the collaboration agreements are performance obligations that should be accounted for separately and determines the transaction price of the arrangement, which includes the assessment of the probability of achievement of future milestones and other potential consideration. A performance obligation represents a promise in a contract to transfer a distinct good or service to a customer, which represents a unit of accounting in accordance with ASC 606. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. The Company considers a performance obligation satisfied once the Company has transferred control of a good or service to the customer, meaning the customer has the ability to use and obtain the benefit of the good or service. A portion of the consideration should be allocated to each distinct performance obligation. The total consideration which the Company expects to collect in exchange for the Company’s products is an estimate and may be fixed or variable. The Company constrains the estimated variable consideration when it assesses it is probable that a significant reversal in the amount of cumulative revenue recognized may occur in future periods. The transaction price is re-evaluated, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The allocation of the transaction price is performed based on standalone selling prices, which are based on estimated amounts that the Company would charge for a performance obligation if it were sold separately. Revenue is recognized when, or as, performance obligations in the contracts are satisfied, in the amount reflecting the expected consideration to be received from the goods or services transferred to the customers. Funds received in advance are recorded as deferred revenue and are recognized as the related performance obligation is satisfied.

Research and Development Expenses

Research and development costs are expensed as incurred and consist of salaries and benefits, including associated stock-based compensation, and laboratory supplies and facility costs, as well as fees paid to other entities that conduct certain research and development activities on the Company’s behalf. Research and development expenses also include costs incurred for internal and sponsored collaborative research and development activities. Costs associated with co-development activities performed under the various license and collaboration agreements are included in research and development expenses.

Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and then expensed as the related goods are delivered or the services are performed.

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Company follows authoritative accounting guidance, which among other things, defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability.

The Company measures and reports its cash equivalents, restricted cash, and investments at fair value.

Money market funds are measured at fair value on a recurring basis using quoted prices and are classified as Level 1. Investments are measured at fair value based on inputs other than quoted prices that are derived from observable market data and are classified as Level 2 inputs, except for investments in U.S. treasury securities which are classified as Level 1.

There were no Level 3 assets or liabilities at December 31, 2023 or 2022.

Financial assets subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type as of December 31, 2023 are presented in the following table:


	December 31, 2023
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Financial Assets:
Money market funds ¹	$	78,536	$	—	$	—	$	78,536
Corporate bonds	—		97,166		—		97,166
U.S. treasury securities	229,516		—		—		229,516
U.S. agency securities	—		38,860		—		38,860
Total financial assets	$	308,052	$	136,026	$	—	$	444,078

¹ Included within cash and cash equivalents on the Company’s consolidated balance sheet

Financial assets subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type as of December 31, 2022 are presented in the following table:


	December 31, 2022
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Financial Assets:
Money market funds ¹	$	10,679	$	—	$	—	$	10,679
Commercial paper	—		4,954		—		4,954
Corporate bonds	—		153,256		—		153,256
U.S. treasury securities	318,022		—		—		318,022
U.S. agency securities	—		39,416		—		39,416
Total financial assets	$	328,701	$	197,626	$	—	$	526,327

¹ Included within cash and cash equivalents on the Company’s consolidated balance sheet

The carrying amounts of accounts payable and accrued liabilities approximate their fair values due to their short-term maturities. The Company’s Level 2 securities are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly.

There were no transfers of assets between the fair value measurement levels during the years ended December 31, 2023 or 2022.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Description of Business and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Error Corrections and Prior Period Adjustments


	December 31, 2022
Consolidated Balance Sheets	As previously Reported		Restatement Adjustment		As Restated
Equity method investment	$	12,817	$	4,500	$	17,317
Total assets	817,079		4,500		821,579
Deferred revenue	885		(790)		95
Total current liabilities	54,518		(790)		53,728
Other long-term liabilities	1,569		4,278		5,847
Total liabilities	151,209		3,488		154,697
Accumulated deficit	(1,235,980)		1,012		(1,234,968)
Total stockholders' equity	665,870		1,012		666,882
Total liabilities and stockholders' equity	817,079		4,500		821,579


	Year ended December 31, 2022						Year ended December 31, 2021
Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	243	$	(87)	$	156	$	38,489	$	75,600	$	114,089
Operating expenses:
Research and development	256,387		—		256,387		220,176		—		220,176
General and administrative	79,305		—		79,305		74,105		—		74,105
Total operating expenses	335,692		—		335,692		294,281		—		294,281
Loss from operations	(335,449)		(87)		(335,536)		(255,792)		75,600		(180,192)
Other income (expense), net:
Interest and other income, net	4,566		—		4,566		1,714		—		1,714
Other expenses	(1,749)		(7,695)		(9,444)		(2,927)		(646)		(3,573)
Total other income (expense), net	2,817		(7,695)		(4,878)		(1,213)		(646)		(1,859)
Net loss	(332,632)		(7,782)		(340,414)		(257,005)		74,954		(182,051)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	(7,359)		—		(7,359)		(2,835)		—		(2,835)
Net comprehensive loss	(339,991)		(7,782)		(347,773)		(259,840)		74,954		(184,886)
Net loss per share, basic and diluted	(2.32)				(2.38)		(1.89)				(1.34)
Weighted-average number of shares used in computing net loss per share, basic and diluted	143,147,165				143,147,165		135,820,386				135,820,386


	Year ended December 31, 2022						Year ended December 31, 2021
Consolidated Statements of Stockholders' Equity	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(332,632)	$	(7,782)	$	(340,414)	$	(257,005)	$	74,954	$	(182,051)
Accumulated Deficit	(1,235,980)		1,012		(1,234,968)		(903,348)		8,794		(894,554)
Total stockholders' equity	665,870		1,012		666,882		916,406		8,794		925,200


	Year ended December 31, 2022						Year ended December 31, 2021
Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(332,632)	$	(7,782)	$	(340,414)	$	(257,005)	$	74,954	$	(182,051)
Non-cash collaboration revenue - related party	—		(104)		(104)		—		(75,740)		(75,740)
Share of losses from equity method investments	5,188		7,695		12,883		3,444		646		4,090
Changes in operating assets and liabilities:
Deferred revenue	462		(483)		(21)		(38,569)		272		(38,297)
Other long-term liabilities	(2,556)		674		(1,882)		1,042		(132)		910
Net cash used in operating activities	(220,519)		—		(220,519)		(184,812)		—		(184,812)

Estimated Life of Assets

The Company has determined the estimated life of assets to be as follows:


Laboratory equipment			5 years
Computer equipment and purchased software			3 - 5 years
Fixtures and furniture			7 years
Leasehold improvements			Shorter of lease term or useful life

Net Loss and Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Schedule of Earnings Per Share Basic and Diluted

The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except share and per share data):


	Year Ended December 31,
	2023		2022		2021
			(As Restated)		(As Restated)
Numerator:
Net loss	$	(327,265)	$	(340,414)	$	(182,051)
Denominator:
Weighted average common shares outstanding	156,931,778		143,147,165		135,820,386
Net loss per share, basic and diluted	$	(2.09)	$	(2.38)	$	(1.34)

Schedule of Anti-dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share

Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:


	Year Ended December 31,
	2023	2022	2021
Stock options to purchase common stock	21,812,946	17,569,575	10,239,167
Restricted stock units subject to vesting	12,180,471	5,493,406	4,261,108
Expected shares purchased under Employee Stock Purchase Plan	2,168,264	1,092,314	474,966
Founder shares subject to future vesting	—	—	1,514,424
Early exercised stock options subject to future vesting	29,180	138,841	720,321
Total	36,190,861	24,294,136	17,209,986

Investments - Summary of Cash Equivalents, Restricted Cash and Investments, Classified as Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 444,589				$ 535,809
Unrealized Gains	245				30
Unrealized Losses	(756)				(9,512)
Fair Value	444,078				526,327
Cash equivalents	78,536				11,760
Short-term investments	365,542	$ 396,259	$ 337,204	$ 361,293	455,416	$ 477,872	$ 394,451	$ 364,536
Long-term investments	0	$ 32,170	$ 52,586	$ 42,788	59,151	$ 85,108	$ 195,637	$ 284,093
Total cash equivalents, and investments	444,078				526,327
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	78,536				10,679
Unrealized Gains	0				0
Unrealized Losses	0				0
Fair Value	78,536				10,679
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost					4,956
Unrealized Gains					0
Unrealized Losses					(2)
Fair Value					4,954
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	97,265				156,019
Unrealized Gains	113				25
Unrealized Losses	(212)				(2,788)
Fair Value	97,166				153,256
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	229,563				323,077
Unrealized Gains	132				5
Unrealized Losses	(179)				(5,060)
Fair Value	229,516				318,022
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	39,225				41,078
Unrealized Gains	0				0
Unrealized Losses	(365)				(1,662)
Fair Value	$ 38,860				$ 39,416

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2023
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock Pursuant to the Amended and Restated Certificate of Incorporation filed on October 15, 2018, as amended, the Company is authorized to issue a total of 10,000,000 shares of preferred stock, of which no shares were issued and outstanding at December 31, 2023 and 2022. Common Stock Pursuant to the Certificate of Amendment of Amended and Restated Certificate of Incorporation filed on June 17, 2022, the Company is authorized to issue a total of 400,000,000 shares of common stock, of which 168,642,238 and 144,438,304 shares were issued and outstanding at December 31, 2023 and 2022, respectively. Common stockholders are entitled to dividends if and when declared by the Company’s Board of Directors subject to the prior rights of the preferred stockholders. As of December 31, 2023 and 2022, no dividends on common stock had been declared by the Company’s Board of Directors.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Subparagraph (d)
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-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
-Subparagraph (SX 210.3-04)
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-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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-Paragraph 14
-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Fair Value Measurements - Financial Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 444,078,000	$ 526,327,000
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	78,536,000	10,679,000
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets		4,954,000
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	97,166,000	153,256,000
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	229,516,000	318,022,000
U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	38,860,000	39,416,000
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	308,052,000	328,701,000
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	78,536,000	10,679,000
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets		0
Level 1 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 1 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	229,516,000	318,022,000
Level 1 \| U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	136,026,000	197,626,000
Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets		4,954,000
Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	97,166,000	153,256,000
Level 2 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 2 \| U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	38,860,000	39,416,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets		0
Level 3 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 3 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 3 \| U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 0	$ 0

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Restricted stock units subject to vesting - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Restricted Stock Units
Unvested, beginning balance (in shares)	5,493,406
Granted (in shares)	12,119,645
Vested (in shares)	(1,905,294)
Forfeited (in shares)	(3,527,286)
Unvested, ending balance (in shares)	12,180,471	5,493,406
Vested and expected to vest (in shares)	12,180,471
Weighted- Average Grant Date Fair Value per Share
Beginning balance (in dollars per share)	$ 16.86
Granted (in dollars per share)	4.55
Vested (in dollars per share)	17.47
Forfeited (in dollars per share)	9.39
Ending balance (in dollars per share)	6.68	$ 16.86
Vested and expected to vest (in dollars per share)	$ 6.68
Restricted stock units, unvested, weighted average remaining vesting life	2 years	1 year 6 months 14 days
Restricted stock units, granted, weighted average remaining vesting life	1 year 9 months 14 days
Restricted stock units, vested and expected to vest, weighted average remaining vesting life	2 years
Restricted stock units, aggregate intrinsic value, beginning balance	$ 34,554
Restricted stock units, aggregate intrinsic value, ending balance	39,099	$ 34,554
Restricted stock units, aggregate intrinsic value, vested and expected to vest	$ 39,099

Subsequent Events (Details) - Subsequent Event - USD ($) $ in Millions	Jan. 04, 2024	Jan. 03, 2024
Reduction To Workforce
Subsequent Event [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated, Period Percent	22.00%
Restructuring and Related Cost, Expected Cost	$ 2.9
Foresight Collaboration Agreement
Subsequent Event [Line Items]
Committed funding		$ 26.0

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Audit Information [Abstract]
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California

Stock-Based Compensation

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

2018 Equity Incentive Plan

In June 2018, the Company adopted its 2018 Equity Incentive Plan (Prior 2018 Plan). The Prior 2018 Plan provided for the Company to sell or issue common stock or restricted common stock, or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, members of the Company’s Board of Directors and consultants of the Company under terms and provisions established by the Company’s Board of Directors. In September 2018, the Board of Directors adopted a new amended and restated 2018 Equity Incentive Plan as a successor to and continuation of the Prior 2018 Plan, which became effective in October 2018 (the 2018 Plan), which authorized additional shares for issuance and provided for an automatic annual increase to the number of shares issuable under the 2018 Plan by an amount equal to 5% of the total number of shares of common stock outstanding on December 31st of the preceding calendar year. The term of any stock option granted under the 2018 Plan cannot exceed 10 years. The Company generally grants stock-based awards with service conditions only. Options granted typically vest over a four-year period but may be granted with different vesting terms. Restricted Stock Units granted typically vest annually over a four-year period but may be granted with different vesting terms. Options shall not have an exercise price less than 100% of the fair market value of the Company’s common stock on the grant date. If the individual possesses more than 10% of the combined voting power of all classes of stock of the Company, the exercise price shall not be less than 110% of the fair market value of a common share of stock on the date of grant. This requirement is applicable to incentive stock options only.

As of December 31, 2023 and 2022, there were 6,468,650 and 12,932,861 shares reserved by the Company under the 2018 Plan for the future issuance of equity awards.

Stock Option Exchange program

On June 21, 2022, the Company commenced an offer to exchange certain eligible options held by eligible employees of the Company for new options (the Exchange Offer). The Exchange Offer expired on July 19, 2022. Pursuant to the Exchange Offer, 199 eligible holders elected to exchange, and the Company accepted for cancellation, eligible options to purchase an aggregate of 3,666,600 shares of the Company’s common stock, representing approximately 93.5% of the total shares of common stock underlying the eligible options. On July 19, 2022, immediately following the expiration of the Exchange Offer, the Company granted new options to purchase 3,666,600 shares of common stock, pursuant to the terms of the Exchange Offer and the 2018 Plan. The exercise price of the new options granted pursuant to the Exchange Offer was $13.31 per share, which was the closing price of the common stock on the Nasdaq Global Select Market on the grant date of the new options. The new options are subject to a new three-year vesting schedule, vesting in equal annual installments over the vesting term. Each new option has a maximum term of seven years.

The exchange of stock options was treated as a modification for accounting purposes. The incremental expense of $5.2 million for the modified options was calculated using a lattice option pricing model. The incremental expense and the unamortized expense remaining on the exchanged options as of the modification date are being recognized over the new three-year service period.

Stock Option Activity

The following summarizes option activity under the 2018 Plan:


	Outstanding Options
	Number of Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Term	Aggregate Intrinsic Value
				(in years)	(in thousands)
Balance, December 31, 2022	17,569,575	$	12.90	7.73	$	6,658
Options granted	10,315,270	4.94
Options exercised	(850,396)	2.45			$	2,334
Options forfeited	(5,221,503)	11.31
Balance, December 31, 2023	21,812,946	$	9.93	7.53	$	662
Exercisable, December 31, 2023	18,687,724	$	9.98	7.56	$	639
Vested and expected to vest, December 31, 2023	21,812,946	$	9.93	7.53	$	662

The aggregate intrinsic values of options exercised, outstanding, exercisable, vested and expected to vest were calculated as the difference between the exercise price of the options and the closing price of the Company’s common stock on the Nasdaq Global Select Market on December 31, 2023. The aggregate intrinsic value of options exercised during the years ended December 31, 2023, 2022 and 2021 was $2.3 million, $1.9 million and $21.9 million, respectively. During the years ended December 31, 2023, 2022 and 2021, the estimated weighted-average grant-date fair value of employee options granted was $3.33 per share, $9.97 per share and $18.79 per share, respectively. As of December 31, 2023 and 2022, there was $58.1 million and $83.2 million, respectively, of unrecognized stock-based compensation related to unvested stock options, which is expected to be recognized over a weighted-average period of 2.42 years and 2.70 years, respectively.

The fair value of employee, consultant and director stock option awards was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions:


	Year Ended December 31,
	2023	2022
Fair value of common stock	$2.72 - $7.23	$7.08 - $17.28
Expected term in years	5.27 - 6.08	5.25 - 6.08
Expected volatility	73.18% - 74.10%	70.82% - 73.39%
Expected risk-free interest rate	3.45% - 4.61%	1.61% - 4.12%
Expected dividend	0%	0%

The fair value of the new options granted under the Option Exchange program was estimated at the date of grant using a lattice option pricing model with the following assumptions: expected volatility of 73.74%, expected risk-free rate of 3.06%, expected dividends of 0% and expected exercise barrier of 2.57.

The Black-Scholes option-pricing model and the lattice option pricing model require the use of subjective assumptions which determine the fair value of stock-based awards. These assumptions include:

Fair value of common stock—For grants before October 2018 when the Company was private and there was no public market for the Company’s common stock, the fair value of the Company’s common stock underlying share-based awards was estimated on each grant date by the Company’s Board of Directors. In order to determine the fair value of the Company’s common stock underlying option grants, the Company’s Board of Directors considered, among other things, valuations of the Company’s common stock prepared by an unrelated third-party valuation firm in accordance with the guidance provided by the American Institute of Certified Public Accountants Practice Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. For all grants subsequent to the Company’s IPO in October 2018, the fair value of common stock was determined by taking the closing price per share of common stock per Nasdaq.

Expected term— The expected term represents the period that stock-based awards are expected to be outstanding. The expected term for option grants is determined using the simplified method. The simplified method deems the term to be the average of the time-to-vesting and the contractual life of the stock-based awards.

Expected volatility— The Company uses an average historical stock price volatility of comparable public companies within the biotechnology and pharmaceutical industry that were deemed to be representative of future stock price trends as the Company does not have sufficient trading history for its common stock. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Risk-free interest rate—The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of option.

Expected dividend—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Expected exercise barrier - The modified options are assumed to be exercised upon vesting and when the ratio of stock market price to exercise price reaches 2.57, or expiration, whichever is earlier.

For the years ended December 31, 2023, 2022 and 2021, total stock-based compensation expense related to stock options was $34.4 million, $42.2 million and $38.2 million, respectively.

Restricted Stock Unit Activity

The following summarizes restricted stock unit activity under the 2018 Plan:


	Outstanding Restricted Stock Units
	Restricted Stock Units	Weighted- Average Grant Date Fair Value per Share		Weighted Average Remaining Vesting Life	Aggregate Intrinsic Value
				(in years)	(in thousands)
Unvested December 31, 2022	5,493,406	$	16.86	1.54	$	34,554
Granted	12,119,645	4.55		1.79
Vested	(1,905,294)	17.47
Forfeited	(3,527,286)	9.39
Unvested December 31, 2023	12,180,471	$	6.68	2.00	$	39,099
Vested and expected to vest, December 31, 2023	12,180,471	$	6.68	2.00	$	39,099

For the year ended December 31, 2023, the Company granted 3,264,750 performance-based restricted stock units and 2,189,125 restricted stock units with a market condition to certain executive officers and other employees pursuant to the 2018

Plan. These awards are subject to the holders' continuous service to the Company through each applicable vesting event. Through December 31, 2023, the Company believes that the achievement of the requisite performance conditions for these awards are not probable. As a result, no compensation expense has been recognized related to the performance-based restricted stock units in the year ended December 31, 2023. The Company recognized $2.2 million in stock-based compensation expense related to the restricted units with a market condition for the year ended December 31, 2023.

For the years ended December 31, 2023, 2022 and 2021, total stock-based compensation expense related to restricted stock units, performance based restricted stock units and restricted stock units with a market condition was $28.5 million, $34.3 million and $26.6 million, respectively. For the years ended December 31, 2023, 2022 and 2021, total fair value of vested restricted stock units, performance based restricted stock units and restricted stock units with a market condition as of their grant dates was $33.3 million, $32.8 million and $18.5 million, respectively. As of December 31, 2023 and 2022, there was $50.7 million and $70.5 million, respectively, of unrecognized stock-based compensation which is expected to be recognized over a weighted average period of 2.36 years and 2.55 years, respectively.

Employee Stock Purchase Plan

In October 2018, the stockholders approved the 2018 Employee Stock Purchase Plan (ESPP), which initially reserved 1,160,000 shares of the Company's common stock for employee purchases under terms and provisions established by the Board of Directors. Effective January 1, 2023 and 2022, the number of shares authorized under the ESPP for employee purchases increased by 1,444,383 and 1,426,230 shares respectively. The ESPP is intended to qualify as an "employee stock purchase plan" under Section 423 of the Internal Revenue Code. Under the current offering adopted pursuant to the ESPP, each offering period is approximately 24 months, which is generally divided into four purchase periods of approximately six months.

Employees are eligible to participate if they are employed by the Company. Under the ESPP, employees may purchase common stock through payroll deductions at a price equal to 85% of the lower of the fair market value of common stock on the first trading day of each offering period or on the purchase date. The ESPP provides for consecutive, overlapping 24-month offering periods. The offering periods are scheduled to start on the first trading day on or after March 16 or September 16 of each year, except for the first offering period which commenced on October 11, 2018, the first trading day after the effective date of the Company’s registration statement. Contributions under the ESPP are limited to a maximum of 15% of an employee’s eligible compensation.

The fair values of the rights granted under the ESPP were calculated using the following assumptions:


	Year ended December 31,
	2023	2022
Expected term (in years)	0.50 – 2.00	0.50 – 2.00
Volatility	67.32% - 85.05%	74.20% - 85.63%
Risk-free interest rate	4.05%-5.35%	0.86% - 3.88%
Dividend yield	—	—

For the years ended December 31, 2023, 2022 and 2021, total stock-based compensation expense related to ESPP was $3.1 million, $3.6 million and $2.3 million, respectively.

Founders’ Stock

In 2018, the Company’s founders agreed to modify their common shares outstanding to include vesting provisions that require continued service to the Company in order to vest in those shares. Stock-based compensation expense is recognized for shares of founders’ stock as vesting conditions are met. In relation to the modification, 24,230,750 shares of founders’ stock remained unvested at the modification date in April 2018. For the years ended December 31, 2022, and 2021, $3.4 million and $13.7 million of stock-based compensation expense was recognized related to the vesting of 1,514,424, and 6,057,695 shares, respectively, of founders' stock. At December 31, 2022, there was no unrecognized stock-based compensation expense. The weighted-average fair value at grant date for founders’ stock was $2.27 per share.

Stock-based compensation expense

For the years ended December 31, 2023, 2022 and 2021, the Company recorded $66.0 million, $83.6 million and $80.8 million, respectively, of stock-based compensation expense related to stock options, restricted stock units, employee stock purchase plans and vesting of the founders’ common stock as research and development and general and administrative expense in its consolidated statements of operations and comprehensive loss.

Early Exercised Options

The Company allows certain of its employees and its directors to exercise options granted under the Prior 2018 Plan and the 2018 Plan prior to vesting. The shares related to early exercised stock options are subject to the Company’s lapsing repurchase right upon termination of employment or service on the Company’s Board of Directors at the lesser of the original purchase price or fair market value at the time of repurchase. In order to vest, the holders are required to provide continued service to the Company. The proceeds are initially recorded in accrued and other liabilities and other long-term liabilities for the noncurrent portion. The proceeds are reclassified to paid-in capital as the repurchase right lapses. During the years ended December 31, 2023 and 2022, no options were early exercised. As of December 31, 2023 and 2022, there was $0.5 million and $1.9 million, respectively, recorded in accrued and other liabilities and zero and $0.6 million, respectively, recorded in other long-term liabilities related to shares held by employees and directors that were subject to repurchase. The underlying shares are shown as outstanding in the consolidated financial statements since the exercise date but the shares which are subject to future vesting conditions are not included in the calculation of earnings per share.

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in valuation allowance	$ 80,100,000	$ 108,200,000	$ 28,500,000
Tax benefit	0	0	0
Accrued interest and penalties	0	0	0
Accounting Standards Update 2019-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax benefit	$ 0	$ 0	$ 0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

- Definition

Amount of tax expense (benefit) allocated to other comprehensive income (loss).

+ References

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+ Details

Description of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). In June 2020, the Company formed a wholly-owned, Netherlands-based subsidiary, Allogene Therapeutics, B.V., to help prepare for and assist with the Company's activities in Europe. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. All material intercompany balances and transactions have been eliminated during consolidation.
Restatement	Restatement of financial statements As described further in Note 6 and Note 8, on December 14, 2020, the Company entered into an Exclusive License Agreement (License Agreement) with Allogene Overland Biopharm (CY) Limited (Allogene Overland), a joint venture established by the Company and Overland Pharmaceuticals (CY) Inc. (Overland) pursuant to a Share Purchase Agreement (Share Purchase Agreement), dated December 14, 2020, for the purpose of developing, manufacturing and commercializing certain allogeneic CAR T cell therapies for patients in greater China, Taiwan, South Korea and Singapore, which resulted in the Company acquiring shares of Allogene Overland’s Seed Preferred Stock (Seed Preferred Shares) representing a 49% ownership interest in exchange for entering into a License Agreement. In 2023, the Company re-evaluated its application of ASC Topic 606, Revenue from Contracts with Customers (ASC 606) and ASC Topic 323, Investments - Equity Method and Joint ventures (ASC 323) to its License Agreement and Share Purchase Agreement with Allogene Overland. Upon reassessment, the Company has determined the 49% of Allogene Overland's outstanding Seed Preferred Shares received as a partial consideration for the License Agreement should be initially measured at fair value of $79.0 million rather than the zero carryover basis originally attributed to the Seed Preferred Shares. The initial transaction price to determine revenue related to the License Agreement was revised to include the fair value of the Seed Preferred Shares of $79.0 million and was allocated to the identified performance obligations based on their estimated standalone selling price. Additional revisions were made in the year ended December 31, 2020 whereby, on the date when the Seed Preferred Shares were received, the Company recorded as "Other expenses" in its consolidated statements of operations and comprehensive loss the basis difference of $67.5 million between the fair value of the Seed Preferred Shares of $79.0 million and the amount of the Company's underlying equity in net assets of Allogene Overland of $11.5 million and reduced the carrying value of the Seed Preferred Shares to $11.5 million. In the year ended December 31, 2021, the collaboration revenue increased by $75.6 million and the remaining transaction price of $3.4 million will impact subsequent future periods when related performance obligations are satisfied. Further, the Company recorded its share of net losses of Allogene Overland in each reporting period and reduced the carrying value of the Seed Preferred Shares. Refer to the Impact of restatement section below which describes detailed impact of the restatement for all the periods presented. The error resulted in an understatement of collaboration revenue and other expenses in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2022, 2021 and 2020, and an understatement of deferred revenue and equity method investment in the consolidated balance sheets as of December 31, 2022 and 2021. These annual periods were restated in the Amendment No. 1 to the Annual Report on Form 10-K/A for the year ended December 31, 2022 filed with the Securities and Exchange Commission (the SEC) on March 14, 2024. The consolidated financial statements (as restated) also include adjustments to correct certain other previously identified misstatements relating to prior periods that the Company had determined to be immaterial, both individually and in aggregate, with a decrease in other expenses of $0.7 million for the year ended December 31, 2021 and an increase in other expenses of $2.0 million for the year ended December 31, 2022 in the consolidated statements of operations and comprehensive loss. Impact of restatement See below for reconciliation from the previously reported to the restated amounts in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2022 and 2021, and in the consolidated balance sheets as of December 31, 2022. The previously reported amounts were derived from the Company's Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC on February 28, 2023 (Original Report). These amounts are labeled as "As Previously Reported" in the tables below. The amounts labeled "Restatement Adjustment" represent the effects of this restatement described above.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include but are not limited to the fair value of common stock, the fair value of stock options, the fair value of investments, income tax uncertainties, and certain accruals. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances change. Actual results could differ from those estimates.
Concentration of Credit and other Risks and Uncertainties	Concentration of Credit and other Risks and Uncertainties Financial instruments, which potentially subject the Company to significant concentrations of credit risk, consist primarily of cash and cash equivalents and investments. The primary objectives for the Company’s investment portfolio are the preservation of capital and the maintenance of liquidity. The Company does not enter into any investment transaction for trading or speculative purposes. The Company’s investment policy limits investments to certain types of instruments such as certificates of deposit, commercial paper, money market instruments, obligations issued by the U.S. government and U.S. government agencies as well as corporate debt securities, and places restrictions on maturities and concentration by type and issuer. The Company maintains cash balances in excess of amounts insured by the FDIC and concentrated within a limited number of financial institutions. The accounts are monitored by management and management believes that the financial institutions are financially sound, and, accordingly, minimal credit risk exists with respect to these financial institutions. As of December 31, 2023 and 2022, the Company has not experienced any significant credit losses in such accounts or investments. The Company is subject to a number of risks common for early-stage biopharmaceutical companies including, but not limited to, the ability to achieve any clinical or commercial success of its product candidates, ability to obtain regulatory approval of its product candidates, the need for substantial additional financing to achieve its goals, uncertainty of broad adoption of its approved products, if any, by physicians and patients, significant competition, dependency on the Company's contract manufacturing organization, and ability to manufacture.
Segments	Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (CODM) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined it operates in a single operating segment and has one reportable segment.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in bank money market accounts and money market mutual funds. The Company has issued letters of credit under separate lease and other agreements which have been collateralized by restricted cash. This cash is classified as long-term restricted cash on the accompanying consolidated balance sheets based on the terms of the underlying agreements.
Investments	Investments Investments are available-for-sale and are carried at estimated fair value. The Company’s valuations of marketable securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets. Management determines the appropriate classification of its investments in debt securities at the time of purchase and at the end of each reporting period. Investments with original maturities of less than three months at the date of purchase are classified as cash and cash equivalents. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than twelve months from the consolidated balance sheet date are classified as current. Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive income. The Company periodically evaluates whether declines in fair values of its available-for-sale securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the available-for-sale security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any available-for-sale securities before recovery of its amortized cost basis. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest and other income, net. The cost of investments sold is based on the specific-identification method. Interest income on investments is included in interest and other income, net.
Fair Value Measurement	Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3— Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets, generally three to seven years. Maintenance and repairs are charged to operations as incurred. Upon sale or retirement of assets, the cost and related accumulated depreciation are removed from the consolidated balance sheet and the resulting gain or loss is reflected in other expense. The Company adopted Accounting Standards Update ("ASU") No. 2018-15, Intangibles – Goodwill and other – Internal-Use Software (Subtopic 350-40) on January 1, 2020 on a prospective basis. The Company capitalizes implementation costs associated with internal use cloud computing arrangements in alignment with ASC 350-40 internal-use software. Costs incurred in preliminary project stage and post implementation stage are expensed as incurred. Costs incurred during the application development stage of implementation are capitalized in other long-term assets on the consolidated balance sheet. Capitalized implementation costs from cloud computing arrangements are amortized over the term of the cloud-based service arrangement.
Leases	Leases The Company early adopted ASU No. 2016-2, Leases on January 1, 2018. For its long-term operating leases, the Company recognizes a right-of-use asset and a lease liability on its consolidated balance sheets. The lease liability is determined as the present value of future lease payments using an estimated rate of interest that the Company would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The right-of-use asset is based on the liability adjusted for any prepaid or deferred rent. The lease term at the commencement date is determined by considering whether renewal options and termination options are reasonably assured of exercise. Rent expense for the operating lease is recognized on a straight-line basis over the lease term and is included in operating expenses on the consolidated statements of operations and comprehensive loss. Variable lease payments include lease operating expenses. The Company elected to exclude from its consolidated balance sheets recognition of leases having a term of 12 months or less (short-term leases) and elected to not separate lease components and non-lease components for its long-term real-estate leases.
Equity Method Investments	Equity Method Investments The Company uses the equity method of accounting for equity investments in companies if the investment provides the ability to exercise significant influence, but not control, over operating and financial policies of the investee. The Company's proportionate share of the net income or loss of these companies is included in other expenses in the consolidated statement of operations. Judgment regarding the level of influence over each equity method investment includes considering key factors such as our ownership interest, representation on the board of directors, participation in policy-making decisions and material purchase and sale transactions. The Company evaluates equity method investments for impairment whenever events or changes in circumstances indicate that the carrying amount of the investment might not be recoverable. Factors considered when reviewing an equity method investment for impairment include the length of time (duration) and the extent (severity) to which the fair value of the equity method investment has been less than cost, the investee’s financial condition and near-term prospects and the intent and ability to hold the investment for a period of time sufficient to allow for anticipated recovery. An impairment that is other-than-temporary is recognized in the period identified.
Variable Interest Entities	Variable Interest Entities For entities in which the Company has variable interests, the Company focuses on identifying if one of the entities is the primary beneficiary through having the power to direct the activities that most significantly impact the variable interest entity’s economic performance and having the obligation to absorb losses or the right to receive benefits from the variable interest entity. If the Company is the primary beneficiary of a variable interest entity, the assets, liabilities, and results of operations of the variable interest entity will be included in the Company’s consolidated financial statements. The Company did not consolidate any variable interest entities in any of the periods presented because the Company determined that it was not the primary beneficiary.
Accrued Research and Development Costs	Accrued Research and Development Costs The Company records accrued liabilities for estimated costs of research and development activities conducted by collaboration partners and third-party service providers, which include the conduct of preclinical studies and clinical trials, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in accrued and other current liabilities on the consolidated balance sheets and within research and development expenses on the consolidated statements of operations and comprehensive loss. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its collaboration partners and third-party service providers. The Company makes significant judgments and estimates in determining the accrued liabilities balance at the end of each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Management makes an assessment of the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s historical operating performance and net losses, the net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes uncertain income tax positions at the largest amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. Changes in recognition or measurement are reflected in the period in which judgment occurs. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of the provision for income taxes.
Stock-Based Compensation	Stock-Based Compensation The Company measures its stock-based awards granted to employees, consultants and directors based on the estimated fair values of the awards and recognizes the compensation over the requisite service period. The Company uses the Black-Scholes option-pricing model, the lattice option pricing model or Monte Carlo simulation to estimate the fair value of its stock-based awards. Stock-based compensation is recognized using the straight-line method. As the stock compensation expense is based on awards ultimately expected to vest, it is reduced by forfeitures. The Company accounts for forfeitures as they occur.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive shares of common stock. Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share since the effects of potentially dilutive securities are antidilutive. Shares of common stock subject to repurchase are excluded from the weighted-average shares.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss. For the years ended December 31, 2023, 2022 and 2021 this was comprised of unrealized gains and losses, net of tax, on the Company’s investments.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount of an asset group to the future net undiscounted cash flows that the assets are expected to generate. The long-lived assets recoverability test is performed at the asset group level, i.e., the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. If this test indicates that the carrying amount of the asset group is not recoverable, an impairment loss is measured as the amount by which the carrying amount of an asset group exceeds its fair value. Any impairment loss is allocated to the long-lived assets of the group on a pro rata basis using the relative carrying amounts of those assets, except that the carrying amount of an individual asset shall not be reduced below its fair value. The Company recorded long-lived assets impairment loss of $13.2 million for the year ended December 31, 2023 (see Note 5). There were no long-lived assets impairment losses recorded for the years ended December 31, 2022 and December 31, 2021.
Revenue Recognition	Revenue Recognition The Company’s revenue has been generated through collaboration research and license agreements. The terms of these agreements may contain multiple deliverables which may include (i) grant of licenses, (ii) transfer of know-how, (iii) research and development activities, (iii) clinical manufacturing, and (iv) product supply. The payment terms of these agreements may include nonrefundable upfront fees, payments for research and development activities, payments based upon the achievement of certain milestones, royalty payments based on product sales derived from the collaboration, and payments for supplying product. The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808, Collaborative Arrangements (ASC 808) to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For collaboration arrangements within the scope of ASC 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be within the scope of ASC 808 and those that are more reflective of a vendor-customer relationship and, therefore, within the scope of Topic 606, Revenue from Contracts with Customers (ASC 606). For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, generally by analogy to Topic 606. For elements of those arrangements that the Company determines should be accounted for under ASC 606, the Company assesses which activities in the collaboration agreements are performance obligations that should be accounted for separately and determines the transaction price of the arrangement, which includes the assessment of the probability of achievement of future milestones and other potential consideration. A performance obligation represents a promise in a contract to transfer a distinct good or service to a customer, which represents a unit of accounting in accordance with ASC 606. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. The Company considers a performance obligation satisfied once the Company has transferred control of a good or service to the customer, meaning the customer has the ability to use and obtain the benefit of the good or service. A portion of the consideration should be allocated to each distinct performance obligation. The total consideration which the Company expects to collect in exchange for the Company’s products is an estimate and may be fixed or variable. The Company constrains the estimated variable consideration when it assesses it is probable that a significant reversal in the amount of cumulative revenue recognized may occur in future periods. The transaction price is re-evaluated, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The allocation of the transaction price is performed based on standalone selling prices, which are based on estimated amounts that the Company would charge for a performance obligation if it were sold separately. Revenue is recognized when, or as, performance obligations in the contracts are satisfied, in the amount reflecting the expected consideration to be received from the goods or services transferred to the customers. Funds received in advance are recorded as deferred revenue and are recognized as the related performance obligation is satisfied.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred and consist of salaries and benefits, including associated stock-based compensation, and laboratory supplies and facility costs, as well as fees paid to other entities that conduct certain research and development activities on the Company’s behalf. Research and development expenses also include costs incurred for internal and sponsored collaborative research and development activities. Costs associated with co-development activities performed under the various license and collaboration agreements are included in research and development expenses. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and then expensed as the related goods are delivered or the services are performed.
Recently Adopted Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements There have been no new accounting pronouncements issued or effective that are expected to have a material impact on the Company's consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In September 2023, the FASB issued Accounting Standard Update No. 2023-09, Income taxes (Topic 740), Improvement to income tax disclosures, which requires to disclose some additional information in the consolidated financial statements. This standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements.

Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2020		140,474,305
Beginning balance at Dec. 31, 2020	$ 1,013,457	$ 140	$ 1,725,552	$ (712,503)	$ 268
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and vesting of RSUs		1,961,554
Issuance of common stock upon exercise of stock options and vesting of RSUs	8,346	$ 2	8,344
Vesting of early exercised common stock	3,848		3,848
Stock-based compensation	80,818		80,818
Employee stock purchase plan (in shares)		187,206
Employee stock purchase plan	3,617		3,617
Net loss	(182,051)			(182,051)
Net unrealized gain (loss) on available-for-sale investments	(2,835)				(2,835)
Ending balance (in shares) at Dec. 31, 2021		142,623,065
Ending balance at Dec. 31, 2021	925,200	$ 142	1,822,179	(894,554)	(2,567)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(78,607)
Net unrealized gain (loss) on available-for-sale investments	$ (6,682)
Ending balance (in shares) at Mar. 31, 2022	143,569,902
Ending balance at Mar. 31, 2022	$ 865,267
Beginning balance (in shares) at Dec. 31, 2021		142,623,065
Beginning balance at Dec. 31, 2021	925,200	$ 142	1,822,179	(894,554)	(2,567)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(158,897)
Net unrealized gain (loss) on available-for-sale investments	$ (8,905)
Ending balance (in shares) at Jun. 30, 2022	143,723,171
Ending balance at Jun. 30, 2022	$ 806,483
Beginning balance (in shares) at Dec. 31, 2021		142,623,065
Beginning balance at Dec. 31, 2021	925,200	$ 142	1,822,179	(894,554)	(2,567)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(243,139)
Net unrealized gain (loss) on available-for-sale investments	$ (10,391)
Ending balance (in shares) at Sep. 30, 2022	144,031,588
Ending balance at Sep. 30, 2022	$ 743,401
Beginning balance (in shares) at Dec. 31, 2021		142,623,065
Beginning balance at Dec. 31, 2021	925,200	$ 142	1,822,179	(894,554)	(2,567)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and vesting of RSUs		1,453,624
Issuance of common stock upon exercise of stock options and vesting of RSUs	489	$ 2	487
Vesting of early exercised common stock	2,905		2,905
Stock-based compensation	83,600		83,600
Employee stock purchase plan (in shares)		361,615
Employee stock purchase plan	2,461		2,461
Net loss	(340,414)			(340,414)
Net unrealized gain (loss) on available-for-sale investments	$ (7,359)				(7,359)
Ending balance (in shares) at Dec. 31, 2022	144,438,304	144,438,304
Ending balance at Dec. 31, 2022	$ 666,882	$ 144	1,911,632	(1,234,968)	(9,926)
Beginning balance (in shares) at Mar. 31, 2022	143,569,902
Beginning balance at Mar. 31, 2022	$ 865,267
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(80,290)
Net unrealized gain (loss) on available-for-sale investments	$ (2,223)
Ending balance (in shares) at Jun. 30, 2022	143,723,171
Ending balance at Jun. 30, 2022	$ 806,483
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(84,242)
Net unrealized gain (loss) on available-for-sale investments	$ (1,486)
Ending balance (in shares) at Sep. 30, 2022	144,031,588
Ending balance at Sep. 30, 2022	$ 743,401
Beginning balance (in shares) at Dec. 31, 2022	144,438,304	144,438,304
Beginning balance at Dec. 31, 2022	$ 666,882	$ 144	1,911,632	(1,234,968)	(9,926)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(99,968)
Net unrealized gain (loss) on available-for-sale investments	$ 3,992
Ending balance (in shares) at Mar. 31, 2023	145,740,333
Ending balance at Mar. 31, 2023	$ 592,010
Beginning balance (in shares) at Dec. 31, 2022	144,438,304	144,438,304
Beginning balance at Dec. 31, 2022	$ 666,882	$ 144	1,911,632	(1,234,968)	(9,926)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(179,200)
Net unrealized gain (loss) on available-for-sale investments	$ 6,075
Ending balance (in shares) at Jun. 30, 2023	167,133,664
Ending balance at Jun. 30, 2023	$ 621,411
Beginning balance (in shares) at Dec. 31, 2022	144,438,304	144,438,304
Beginning balance at Dec. 31, 2022	$ 666,882	$ 144	1,911,632	(1,234,968)	(9,926)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(241,487)
Net unrealized gain (loss) on available-for-sale investments	$ 7,515
Ending balance (in shares) at Sep. 30, 2023	168,175,221
Ending balance at Sep. 30, 2023	$ 580,635
Beginning balance (in shares) at Dec. 31, 2022	144,438,304	144,438,304
Beginning balance at Dec. 31, 2022	$ 666,882	$ 144	1,911,632	(1,234,968)	(9,926)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from ATM offering, net of commissions and offering costs (in shares)		20,894,565
Issuance of common stock from ATM offering, net of commissions and offering costs	91,112	$ 21	91,091
Issuance of common stock upon exercise of stock options and vesting of RSUs		2,718,410
Issuance of common stock upon exercise of stock options and vesting of RSUs	2,087	$ 3	2,084
Vesting of early exercised common stock	1,999		1,999
Stock-based compensation	65,951		65,951
Employee stock purchase plan (in shares)		590,959
Employee stock purchase plan	2,496		2,495
Net loss	(327,265)			(327,265)
Net unrealized gain (loss) on available-for-sale investments	$ 8,971				8,971
Ending balance (in shares) at Dec. 31, 2023	168,642,238	168,642,238
Ending balance at Dec. 31, 2023	$ 512,233	$ 169	$ 2,075,252	$ (1,562,233)	$ (955)
Beginning balance (in shares) at Mar. 31, 2023	145,740,333
Beginning balance at Mar. 31, 2023	$ 592,010
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(79,232)
Net unrealized gain (loss) on available-for-sale investments	$ 2,083
Ending balance (in shares) at Jun. 30, 2023	167,133,664
Ending balance at Jun. 30, 2023	$ 621,411
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(62,287)
Net unrealized gain (loss) on available-for-sale investments	$ 1,440
Ending balance (in shares) at Sep. 30, 2023	168,175,221
Ending balance at Sep. 30, 2023	$ 580,635

Income Taxes - Summary of Operating Loss Carryforwards and Tax Credits (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Federal \| Indefinite
Operating Loss Carryforwards [Line Items]
Net operating losses carryforwards	$ 707,797
Federal \| 2037
Operating Loss Carryforwards [Line Items]
Net operating losses carryforwards	2
Federal \| 2038-2043
Operating Loss Carryforwards [Line Items]
Tax credits	26,383
State \| Indefinite
Operating Loss Carryforwards [Line Items]
Tax credits	20,856
State \| 2037-2043
Operating Loss Carryforwards [Line Items]
Net operating losses carryforwards	895,132
State \| 2026 -2028
Operating Loss Carryforwards [Line Items]
Tax credits	$ 9,000

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par or stated value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0	0	0	0	0	0	0
Preferred stock, shares outstanding (in shares)	0	0	0	0	0	0	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	400,000,000	200,000,000
Common stock, shares issued (in shares)	168,642,238	168,175,221	167,133,664	145,740,333	144,438,304	144,031,588	143,723,171	143,569,902
Common stock, shares outstanding (in shares)	168,642,238	168,175,221	167,133,664	145,740,333	144,438,304	144,031,588	143,723,171	143,569,902

Description of Business and Summary of Significant Accounting Policies - Additional Information (Details)		1 Months Ended	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended				73 Months Ended
	Oct. 01, 2018	Jun. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2023 USD ($) segment shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2023 USD ($)	Dec. 14, 2020 USD ($)	Nov. 30, 2019
Subsidiary, Sale of Stock [Line Items]
Stock issuance, maximum compensation due to third party (as a percentage of stock sales)																			3.00%
Stock issued, value		$ 595,700,000											$ 91,112,000
Shares sold in transaction (in shares) \| shares		13,457,447
Sale of stock, consideration received on transaction		$ 632,500,000
Common stock price (in dollars per share) \| $ / shares		$ 47.00
Common stock forward split ratio	0.1905
Cash and cash equivalents and marketable securities													448,700,000				$ 448,700,000
Net loss			$ 62,287,000	$ 79,232,000	$ 99,968,000	$ 84,242,000	$ 80,290,000	$ 78,607,000	$ 179,200,000	$ 158,897,000	$ 241,487,000	$ 243,139,000	327,265,000	$ 340,414,000	$ 182,051,000		1,562,200,000
Share of loss from equity method investments					(2,935,000)			(2,535,000)	(5,370,000)	(6,525,000)	(10,866,000)	(9,247,000)	(10,672,000)	(12,883,000)	(4,090,000)
Revenue recognized			22,000	22,000	30,000	27,000	64,000	39,000	52,000	103,000	74,000	130,000	95,000	156,000	114,089,000
Other income (expense)			(5,496,000)	(2,470,000)	(2,935,000)	(2,733,000)	(3,989,000)	915,000	(5,405,000)	(3,074,000)	(10,901,000)	(5,807,000)	$ (17,835,000)	(9,444,000)	(3,573,000)
Reportable segments \| segment													1
Impairment of long-lived asset													$ 13,245,000	0	0
Restatement Adjustment
Subsidiary, Sale of Stock [Line Items]
Net loss			972,000	1,243,000	1,264,000	1,094,000	5,503,000	(1,243,000)	2,507,000	4,260,000	3,479,000	5,354,000		7,782,000	(74,954,000)
Share of loss from equity method investments					(1,242,000)			1,265,000	(2,463,000)	(4,216,000)	(3,414,000)	(5,288,000)		(7,695,000)	(646,000)
Revenue recognized			(21,000)	(22,000)	(22,000)	(22,000)	(22,000)	(22,000)	(44,000)	(44,000)	(65,000)	(66,000)		(87,000)	75,600,000
Other income (expense)			$ (951,000)	$ (1,221,000)	$ (1,242,000)	$ (1,072,000)	$ (5,481,000)	$ 1,265,000	$ (2,463,000)	$ (4,216,000)	$ (3,414,000)	$ (5,288,000)		(7,695,000)	(646,000)
Restatement Adjustment \| Previously Identified Immaterial Misstatements
Subsidiary, Sale of Stock [Line Items]
Other income (expense)														(2,000,000)	700,000
Allogene Overland, Allogene Overland BioPharm (HK) Limited
Subsidiary, Sale of Stock [Line Items]
Revenue recognized													100,000	200,000	114,100,000
Allogene Overland
Subsidiary, Sale of Stock [Line Items]
Ownership percentage																		49.00%
Equity method investments													0	4,500,000			$ 0
Share of loss from equity method investments													$ (4,500,000)	$ (5,700,000)	(1,300,000)	$ (67,500,000)
Allogene Overland \| Allogene Overland, Allogene Overland BioPharm (HK) Limited \| Joint Venture
Subsidiary, Sale of Stock [Line Items]
Fair value																		$ 79,000,000
Equity method investments																11,500,000		$ 0
Underlying equity in net assets																$ 11,500,000
Remaining performance obligation, amount															$ 3,400,000
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Shares sold in transaction (in shares) \| shares		1,755,319
ATM offering
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock (in shares) \| shares																848,663
Stock issued, value																$ 26,200,000
Shares sold in transaction (in shares) \| shares													20,894,565
Sale of stock, consideration received on transaction													$ 91,100,000

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

The Company has incurred net operating losses for all the periods presented. The Company has not reflected any benefit of such net operating loss carryforwards in the accompanying consolidated financial statements.

The Company has established a full valuation allowance against its deferred tax assets due to the uncertainty surrounding the realization of such assets.

Reconciliation of the benefit for income taxes calculated at the statutory rate to our benefit for income taxes is as follows:


	Year Ended December 31,
	2023		2022		2021
			(As Restated)		(As Restated)
	(in thousands)
Tax benefit at federal statutory rate	$	(68,725)	$	(71,487)	$	(38,231)
State taxes, net of federal benefit	(21,610)		(40,642)		8,731
Stock-based compensation	11,132		8,619		4,534
Research tax credits	(3,873)		(4,274)		(2,942)
Change in valuation allowance	82,526		106,111		27,889
Other	550		1,673		19
Benefit for incomes taxes	$	—	$	—	$	—

Deferred income taxes reflect the net tax effects of (a) temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, and (b) operating losses and tax credit carryforwards.

Significant components of our deferred tax assets and liabilities are as follows:


	Year Ended December 31,
	2023		2022		2021
			(As Restated)		(As Restated)
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	211,124	$	174,222	$	144,133
Tax credit carryforwards	32,826		24,517		15,595
Intangibles	14,524		16,966		14,092
Accrued expenses	3,039		4,227		3,091
Lease liabilities	26,358		28,298		15,724
Stock based compensation	25,350		25,731		14,693
Investments	28,735		26,291		15,849
Capitalized R&D	73,492		41,273		—
Other	2,189		1,741		1,076
Total deferred tax assets	417,637		343,266		224,253
Deferred tax liabilities:
Fixed assets	—		—		(250)
Right of use leased assets	(17,652)		(23,392)		(12,478)
Other	(301)		(244)		(68)
Total deferred tax liabilities	(17,953)		(23,636)		(12,796)
Net deferred tax assets	399,684		319,630		211,457
Valuation allowance	(399,684)		(319,630)		(211,457)
Net deferred tax assets	$	—	$	—	$	—

Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Due to the lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by approximately $80.1 million, $108.2 million and $28.5 million during the years ended December 31, 2023, 2022 and 2021, respectively.

The following table sets forth the Company's federal and state NOL carryforwards and federal research and development tax credits as of December 31, 2023:


	Amount		Expiration
	(in thousands)
Net operating losses, federal	$	707,797	Indefinite
Net operating losses, federal	$	2	2037
Net operating losses, state	$	895,132	2037-2043
Tax credits, federal	$	26,383	2038-2043
Tax credits, state	$	20,856	Indefinite
California Competes Tax credits, state	$	9,000	2026 -2028

Current federal and California tax laws include substantial restrictions on the utilization of NOLs and tax credit carryforwards in the event of an ownership change of a corporation. Accordingly, the Company's ability to utilize NOLs and tax credit carryforwards may be limited as a result of such ownership changes. Such a limitation could result in the expiration of carryforwards before they are utilized.

In December 2019, the FASB issued Accounting Standards Update No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12), which simplifies the accounting for income taxes, eliminates certain exceptions within ASC 740, Income Taxes, and clarifies certain aspects of the current guidance to promote consistency among reporting entities. This guidance was effective for the Company in the first quarter of 2021 on a prospective basis, and early adoption was permitted. The Company early adopted this standard as of January 1, 2020 on a prospective basis in

accordance with ASC 250, Accounting Changes and Error Corrections. The adoption resulted in the Company no longer needing to determine the tax effect from unrealized gains on available for sale securities, which previously had been disclosed in the consolidated statement of operations as a benefit from income taxes. The impact of the adoption is that the benefit from income taxes in the consolidated statement of operations and comprehensive loss is zero. For the years ended December 31, 2023, 2022 and 2021, the Company recorded a tax benefit of zero.

We apply the provisions of ASC Topic 740 to account for uncertain income tax positions. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
	2023		2022		2021
	(in thousands)
Balance at beginning of the year:	$	14,570	$	9,798	$	6,161
Additions based on tax positions related to current year	4,325		4,772		3,637
Additions to tax position of prior year	—		—		—
Reductions to tax position of prior years	—		—		—
Lapse of the applicable statute of limitations	—		—		—
Balance at end of the year	$	18,895	$	14,570	$	9,798

It is the Company’s policy to include penalties and interest expense related to income taxes as a component of interest and other income, net, as necessary. As of December 31, 2023, 2022 and 2021, there were no accrued interest and penalties related to uncertain tax positions. The reversal of the uncertain tax benefits would not affect the effective tax rate to the extent that the Company continues to maintain a full valuation allowance against its deferred tax assets. Unrecognized tax benefits may change during the next 12 months for items that arise in the ordinary course of business. We are subject to examination by U.S. federal or state tax authorities for all years since inception.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
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-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 2
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Income Taxes - Schedule of Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of the year	$ 14,570	$ 9,798	$ 6,161
Additions based on tax positions related to current year	4,325	4,772	3,637
Additions to tax position of prior year	0	0	0
Reductions to tax position of prior years	0	0	0
Lapse of the applicable statute of limitations	0	0	0
Balance at end of the year	$ 18,895	$ 14,570	$ 9,798

Recent Accounting Guidance	12 Months Ended
Recent Accounting Guidance	Dec. 31, 2023
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Guidance	Recent Accounting Guidance Recently Adopted Accounting Pronouncements There have been no new accounting pronouncements issued or effective that are expected to have a material impact on the Company's consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In September 2023, the FASB issued Accounting Standard Update No. 2023-09, Income taxes (Topic 740), Improvement to income tax disclosures, which requires to disclose some additional information in the consolidated financial statements. This standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(i)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (g)(2)(iii)
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
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+ Details

Income Taxes - Schedule of Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	$ (68,725)	$ (71,487)	$ (38,231)
State taxes, net of federal benefit	(21,610)	(40,642)	8,731
Stock-based compensation	11,132	8,619	4,534
Research tax credits	(3,873)	(4,274)	(2,942)
Change in valuation allowance	82,526	106,111	27,889
Other	550	1,673	19
Benefit for incomes taxes	$ 0	$ 0	$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Pfizer Inc. PF Equity Holdings 2 B.V. held 22,032,040 shares of Common Stock based on the Schedule 13D/A filed on September 17, 2021 with the SEC. According to the Schedule 13D/A filing, PF Equity Holdings 2 B.V. is a wholly-owned subsidiary of Pfizer formed for the purpose of holding certain assets owned or controlled by Pfizer or its direct or indirect subsidiaries. Based on a Form 4 filed on April 4, 2022 by PF Equity Holdings 2 B.V., Pfizer held the 22,032,040 shares as of March 31, 2022. Collaboration Revenue and Equity Method Investment (As Restated) In December 2020, the Company entered into the License Agreement with Allogene Overland, a corporate joint venture entity and related party (see Note 6). The License Agreement was subsequently assigned to a wholly owned subsidiary of Allogene Overland, Allogene Overland HK. On April 1, 2022, Allogene Overland HK assigned the License Agreement to Allogene Overland Biopharm (PRC) Co., Limited. During the years ended December 31, 2023, 2022 and 2021, the Company recognized $0.1 million, $0.2 million and $114.1 million, respectively, of collaboration revenue under this arrangement. For the year ended December 31, 2023, 2022 and 2021, the Company recorded zero, $0.7 million and $0.2 million, respectively, of net cost recoveries under the terms of the license agreement as a reduction to research and development expenses. For the years ended December 31, 2023, 2022 and 2021, the Company recorded $4.5 million, $5.7 million and $1.3 million, respectively, of its share of Allogene Overland's net loss as other expenses (see Note 8). Consulting Agreements In June 2018, the Company entered into a services agreement with Two River Consulting LLC (Two River) a firm affiliated with the Company’s President and Chief Executive Officer, the Company’s Executive Chair of the board of directors, and a director of the Company to provide various managerial, clinical development, administrative, accounting and financial services to the Company. The costs incurred for services provided under this agreement were $0.3 million, $0.7 million and $0.6 million for the years ended December 31, 2023, 2022 and 2021, respectively. In December 2023, the service agreement between the Company and Two River was terminated. In August 2018, the Company entered into a consulting agreement with Bellco Capital LLC (Bellco). Pursuant to the consulting agreement, Bellco provides certain services for the Company, which are performed by Dr. Belldegrun, the Company's executive chair, and include without limitation, providing advice and analysis with respect to the Company’s business, business strategy and potential opportunities in the field of allogeneic CAR T cell therapy and any other aspect of the CAR T cell therapy business as the Company may agree. In consideration for these services, the Company paid Bellco $38,583 per month in arrears commencing January 2021, and $40,217 per month in arrears commencing January 2022. The Company may also, at its discretion, pay Bellco an annual performance award in an amount up to 60% of the aggregate compensation payable to Bellco in a calendar year. The Company also reimburses Bellco for out of pocket expenses incurred in performing the services. The costs incurred for services provided, bonus and out-of-pocket expenses incurred under this consulting agreement were $0.9 million, $0.8 million and $0.7 million for the years ended December 31, 2023, 2022 and 2021, respectively. As of December 31, 2023 and 2022, amounts due to Bellco of $0.2 million and $0.3 million, respectively, were recorded in accrued and other current liabilities in the accompanying consolidated balance sheets. Sublease Agreements In December 2018, the Company entered into a sublease with Bellco for 1,293 square feet of office space in Los Angeles, California for a three year term. On April 1, 2020, Bellco Capital Advisors Inc. assumed all rights, title, interests and obligations under the sublease from Bellco Capital LLC. In November 2021, the sublease was extended to June 30, 2025. The sublease was amended, effective in July 2022, to move to a nearby location, with office space of 737 square feet. The Company’s executive chair, Arie Belldegrun, M.D., FACS, is a trustee of the Belldegrun Family Trust, which controls Bellco Capital Advisors Inc. The total right of use asset and associated liability recorded related to this related party lease was $0.1 million and $0.2 million at December 31, 2023 and 2022, respectively. In February 2023, the Company subleased an additional 2,030 square feet of office space in Los Angeles, California, from Bellco. The sublease term is 115 months, subject to certain early termination rights. The sublease is expected to commence January 1, 2024. The Company paid approximately $0.2 million towards the monthly base rent due for the first month of the sublease term and its share of the security deposit. The total estimated amount of base rent is $2.9 million, subject to rent abatement. The Company also expects to contribute to certain tenant improvements to the space totaling to its share of the total tenant contribution.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-URI https://asc.fasb.org//1943274/2147480990/946-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-URI https://asc.fasb.org//1943274/2147480990/946-20-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
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-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

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-URI https://asc.fasb.org//850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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-Section 50
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

+ Details

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 3, 2024, the Company entered into a Strategic Collaboration Agreement (the Foresight Agreement) with Foresight Diagnostics, Inc. (Foresight Diagnostics). Pursuant to the Foresight Agreement, the parties have agreed to collaborate on a non-exclusive basis in the development of Foresight Diagnostics' minimal residual disease (MRD) assay as an in vitro diagnostic to identify the MRD+ patient population to be enrolled in the Company's planned ALPHA3 trial of cemacabtagene ansegedleucel (known as ALLO-501A), or cema-cel, for treatment of large B cell lymphoma. Under the Foresight Agreement, the Company has agreed to use its commercially reasonable efforts to obtain regulatory approval of cema-cel, and Foresight Diagnostics has agreed to use its commercially reasonable efforts to obtain regulatory approval of an MRD assay for use as an in vitro diagnostic with cema-cel. The Company has agreed to fund approximately $26.0 million in MRD assay development costs, milestone payments for regulatory submissions and assay utilization to process clinical samples. On January 25, 2024, the Company entered into an Amended and Restated Collaboration and License Agreement (the Amended Notch Agreement) with Notch. The Amended Notch Agreement amends and restates the Notch Agreement, dated as of November 1, 2019. Under the Amended Notch Agreement, the Company has relinquished its exclusive rights to all original CAR targets (the Released Targets) except for one CAR target, and has agreed to limit its option right to only one additional CAR target. If the option is exercised, the Company will have a minimum funding commitment for the overall development program. If Notch subsequently out-licenses any of the Released Targets, the Company will be entitled to receive a percentage of upfront and/or milestone payments associated therewith up to a set cap, and will be entitled to a low, single-digit royalty on net sales of products containing a Released Target. In addition, with respect to the Company’s previous equity investments in Notch, the Amended Notch Agreement grants the Company certain anti-dilution protections up to certain limits for certain pre-IPO equity financings. On January 4, 2024, the Company’s Board of Directors approved a reduction in the Company’s workforce of approximately 22% of the Company’s employees in connection with the Company’s pipeline prioritization and clinical development strategy. The reduction in workforce was substantially completed by the end of January 2024. The Company estimates that it will incur charges of approximately $2.9 million for severance payments and employee benefits, primarily in the first quarter of 2024.

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 150,562				$ 149,724
Less: accumulated depreciation	(51,084)				(36,885)
Total property and equipment, net	99,478	$ 102,826	$ 106,386	$ 109,849	112,839	$ 114,442	$ 117,216	$ 120,200
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	108,621				108,550
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	33,157				32,601
Computer equipment and purchased software
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	4,663				4,533
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	4,121				4,012
Construction in progress
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 0				$ 28

Related Party Transactions (Details)	1 Months Ended				3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
Related Party Transactions (Details)	Feb. 28, 2023 USD ($) ft²	Jul. 31, 2022 ft²	Dec. 31, 2018 ft²	Aug. 31, 2018 USD ($)	Sep. 30, 2023 USD ($) shares	Jun. 30, 2023 USD ($) shares	Mar. 31, 2023 USD ($) shares	Sep. 30, 2022 USD ($) shares	Jun. 30, 2022 USD ($) shares	Mar. 31, 2022 USD ($) shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2022 USD ($) shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 17, 2021 shares	Oct. 31, 2018
Related Party Transaction [Line Items]
Common stock, shares outstanding (in shares) \| shares					168,175,221	167,133,664	145,740,333	144,031,588	143,723,171	143,569,902	167,133,664	143,723,171	168,175,221	144,031,588	168,642,238	144,438,304
Revenue recognized					$ 22,000	$ 22,000	$ 30,000	$ 27,000	$ 64,000	$ 39,000	$ 52,000	$ 103,000	$ 74,000	$ 130,000	$ 95,000	$ 156,000	$ 114,089,000
Share of loss from equity method investments							2,935,000			2,535,000	5,370,000	6,525,000	10,866,000	9,247,000	10,672,000	12,883,000	4,090,000
Accrued and other current liabilities					31,195,000	44,263,000	44,624,000	36,938,000	34,360,000	27,763,000	44,263,000	34,360,000	31,195,000	36,938,000	31,096,000	39,743,000
Operating lease term (in months)				127 months																124 months
Operating lease right-of-use asset					$ 78,643,000	$ 80,314,000	$ 81,964,000	$ 85,245,000	$ 86,837,000	$ 57,057,000	$ 80,314,000	$ 86,837,000	$ 78,643,000	$ 85,245,000	63,703,000	83,592,000
Base rent and security deposit, payment	$ 200,000
Total estimated base rent	$ 2,900,000
Allogene Overland
Related Party Transaction [Line Items]
Share of loss from equity method investments															4,500,000	5,700,000	1,300,000	$ 67,500,000
Allogene Overland, Allogene Overland BioPharm (HK) Limited
Related Party Transaction [Line Items]
Revenue recognized															100,000	200,000	114,100,000
Reduction to research and development expense															0	700,000	200,000
Pfizer
Related Party Transaction [Line Items]
Common stock, shares outstanding (in shares) \| shares										22,032,040									22,032,040
Bellco \| Los Angeles California
Related Party Transaction [Line Items]
Area of office space (in square feet) \| ft²			1,293
Operating lease term (in months)			3 years
Operating lease right-of-use asset															100,000	200,000
Bellco \| Consulting agreements \| Maximum
Related Party Transaction [Line Items]
Related party transaction compensation percentage				60.00%
Bellco \| Consulting agreements \| Payments Commencing January 2021
Related Party Transaction [Line Items]
Related party transaction monthly payment in arrears				$ 38,583
Bellco \| Consulting agreements \| Payments Commencing January2022
Related Party Transaction [Line Items]
Related party transaction monthly payment in arrears				$ 40,217
Bellco \| Sublease Agreement
Related Party Transaction [Line Items]
Area of office space (in square feet) \| ft²		737
Related Party \| Bellco
Related Party Transaction [Line Items]
Accrued and other current liabilities															200,000	300,000
Related Party \| Two River Consulting LLC \| Two River Consulting
Related Party Transaction [Line Items]
Cost of revenue															300,000	700,000	600,000
Related Party \| Consulting agreements \| Bellco
Related Party Transaction [Line Items]
Cost of revenue															$ 900,000	$ 800,000	$ 700,000
Related Party \| Sublease Agreement \| Bellco
Related Party Transaction [Line Items]
Area of office space (in square feet) \| ft²	2,030
Sublease, term of contract (in years)	115 months

Equity Method Investments	12 Months Ended
Equity Method Investments	Dec. 31, 2023
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments (As Restated)	Equity Method Investments (As Restated) Notch Therapeutics In conjunction with the execution of the Notch Agreement (see Note 6), the Company also entered into a Share Purchase Agreement with the Company acquiring shares of Notch’s Series Seed convertible preferred stock for a total investment cost of $5.1 million which includes transaction costs of $0.1 million, resulting in a 25% ownership interest in Notch. In February 2021, the Company made a $15.9 million investment in Notch's Series A preferred stock. Immediately following this transaction, the Company's share in Notch was 20.7% on a voting interest basis. In October 2021, the Company made an additional $1.8 million investment in Notch's common stock. Immediately following this transaction, the Company's share in Notch was 23.0% on a voting interest basis. The Company’s total equity investment in Notch as of December 31, 2023 and 2022 was $3.6 million and $12.8 million, respectively, and the Company accounted for the investment using the equity method of accounting. During the years ended December 31, 2023, 2022 and 2021, the Company recognized its share of Notch's net loss of $6.2 million, $7.2 million and $2.7 million, respectively, under the other expenses caption within the consolidated statement of operations. For the year ended December 31, 2023, the Company recorded $3.0 million in other expenses as impairment loss on its equity method investment in Notch. Zero impairment loss was recorded for the years ended December 31, 2022 and 2021. Allogene Overland Biopharm (CY) Limited In conjunction with the execution of the License Agreement with Allogene Overland (see Note 6), the Company also entered into the Share Purchase Agreement and a Shareholders' Agreement with the joint venture company acquiring shares of Allogene Overland’s Seed Preferred Stock representing a 49% ownership interest in exchange for entering into a License Agreement. The Company's total equity investment in Allogene Overland as of December 31, 2023 and 2022 was zero and $4.5 million, respectively, and the Company accounted for the investment using the equity method of accounting. During the years ended December 31, 2023, 2022 and 2021, the Company recognized its share of Allogene Overland's net loss of $4.5 million, $5.7 million, and $1.3 million, respectively, under the other expenses caption within the consolidated statement of operations.

Stock-Based Compensation - Additional Information (Details)		1 Months Ended	12 Months Ended
	Jul. 19, 2022 USD ($) $ / shares shares	Oct. 31, 2018 number_of_periods shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Jun. 21, 2022 employee shares	Apr. 30, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares as percentage of common shares outstanding			5.00%
Number of shares reserved for future issuance (in shares) \| shares			6,468,650	12,932,861
Plan modification, incremental cost	$ 5,200,000
Expected dividend			0.00%
Fair value of common stock (in dollars per share) \| $ / shares			$ 2.57
Total stock-based compensation			$ 66,000,000	$ 83,600,000	$ 80,800,000
Accrued and other liabilities, related to shares held by employees and directors that were subject to repurchase			$ 500,000	$ 1,900,000
Stock options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term (in years)	3 years		4 years
Exchange offer, number of employees \| employee						199
Exchange offer, number of options accepted for cancellation (in shares) \| shares						3,666,600
Exchange offer, percentage of total shares outstanding						0.935
Options granted (in shares) \| shares	3,666,600
Weighted average exercise price (in dollars per share) \| $ / shares	$ 13.31
Expiration period (in years)	7 years
Estimated weighted average grant date fair value of employee options granted (in dollars per share) \| $ / shares			$ 3.33	$ 9.97	$ 18.79
Unrecognized stock based compensation			$ 58,100,000	$ 83,200,000
Period of recognized compensation cost			2 years 5 months 1 day	2 years 8 months 12 days
Expected volatility (in percent)			73.74%
Expected risk-free rate (in percent)			3.06%
Expected dividend			0.00%
Fair value of common stock (in dollars per share) \| $ / shares			$ 2.57
Total stock-based compensation			$ 34,400,000	$ 42,200,000	$ 38,200,000
Restricted stock units subject to vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term (in years)			4 years
Unrecognized stock based compensation			$ 50,700,000	$ 70,500,000
Period of recognized compensation cost			2 years 4 months 9 days	2 years 6 months 18 days
Total stock-based compensation			$ 28,500,000	$ 34,300,000	26,600,000
Fair value of vested restricted stock units and performance based restricted units			$ 33,300,000	$ 32,800,000	18,500,000
Granted (in shares) \| shares			12,119,645
Granted (in dollars per share) \| $ / shares			$ 4.55
Performance Based Restricted Stock Units \| Certain Executive Officers And Other Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation			$ 0
Granted (in shares) \| shares			3,264,750
Restricted Stock Units (RSUs) With Market Condition \| Certain Executive Officers And Other Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation			$ 2,200,000
Granted (in shares) \| shares			2,189,125
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend			0.00%	0.00%
Total stock-based compensation			$ 3,100,000	$ 3,600,000	2,300,000
Initially reserved common stock for employee purchase (in shares) \| shares		1,160,000	1,444,383	1,426,230
Current offering period		24 months
Number of purchase periods \| number_of_periods		4
Purchase period		6 months
Purchase of common stock through payroll deductions to equal price of lower fair market value (in percent)		85.00%
Eligible compensation contribution by employee (in percent)		15.00%
Founders Stock Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock based compensation			$ 0
Total stock-based compensation				$ 3,400,000	$ 13,700,000
Number of vested shares (in shares) \| shares				1,514,424	6,057,695
Granted (in dollars per share) \| $ / shares			$ 2.27
Founders Stock Award \| Founders
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares unvested (in shares) \| shares							24,230,750
Early Exercised Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock for exercise of stock options (in shares) \| shares			0	0
Other long term liabilities, related to shares held by employees and directors that were subject to repurchase			$ 0	$ 600,000
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares) \| shares			10,315,270
Weighted average exercise price (in dollars per share) \| $ / shares			$ 9.93	$ 12.90
Aggregate intrinsic value, exercised			$ 2,334,000	$ 1,900,000	$ 21,900,000
Issuance of common stock for exercise of stock options (in shares) \| shares			850,396
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted period (in years)			10 years
Option exercise price as percentage of fair value of common stock on grate date			100.00%
Option exercise price as percentage of fair value of common stock on grate date			110.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Combined voting power by individual (in percent)			10.00%

Net Loss and Net Loss Per Share - Schedule of Earnings Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended			73 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Numerator:
Net loss	$ (62,287)	$ (79,232)	$ (99,968)	$ (84,242)	$ (80,290)	$ (78,607)	$ (179,200)	$ (158,897)	$ (241,487)	$ (243,139)	$ (327,265)	$ (340,414)	$ (182,051)	$ (1,562,200)
Denominator:
Weighted average common shares outstanding, diluted (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386
Weighted average common shares outstanding, basic (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386
Net loss per share, basic (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)
Net loss per share, diluted (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Description of Business and Summary of Significant Accounting Policies - Schedule of Estimated Life of Assets (Details)	Dec. 31, 2023
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	7 years
Laboratory equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Computer equipment and purchased software \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Computer equipment and purchased software \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Fixtures and furniture
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	7 years

Equity Method Investments (As Restated) (Details) - USD ($)		1 Months Ended		3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Nov. 01, 2019	Oct. 31, 2021	Feb. 28, 2021	Mar. 31, 2023	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 14, 2020
Schedule of Equity Method Investments [Line Items]
Payments for additional investment in interest										$ 0	$ 0	$ 17,710,000
Equity method investments				$ 14,381,000	$ 27,663,000	$ 11,946,000	$ 23,673,000	$ 6,450,000	$ 20,951,000	3,645,000	17,317,000
Share of loss from equity method investments				$ (2,935,000)	$ (2,535,000)	$ (5,370,000)	$ (6,525,000)	$ (10,866,000)	$ (9,247,000)	(10,672,000)	(12,883,000)	(4,090,000)
Impairment loss on equity method investment										7,000,000	0	0
Notch Therapeutics, Inc.
Schedule of Equity Method Investments [Line Items]
Payments to acquire interest in Notch										5,100,000
Transaction costs	$ 100,000
Ownership percentage	25.00%
Payments for additional investment in interest		$ 1,800,000	$ 15,900,000
Equity method investments	$ 5,000,000									3,600,000	12,800,000
Share of loss from equity method investments										(6,200,000)	(7,200,000)	(2,700,000)
Impairment loss on equity method investment										3,000,000	0	0
Notch Therapeutics, Inc. \| Voting Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage		23.00%	20.70%
Allogene
Schedule of Equity Method Investments [Line Items]
Ownership percentage														49.00%
Allogene Overland
Schedule of Equity Method Investments [Line Items]
Ownership percentage														49.00%
Share of loss from equity method investments										(4,500,000)	(5,700,000)	$ (1,300,000)	$ (67,500,000)
Equity method investments										$ 0	$ 4,500,000

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2023

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

The following tables present selected quarterly financial data for 2023 and 2022 (in thousands, except share and per share data):


	March 31, 2023						March 31, 2022
Condensed Consolidated Balance Sheets	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Assets
Current assets:
Cash and cash equivalents	$	109,931	$	—	$	109,931	$	84,514	$	—	$	84,514
Short-term investments	361,293		—		361,293		364,536		—		364,536
Prepaid expenses and other current assets	10,241		—		10,241		20,694		—		20,694
Total current assets	481,465		—		481,465		469,744		—		469,744
Long-term investments	42,788		—		42,788		284,093		—		284,093
Operating lease right-of-use asset	81,964		—		81,964		57,057		—		57,057
Property and equipment, net	109,849		—		109,849		120,200		—		120,200
Restricted cash	10,292		—		10,292		10,292		—		10,292
Other long-term assets	9,389		—		9,389		9,042		—		9,042
Equity method investments	11,124		3,257		14,381		14,204		13,459		27,663
Total assets	746,871		3,257		750,128		964,632		13,459		978,091
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	14,688		—		14,688		8,708		—		8,708
Accrued and other current liabilities	44,624		—		44,624		27,763		—		27,763
Deferred revenue	273		(187)		86		406		(259)		147
Total current liabilities	59,585		(187)		59,398		36,877		(259)		36,618
Lease liability, noncurrent	93,514		—		93,514		69,035		—		69,035
Other long-term liabilities	1,510		3,695		5,205		3,490		3,681		7,171
Total liabilities	154,609		3,509		158,118		109,402		3,421		112,823
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 authorized as of March 31, 2023 and March 31, 2022; no shares were issued and outstanding as of March 31, 2023 and March 31, 2022	—		—		—		—		—		—
Common stock, $0.001 par value: 400,000,000 and 200,000,000 shares authorized as of March 31, 2023 and March 31, 2022, respectively; 145,740,333 and 143,569,902 shares issued and outstanding as of March 31, 2023 and March 31, 2022, respectively	146		—		146		143		—		143
Additional paid-in capital	1,932,734		—		1,932,734		1,847,534		—		1,847,534
Accumulated deficit	(1,334,684)		(252)		(1,334,936)		(983,198)		10,037		(973,161)
Accumulated other comprehensive loss	(5,934)		—		(5,934)		(9,249)		—		(9,249)
Total stockholders’ equity (deficit)	592,262		(252)		592,010		855,230		10,037		865,267
Total liabilities and stockholders’ equity	746,871		3,257		750,128		964,632		13,459		978,091


	Three Months ended March 31, 2023						Three Months ended March 31, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	52	$	(22)	$	30	$	61	$	(22)	$	39
Operating expenses:
Research and development	80,238		—		80,238		60,156		—		60,156
General and administrative	18,884		—		18,884		19,897		—		19,897
Total operating expenses	99,122		—		99,122		80,053		—		80,053
Loss from operations	(99,070)		(22)		(99,092)		(79,992)		(22)		(80,014)
Other income (expense), net:
Interest and other income, net	2,059		—		2,059		492		—		492
Other expenses	(1,693)		(1,242)		(2,935)		(350)		1,265		915
Total other income (expense), net	366		(1,242)		(876)		142		1,265		1,407
Net loss	(98,704)		(1,264)		(99,968)		(79,850)		1,243		(78,607)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	3,992		—		3,992		(6,682)		—		(6,682)
Net comprehensive loss	(94,712)		(1,264)		(95,976)		(86,532)		1,243		(85,289)
Net loss per share, basic and diluted	(0.68)				(0.69)		(0.56)				(0.56)
Weighted-average number of shares used in computing net loss per share, basic and diluted	144,563,829				144,563,829		141,356,306				141,356,306


	Three Months ended March 31, 2023						Three Months ended March 31, 2022
Condensed Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(98,704)	$	(1,264)	$	(99,968)	$	(79,850)	$	1,243	$	(78,607)
Non-cash collaboration revenue - related party	—		(20)		(20)		—		(26)		(26)
Share of losses from equity method investments	1,693		1,242		2,935		3,800		(1,265)		2,535
Changes in operating assets and liabilities:
Deferred revenue	(612)		609		(3)		(17)		14		(3)
Other long-term liabilities	(59)		(567)		(626)		(635)		34		(601)
Net cash used in operating activities	(66,639)		—		(66,639)		(68,237)		—		(68,237)


	June 30, 2023						June 30, 2022
Condensed Consolidated Balance Sheets	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Assets
Current assets:
Cash and cash equivalents	$	154,758	$	—	$	154,758	$	96,041	$	—	$	96,041
Short-term investments	337,204		—		337,204		394,451		—		394,451
Prepaid expenses and other current assets	10,139		—		10,139		22,536		—		22,536
Total current assets	502,101		—		502,101		513,028		—		513,028
Long-term investments	52,586		—		52,586		195,637		—		195,637
Operating lease right-of-use asset	80,314		—		80,314		86,837		—		86,837
Property and equipment, net	106,386		—		106,386		117,216		—		117,216
Restricted cash	10,292		—		10,292		10,292		—		10,292
Other long-term assets	9,382		—		9,382		8,938		—		8,938
Equity method investments	9,910		2,036		11,946		15,696		7,977		23,673
Total assets	770,971		2,036		773,007		947,644		7,977		955,621
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	10,229		—		10,229		9,713		—		9,713
Accrued and other current liabilities	44,263		—		44,263		34,360		—		34,360
Deferred revenue	229		(143)		86		836		(732)		104
Total current liabilities	54,721		(143)		54,578		44,909		(732)		44,177
Lease liability, noncurrent	91,821		—		91,821		98,232		—		98,232
Other long-term liabilities	1,523		3,674		5,197		2,554		4,175		6,729
Total liabilities	148,065		3,531		151,596		145,695		3,443		149,138
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 authorized as of June 30, 2023 and June 30, 2022; no shares were issued and outstanding as of June 30, 2023 and June 30, 2022	—		—		—		—		—		—
Common stock, $0.001 par value: 400,000,000 shares authorized as of June 30, 2023 and June 30, 2022; 167,133,664 and 143,723,171 shares issued and outstanding as of June 30, 2023 and June 30, 2022, respectively	167		—		167		144		—		144
Additional paid-in capital	2,039,263		—		2,039,263		1,871,262		—		1,871,262
Accumulated deficit	(1,412,673)		(1,495)		(1,414,168)		(1,057,985)		4,534		(1,053,451)
Accumulated other comprehensive loss	(3,851)		—		(3,851)		(11,472)		—		(11,472)
Total stockholders’ equity (deficit)	622,906		(1,495)		621,411		801,949		4,534		806,483
Total liabilities and stockholders’ equity	770,971		2,036		773,007		947,644		7,977		955,621


	Three Months ended June 30, 2023						Three Months ended June 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	44	$	(22)	$	22	$	86	$	(22)	$	64
Operating expenses:
Research and development	62,038		—		62,038		57,171		—		57,171
General and administrative	18,524		—		18,524		19,509		—		19,509
Total operating expenses	80,562		—		80,562		76,680		—		76,680
Loss from operations	(80,518)		(22)		(80,540)		(76,594)		(22)		(76,616)
Other income (expense), net:
Interest and other income, net	3,778		—		3,778		315		—		315
Other expenses	(1,249)		(1,221)		(2,470)		1,492		(5,481)		(3,989)
Total other income (expense), net	2,529		(1,221)		1,308		1,807		(5,481)		(3,674)
Net loss	(77,989)		(1,243)		(79,232)		(74,787)		(5,503)		(80,290)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	2,083		—		2,083		(2,223)		—		(2,223)
Net comprehensive loss	(75,906)		(1,243)		(77,149)		(77,010)		(5,503)		(82,513)
Net loss per share, basic and diluted	(0.53)				(0.54)		(0.52)				(0.56)
Weighted-average number of shares used in computing net loss per share, basic and diluted	146,795,826				146,795,826		143,385,045				143,385,045


	Six Months ended June 30, 2023						Six Months ended June 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	96	$	(44)	$	52	$	147	$	(44)	$	103
Operating expenses:
Research and development	142,276		—		142,276		117,327		—		117,327
General and administrative	37,408		—		37,408		39,406		—		39,406
Total operating expenses	179,684		—		179,684		156,733		—		156,733
Loss from operations	(179,588)		(44)		(179,632)		(156,586)		(44)		(156,630)
Other income (expense), net:
Interest and other income, net	5,837		—		5,837		807		—		807
Other expenses	(2,942)		(2,463)		(5,405)		1,142		(4,216)		(3,074)
Total other income (expense), net	2,895		(2,463)		432		1,949		(4,216)		(2,267)
Net loss	(176,693)		(2,507)		(179,200)		(154,637)		(4,260)		(158,897)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	6,075		—		6,075		(8,905)		—		(8,905)
Net comprehensive loss	(170,618)		(2,507)		(173,125)		(163,542)		(4,260)		(167,802)
Net loss per share, basic and diluted	(1.21)				(1.23)		(1.09)				(1.12)
Weighted-average number of shares used in computing net loss per share, basic and diluted	145,685,993				145,685,993		142,376,280				142,376,280


	Six Months ended June 30, 2023						Six Months ended June 30, 2022
Condensed Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(176,693)	$	(2,507)	$	(179,200)	$	(154,637)	$	(4,260)	$	(158,897)
Non-cash collaboration revenue - related party	—		(34)		(34)		—		(69)		(69)
Share of losses from equity method investments	2,907		2,463		5,370		2,309		4,216		6,525
Changes in operating assets and liabilities:
Deferred revenue	(656)		653		(3)		413		(430)		(17)
Other long-term liabilities	(46)		(575)		(621)		(1,571)		543		(1,028)
Net cash used in operating activities	(128,496)		—		(128,496)		(110,768)		—		(110,768)


	September 30, 2023						September 30, 2022
Condensed Consolidated Balance Sheets	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Assets
Current assets:
Cash and cash equivalents	$	69,246	$	—	$	69,246	$	74,357	$	—	$	74,357
Short-term investments	396,259		—		396,259		477,872		—		477,872
Prepaid expenses and other current assets	7,949		—		7,949		16,832		—		16,832
Total current assets	473,454		—		473,454		569,061		—		569,061
Long-term investments	32,170		—		32,170		85,108		—		85,108
Operating lease right-of-use asset	78,643		—		78,643		85,245		—		85,245
Property and equipment, net	102,826		—		102,826		114,442		—		114,442
Restricted cash	10,292		—		10,292		10,292		—		10,292
Other long-term assets	9,576		—		9,576		9,378		—		9,378
Equity method investments	5,365		1,085		6,450		14,046		6,905		20,951
Total assets	712,326		1,085		713,411		887,572		6,905		894,477
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	6,205		—		6,205		11,045		—		11,045
Accrued and other current liabilities	31,195		—		31,195		36,938		—		36,938
Deferred revenue	236		(150)		86		889		(790)		99
Total current liabilities	37,636		(150)		37,486		48,872		(790)		48,082
Lease liability, noncurrent	90,102		—		90,102		96,706		—		96,706
Other long-term liabilities	1,486		3,702		5,188		2,033		4,255		6,288
Total liabilities	129,224		3,552		132,776		147,611		3,465		151,076
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 authorized as of September 30, 2023 and September 30, 2022; no shares were issued and outstanding as of September 30, 2023 and September 30, 2022	—		—		—		—		—		—
Common stock, $0.001 par value: 400,000,000 shares authorized as of September 30, 2023 and September 30, 2022; 168,175,221 and 144,031,588 shares issued and outstanding as of September 30, 2023 and September 30, 2022, respectively	168		—		168		144		—		144
Additional paid-in capital	2,059,333		—		2,059,333		1,893,908		—		1,893,908
Accumulated deficit	(1,473,988)		(2,467)		(1,476,455)		(1,141,133)		3,440		(1,137,693)
Accumulated other comprehensive loss	(2,411)		—		(2,411)		(12,958)		—		(12,958)
Total stockholders’ equity (deficit)	583,102		(2,467)		580,635		739,961		3,440		743,401
Total liabilities and stockholders’ equity	712,326		1,085		713,411		887,572		6,905		894,477


	Three Months ended September 30, 2023						Three Months ended September 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	43	$	(21)	$	22	$	49	$	(22)	$	27
Operating expenses:
Research and development	45,977		—		45,977		63,641		—		63,641
General and administrative	17,041		—		17,041		18,897		—		18,897
Total operating expenses	63,018		—		63,018		82,538		—		82,538
Loss from operations	(62,975)		(21)		(62,996)		(82,489)		(22)		(82,511)
Other income (expense), net:
Interest and other income, net	6,205		—		6,205		1,002		—		1,002
Other expenses	(4,545)		(951)		(5,496)		(1,661)		(1,072)		(2,733)
Total other income (expense), net	1,660		(951)		709		(659)		(1,072)		(1,731)
Net loss	(61,315)		(972)		(62,287)		(83,148)		(1,094)		(84,242)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	1,440		—		1,440		(1,486)		—		(1,486)
Net comprehensive loss	(59,875)		(972)		(60,847)		(84,634)		(1,094)		(85,728)
Net loss per share, basic and diluted	(0.37)				(0.37)		(0.58)				(0.59)
Weighted-average number of shares used in computing net loss per share, basic and diluted	167,649,010				167,649,010		143,661,721				143,661,721


	Nine Months ended September 30, 2023						Nine Months ended September 30, 2022
Condensed Consolidated Statements of Operations and Comprehensive Loss	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Collaboration revenue - related party	$	139	$	(65)	$	74	$	196	$	(66)	$	130
Operating expenses:
Research and development	188,253		—		188,253		180,968		—		180,968
General and administrative	54,449		—		54,449		58,303		—		58,303
Total operating expenses	242,702		—		242,702		239,271		—		239,271
Loss from operations	(242,563)		(65)		(242,628)		(239,075)		(66)		(239,141)
Other income (expense), net:
Interest and other income, net	12,042		—		12,042		1,809		—		1,809
Other expenses	(7,487)		(3,414)		(10,901)		(519)		(5,288)		(5,807)
Total other income (expense), net	4,555		(3,414)		1,141		1,290		(5,288)		(3,998)
Net loss	(238,008)		(3,479)		(241,487)		(237,785)		(5,354)		(243,139)
Other comprehensive income:
Net unrealized (loss) gain on available-for-sale investments, net of tax	7,515		—		7,515		(10,391)		—		(10,391)
Net comprehensive loss	(230,493)		(3,479)		(233,972)		(248,176)		(5,354)		(253,530)
Net loss per share, basic and diluted	(1.55)				(1.58)		(1.67)				(1.70)
Weighted-average number of shares used in computing net loss per share, basic and diluted	153,087,449				153,087,449		142,809,469				142,809,469


	Nine Months ended September 30, 2023						Nine Months ended September 30, 2022
Condensed Consolidated Statements of Cash Flow	As Previously Reported		Restatement Adjustment		As Restated		As Previously Reported		Restatement Adjustment		As Restated
Net Loss	$	(238,008)	$	(3,479)	$	(241,487)	$	(237,785)	$	(5,354)	$	(243,139)
Non-cash collaboration revenue - related party	—		(49)		(49)		—		(87)		(87)
Share of losses from equity method investments	7,452		3,414		10,866		3,959		5,288		9,247
Changes in operating assets and liabilities:
Deferred revenue	(649)		646		(3)		466		(485)		(19)
Other long-term liabilities	(83)		(532)		(615)		(2,092)		638		(1,454)
Net cash used in operating activities	(184,026)		—		(184,026)		(158,423)		—		(158,423)

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 83,155	$ 61,904
Short-term investments	365,542	455,416
Prepaid expenses and other current assets	10,418	11,504
Total current assets	459,115	528,824
Long-term investments	0	59,151
Operating lease right-of-use asset	63,703	83,592
Property and equipment, net	99,478	112,839
Restricted cash	10,292	10,292
Other long-term assets	6,604	9,564
Equity method investments	3,645	17,317
Total assets	642,837	821,579
Current liabilities:
Accounts payable	5,897	13,890
Accrued and other current liabilities	31,096	39,743
Deferred revenue	86	95
Total current liabilities	37,079	53,728
Lease liability, noncurrent	88,346	95,122
Other long-term liabilities	5,179	5,847
Total liabilities	130,604	154,697
Commitments and Contingencies (Notes 6 and 7)
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 authorized as of December 31, 2023 and December 31, 2022; no shares were issued and outstanding as of December 31, 2023 and December 31, 2022	0	0
Common stock, $0.001 par value: 400,000,000 shares authorized as of December 31, 2023 and December 31, 2022; 168,642,238 and 144,438,304 shares issued and outstanding as of December 31, 2023 and December 31, 2022, respectively	169	144
Additional paid-in capital	2,075,252	1,911,632
Accumulated deficit	(1,562,233)	(1,234,968)
Accumulated other comprehensive loss	(955)	(9,926)
Total stockholders’ equity	512,233	666,882
Total liabilities and stockholders’ equity	$ 642,837	$ 821,579
Common stock, shares authorized (in shares)	400,000,000	400,000,000

Cover Page - USD ($) $ in Millions	12 Months Ended
Cover Page - USD ($) $ in Millions	Dec. 31, 2023	Mar. 12, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38693
Entity Registrant Name	Allogene Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-3562771
Entity Address, Address Line One	210 East Grand Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	457-2700
Title of 12(b) Security	Common Stock, Par Value $0.001 Per Share
Trading Symbol	ALLO
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	true
Document Financial Statement Restatement Recovery Analysis [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 557
Entity Common Stock, Shares Outstanding (in shares)		169,091,992
Documents Incorporated by Reference	Portions of the Registrant’s Definitive Proxy Statement relating to the 2024 Annual Meeting of Stockholders, which will be filed with the Securities and Exchange Commission on or before April 29, 2024, are incorporated by reference into Part III of this Annual Report.
Amendment Flag	false
Entity Central Index Key	0001737287
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY

Description of Business and Summary of Significant Accounting Policies - Reconciliation of Restated Financial Statements - Statements of Operations and Comprehensive Loss (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended			73 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Condensed Consolidated Statements of Operations and Comprehensive Loss
Revenue recognized	$ 22	$ 22	$ 30	$ 27	$ 64	$ 39	$ 52	$ 103	$ 74	$ 130	$ 95	$ 156	$ 114,089
Operating expenses:
Research and development	45,977	62,038	80,238	63,641	57,171	60,156	142,276	117,327	188,253	180,968	242,914	256,387	220,176
General and administrative	17,041	18,524	18,884	18,897	19,509	19,897	37,408	39,406	54,449	58,303	71,673	79,305	74,105
Total operating expenses	63,018	80,562	99,122	82,538	76,680	80,053	179,684	156,733	242,702	239,271	327,832	335,692	294,281
Loss from operations	(62,996)	(80,540)	(99,092)	(82,511)	(76,616)	(80,014)	(179,632)	(156,630)	(242,628)	(239,141)	(327,737)	(335,536)	(180,192)
Other income (expense), net:
Interest and other income, net	6,205	3,778	2,059	1,002	315	492	5,837	807	12,042	1,809	18,307	4,566	1,714
Other expenses	(5,496)	(2,470)	(2,935)	(2,733)	(3,989)	915	(5,405)	(3,074)	(10,901)	(5,807)	(17,835)	(9,444)	(3,573)
Total other income (expense), net	709	1,308	(876)	(1,731)	(3,674)	1,407	432	(2,267)	1,141	(3,998)	472	(4,878)	(1,859)
Net loss	(62,287)	(79,232)	(99,968)	(84,242)	(80,290)	(78,607)	(179,200)	(158,897)	(241,487)	(243,139)	(327,265)	(340,414)	(182,051)	$ (1,562,200)
Other comprehensive income:
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, Tax												(7,359)	(2,835)
Net comprehensive loss	$ (60,847)	$ (77,149)	$ (95,976)	$ (85,728)	$ (82,513)	$ (85,289)	$ (173,125)	$ (167,802)	$ (233,972)	$ (253,530)	$ (318,294)	$ (347,773)	$ (184,886)
Net loss per share, diluted (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)
Net loss per share, basic (in dollars per share)	$ (0.37)	$ (0.54)	$ (0.69)	$ (0.59)	$ (0.56)	$ (0.56)	$ (1.23)	$ (1.12)	$ (1.58)	$ (1.70)	$ (2.09)	$ (2.38)	$ (1.34)
Weighted-average number of shares used in computing net loss per share, diluted (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386
Weighted-average number of shares used in computing net loss per share, basic (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469	156,931,778	143,147,165	135,820,386
As Previously Reported
Condensed Consolidated Statements of Operations and Comprehensive Loss
Revenue recognized	$ 43	$ 44	$ 52	$ 49	$ 86	$ 61	$ 96	$ 147	$ 139	$ 196		$ 243	$ 38,489
Operating expenses:
Research and development	45,977	62,038	80,238	63,641	57,171	60,156	142,276	117,327	188,253	180,968		256,387	220,176
General and administrative	17,041	18,524	18,884	18,897	19,509	19,897	37,408	39,406	54,449	58,303		79,305	74,105
Total operating expenses	63,018	80,562	99,122	82,538	76,680	80,053	179,684	156,733	242,702	239,271		335,692	294,281
Loss from operations	(62,975)	(80,518)	(99,070)	(82,489)	(76,594)	(79,992)	(179,588)	(156,586)	(242,563)	(239,075)		(335,449)	(255,792)
Other income (expense), net:
Interest and other income, net	6,205	3,778	2,059	1,002	315	492	5,837	807	12,042	1,809		4,566	1,714
Other expenses	(4,545)	(1,249)	(1,693)	(1,661)	1,492	(350)	(2,942)	1,142	(7,487)	(519)		(1,749)	(2,927)
Total other income (expense), net	1,660	2,529	366	(659)	1,807	142	2,895	1,949	4,555	1,290		2,817	(1,213)
Net loss	(61,315)	(77,989)	(98,704)	(83,148)	(74,787)	(79,850)	(176,693)	(154,637)	(238,008)	(237,785)		(332,632)	(257,005)
Other comprehensive income:
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, Tax												(7,359)	(2,835)
Net comprehensive loss	$ (59,875)	$ (75,906)	$ (94,712)	$ (84,634)	$ (77,010)	$ (86,532)	$ (170,618)	$ (163,542)	$ (230,493)	$ (248,176)		$ (339,991)	$ (259,840)
Net loss per share, diluted (in dollars per share)	$ (0.37)	$ (0.53)	$ (0.68)	$ (0.58)	$ (0.52)	$ (0.56)	$ (1.21)	$ (1.09)	$ (1.55)	$ (1.67)		$ (2.32)	$ (1.89)
Net loss per share, basic (in dollars per share)	$ (0.37)	$ (0.53)	$ (0.68)	$ (0.58)	$ (0.52)	$ (0.56)	$ (1.21)	$ (1.09)	$ (1.55)	$ (1.67)		$ (2.32)	$ (1.89)
Weighted-average number of shares used in computing net loss per share, diluted (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469		143,147,165	135,820,386
Weighted-average number of shares used in computing net loss per share, basic (in shares)	167,649,010	146,795,826	144,563,829	143,661,721	143,385,045	141,356,306	145,685,993	142,376,280	153,087,449	142,809,469		143,147,165	135,820,386
Restatement Adjustment
Condensed Consolidated Statements of Operations and Comprehensive Loss
Revenue recognized	$ (21)	$ (22)	$ (22)	$ (22)	$ (22)	$ (22)	$ (44)	$ (44)	$ (65)	$ (66)		$ (87)	$ 75,600
Operating expenses:
Research and development	0	0	0	0	0	0	0	0	0	0		0	0
General and administrative	0	0	0	0	0	0	0	0	0	0		0	0
Total operating expenses	0	0	0	0	0	0	0	0	0	0		0	0
Loss from operations	(21)	(22)	(22)	(22)	(22)	(22)	(44)	(44)	(65)	(66)		(87)	75,600
Other income (expense), net:
Interest and other income, net	0	0	0	0	0	0	0	0	0	0		0	0
Other expenses	(951)	(1,221)	(1,242)	(1,072)	(5,481)	1,265	(2,463)	(4,216)	(3,414)	(5,288)		(7,695)	(646)
Total other income (expense), net	(951)	(1,221)	(1,242)	(1,072)	(5,481)	1,265	(2,463)	(4,216)	(3,414)	(5,288)		(7,695)	(646)
Net loss	(972)	(1,243)	(1,264)	(1,094)	(5,503)	1,243	(2,507)	(4,260)	(3,479)	(5,354)		(7,782)	74,954
Other comprehensive income:
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, Tax												0	0
Net comprehensive loss	$ (972)	$ (1,243)	$ (1,264)	$ (1,094)	$ (5,503)	$ 1,243	$ (2,507)	$ (4,260)	$ (3,479)	$ (5,354)		$ (7,782)	$ 74,954

Balance Sheet Components

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Balance Sheet Components

Property and Equipment, Net


	December 31,
	2023		2022
	(in thousands)
Leasehold improvements	$	108,621	$	108,550
Laboratory equipment	33,157		32,601
Computer equipment and purchased software	4,663		4,533
Furniture and fixtures	4,121		4,012
Construction in progress	—		28
Total	150,562		149,724
Less: accumulated depreciation	(51,084)		(36,885)
Total property and equipment, net	$	99,478	$	112,839

Depreciation expense for the years ended December 31, 2023, 2022 and 2021 was $14.2 million, $14.3 million and $10.5 million, respectively. Disposals of property and equipment were less than $0.1 million for the years ended December 31, 2023 and 2022. Disposals of property and equipment were zero for the year ended December 31, 2021.

To date, the Company has not recorded any impairment loss on its Property and Equipment. The Company continues to monitor its long-lived assets, including Property and Equipment, for events or changes in circumstances which indicate that the carrying amount of its long-lived assets may not be recoverable.

In December 2023, the Company made a decision to sublease one of its leased buildings in South San Francisco. The Company vacated and ceased occupancy of this building in December 2023 and currently the Company is actively marketing the leased building for sublease. The Company determined that the change in how this property is being used could indicate impairment. The Company has determined it operates in a single operating segment and has one reportable segment. The Company identified two asset groups for purposes of long-lived asset impairment assessment: to be sublet property and

remaining operating segment. The Company concluded that the carrying value of the sublet property asset group was not recoverable and the estimated fair value of this asset group was below its carrying value. The lower fair value of the sublet property asset group was mainly due to the lower estimated sublease income compared to the lease payments in accordance with the initial operating lease agreement and higher discount rate. The Company applied a discounted cash flow method to estimate fair value of its right-of-use asset. It represents level 3 non-recurring fair value measurement. Based on this analysis, the Company concluded the fair value of the right-of-use asset of $13.8 million was lower than its net book value of $27.0 million. The key inputs to this valuation were expected sublease rental income of $22.7 million through March 31, 2032 and annual discount rate of 9%. The Company recognized pre-tax long-lived asset impairment charge of $13.2 million on the right-of-use asset.

Accrued Liabilities

Accrued liabilities consist of the following:


	December 31,
	2023		2022
	(in thousands)
Accrued compensation and related benefits	$	12,665	$	17,935
Accrued research and development expenses	9,315		11,790
Accrued lease liability	6,775		6,002
Unvested shares liability	532		1,898
Other	1,809		2,118
Total accrued and other current liabilities	$	31,096	$	39,743

Commitments and Contingencies - Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 12,711	$ 11,664	$ 7,513
Variable lease cost	3,102	2,139	1,629
Total lease costs	$ 15,813	$ 13,803	$ 9,142

Investment (Tables)

12 Months Ended

Dec. 31, 2023

Investments, All Other Investments [Abstract]

Schedule of Available For Sale Debt Investments by Contractual Maturity

The fair value and amortized cost of cash equivalents and available-for-sale securities by major security type as of December 31, 2023 are presented in the following table:


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	78,536	$	—	$	—	$	78,536
Corporate bonds	97,265		113		(212)		97,166
U.S. treasury securities	229,563		132		(179)		229,516
U.S. agency securities	39,225		—		(365)		38,860
Total cash equivalents and investments	$	444,589	$	245	$	(756)	$	444,078

Classified as:
Cash equivalents							$	78,536
Short-term investments							365,542
Long-term investments							—
Total cash equivalents, and investments							$	444,078

The fair value and amortized cost of cash equivalents and available-for-sale securities by major security type as of December 31, 2022 are presented in the following table:


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	10,679	$	—	$	—	$	10,679
Commercial paper	4,956		—		(2)		4,954
Corporate bonds	156,019		25		(2,788)		153,256
U.S. treasury securities	323,077		5		(5,060)		318,022
U.S. agency securities	41,078		—		(1,662)		39,416
Total cash equivalents and investments	$	535,809	$	30	$	(9,512)	$	526,327

Classified as:
Cash equivalents							$	11,760
Short-term investments							455,416
Long-term investments							59,151
Total cash equivalents, and investments							$	526,327

The fair values of available-for-sale debt investments by contractual maturity as of December 31, 2023 and 2022 were as follows:


	December 31,
	2023		2022
	(in thousands)
Due in 1 year or less	$	365,542	$	456,497
Due in 1 - 2 years	—		59,151
Due in 3 years	—		—
Instruments not due at a single maturity date	78,536		10,679
Total cash equivalents and investments	$	444,078	$	526,327

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Statement of Stockholders' Equity [Abstract]
Offering costs	$ 1.7

Investments

12 Months Ended

Dec. 31, 2023

Investments, All Other Investments [Abstract]

Investments

The fair value and amortized cost of cash equivalents and available-for-sale securities by major security type as of December 31, 2023 are presented in the following table:


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	78,536	$	—	$	—	$	78,536
Corporate bonds	97,265		113		(212)		97,166
U.S. treasury securities	229,563		132		(179)		229,516
U.S. agency securities	39,225		—		(365)		38,860
Total cash equivalents and investments	$	444,589	$	245	$	(756)	$	444,078

Classified as:
Cash equivalents							$	78,536
Short-term investments							365,542
Long-term investments							—
Total cash equivalents, and investments							$	444,078

The fair value and amortized cost of cash equivalents and available-for-sale securities by major security type as of December 31, 2022 are presented in the following table:


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	10,679	$	—	$	—	$	10,679
Commercial paper	4,956		—		(2)		4,954
Corporate bonds	156,019		25		(2,788)		153,256
U.S. treasury securities	323,077		5		(5,060)		318,022
U.S. agency securities	41,078		—		(1,662)		39,416
Total cash equivalents and investments	$	535,809	$	30	$	(9,512)	$	526,327

Classified as:
Cash equivalents							$	11,760
Short-term investments							455,416
Long-term investments							59,151
Total cash equivalents, and investments							$	526,327

The Company believes that it is more likely than not that investments in an unrealized loss position will be held until maturity and all interest and principal will be received. The Company does not intend to sell these investments and it is more likely than not that the Company will not be required to sell the investment before recovery of its amortized cost basis.

The fair values of available-for-sale debt investments by contractual maturity as of December 31, 2023 and 2022 were as follows:


	December 31,
	2023		2022
	(in thousands)
Due in 1 year or less	$	365,542	$	456,497
Due in 1 - 2 years	—		59,151
Due in 3 years	—		—
Instruments not due at a single maturity date	78,536		10,679
Total cash equivalents and investments	$	444,078	$	526,327

As of December 31, 2023 and 2022, the remaining contractual maturities of available-for-sale securities were one year and less. Realized losses on available-for-sale securities for the year ended December 31, 2023 were $1.0 million. There were no significant realized losses on available-for-sale securities for the years ended December 31, 2022 and 2021. As of December 31, 2023 and 2022, unrealized losses on available-for-sale securities are not attributed to credit risk. The Company believes that it is more likely than not that investments in an unrealized loss position will be held until maturity and all interest and principal will be received. The Company believes that an allowance for credit losses is unnecessary because the unrealized losses on certain of the Company’s available-for-sale securities are due to market factors. As of December 31, 2023 and 2022, securities with a fair value of $48.4 million and $329.4 million, respectively, were in a continuous net unrealized loss position for more than 12 months. To date, the Company has not recorded any impairment charges on available-for-sale securities.

As of December 31, 2023 and 2022, the Company recognized $1.7 million and $1.8 million, respectively, of accrued interest receivable from available-for-sale securities within prepaid expenses and other current assets on the consolidated balance sheets.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Financial Assets Subject to Fair Value Measurements on Recurring Basis and Level of Inputs Used in Such Measurements by Major Security Type


	December 31, 2023
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Financial Assets:
Money market funds ¹	$	78,536	$	—	$	—	$	78,536
Corporate bonds	—		97,166		—		97,166
U.S. treasury securities	229,516		—		—		229,516
U.S. agency securities	—		38,860		—		38,860
Total financial assets	$	308,052	$	136,026	$	—	$	444,078

¹ Included within cash and cash equivalents on the Company’s consolidated balance sheet


	December 31, 2022
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Financial Assets:
Money market funds ¹	$	10,679	$	—	$	—	$	10,679
Commercial paper	—		4,954		—		4,954
Corporate bonds	—		153,256		—		153,256
U.S. treasury securities	318,022		—		—		318,022
U.S. agency securities	—		39,416		—		39,416
Total financial assets	$	328,701	$	197,626	$	—	$	526,327

¹ Included within cash and cash equivalents on the Company’s consolidated balance sheet

Net Loss and Net Loss Per Share - Schedule of Anti-dilutive Shares (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	36,190,861	24,294,136	17,209,986
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	21,812,946	17,569,575	10,239,167
Restricted stock units subject to vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	12,180,471	5,493,406	4,261,108
Expected shares purchased under Employee Stock Purchase Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	2,168,264	1,092,314	474,966
Founder shares subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	0	0	1,514,424
Early exercised stock options subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	29,180	138,841	720,321

401(k) Plan (Details) - USD ($) $ in Millions	12 Months Ended
401(k) Plan (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Contribution expenses	$ 2.5	$ 2.3	$ 1.8

Balance Sheet Components - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Depreciation and amortization expense	$ 14,200	$ 14,300	$ 10,500
Disposal of property, plant, and equipment	$ 100	100	0
Reportable segments \| segment	1
Operating lease right-of-use asset	$ 63,703	83,592		$ 78,643	$ 80,314	$ 81,964	$ 85,245	$ 86,837	$ 57,057
Sublease rental income	22,700
Impairment of long-lived asset	13,245	$ 0	$ 0
South San Francisco Buliding
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	13,800
Operating lease right-of-use asset	$ 27,000
Measurement Input, Discount Rate \| Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.09

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Property and Equipment, Net

Property and Equipment, Net


	December 31,
	2023		2022
	(in thousands)
Leasehold improvements	$	108,621	$	108,550
Laboratory equipment	33,157		32,601
Computer equipment and purchased software	4,663		4,533
Furniture and fixtures	4,121		4,012
Construction in progress	—		28
Total	150,562		149,724
Less: accumulated depreciation	(51,084)		(36,885)
Total property and equipment, net	$	99,478	$	112,839

Schedule of Accrued Liabilities

Accrued Liabilities

Accrued liabilities consist of the following:


	December 31,
	2023		2022
	(in thousands)
Accrued compensation and related benefits	$	12,665	$	17,935
Accrued research and development expenses	9,315		11,790
Accrued lease liability	6,775		6,002
Unvested shares liability	532		1,898
Other	1,809		2,118
Total accrued and other current liabilities	$	31,096	$	39,743

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2023
Retirement Benefits [Abstract]
401(k) Plan	401(k) PlanIn April 2018, the Company began to sponsor a 401(k) retirement savings plan for the benefit of its employees. All employees are eligible to participate, provided they meet the requirements of the plan. The Company made contributions to the plan for eligible participants, and recorded contribution expenses of $2.5 million, $2.3 million and $1.8 million for the years ended December 31, 2023, 2022 and 2021, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//715/tableOfContent

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation and related benefits	$ 12,665				$ 17,935
Accrued research and development expenses	9,315				11,790
Accrued lease liability	6,775				6,002
Unvested shares liability	532				1,898
Other	1,809				2,118
Total accrued and other current liabilities	$ 31,096	$ 31,195	$ 44,263	$ 44,624	$ 39,743	$ 36,938	$ 34,360	$ 27,763

License and Collaboration Agreements - Other License and Collaboration Agreements (Details) - USD ($)					1 Months Ended			3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
	Jan. 05, 2022	Dec. 14, 2020	Oct. 06, 2020	Nov. 01, 2019	Jul. 31, 2023	Oct. 31, 2021	Feb. 28, 2021	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development								$ 45,977,000	$ 62,038,000	$ 80,238,000	$ 63,641,000	$ 57,171,000	$ 60,156,000	$ 142,276,000	$ 117,327,000	$ 188,253,000	$ 180,968,000	$ 242,914,000	$ 256,387,000	$ 220,176,000
Equity method investments								6,450,000	11,946,000	14,381,000	20,951,000	23,673,000	27,663,000	11,946,000	23,673,000	6,450,000	20,951,000	3,645,000	17,317,000
Payments for additional investment in interest																		0	0	17,710,000
Impairment loss on equity method investment																		7,000,000	0	0
Revenue recognized								$ 22,000	$ 22,000	$ 30,000	$ 27,000	$ 64,000	$ 39,000	$ 52,000	$ 103,000	$ 74,000	$ 130,000	95,000	156,000	114,089,000
Payment for investment in stock																		438,629,000	248,109,000	525,583,000
University Of Texas M D Anderson Cancer Center
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration agreement, upfront payment																		3,000,000			$ 3,000,000
Collaboration agreement, term (in years)			5 years
Committed funding			$ 15,000,000
Allogene Overland, Allogene Overland BioPharm (HK) Limited
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognized																		100,000	200,000	114,100,000
Net cost recoveries																		0	700,000	0
Antion
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development					$ 1,000,000
Warrants and rights outstanding					3,000,000
Investment in equity securities					1,000,000
Research and development \| University Of Texas M D Anderson Cancer Center
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration costs																		900,000	1,400,000	1,000,000
Notch Therapeutics, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investments				$ 5,000,000														3,600,000	12,800,000
Ownership percentage				25.00%
Payments for additional investment in interest						$ 1,800,000	$ 15,900,000
Impairment loss on equity method investment																		3,000,000	0	0
Notch Therapeutics, Inc. \| Voting Interest
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage						23.00%	20.70%
Allogene Overland
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage		49.00%
Equity method investments																		0	4,500,000
Allogene Overland \| Overland Pharmaceuticals Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage		51.00%
Joint Venture \| Allogene Overland \| Overland Pharmaceuticals Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront and quarterly cash payments		$ 117,000,000
Joint venture capital support payments		$ 40,000,000
Probability percentage		65.00%
Annual discount rate		11.90%
Joint Venture \| Allogene Overland \| Allogene Overland, Allogene Overland BioPharm (HK) Limited
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration agreement, upfront payment		$ 40,000,000
Aggregate potential milestone payments per target		40,000,000
Fair value		79,000,000
Initial transaction price		119,000,000
Joint steering committee participation		600,000
Equity method investments		0																			$ 11,500,000
Joint Venture \| Allogene Overland \| Allogene Overland, Allogene Overland BioPharm (HK) Limited \| Intellectual Property
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Initial transaction price		114,000,000
Joint Venture \| Allogene Overland \| Allogene Overland, Allogene Overland BioPharm (HK) Limited \| Manufacturing License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Initial transaction price		2,300,000
Joint Venture \| Allogene Overland \| Allogene Overland, Allogene Overland BioPharm (HK) Limited \| Future Intellectual Property
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Initial transaction price		$ 2,100,000
Antion Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration agreement, upfront payment	$ 3,500,000
Collaboration costs																		1,800,000	5,000,000
Impairment loss on equity method investment																		4,000,000	0
Prior investment obligation					3,000,000
Costs incurred related to milestone achievement																		400,000	0
Antion Collaboration Agreement \| Current Accrued and Other Liabilities
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration costs																		0	500,000
Antion Collaboration Agreement \| Other Noncurrent Assets
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity investment, total																		0	3,000,000
Antion Collaboration Agreement \| Preferred Stock
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment for investment in stock	3,000,000
Preferred stock investment payable					$ 2,000,000
Antion Collaboration Agreement, Milestone Achievement One
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable	35,300,000
Antion Collaboration Agreement, Milestone Achievement Two
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable	$ 2,000,000
Notch Therapeutics, Inc. \| Research and development
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration costs																		1,800,000	3,800,000	4,300,000
Notch Therapeutics, Inc. \| License and Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration agreement, upfront payment				$ 10,000,000
Research and development																						$ 10,000,000
Notch Therapeutics, Inc. \| License and Collaboration Agreement \| Maximum \| Pre-Clinical Development Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target																		4,000,000
Notch Therapeutics, Inc. \| License and Collaboration Agreement \| Maximum \| Clinical, Regulatory, and Commercial Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target																		283,000,000
Notch Therapeutics, Inc. \| Research Collaboration And License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable																		7,300,000
Notch Therapeutics, Inc. \| Research Collaboration And License Agreement \| Pre-Clinical Development Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development																		$ 0	$ 0	$ 300,000

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Schedule of Lease Liabilities

The balance sheet classification of our lease liabilities were as follows (in thousands):


	December 31, 2023		December 31, 2022
Operating lease liabilities
Current portion included in accrued and other current liabilities	$	6,775	$	6,002
Long-term portion of lease liabilities	88,346		95,122
Total operating lease liabilities	$	95,121	$	101,124

Schedule of Lease Costs

The components of lease costs for operating leases, which were recognized in operating expenses, were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Operating lease cost	$	12,711	$	11,664	$	7,513
Variable lease cost	3,102		2,139		1,629
Total lease costs	$	15,813	$	13,803	$	9,142

Lessee, Operating Lease, Liability, Maturity

The undiscounted future non-cancellable lease payments under the Company's operating leases as of December 31, 2023 is as follows:


Year ending December 31:	(in thousands)
2024	$	12,447
2025	12,627
2026	12,819
2027	13,257
2028 and thereafter	77,234
Total undiscounted lease payments	128,384
Less: Present value adjustment	(33,263)
Total	$	95,121

Fair Value Measurements - Additional Information (Detail) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities	$ 0	$ 0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	444,078,000	526,327,000
Level 3 \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 0	$ 0

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity Under Plan

The following summarizes option activity under the 2018 Plan:


	Outstanding Options
	Number of Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Term	Aggregate Intrinsic Value
				(in years)	(in thousands)
Balance, December 31, 2022	17,569,575	$	12.90	7.73	$	6,658
Options granted	10,315,270	4.94
Options exercised	(850,396)	2.45			$	2,334
Options forfeited	(5,221,503)	11.31
Balance, December 31, 2023	21,812,946	$	9.93	7.53	$	662
Exercisable, December 31, 2023	18,687,724	$	9.98	7.56	$	639
Vested and expected to vest, December 31, 2023	21,812,946	$	9.93	7.53	$	662

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The fair value of employee, consultant and director stock option awards was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions:


	Year Ended December 31,
	2023	2022
Fair value of common stock	$2.72 - $7.23	$7.08 - $17.28
Expected term in years	5.27 - 6.08	5.25 - 6.08
Expected volatility	73.18% - 74.10%	70.82% - 73.39%
Expected risk-free interest rate	3.45% - 4.61%	1.61% - 4.12%
Expected dividend	0%	0%

Schedule of Restricted Stock Units Activity

The following summarizes restricted stock unit activity under the 2018 Plan:


	Outstanding Restricted Stock Units
	Restricted Stock Units	Weighted- Average Grant Date Fair Value per Share		Weighted Average Remaining Vesting Life	Aggregate Intrinsic Value
				(in years)	(in thousands)
Unvested December 31, 2022	5,493,406	$	16.86	1.54	$	34,554
Granted	12,119,645	4.55		1.79
Vested	(1,905,294)	17.47
Forfeited	(3,527,286)	9.39
Unvested December 31, 2023	12,180,471	$	6.68	2.00	$	39,099
Vested and expected to vest, December 31, 2023	12,180,471	$	6.68	2.00	$	39,099

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The fair values of the rights granted under the ESPP were calculated using the following assumptions:


	Year ended December 31,
	2023	2022
Expected term (in years)	0.50 – 2.00	0.50 – 2.00
Volatility	67.32% - 85.05%	74.20% - 85.63%
Risk-free interest rate	4.05%-5.35%	0.86% - 3.88%
Dividend yield	—	—

License and Collaboration Agreements - Pfizer, Cellectis, and Servier Collaboration Agreements (Details) € in Millions	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 EUR (€)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development	$ 45,977,000	$ 62,038,000	$ 80,238,000	$ 63,641,000	$ 57,171,000	$ 60,156,000	$ 142,276,000	$ 117,327,000	$ 188,253,000	$ 180,968,000	$ 242,914,000	$ 256,387,000	$ 220,176,000
Pfizer
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty obligation period from date of first sale											12 years
Cellectis \| Research Collaboration And License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Maximum payments required per product against selected target											$ 185,000,000
Servier \| License and Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development costs payable by the Company (in percent)											60.00%
Development cost payable by collaboration partner (in percent)											40.00%
Net cost recoveries											$ 0	19,900,000	17,100,000
Related Party \| License and Collaboration Agreement \| Servier
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Other receivables											0	1,500,000
Asset Contribution Agreement \| Pfizer
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target											325,000,000
Milestone payments											0	0	0
Pre-Clinical Development Milestone \| Cellectis \| Research Collaboration And License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development											0	0	10,000,000
Pre-Clinical Development Milestone \| Servier \| Research Collaboration And License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development											0	$ 8,000,000	$ 0
Regulatory Milestone \| Servier \| License and Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable											42,000,000
Sales Milestone \| Servier \| License and Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable											77,800,000			€ 70.5
Minimum \| Asset Contribution Agreement \| Pfizer
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target											30,000,000
Maximum \| Cellectis \| Research Collaboration And License Agreement \| Development And Sales
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target											2,800,000,000
Maximum \| Asset Contribution Agreement \| Pfizer
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target											60,000,000
Aggregate potential regulatory and development milestones											840,000,000
Maximum \| Regulatory Milestone \| Servier \| License and Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target											137,500,000
Maximum \| Sales Milestone \| Servier \| License and Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target											$ 78,000,000

Description of Business and Summary of Significant Accounting Policies - Reconciliation of Restated Financial Statements - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Consolidated Statements of Cash Flow
Net loss	$ (99,968)	$ (78,607)	$ (179,200)	$ (158,897)	$ (241,487)	$ (243,139)	$ (327,265)	$ (340,414)	$ (182,051)
Non-cash collaboration revenue - related party	(20)	(26)	(34)	(69)	(49)	(87)	(63)	(104)	(75,740)
Share of loss from equity method investments	2,935	2,535	5,370	6,525	10,866	9,247	10,672	12,883	4,090
Changes in operating assets and liabilities:
Deferred revenue	(3)	(3)	(3)	(17)	(3)	(19)	(3)	(21)	(38,297)
Other long-term liabilities	(626)	(601)	(621)	(1,028)	(615)	(1,454)	(611)	(1,882)	910
Net cash used in operating activities	(66,639)	(68,237)	(128,496)	(110,768)	(184,026)	(158,423)	$ (237,733)	(220,519)	(184,812)
As Previously Reported
Condensed Consolidated Statements of Cash Flow
Net loss	(98,704)	(79,850)	(176,693)	(154,637)	(238,008)	(237,785)		(332,632)	(257,005)
Non-cash collaboration revenue - related party	0	0	0	0	0	0		0	0
Share of loss from equity method investments	1,693	3,800	2,907	2,309	7,452	3,959		5,188	3,444
Changes in operating assets and liabilities:
Deferred revenue	(612)	(17)	(656)	413	(649)	466		462	(38,569)
Other long-term liabilities	(59)	(635)	(46)	(1,571)	(83)	(2,092)		(2,556)	1,042
Net cash used in operating activities	(66,639)	(68,237)	(128,496)	(110,768)	(184,026)	(158,423)		(220,519)	(184,812)
Restatement Adjustment
Condensed Consolidated Statements of Cash Flow
Net loss	(1,264)	1,243	(2,507)	(4,260)	(3,479)	(5,354)		(7,782)	74,954
Non-cash collaboration revenue - related party	(20)	(26)	(34)	(69)	(49)	(87)		(104)	(75,740)
Share of loss from equity method investments	1,242	(1,265)	2,463	4,216	3,414	5,288		7,695	646
Changes in operating assets and liabilities:
Deferred revenue	609	14	653	(430)	646	(485)		(483)	272
Other long-term liabilities	(567)	34	(575)	543	(532)	638		674	(132)
Net cash used in operating activities	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0		$ 0	$ 0

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 211,124	$ 174,222	$ 144,133
Tax credit carryforwards	32,826	24,517	15,595
Intangibles	14,524	16,966	14,092
Accrued expenses	3,039	4,227	3,091
Lease liabilities	26,358	28,298	15,724
Stock based compensation	25,350	25,731	14,693
Investments	28,735	26,291	15,849
Capitalized R&D	73,492	41,273	0
Other	2,189	1,741	1,076
Total deferred tax assets	417,637	343,266	224,253
Deferred tax liabilities:
Fixed assets	0	0	(250)
Right of use leased assets	(17,652)	(23,392)	(12,478)
Other	(301)	(244)	(68)
Total deferred tax liabilities	(17,953)	(23,636)	(12,796)
Net deferred tax assets	399,684	319,630	211,457
Valuation allowance	(399,684)	(319,630)	(211,457)
Net deferred tax assets	$ 0	$ 0	$ 0