Allogene Therapeutics (ALLO) 10-Q 13 May 24 2024 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2024	May 09, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
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, $0.001 par value per share
Trading Symbol	ALLO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		170,853,379
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Central Index Key	0001737287
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 51,039	$ 83,155
Short-term investments	333,821	365,542
Prepaid expenses and other current assets	10,504	10,418
Total current assets	395,364	459,115
Long-term investments	12,405	0
Operating lease right-of-use asset	64,483	63,703
Property and equipment, net	95,931	99,478
Restricted cash	10,292	10,292
Other long-term assets	5,159	6,604
Equity method investments	2,716	3,645
Total assets	586,350	642,837
Current liabilities:
Accounts payable	5,779	5,897
Accrued and other current liabilities	25,029	31,096
Deferred revenue	86	86
Total current liabilities	30,894	37,079
Lease liability, noncurrent	88,916	88,346
Other long-term liabilities	5,173	5,179
Total liabilities	124,983	130,604
Commitments and Contingencies (Notes 6 and 7)
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 shares authorized as of March 31, 2024 and December 31, 2023; no shares were issued and outstanding as of March 31, 2024 and December 31, 2023	0	0
Common stock, $0.001 par value: 400,000,000 shares authorized as of March 31, 2024 and December 31, 2023; 170,452,967 and 168,642,238 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively	170	169
Additional paid-in capital	2,089,357	2,075,252
Accumulated deficit	(1,627,233)	(1,562,233)
Accumulated other comprehensive loss	(927)	(955)
Total stockholders’ equity	461,367	512,233
Total liabilities and stockholders’ equity	$ 586,350	$ 642,837

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	170,452,967	168,642,238
Common stock, shares outstanding (in shares)	170,452,967	168,642,238

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenues
Collaboration revenue - related party	$ 22	$ 30
Operating expenses:
Research and development	52,259	80,238
General and administrative	17,267	18,884
Total operating expenses	69,526	99,122
Loss from operations	(69,504)	(99,092)
Other income (expense), net:
Interest and other income, net	5,433	2,059
Other expenses	(929)	(2,935)
Total other income (expense), net	4,504	(876)
Net loss	(65,000)	(99,968)
Other comprehensive loss:
Net unrealized gain on available-for-sale investments	28	3,992
Net comprehensive loss	$ (64,972)	$ (95,976)
Net loss per share, basic (in dollars per share)	$ (0.38)	$ (0.69)
Net loss per share, diluted (in dollars per share)	$ (0.38)	$ (0.69)
Weighted-average number of shares used in computing net loss per share, basic (in shares)	169,128,362	144,563,829
Weighted-average number of shares used in computing net loss per share, diluted (in shares)	169,128,362	144,563,829

Condensed Consolidated Statem_2

Condensed 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, 2022		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 upon exercise of stock options and vesting of RSUs (in shares)		942,276
Issuance of common stock upon exercise of stock options and vesting of RSUs	0	$ 1	(1)
Vesting of early exercised common stock	603		603
Stock-based compensation	18,770		18,770
Employee stock purchase plan (in shares)		359,753
Employee stock purchase plan	1,731	$ 1	1,730
Net loss	(99,968)			(99,968)
Net unrealized gain on available-for-sale investments	3,992				3,992
Ending balance (in shares) at Mar. 31, 2023		145,740,333
Ending balance at Mar. 31, 2023	$ 592,010	$ 146	1,932,734	(1,334,936)	(5,934)
Beginning balance (in shares) at Dec. 31, 2023	168,642,238	168,642,238
Beginning balance at Dec. 31, 2023	$ 512,233	$ 169	2,075,252	(1,562,233)	(955)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and vesting of RSUs (in shares)		1,551,729
Issuance of common stock upon exercise of stock options and vesting of RSUs	794	$ 1	793
Vesting of early exercised common stock	532		532
Stock-based compensation	11,924		11,924
Employee stock purchase plan (in shares)		259,000
Employee stock purchase plan	856	$ 0	856
Net loss	(65,000)			(65,000)
Net unrealized gain on available-for-sale investments	$ 28				28
Ending balance (in shares) at Mar. 31, 2024	170,452,967	170,452,967
Ending balance at Mar. 31, 2024	$ 461,367	$ 170	$ 2,089,357	$ (1,627,233)	$ (927)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (65,000)	$ (99,968)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	11,924	18,770
Depreciation and amortization	3,555	3,507
Net amortization/accretion on investment securities	(2,797)	508
Non-cash rent expense	(55)	207
Non-cash collaboration revenue - related party	(14)	(20)
Share of loss from equity method investments	929	2,935
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(86)	1,263
Other long-term assets	1,445	45
Accounts payable	(118)	1,057
Accrued and other current liabilities	(5,690)	5,686
Deferred revenue	0	(3)
Other long-term liabilities	8	(626)
Net cash used in operating activities	(55,899)	(66,639)
Cash flows from investing activities:
Purchases of property and equipment	(8)	(1,035)
Proceeds from sales of investments	0	5,623
Proceeds from maturities of investments	103,272	143,441
Purchase of investments	(81,131)	(35,094)
Net cash provided by investing activities	22,133	112,935
Cash flows from financing activities:
Proceeds from issuance of common stock upon exercise of stock options	794	0
Proceeds from issuance of common stock under the employee stock purchase plan	856	1,731
Net cash provided by financing activities	1,650	1,731
Net change in cash and cash equivalents and restricted cash	(32,116)	48,027
Cash and cash equivalents and restricted cash — beginning of period	93,447	72,196
Cash and cash equivalents and restricted cash — end of period	61,331	120,223
Non-cash operating activities:
Right-of-use asset obtained in exchange for lease liability	2,409	0
Non-cash deferred revenue and other long-term liabilities	3,079	3,137
Supplemental disclosure:
Cash paid for amounts included in the measurement of lease liabilities	$ (3,068)	$ (2,965)

Description of Business

Description of Business	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business 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 and autoimmune diseases. The Company is developing a pipeline of “off-the-shelf” T cell product candidates that are designed to target and kill cancer cells in patients or eliminate pathogenic autoreactive cells in patients with autoimmune disorders. The Company’s engineered T cells are allogeneic, meaning they are derived from healthy donors for intended use in any patient, rather than from an individual patient for that patient’s use, as in the case of autologous T cells. The Company believes this key difference will enable it to deliver readily available treatments faster, more reliably, at greater scale, and to more patients. 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 and cash equivalents and investments of $397.3 million as of March 31, 2024. Since inception through March 31, 2024, the Company has incurred cumulative net losses of $1,627.2 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the SEC. Accordingly, they do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the Company’s opinion, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation of the results of operations and cash flows for the periods presented have been included. The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Allogene Therapeutics, B.V. The subsidiary was dissolved on January 3, 2024. The condensed consolidated balance sheet as of March 31, 2024, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023, the condensed consolidated statements of stockholders’ equity as of March 31, 2024 and 2023, the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023, and the financial data and other financial information disclosed in the notes to the condensed consolidated financial statements are unaudited. The results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the year ending December 31, 2024, or for any other future annual or interim period. These condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and related notes for the year ended December 31, 2023, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 14, 2024. Use of Estimates The preparation of condensed 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 condensed consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying condensed 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. Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2024, as compared to the significant accounting policies described in Note 1 of the “Notes to Financial Statements” in the Company’s audited financial statements included in its Annual Report. 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 condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted The Company continues to monitor new accounting pronouncements issued by the FASB and does not believe any accounting pronouncements issued through the date of this report will have a material impact on the Company's condensed consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements 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 as of March 31, 2024 and as of December 31, 2023. 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 March 31, 2024 and as of December 31, 2023 are presented in the following tables: March 31, 2024 Level 1 Level 2 Level 3 Fair Value (In thousands) Financial Assets: Money market funds (1) $ 45,019 $ — $ — $ 45,019 Commercial paper — 4,879 — 4,879 Corporate bonds — 109,071 — 109,071 U.S. treasury securities 203,676 — — 203,676 U.S. agency securities — 28,600 — 28,600 Total financial assets $ 248,695 $ 142,550 $ — $ 391,245 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)

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2024
Investments, All Other Investments [Abstract]
Financial Instruments	Financial Instruments The fair value and amortized cost of cash equivalents and available-for-sale securities by major security type as of March 31, 2024 and as of December 31, 2023 are presented in the following tables: March 31, 2024 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) Money market funds $ 45,019 $ — $ — $ 45,019 Commercial paper 4,886 — (7) 4,879 Corporate bonds 109,188 31 (148) 109,071 U.S. treasury securities 203,894 2 (220) 203,676 U.S. agency securities 28,741 2 (143) 28,600 Total cash equivalents and investments $ 391,728 $ 35 $ (518) $ 391,245 Classified as: Cash equivalents $ 45,019 Short-term investments 333,821 Long-term investments 12,405 Total cash equivalents and investments $ 391,245 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 As of March 31, 2024, the remaining contractual maturities of available-for-sale securities were less than 2 years. Realized losses on available-for-sale securities for the three months ended March 31, 2024 and 2023 were zero and $1.0 million, respectively. As of March 31, 2024, 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 March 31, 2024 and December 31, 2023, securities with a fair value of $29.4 million and $48.4 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 March 31, 2024 and December 31, 2023, the Company recognized $1.7 million of accrued interest receivable from available-for-sale securities within prepaid expenses and other current assets on the condensed consolidated balance sheets.

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Property and Equipment, Net Property and Equipment consist of the following: March 31, December 31, (In thousands) Leasehold improvements 108,621 108,621 Laboratory equipment 33,162 33,157 Computer equipment and purchased software 4,663 4,663 Furniture and fixtures 4,124 4,121 Total 150,570 150,562 Less: accumulated depreciation (54,639) (51,084) Total property and equipment, net $ 95,931 $ 99,478 Accrued and Other Current Liabilities 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. During the three months ended March 31, 2024, the Company paid approximately $2.6 million for severance and other employee benefits. As of March 31, 2024, $0.4 million of the severance and other employee benefits accrual was included in accrued and other current liabilities on the condensed consolidated balance sheet.

License and Collaboration Agree

License and Collaboration Agreements	3 Months Ended
	Mar. 31, 2024
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 because the Company does not presently hold commercial rights in 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 three months ended March 31, 2024 or 2023. 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’s 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 third party 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’s 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 condensed consolidated statements of operations. For the three months ended March 31, 2024 and 2023, no clinical development milestones were achieved. Exclusive License Agreement with Servier As part of the Pfizer Agreement, Pfizer assigned to the Company an Exclusive License 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 ($76.1 million), respectively. The foregoing milestones are subject to certain adjustments if the Company obtains rights for certain products outside of the United States. 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. The Company subsequently submitted to a review of the Company's manufacturing costs of CD19 Products and 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. In May 2024, the Company entered into an Amendment and Settlement Agreement with Servier (the Servier Amendment). Under the Servier Amendment, among other things, Servier waived any right to receive a refund for past costs under the cost-sharing, and the parties provided mutual releases for all current disputes and any and all claims either party has or has ever had relating to such disputes. See Note 13. Subsequent Events for a description of the Servier Amendment. For the three months ended March 31, 2024 and 2023, the Company recorded zero and $0.2 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 March 31, 2024 and December 31, 2023, no amounts due from Servier were recorded in the condensed consolidated balance sheets. 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. 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 March 31, 2024, 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 $7.25 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. 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. 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 of $30.0 million, 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 investment in Notch, the Amended Notch Agreement grants the Company certain anti-dilution protections up to certain limits for certain pre-IPO equity financings. As of March 31, 2024, no Released Targets were out-licensed by Notch. For the three months ended March 31, 2024 and 2023, the Company recorded zero and $1.0 million, respectively, in collaboration costs as research and development expenses. No milestones were achieved by Notch for the three months ended March 31, 2024 and 2023. 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 three months ended March 31, 2024 and 2023, the Company recorded less than $0.1 million and $0.4 million, respectively, in collaboration costs as research and development expenses. Joint Venture and License Agreement with Allogene Overland Biopharm (CY) Limited On December 14, 2020, the Company entered into a 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, 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 (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 March 31, 2024, 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 delivery of 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 March 31, 2024 and December 31, 2023. The Company does not have the power to direct the activities which most significantly affect Allogene Overland's economic performance. Accordingly, 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 March 31, 2024 and December 31, 2023 was zero (see Note 8). For the three months ended March 31, 2024 and 2023, the Company recognized less than $0.1 million of collaboration revenue. For the three months ended March 31, 2024 and 2023, 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. 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 three months ended March 31, 2024, the Company recorded zero research and development expenses related to collaboration costs. For the three months ended March 31, 2023, the Company recorded $0.5 million in research and development expenses related to collaboration costs. As of March 31, 2024 and December 31, 2023, no research and development expenses were recorded in accrued and other liabilities. As of March 31, 2024 and December 31, 2023, the C

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases In August 2018, the Company entered into an operating lease agreement (HQ Lease) for 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 seven 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 through December 31, 2020. 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 eight 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 seven 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 eight 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. In February 2023, the Company entered into a sublease with Bellco Capital Advisors Inc. (Bellco) for 2,218 square feet of office space in Los Angeles, California. The sublease term is 115 months, subject to certain early termination rights. The sublease commenced on January 1, 2024. The Company maintains letters of credit for the benefit of landlords which is disclosed as restricted cash in the condensed consolidated balance sheets. Restricted cash related to letters of credit due to landlords was $6.0 million as of March 31, 2024 and December 31, 2023. The balance sheet classification of our lease liabilities were as follows (in thousands): March 31, 2024 December 31, 2023 Operating lease liabilities Current portion included in accrued and other current liabilities $ 6,930 $ 6,775 Long-term portion of lease liabilities 88,916 88,346 Total operating lease liabilities $ 95,846 $ 95,121 The components of lease costs for operating leases, which were recognized in operating expenses, were as follows (in thousands): Three Months Ended 2024 2023 Operating lease cost $ 3,020 $ 3,181 Variable lease cost 867 691 Total lease costs $ 3,887 $ 3,872 Cash paid for amounts included in the measurement of lease liabilities for the three months ended March 31, 2024 was $3.1 million and was included in net cash used in operating activities in the Company's condensed consolidated statements of cash flows. The undiscounted future non-cancellable lease payments under the Company's operating leases as of March 31, 2024 were as follows: Year ending December 31: (In thousands) 2024 (remaining 9 months) $ 9,436 2025 12,920 2026 13,163 2027 13,612 2028 14,076 2029 and thereafter 65,385 Total undiscounted lease payments 128,592 Less: Present value adjustment (32,746) Total $ 95,846 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 6.24%. As of March 31, 2024, the weighted average remaining lease term for our operating leases is 8.82 years. Other Commitments 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 condensed consolidated balance sheets as of March 31, 2024 and December 31, 2023. 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 March 31, 2024. The Company enters into contracts in the normal course of business that includes arrangements with clinical research organizations, vendors for preclinical research and vendors for manufacturing. These agreements generally allow for cancellation with notice. As of March 31, 2024, the Company had non-cancellable purchase commitments of $0.9 million.

Equity Method Investments

Equity Method Investments	3 Months Ended
	Mar. 31, 2024
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments 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 March 31, 2024 and December 31, 2023 was $2.7 million and $3.6 million, respectively, and the Company accounted for the investment using the equity method of accounting. For the three months ended March 31, 2024 and 2023, the Company recognized its share of Notch's net loss of $0.9 million and $1.7 million, respectively, under the other expenses caption within the condensed consolidated statements of operations. 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 Shares representing a 49% ownership interest in exchange for entering into a License Agreement. The Company’s total equity investment in Allogene Overland as of March 31, 2024 and December 31, 2023 was zero and the Company accounted for the investment using equity method of accounting. For the three months ended March 31, 2024 and 2023, the Company recognized its share of Allogene Overland's net loss of zero and $1.2 million, respectively, under the other expenses caption within the condensed consolidated statement of operations.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation 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 March 31, 2024, there were 9,738,364 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- Aggregate Intrinsic Value (in years) (in thousands) Balance, December 31, 2023 21,812,946 $ 9.93 7.53 $ 662 Options granted 4,259,396 3.22 9.50 Options exercised (350,118) 2.27 $ 584 Options forfeited (1,696,808) 10.68 Balance, March 31, 2024 24,025,416 $ 8.80 7.80 $ 7,516 Exercisable, March 31, 2024 17,689,533 $ 9.97 7.43 $ 2,262 Vested and expected to vest, March 31, 2024 24,025,416 $ 8.80 7.80 $ 7,516 The aggregate intrinsic values of options 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 March 31, 2024. For the three months ended March 31, 2024, the estimated weighted-average grant-date fair value of employee options granted was $2.15 per share. As of March 31, 2024, there was $54.0 million of unrecognized stock-based compensation related to unvested stock options, which is expected to be recognized over a weighted-average period of 2.4 years. 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: Three Months Ended March 31, 2024 2023 Expected term in years 5.85 - 6.06 6.03 - 6.07 Expected volatility 73.50% 73.85% Expected risk-free interest rate 3.94% - 4.22% 3.45% - 4.10% Expected dividend 0% 0% 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. Restricted Stock Unit Activity The following summarizes restricted stock unit activity under the 2018 Plan: Outstanding Restricted Stock Units Restricted Stock Units Weighted- Weighted Average Remaining Vesting Life Aggregate Intrinsic Value (in years) (in thousands) Unvested December 31, 2023 12,180,471 $ 6.68 2.00 $ 39,099 Granted 4,046,261 4.44 1.85 Vested (1,170,889) 9.82 Forfeited (1,446,452) 8.78 Unvested March 31, 2024 13,609,391 $ 5.52 1.98 $ 60,834 Vested and expected to vest, March 31, 2024 13,609,391 $ 5.52 1.98 $ 60,834 As of March 31, 2024, there was $52.4 million of unrecognized stock-based compensation related to unvested restricted stock units, which is expected to be recognized over a weighted-average period of 2.4 years. 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 March 31, 2024, 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 quarters ended March 31, 2024 and March 31, 2023. The Company recognized $0.7 million and $0.1 million in stock-based compensation expense related to the restricted stock units with a market condition in the quarters ended March 31, 2024 and 2023, respectively. Stock-based compensation expense For the quarters ended March 31, 2024 and 2023, the Company recorded $11.9 million and $18.8 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 condensed consolidated statements of operations and comprehensive loss.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2024
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Collaboration Revenue and Equity Method Investment 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 three months ended March 31, 2024 and 2023, the Company recognized less than $0.1 million of collaboration revenue under this arrangement. For the three months ended March 31, 2024 and 2023, the Company recorded zero and $1.2 million, respectively, of its share of Allogene Overland's net loss as other expenses (see Note 8). Sublease Agreement In December 2018, the Company entered into a sublease with Bellco Capital LLC for 1,293 square feet of office space in Los Angeles, California for a three year term. On April 1, 2020, Bellco 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 chairman, Arie Belldegrun, M.D., FACS, is a trustee of the Belldegrun Family Trust, which controls Bellco. In 2023, the Company exercised its early termination right under the sublease agreement and the sublease was terminated effective December 31, 2023. In February 2023, the Company entered into a new sublease agreement with Bellco for 2,218 square feet of office space in Los Angeles, California. The sublease term is 115 months, subject to certain early termination rights. The sublease commenced on January 1, 2024. The total right of use asset and associated lease liability recorded related to this related party lease was $2.4 million as of March 31, 2024. For the three months ended March 31, 2024, the Company recorded $0.1 million of rent expense related to this lease. 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. In December 2023, the service agreement between the Company and Two River was terminated. The costs incurred for services provided under this agreement were $0.1 million for the three months ended March 31, 2023. In August 2018, the Company entered into a consulting agreement with Bellco Capital LLC. Pursuant to the consulting agreement, Bellco Capital LLC provides certain services for the Company, which are performed by Dr. Belldegrun, the Company's executive chair, and inc lude 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 Capital LLC $40,217 per month in arrears commencing January 2022. The Company may also, at its discretion, pay Bellco Capital LLC an annual performance award in an amount up to 60% of the aggregate compensation payable to Bellco Capital LLC in a calendar year. The Company also reimburses Bellco Capital LLC 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 $0.2 million for the three months ended March 31, 2024 and 2023.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company has a history of losses and expects to record a loss in 2024. The Company continues to maintain a full valuation allowance against its net deferred tax assets.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share for the period presented due to their anti-dilutive effect: March 31, 2024 2023 Stock options to purchase common stock 24,025,416 23,548,486 Restricted stock units subject to vesting 13,609,391 13,587,470 Expected shares to be purchased under Employee Stock Purchase Plan 1,077,525 1,234,606 Early exercised stock options subject to future vesting — 105,743 Total 38,712,332 38,476,305

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Servier Amendment and Settlement Agreement On May 10, 2024, the Company and Servier entered into the Servier Amendment which settles all existing disputes (as described in Note 6) between the Company and Servier relating to each party’s performance under the Servier Agreement. The Servier Amendment also restructures the parties’ relationship on the following terms: (1) The Company’s licensed territory was expanded to include the European Union and the United Kingdom. The Company was also granted an option to further extend its licensed territory to include China and Japan upon the objective showing of sufficient resources to develop licensed products in those countries, which could be met through the Company entering into a strategic partnership covering those countries. Additionally, the Company agreed to waive certain of its rights under the Servier Agreement to elect a conversion of its license to the CD19 Products to a worldwide license. (2) Under the Servier Agreement, Servier sublicenses to the Company certain rights which Servier licenses from Cellectis pursuant to a first development and commercialization agreement, dated February 7, 2014, by and between Cellectis and Servier (as amended, the Servier-Cellectis Agreement). All of the Company’s future milestone payments (regulatory and sales) under the Servier Agreement are modified to be the same as, and to coincide with, Servier’s milestone payments to Cellectis that are required under the Servier-Cellectis Agreement. As amended by the Servier Amendment, the Servier Agreement provides for aggregate potential payments by the Company to Servier of up to €75.0 million, of which €60.0 million remains, upon successful completion of various regulatory milestones in the United States, European Union and the United Kingdom for the initial indication of each licensed product, with additional payments of €55.0 million due for each subsequent indication, and aggregate potential payments by the Company to Servier of up to €80.0 million upon achievement of certain net sales milestones for each licensed product. Should Servier’s rights and obligations under the Servier-Cellectis Agreement be assigned to the Company, these milestone payments would terminate, and the Company would assume Servier’s milestone payment obligation to Cellectis. In the absence of any such assignment, Servier will remain responsible for making milestone payments that may be due to Cellectis under the Servier-Cellectis Agreement. (3) The Company agreed to transfer €20.0 million into an escrow account in connection with a potential future milestone payment, which is included in the remaining €60.0 million in milestone payments referenced above. Such milestone payment will be triggered, if at all, upon the occurrence of one of these events: (1) the Company doses the first subject in its first phase 3 clinical study for a CD19 CAR-T product that is a licensed product under the Servier Agreement, (2) the Company submits a phase 2 clinical study for a licensed product to the U.S. Food and Drug Administration or the European Medicines Agency, and such phase 2 clinical study is accepted for regulatory approval as a pivotal study, or (3) a final and definitive decision of a tribunal or court finding that under the Servier-Cellectis Agreement the milestone has occurred and the €20.0 million payment is due to Cellectis. (4) The Company agreed to pay to Servier royalties on annual net sales of any licensed products that are commercialized by the Company that is directed at CD19. Such royalties include tiered royalties on annual net sales in the United States and a flat royalty on annual net sales in territories outside the United States. The United States royalty rates are in a range from the low tens to the mid teen percentages, and the ex-U.S. royalty rate is 10%. Such royalties may be reduced for interchangeable drug entry, expiration of patent rights and amounts paid pursuant to licenses of third-party patents. This royalty obligation begins upon the first commercial sale of such product in a given country and ends after the later of a defined number of years or the expiration of the last to expire licensed patent covering the product in such country. The net effect of the Servier Amendment is that the Company’s royalty rate in the United States for the first half of the first tier of net sales was increased by a low single digit percentage. Should Servier’s rights and obligations under the Servier-Cellectis Agreement be assigned to the Company, each tier of royalty rates in the United States to Servier would be reduced by 10%, the ex-U.S. royalties to Servier would terminate, and the Company would assume Servier’s royalty obligations to Cellectis. In the absence of any such assignment, Servier will remain responsible for making royalty payments that may be due to Cellectis under the Servier-Cellectis Agreement. (5) Requires that the Company reconcile its net sales reports required to be delivered to Servier under the Servier Agreement at the end of each calendar year to the amount of net sales that would have been applicable if such net sales were calculated in accordance with International Financial Reporting Standards and requires that any shortfall or overpayment, as applicable, be paid by the Company to Servier or credited to the Company by Servier, as applicable. (6) The parties agreed that co-development performed by the Company and Servier under the Servier Agreement, including all development performed by Servier and for product candidates that the Company was co-developing with Servier (for which specified development costs were split with Allogene responsible for 60% and Servier responsible for 40%), including the CD19 Products, ceased as of December 15, 2022, and that all development costs incurred by either party after that date shall be borne solely by such party. (7) As soon as practicable after the date of the Servier Amendment but in any event prior to the end of July 2024, the parties will also agree to a transition plan, including transition timing and allocation of costs, to either transfer the sponsorship of the Servier’s long-term follow-up study of patients previously exposed to its UCART19V1 product candidate from Servier to the Company or consolidate the patients in this study into another Company-sponsored long-term follow-up study. (8) The parties agreed to waive any and all outstanding claims that were asserted relating to alleged violations of the Servier Agreement, including all claims that such party was entitled to various payments or refunds from the other party under the Servier Agreement, and any and all claims that either party now has or may have in the future related to such outstanding claims, and mutual releases with respect to such claims were granted. California Institute for Regenerative Medicine Grant On April 26 2024, the Company was awarded a $15.0 million grant from the California Institute for Regenerative Medicine (CIRM) to support the clinical development of ALLO-316, an AlloCAR T TM investigational product targeting CD70 in development for the treatment of advanced or metastatic renal cell carcinoma (RCC). The grant was awarded in accordance with the CIRM Grants Administration Policy for Clinical Stage Projects which may require the grant to be repaid by the Company.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the SEC. Accordingly, they do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the Company’s opinion, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation of the results of operations and cash flows for the periods presented have been included. The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Allogene Therapeutics, B.V. The subsidiary was dissolved on January 3, 2024. The condensed consolidated balance sheet as of March 31, 2024, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023, the condensed consolidated statements of stockholders’ equity as of March 31, 2024 and 2023, the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023, and the financial data and other financial information disclosed in the notes to the condensed consolidated financial statements are unaudited. The results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the year ending December 31, 2024, or for any other future annual or interim period. These condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and related notes for the year ended December 31, 2023, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 14, 2024.
Use of Estimates	Use of Estimates The preparation of condensed 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 condensed consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying condensed 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.
Significant Accounting Policies	Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2024, as compared to the significant accounting policies described in Note 1 of the “Notes to Financial Statements” in the Company’s audited financial statements included in its Annual Report.
Recently Adopted Accounting Pronouncements and 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 condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted The Company continues to monitor new accounting pronouncements issued by the FASB and does not believe any accounting pronouncements issued through the date of this report will have a material impact on the Company's condensed consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis and Level of Inputs Used in Such Measurements by Major Security Type	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 March 31, 2024 and as of December 31, 2023 are presented in the following tables: March 31, 2024 Level 1 Level 2 Level 3 Fair Value (In thousands) Financial Assets: Money market funds (1) $ 45,019 $ — $ — $ 45,019 Commercial paper — 4,879 — 4,879 Corporate bonds — 109,071 — 109,071 U.S. treasury securities 203,676 — — 203,676 U.S. agency securities — 28,600 — 28,600 Total financial assets $ 248,695 $ 142,550 $ — $ 391,245 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)

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2024
Investments, All Other Investments [Abstract]
Schedule of Fair Value and Amortized Cost	The fair value and amortized cost of cash equivalents and available-for-sale securities by major security type as of March 31, 2024 and as of December 31, 2023 are presented in the following tables: March 31, 2024 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) Money market funds $ 45,019 $ — $ — $ 45,019 Commercial paper 4,886 — (7) 4,879 Corporate bonds 109,188 31 (148) 109,071 U.S. treasury securities 203,894 2 (220) 203,676 U.S. agency securities 28,741 2 (143) 28,600 Total cash equivalents and investments $ 391,728 $ 35 $ (518) $ 391,245 Classified as: Cash equivalents $ 45,019 Short-term investments 333,821 Long-term investments 12,405 Total cash equivalents and investments $ 391,245 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

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Property and Equipment	Property and Equipment consist of the following: March 31, December 31, (In thousands) Leasehold improvements 108,621 108,621 Laboratory equipment 33,162 33,157 Computer equipment and purchased software 4,663 4,663 Furniture and fixtures 4,124 4,121 Total 150,570 150,562 Less: accumulated depreciation (54,639) (51,084) Total property and equipment, net $ 95,931 $ 99,478

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Schedule of Lease Liabilities	The balance sheet classification of our lease liabilities were as follows (in thousands): March 31, 2024 December 31, 2023 Operating lease liabilities Current portion included in accrued and other current liabilities $ 6,930 $ 6,775 Long-term portion of lease liabilities 88,916 88,346 Total operating lease liabilities $ 95,846 $ 95,121
Schedule of Lease Costs	The components of lease costs for operating leases, which were recognized in operating expenses, were as follows (in thousands): Three Months Ended 2024 2023 Operating lease cost $ 3,020 $ 3,181 Variable lease cost 867 691 Total lease costs $ 3,887 $ 3,872
Summary of Future Lease Payments Under Lease Liability	The undiscounted future non-cancellable lease payments under the Company's operating leases as of March 31, 2024 were as follows: Year ending December 31: (In thousands) 2024 (remaining 9 months) $ 9,436 2025 12,920 2026 13,163 2027 13,612 2028 14,076 2029 and thereafter 65,385 Total undiscounted lease payments 128,592 Less: Present value adjustment (32,746) Total $ 95,846

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2024
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- Aggregate Intrinsic Value (in years) (in thousands) Balance, December 31, 2023 21,812,946 $ 9.93 7.53 $ 662 Options granted 4,259,396 3.22 9.50 Options exercised (350,118) 2.27 $ 584 Options forfeited (1,696,808) 10.68 Balance, March 31, 2024 24,025,416 $ 8.80 7.80 $ 7,516 Exercisable, March 31, 2024 17,689,533 $ 9.97 7.43 $ 2,262 Vested and expected to vest, March 31, 2024 24,025,416 $ 8.80 7.80 $ 7,516
Schedule Stock Option 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: Three Months Ended March 31, 2024 2023 Expected term in years 5.85 - 6.06 6.03 - 6.07 Expected volatility 73.50% 73.85% Expected risk-free interest rate 3.94% - 4.22% 3.45% - 4.10% Expected dividend 0% 0%
Schedule of Restricted Stock Units Activity Under Plan	The following summarizes restricted stock unit activity under the 2018 Plan: Outstanding Restricted Stock Units Restricted Stock Units Weighted- Weighted Average Remaining Vesting Life Aggregate Intrinsic Value (in years) (in thousands) Unvested December 31, 2023 12,180,471 $ 6.68 2.00 $ 39,099 Granted 4,046,261 4.44 1.85 Vested (1,170,889) 9.82 Forfeited (1,446,452) 8.78 Unvested March 31, 2024 13,609,391 $ 5.52 1.98 $ 60,834 Vested and expected to vest, March 31, 2024 13,609,391 $ 5.52 1.98 $ 60,834

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Schedule of Potentially Dilutive Shares	The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share for the period presented due to their anti-dilutive effect: March 31, 2024 2023 Stock options to purchase common stock 24,025,416 23,548,486 Restricted stock units subject to vesting 13,609,391 13,587,470 Expected shares to be purchased under Employee Stock Purchase Plan 1,077,525 1,234,606 Early exercised stock options subject to future vesting — 105,743 Total 38,712,332 38,476,305

Description of Business (Detail

Description of Business (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents and marketable securities	$ 397,300
Accumulated deficit	$ 1,627,233	$ 1,562,233

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - Fair Value, Measurements, Recurring - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 391,245,000	$ 444,078,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Financial liabilities	$ 0	$ 0

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 391,245,000	$ 444,078,000
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	45,019,000	78,536,000
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	4,879,000
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	109,071,000	97,166,000
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	203,676,000	229,516,000
U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	28,600,000	38,860,000
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	248,695,000	308,052,000
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	45,019,000	78,536,000
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	203,676,000	229,516,000
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	142,550,000	136,026,000
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	4,879,000
Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	109,071,000	97,166,000
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	28,600,000	38,860,000
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

Financial Instruments - Cash Eq

Financial Instruments - Cash Equivalents, Restricted Cash and Investments, Classified as Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 391,728	$ 444,589
Unrealized Gains	35	245
Unrealized Losses	(518)	(756)
Cash equivalents	45,019	78,536
Short-term investments	333,821	365,542
Long-term investments	12,405	0
Total cash equivalents and investments	391,245	444,078
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45,019	78,536
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	45,019	78,536
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,886
Unrealized Gains	0
Unrealized Losses	(7)
Fair Value	4,879
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	109,188	97,265
Unrealized Gains	31	113
Unrealized Losses	(148)	(212)
Fair Value	109,071	97,166
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	203,894	229,563
Unrealized Gains	2	132
Unrealized Losses	(220)	(179)
Fair Value	203,676	229,516
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	28,741	39,225
Unrealized Gains	2	0
Unrealized Losses	(143)	(365)
Fair Value	$ 28,600	$ 38,860

Financial Instruments - Additio

Financial Instruments - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Investments, All Other Investments [Abstract]
Maximum remaining contractual maturities of available-for-sale securities (in years)	2 years
Realized losses on available-for-sale securities	$ 0	$ 1
Net unrealized loss position	29.4		$ 48.4
Accrued interest receivable from available-fore-sale investments	$ 1.7		$ 1.7

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 150,570	$ 150,562
Less: accumulated depreciation	(54,639)	(51,084)
Total property and equipment, net	95,931	99,478
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	108,621	108,621
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	33,162	33,157
Computer equipment and purchased software
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	4,663	4,663
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 4,124	$ 4,121

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - Reduction To Workforce - USD ($) $ in Millions		3 Months Ended
	Jan. 04, 2024	Mar. 31, 2024
Restructuring Cost and Reserve [Line Items]
Positions eliminated, percent	22%
Payments for restructuring		$ 2.6
Restructuring reserve		$ 0.4

License and Collaboration Agr_2

License and Collaboration Agreements - Pfizer (Details) - Pfizer - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty obligation period from date of first sale	12 years
Asset Contribution Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target	$ 325,000,000
Milestone payments	0	$ 0
Minimum | Asset Contribution Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target	30,000,000
Maximum | Asset Contribution Agreement
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

License and Collaboration Agr_3

License and Collaboration Agreements - Cellectis (Details)	3 Months Ended
	Mar. 31, 2024 USD ($) country product	Mar. 31, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development	$ 52,259,000	$ 80,238,000
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
Collaborative agreement, breech of obligation, period to cure	90 days
Collaborative agreement, company's right to terminate, period to provide written notice	60 days
Collaborative agreement, option to terminate, period after material breech	90 days
Collaborative agreement, option to terminate, period after change in control	60 days
Cellectis | 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
Cellectis | Research Collaboration And License Agreement | Development And Sales | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target	$ 2,800,000,000
Number of products to commercialize | product	1
Number of countries to commercialize product | country	1

License and Collaboration Agr_4

License and Collaboration Agreements - Servier (Details) - Servier - License and Collaboration Agreement € in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) product	Mar. 31, 2023 USD ($)	Mar. 31, 2024 EUR (€) product	Dec. 31, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of products to develop | product	1		1
Development costs payable by the Company (in percent)	60%
Development cost payable by collaboration partner (in percent)	40%
Net cost recoveries	$ 0	$ 0.2
Other receivables	0			$ 0
Regulatory Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone receivable	42
Sales Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone receivable	76.1		€ 70.5
Maximum | Regulatory Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target	137.5
Maximum | Sales Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target	$ 78

License and Collaboration Agr_5

License and Collaboration Agreements - Notch Therapeutics (Details)		1 Months Ended		3 Months Ended
	Nov. 01, 2019 USD ($)	Oct. 31, 2021 USD ($)	Feb. 28, 2021 USD ($)	Mar. 31, 2024 USD ($) target	Mar. 31, 2023 USD ($)	Jan. 25, 2024 USD ($)	Dec. 31, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investments				$ 2,716,000			$ 3,645,000
Research and development				$ 52,259,000	$ 80,238,000
Notch Therapeutics, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investments	$ 5,000,000
Ownership percentage	25%
Payments for additional investment in interest		$ 1,800,000	$ 15,900,000
Notch Therapeutics, Inc. | Voting Interest
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage		23%	20.70%
Notch Therapeutics, Inc. | Research and Development Expense
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaborative agreement, company's right to terminate, period to provide written notice				90 days
Collaboration costs				$ 0	1,000,000
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
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				7,250,000
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
Notch Therapeutics, Inc. | Amended And Restated Collaboration And License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable						$ 30,000,000
Number of released targets out-licensed | target				0

License and Collaboration Agr_6

License and Collaboration Agreements - MD Anderson Cancer Center (Details) - USD ($) $ in Millions			3 Months Ended		12 Months Ended
	Jan. 03, 2024	Oct. 06, 2020	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2020
Foresight Diagnostics Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Committed funding	$ 26.2
University Of Texas M D Anderson Cancer Center
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration agreement, term (in years)		5 years
Committed funding		$ 15
Collaboration agreement, upfront payment					$ 3	$ 3
University Of Texas M D Anderson Cancer Center | Research and Development Expense
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration costs			$ 0.1	$ 0.4

License and Collaboration Agr_7

License and Collaboration Agreements - Allogene Overland Biopharm (CY) Limited (Details) - USD ($)		3 Months Ended
	Dec. 14, 2020	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration revenue - related party		$ 22,000	$ 30,000
Allogene Overland, Allogene Overland BioPharm (HK) Limited
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration revenue - related party		100,000	100,000
Reduction to research and development expense		0	$ 0
Allogene Overland
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage	49%
Equity method investments		$ 0		$ 0
Allogene Overland | Overland Pharmaceuticals Inc. | Joint Venture
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%
Annual discount rate	11.90%
Allogene Overland | Allogene Overland, Allogene Overland BioPharm (HK) Limited | Joint Venture
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payments per target	$ 40,000,000
Fair value	79,000,000
Collaboration agreement, upfront payment	40,000,000
Initial transaction price	119,000,000
Joint steering committee participation	600,000
Allogene Overland | Allogene Overland, Allogene Overland BioPharm (HK) Limited | Joint Venture | Intellectual Property
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Initial transaction price	114,000,000
Allogene Overland | Allogene Overland, Allogene Overland BioPharm (HK) Limited | Joint Venture | Manufacturing License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Initial transaction price	2,300,000
Allogene Overland | Allogene Overland, Allogene Overland BioPharm (HK) Limited | Joint Venture | Future Intellectual Property
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Initial transaction price	$ 2,100,000
Allogene Overland | Overland Pharmaceuticals Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage	51%

License and Collaboration Agr_8

License and Collaboration Agreements - Antion (Details) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 05, 2022 USD ($) product	Jul. 31, 2023 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment for investment in stock			$ 81,131	$ 35,094
Antion
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Warrants and rights outstanding		$ 3,000
Antion Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration agreement, upfront payment	$ 3,500
Prior investment obligation		3,000
Collaboration costs			0	$ 500
Antion Collaboration Agreement | Current Accrued and Other Liabilities
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration costs			0		$ 0
Antion Collaboration Agreement | Other Noncurrent Assets
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity investment, total			$ 0		$ 0
Antion Collaboration Agreement | Preferred Stock
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment for investment in stock	3,000
Preferred stock investment payable		$ 2,000
Antion Collaboration Agreement, Milestone Achievement One
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable	$ 35,300
Number of products to develop | product	4
Antion Collaboration Agreement, Milestone Achievement Two
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate potential milestone payable	$ 2,000

License and Collaboration Agr_9

License and Collaboration Agreements - Foresight Diagnostics (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 03, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development		$ 52,259	$ 80,238
Accrued and other current liabilities		25,029		$ 31,096
Foresight Diagnostics Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Committed funding	$ 26,200
Research and development		500
Foresight Diagnostics Collaboration Agreement | Current Accrued and Other Liabilities
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Accrued and other current liabilities		$ 0		$ 700

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended	3 Months Ended
	Feb. 28, 2019 ft² renewal	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Feb. 28, 2023	Dec. 31, 2021 ft²	Dec. 31, 2020 USD ($)	Jul. 31, 2020 USD ($)	Dec. 31, 2018	Oct. 31, 2018 USD ($) ft²	Aug. 31, 2018 ft²
Operating Leased Assets [Line Items]
Area of office and laboratory (in square feet) | ft²									14,943	68,000
Operating lease term									124 months	127 months
Operating lease, option to extend term (in years)									7 years	7 years
Tenant improvements						$ 5
Additional area of new office building | ft²					47,566
Allowance for tenant improvements									$ 0.8
Letter of credit		$ 6	$ 6
Cash paid for amounts included in measurement of lease liabilities		$ 3.1
Weighted average discount rate (as a percent)		6.24%
Weighted average remaining lease term (in years)		8 years 9 months 25 days
Agreement term							20 years
Termination payment							$ 4.3
Non-cancellable purchase commitments		$ 0.9
Bellco | Sublease Agreement | Related Party
Operating Leased Assets [Line Items]
Sublease, term of contract (in years)				115 months				3 years
Lease One, Amended
Operating Leased Assets [Line Items]
Operating lease term					120 months
Operating lease, option to extend term (in years)					8 years
Lease Two
Operating Leased Assets [Line Items]
Operating lease, option to extend term (in years)									8 years
Letter of Credit
Operating Leased Assets [Line Items]
Letter of credit		4.3	$ 4.3
Newark
Operating Leased Assets [Line Items]
Operating lease term	188 months
Operating lease, option to extend 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

Commitments and Contingencies_2

Commitments and Contingencies - Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued and other current liabilities	Accrued and other current liabilities
Current portion included in accrued and other current liabilities	$ 6,930	$ 6,775
Long-term portion of lease liabilities	88,916	88,346
Total operating lease liabilities	$ 95,846	$ 95,121

Commitments and Contingencies_3

Commitments and Contingencies - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 3,020	$ 3,181
Variable lease cost	867	691
Total lease costs	$ 3,887	$ 3,872

Commitments and Contingencies_4

Commitments and Contingencies - Undiscounted Future Lease Payments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
2024 (remaining 9 months)	$ 9,436
2025	12,920
2026	13,163
2027	13,612
2028	14,076
2029 and thereafter	65,385
Total undiscounted lease payments	128,592
Less: Present value adjustment	(32,746)
Total	$ 95,846	$ 95,121

Equity Method Investments (Deta

Equity Method Investments (Details) - USD ($)		1 Months Ended		3 Months Ended
	Nov. 01, 2019	Oct. 31, 2021	Feb. 28, 2021	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 14, 2020
Schedule of Equity Method Investments [Line Items]
Equity method investments				$ 2,716,000		$ 3,645,000
Notch Therapeutics, Inc.
Schedule of Equity Method Investments [Line Items]
Payments to acquire interest in Notch	$ 5,100,000
Transaction cost	$ 100,000
Ownership percentage	25%
Payments for additional investment in interest		$ 1,800,000	$ 15,900,000
Equity method investments	$ 5,000,000
Share of loss from equity method investments				900,000	$ 1,700,000
Notch Therapeutics, Inc. | Voting Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage		23%	20.70%
Allogene Overland
Schedule of Equity Method Investments [Line Items]
Ownership percentage							49%
Share of loss from equity method investments				0	$ 1,200,000
Carrying value				$ 0		$ 0

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Millions		3 Months Ended		12 Months Ended
	Jul. 19, 2022 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) $ / shares shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 shares	Jun. 21, 2022 employee shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares as percentage of common shares outstanding		5%
Number of shares reserved for future issuance (in shares)		9,738,364
Plan modification, incremental cost | $	$ 5.2
Expected dividend		0%
Stock-based compensation | $		$ 11.9	$ 18.8
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Unrecognized stock based compensation expense | $		$ 52.4
Unrecognized stock based compensation expense, weighted average recognition period (in years)		2 years 4 months 24 days
Restricted stock units, granted (in shares)		4,046,261
Stock options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Exchange offer, number of employees | employee					199
Exchange offer, number of options accepted for cancellation (in shares)					3,666,600
Exchange offer, number of options accepted for cancellation (in shares)					0.935
Number of options, options granted (in shares)	3,666,600
Weighted average exercise price (in dollars) | $ / shares	$ 13.31
Expiration period	7 years
Grants in period, weighted average grant date fair value (in dollars per share) | $ / shares		$ 2.15
Unrecognized stock based compensation expense | $		$ 54
Unrecognized stock based compensation expense, weighted average recognition period (in years)		2 years 4 months 24 days
Performance-Based Restricted Stock Units | Certain Executive Officers And Other Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, granted (in 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]
Restricted stock units, granted (in shares)				2,189,125
Stock-based compensation | $		$ 0.7	$ 0.1
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option grant period		10 years
Option exercise price as percentage of fair value of common stock on grant date		100%
Option exercise price as percentage of fair value of common stock on grant date		110%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Combined voting power by individual (as a percent)		10%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - 2018 Plan - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Number of Options
Number of options, beginning balance (in shares)	21,812,946
Number of options, options granted (in shares)	4,259,396
Number of options, options exercised (in shares)	(350,118)
Number of options, options forfeited (in shares)	(1,696,808)
Number of options, ending balance (in shares)	24,025,416	21,812,946
Number of options, exercisable (in shares)	17,689,533
Number of options, vested and expected to vest (in shares)	24,025,416
Weighted- Average Exercise Price
Weighted-average exercise price, beginning balance (in dollars per share)	$ 9.93
Weighted-average exercise price, options granted (in dollars per share)	3.22
Weighted-average exercise price, options exercised (in dollars per share)	2.27
Weighted-average exercise price, options forfeited (in dollars per share)	10.68
Weighted-average exercise price, ending balance (in dollars per share)	8.80	$ 9.93
Weighted-average exercise price, exercisable (in dollars per share)	9.97
Weighted-average exercise price, vested and expected to vest (in dollars per share)	$ 8.80
Weighted-average remaining contract term, outstanding (in years)	7 years 9 months 18 days	7 years 6 months 10 days
Weighted-average remaining contract term, granted (in years)	9 years 6 months
Weighted-average remaining contract term, exercisable (in years)	7 years 5 months 4 days
Weighted-average remaining contract term, vested and expected to vest (in years)	7 years 9 months 18 days
Aggregate intrinsic value, balance	$ 7,516	$ 662
Aggregate intrinsic value, exercised	584
Aggregate intrinsic value, exercisable	2,262
Aggregate intrinsic value, vested and expected to vest	$ 7,516

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions (Details)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend	0%
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	73.50%	73.85%
Expected risk-free interest rate, minimum	3.94%	3.45%
Expected risk-free interest rate, maximum	4.22%	4.10%
Expected dividend	0%	0%
2018 Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	5 years 10 months 6 days	6 years 10 days
2018 Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	6 years 21 days	6 years 25 days

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Unit - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Restricted Stock Units
Restricted stock units, unvested, beginning balance (in shares)	12,180,471
Restricted stock units, granted (in shares)	4,046,261
Restricted stock units, vested (in shares)	(1,170,889)
Restricted stock units, forfeited (in shares)	(1,446,452)
Restricted stock units, unvested, ending balance (in shares)	13,609,391	12,180,471
Restricted stock units, vested and expected to vest (in shares)	13,609,391
Weighted- Average Grant Date Fair Value per Share
Weighted-average fair value at date of grant per share, beginning balance (in dollars per share)	$ 6.68
Weighted-average fair value at date of grant per share, granted (in dollars per share)	4.44
Weighted-average fair value at date of grant per share, vested (in dollars per share)	9.82
Weighted-average fair value at date of grant per share, forfeited (in dollars per share)	8.78
Weighted-average fair value at date of grant per share, ending balance (in dollars per share)	5.52	$ 6.68
Weighted-average fair value at date of grant per share, vested and expected to vest (in dollars per share)	$ 5.52
Weighted average remaining vesting life, unvested (in years)	1 year 11 months 23 days	2 years
Weighted average remaining vesting life, granted (in years)	1 year 10 months 6 days
Weighted average remaining vesting life, vested and expected to vest (in years)	1 year 11 months 23 days
Aggregate intrinsic value, unvested	$ 60,834	$ 39,099
Aggregate intrinsic value, vested and expected to vest	$ 60,834

Related Party Transactions (Det

Related Party Transactions (Details)	1 Months Ended				3 Months Ended
	Feb. 28, 2023 ft²	Jul. 31, 2022 ft²	Dec. 31, 2018 ft²	Aug. 31, 2018 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Related Party Transaction [Line Items]
Collaboration revenue - related party					$ 22,000	$ 30,000
Operating lease right-of-use asset					64,483,000		$ 63,703,000
Operating lease liability					95,846,000		$ 95,121,000
Allogene Overland
Related Party Transaction [Line Items]
Share of loss from equity method investments					0	1,200,000
Allogene Overland, Allogene Overland BioPharm (HK) Limited
Related Party Transaction [Line Items]
Collaboration revenue - related party					100,000	100,000
Bellco | Sublease Agreement | Related Party
Related Party Transaction [Line Items]
Area of office space (in square feet) | ft²	2,218	737	1,293
Sublease, term of contract (in months)	115 months		3 years
Operating lease right-of-use asset					2,400,000
Operating lease liability					2,400,000
Non-cash rent expense					100,000
Bellco | Consulting Agreements | Related Party
Related Party Transaction [Line Items]
Cost of revenue					$ 200,000	200,000
Bellco | Consulting Agreements | Related Party | Maximum
Related Party Transaction [Line Items]
Related party transaction compensation percentage				60%
Bellco | Consulting Agreements | Related Party | Payments Commencing January 2022
Related Party Transaction [Line Items]
Related party transaction monthly payment in arrears				$ 40,217
Two River | Consulting Agreements | Related Party
Related Party Transaction [Line Items]
Cost of revenue						$ 100,000

Net Loss Per Share (Details)

Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	38,712,332	38,476,305
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)	24,025,416	23,548,486
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)	13,609,391	13,587,470
Expected shares to be 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)	1,077,525	1,234,606
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)	0	105,743

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event € in Millions, $ in Millions	May 10, 2024 EUR (€)	Apr. 26, 2024 USD ($)
California Institute For Regenerative Medicine (CIRM)
Subsequent Event [Line Items]
Grant award, amount | $		$ 15
License and Collaboration Agreement | Servier
Subsequent Event [Line Items]
Development costs payable by the Company (in percent)	60%
Development cost payable by collaboration partner (in percent)	40%
License and Collaboration Agreement | UNITED STATES | Servier
Subsequent Event [Line Items]
Royalty rate, percent	10%
Reduction to royalty rate, percent	10%
Regulatory Milestone | License and Collaboration Agreement | Servier
Subsequent Event [Line Items]
Aggregate milestone payments	€ 75
Aggregate potential milestone payments, remaining obligation	60
Milestone payable per indication	55
Aggregate potential milestone payable	20
Sales Milestone | License and Collaboration Agreement | Servier
Subsequent Event [Line Items]
Aggregate milestone payments	€ 80