Atara Biotherapeutics (ATRA) 10-Q 1 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Oct. 27, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Registrant Name	ATARA BIOTHERAPEUTICS, INC.
Entity Central Index Key	0001604464
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity File Number	001-36548
Entity Tax Identification Number	46-0920988
Entity Address, Address Line One	2380 Conejo Spectrum Street
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Thousand Oaks
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	91320
City Area Code	805
Local Phone Number	623-4211
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	ATRA
Security Exchange Name	NASDAQ
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		101,922,250

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 64,791	$ 92,942
Short-term investments	37,617	149,877
Restricted cash	146	146
Accounts receivable	163	40,221
Inventories	6,591	1,586
Other current assets	9,388	10,308
Total current assets	118,696	295,080
Property and equipment, net	4,628	6,300
Operating lease assets	59,175	68,022
Other assets	6,289	7,018
Total assets	188,788	376,420
Current liabilities:
Accounts payable	6,511	6,871
Accrued compensation	14,430	17,659
Accrued research and development expenses	23,968	24,992
Deferred revenue	11,611	8,000
Other current liabilities	22,569	21,394
Total current liabilities	79,089	78,916
Deferred revenue - long-term	73,929	77,000
Operating lease liabilities - long-term	48,508	58,064
Liability related to the sale of future revenues - long-term	33,252	30,236
Other long-term liabilities	4,848	5,564
Total liabilities	239,626	249,780
Commitments and contingencies (Note 8)
Stockholders' equity (deficit):
Common stock - $0.0001 par value, 500,000 shares authorized as of September 30, 2023 and December 31, 2022; 101,922 and 95,927 shares issued and outstanding as of September 30, 2023 and December 31, 2022, respectively	10	10
Additional paid-in capital	1,858,423	1,821,721
Accumulated other comprehensive (loss) income	(571)	(2,067)
Accumulated deficit	(1,908,700)	(1,693,024)
Total stockholders' equity (deficit)	(50,838)	126,640
Total liabilities and stockholders' equity (deficit)	$ 188,788	$ 376,420

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	101,922,000	95,927,000
Common stock, shares outstanding	101,922,000	95,927,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Commercialization revenue	$ 2,020	$ 0	$ 3,697	$ 0
License and collaboration revenue	118	4,459	624	63,352
Total revenue	2,138	4,459	4,321	63,352
Costs and operating expenses:
Cost of commercialization revenue	2,615	0	5,726	0
Research and development expenses	56,888	70,157	175,185	210,018
General and administrative expenses	12,247	18,924	39,454	58,308
Total costs and operating expenses	71,750	89,081	220,365	268,326
Loss from operations	(69,612)	(84,622)	(216,044)	(204,974)
Other income (expense), net:
Interest income	1,218	973	4,715	1,904
Interest expense	(1,395)	(123)	(4,109)	(256)
Gain on sale of ATOM Facility	0	0	0	50,237
Other income (expense), net	(27)	(309)	(234)	(631)
Total other income (expense), net	204	541	372	51,254
Loss before provision for (benefit from) income taxes	(69,816)	(84,081)	(215,672)	(153,720)
Provision for (benefit from) income taxes	(19)	10	4	10
Net loss	(69,797)	(84,091)	(215,676)	(153,730)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	362	(341)	1,496	(2,591)
Comprehensive loss	$ (69,435)	$ (84,432)	$ (214,180)	$ (156,321)
Basic loss per common share	$ (0.66)	$ (0.82)	$ (2.05)	$ (1.51)
Diluted loss per common share	$ (0.66)	$ (0.82)	$ (2.05)	$ (1.51)
Basic weighted-average shares outstanding	106,401	102,423	105,163	101,590
Diluted weighted-average shares outstanding	106,401	102,423	105,163	101,590

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Common Stock At The Market Offering	Additional Paid-in Capital	Additional Paid-in Capital At The Market Offering	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance at Dec. 31, 2021	$ 279,614	$ 9		$ 1,744,695		$ (368)	$ (1,464,722)
Beginning balance (in shares) at Dec. 31, 2021		91,671
Issuance of common stock, net of commissions and offering costs, value	20,516				$ 20,516
Issuance of common stock, net of commissions and offering costs, shares			1,320
RSU settlements, net of shares withheld	(616)			(616)
RSU settlements, net of shares withheld, shares		405
Issuance of common stock pursuant to employee stock awards	96			96
Issuance of common stock pursuant to employee stock awards, shares		10
Stock-based compensation expense	14,335			14,335
Net (loss) income	(88,105)						(88,105)
Unrealized gain (loss) on available-for-sale securities	(1,524)					(1,524)
Ending balance at Mar. 31, 2022	224,316	$ 9		1,779,026		(1,892)	(1,552,827)
Ending balance (in shares) at Mar. 31, 2022		93,406
Beginning balance at Dec. 31, 2021	279,614	$ 9		1,744,695		(368)	(1,464,722)
Beginning balance (in shares) at Dec. 31, 2021		91,671
Net (loss) income	(153,730)
Unrealized gain (loss) on available-for-sale securities	(2,591)
Ending balance at Sep. 30, 2022	187,113	$ 9		1,808,515		(2,959)	(1,618,452)
Ending balance (in shares) at Sep. 30, 2022		94,879
Beginning balance at Mar. 31, 2022	224,316	$ 9		1,779,026		(1,892)	(1,552,827)
Beginning balance (in shares) at Mar. 31, 2022		93,406
RSU settlements, net of shares withheld	(3)			(3)
RSU settlements, net of shares withheld, shares		647
Issuance of common stock pursuant to employee stock awards	1,309			1,309
Issuance of common stock pursuant to employee stock awards, shares		303
Stock-based compensation expense	14,117			14,117
Net (loss) income	18,466						18,466
Unrealized gain (loss) on available-for-sale securities	(726)					(726)
Ending balance at Jun. 30, 2022	257,479	$ 9		1,794,449		(2,618)	(1,534,361)
Ending balance (in shares) at Jun. 30, 2022		94,356
RSU settlements, net of shares withheld	(4)			(4)
RSU settlements, net of shares withheld, shares		517
Issuance of common stock pursuant to employee stock awards	47			47
Issuance of common stock pursuant to employee stock awards, shares		6
Stock-based compensation expense	14,023			14,023
Net (loss) income	(84,091)						(84,091)
Unrealized gain (loss) on available-for-sale securities	(341)					(341)
Ending balance at Sep. 30, 2022	187,113	$ 9		1,808,515		(2,959)	(1,618,452)
Ending balance (in shares) at Sep. 30, 2022		94,879
Beginning balance at Dec. 31, 2022	126,640	$ 10		1,821,721		(2,067)	(1,693,024)
Beginning balance (in shares) at Dec. 31, 2022		95,927
Issuance of common stock, net of commissions and offering costs, value	590				$ 590
Issuance of common stock, net of commissions and offering costs, shares			148
RSU settlements, net of shares withheld	(93)			(93)
RSU settlements, net of shares withheld, shares		463
Stock-based compensation expense	11,764			11,764
Net (loss) income	(74,771)						(74,771)
Unrealized gain (loss) on available-for-sale securities	830					830
Ending balance at Mar. 31, 2023	64,960	$ 10		1,833,982		(1,237)	(1,767,795)
Ending balance (in shares) at Mar. 31, 2023		96,538
Beginning balance at Dec. 31, 2022	126,640	$ 10		1,821,721		(2,067)	(1,693,024)
Beginning balance (in shares) at Dec. 31, 2022		95,927
Net (loss) income	(215,676)
Unrealized gain (loss) on available-for-sale securities	1,496
Ending balance at Sep. 30, 2023	(50,838)	$ 10		1,858,423		(571)	(1,908,700)
Ending balance (in shares) at Sep. 30, 2023		101,922
Beginning balance at Mar. 31, 2023	64,960	$ 10		1,833,982		(1,237)	(1,767,795)
Beginning balance (in shares) at Mar. 31, 2023		96,538
Exercise of pre-funded warrants		2,916
RSU settlements, net of shares withheld	(1)			(1)
RSU settlements, net of shares withheld, shares		1,074
Issuance of common stock pursuant to employee stock awards	747			747
Issuance of common stock pursuant to employee stock awards, shares		574
Stock-based compensation expense	12,552			12,552
Net (loss) income	(71,108)						(71,108)
Unrealized gain (loss) on available-for-sale securities	304					304
Ending balance at Jun. 30, 2023	7,454	$ 10		1,847,280		(933)	(1,838,903)
Ending balance (in shares) at Jun. 30, 2023		101,102
RSU settlements, net of shares withheld, shares		820
Stock-based compensation expense	11,143			11,143
Net (loss) income	(69,797)						(69,797)
Unrealized gain (loss) on available-for-sale securities	362					362
Ending balance at Sep. 30, 2023	$ (50,838)	$ 10		$ 1,858,423		$ (571)	$ (1,908,700)
Ending balance (in shares) at Sep. 30, 2023		101,922

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
At The Market Offering | Common Stock
Stock issuance, discounts, commissions and offering costs	$ 97	$ 419

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities
Net loss	$ (215,676)	$ (153,730)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on sale of ATOM Facility	0	(50,237)
Stock-based compensation expense	35,459	42,475
Depreciation and amortization expense	3,624	4,398
Accretion of liability related to sale of future revenues	3,729	0
Amortization (accretion) of investment premiums (discounts)	(1,320)	974
Non-cash operating lease expense	8,847	6,103
Other non-cash items, net	148	70
Changes in operating assets and liabilities:
Accounts receivable	40,058	737
Inventories	(5,005)	0
Other current assets	920	(3,903)
Other assets	(119)	(139)
Accounts payable	(319)	(4,760)
Accrued compensation	(3,229)	(7,545)
Accrued research and development expenses	(1,024)	4,417
Other current liabilities	607	5,595
Deferred revenue	540	(51,468)
Operating lease liabilities	(9,953)	(6,781)
Other long-term liabilities	142	244
Net cash used in operating activities	(142,571)	(213,550)
Investing activities
Purchases of short-term investments	(83,647)	(181,164)
Proceeds from maturities and sales of short-term investments	198,723	242,293
Purchases of property and equipment	(1,179)	(4,156)
Proceeds from sale of property and equipment	25	0
Net proceeds from sale of ATOM Facility	0	94,765
Net cash (used in) provided by investing activities	113,922	151,738
Financing activities
Proceeds from issuance of common stock through ATM facilities, net	590	20,516
Proceeds from employee stock awards	747	1,452
Taxes paid related to net share settlement of restricted stock units	(94)	(623)
Principal payments on finance lease obligations	(732)	(396)
Other financing activities, net	(13)	(155)
Net cash provided by financing activities	498	20,794
Decrease in cash, cash equivalents and restricted cash	(28,151)	(41,018)
Cash, cash equivalents and restricted cash at beginning of period	93,088	107,478
Cash, cash equivalents and restricted cash at end of period	64,937	66,460
Non-cash investing and financing activities
Property and equipment purchases included in accounts payable and other accrued liabilities	20	35
Supplemental cash flow disclosure
Cash paid for interest	332	256
Cash paid for income taxes	$ 2	$ 19

Description of Business

Description of Business	9 Months Ended
	Sep. 30, 2023
Description Of Business [Abstract]
Description of Business	1. Description of Business Atara Biotherapeutics, Inc. (Atara, we, our or the Company) was incorporated in August 2012 in Delaware . Atara is a leader in T-cell immunotherapy, leveraging its novel allogeneic Epstein-Barr Virus (EBV) T-cell platform to develop transformative therapies for patients with cancer and autoimmune disease. We have several T-cell immunotherapies in clinical development and are progressing multiple next-generation allogeneic chimeric antigen receptor T-cell (CAR T) programs. Our most advanced T-cell immunotherapy program, tab-cel ® (tabelecleucel), has received marketing authorization approval under the proprietary name Ebvallo™ by the European Commission (EC) for commercial sale and use in the European Union (EU) and by the Medicines and Healthcare products Regulatory Agency (MHRA) for commercial sale and use in the United Kingdom (UK). Tab-cel is currently in Phase 3 development in the US. In October 2021, we entered into a commercialization agreement (Pierre Fabre Commercialization Agreement) with Pierre Fabre Medicament (Pierre Fabre), as amended in September 2022, pursuant to which we granted to Pierre Fabre an exclusive, field-limited license to commercialize and distribute Ebvallo in Europe and select emerging markets in the Middle East, Africa, Eastern Europe and Central Asia (the Initial Territory), following regulatory approval. See Note 5 for further information. In December 2022, we sold a portion of our right to receive royalties and certain milestones in Ebvallo under the Pierre Fabre Commercialization Agreement to HCR Molag Fund L.P. (HCRx) for a total investment amount of $ 31.0 million, subject to a repayment cap between 185 % and 250 % of the total investment amount by HCRx. See Note 6 for further information. In October 2023, we amended and restated the Pierre Fabre Commercialization Agreement. See Note 11 for further information. We have licensed rights to T-cell product candidates from Memorial Sloan Kettering Cancer Center (MSK), rights related to our next-generation CAR T programs from MSK, and rights to know-how and technology from the Council of the Queensland Institute of Medical Research (QIMR Berghofer). See Note 8 for further information. In January 2022, we entered into an asset purchase agreement with FUJIFILM Diosynth Biotechnologies California, Inc. (FDB) and, for certain limited purposes, FUJIFILM Holdings America Corporation, to sell all of the Company’s right, title and interest in and to certain assets related to the Atara T-Cell Operations and Manufacturing facility (ATOM Facility) located in Thousand Oaks, California for $ 100 million in cash, subject to potential post-closing adjustments pursuant to the asset purchase agreement (the Fujifilm Transaction). The closing of the Fujifilm Transaction occurred on April 4, 2022, at which time 136 of our ATOM Facility employees transitioned to FDB as part of the transaction. We also entered into a Master Services and Supply Agreement and related Statements of Work with FDB (collectively, the Fujifilm MSA) which became effective upon the closing and could extend for up to ten years. Pursuant to the Fujifilm MSA, FDB will supply us with specified quantities of our cell therapy product candidates and any products approved by regulatory authorities, manufactured in accordance with cGMP standards. See Note 8 for further information. Certain prior year amounts, which are not material, have been reclassified to conform to current year presentation in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss), Condensed Consolidated Statements of Cash Flows and the Notes to Condensed Consolidated Financial Statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements include the accounts of Atara and its wholly owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These unaudited interim condensed consolidated financial statements should therefore be read in conjunction with the audited consolidated financial statements and notes for the year ended December 31, 2022, included in the Company’s Annual Report on Form 10-K filed with the SEC on February 8, 2023. In the opinion of management, the condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair presentation of the Company’s condensed consolidated financial statements. The results of operations for any interim period are not necessarily indicative of the results to be expected for the full year or any other future period. The condensed consolidated balance sheet as of December 31, 2022 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete consolidated financial statements. Liquidity and Going Concern We have incurred significant operating losses since inception and have relied primarily on public and private equity financings and receipts from license and collaboration agreements to fund our operations. As we continue to incur losses, our transition to profitability will depend on the successful development, approval and commercialization of product candidates and on the achievement of sufficient revenues to support our cost structure. We may never achieve sustained operating cash inflows or profitability. We expect that existing cash, cash equivalents and short-term investments as of September 30, 2023, will not be sufficient to fund our planned operations for at least the next twelve months from the date of issuance of these condensed consolidated financial statements. These conditions raise substantial doubt about our ability to continue as a going concern for at least 12 months after the date these condensed consolidated financial statements are issued. The interim condensed consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty. To alleviate the conditions that raise substantial doubt about our ability to continue as a going concern, we plan to secure additional capital, potentially through a combination of public or private security offerings; use of our ATM facilities as described in Note 9; and/or strategic transactions. We may also need to raise additional funding as required based on the status of our development programs and our projected cash flows. Although we have been successful in raising capital in the past, and expect to continue to raise capital as required, there is no assurance that we will be successful in obtaining sufficient funding on terms acceptable to us to fund continuing operations, if at all, or identify and enter into any strategic transactions that will provide the capital that we will require. If we are unable to obtain sufficient funding on acceptable terms, we could be forced to delay, limit, reduce or terminate preclinical studies, clinical studies or other development activities for one or more of our product candidates, which could have a material adverse effect on our business, results of operations, and financial condition. Accordingly, we have concluded that substantial doubt exists with respect to our ability to continue as a going concern for at least 12 months after the issuance of the accompanying condensed consolidated financial statements. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates, assumptions and judgments that affect the amounts reported in the financial statements and accompanying notes. Significant estimates relied upon in preparing these financial statements include estimates related to revenue recognition, accrued research and development expenses, stock-based compensation expense, income taxes and the liability related to the sale of future revenues. Actual results could differ materially from those estimates. Recent Accounting Pronouncements We consider the applicability and impact of any recent Accounting Standards Update (ASU) issued by the Financial Accounting Standards Board (FASB). Based on our assessment, the ASUs were determined to be either not applicable or are expected to have minimal impact on our condensed consolidated financial statements.

Net Loss per Common Share

Net Loss per Common Share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Net Loss per Common Share	3. Net Loss per Common Share Basic net loss per common share is calculated by dividing net loss by the weighted-average number of shares of common stock and pre-funded warrants outstanding during the period, without consideration of common share equivalents. Diluted net loss per common share is computed by dividing net loss by the weighted-average number of shares of common stock, pre-funded warrants and common share equivalents outstanding for the period. The pre-funded warrants are included in the computation of basic and diluted net loss per common share as the exercise price is negligible and the pre-funded warrants are fully vested and exercisable. Common share equivalents are only included in the calculation of diluted net loss per common share when their effect is dilutive. Potential dilutive securities, which include unvested restricted stock units (RSUs), unvested performance-based RSUs and performance-based options to purchase common stock for which established performance criteria have been achieved as of the end of the respective periods, vested and unvested options to purchase common stock and shares to be issued under our employee stock purchase plan (ESPP), have been excluded from the computation of diluted net loss per common share if the effect is antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in all periods presented. The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted net loss per common share, as their inclusion would have an antidilutive effect: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Unvested RSUs 8,456,088 7,915,826 8,456,088 7,915,826 Vested and unvested options 12,288,025 10,954,723 12,288,025 10,954,723 ESPP share purchase rights 473,549 264,967 473,549 264,967 Total 21,217,662 19,135,516 21,217,662 19,135,516

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2023
Financial Instruments Disclosure [Abstract]
Financial Instruments	4. Financial Instruments Our financial assets are measured at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable U.S. GAAP: Level 1: Quoted prices in active markets for identical assets or liabilities that we have the ability to access Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data such as quoted prices, interest rates and yield curves Level 3: Inputs that are unobservable data points that are not corroborated by market data We review the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels of certain securities within the fair value hierarchy. We recognize transfers into and out of levels within the fair value hierarchy in the period in which the actual event or change in circumstances that caused the transfer occurs. There have been no transfers between Level 1, Level 2 and Level 3 in any periods presented. Financial assets and liabilities are considered Level 2 when their fair values are determined using inputs that are observable in the market or can be derived principally from or corroborated by observable market data such as pricing for similar securities, recently executed transactions, cash flow models with yield curves, and benchmark securities. In addition, Level 2 financial instruments are valued using comparisons to like-kind financial instruments and models that use readily observable market data as their basis. U.S. Treasury, government agency and corporate debt obligations, commercial paper and asset-backed securities are valued primarily using market prices of comparable securities, bid/ask quotes, interest rate yields and prepayment spreads and are included in Level 2. Financial assets and liabilities are considered Level 3 when their fair values are determined using pricing models, discounted cash flow methodologies, or similar techniques, and at least one significant model assumption or input is unobservable. We have no Level 3 financial assets or liabilities. The following tables summarize the estimated fair value and related valuation input hierarchy of our available-for-sale securities as of each period end: Total Total Total Total Amortized Unrealized Unrealized Estimated As of September 30, 2023: Input Level Cost Gain Loss Fair Value (in thousands) Money market funds Level 1 $ 35,230 $ — $ — $ 35,230 U.S. Treasury obligations Level 2 28,318 4 — $ 28,322 Government agency obligations Level 2 1,451 — ( 26 ) $ 1,425 Corporate debt obligations Level 2 34,018 — ( 509 ) $ 33,509 Asset-backed securities Level 2 2,723 — ( 40 ) $ 2,683 Total available-for-sale securities 101,740 4 ( 575 ) 101,169 Less: amounts classified as cash equivalents ( 63,548 ) ( 4 ) — ( 63,552 ) Amounts classified as short-term investments $ 38,192 $ — $ ( 575 ) $ 37,617 Total Total Total Total Amortized Unrealized Unrealized Estimated As of December 31, 2022: Input Level Cost Gain Loss Fair Value (in thousands) Money market funds Level 1 $ 78,033 $ — $ — $ 78,033 U.S. Treasury obligations Level 2 63,013 3 ( 394 ) 62,622 Government agency obligations Level 2 8,086 — ( 48 ) 8,038 Corporate debt obligations Level 2 82,598 4 ( 1,513 ) 81,089 Commercial paper Level 2 996 — — 996 Asset-backed securities Level 2 6,343 — ( 119 ) 6,224 Total available-for-sale securities 239,069 7 ( 2,074 ) 237,002 Less: amounts classified as cash equivalents ( 87,122 ) ( 3 ) — ( 87,125 ) Amounts classified as short-term investments $ 151,947 $ 4 $ ( 2,074 ) $ 149,877 The amortized cost and fair value of our available-for-sale securities by contractual maturity were as follows: As of September 30, 2023 As of December 31, 2022 Amortized Estimated Amortized Estimated Cost Fair Value Cost Fair Value (in thousands) (in thousands) Maturing within one year $ 97,367 $ 96,863 $ 202,323 $ 201,359 Maturing in one to five years 4,373 4,306 36,746 35,643 Total available-for-sale securities $ 101,740 $ 101,169 $ 239,069 $ 237,002 We considered the current and expected future global economic and market conditions, including, but not limited to, the wars in Ukraine and the Middle East and increased tensions between the U.S. and China, and determined that our investments have not been significantly impacted. As of September 30, 2023, no significant facts or circumstances were present to indicate a deterioration in the creditworthiness of the issuers of the available-for-sale securities we hold, and we have no requirement or intention to sell these securities before maturity or recovery of their amortized cost basis. For all securities with a fair value less than its amortized cost basis, we determined the decline in fair value below amortized cost basis to be non-credit related and no allowance for losses has been recorded. During the three and nine months ended September 30, 2023 and 2022, we did not recognize any impairment losses on our investments. We have elected the practical expedient to exclude the applicable accrued interest from both the fair value and the amortized cost basis of our available-for-sale securities for purposes of identifying and measuring an impairment. We present accrued interest receivable related to our available-for-sale securities in other current assets, separate from short-term investments, on our condensed consolidated balance sheet. As of September 30, 2023 and December 31, 2022 , accrued interest receivable was $ 0.4 million and $ 0.8 million, respectively. We have no t written off any accrued interest receivables during the three and nine months ended September 30, 2023 and 2022. In addition, restricted cash collateralized by money market funds is a financial asset measured at fair value and is a Level 1 financial instrument under the fair value hierarchy. The following table provides a reconciliation of cash, cash equivalents and restricted cash within the condensed consolidated balance sheets that sum to the total of the same such amounts in the condensed consolidated statement of cash flows: September 30, December 31, 2023 2022 (in thousands) Cash and cash equivalents $ 64,791 $ 92,942 Restricted cash – short term 146 146 Total cash, cash equivalents and restricted cash $ 64,937 $ 93,088

Out-license Agreements

Out-license Agreements	9 Months Ended
	Sep. 30, 2023
License Collaboration And Manufacturing Agreements [Abstract]
Out-license Agreements	5. Out-license Agreements Pierre Fabre Agreements In October 2021, we entered into the Pierre Fabre Commercialization Agreement, pursuant to which we granted to Pierre Fabre an exclusive, field-limited license to commercialize and distribute Ebvallo in Europe and select emerging markets in the Initial Territory following regulatory approval. Atara retains full rights to Ebvallo in other major markets, including North America, Asia Pacific and Latin America. In September 2022, we entered into Amendment No. 1 to the Pierre Fabre Commercialization Agreement (the PF Amendment). Under the terms of the PF Amendment, following European Commission approval of Ebvallo for EBV+ PTLD and subsequent filing of the Marketing Authorization Application (MAA) transfer to Pierre Fabre, we received an additional $ 30 million milestone payment in exchange for, among other things, a reduction in: (i) royalties we are eligible to receive as a percentage of net sales of Ebvallo in the Initial Territory, and (ii) the supply price mark up on Ebvallo purchased by Pierre Fabre. Additionally, we also agreed to extend the time period for provision of certain services to Pierre Fabre under the Pierre Fabre Commercialization Agreement. In December 2022, we sold a portion of our right to receive royalties and certain milestones in Ebvallo under the Pierre Fabre Commercialization Agreement to HCR Molag Fund L.P. (HCRx) for a total investment amount of $ 31.0 million, subject to a repayment cap between 185 % and 250 % of the total investment amount by HCRx. See Note 6 for further information related to the agreement with HCRx. In October 2023, we amended and restated the Pierre Fabre Commercialization Agreement. See Note 11 for further information. Pursuant to the Pierre Fabre Commercialization Agreement, we are responsible at our cost for the conclusion of the ongoing Phase 3 ALLELE clinical study and the Phase 2 multi-cohort clinical study. We are also responsible at our cost for certain other activities directed to obtaining regulatory approval for Ebvallo for EBV-associated post-transplant lymphoproliferative disease pursuant to the terms of the Pierre Fabre Commercialization Agreement in Europe. Pierre Fabre is responsible at its cost for obtaining and maintaining all other regulatory approvals and for commercialization and distribution of Ebvallo in the Initial Territory. We will own any intellectual property rights developed solely by us under the Pierre Fabre Commercialization Agreement. We have formed a joint steering committee (JSC) with Pierre Fabre that provides oversight, decision making and implementation guidance regarding the commercialization activities covered under the Pierre Fabre Commercialization Agreement. Pierre Fabre paid us an upfront cash payment of $ 45.0 million for the exclusive license grant in the fourth quarter of 2021. In December 2022, we met the contractual right to receive $ 40.0 million in milestone payments upon certain regulatory milestones, for which the cash was received in January 2023. Subject to the terms of the royalty purchase agreement with HCRx, as described in Note 6, we are entitled to receive an aggregate of up to $ 308.0 million in remaining milestone payments upon achieving certain regulatory and commercial milestones in addition to double-digit tiered royalties as a percentage of net sales of Ebvallo, until the later of 12 years after the first commercial sale in each such country, the expiration of specified patent rights, or the expiration of all regulatory exclusivity for such product on a country-by-country basis. We have entered into a separate manufacturing and supply agreement with Pierre Fabre for us to manufacture Ebvallo for Pierre Fabre to use in the Initial Territory based on a fixed price through December 31, 2023 and at a price equal to cost plus a margin for orders placed after December 31, 2023, subject to a maximum annual increase. At Pierre Fabre’s cost, we are responsible for manufacturing and supplying Pierre Fabre’s optional purchases of Ebvallo for commercialization in the Initial Territory for a minimum of seven years from the first commercial sale, as defined in the Pierre Fabre Commercialization Agreement, of Ebvallo in the Initial Territory. At any time following this period, we have the option to transfer the manufacturing responsibility and related manufacturing technology to a third party contract manufacturing organization (CMO), and Pierre Fabre may also elect to directly assume the manufacturing responsibility and receive the related manufacturing technology. Without transfer of the manufacturing technology, no other party can perform this obligation. We are also responsible for cell selection services for Pierre Fabre at our cost for a certain period of time unless the parties agree to transfer the related cell selection technology to Pierre Fabre prior to this date. Cell selection is the process of identifying the appropriate cell line from available inventory to be used for a patient. Without transfer of the cell selection technology, no other party can provide such services. After this period of time, if we agree to continue to provide cell selection services, it shall be at the sole expense of Pierre Fabre. We assessed this arrangement in accordance with ASC 606 and concluded that the promises in the Pierre Fabre Commercialization Agreement represent transactions with a customer. We concluded that the Pierre Fabre Commercialization Agreement includes promises related to the transfer of intellectual property rights in the form of a license, the obligation to participate in the JSC and a material right for optional purchases associated with the manufacture and supply of Ebvallo and the performance of cell-selection services. We concluded that the individual promises are not distinct because Pierre Fabre cannot benefit from the license without the other services and vice versa, since Pierre Fabre is not capable of carrying out the manufacturing and supply and cell selection services on their own, until, and if, the transfer of the related technologies occur. Consequently, the license, the participation in the JSC and the material right related to the manufacture and supply of Ebvallo and related cell selection represents a single performance obligation. Under the Pierre Fabre Commercialization Agreement, we determined that the $ 45.0 million upfront payment constituted the entire consideration to be included in the transaction price at the outset of the arrangement. The $ 40.0 million in development milestones met in December 2022 were added to the transaction price upon meeting the related milestone criteria. The associated commercialization revenue will be recognized over the period during which the material right to these services exists, which would end if the option to transfer the manufacturing technology, once contractually available, is executed. Based on these considerations and our forecast of the timing and associated costs of the optional purchases related to the manufacture and supply of Ebvallo, we estimate the material right related to these services will exist for approximately 12 years. We reassess this evaluation each reporting period. The remaining potential development and commercial milestone payments that we are eligible to receive were excluded from the transaction price, as the milestone amounts were fully constrained based on the probability of achievement or have not been earned. None of the future royalty and sales-based milestone payments were included in the transaction price, as the potential payments represent sales-based consideration. We reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, if necessary, adjust our estimate of the transaction price. In January 2023, the first order of Ebvallo was shipped to Pierre Fabre. Commercialization revenue associated with shipments of Ebvallo to Pierre Fabre is deferred until we have performed the associated cell selection services. Deferred revenue activity related to commercialization revenue for the nine months ended September 30, 2023 was as follows: (in thousands) Deferred revenue, December 31, 2022 $ 85,000 Additions 4,174 Recognized into commercialization revenue ( 3,634 ) Deferred revenue September 30, 2023 85,540 Less: deferred revenue – current portion ( 11,611 ) Deferred revenue – long-term, September 30, 2023 $ 73,929 During the nine months ended September 30, 2023 , we recognized $ 3.0 million of revenue that was included in the deferred revenue balance as of December 31, 2022. Cost of commercialization revenue consists primarily of expenses associated with cell selection services performed for Pierre Fabre, in-license sales-related milestone costs, period manufacturing expenses and the lower of cost or net realizable value adjustments to inventories. All Ebvallo sold to Pierre Fabre to date had been produced prior to receiving regulatory approval of Ebvallo. Costs incurred to produce Ebvallo prior to regulatory approval, referred to as zero cost inventories, have been recorded as research and development expense in our condensed consolidated statement of operations and comprehensive income (loss). Once we begin selling Ebvallo produced after receiving regulatory approval and in a qualified manufacturing facility, and as revenue is recognized on such Ebvallo shipments, cost of commercialization revenue will also include direct and indirect costs related to the production of Ebvallo. Such costs include, but are not limited to, CMO costs, quality testing and validation, materials used in production, and an allocation of compensation, benefits and overhead costs associated with employees involved with production. Under the Pierre Fabre Commercialization Agreement, we conduct an early access program observational study at the sole cost and expense of Pierre Fabre. We recognize the costs incurred associated with this study within research and development expenses, which is directly offset by revenue recorded within license and collaboration revenue. The license and collaboration revenue associated with the early access program for the three and nine months ended September 30, 2023 was $ 0.1 million and $ 0.6 million, respectively, as compared to $ 0.2 million and $ 1.6 million for the three and nine months ended September 30, 2022, respectively. Bayer Agreements In December 2020, we entered into a research, development and license agreement (Bayer License Agreement) with Bayer AG (Bayer) pursuant to which we granted to Bayer an exclusive, field-limited license under the applicable patents and know-how owned or controlled by us and our affiliates covering or related to ATA2271 and ATA3271 (the Licensed Products). Under the terms of the Bayer License Agreement, we were responsible at our cost for all mutually agreed preclinical and clinical activities for ATA2271 through the first in human Phase 1 clinical study in collaboration with MSK, following which Bayer was responsible for the further development of ATA2271 at its cost. Bayer was responsible for the development of ATA3271, except for certain mutually agreed preclinical, translational, manufacturing and supply chain activities to be performed by us relating to ATA3271, in each case at Bayer’s cost. Bayer was also solely responsible for commercializing the Licensed Products at its cost. In March 2021, we entered into a Technology Transfer Agreement with Bayer (the Bayer Tech Transfer Agreement), which was contemplated as part of the Bayer License Agreement, to transfer to Bayer the ATA3271 manufacturing process being developed as part of the CMC services in the Bayer License Agreement. In March 2021, we also entered into a Manufacturing and Supply Agreement with Bayer (the Bayer Manufacturing Agreement), which was contemplated as part of the Bayer License Agreement, to manufacture Phase 1 and 2 allogeneic mesothelin-directed CAR T-cell therapies for Bayer to use in clinical trials at a price based on our costs plus a reasonable margin, which is consistent with our standalone selling price. Collectively, the Bayer License Agreement, the Manufacturing and Supply Agreement and the Technology Transfer Agreement are referred to as “the Bayer Agreements”. In May 2022, Bayer notified us of its decision to terminate the Bayer Agreements, and on August 2, 2022, we entered into the Termination, Amendment and Program Transfer Agreement with which terminated the Bayer Agreements (the Bayer Termination Agreement) with an effective date of July 31, 2022. Upon the termination effective date, full product development and commercialization rights related to ATA2271 and ATA3271 reverted to Atara. In return for certain activities performed by Atara prior to the termination effective date, Bayer paid Atara $ 4.2 million in September 2022. Utilizing the cost-based input method, we recognized license and collaboration revenue of $ 4.2 million and $ 61.8 million for the three and nine months ended September 30, 2022 , respectively, under the Bayer Agreements. As a result of the termination, no license and collaboration revenue related to the Bayer Agreements was recognized for the three and nine months ended September 30, 2023 , and there was no deferred revenue related to the Bayer Agreements as of September 30, 2023 or December 31, 2022 .

Liability Related to the Sale o

Liability Related to the Sale of Future Revenues	9 Months Ended
	Sep. 30, 2023
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Liability Related to the Sale of Future Revenues	6. Liability Related to the Sale of Future Revenues In December 2022, we entered into a Purchase and Sale Agreement (the HCRx Agreement) with HCR Molag Fund, L.P., a Delaware limited partnership, (HCRx). In exchange for a payment of $ 31.0 million (the Investment Amount), net of certain transaction expenses, to Atara, HCRx obtained the right to receive certain Ebvallo royalties and milestone payments payable by Pierre Fabre under the Pierre Fabre Commercialization Agreement up to an agreed upon multiple of the Investment Amount. We received the Investment Amount, net of certain transaction costs, from HCRx on December 30, 2022. Under the HCRx Agreement, HCRx is entitled to receive tiered royalties on net sales of Ebvallo in the Initial Territory in amounts ranging from the mid-single digits to double digits based on annual net sales. HCRx is also entitled to certain milestone payments due to Atara from Pierre Fabre. The total royalties and milestones payable to HCRx are capped between 185 % and 250 % of the Investment Amount, depending upon the timing of such royalties and milestones. Upon meeting the cap amount, HCRx’s right to receive royalties and milestone payments will terminate and all rights will revert to Atara. To the extent a certain milestone within the Pierre Fabre Commercialization Agreement is not achieved on or prior to June 30, 2026, we will be required to make a one-time cash payment in the amount of $ 9.0 million to HCRx, and HCRx shall transfer all of its right, title and interest in this certain $ 9.0 million milestone payment to Atara. This payment, if required, would be included in the calculation of aggregate payments made to HCRx. The gross proceeds of the Investment Amount of $ 31.0 million were recorded as a liability related to the sale of future revenues, net of transaction costs of $ 0.4 million, and will be amortized using the effective interest method over the life of the arrangement. To determine the amortization of the recorded liability, we are required to estimate the total amount of future payments to be received by HCRx. The sum of these amounts less the $ 31.0 million proceeds we received will be recorded as interest expense over the life of the HCRx Agreement. We estimate the effective interest rate used to record non-cash interest expense under the HCRx Agreement based on the estimate of future payments to be received by HCRx. At September 30, 2023 , the annual effective interest rate was approximately 15 %. Over the life of the arrangement, the actual effective interest rate will be affected by the amount and timing of the actual and forecasted royalty and milestone payments to HCRx. At each reporting date, we will reassess our estimate of the timing and amounts of future payments made to HCRx, and prospectively adjust the effective interest rate and amortization of the liability as necessary. The following table presents the changes in the liability related to the sale of future revenues under the HCRx Agreement for the nine months ended September 30, 2023: (in thousands) Liability related to sale of future revenues as of December 31, 2022 $ 30,236 Accretion of interest expense on liability related to sale of future revenues 3,729 Amortization of debt discount and debt issuance costs 61 Repayment of the liability ( 11 ) Liability related to sale of future revenues as of September 30, 2023 34,015 Less: current portion classified within other accrued liabilities ( 763 ) Long-term liability related to sale of future revenues $ 33,252

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Restructuring	7. Restructuring In August 2022, we announced a reduction in workforce of approximately 20 % to focus our activities as an organization centered on research and development. The workforce reduction included total restructuring charges of $ 6.0 million, comprised primarily of severance payments, wages for the 60-day notice period in accordance with the California Worker Adjustment and Retraining Notification Act and continuing health care coverage for a period of time after separation. In most cases, the severance payments were paid as a lump sum in October 2022. Certain of the notified employees had employment agreements which provided for separation benefits in the form of salary continuation; these benefits are being paid between October 2022 and November 2023. All of the costs are cash expenditures and primarily represent one-time termination benefits. We recorded the following restructuring charges associated with the reduction in force: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (in thousands) (in thousands) (in thousands) Research and development expense $ — $ 2,710 $ — $ 2,710 General and administrative expense — 3,180 45 3,180 Total restructuring charges $ — $ 5,890 $ 45 $ 5,890 The following restructuring liability activity was recorded in connection with the reduction in force for the nine months ended September 30, 2023: (in thousands) Liability balance, December 31, 2022 $ 1,545 Restructuring charges 45 Cash payments ( 1,513 ) Liability balance, September 30, 2023 $ 77 The liability balance as of September 30, 2023 and December 31, 2023 is recorded within other current liabilities on the accompanying condensed consolidated balance sheet.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies MSK In-license Agreements In June 2015, we entered into an exclusive license agreement with MSK for three clinical stage T-cell therapies. We are required to make payments to MSK based on achievement of specified regulatory and sales-related milestones, as well as mid-single-digit percentage tiered royalty payments based on future sales of products resulting from the development of the licensed product candidates, if any. In addition, under certain circumstances, we are required to make certain minimum annual royalty payments to MSK, which are creditable against earned royalties owed for the same annual period. We are also required to pay a low double-digit percentage of any consideration we receive for sublicensing the licensed rights. The license agreement expires on a product-by-product and country-by-country basis on the latest of: (i) expiration of the last licensed patent rights related to each licensed product, (ii) expiration of any market exclusivity period granted by law with respect to each licensed product, and (iii) a specified number of years after the first commercial sale of the licensed product in each country. Upon expiration of the license agreement, Atara will retain non-exclusive rights to the licensed products. In May and December 2018, we licensed additional technology from MSK. We are obligated to make additional milestone payments based on achievement of specified development, regulatory and sales-related milestones, as well as mid-single-digit percentage tiered royalty payments based on future sales of products resulting from the development of the licensed product candidates, if any. In March 2021, we amended and restated our license agreement with MSK to terminate our license to certain rights and license additional know-how rights not otherwise covered by our existing agreements. QIMR Berghofer In-license Agreements In October 2015, we entered into an exclusive license agreement and a research and development collaboration agreement with QIMR Berghofer. Under the terms of the license agreement, we obtained an exclusive, worldwide license to develop and commercialize allogeneic T-cell therapy programs utilizing technology and know-how developed by QIMR Berghofer. On September 19, 2016, the exclusive license agreement and research and development collaboration agreement were amended and restated. Under the amended and restated agreements, we obtained an exclusive, worldwide license to develop and commercialize additional T-cell programs, as well as the option to license additional technology that we exercised in June 2018. We further amended and restated our license agreement and research and development collaboration agreements with QIMR Berghofer in August 2019, August 2020, and in December 2021, in each case, to terminate our license to certain rights. Our current license agreement also provides for various milestone and royalty payments to QIMR Berghofer based on future product sales, if any. Under the terms of our current research and development collaboration agreement, we are also required to reimburse the cost of agreed-upon development activities related to programs developed under the collaboration. These payments are expensed on a straight-line basis over the related development periods. The agreement also provides for various milestone payments to QIMR Berghofer based on achievement of certain developmental and regulatory milestones. Other In-license and Collaboration Agreements From time to time, we have entered into other license and collaboration agreements with other parties. For example, we licensed rights related to our MSK-partnered next-generation CAR T programs from the National Institutes of Health in December 2018. Milestones and royalties under each of the above agreements are contingent upon future events and will be recorded as expense when the underlying milestones are achieved or royalties are earned. Sales related milestone and royalty costs related to Ebvallo are recorded in cost of commercialization revenue, whereas regulatory milestone costs are recorded in research and development expense. As of September 30, 2023 and December 31, 2022 , there were no material outstanding obligations for milestones and royalties under our license and collaboration agreements. CRL Manufacturing Agreement In December 2019, we entered into a Commercial Manufacturing Services Agreement (the CRL MSA) with Cognate BioServices, Inc., which was acquired by Charles River Laboratories Inc. (CRL) in March 2021. Pursuant to the CRL MSA, CRL provides manufacturing services for our product and certain of our product candidates. In September 2023, we amended the CRL MSA to extend the term until the earlier of December 31, 2023 or receipt of certain batches of our product and product candidates. Fujifilm Master Services and Supply Agreement In January 2022, we entered into the Fujifilm MSA, which became effective upon the closing of the sale of the ATOM Facility on April 4, 2022 and could extend for up to ten years . Pursuant to the Fujifilm MSA, FDB will supply us with specified quantities of our cell therapy products and product candidates, manufactured in accordance with cGMP standards. We have certain non-cancellable minimum commitments to purchase products and services over the first five years of the Fujifilm MSA. The Fujifilm MSA does not obligate us to purchase products and product candidates exclusively from FDB. Other Research, Development and Manufacturing Agreements We may enter into other contracts in the normal course of business with clinical research organizations for clinical trials, with CMOs for clinical supplies, and with other vendors for preclinical studies, supplies and other services for our operating purposes. These contracts generally provide for termination on notice. As of September 30, 2023 and December 31, 2022 , there were no material amounts accrued related to contract termination charges. Minimum Commitments We have non-cancellable minimum commitments for products and services, subject to agreements with a term of greater than one year with clinical research organizations and CMOs. We have incurred $2 .8 million and $ 16.1 million against the minimum commitments for the three and nine months ended September 30, 2023, respectively. As of September 30, 2023, and December 31, 2022, we have accrued $ 11.0 million and $ 9.2 million, respectively, in research and development expenses related to minimum purchase commitments. Indemnification Agreements In the normal course of business, we enter into contracts and agreements that contain a variety of representations and warranties and provide for indemnification for certain liabilities. The exposure under these agreements is unknown because it involves claims that may be made against us in the future but have not yet been made. To date, we have not paid any claims or been required to defend any action related to our indemnification obligations. However, we may record charges in the future as a result of these indemnification obligations. We also have indemnification obligations to our directors and executive officers for specified events or occurrences, subject to some limits, while they are serving at our request in such capacities. There have been no claims to date and we consider the fair value of these indemnification agreements to be minimal. Accordingly, we did no t record liabilities for these agreements as of September 30, 2023 and December 31, 2022. Contingencies From time to time, we may be involved in legal proceedings, as well as demands, claims and threatened litigation, which arise in the normal course of our business or otherwise. The ultimate outcome of any litigation is uncertain and unfavorable outcomes could have a negative impact on our results of operations and financial condition. Regardless of outcome, litigation can have an adverse impact on us because of the defense costs, diversion of management resources and other factors. We are not currently involved in any material legal proceedings.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stockholders' Equity (Deficit)	9. Stockholders’ Equity (Deficit) Our authorized capital stock consists of 520,000,000 shares, all with a par value of $ 0.0001 per share, of which 500,000,000 shares are designated as common stock and 20,000,000 shares are designated as preferred stock. There were no shares of preferred stock outstanding as of September 30, 2023 and December 31, 2022. Equity Offerings As part of our July 2019 underwritten public offering, we issued and sold pre-funded warrants to purchase 2,945,026 shares of common stock in an underwritten public offering pursuant to a shelf registration on Form S-3. Each pre-funded warrant entitles the holder to purchase one share of common stock at an exercise price of $ 0.0001 per share and expires seven years from the date of issuance. These warrants were recorded as a component of stockholders’ equity (deficit) within additional paid-in capital. Per the terms of the warrant agreement, a holder of the outstanding warrants is not entitled to exercise any portion of any pre-funded warrant if, upon exercise of the warrant, the holder’s ownership (together with its affiliates) of our common stock or combined voting power of our securities beneficially owned by such holder (together with its affiliates) would exceed 9.99 % after giving effect to the exercise (Maximum Ownership Percentage). Upon at least 61 days’ prior notice to us by the holder, any holder may increase or decrease the Maximum Ownership Percentage to any other percentage not to exceed 19.99 %. No July 2019 pre-funded warrants were exercised during the three months ended September 30, 2023. During the nine months ended September 30, 2023 , 361,260 of the July 2019 pre-funded warrants were exercised and as of September 30, 2023 pre-funded warrants to purchase 2,527,266 shares of our common stock from the July 2019 underwritten public offering were outstanding. As part of the May 2020 underwritten public offering, we issued and sold pre-funded warrants to purchase 2,866,961 shares of common stock in an underwritten public offering pursuant to a shelf registration on Form S-3. Additionally, as part of the December 2020 underwritten public offering, we issued and sold pre-funded warrants to purchase 2,040,816 shares of common stock in an underwritten public offering pursuant to a shelf registration on Form S-3. The terms of the pre-funded warrants issued and sold as part of the 2020 public offerings were similar to those issued and sold in 2019. No May 2020 or December 2020 pre-funded warrants were exercised during the three months ended September 30, 2023. During the nine months ended September 30, 2023 , 1,898,578 and 656,107 of the May 2020 and December 2020 pre-funded warrants, respectively, were exercised. As of September 30, 2023 , 968,383 and 1,384,709 of the pre-funded warrants to purchase shares of our common stock issued and sold as part of the May 2020 and December 2020 underwritten public offerings, respectively, were outstanding. ATM Facilities In November 2021, we entered into a sales agreement (the 2021 ATM Facility) with Cowen and Company, LLC (Cowen), which provides for the sale, in our sole discretion, of shares of our common stock having an aggregate offering price of up to $ 100.0 million through Cowen, as our sales agent. The issuance and sale of these shares by us pursuant to the 2021 ATM Facility are deemed “at the market” offerings as defined in Rule 415 under the Securities Act of 1933, as amended (the Securities Act), and are registered under the Securities Act. We pay a commission of up to 3.0 % of gross sales proceeds of any common stock sold under the 2021 ATM Facility. During the nine months ended September 30, 2023 , we sold an aggregate of 147,930 shares of common stock under the 2021 ATM Facility, at an average price of $ 4.64 per share, for gross proceeds of $ 0.7 million and net proceeds of $ 0.6 million, after deducting commissions and other offering expenses payable by us. As of September 30, 2023 , $ 55.2 million of common stock remained available to be sold under the 2021 ATM Facility, subject to certain conditions as specified in the sales agreement. In November 2023, we entered into a sales agreement (the 2023 ATM Facility) with Cowen, which provides for the sale, in our sole discretion, of shares of our common stock having an aggregate offering price of up to $ 100.0 million through Cowen, as our sales agent. The issuance and sale of these shares by us pursuant to the 2023 ATM Facility are deemed “at the market” offerings as defined in Rule 415 under the Securities Act, and we intend to file a registration statement on Form S-3 registering the offer and sale of these shares under the Securities Act (the 2023 Registration Statement). We pay a commission of up to 3.0 % of gross sales proceeds of any common stock sold under the 2023 ATM Facility. Upon the effectiveness of the 2023 Registration Statement, the 2021 ATM Facility will terminate, and no further sales will be made under the 2021 ATM Facility. Equity Incentive Plans Under the terms of the 2014 Equity Incentive Plan, as amended (the 2014 EIP), we may grant stock options, restricted stock awards (RSAs) and RSUs to employees, directors, consultants and other service providers. RSUs generally vest over three or four years . We have granted performance-based RSUs to certain of our employees that provide for the issuance of common stock if specified Company performance criteria related to our clinical programs are achieved. The number of performance-based RSUs that ultimately vests depends upon if and which performance criteria are achieved, as well as the employee’s continuous service, as defined in the 2014 EIP, through the date of vesting. The fair value of performance-based RSUs is determined as the closing stock price on the date of grant. Stock options are granted at prices no less than 100 % of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided, however, that the exercise price of an option granted to a 10% shareholder cannot be less than 110% of the estimated fair value of the shares on the date of grant. Options granted generally vest over three or four years and expire in seven to ten years . We have granted performance-based stock options to certain of our employees that provide for the issuance of a right to purchase a share of common stock if specified Company performance criteria related to product candidate partnerships are achieved. The vesting of performance-based stock options depends upon if and when the performance criteria are achieved, as well as the employee’s continuous service as defined in the 2014 EIP, through the date of vesting. As of September 30, 2023 , a total of 21,564,328 shares of common stock were reserved for issuance under the 2014 EIP, of which 3,549,685 shares were available for future grant and 18,014,643 shares were subject to outstanding options and RSUs, including performance-based awards. In February 2018, we adopted the 2018 Inducement Plan (the Inducement Plan), under which we may grant options, stock appreciation rights, RSAs and RSUs to new employees. In November 2020, September 2021 and June 2022 we amended the Inducement Plan to reserve an additional 1,500,000 shares of the Company’s common stock for issuance under the Inducement Plan in each case. As of September 30, 2023 , 4,847,270 shares of common stock were reserved for issuance under the Inducement Plan, of which 1,869,565 shares were available for future grant and 2,977,705 shares were subject to outstanding options and RSUs. Restricted Stock Units The following is a summary of RSU activity under our 2014 EIP and Inducement Plan: RSUs Shares Weighted Balance as of December 31, 2022 6,708,608 $ 10.61 Granted 5,472,166 $ 3.64 Forfeited ( 1,343,120 ) $ 8.52 Vested ( 2,375,066 ) $ 9.71 Balance as of September 30, 2023 8,462,588 $ 6.69 As of September 30, 2023 , there was $ 49.7 million of unrecognized stock-based compensation expense related to RSUs that is expected to be recognized over a weighted average period of 2.2 years. Stock Options The following is a summary of stock option activity under our 2014 EIP and Inducement Plan: Shares Weighted Average Weighted Average Aggregate Intrinsic Balance as of December 31, 2022 10,645,555 $ 16.88 6.4 $ 42 Granted 4,693,897 3.64 — — Exercised — — — — Forfeited or expired ( 2,809,692 ) 16.97 — — Balance as of September 30, 2023 12,529,760 $ 11.90 6.2 $ — Aggregate intrinsic value represents the difference between the closing stock price of our common stock on September 30, 2023 and the exercise price of outstanding, in-the-money options. As of September 30, 2023 , there was $ 23.4 million of unrecognized stock-based compensation expense related to stock options that is expected to be recognized over a weighted average period of 2.1 years. This excludes unrecognized stock-based compensation expense for performance-based stock options that were deemed not probable of vesting in accordance with U.S. GAAP. Reserved Shares The following shares of common stock were reserved for future issuance under our equity incentive plans as of September 30, 2023: Total Shares 2014 Equity Incentive Plan 21,564,328 2018 Inducement Plan 4,847,270 2014 Employee Stock Purchase Plan 332,735 Total reserved shares of common stock 26,744,333 Stock-based Compensation Expense The following is a summary of stock-based compensation expense for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (in thousands) (in thousands) Research and development $ 6,758 $ 7,986 $ 20,723 $ 24,361 General and administrative 4,385 6,037 14,736 18,114 Total stock-based compensation expense $ 11,143 $ 14,023 $ 35,459 $ 42,475

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	9 Months Ended
	Sep. 30, 2023
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	10. Supplemental Balance Sheet Information Inventories Inventories consisted of the following as of each period end: September 30, December 31, 2023 2022 (in thousands) Raw Materials $ 2,422 $ 1,214 Work-in-process 4,169 372 Total inventories $ 6,591 $ 1,586 Property and equipment, net Property and equipment consisted of the following as of each period end: September 30, December 31, 2023 2022 (in thousands) Leasehold improvements $ 904 $ 875 Lab equipment 15,361 14,797 Machinery and equipment 572 572 Computer equipment and software 1,279 1,149 Furniture and fixtures 1,258 1,297 Construction in progress 239 32 Property and equipment, gross 19,613 18,722 Less: accumulated depreciation ( 14,985 ) ( 12,422 ) Property and equipment, net $ 4,628 $ 6,300 Depreciation expense was $ 0.9 million and $ 1.1 million for the three months ended September 30, 2023 and 2022 , respectively, and $ 2.8 million and $ 3.8 million for the nine months ended September 30, 2023 and 2022, respectively. Other current liabilities Other current liabilities consisted of the following as of each period end: September 30, December 31, 2023 2022 (in thousands) Accrued operating expenses $ 8,299 $ 7,435 Current portion of operating lease liabilities 12,409 12,806 Current portion of finance lease liabilities 887 834 Interest payable 763 — Other accrued liabilities 211 319 Total other current liabilities $ 22,569 $ 21,394

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events Reduction in Force On November 1, 2023, we announced a reduction in force that will reduce our current workforce by approximately 30 %. We expect to recognize approximately $ 7.0 million in total for severance and related benefits for employees laid off under the reduction in force. These charges are primarily one-time termination benefits and are all cash charges. We may also incur other charges or cash expenditures not currently contemplated due to events that may occur as a result of, or associated with, the workforce reduction. Global Tab-cel Partnership On October 31, 2023, we entered into an amended and restated Pierre Fabre Commercialization Agreement (A&R Commercialization Agreement). Effectiveness of the A&R Commercialization Agreement is subject to the receipt of clearance under the Hart-Scott Rodino Antitrust Improvements Act of 1976. The A&R Commercialization Agreement is expected to take effect in December 2023. Pursuant to the A&R Commercialization Agreement, Pierre Fabre’s exclusive rights to research, develop, manufacture, commercialize and distribute tab-cel (Ebvallo) will be expanded to include all other countries in the world (Additional Territory) in addition to the Initial Territory (together, the Territory), subject to our performance of certain activities as described below. During the applicable period specified in the A&R Commercialization Agreement, we will be responsible, at Pierre Fabre’s cost, to continue conducting the ongoing Phase 3 ALLELE clinical study and the Phase 2 multi-cohort clinical study. We will also be responsible, at Pierre Fabre’s cost, for certain other activities directed to obtaining regulatory approval in the United States for tab-cel for EBV-associated post-transplant lymphoproliferative disease pursuant to the terms of the A&R Commercialization Agreement. Pierre Fabre will be responsible, at its cost, for obtaining and maintaining all other required regulatory approvals and for commercialization and distribution of tab-cel in the Additional Territory, including conducting any other clinical study required. Prior to the transfer of manufacturing responsibility to Pierre Fabre, we will be responsible for manufacturing and supplying tab-cel to Pierre Fabre for commercialization in the Territory, at Pierre Fabre’s cost. After manufacturing responsibility is transferred to Pierre Fabre and for the remainder of the term of the A&R Commercialization Agreement, Pierre Fabre will be responsible, at its cost, for the manufacture and supply of tab-cel for commercialization in the Territory. Pursuant to the A&R Commercialization Agreement, Pierre Fabre will pay us an additional upfront cash payment of $ 20.0 million for the expanded exclusive license grant. We will also be entitled to receive an aggregate of up to $ 620.0 million in additional milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Additional Territory. In addition, we will be eligible to receive double-digit tiered royalties as a percentage of net sales of tab-cel (Ebvallo) in the Territory until the later of 12 years after the first commercial sale in such country, the expiration of specified patent rights in such country, or the expiration of all regulatory exclusivity for such Product in such country. Royalty payments may be reduced in certain specified customary circumstances. Royalties and milestones from the commercialization of Ebvallo in the Initial Territory remain subject to the HCRx Agreement.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements include the accounts of Atara and its wholly owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These unaudited interim condensed consolidated financial statements should therefore be read in conjunction with the audited consolidated financial statements and notes for the year ended December 31, 2022, included in the Company’s Annual Report on Form 10-K filed with the SEC on February 8, 2023. In the opinion of management, the condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair presentation of the Company’s condensed consolidated financial statements. The results of operations for any interim period are not necessarily indicative of the results to be expected for the full year or any other future period. The condensed consolidated balance sheet as of December 31, 2022 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete consolidated financial statements.
Liquidity and Going Concern	Liquidity and Going Concern We have incurred significant operating losses since inception and have relied primarily on public and private equity financings and receipts from license and collaboration agreements to fund our operations. As we continue to incur losses, our transition to profitability will depend on the successful development, approval and commercialization of product candidates and on the achievement of sufficient revenues to support our cost structure. We may never achieve sustained operating cash inflows or profitability. We expect that existing cash, cash equivalents and short-term investments as of September 30, 2023, will not be sufficient to fund our planned operations for at least the next twelve months from the date of issuance of these condensed consolidated financial statements. These conditions raise substantial doubt about our ability to continue as a going concern for at least 12 months after the date these condensed consolidated financial statements are issued. The interim condensed consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty. To alleviate the conditions that raise substantial doubt about our ability to continue as a going concern, we plan to secure additional capital, potentially through a combination of public or private security offerings; use of our ATM facilities as described in Note 9; and/or strategic transactions. We may also need to raise additional funding as required based on the status of our development programs and our projected cash flows. Although we have been successful in raising capital in the past, and expect to continue to raise capital as required, there is no assurance that we will be successful in obtaining sufficient funding on terms acceptable to us to fund continuing operations, if at all, or identify and enter into any strategic transactions that will provide the capital that we will require. If we are unable to obtain sufficient funding on acceptable terms, we could be forced to delay, limit, reduce or terminate preclinical studies, clinical studies or other development activities for one or more of our product candidates, which could have a material adverse effect on our business, results of operations, and financial condition. Accordingly, we have concluded that substantial doubt exists with respect to our ability to continue as a going concern for at least 12 months after the issuance of the accompanying condensed consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates, assumptions and judgments that affect the amounts reported in the financial statements and accompanying notes. Significant estimates relied upon in preparing these financial statements include estimates related to revenue recognition, accrued research and development expenses, stock-based compensation expense, income taxes and the liability related to the sale of future revenues. Actual results could differ materially from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements We consider the applicability and impact of any recent Accounting Standards Update (ASU) issued by the Financial Accounting Standards Board (FASB). Based on our assessment, the ASUs were determined to be either not applicable or are expected to have minimal impact on our condensed consolidated financial statements.

Net Loss per Common Share (Tabl

Net Loss per Common Share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Antidilutive Securities Excluded From Computation of Diluted Net Loss per Common Share	The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted net loss per common share, as their inclusion would have an antidilutive effect: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Unvested RSUs 8,456,088 7,915,826 8,456,088 7,915,826 Vested and unvested options 12,288,025 10,954,723 12,288,025 10,954,723 ESPP share purchase rights 473,549 264,967 473,549 264,967 Total 21,217,662 19,135,516 21,217,662 19,135,516

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2023
Financial Instruments Disclosure [Abstract]
Summary of Estimated Fair Value and Related Valuation Input Hierarchy of Available-for-Sale Securities	The following tables summarize the estimated fair value and related valuation input hierarchy of our available-for-sale securities as of each period end: Total Total Total Total Amortized Unrealized Unrealized Estimated As of September 30, 2023: Input Level Cost Gain Loss Fair Value (in thousands) Money market funds Level 1 $ 35,230 $ — $ — $ 35,230 U.S. Treasury obligations Level 2 28,318 4 — $ 28,322 Government agency obligations Level 2 1,451 — ( 26 ) $ 1,425 Corporate debt obligations Level 2 34,018 — ( 509 ) $ 33,509 Asset-backed securities Level 2 2,723 — ( 40 ) $ 2,683 Total available-for-sale securities 101,740 4 ( 575 ) 101,169 Less: amounts classified as cash equivalents ( 63,548 ) ( 4 ) — ( 63,552 ) Amounts classified as short-term investments $ 38,192 $ — $ ( 575 ) $ 37,617 Total Total Total Total Amortized Unrealized Unrealized Estimated As of December 31, 2022: Input Level Cost Gain Loss Fair Value (in thousands) Money market funds Level 1 $ 78,033 $ — $ — $ 78,033 U.S. Treasury obligations Level 2 63,013 3 ( 394 ) 62,622 Government agency obligations Level 2 8,086 — ( 48 ) 8,038 Corporate debt obligations Level 2 82,598 4 ( 1,513 ) 81,089 Commercial paper Level 2 996 — — 996 Asset-backed securities Level 2 6,343 — ( 119 ) 6,224 Total available-for-sale securities 239,069 7 ( 2,074 ) 237,002 Less: amounts classified as cash equivalents ( 87,122 ) ( 3 ) — ( 87,125 ) Amounts classified as short-term investments $ 151,947 $ 4 $ ( 2,074 ) $ 149,877
Amortized Cost and Fair Value of Available for Sale Securities by Contractual Maturity	The amortized cost and fair value of our available-for-sale securities by contractual maturity were as follows: As of September 30, 2023 As of December 31, 2022 Amortized Estimated Amortized Estimated Cost Fair Value Cost Fair Value (in thousands) (in thousands) Maturing within one year $ 97,367 $ 96,863 $ 202,323 $ 201,359 Maturing in one to five years 4,373 4,306 36,746 35,643 Total available-for-sale securities $ 101,740 $ 101,169 $ 239,069 $ 237,002
Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash within the condensed consolidated balance sheets that sum to the total of the same such amounts in the condensed consolidated statement of cash flows: September 30, December 31, 2023 2022 (in thousands) Cash and cash equivalents $ 64,791 $ 92,942 Restricted cash – short term 146 146 Total cash, cash equivalents and restricted cash $ 64,937 $ 93,088

Out-license Agreements (Tables)

Out-license Agreements (Tables)	9 Months Ended
	Sep. 30, 2023
License Collaboration And Manufacturing Agreements [Abstract]
Schedule of Deferred Revenue Activity	Deferred revenue activity related to commercialization revenue for the nine months ended September 30, 2023 was as follows: (in thousands) Deferred revenue, December 31, 2022 $ 85,000 Additions 4,174 Recognized into commercialization revenue ( 3,634 ) Deferred revenue September 30, 2023 85,540 Less: deferred revenue – current portion ( 11,611 ) Deferred revenue – long-term, September 30, 2023 $ 73,929

Liability Related to the Sale_2

Liability Related to the Sale of Future Revenues (Tables)	9 Months Ended
	Sep. 30, 2023
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Schedule of changes in liability of sales revenues Agreement Table Text Block	The following table presents the changes in the liability related to the sale of future revenues under the HCRx Agreement for the nine months ended September 30, 2023: (in thousands) Liability related to sale of future revenues as of December 31, 2022 $ 30,236 Accretion of interest expense on liability related to sale of future revenues 3,729 Amortization of debt discount and debt issuance costs 61 Repayment of the liability ( 11 ) Liability related to sale of future revenues as of September 30, 2023 34,015 Less: current portion classified within other accrued liabilities ( 763 ) Long-term liability related to sale of future revenues $ 33,252

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following as of each period end: September 30, December 31, 2023 2022 (in thousands) Leasehold improvements $ 904 $ 875 Lab equipment 15,361 14,797 Machinery and equipment 572 572 Computer equipment and software 1,279 1,149 Furniture and fixtures 1,258 1,297 Construction in progress 239 32 Property and equipment, gross 19,613 18,722 Less: accumulated depreciation ( 14,985 ) ( 12,422 ) Property and equipment, net $ 4,628 $ 6,300

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Summarizes of future termination benefit payments	We recorded the following restructuring charges associated with the reduction in force: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (in thousands) (in thousands) (in thousands) Research and development expense $ — $ 2,710 $ — $ 2,710 General and administrative expense — 3,180 45 3,180 Total restructuring charges $ — $ 5,890 $ 45 $ 5,890
Restructuring of Labiality Activity	The following restructuring liability activity was recorded in connection with the reduction in force for the nine months ended September 30, 2023: (in thousands) Liability balance, December 31, 2022 $ 1,545 Restructuring charges 45 Cash payments ( 1,513 ) Liability balance, September 30, 2023 $ 77

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Summary of RSU Activity	The following is a summary of RSU activity under our 2014 EIP and Inducement Plan: RSUs Shares Weighted Balance as of December 31, 2022 6,708,608 $ 10.61 Granted 5,472,166 $ 3.64 Forfeited ( 1,343,120 ) $ 8.52 Vested ( 2,375,066 ) $ 9.71 Balance as of September 30, 2023 8,462,588 $ 6.69
Summary of Stock Option Activity	The following is a summary of stock option activity under our 2014 EIP and Inducement Plan: Shares Weighted Average Weighted Average Aggregate Intrinsic Balance as of December 31, 2022 10,645,555 $ 16.88 6.4 $ 42 Granted 4,693,897 3.64 — — Exercised — — — — Forfeited or expired ( 2,809,692 ) 16.97 — — Balance as of September 30, 2023 12,529,760 $ 11.90 6.2 $ —
Schedule of Common Stock Reserved for Future Issuance Under Equity Incentive Plans	The following shares of common stock were reserved for future issuance under our equity incentive plans as of September 30, 2023: Total Shares 2014 Equity Incentive Plan 21,564,328 2018 Inducement Plan 4,847,270 2014 Employee Stock Purchase Plan 332,735 Total reserved shares of common stock 26,744,333
Schedule of Stock-based Compensation, Related to Employee and Nonemployee Stock Awards	Stock-based Compensation Expense The following is a summary of stock-based compensation expense for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (in thousands) (in thousands) Research and development $ 6,758 $ 7,986 $ 20,723 $ 24,361 General and administrative 4,385 6,037 14,736 18,114 Total stock-based compensation expense $ 11,143 $ 14,023 $ 35,459 $ 42,475

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	9 Months Ended
	Sep. 30, 2023
Supplemental Balance Sheet Information [Abstract]
Schedule of Inventories	Inventories consisted of the following as of each period end: September 30, December 31, 2023 2022 (in thousands) Raw Materials $ 2,422 $ 1,214 Work-in-process 4,169 372 Total inventories $ 6,591 $ 1,586
Schedule of Property and Equipment	Property and equipment consisted of the following as of each period end: September 30, December 31, 2023 2022 (in thousands) Leasehold improvements $ 904 $ 875 Lab equipment 15,361 14,797 Machinery and equipment 572 572 Computer equipment and software 1,279 1,149 Furniture and fixtures 1,258 1,297 Construction in progress 239 32 Property and equipment, gross 19,613 18,722 Less: accumulated depreciation ( 14,985 ) ( 12,422 ) Property and equipment, net $ 4,628 $ 6,300
Schedule of Other Current Liabilities	Other current liabilities consisted of the following as of each period end: September 30, December 31, 2023 2022 (in thousands) Accrued operating expenses $ 8,299 $ 7,435 Current portion of operating lease liabilities 12,409 12,806 Current portion of finance lease liabilities 887 834 Interest payable 763 — Other accrued liabilities 211 319 Total other current liabilities $ 22,569 $ 21,394

Description of Business (Detail

Description of Business (Detail) - USD ($) $ in Millions	1 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2023	Dec. 31, 2022	Jan. 31, 2022
License Collaboration And Manufacturing Agreements [Line Items]
Entity incorporation state		DE
Entity incorporation date		Aug. 01, 2012
Cash consideration pursuant to asset purchase agreement				$ 100
HCRx Agreement [Member]
License Collaboration And Manufacturing Agreements [Line Items]
Proceeds from sale of future royalties, gross	$ 31		$ 31
Minimum cash repayment		185%
Maximum cash repayment		250%

Net Loss per Common Share - Ant

Net Loss per Common Share - Antidilutive Securities Excluded From Computation of Diluted Net Loss per Common Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	21,217,662	19,135,516	21,217,662	19,135,516
Unvested RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	8,456,088	7,915,826	8,456,088	7,915,826
Vested and Unvested Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	12,288,025	10,954,723	12,288,025	10,954,723
ESPP Share Purchase Rights
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	473,549	264,967	473,549	264,967

Financial Instruments - Summary

Financial Instruments - Summary of Estimated Fair Value and Related Valuation Input Hierarchy of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Total Fair Value	$ 101,169	$ 237,002
Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	101,740	239,069
Total Unrealized Gain	4	7
Total Unrealized Loss	(575)	(2,074)
Total Fair Value	101,169	237,002
Money Market Funds | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	35,230	78,033
Total Unrealized Gain	0	0
Total Unrealized Loss	0	0
Total Fair Value	35,230	78,033
U.S. Treasury Obligations | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	28,318	63,013
Total Unrealized Gain	4	3
Total Unrealized Loss	0	(394)
Total Fair Value	28,322	62,622
Government Agency Obligations | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	1,451	8,086
Total Unrealized Gain	0	0
Total Unrealized Loss	(26)	(48)
Total Fair Value	1,425	8,038
Corporate Debt Obligations | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	34,018	82,598
Total Unrealized Gain	0	4
Total Unrealized Loss	(509)	(1,513)
Total Fair Value	33,509	81,089
Amounts Classified As Cash Equivalents | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	(63,548)	(87,122)
Total Unrealized Gain	(4)	(3)
Total Unrealized Loss	0	0
Total Fair Value	(63,552)	(87,125)
Asset-Backed Securities | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	2,723	6,343
Total Unrealized Gain	0	0
Total Unrealized Loss	(40)	(119)
Total Fair Value	2,683	6,224
Commercial Paper | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost		996
Total Unrealized Gain		0
Total Unrealized Loss		0
Total Fair Value		996
Amounts Classified As Short-Term Investments | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Total Amortized Cost	38,192	151,947
Total Unrealized Gain	0	4
Total Unrealized Loss	(575)	(2,074)
Total Fair Value	$ 37,617	$ 149,877

Financial Instruments - Amortiz

Financial Instruments - Amortized Cost and Fair Value of Available-for-Sale Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized cost
Maturing within one year, Amortized cost	$ 97,367	$ 202,323
Maturing in one to five years, Amortized cost	4,373	36,746
Total available-for-sale securities, Amortized cost	101,740	239,069
Estimated Fair value
Maturing within one year, Estimated fair value	96,863	201,359
Maturing in one to five years, Estimated fair value	4,306	35,643
Total available-for-sale securities, Estimated fair value	$ 101,169	$ 237,002

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financial Instruments Disclosure [Abstract]
Accrued interest receivable	$ 400		$ 400		$ 800
Write off, of accrued interest receivable	$ 0	$ 0	$ 0	$ 0

Financial Instruments - Reconci

Financial Instruments - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Financial Instruments Disclosure [Abstract]
Cash and cash equivalents	$ 64,791	$ 92,942
Restricted cash - short term	146	146
Total cash, cash equivalents and restricted cash	$ 64,937	$ 93,088	$ 66,460	$ 107,478

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 19,613	$ 18,722
Less: accumulated depreciation and amortization	(14,985)	(12,422)
Property and equipment, net	4,628	6,300
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	904	875
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	572	572
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,258	1,297
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 239	$ 32

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment, Net, by Type [Abstract]
Depreciation and amortization expense	$ 3,624	$ 4,398

Out-license Agreements - Schedu

Out-license Agreements - Schedule of Deferred Revenue Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
License Collaboration And Manufacturing Agreements [Line Items]
Deferred revenue - long-term, September 30, 2023	$ 73,929	$ 77,000
Commercialization Revenue [Member]
License Collaboration And Manufacturing Agreements [Line Items]
Deferred revenue, December 31, 2022	85,000
Additions	4,174
Recognized into commercialization revenue	(3,634)
Deferred revenue September 30, 2023	85,540
Less: deferred revenue - current portion	(11,611)
Deferred revenue - long-term, September 30, 2023	$ 73,929

Out-license Agreements - Additi

Out-license Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Oct. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
License Collaboration And Manufacturing Agreements [Line Items]
License and collaboration revenue				$ 118	$ 4,459	$ 624	$ 63,352
Deferred revenue, revenue recognized						$ 3,000
Pierre Fabre Commercialization Agreement
License Collaboration And Manufacturing Agreements [Line Items]
Upfront cash payment received			$ 45,000
Milestone payments	$ 40,000							$ 40,000
Royalty eligible to receive term after first commercial sale			12 years
Years of manufacturing and supplying cost						7 years
Determined upfront payment constituted entire consideration included in transaction price			$ 45,000
Development or sales-based milestone payments earned or received	40,000	$ 30,000
Material rights, term						12 years
License and collaboration revenue				100	200	$ 600	1,600
Pierre Fabre Commercialization Agreement | Maximum [Member]
License Collaboration And Manufacturing Agreements [Line Items]
Aggregate milestone payments entitle to receive upon achieving certain regulatory and commercial milestones			$ 308,000
Bayer Manufacturing Agreement
License Collaboration And Manufacturing Agreements [Line Items]
License and collaboration revenue				0	4,200	0	61,800
Receivable for early contract		$ 4,200			$ 4,200		$ 4,200
Deferred revenue	0			$ 0		$ 0		0
HCRx Agreement [Member]
License Collaboration And Manufacturing Agreements [Line Items]
Proceeds from sale of future royalties, gross	$ 31,000							$ 31,000
Minimum cash repayment						185%
Maximum cash repayment						250%

Liability Related to the Sale_3

Liability Related to the Sale of Future Revenues - Schedule of Liability Related to the Sale of Future Royalties (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Liability related to sale of future revenues	$ 34,015
Accretion of interest expense on liability related to sale of future revenues	3,729	$ 0
Amortization of debt discount and debt issuance costs	61
Repayment of the liability	11
Liability related to sale of future revenues as of September 30, 2023	34,015
Less: current portion classified within other accrued liabilities	(763)
Liability related to the sale of future royalties - long-term	$ 33,252		$ 30,236

Liability Related to the Sale_4

Liability Related to the Sale of Future Revenues (Additional Information) (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Payments for royalties		$ 11
HCRx Agreement [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Minimum cash repayment		185%
Maximum cash repayment		250%
Cash Payment		$ 9,000
Proceeds from sale of future royalties, gross	$ 31,000		$ 31,000
Number Of transaction cost	$ 400
Interest rate of royalties, percentage		15%

Sale of ATOM Facility - Summary

Sale of ATOM Facility - Summary of assets and gain sales (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sale of ATOM Facility	$ 0	$ 94,765

Sale of ATOM Facility - Additio

Sale of ATOM Facility - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jan. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration pursuant to asset purchase agreement					$ 100,000
Cash received on closing of Fujifilm Transaction			$ 0	$ 94,765
Pre-tax gain on sale of business	$ 0	$ 0	$ 0	$ 50,237

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Lease Liabilities Under Operating and Finance Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Leases [Abstract]
Other current liabilities	$ 12,409	$ 12,806
Operating lease liabilities - long-term	48,508	58,064
Other current liabilities	$ 887	$ 834

Leases - Summary of Other Infor

Leases - Summary of Other Information Related to Leases (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract
Financing cash flows for finance leases	$ 732	$ 396

Restructuring (Additional Infor

Restructuring (Additional Information) (Details) $ in Millions	Aug. 08, 2022 USD ($)
Restructuring and Related Activities [Abstract]
Reduction in current workforce	20%
Supplemental Unemployment Benefits, Severance Benefits	$ 6

Restructuring - Summary of futu

Restructuring - Summary of future termination benefit payments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 0	$ 5,890	$ 45	$ 5,890
General and administrative
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	0	3,180	45	3,180
Research and development
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 0	$ 2,710	$ 0	$ 2,710

Restructuring - Restructuring l

Restructuring - Restructuring liability activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Restructuring and Related Activities [Abstract]
Liability balance, Beginning Balance			$ 1,545
Restructuring Charges	$ 0	$ 5,890	45	$ 5,890
Cash payments			(1,513)
Liability balance, Ending Balance	$ 77		$ 77

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
	Apr. 04, 2022	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Contractual obligations due to Bayer, MSK and QIMR		$ 0	$ 0	$ 0
Supply agreement maximum extension term	10 years
Minimum commitments Expense		800	16,100
Accrued termination charges		0	0	0
Liabilities related to indemnification agreements		0	0	0
Minimum purchase commitments accrued		$ 11,000	$ 11,000	$ 9,200

Stockholders' Equity (Deficit_2

Stockholders' Equity (Deficit) - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended	9 Months Ended
	Apr. 25, 2022	Oct. 31, 2023	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2020	May 31, 2020	Jul. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Authorized capital stock			520,000,000	520,000,000	520,000,000
Common stock, par value			$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized			500,000,000	500,000,000	500,000,000
Preferred stock, par value					$ 0.0001
Preferred stock, shares authorized			20,000,000	20,000,000	20,000,000
Preferred stock, shares outstanding			0	0	0
Common stock value remaining to be sold			$ 55.2	$ 55.2
Shares of common stock, reserved for issuance			26,744,333	26,744,333
2014 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock, reserved for issuance			21,564,328	21,564,328
Outstanding options and RSUs			18,014,643,000	18,014,643,000
Aggregate number of awards available for grant to be issued			3,549,685,000	3,549,685,000
Inducement Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock, reserved for issuance			4,847,270	4,847,270
Outstanding options and RSUs			2,977,705	2,977,705
Aggregate number of awards available for grant to be issued			1,869,565	1,869,565
Additional shares of common stock, reserved for issuance						1,500,000
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense			$ 49.7	$ 49.7
Unrecognized stock-based compensation weighted average recognition period				2 years 2 months 12 days
Vested and Unvested Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation weighted average recognition period				2 years 1 month 6 days
Unrecognized stock-based compensation			$ 23.4	$ 23.4
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of employees purchase price of common stock				100%
Minimum [Member] | Restricted Stock Units (RSUs) | From Date Of Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, vesting period				3 years
Minimum [Member] | Employees And Non Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, vesting period				3 years
Stock option granted description terms				the exercise price of an option granted to a 10% shareholder cannot be less than 110% of the estimated fair value of the shares on the date of grant. Options granted generally vest over three or four years and expire in seven to ten years.
Share based compensation award expiration period				7 years
Maximum [Member] | Restricted Stock Units (RSUs) | From Date Of Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, vesting period				4 years
Maximum [Member] | Employees And Non Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, vesting period				4 years
Share based compensation award expiration period				10 years
Underwritten Public Offering | 2019 Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise of pre-funded warrants, shares			361,260	361,260
Warrants outstanding			2,527,266	2,527,266
Underwritten Public Offering | Warrant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of warrants issued									2,945,026
Number of securities called by each warrant									1
Warrants, exercise price									$ 0.0001
Warrants, term	7 years
Maximum ownership Percentage				9.99%
Underwritten Public Offering | Warrant | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Prior notice period	61 days
Underwritten Public Offering | Warrant | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum ownership Percentage				19.99%
Underwritten Public Offering | Warrant | December 2020 Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of warrants issued							2,040,816
Exercise of pre-funded warrants, shares				656,107
Warrants outstanding			1,384,709	1,384,709
Underwritten Public Offering | Warrant | May 2020 Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of warrants issued								2,866,961
Exercise of pre-funded warrants, shares				1,898,578
Warrants outstanding			968,383	968,383
At The Market Offering | Cowen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock aggregate offering price		$ 100	$ 100	$ 100
Percentage of commission to be paid on gross sales proceeds of common stock sold		3%		3%
Common stock, shares issued				147,930
Common stock average price				$ 4.64
Proceeds from sale of common stock, gross				$ 0.7
Proceeds from sale of common stock, net				$ 0.6

Stockholders' Equity (Deficit_3

Stockholders' Equity (Deficit) - Summary of RSU Activity (Detail) - Unvested RSUs	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Balance as of December 31, 2022 | shares	6,708,608
Shares, Granted | shares	5,472,166
Shares, Forfeited | shares	(1,343,120)
Shares, Vested | shares	(2,375,066)
Balance as of September 30, 2023 | shares	8,462,588
Balance as of December 31, 2022 | $ / shares	$ 10.61
Weighted Average Grant Date Fair Value, Granted | $ / shares	3.64
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	8.52
Weighted Average Grant Date Fair Value, Vested | $ / shares	9.71
Balance as of September 30, 2023 | $ / shares	$ 6.69

Stockholders' Equity (Deficit_4

Stockholders' Equity (Deficit) - Summary of Stock Option Activity (Detail) - 2014 EIP and Inducement Plan - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Shares, beginning balance	10,645,555
Granted, Shares	4,693,897
Exercised, Shares	0
Forfeited or expired, Shares	(2,809,692)
Outstanding, Shares, ending balance	12,529,760	10,645,555
Outstanding, Weighted Average Exercise Price, beginning balance	$ 16.88
Granted, Weighted Average Exercise Price	3.64
Exercised, Weighted Average Exercise Price	0
Forfeited or expired, Weighted Average Exercise price	16.97
Outstanding, Weighted Average Exercise Price, ending balance	$ 11.9	$ 16.88
Outstanding, Weighted Average Remaining Contractual Term	6 years 2 months 12 days	6 years 4 months 24 days
Aggregate intrinsic value	$ 0	$ 42

Stockholders' Equity (Deficit_5

Stockholders' Equity (Deficit) - Schedule of Common Stock Reserved for Future Issuance Under Equity Incentive Plans (Detail)	Sep. 30, 2023 shares
Class Of Stock [Line Items]
Total reserved shares of common stock	26,744,333
2014 Equity Incentive Plan
Class Of Stock [Line Items]
Total reserved shares of common stock	21,564,328
2018 Inducement Plan
Class Of Stock [Line Items]
Total reserved shares of common stock	4,847,270
2014 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Total reserved shares of common stock	332,735

Stockholders' Equity (Deficit_6

Stockholders' Equity (Deficit) - Schedule of Stock-based Compensation Related to All Employee And Non-employee Stock Awards (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 11,143	$ 14,023	$ 35,459	$ 42,475
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	6,758	7,986	20,723	24,361
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 4,385	$ 6,037	$ 14,736	$ 18,114

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Supplemental Balance Sheet Information [Abstract]
Depreciation expense	$ 0.9	$ 1.1	$ 2.8	$ 3.8

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Schedule of Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Supplemental Balance Sheet Information [Abstract]
Raw Materials	$ 2,422	$ 1,214
Work-in-process	4,169	372
Total inventories	$ 6,591	$ 1,586

Supplemental Balance Sheet In_5

Supplemental Balance Sheet Information - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	$ 19,613	$ 18,722
Less: accumulated depreciation and amortization	(14,985)	(12,422)
Property and equipment, net	4,628	6,300
Leasehold Improvements
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	904	875
Lab equipment
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	15,361	14,797
Machinery and Equipment
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	572	572
Computer equipment and software
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	1,279	1,149
Furniture and Fixtures
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	1,258	1,297
Construction in Progress
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	$ 239	$ 32

Supplemental Balance Sheet In_6

Supplemental Balance Sheet Information - Schedule of Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Supplemental Balance Sheet Information [Abstract]
Accrued operating expenses	$ 8,299	$ 7,435
Current portion of operating lease liabilities	12,409	12,806
Current portion of finance lease liabilities	887	834
Interest payable	763	0
Other accrued liabilities	211	319
Total other current liabilities	$ 22,569	$ 21,394

Subsequent Events (Additional I

Subsequent Events (Additional Information) (Details) - USD ($) $ in Millions	Nov. 01, 2023	Aug. 08, 2022
Subsequent Event [Line Items]
Reduction in current workforce		20%
Supplemental Unemployment Benefits, Severance Benefits		$ 6
Subsequent Event [Member]
Subsequent Event [Line Items]
Milestone payments	$ 620
Subsequent Event, Description	Pursuant to the A&R Commercialization Agreement, Pierre Fabre will pay us an additional upfront cash payment of $20.0 million for the expanded exclusive license grant. We will also be entitled to receive an aggregate of up to $620.0 million in additional milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Additional Territory. In addition, we will be eligible to receive double-digit tiered royalties as a percentage of net sales of tab-cel (Ebvallo) in the Territory until the later of 12 years after the first commercial sale in such country, the expiration of specified patent rights in such country, or the expiration of all regulatory exclusivity for such Product in such country. Royalty payments may be reduced in certain specified customary circumstances. Royalties and milestones from the commercialization of Ebvallo in the Initial Territory remain subject to the HCRx Agreement.
Subsequent Event [Member] | Employee Severance [Member]
Subsequent Event [Line Items]
Reduction in current workforce	30%
Supplemental Unemployment Benefits, Severance Benefits	$ 7
Subsequent Event, Description	On November 1, 2023, we announced a reduction in force that will reduce our current workforce by approximately 30%. We expect to recognize approximately $7.0 million in total for severance and related benefits for employees laid off under the reduction in force. These charges are primarily one-time termination benefits and are all cash charges. We may also incur other charges or cash expenditures not currently contemplated due to events that may occur as a result of, or associated with, the workforce reduction.
Subsequent Event [Member] | Up-front Payment Arrangement [Member]
Subsequent Event [Line Items]
Upfront cash payment received	$ 20