Allogene Therapeutics (ALLO) 10-Q 7 Nov 24 2024 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2024	Nov. 01, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 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)		209,672,091
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Central Index Key	0001737287
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 51,239	$ 83,155
Short-term investments	240,325	365,542
Prepaid expenses and other current assets	12,851	10,418
Total current assets	304,415	459,115
Long-term investments	111,821	0
Operating lease right-of-use asset	46,313	63,703
Property and equipment, net	88,989	99,478
Deposit placed in escrow	22,320	0
Restricted cash	10,292	10,292
Other long-term assets	4,970	6,604
Equity method investments	0	3,645
Total assets	589,120	642,837
Current liabilities:
Accounts payable	5,506	5,897
Accrued and other current liabilities	27,065	31,182
Total current liabilities	32,571	37,079
Operating lease liability, noncurrent	85,135	88,346
Other long-term liabilities	7,666	5,179
Total liabilities	125,372	130,604
Commitments and Contingencies (Notes 6 and 7)
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 shares authorized as of September 30, 2024 and December 31, 2023; no shares were issued and outstanding as of September 30, 2024 and December 31, 2023	0	0
Common stock, $0.001 par value: 400,000,000 shares authorized as of September 30, 2024 and December 31, 2023; 209,500,137 and 168,642,238 shares issued and outstanding as of September 30, 2024 and December 31, 2023, respectively	210	169
Additional paid-in capital	2,223,265	2,075,252
Accumulated deficit	(1,759,884)	(1,562,233)
Accumulated other comprehensive income/(loss)	157	(955)
Total stockholders’ equity	463,748	512,233
Total liabilities and stockholders’ equity	$ 589,120	$ 642,837

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 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)	209,500,137	168,642,238
Common stock, shares outstanding (in shares)	209,500,137	168,642,238

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues
Collaboration revenue - related party	$ 0	$ 22	$ 22	$ 74
Operating expenses:
Research and development	44,713	45,977	147,327	188,253
General and administrative	16,333	17,041	49,687	54,449
Impairment of long-lived assets	10,728	0	15,717	0
Total operating expenses	71,774	63,018	212,731	242,702
Loss from operations	(71,774)	(62,996)	(212,709)	(242,628)
Other income (expense), net:
Interest and other income, net	6,705	6,205	17,126	12,042
Interest expense	(100)	0	(100)	0
Other income and (expense), net	(1,124)	(5,496)	(1,968)	(10,901)
Total other income (expense), net	5,481	709	15,058	1,141
Net loss	(66,293)	(62,287)	(197,651)	(241,487)
Other comprehensive loss:
Net unrealized gain on available-for-sale investments	937	1,440	1,112	7,515
Net comprehensive loss	$ (65,356)	$ (60,847)	$ (196,539)	$ (233,972)
Net loss per share, basic (in dollars per share)	$ (0.32)	$ (0.37)	$ (1.04)	$ (1.58)
Net loss per share, diluted (in dollars per share)	$ (0.32)	$ (0.37)	$ (1.04)	$ (1.58)
Weighted-average number of shares used in computing net loss per share, basic (in shares)	209,188,551	167,649,010	189,519,897	153,087,449
Weighted-average number of shares used in computing net loss per share, diluted (in shares)	209,188,551	167,649,010	189,519,897	153,087,449

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	ATM Offering	Public offering	Common Stock	Common Stock ATM Offering	Common Stock Public offering	Additional Paid-in Capital	Additional Paid-in Capital ATM Offering	Additional Paid-in Capital Public offering	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, 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]
Net loss	(241,487)
Net unrealized gain on available-for-sale investments	7,515
Ending balance (in shares) at Sep. 30, 2023				168,175,221
Ending balance at Sep. 30, 2023	580,635			$ 168			2,059,333			(1,476,455)	(2,411)
Beginning balance (in shares) at Mar. 31, 2023				145,740,333
Beginning balance at Mar. 31, 2023	592,010			$ 146			1,932,734			(1,334,936)	(5,934)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and vesting of RSUs (in shares)				1,105,001
Issuance of common stock upon exercise of stock options and vesting of RSUs	1,606			$ 1			1,605
Vesting of early exercised common stock	432						432
Stock-based compensation	16,594						16,594
Issuance of common stock, net of commissions and offering costs (in shares)					20,288,330
Issuance of common stock, net of commissions and offering costs		$ 87,918			$ 20			$ 87,898
Net loss	(79,232)									(79,232)
Net unrealized gain on available-for-sale investments	2,083										2,083
Ending balance (in shares) at Jun. 30, 2023				167,133,664
Ending balance at Jun. 30, 2023	621,411			$ 167			2,039,263			(1,414,168)	(3,851)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and vesting of RSUs (in shares)				204,116
Issuance of common stock upon exercise of stock options and vesting of RSUs	326			$ 0			326
Vesting of early exercised common stock	432						432
Stock-based compensation	15,354						15,354
Employee stock purchase plan (in shares)				231,206
Employee stock purchase plan	765			$ 0			765
Issuance of common stock, net of commissions and offering costs (in shares)					606,235
Issuance of common stock, net of commissions and offering costs		3,194			$ 1			3,193
Net loss	(62,287)									(62,287)
Net unrealized gain on available-for-sale investments	1,440										1,440
Ending balance (in shares) at Sep. 30, 2023				168,175,221
Ending balance at Sep. 30, 2023	$ 580,635			$ 168			2,059,333			(1,476,455)	(2,411)
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
Ending balance at Mar. 31, 2024	$ 461,367			$ 170			2,089,357			(1,627,233)	(927)
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]
Net loss	(197,651)
Net unrealized gain on available-for-sale investments	$ 1,112
Ending balance (in shares) at Sep. 30, 2024	209,500,137			209,500,137
Ending balance at Sep. 30, 2024	$ 463,748			$ 210			2,223,265			(1,759,884)	157
Beginning balance (in shares) at Mar. 31, 2024				170,452,967
Beginning balance at Mar. 31, 2024	461,367			$ 170			2,089,357			(1,627,233)	(927)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and vesting of RSUs (in shares)				415,483
Issuance of common stock upon exercise of stock options and vesting of RSUs	19			$ 1			18
Stock-based compensation	13,559						13,559
Issuance of common stock, net of commissions and offering costs (in shares)					250,000	37,931,035
Issuance of common stock, net of commissions and offering costs		$ 1,021	$ 105,283			$ 38		$ 1,021	$ 105,245
Net loss	(66,358)									(66,358)
Net unrealized gain on available-for-sale investments	147										147
Ending balance (in shares) at Jun. 30, 2024				209,049,485
Ending balance at Jun. 30, 2024	515,038			$ 209			2,209,200			(1,693,591)	(780)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and vesting of RSUs (in shares)				181,142
Issuance of common stock upon exercise of stock options and vesting of RSUs	0			$ 0			0
Stock-based compensation	13,387						13,387
Employee stock purchase plan (in shares)				269,510
Employee stock purchase plan	679			$ 1			678
Net loss	(66,293)									(66,293)
Net unrealized gain on available-for-sale investments	$ 937										937
Ending balance (in shares) at Sep. 30, 2024	209,500,137			209,500,137
Ending balance at Sep. 30, 2024	$ 463,748			$ 210			$ 2,223,265			$ (1,759,884)	$ 157

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders’ Equity (Parenthetical) - USD ($)	3 Months Ended
	Jun. 30, 2024	Sep. 30, 2023	Jun. 30, 2023
ATM Offering
Issuance costs		$ 50,000	$ 1,600,000
Public offering
Issuance costs	$ 4,700,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Cash flows from operating activities:
Net loss			$ (197,651)	$ (241,487)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation			38,870	50,718
Depreciation and amortization			10,406	10,722
Amortization/accretion on investment securities, net			(6,697)	(3,510)
Impairment of long-lived assets	$ 10,728	$ 0	15,717	0
Impairment of equity method investment			0	3,000
Non-cash rent expense			4,148	4,949
Non-cash collaboration revenue - related party			(14)	(49)
Share of gain/loss from equity method investments, net			1,688	7,866
Changes in operating assets and liabilities:
Deposit placed in escrow			(22,320)	0
Prepaid expenses and other current assets			(2,294)	3,555
Other long-term assets			3,591	(421)
Accounts payable			(537)	(7,200)
Accrued and other current liabilities			(4,142)	(7,109)
Operating lease liabilities			(4,531)	(4,445)
Other long-term liabilities			164	(615)
Net cash used in operating activities			(163,602)	(184,026)
Cash flows from investing activities:
Purchases of property and equipment			(437)	(1,335)
Proceeds from sales of investments			5,398	5,623
Proceeds from maturities of investments			330,294	461,467
Purchase of investments			(314,501)	(369,927)
Net cash provided by investing activities			20,754	95,828
Cash flows from financing activities:
Proceeds from CIRM award			2,280	0
Proceeds from issuance of common stock upon exercise of stock options			813	1,932
Proceeds from issuance of common stock under the employee stock purchase plan			1,535	2,496
Net cash provided by financing activities			110,932	95,540
Net change in cash and cash equivalents and restricted cash			(31,916)	7,342
Cash and cash equivalents and restricted cash — beginning of period			93,447	72,196	$ 72,196
Cash and cash equivalents and restricted cash — end of period	$ 61,531	$ 79,538	61,531	79,538	$ 93,447
Non-cash operating activities:
Right-of-use asset obtained in exchange for lease liability			2,409	0
Non-cash deferred revenue included in other long-term liabilities			3,079	0
Supplemental disclosure:
Cash paid for amounts included in the measurement of lease liabilities			(9,308)	(9,013)
ATM Offering
Cash flows from financing activities:
Proceeds from issuance of common stock, net of commissions and issuance of costs			1,021	91,112
Public offering
Cash flows from financing activities:
Proceeds from issuance of common stock, net of commissions and issuance of costs			$ 105,283	$ 0

Description of Business

Description of Business	9 Months Ended
	Sep. 30, 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. Registered Offering On May 13, 2024, the Company entered into (i) an underwriting agreement (Underwriting Agreement) with Goldman Sachs & Co. LLC (Underwriter) and (ii) a Securities Purchase Agreement (Securities Purchase Agreement) with certain members of the Company’s Board of Directors and executive officers or their respective affiliates (Purchasers), pursuant to which the Company sold and issued to the Underwriter and the Purchasers an aggregate of 37,931,035 shares of common stock of the Company at a purchase price of $2.90 per share, in a registered offering transaction (Registered Offering) for aggregate gross proceeds of $110.0 million, before deducting the underwriting discount and commissions and estimated offering expenses payable by the Company. The Registered Offering closed on May 16, 2024. The aggregate fee payable by the Company to the Underwriter was $4.7 million, plus the reimbursement of certain expenses. The Purchasers purchased an aggregate of 1,034,484 shares of common stock of the Company in the Registered Offering. 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 $403.4 million as of September 30, 2024. Since inception through September 30, 2024, the Company has incurred cumulative net losses of $1,759.9 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	9 Months Ended
	Sep. 30, 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 September 30, 2024, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2024 and 2023, the condensed consolidated statements of stockholders’ equity as of September 30, 2024 and 2023, the condensed consolidated statements of cash flows for the nine months ended September 30, 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 and nine months ended September 30, 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, the CIRM award liability 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 and nine months ended September 30, 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, with exception of the following. California Institute for Regenerative Medicine (CIRM) Award Accounting for the CIRM award does not fall under ASC 606, Revenue from Contracts and Customers, as CIRM does not meet the definition of a customer. No income associated with the CIRM award will be recognized until it is confirmed with CIRM that the award does not require repayment. Until then such award will be recognized, along with any interest, as a long-term liability upon cash receipt. Any estimated interest accrued for the CIRM award received is recognized as interest expense in the condensed consolidated statements of operations. See Note 5 below for more details. 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 In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (ASU 2023-07), which requires all public entities, including public entities with a single reportable segment, to provide in interim and annual periods one or more measures of segment profit or loss used by the chief operating decision maker to allocate resources and assess performance. Additionally, the standard requires disclosures of significant segment expenses and other segment items as well as incremental qualitative disclosures. The guidance in this update is effective for fiscal years beginning after December 15, 2023, and interim periods after December 15, 2024. The Company is currently in the process of evaluating the effects of this pronouncement on its related disclosures. In December 2023, the FASB issued Accounting Standard Update No. 2023-09, Income taxes (Topic 740), Improvement to income tax disclosures , which enhances the disclosures required for income taxes in the Company’s annual financial statements. This standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company does not plan to adopt this standard early. The adoption of this standard is not expected to have a material impact on the Company’s financial statements.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 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 September 30, 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 September 30, 2024 and as of December 31, 2023 are presented in the following tables: September 30, 2024 Level 1 Level 2 Level 3 Fair Value (In thousands) Financial Assets: Money market funds (1) $ 43,977 $ — $ — $ 43,977 Commercial paper — 36,840 — 36,840 Corporate bonds — 125,587 — 125,587 U.S. treasury securities 107,226 — — 107,226 U.S. agency securities — 72,813 — 72,813 Asset-backed securities — 9,680 — 9,680 Total financial assets $ 151,203 $ 244,920 $ — $ 396,123 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	9 Months Ended
	Sep. 30, 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 September 30, 2024 and as of December 31, 2023 are presented in the following tables: September 30, 2024 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) Money market funds $ 43,977 $ — $ — $ 43,977 Commercial paper 36,818 35 (13) 36,840 Corporate bonds 125,371 218 (2) 125,587 U.S. treasury securities 107,072 157 (3) 107,226 U.S. agency securities 72,617 196 — 72,813 Asset-backed securities 9,669 11 — 9,680 Total cash equivalents and investments $ 395,524 $ 617 $ (18) $ 396,123 Classified as: Cash equivalents $ 43,977 Short-term investments 240,325 Long-term investments 111,821 Total cash equivalents and investments $ 396,123 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 September 30, 2024, the remaining contractual maturities of available-for-sale securities were less than 3 years. There were no significant realized losses on available-for-sale securities for the three and nine months ended September 30, 2024. Realized losses on available-for-sale securities for the three and nine months ended September 30, 2023 were zero and $1.0 million, respectively. As of September 30, 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 September 30, 2024 and December 31, 2023, securities with a fair value of zero 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 September 30, 2024 and December 31, 2023, the Company recognized $2.8 million and $1.7 million, respectively, 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	9 Months Ended
	Sep. 30, 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: September 30, December 31, (In thousands) Leasehold improvements 107,545 108,621 Laboratory equipment 32,089 33,157 Computer equipment and purchased software 4,752 4,663 Furniture and fixtures 4,171 4,121 Total 148,557 150,562 Less: accumulated depreciation (59,568) (51,084) Total property and equipment, net $ 88,989 $ 99,478 The Company reviews for indicators of impairment on a quarterly basis which includes the change in how its property is being used. In June 2024, the Company made a decision to sublease one of its leased buildings in South San Francisco. The Company vacated and ceased occupancy of this building in June 2024 and currently the Company is actively marketing the leased building for sublease. The Company determined that the change in how this building is being used was an indicator of impairment. The Company identified this to-be-sublet property as a separate asset group. The Company concluded that the carrying value of this to-be-sublet property asset group was not recoverable and the estimated fair value of this asset group was below its carrying value. The decrease in the fair value of this asset group was mainly due to the lower estimated sublease income based on current commercial rental market conditions compared to the lease payments in accordance with the initial operating lease agreement. The Company applied a discounted cash flow method to estimate fair value of its right-of-use asset and leasehold improvements. Based on this analysis, the Company concluded the fair value of the right-of-use asset and leasehold improvements of $2.5 million was lower than its net book value of $7.5 million. The Company recognized a long-lived asset impairment charge of $5.0 million on the right-of-use asset and leasehold improvements in June 30, 2024. In September 2024, the Company identified an additional indicator that the carrying value of this to-be-sublet property asset group was not recoverable. The expected sublease rental income of $4.0 million as of June 30, 2024 had decreased to $1.9 million as of September 30, 2024. In addition, the risk-adjusted annual discount rate of 9.0% as of June 30, 2024 had increased to 9.5% as of September 30, 2024. The Company updated its discounted cash flow analysis to estimate fair value of its right-of-use asset and leasehold improvements. Based on this analysis, the Company concluded the fair value of the right-of-use asset and leasehold improvements of $1.2 million was lower than its net book value of $2.4 million. The Company recognized an additional long-lived asset impairment charge of $1.2 million on the right-of-use asset and leasehold improvements for the three months ended September 30, 2024 and recognized in aggregate long-lived asset impairment charges of $6.2 million on the right-of-use asset and leasehold improvements for the nine months ended September 30, 2024. Previously, in December 2023, the Company made a decision to sublease one of its other leased buildings in South San Francisco. The Company had vacated and ceased occupancy of this building in December 2023 and the Company is currently actively marketing the leased building for sublease. During the year ended December 31, 2023, the Company recognized long-lived asset impairment charge of $13.2 million on the right-of-use asset by applying a discounted cash flow method to estimate fair value of its right-of-use asset. The key inputs to this valuation were expected sublease rental income of $22.7 million through March 31, 2032 and annual discount rate of 9.0%. In September 30, 2024, the Company revised its valuation based on a non-binding letter of intent with a subtenant for a portion of the building and new market data. The expected sublease rental income based on the revised valuation was $4.7 million through March 31, 2032 and the annual discount rate did not change. The Company concluded the fair value of the right-of-use asset of $3.1 million was lower than its book value of $12.6 million and recognized an additional long-lived asset impairment charge of $9.5 million on the right-of-use asset for the three and nine months ended September 30, 2024. The determination of the fair values of the Company’s asset groups related to the to-be-sublet properties that are currently being marketed for sublease purposes represent Level 3 nonrecurring fair value measurements. Calculating the fair value of these assets involve significant estimates and assumptions. These estimates and assumptions include, among other things, expected sublease rental income and risk-adjusted annual discount rate. Changes in the factors and assumptions used could materially affect the amount of impairment loss recognized in the period an asset was considered impaired. 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 completed by June 30, 2024. During the nine months ended September 30, 2024, the Company paid approximately $2.9 million for severance and other employee benefits. As of September 30, 2024, $0.2 million of the severance and other employee benefits accrual was included in accrued and other current liabilities on the condensed consolidated balance sheet. CIRM Award On April 26, 2024, the Company was awarded up to $15.0 million from 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). Pursuant to terms of the award, the disbursements are tied to the achievement of specified operational milestones. In addition, the terms of the award include a co-funding requirement pursuant to which the Company is required to spend up to approximately $25.9 million of its own capital to fund the CIRM funded research project. The award was made in accordance with the CIRM Grants Administration Policy for Clinical Stage Projects which may require the award to be repaid by the Company. Under the terms of the CIRM award, the Company is obligated to pay royalties based on a low single digit royalty percentage on net sales of CIRM-funded product candidate. The maximum royalty that the Company may be required to pay to CIRM is equal to nine times the total amount awarded and paid to the Company. After completing the CIRM funded research project and at any time after the award period end date (but no later than the ten-year anniversary of the date of the award), the Company has the right, upon its election, to convert the award into a loan. The terms of conversion into a loan will be determined based on various factors and could result in 80% to 100% plus interest at 10% per annum plus the Secured Overnight Financing Rate of the total award dependent upon the phase of clinical development of the product candidate at the time of the Company's election to be repaid to CIRM. No income associated with the CIRM award will be recognized until it is confirmed with CIRM that the award does not require repayment. Upon cash receipt, the CIRM award and accrued interest will be recognized as other long-term liabilities on the Company’s balance sheet. The Company received $2.3 million from CIRM through September 30, 2024 and accounted for the proceeds as a liability within other long-term liabilities on the condensed consolidated balance sheet. During the three and nine months ended September 30, 2024, the Company recorded interest expense of $0.1 million. As of September 30, 2024, $0.1 million of accrued interest was included in other long-term liabilities.

License and Collaboration Agree

License and Collaboration Agreements	9 Months Ended
	Sep. 30, 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. 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 and nine months ended September 30, 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, 2015, 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 and nine months ended September 30, 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 Original 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 Original Servier Agreement, the Company has an exclusive license to develop, manufacture and commercialize licensed products directed against CD19, including UCART19, ALLO-501 and cemacabtagene ansegedleucel (cema-cel, previously ALLO-501A) (collectively, CD19 Products) 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. On May 10, 2024, the Company and Servier entered into an Amendment and Settlement Agreement (the Servier Amendment) which restructured the parties’ relationship under the Original Servier Agreement (as amended, the Servier Agreement). 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 Original Servier Agreement to elect a conversion of its license to the CD19 Products to a worldwide license. Under the Servier Agreement, the Company is required to use commercially reasonable efforts to develop, manufacture and commercialize a CD19 Product. Under the Servier Agreement, Servier sublicenses to the Company certain rights which Servier licenses from Cellectis pursuant to a License, Development and Commercialization Agreement by and between Cellectis and Servier, dated February 7, 2014, as amended by Amendment No. 1 to the License, Development and Commercialization Agreement, dated March 4, 2020 (as amended, the Servier-Cellectis Agreement). As amended by the Servier Amendment, all of the Company’s future milestone payments (regulatory and sales) under the Original Servier Agreement were modified to be the same as, and to coincide with, Servier’s milestone payments to Cellectis that are required under the Servier-Cellectis Agreement. The Servier Agreement provides for aggregate potential milestone payments by the Company to Servier of up to €75.0 million upon successful completion of various regulatory milestones and first commercial sale milestones in the United States, European Union and the United Kingdom for the initial indication of each licensed product, of which €60.0 million remains for the initial indication for cema-cel, with additional payments of €55.0 million, due for each subsequent indication, of which €50.0 million remains for the first subsequent indication for cema-cel, 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 obligations 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. The Company transferred €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 for the initial indication for cema-cel. 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. The Company is obligated 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 as compared to the Original Servier Agreement. 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. 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 under the Original Servier Agreement with the Company 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. The parties agreed to waive any and all outstanding claims that were asserted relating to alleged violations of the Original Servier Agreement, including all claims that such party was entitled to various payments or refunds from the other party under the Original 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. The Company will recognize expense related to the revised milestones and royalties when payments become probable. There was no gain or loss related to the expanded license territories and ceased Servier co-development. For the three and nine months ended September 30, 2024, the Company recorded zero and $5.4 million, respectively, in research and development expenses upon achievement of a regulatory milestone. For the three and nine months ended September 30, 2023, the Company recorded $0.1 million and $0.4 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 September 30, 2024, the Company recorded €20.0 million as deposit placed in escrow 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 served 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% on a voting interest basis. On May 17, 2024, Notch closed a Series B preferred stock financing with a combination of new and existing investors (Notch Series B Financing). The Company did not participate in the Notch Series B Financing but received Series B preferred stock as part of its anti-dilution rights. Immediately following this transaction, the Company’s share in Notch was 13%. In connection with the Notch Series B Financing, the Company waived its right to appoint one member of the Notch board of directors, but retained board observation rights. The Company no longer has any significant influence over Notch and as a result of the decrease in ownership and influence, accounted for its investment in Notch as an equity investment measured at cost less any impairment effective May 17, 2024. 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 September 30, 2024, no Released Targets were out-licensed by Notch. On May 17, 2024, in connection with the Notch Series B Financing the Company waived certain of its anti-dilution rights in exchange for a low single digit percentage reduction in the royalty rate for the royalties the Company is obliged to pay to Notch under our Notch intellectual property license should the Company commercialize a licensed product. For the three and nine months ended September 30, 2024, the Company recorded zero collaboration costs. For the three and nine months ended September 30, 2023, the Compan y recorded zero and $1.8 million, respective ly, in collaboration costs as research and development expenses. For the three and nine months ended September 30, 2023, the Company recorded $3.0 million in other expenses as impairment loss on its equity method investment in Notch. No milestones were achieved by Notch for the three and nine months ended September 30, 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 advance payment of $3.0 million to MD Anderson in the year ended December 31, 2020 and made an additional advance 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 and nine months ended September 30, 2024, the Company recorded $0.8 million and $1.1 million, respectively, in collaboration costs as research and development expenses. For the three and nine months ended September 30, 2023, the Company recorded $0.2 million and $1.2 million, respectively, in collaboration costs as research and development expenses. Investment in and License Agreement with Overland Therapeutics, Inc. Allogene Overland Biopharm (CY) Limited (Allogene Overland), later renamed Overland Therapeutics Inc. (Overland Therapeutics), was initially established as a joint venture by the Company and Overland Pharmaceuticals (CY) Inc. (Overland) pursuant to a Share Purchase Agreement (Share Purchase Agreement), dated December 14, 2020. Concurrently, on December 14, 2020, the Company entered into a License Agreement (License Agreement) with Allogene Overland 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. The Company received $40.0 million from Allogene Overland as partial consideration for the License Agreement. Until the Organizational Restructuring (as defined below), the Company and Overland were the sole equity holders in Allogene Overland. 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 (Overland Licensed Products), 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 (Allogene Overland PRC). On May 24, 2024, the Company, Overland, and Allogene Overland entered into a Share Exchange Agreement (Share Exchange Agreement) pursuant to which Overland’s cell therapy business merged into Allogene Overland (the Organizational Restructuring). Under the Share Exchange Agreement, Allogene Overland acquired from Overland a 100% equity interest in Overland Pharmaceuticals (US) Inc. (Overland US). Overland US includes certain research and development, clinical, and general and administrative staff, as well as select cell therapy assets, including its lead program, OL-101, an autologous GPRC5D-BCMA bispecific dual targeting CAR T for refractory multiple myeloma. Upon completion of the closing of the share exchange, Overland US became a wholly owned subsidiary of Allogene Overland, Overland’s ownership increased to 82% and the Company’s ownership decreased to 18%. Under a separate agreement between Overland and HH BioPharma Holdings Ltd. (HBP) executed on May 24, 2024, Overland distributed all Series Seed Preferred Shares of Allogene Overland held by Overland to HBP and HBP has assumed all rights and obligations attached to such shares and all rights and obligations of Overland under the Share Exchange Agreement. In connection with the Organizational Restructuring, on May 24, 2024, the Company and Allogene Overland PRC, entered into a First Amendment to the License Agreement (the License Amendment) to amend and supplement certain provisions of the License Agreement. Under the License Amendment, the Company continues to grant Allogene Overland PRC an exclusive license to develop, manufacture, and commercialize the Licensed Products in the JV Territory, with the Company retaining exclusive rights to the Licensed Products outside the JV Territory, and the royalty obligations to the Company were amended to a flat mid single-digit royalty on net sales in the JV Territory that are no longer subject to reductions. The License Amendment also provides the Company with additional rights to terminate the License Agreement in its entirety or with respect to the relevant Overland Licensed Products if Allogene Overland PRC fails to initiate manufacturing technology transfer with respect to an Overland Licensed Product as agreed in the License Amendment, or if HBP commits a funding default or a material breach of its representations, warranties, or covenants under the Share Exchange Agreement. The License Amendment also provides that the License Agreement will terminate automatically if the Company’s ownership in Allogene Overland falls below 7.5% (other than due to the Company’s sale of the shares of Allogene Overland), unless at that time Allogene Overland PRC and the Company have mutually agreed on the manufacturing technology transfer plan for the Overland Licensed Products and Allogene Overland PRC elects to continue the license for such Overland Licensed Products with increased milestones and royalties. Under the License Amendment terms such increased milestones and royalties consist of up to $115.0 million in milestone payments for each Overland Licensed Product and tiered mid single-digit to low double-digit royalties on net sales in the JV Territory. As part of the Organizational Restructuring, Allogene Overland was renamed Overland Therapeutics Inc. (Overland Therapeutics). Based on the License Agreement, promises that the Company concluded were distinct performance obligations 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

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 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 on 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 September 30, 2024 and December 31, 2023. The balance sheet classification of our lease liabilities were as follows (in thousands): September 30, 2024 December 31, 2023 Operating lease liabilities Current portion included in accrued and other current liabilities $ 7,389 $ 6,775 Long-term portion of lease liabilities 85,135 88,346 Total operating lease liabilities $ 92,525 $ 95,121 The components of lease costs for operating leases, which were recognized in operating expenses, were as follows (in thousands): Three Months Ended Nine Months Ended 2024 2023 2024 2023 Operating lease cost $ 2,900 $ 3,180 $ 8,931 $ 9,536 Variable lease cost 834 587 2,209 1,950 Total lease costs $ 3,734 $ 3,767 $ 11,140 $ 11,486 Cash paid for amounts included in the measurement of lease liabilities for the nine months ended September 30, 2024 was $9.3 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 September 30, 2024 were as follows: Year ending December 31: (In thousands) 2024 (remaining 3 months) $ 3,197 2025 12,920 2026 13,163 2027 13,612 2028 14,076 2029 and thereafter 65,386 Total undiscounted lease payments 122,354 Less: Present value adjustment (29,829) Total $ 92,525 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 6.25%. As of September 30, 2024, the weighted average remaining lease term for our operating leases is 8.35 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 September 30, 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 September 30, 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 September 30, 2024, the Company had non-cancellable purchase commitments of $2.3 million.

Equity Investments and Equity M

Equity Investments and Equity Method Investments	9 Months Ended
	Sep. 30, 2024
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments and Equity Method Investments	Equity Investments and 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. On May 17, 2024, Notch closed the Notch Series B Financing which caused the Company’s share in Notch to decrease to 13.0% immediately following this transaction. Accordingly, effective May 17, 2024, the Company started to account for its investment in Notch as an equity investment measured at cost less impairment. The Company’s total equity investment in Notch as of September 30, 2024 was $2.0 million. The Company’s total equity investment in Notch as of December 31, 2023 was $3.6 million and the Company accounted for the investment using the equity method of accounting. For the quarter to date and year to date periods through May 17, 2024, the Company recognized its share of Notch’s net loss of zero and $1.7 million, respectively, under the other income and expense, net caption within the condensed consolidated statements of operations. For the three and nine months ended September 30, 2023, the Company recognized its share of Notch’s net loss of $1.5 million and $4.5 million, respectively, under the other income and expense, net caption within the condensed consolidated statements of operations. During the three and nine months ended September 30, 2023, the Company recognized $3.0 million of impairment loss under the other expenses caption within the condensed consolidated statements of operations. No impairment loss was recorded in 2024. Overland Therapeutics, Inc. 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. Upon completion of the Organizational Restructuring, Overland’s ownership in Allogene Overland increased to 82% and the Company’s ownership decreased to 18%. As part of the Organizational Restructuring, Overland distributed all Series Seed Preferred Shares of Allogene Overland held by Overland to HBP and Allogene Overland was renamed to Overland Therapeutics. The Company’s total equity investment in Overland Therapeutics was zero as of September 30, 2024 and December 31, 2023, and the Company accounted for the investment using the equity method of accounting. For the three months ended September 30, 2024, the Company recognized its share of Overland Therapeutics' net loss of $1.1 million under the other income and expense, net caption within the condensed consolidated statements of operations. For the nine months ended September 30, 2024, the Company recognized its gain from the Organizational Restructuring of $1.1 million which was offset by its share of Overland Therapeutics' net loss of $1.1 million under the other income and expense, net caption within the condensed consolidated statement of operations. For the three and nine months ended September 30, 2023, the Company recognized its share of Overland Therapeutics’ net loss of $1.0 million and $3.4 million, respectively, under the other income and expense, net caption within the condensed consolidated statement of operations.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 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 September 30, 2024, there were 9,508,639 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 5,894,664 3.11 8.87 Options exercised (357,993) 2.27 $ 597 Options forfeited (3,394,248) 10.93 Balance, September 30, 2024 23,955,369 $ 8.22 7.75 $ 576 Exercisable, September 30, 2024 17,409,307 $ 9.75 7.32 $ 258 Vested and expected to vest, September 30, 2024 23,955,369 $ 8.22 7.75 $ 576 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 September 30, 2024. For the nine months ended September 30, 2024, the estimated weighted-average grant-date fair value of employee options granted was $2.07 per share. As of September 30, 2024, there was $41.7 million of unrecognized stock-based compensation related to unvested stock options, which is expected to be recognized over a weighted-average period of 2.0 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: Nine Months Ended September 30, 2024 2023 Expected term in years 5.02 - 6.12 5.27 - 6.08 Expected volatility 72.85% - 73.97% 73.18% - 73.85% Expected risk-free interest rate 3.42% - 4.32% 3.45% - 4.30% Expected dividend 0% 0% 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 5,091,392 4.09 1.37 Vested (1,796,660) 9.76 Forfeited (2,199,686) 7.92 Unvested September 30, 2024 13,275,517 $ 5.06 1.57 $ 37,171 Vested and expected to vest, September 30, 2024 13,275,517 $ 5.06 1.57 $ 37,171 As of September 30, 2024, there was $38.4 million of unrecognized stock-based compensation related to unvested restricted stock units, which is expected to be recognized over a weighted-average period of 2.2 years. As of September 30, 2024, the Company had 2,433,913 outstanding performance-based restricted stock units and 1,814,134 outstanding restricted stock units with a market condition granted to certain executive officers and other employees pursuant to the 2018 Plan, including 30,653 performance-based restricted stock units granted in the quarter ended September 30, 2024. These awards are subject to the holders’ continuous service to the Company through each applicable vesting event. Through September 30, 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 for the three and nine months ended September 30, 2024 and 2023. The Company recognized $0.7 million and $2.2 million in stock-based compensation expense related to the restricted stock units with a market condition for the three and nine months ended September 30, 2024, respectively. The Company recognized $0.5 million and $1.5 million in stock-based compensation expense related to the restricted stock units with market condition for the three and nine months ended September 30, 2023, respectively. Stock-based compensation expense For the three and nine months ended September 30, 2024, the Company recorded $13.4 million and $38.9 million, respectively, of stock-based compensation expense related to stock options, restricted stock units and employee stock purchase plans as research and development and general and administrative expense in its condensed consolidated statements of operations and comprehensive loss. For the three and nine months ended September 30, 2023, the Company recorded $15.4 million and $50.7 million, respectively, of stock-based compensation expense related to stock options, restricted stock units and employee stock purchase plans 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	9 Months Ended
	Sep. 30, 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 PRC. On May 24, 2024, the License Agreement was amended. During the three months ended September 30, 2024 and 2023, the Company recognized zero and less than $0.1 million of collaboration revenue under this arrangement, respectively. During the nine months ended September 30, 2024 and 2023, the Company recognized less than $0.1 million of collaboration revenue under this arrangement. For the three months ended September 30, 2024, the Company recognized its share of Overland Therapeutics' net loss of $1.1 million under the other income and expense, net caption within the condensed consolidated statements of operations. For the nine months ended September 30, 2024, the Company recognized its gain from the Organizational Restructuring of $1.1 million which was offset by its share of Overland Therapeutics' net loss of $1.1 million under the other income and expense, net caption within the condensed consolidated statement of operations. For the three and nine months ended September 30, 2023, the Company recognized its share of Overland Therapeutics’ net loss of $1.0 million and $3.4 million, respectively, under the other income and expense, net caption within the condensed consolidated statement of operations. 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 $2.3 million as of September 30, 2024. For the three and nine months ended September 30, 2024, the Company recorded $0.1 million and $0.3 million of rent expense related to this lease, respectively. 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 and $0.3 million for the three and nine months ended September 30, 2023, respectively. 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 and $0.6 million for the three and nine months ended September 30, 2024, respectively, and $0.3 million and $0.7 million for the three and nine months ended September 30, 2023, respectively.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 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	9 Months Ended
	Sep. 30, 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: September 30, 2024 2023 Stock options to purchase common stock 23,955,369 21,989,462 Restricted stock units subject to vesting 13,275,517 12,169,837 Expected shares to be purchased under Employee Stock Purchase Plan 1,140,573 1,289,434 Early exercised stock options subject to future vesting — 58,360 Total 38,371,459 35,507,093

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net loss	$ (66,293)	$ (66,358)	$ (65,000)	$ (62,287)	$ (79,232)	$ (99,968)	$ (197,651)	$ (241,487)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	9 Months Ended
	Sep. 30, 2024 shares	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Deborah Messemer [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		Type of Trading Arrangement Name and Position Action Adoption Rule 10b5-1* Non- Total Shares of Common Stock to be Sold Expiration Date Deborah Messemer, Director Adoption August 30, 2024 X ― 61,529 June 30, 2025 * Contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. ** “Non-Rule 10b5-1 trading arrangement” as defined in Item 408(c) of Regulation S-K under the Exchange Act.
Name	Deborah Messemer
Title	Director
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	August 30, 2024
Expiration Date	June 30, 2025
Arrangement Duration	304 days
Aggregate Available	61,529	61,529

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 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 September 30, 2024, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2024 and 2023, the condensed consolidated statements of stockholders’ equity as of September 30, 2024 and 2023, the condensed consolidated statements of cash flows for the nine months ended September 30, 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 and nine months ended September 30, 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, the CIRM award liability 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 and nine months ended September 30, 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, with exception of the following.
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 In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (ASU 2023-07), which requires all public entities, including public entities with a single reportable segment, to provide in interim and annual periods one or more measures of segment profit or loss used by the chief operating decision maker to allocate resources and assess performance. Additionally, the standard requires disclosures of significant segment expenses and other segment items as well as incremental qualitative disclosures. The guidance in this update is effective for fiscal years beginning after December 15, 2023, and interim periods after December 15, 2024. The Company is currently in the process of evaluating the effects of this pronouncement on its related disclosures. In December 2023, the FASB issued Accounting Standard Update No. 2023-09, Income taxes (Topic 740), Improvement to income tax disclosures , which enhances the disclosures required for income taxes in the Company’s annual financial statements. This standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company does not plan to adopt this standard early. The adoption of this standard is not expected to have a material impact on the Company’s financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2024 and as of December 31, 2023 are presented in the following tables: September 30, 2024 Level 1 Level 2 Level 3 Fair Value (In thousands) Financial Assets: Money market funds (1) $ 43,977 $ — $ — $ 43,977 Commercial paper — 36,840 — 36,840 Corporate bonds — 125,587 — 125,587 U.S. treasury securities 107,226 — — 107,226 U.S. agency securities — 72,813 — 72,813 Asset-backed securities — 9,680 — 9,680 Total financial assets $ 151,203 $ 244,920 $ — $ 396,123 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)	9 Months Ended
	Sep. 30, 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 September 30, 2024 and as of December 31, 2023 are presented in the following tables: September 30, 2024 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) Money market funds $ 43,977 $ — $ — $ 43,977 Commercial paper 36,818 35 (13) 36,840 Corporate bonds 125,371 218 (2) 125,587 U.S. treasury securities 107,072 157 (3) 107,226 U.S. agency securities 72,617 196 — 72,813 Asset-backed securities 9,669 11 — 9,680 Total cash equivalents and investments $ 395,524 $ 617 $ (18) $ 396,123 Classified as: Cash equivalents $ 43,977 Short-term investments 240,325 Long-term investments 111,821 Total cash equivalents and investments $ 396,123 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)	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Property and Equipment	Property and Equipment consist of the following: September 30, December 31, (In thousands) Leasehold improvements 107,545 108,621 Laboratory equipment 32,089 33,157 Computer equipment and purchased software 4,752 4,663 Furniture and fixtures 4,171 4,121 Total 148,557 150,562 Less: accumulated depreciation (59,568) (51,084) Total property and equipment, net $ 88,989 $ 99,478

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Schedule of Lease Liabilities	The balance sheet classification of our lease liabilities were as follows (in thousands): September 30, 2024 December 31, 2023 Operating lease liabilities Current portion included in accrued and other current liabilities $ 7,389 $ 6,775 Long-term portion of lease liabilities 85,135 88,346 Total operating lease liabilities $ 92,525 $ 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 Nine Months Ended 2024 2023 2024 2023 Operating lease cost $ 2,900 $ 3,180 $ 8,931 $ 9,536 Variable lease cost 834 587 2,209 1,950 Total lease costs $ 3,734 $ 3,767 $ 11,140 $ 11,486
Summary of Future Lease Payments Under Lease Liability	The undiscounted future non-cancellable lease payments under the Company's operating leases as of September 30, 2024 were as follows: Year ending December 31: (In thousands) 2024 (remaining 3 months) $ 3,197 2025 12,920 2026 13,163 2027 13,612 2028 14,076 2029 and thereafter 65,386 Total undiscounted lease payments 122,354 Less: Present value adjustment (29,829) Total $ 92,525

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 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 5,894,664 3.11 8.87 Options exercised (357,993) 2.27 $ 597 Options forfeited (3,394,248) 10.93 Balance, September 30, 2024 23,955,369 $ 8.22 7.75 $ 576 Exercisable, September 30, 2024 17,409,307 $ 9.75 7.32 $ 258 Vested and expected to vest, September 30, 2024 23,955,369 $ 8.22 7.75 $ 576
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: Nine Months Ended September 30, 2024 2023 Expected term in years 5.02 - 6.12 5.27 - 6.08 Expected volatility 72.85% - 73.97% 73.18% - 73.85% Expected risk-free interest rate 3.42% - 4.32% 3.45% - 4.30% 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 5,091,392 4.09 1.37 Vested (1,796,660) 9.76 Forfeited (2,199,686) 7.92 Unvested September 30, 2024 13,275,517 $ 5.06 1.57 $ 37,171 Vested and expected to vest, September 30, 2024 13,275,517 $ 5.06 1.57 $ 37,171

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 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: September 30, 2024 2023 Stock options to purchase common stock 23,955,369 21,989,462 Restricted stock units subject to vesting 13,275,517 12,169,837 Expected shares to be purchased under Employee Stock Purchase Plan 1,140,573 1,289,434 Early exercised stock options subject to future vesting — 58,360 Total 38,371,459 35,507,093

Description of Business (Detail

Description of Business (Details) - USD ($) $ / shares in Units, $ in Thousands	May 13, 2024	Sep. 30, 2024	Dec. 31, 2023
Subsidiary, Sale of Stock [Line Items]
Cash and cash equivalents and marketable securities		$ 403,400
Accumulated deficit		$ 1,759,884	$ 1,562,233
Registered Offering
Subsidiary, Sale of Stock [Line Items]
Shares sold in transaction (in shares)	37,931,035
Purchase price (in dollars per share)	$ 2.90
Gross proceeds from sale of stock	$ 110,000
Issuance costs	$ 4,700
Registered Offering | Directors And Executive Officers
Subsidiary, Sale of Stock [Line Items]
Shares sold in transaction (in shares)	1,034,484

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - Fair Value, Measurements, Recurring - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 396,123,000	$ 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 ($)	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 396,123,000	$ 444,078,000
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	43,977,000	78,536,000
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	36,840,000
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	125,587,000	97,166,000
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	107,226,000	229,516,000
U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	72,813,000	38,860,000
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	9,680,000
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	151,203,000	308,052,000
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	43,977,000	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	107,226,000	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 1 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	244,920,000	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	36,840,000
Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	125,587,000	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	72,813,000	38,860,000
Level 2 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	9,680,000
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
Level 3 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 0

Financial Instruments - Cash Eq

Financial Instruments - Cash Equivalents, Restricted Cash and Investments, Classified as Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 395,524	$ 444,589
Unrealized Gains	617	245
Unrealized Losses	(18)	(756)
Cash equivalents	43,977	78,536
Short-term investments	240,325	365,542
Long-term investments	111,821	0
Total cash equivalents and investments	396,123	444,078
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	43,977	78,536
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	43,977	78,536
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	36,818
Unrealized Gains	35
Unrealized Losses	(13)
Fair Value	36,840
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	125,371	97,265
Unrealized Gains	218	113
Unrealized Losses	(2)	(212)
Fair Value	125,587	97,166
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	107,072	229,563
Unrealized Gains	157	132
Unrealized Losses	(3)	(179)
Fair Value	107,226	229,516
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	72,617	39,225
Unrealized Gains	196	0
Unrealized Losses	0	(365)
Fair Value	72,813	$ 38,860
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,669
Unrealized Gains	11
Unrealized Losses	0
Fair Value	$ 9,680

Financial Instruments - Additio

Financial Instruments - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Investments, All Other Investments [Abstract]
Maximum remaining contractual maturities of available-for-sale securities (in years)	3 years		3 years
Realized losses on available-for-sale securities	$ 0	$ 0	$ 0	$ 1
Net unrealized loss position	0		0		$ 48.4
Accrued interest receivable from available-fore-sale investments	$ 2.8		$ 2.8		$ 1.7

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 148,557	$ 150,562
Less: accumulated depreciation	(59,568)	(51,084)
Total property and equipment, net	88,989	99,478
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	107,545	108,621
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	32,089	33,157
Computer equipment and purchased software
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	4,752	4,663
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 4,171	$ 4,121

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) $ in Thousands			1 Months Ended		3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Apr. 26, 2024 USD ($)	Jan. 04, 2024	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($) property	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Restructuring Cost and Reserve [Line Items]
Operating lease right-of-use asset			$ 46,313		$ 46,313			$ 46,313		$ 63,703
Impairment of long-lived assets					10,728	$ 0		15,717	$ 0
Proceeds from CIRM award								2,280	0
Interest expense					100	$ 0		100	$ 0
California Institute For Regenerative Medicine (CIRM)
Restructuring Cost and Reserve [Line Items]
Grant award, amount	$ 15,000
Grant award, grantee maximum expected contribution	$ 25,900
Grant award, royalty fee, amount due to other party, multiplier	9
Grant award, loan conversion period deadline, anniversary of award	10 years
Basis spread on variable rate	10%
Proceeds from CIRM award								2,300
Interest expense					100			100
Accrued interest			100		100			100
California Institute For Regenerative Medicine (CIRM) | Minimum
Restructuring Cost and Reserve [Line Items]
Grant award, amount converted to loan, repayment percentage	0.80
California Institute For Regenerative Medicine (CIRM) | Maximum
Restructuring Cost and Reserve [Line Items]
Grant award, amount converted to loan, repayment percentage	1
Reduction To Workforce
Restructuring Cost and Reserve [Line Items]
Positions eliminated, percent		22%
Payments for restructuring								2,900
Restructuring reserve			200		200			200
South San Francisco Building One
Restructuring Cost and Reserve [Line Items]
Number of properties to be subleased | property				1
Operating lease, right-of-use asset, fair value disclosure			1,200	$ 2,500	1,200		$ 2,500	1,200
Operating lease right-of-use asset			$ 2,400	7,500	2,400		7,500	2,400
Impairment of long-lived assets				$ 5,000	1,200			$ 6,200
Sublease income					$ 1,900		$ 4,000
South San Francisco Building One | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow
Restructuring Cost and Reserve [Line Items]
Operating lease, right of use asset, measurement input			0.095	0.090	0.095		0.090	0.095
South San Francisco Building Two
Restructuring Cost and Reserve [Line Items]
Operating lease, right-of-use asset, fair value disclosure			$ 3,100		$ 3,100			$ 3,100
Operating lease right-of-use asset			12,600		12,600			12,600
Impairment of long-lived assets					$ 9,500			$ 9,500		13,200
Sublease income			$ 4,700							$ 22,700
South San Francisco Building Two | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow
Restructuring Cost and Reserve [Line Items]
Operating lease, right of use asset, measurement input										0.090

License and Collaboration Agr_2

License and Collaboration Agreements - Pfizer (Details) - Pfizer - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 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	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		9 Months Ended
	Sep. 30, 2024 USD ($) country product	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) country product	Sep. 30, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development	$ 44,713,000	$ 45,977,000	$ 147,327,000	$ 188,253,000
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	$ 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		1
Number of countries to commercialize product | country	1		1

License and Collaboration Agr_4

License and Collaboration Agreements - Servier (Details) $ in Thousands, € in Millions		3 Months Ended		9 Months Ended
	May 10, 2024 EUR (€)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 EUR (€)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development | $		$ 44,713	$ 45,977	$ 147,327	$ 188,253
License and Collaboration Agreement | Servier
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development cost payable by collaboration partner (in percent)	40%
License and Collaboration Agreement | Servier | UNITED STATES
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty rate, percent	10%
Reduction to royalty rate, percent	10%
License and Collaboration Agreement | Servier | Regulatory Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate milestone payments	€ 75
Aggregate potential milestone payments, remaining obligation	60
Milestone payable per indication	55
Milestone payable remaining | $		50,000		50,000
Aggregate potential milestone payable	20					€ 20
Research and development | $		$ 0	$ 100	$ 5,400	$ 400
License and Collaboration Agreement | Servier | Sales Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate milestone payments	€ 80
Servier | License and Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development costs payable by the Company (in percent)				60%

License and Collaboration Agr_5

License and Collaboration Agreements - Notch Therapeutics (Details)		1 Months Ended		3 Months Ended		9 Months Ended
	Nov. 01, 2019 USD ($)	Oct. 31, 2021 USD ($)	Feb. 28, 2021 USD ($)	Sep. 30, 2024 USD ($) target	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) target	Sep. 30, 2023 USD ($)	May 17, 2024	Jan. 25, 2024 USD ($)	Dec. 31, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investments				$ 0		$ 0				$ 3,645,000
Impairment of equity method investment						0	$ 3,000,000
Research and development				44,713,000	$ 45,977,000	147,327,000	188,253,000
Notch Therapeutics, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investments	$ 5,000,000			2,000,000		2,000,000				$ 3,600,000
Ownership percentage	25%
Payments for additional investment in interest		$ 1,800,000	$ 15,900,000
Impairment of equity method investment					3,000,000	$ 0	3,000,000
Notch Therapeutics, Inc. | Voting Interest
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage		23%	20.70%					13%
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	0	$ 0	1,800,000
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		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	$ 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		0

License and Collaboration Agr_6

License and Collaboration Agreements - MD Anderson Cancer Center (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 06, 2020	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2020
Research and Development Expense | University Of Texas M D Anderson Cancer Center
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration costs			$ 0.2		$ 1.2
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, advance 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		$ 0.8		$ 1.1

License and Collaboration Agr_7

License and Collaboration Agreements - Overland Therapeutics, Inc. (Details) - USD ($)			3 Months Ended		9 Months Ended
	May 24, 2024	Dec. 14, 2020	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration revenue - related party			$ 0	$ 22,000	$ 22,000	$ 74,000
Allogene Overland
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum ownership threshold, percent	0.075
Allogene Overland, Allogene Overland BioPharm (HK) Limited
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration revenue - related party			0	100,000	100,000	100,000
Allogene Overland | Other Noncurrent Liabilities
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred revenue			4,600,000		4,600,000
Allogene Overland | License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Remaining performance obligation	$ 4,600,000
Allogene Overland | License | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Remaining performance obligation, variable consideration	115,000,000
Allogene Overland | Manufacturing License, Know-How
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Remaining performance obligation	1,900,000
Allogene Overland | Know-How Developed In Future Periods
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Remaining performance obligation	$ 2,700,000
Overland Therapeutics (Formerly Known As Allogene Overland)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration revenue - related party			100,000	$ 100,000	100,000	$ 100,000
Allogene Overland | Overland US
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Subsidiary, ownership percentage, parent	100%
Allogene Overland
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage		49%
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%
Overland Therapeutics (Formerly Known As Allogene Overland)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investment, gain on restructuring	$ 1,100,000
Equity method investments			$ 0		$ 0		$ 0
Overland Therapeutics (Formerly Known As Allogene Overland) | Voting Interest
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership percentage			20%		20%

License and Collaboration Agr_8

License and Collaboration Agreements - Antion (Details) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 05, 2022 USD ($) product	Jul. 31, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment for investment in stock					$ 314,501	$ 369,927
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	$ 0	0	$ 1,800
Antion Collaboration Agreement | Other Noncurrent Assets
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity investment, total			$ 0		$ 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		9 Months Ended
	Jan. 03, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development		$ 44,713	$ 45,977	$ 147,327	$ 188,253
Foresight Diagnostics Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Committed funding	$ 26,200
Research and development		$ 500		$ 2,700

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended				9 Months Ended
	Feb. 28, 2023 ft²	Jul. 31, 2022 ft²	Feb. 28, 2019 ft² renewal	Dec. 31, 2018 ft²	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2021 ft²	Dec. 31, 2020 USD ($)	Jul. 31, 2020 USD ($)	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					$ 9.3
Weighted average discount rate (as a percent)					6.25%
Weighted average remaining lease term (in years)					8 years 4 months 6 days
Agreement term									20 years
Termination payment									$ 4.3
Non-cancellable purchase commitments					$ 2.3
Bellco | Sublease Agreement | Related Party
Operating Leased Assets [Line Items]
Area of office space (in square feet) | ft²	2,218	737		1,293
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	Sep. 30, 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	$ 7,389	$ 6,775
Long-term portion of lease liabilities	85,135	88,346
Total operating lease liabilities	$ 92,525	$ 95,121

Commitments and Contingencies_3

Commitments and Contingencies - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 2,900	$ 3,180	$ 8,931	$ 9,536
Variable lease cost	834	587	2,209	1,950
Total lease costs	$ 3,734	$ 3,767	$ 11,140	$ 11,486

Commitments and Contingencies_4

Commitments and Contingencies - Undiscounted Future Lease Payments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
2024 (remaining 3 months)	$ 3,197
2025	12,920
2026	13,163
2027	13,612
2028	14,076
2029	65,386
Total undiscounted lease payments	122,354
Less: Present value adjustment	(29,829)
Total	$ 92,525	$ 95,121

Equity Investments and Equity_2

Equity Investments and Equity Method Investments (Details) - USD ($)		1 Months Ended		2 Months Ended	3 Months Ended		5 Months Ended	9 Months Ended
	Nov. 01, 2019	Oct. 31, 2021	Feb. 28, 2021	May 17, 2024	Sep. 30, 2024	Sep. 30, 2023	May 17, 2024	Sep. 30, 2024	Sep. 30, 2023	May 24, 2024	Dec. 31, 2023	Dec. 14, 2020
Schedule of Equity Method Investments [Line Items]
Equity method investments					$ 0			$ 0			$ 3,645,000
Impairment of equity method investment								0	$ 3,000,000
Overland Therapeutics (Formerly Known As Allogene Overland)
Schedule of Equity Method Investments [Line Items]
Subsidiary, ownership percentage, noncontrolling owner										18%
Overland Therapeutics (Formerly Known As Allogene Overland) | Overland Pharmaceuticals Inc.
Schedule of Equity Method Investments [Line Items]
Subsidiary, ownership percentage, parent										82%
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				2,000,000			2,000,000			3,600,000
Share of loss from equity method investments				$ 0		$ 1,500,000	$ 1,700,000		4,500,000
Impairment of equity method investment						3,000,000		0	3,000,000
Notch Therapeutics, Inc. | Voting Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage		23%	20.70%	13%			13%
Allogene Overland
Schedule of Equity Method Investments [Line Items]
Ownership percentage												49%
Share of loss from equity method investments					1,100,000	$ 1,000,000		1,100,000	$ 3,400,000
Carrying value					$ 0			0			$ 0
Share of gain from equity method investments, organizational restructuring								$ 1,100,000
Allogene Overland | Overland Pharmaceuticals Inc.
Schedule of Equity Method Investments [Line Items]
Ownership percentage												51%

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Jul. 19, 2022 USD ($) $ / shares shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 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)		9,508,639		9,508,639
Plan modification, incremental cost | $	$ 5.2
Stock-based compensation | $		$ 13.4	$ 15.4	$ 38.9	$ 50.7
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)				4 years
Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)				4 years
Unrecognized stock based compensation expense | $		$ 38.4		$ 38.4
Unrecognized stock based compensation expense, weighted average recognition period (in years)				2 years 2 months 12 days
Restricted stock units outstanding (in shares)		13,275,517		13,275,517		12,180,471
Restricted stock units, granted (in shares)				5,091,392
Stock options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	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 per share) | $ / shares	$ 13.31
Expiration period (in years)	7 years
Grants in period, weighted average grant date fair value (in dollars per share) | $ / shares				$ 2.07
Unrecognized stock based compensation expense | $		$ 41.7		$ 41.7
Unrecognized stock based compensation expense, weighted average recognition period (in years)				2 years
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 outstanding (in shares)		2,433,913		2,433,913
Restricted stock units, granted (in shares)		30,653
Stock-based compensation | $		$ 0	0	$ 0	0
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 outstanding (in shares)		1,814,134		1,814,134
Stock-based compensation | $		$ 0.7	$ 0.5	$ 2.2	$ 1.5
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option grant period (in years)				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 $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares
Number of Options
Number of options, beginning balance (in shares) | shares	21,812,946
Number of options, options granted (in shares) | shares	5,894,664
Number of options, options exercised (in shares) | shares	(357,993)
Number of options, options forfeited (in shares) | shares	(3,394,248)
Number of options, ending balance (in shares) | shares	23,955,369	21,812,946
Number of options, exercisable (in shares) | shares	17,409,307
Number of options, vested and expected to vest (in shares) | shares	23,955,369
Weighted- Average Exercise Price
Weighted-average exercise price, beginning balance (in dollars per share) | $ / shares	$ 9.93
Weighted-average exercise price, options granted (in dollars per share) | $ / shares	3.11
Weighted-average exercise price, options exercised (in dollars per share) | $ / shares	2.27
Weighted-average exercise price, options forfeited (in dollars per share) | $ / shares	10.93
Weighted-average exercise price, ending balance (in dollars per share) | $ / shares	8.22	$ 9.93
Weighted-average exercise price, exercisable (in dollars per share) | $ / shares	9.75
Weighted-average exercise price, vested and expected to vest (in dollars per share) | $ / shares	$ 8.22
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value, balance | $	$ 576	$ 662
Aggregate intrinsic value, exercised | $	597
Aggregate intrinsic value, exercisable | $	258
Aggregate intrinsic value, vested and expected to vest | $	$ 576
Weighted-Average Remaining Contract Term [Abstract]
Weighted-average remaining contract term, outstanding (in years)	7 years 9 months	7 years 6 months 10 days
Weighted-average remaining contract term, granted (in years)	8 years 10 months 13 days
Weighted-average remaining contract term, exercisable (in years)	7 years 3 months 25 days
Weighted-average remaining contract term, vested and expected to vest (in years)	7 years 9 months

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions (Details) - 2018 Plan	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	72.85%	73.18%
Expected volatility, maximum	73.97%	73.85%
Expected risk-free interest rate, minimum	3.42%	3.45%
Expected risk-free interest rate, maximum	4.32%	4.30%
Expected dividend	0%	0%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	5 years 7 days	5 years 3 months 7 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term in years	6 years 1 month 13 days	6 years 29 days

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Unit $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares
Restricted Stock Units
Restricted stock units, unvested, beginning balance (in shares) | shares	12,180,471
Restricted stock units, granted (in shares) | shares	5,091,392
Restricted stock units, vested (in shares) | shares	(1,796,660)
Restricted stock units, forfeited (in shares) | shares	(2,199,686)
Restricted stock units, unvested, ending balance (in shares) | shares	13,275,517	12,180,471
Restricted stock units, vested and expected to vest (in shares) | shares	13,275,517
Weighted- Average Grant Date Fair Value per Share
Weighted-average fair value at date of grant per share, beginning balance (in dollars per share) | $ / shares	$ 6.68
Weighted-average fair value at date of grant per share, granted (in dollars per share) | $ / shares	4.09
Weighted-average fair value at date of grant per share, vested (in dollars per share) | $ / shares	9.76
Weighted-average fair value at date of grant per share, forfeited (in dollars per share) | $ / shares	7.92
Weighted-average fair value at date of grant per share, ending balance (in dollars per share) | $ / shares	5.06	$ 6.68
Weighted-average fair value at date of grant per share, vested and expected to vest (in dollars per share) | $ / shares	$ 5.06
Weighted Average Remaining Vested Life [Abstract]
Weighted average remaining vesting life, unvested (in years)	1 year 6 months 25 days	2 years
Weighted average remaining vesting life, granted (in years)	1 year 4 months 13 days
Weighted average remaining vesting life, vested and expected to vest (in years)	1 year 6 months 25 days
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value, unvested | $	$ 37,171	$ 39,099
Aggregate intrinsic value, vested and expected to vest | $	$ 37,171

Related Party Transactions (Det

Related Party Transactions (Details)	1 Months Ended				3 Months Ended		9 Months Ended
	Feb. 28, 2023 ft²	Jul. 31, 2022 ft²	Dec. 31, 2018 ft²	Aug. 31, 2018 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Related Party Transaction [Line Items]
Collaboration revenue - related party					$ 0	$ 22,000	$ 22,000	$ 74,000
Operating lease right-of-use asset					46,313,000		46,313,000		$ 63,703,000
Operating lease liability					92,525,000		92,525,000		$ 95,121,000
Allogene Overland, Allogene Overland BioPharm (HK) Limited
Related Party Transaction [Line Items]
Collaboration revenue - related party					0	100,000	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					2,300,000		2,300,000
Operating lease liability					2,300,000		2,300,000
Non-cash rent expense					100,000		300,000
Bellco | Consulting Agreements | Related Party
Related Party Transaction [Line Items]
Cost of revenue					$ 200,000	300,000	$ 600,000	700,000
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		$ 300,000

Net Loss Per Share (Details)

Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 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)	38,371,459	35,507,093
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)	23,955,369	21,989,462
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)	13,275,517	12,169,837
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)	1,140,573	1,289,434
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	58,360