Lyell Immunopharma (LYEL) 10-Q 8 Aug 23 2023 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2023	Aug. 03, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
Document Transition Report	false
Entity File Number	001-40502
Entity Registrant Name	Lyell Immunopharma, Inc.
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	83-1300510
Entity Address Line	201 Haskins Way
Entity Address City Or Town	South San Francisco
Entity Address State Or Province	CA
Entity Address Postal Zip Code	94080
City Area Code	650
Local Phone Number	695-0677
Security12b Title	Common Stock, $0.0001 par value per share
Trading Symbol	LYEL
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		251,026,997
Entity Central Index Key	0001806952
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 224,372	$ 123,554
Marketable securities	371,376	516,598
Prepaid expenses and other current assets	10,662	11,143
Total current assets	606,410	651,295
Restricted cash	282	280
Marketable securities, non-current	36,952	70,117
Other investments	32,001	44,924
Property and equipment, net	113,677	123,023
Operating lease right-of-use assets	41,512	43,242
Other non-current assets	4,520	4,680
Total assets	835,354	937,561
Current liabilities:
Accounts payable	5,805	3,917
Accrued liabilities and other current liabilities	24,832	28,755
Success payment liabilities	3,753	4,356
Total current liabilities	34,390	37,028
Operating lease liabilities, non-current	60,221	63,168
Other non-current liabilities	3,888	4,113
Total liabilities	98,499	104,309
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000 shares authorized at June 30, 2023 and December 31, 2022; no shares issued and outstanding at June 30, 2023 and December 31, 2022	0	0
Common stock, $0.0001 par value; 500,000 shares authorized at June 30, 2023 and December 31, 2022; 251,027 and 249,567 shares issued and outstanding at June 30, 2023 and December 31, 2022, respectively	25	25
Additional paid-in capital	1,637,538	1,608,306
Accumulated other comprehensive loss	(2,379)	(7,599)
Accumulated deficit	(898,329)	(767,480)
Total stockholders’ equity	736,855	833,252
Total liabilities and stockholders’ equity	$ 835,354	$ 937,561

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock authorized (in shares)	10,000,000	10,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock authorized (in shares)	500,000,000	500,000,000
Common stock issued (in shares)	251,027,000	249,567,000
Common stock outstanding (in shares)	251,026,997	249,567,343

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Revenue	[1]	$ 27	$ 35,741	$ 92	$ 36,294
Operating expenses:
Research and development		47,471	43,719	92,101	79,549
General and administrative		19,030	30,454	38,309	64,875
Other operating income, net		(569)	(1,171)	(1,857)	(2,293)
Total operating expenses		65,932	73,002	128,553	142,131
Loss from operations		(65,905)	(37,261)	(128,461)	(105,837)
Interest income, net		5,264	952	9,761	1,349
Other (expense) income, net		(326)	(14)	774	21
Impairment of other investments		(2,923)	0	(12,923)	0
Total other income (loss), net		2,015	938	(2,388)	1,370
Net loss		(63,890)	(36,323)	(130,849)	(104,467)
Comprehensive loss:
Net unrealized gain (loss) on marketable securities		1,500	(1,751)	5,220	(6,728)
Comprehensive loss		$ (62,390)	$ (38,074)	$ (125,629)	$ (111,195)
Net loss per common share, basic (in dollars per share)		$ (0.26)	$ (0.15)	$ (0.52)	$ (0.43)
Net loss per common share, diluted (in dollars per share)		$ (0.26)	$ (0.15)	$ (0.52)	$ (0.43)
Weighted-average shares used to compute net loss per common share, basic (in shares)		250,204	246,312	249,899	245,251
Weighted-average shares used to compute net loss per common share, diluted (in shares)		250,204	246,312	249,899	245,251
[1](1)    None of the revenue for the three and six months ended June 30, 2023 was from a related-party. Substantially all of the revenue for the three and six months ended June 30, 2022 was from a related-party.

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
		Jun. 30, 2023	Jun. 30, 2023
Revenue	[1]	$ 27	$ 92
Related Party
Revenue		$ 0	$ 0
[1](1)    None of the revenue for the three and six months ended June 30, 2023 was from a related-party. Substantially all of the revenue for the three and six months ended June 30, 2022 was from a related-party.

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2021		242,738,000
Beginning balance at Dec. 31, 2021	$ 929,787	$ 24	$ 1,515,748	$ (1,623)	$ (584,362)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		2,138,000
Issuance of common stock upon exercise of stock options	4,125	$ 1	4,124
Issuance of common stock under employee stock purchase plan (in shares)		284,000
Issuance of common stock under employee stock purchase plan	887		887
Stock-based compensation (in shares)		1,950,000
Stock-based compensation	44,438		44,438
Other comprehensive income (loss)	(6,728)			(6,728)
Net loss	(104,467)				(104,467)
Ending balance (in shares) at Jun. 30, 2022		247,110,000
Ending balance at Jun. 30, 2022	868,042	$ 25	1,565,197	(8,351)	(688,829)
Beginning balance (in shares) at Mar. 31, 2022		245,423,000
Beginning balance at Mar. 31, 2022	881,249	$ 25	1,540,330	(6,600)	(652,506)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		428,000
Issuance of common stock upon exercise of stock options	1,570		1,570
Issuance of common stock under employee stock purchase plan (in shares)		284,000
Issuance of common stock under employee stock purchase plan	887		887
Stock-based compensation (in shares)		975,000
Stock-based compensation	22,410		22,410
Other comprehensive income (loss)	(1,751)			(1,751)
Net loss	(36,323)				(36,323)
Ending balance (in shares) at Jun. 30, 2022		247,110,000
Ending balance at Jun. 30, 2022	$ 868,042	$ 25	1,565,197	(8,351)	(688,829)
Beginning balance (in shares) at Dec. 31, 2022	249,567,343	249,567,000
Beginning balance at Dec. 31, 2022	$ 833,252	$ 25	1,608,306	(7,599)	(767,480)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	832,840	833,000
Issuance of common stock upon exercise of stock options	$ 83		83
Issuance of common stock under employee stock purchase plan (in shares)		543,000
Issuance of common stock under employee stock purchase plan	1,163		1,163
Issuance of common stock in connection with restricted stock units, net of tax (in shares)		84,000
Issuance of common stock in connection with restricted stock units, net of tax	(119)		(119)
Stock-based compensation	28,105		28,105
Other comprehensive income (loss)	5,220			5,220
Net loss	$ (130,849)				(130,849)
Ending balance (in shares) at Jun. 30, 2023	251,026,997	251,027,000
Ending balance at Jun. 30, 2023	$ 736,855	$ 25	1,637,538	(2,379)	(898,329)
Beginning balance (in shares) at Mar. 31, 2023		249,609,000
Beginning balance at Mar. 31, 2023	783,826	$ 25	1,622,119	(3,879)	(834,439)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		833,000
Issuance of common stock upon exercise of stock options	83		83
Issuance of common stock under employee stock purchase plan (in shares)		543,000
Issuance of common stock under employee stock purchase plan	1,163		1,163
Issuance of common stock in connection with restricted stock units, net of tax (in shares)		42,000
Issuance of common stock in connection with restricted stock units, net of tax	(50)		(50)
Stock-based compensation	14,223		14,223
Other comprehensive income (loss)	1,500			1,500
Net loss	$ (63,890)				(63,890)
Ending balance (in shares) at Jun. 30, 2023	251,026,997	251,027,000
Ending balance at Jun. 30, 2023	$ 736,855	$ 25	$ 1,637,538	$ (2,379)	$ (898,329)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (130,849)	$ (104,467)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	28,105	44,438
Impairment of other investments	12,923	0
Depreciation and amortization expense	10,089	8,358
Net amortization and accretion on marketable securities	(3,925)	706
Non-cash lease income	(816)	(655)
Change in fair value of success payment liabilities	(603)	(264)
Loss on property and equipment disposals	430	84
Change in fair value of equity warrant	0	(14)
Changes in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	641	9
Accounts payable	2,449	1,170
Accrued liabilities and other current liabilities	(3,592)	(7,159)
Deferred revenue	0	(36,300)
Operating lease liabilities, non-current	0	2,135
Other non-current liabilities	(225)	(226)
Net cash used in operating activities	(85,373)	(92,185)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(2,466)	(16,903)
Purchases of marketable securities	(141,815)	(185,855)
Sales and maturities of marketable securities	329,347	201,655
Net cash provided by (used in) investing activities	185,066	(1,103)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from exercise of stock options	83	4,125
Proceeds from employee stock purchase plan	1,163	887
Taxes paid related to net share settlement of equity awards	(119)	0
Net cash provided by financing activities	1,127	5,012
Net increase (decrease) in cash, cash equivalents and restricted cash	100,820	(88,276)
Cash, cash equivalents and restricted cash at beginning of period	123,834	294,294
Cash, cash equivalents and restricted cash at end of period	224,654	206,018
Represented by:
Cash and cash equivalents	224,372	205,739
Restricted cash	282	279
Total	224,654	206,018
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for amounts included in the measurement of lease liabilities	5,215	5,399
Cash received for amounts related to tenant improvement allowances	0	2,042
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued liabilities	$ 33	$ 3,553

Organization

Organization	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Lyell Immunopharma, Inc. (the “Company”) was incorporated in Delaware in June 2018. The Company is a clinical-stage cell therapy company advancing a pipeline of product candidates for patients with solid tumors utilizing its proprietary ex vivo

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiary. All significant intercompany transactions and balances have been eliminated in consolidation. The Condensed Consolidated Balance Sheet as of December 31, 2022 included herein was derived from the audited consolidated financial statements as of that date. Certain information and footnote disclosures typically included in the Company’s audited consolidated financial statements have been condensed or omitted. The accompanying unaudited Condensed Consolidated Financial Statements have been prepared on the same basis as the annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented, but are not necessarily indicative of results to be expected for any future annual or interim period. These unaudited Condensed Consolidated Financial Statements should be read in conjunction with the Company’s audited financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022. Liquidity and Management’s Plan The Company discovers and develops product candidates that involve experimental technologies. The product candidates may require several years and substantial expenditures to complete and ultimately may be unsuccessful. The Company plans to finance operations with available cash resources or from the issuance of equity or debt securities. The Company believes that its available cash, cash equivalents and marketable securities as of June 30, 2023 will be adequate to fund its operations at least through the next 12 months from the date these unaudited Condensed Consolidated Financial Statements are issued. Use of Estimates The preparation of the Company’s Condensed Consolidated Financial Statements in conformity with GAAP requires management to make judgments, estimates and assumptions that affect reported amounts and related disclosures. Specific accounts that require management estimates include, but are not limited to, stock-based compensation, valuation of success payments, valuation of other investments, revenue recognition and accrued expenses. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates. In June 2022, the Company recorded an adjustment to revenue related to a change in estimate in connection with the Collaboration and License Agreement, entered into in 2019 and amended in June 2020 and December 2021 (“GSK Agreement”) with GlaxoSmithKline Intellectual Property (No. 5) Limited and Glaxo Group Limited (together, “GSK”). The Company and GSK mutually agreed to conclude research activities on an undisclosed target for hematological cancers in June 2022. As a result, the Company decreased the related estimated project costs, which resulted in an increase in the measure of proportional cumulative performance. This adjustment increased revenue by $35.3 million, decreased net loss by $35.3 million and resulted in a $0.14 reduction in the Company’s basic and diluted net loss per common share for the three and six months ended June 30, 2022. Concentrations of Credit Risk and Off-balance Sheet Risk The Company maintains its cash, cash equivalents and restricted cash with high quality, accredited financial institutions. Restricted cash is cash held in bank accounts and is used as collateral associated with the Company’s corporate credit card program. Cash, cash equivalents and restricted cash amounts, at times, may exceed federally insured limits. The Company also makes short-term investments in money market funds, U.S. Treasury securities, U.S. government agency securities and corporate debt securities, which can be subject to certain credit risk. However, the Company mitigates the risks by investing in high‑grade instruments, limiting exposure to any one issuer or type of investment and monitoring the ongoing creditworthiness of the financial institutions and issuers. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to significant risk on these funds. The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements. Significant Accounting Policies There have been no material changes to the significant accounting policies from the Annual Report on Form 10-K for the year ended December 31, 2022. Recently Adopted Accounting Pronouncements None.

License, Collaboration, and Suc

License, Collaboration, and Success Payment Agreements	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License, Collaboration, and Success Payment Agreements	icense, Collaboration and Success Payment Agreements Fred Hutch License Agreement - In 2018, the Company entered into a license agreement with Fred Hutchinson Cancer Center (“Fred Hutch”) that grants the Company a worldwide, sublicensable license under certain patent rights (exclusive) and certain technology (non-exclusive) to research, develop and commercialize products and processes for all fields of use utilizing chimeric antigen receptors (“CARs”) and/or T-cell receptors (“TCRs”), subject to certain exceptions. The Company is required to pay Fred Hutch annual license maintenance payments of $50,000 on the second anniversary of the effective date, and each anniversary of the effective date thereafter until the first commercial sale of a licensed product. Collaboration - In 2018, the Company entered into a research and collaboration agreement with Fred Hutch (“Fred Hutch Collaboration Agreement”) focused on research and development of cancer immunotherapy products. The Company funded aggregate research performed by Fred Hutch of $12.0 million under the Fred Hutch Collaboration Agreement, with the research conducted in accordance with a research plan and budget approved by the parties. The Fred Hutch Collaboration Agreement has a six-year term. The Company incurred $0.1 million and $0.5 million in expense in connection with the Fred Hutch Collaboration Agreement for the three months ended June 30, 2023 and 2022, respectively, and $0.4 million and $1.0 million for the six months ended June 30, 2023 and 2022, respectively. Success Payments - In 2018, the Company granted Fred Hutch rights to certain success payments, pursuant to the terms of the Fred Hutch Collaboration Agreement. The potential payments for the Fred Hutch success payments are based on multiples of increased value ranging from 10x to 50x based on a comparison of the per share fair market value of the Company’s common stock relative to the original $1.83 per share issuance price of the Company’s Series A convertible preferred stock, which converted into an equal number of shares of the Company’s common stock in connection with the Company’s initial public offering (“IPO”). The aggregate success payments to Fred Hutch are not to exceed $200.0 million, which would only occur upon a 50x increase in value. Each threshold is associated with a success payment, ascending from $10.0 million at $18.29 per share to $200.0 million at $91.44 per share, payable if such threshold is reached during the measurement period. Any previous success payments made are credited against the success payment owed as of any valuation date, such that Fred Hutch does not receive multiple success payments in connection with the same threshold. The term of the success payment agreement ends on the earlier to occur of (i) the nine-year anniversary of the date of the agreement and (ii) a change in control transaction. The following table summarizes the aggregate potential success payments, which are payable to Fred Hutch in cash or cash equivalents, or at the Company’s discretion, publicly-tradeable shares of the Company’s common stock: Multiple of initial equity value at issuance 10x 20x 30x 40x 50x Per share common stock price required for payment $ 18.29 $ 36.58 $ 54.86 $ 73.15 $ 91.44 Aggregate success payment(s) (in millions) $ 10 $ 40 $ 90 $ 140 $ 200 The success payments will be owed if the per share fair value of the Company’s common stock on the contractually specified valuation measurement dates during the term of the success payment agreement equals or exceeds the above outlined multiples. The valuation measurement dates are triggered by the following events: the one-year anniversary of the Company’s IPO and each two-year anniversary of the Company’s IPO thereafter, the closing of a change in control transaction and the last day of the term of the success payment agreement, unless the term has ended due to the closing of a change of control transaction. As of June 30, 2023, no success payments have been incurred as the per share fair value of the Company’s common stock was below the price required for payment. The success payment liability was estimated at fair value at inception and at each subsequent reporting period and the associated expense was accreted over the service period of the success payment obligations as research and development expense through 2022. As of December 31, 2022, the Company’s associated success payment liability was fully accreted to fair value as Fred Hutch had provided the requisite service obligation to earn the potential success payment consideration under the continued collaboration. For the three and six months ended June 30, 2023 and future periods, the change in the Fred Hutch success payment liability fair value is recognized in other (expense) income, net, as the requisite service obligation had been met. The success payment liability was $1.9 million and $2.5 million as of June 30, 2023 and December 31, 2022, respectively. With respect to the Fred Hutch Collaboration Agreement success payment obligations, the Company recognized expense of $0.5 million and $2.2 million for the three months ended June 30, 2023 and 2022, respectively, and gains of $0.6 million for both the six months ended June 30, 2023 and 2022. Stanford License Agreement - In 2019, the Company entered into a license agreement with The Board of Trustees of the Leland Stanford Junior University (“Stanford”) to license specified patent rights. The Company is required to pay Stanford annual license maintenance payments of $50,000 on the second anniversary of the effective date, and each anniversary of the effective date thereafter until the date of the first commercial sale of a licensed product. Milestone payments to Stanford of up to a maximum of $3.7 million per target are payable upon achievement of certain specified clinical and regulatory milestones. The Company is also obligated to pay Stanford $2.5 million collectively for all licensed products upon the achievement of a certain commercial milestone. Additionally, low single‑digit tiered royalties based on annual net sales of the licensed products are payable to Stanford. Collaboration Agreement - In October 2020, the Company entered into a research and collaboration agreement with Stanford (“Stanford Collaboration Agreement”), focused on research and development of cellular immunotherapy products. The Stanford Collaboration Agreement has a four-year term. The Company is committed to fund aggregate research performed by Stanford of $12.0 million under the Stanford Collaboration Agreement, and the research will be conducted in accordance with a research plan and budget approved by the parties. The Company incurred $0.7 million and $0.8 million in expense in connection with the Stanford Collaboration Agreement for the three months ended June 30, 2023 and 2022, respectively, and $1.5 million for both the six months ended June 30, 2023 and 2022. Success Payments - In October 2020, the Company granted Stanford rights to certain success payments, pursuant to the terms of the Stanford Collaboration Agreement. The potential payments for the Stanford Collaboration Agreement success payments are based on multiples of increased value ranging from 10x to 50x based on a comparison of the per share fair market value of the Company’s common stock relative to the original $1.83 issuance price of the Company’s Series A convertible preferred stock, which converted into an equal number of shares of the Company’s common stock in connection with the Company’s IPO. The aggregate success payments to Stanford are not to exceed $200.0 million, which would only occur upon a 50x increase in value. Each threshold is associated with a success payment, ascending from $10.0 million at $18.29 per share to $200.0 million at $91.44 per share, payable if such threshold is reached during the measurement period. Any previous success payments made are credited against the success payment owed as of any valuation date, so that Stanford does not receive multiple success payments in connection with the same threshold. The term of each success payment agreement ends on the earlier to occur of (i) the nine-year anniversary of the date of the agreement and (ii) a change in control transaction. The following table summarizes the aggregate potential success payments, which are payable to Stanford in cash or cash equivalents, or at the Company’s discretion, publicly-tradeable shares of the Company’s common stock: Multiple of initial equity value at issuance 10x 20x 30x 40x 50x Per share common stock price required for payment $ 18.29 $ 36.58 $ 54.86 $ 73.15 $ 91.44 Aggregate success payment(s) (in millions) $ 10 $ 40 $ 90 $ 140 $ 200 The success payments will be owed if the per share fair value of the Company’s common stock on the contractually specified valuation measurement dates during the term of the success payment agreement equals or exceeds the above outlined multiples. The valuation measurement dates are triggered by the following events: the one-year anniversary of the Company’s IPO and each two-year anniversary of the Company’s IPO thereafter, the closing of a change in control transaction and the last day of the term of the success payment agreement, unless the term has ended due to the closing of a change of control transaction. As of June 30, 2023, no success payments have been incurred as the per share fair value of the Company’s common stock was below the price required for payment. The estimated fair values of the success payments to Stanford as of June 30, 2023 and December 31, 2022 were $2.7 million and $3.3 million, respectively. The success payment liability is estimated at the fair value at inception and at each subsequent reporting period and the expense is accreted over the service period of the Stanford Collaboration Agreement as research and development expense. The success payment liability was $1.9 million as of both June 30, 2023 and December 31, 2022. With respect to the Stanford Collaboration Agreement success payment obligations, the Company recognized expense of $0.6 million and $1.4 million for the three months ended June 30, 2023 and 2022, respectively, and expense of approximately zero and $0.4 million for the six months ended June 30, 2023 and 2022, respectively. GSK In 2019, the Company entered into the GSK Agreement with GSK for potential T‑cell therapies that apply the Company’s platform technologies and cell therapy innovations with TCRs or CARs under distinct collaboration programs. The GSK Agreement defined two initial collaboration targets, LYL331 and LYL132, and allowed GSK to nominate seven additional targets through July 2024, though no additional targets were nominated over the life of the GSK Agreement. The Company was expected to perform research and development services for each selected target up until a defined point (the “GSK Option Point”), at which time GSK would decide whether or not to exercise an option to obtain a license from the Company (“License Option”) and take over the future development and commercialization. In April 2021, GSK exercised the License Option on LYL331 (NY-ESO-1 TCR with c-Jun) and assumed sole responsibility for future development and commercialization of the program at its own cost and expense. The investigational new drug (“IND”) application for LYL132 was cleared in January 2022, though no patients were treated, and the IND for LYL331 was not submitted to the U.S. Food and Drug Administration. GSK terminated the GSK Agreement effective December 24, 2022, and Lyell has also discontinued any further work on these programs. There are no future performance obligations associated with the GSK Agreement. The Company received a non-refundable upfront payment of $45.0 million under the GSK Agreement. In connection with the GSK Agreement, in May 2019, the Company also entered into a stock purchase agreement with GSK, pursuant to which the Company agreed to sell 30,253,189 shares of Series AA convertible preferred stock at a price of $6.78 per share, which was above the issuance date estimated fair value of $4.84 per share. The difference between the per share values resulted in $58.6 million additional deemed consideration, bringing the total upfront consideration of the GSK Agreement to $103.6 million. The GSK Agreement was deemed to be within the scope of Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers , because GSK engaged the Company to initially provide research and development services, which were outputs of its ongoing activities, in exchange for consideration. In June 2022, the Company recorded an adjustment to revenue related to a change in estimate in connection with the GSK Agreement due to GSK and the Company mutually agreeing to conclude research activities on an undisclosed target for hematological cancers. The change in estimate decreased the related estimated project costs, which resulted in an increase in the measure of proportional cumulative performance. This adjustment increased revenue by $35.3 million, decreased net loss by $35.3 million and resulted in a $0.14 reduction in the Company’s basic and diluted net loss per common share for the three and six months ended June 30, 2022. The Company recognized revenue related to the research and development services related to the two initial targets of zero and $35.7 million for the three months ended June 30, 2023 and 2022, respectively, and zero and $36.3 million for the six months ended June 30, 2023 and 2022, respectively. The Company had no deferred revenue related to the GSK Agreement as of both June 30, 2023 and December 31, 2022. As of June 30, 2023 and December 31, 2022, there were no contract assets or contract liabilities related to the license contract. PACT In June 2020, the Company entered into a commitment agreement (“PACT Commitment Agreement”) with PACT Pharma, Inc. (“PACT”) to jointly develop and test a next generation personalized anti-cancer T-cell therapy against solid tumors. The Company paid PACT an upfront non-refundable payment of $50.0 million upon execution of the PACT Commitment Agreement. In November 2020, the parties agreed to suspend research and development activity under the PACT Commitment Agreement, and neither party would be required to conduct any further work under the development plan (including manufacturing development) nor incur any financial obligations (including milestone payments) that might otherwise arise, for as long as the parties continued to negotiate in good faith to resolve the issues that had arisen between them relating to the PACT Commitment Agreement. In June 2020 in connection with the entry into the PACT Commitment Agreement, the Company also entered into a stock purchase agreement with PACT (“PACT SPA”), pursuant to which the Company purchased 17,806,901 shares of PACT Series C-1 convertible preferred stock at a purchase price of $2.81 per share. As of the purchase date, the estimated fair value of the Series C-1 convertible preferred stock was $2.05 per share, and the difference between the estimated fair value of the preferred stock as of the purchase date and the purchase price of $13.6 million was deemed to be additional consideration for the PACT Commitment Agreement and recognized as research and development expense. As a result, the total upfront consideration paid in connection with the PACT Commitment Agreement was $63.6 million and was included in research and development expenses. The remaining $36.4 million associated with the PACT Series C-1 convertible preferred stock was recorded in other investments. In the fourth quarter of 2021, the Company fully impaired the remaining balance of $36.4 million. In February 2021, the Company filed a demand for arbitration seeking, among other things, rescission of the PACT Commitment Agreement and the PACT SPA and recovery of the consideration paid thereunder. Arbitration hearings occurred in March and April 2022. On October 1, 2022, the Company entered into a settlement agreement with PACT, pursuant to which the parties agreed to resolve their outstanding legal dispute. In connection with the settlement agreement, the parties also entered into a stock purchase agreement, pursuant to which PACT issued shares of PACT’s Series D convertible preferred stock to the Company in exchange for the Company’s tender of its PACT Series C-1 convertible preferred stock and resolution of the arbitration. The issuance of PACT’s Series D convertible preferred stock, which are non-voting, have limited conversion rights and carry no right to appoint directors, resulted in the Company’s ownership increasing to approximately 80% of PACT’s fully diluted shares outstanding. The settlement agreement also included the termination of the PACT Commitment Agreement. The Company recorded a gain of $2.9 million in October 2022 for the estimated fair value of the PACT Series D convertible preferred stock received as part of the settlement agreement. The PACT Series D convertible preferred stock was recorded at its estimated fair value as of the settlement date and was included in other investments in the Company’s Condensed Consolidated Balance Sheets. In connection with the preparation of the financial statements for the three and six months ended June 30, 2023, the Company performed a qualitative assessment of potential indicators of impairment, resulting in the impairment of the $2.9 million PACT Series D convertible preferred stock investment. See Note 5, Other Investments , for additional details regarding the PACT investment impairment.

Cash Equivalents and Marketable

Cash Equivalents and Marketable Securities	6 Months Ended
	Jun. 30, 2023
Cash and Cash Equivalents [Abstract]
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities The fair value and amortized cost of cash equivalents and marketable securities by major security type are as follows (in thousands): June 30, 2023 Amortized Cost Gross Gross Unrealized Losses Fair Value Money market funds $ 116,970 $ — $ — $ 116,970 U.S. Treasury securities 292,610 31 (1,352) 291,289 U.S. government agency securities 95,331 — (820) 94,511 Corporate debt securities 106,706 — (238) 106,468 Total cash equivalents and marketable securities $ 611,617 $ 31 $ (2,410) $ 609,238 Classified as: Fair Value Cash equivalents $ 200,910 Marketable securities 371,376 Marketable securities, non-current 36,952 Total cash equivalents and marketable securities $ 609,238 December 31, 2022 Amortized Cost Gross Gross Unrealized Losses Fair Value Money market funds $ 67,970 $ — $ — $ 67,970 U.S. Treasury securities 277,056 — (5,257) 271,799 U.S. government agency securities 135,460 1 (1,416) 134,045 Corporate debt securities 221,608 3 (930) 220,681 Total cash equivalents and marketable securities $ 702,094 $ 4 $ (7,603) $ 694,495 Classified as: Fair Value Cash equivalents $ 107,780 Marketable securities 516,598 Marketable securities, non-current 70,117 Total cash equivalents and marketable securities $ 694,495 The fair values of securities held by the Company in an unrealized loss position for less than 12 months were $261.7 million and $287.8 million as of June 30, 2023 and December 31, 2022, respectively. The fair values of securities held by the Company in an unrealized loss position for greater than 12 months were $101.2 million and $278.7 million as of June 30, 2023 and December 31, 2022, respectively. As of June 30, 2023 and December 31, 2022, all of the Company’s marketable securities had a maturity date of two years or less, were available for use and were classified as available‑for‑sale. The Company does not intend to sell these securities nor does the Company believe that it will be required to sell these securities before recovery of their amortized cost basis. The Company determined that there was no material change in the credit risk of the above investments as of both June 30, 2023 and December 31, 2022. As such, an allowance for credit losses has not been recognized. Gross realized gains and losses were de minimis for the three and six months ended June 30, 2023 and 2022 and as a result, amounts reclassified out of accumulated other comprehensive loss for the three and six months ended June 30, 2023 and 2022 were also de minimis . See Note 6, Fair Value Measurements, for additional information regarding cash equivalents and marketable securities.

Other Investments

Other Investments	6 Months Ended
	Jun. 30, 2023
Investments, All Other Investments [Abstract]
Other Investments	Other Investments From time to time, the Company makes minority ownership strategic investments. As of June 30, 2023 and December 31, 2022, the aggregate carrying amounts of the Company’s strategic investments in non-publicly traded companies were $32.0 million and $44.9 million, respectively. These investments are measured at initial cost, minus impairment, if any, and plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Cumulative impairments of strategic investments in equity investments without readily determinable fair values still held as of June 30, 2023 and December 31, 2022 were $17.9 million and $5.0 million, respectively. In October 2022, the Company received non-voting preferred stock pursuant to the settlement agreement with PACT (See Note 3, License, Collaboration and Success Payment Agreements ). The Company determined that PACT is a variable interest entity as PACT does not have sufficient equity at risk. The Company evaluated whether it was the primary beneficiary of PACT, including the Company’s ongoing rights and responsibilities, to assess whether the Company has the power to direct the activities of PACT. The Company’s only involvement in PACT is its PACT Series D convertible preferred stock investment, which are non-voting, have limited conversion rights and carry no right to appoint directors. Based on the above noted factors, the Company determined that it is not the primary beneficiary and does not consolidate PACT since it does not have the power to direct the activities that most significantly impact PACT’s economic performance. The Company does not have the ability to exercise significant influence over PACT and accounts for its investment in PACT preferred stock under the measurement alternative. The Company recognized its investment in PACT preferred stock at its estimated fair value of $2.9 million on October 1, 2022, which was included in the Company’s Consolidated Balance Sheets within other investments. The Company’s maximum exposure to loss from PACT is limited to the carrying value of its investment in PACT preferred stock. In connection with the preparation of the financial statements for the three months ended June 30, 2023, the Company performed a qualitative assessment of potential indicators of impairment and determined that indicators existed for the Company’s PACT Series D convertible preferred stock investment. While there was no single event or factor, the Company considered PACT’s operating cash flow requirements over the next year, liquid asset balances to fund

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following table sets forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands): June 30, 2023 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 116,970 $ — $ — $ 116,970 U.S. Treasury securities — 291,289 — 291,289 U.S. government agency securities — 94,511 — 94,511 Corporate debt securities — 106,468 — 106,468 Total financial assets $ 116,970 $ 492,268 $ — $ 609,238 Financial liabilities: Success payment liabilities $ — $ — $ 3,753 $ 3,753 Total financial liabilities $ — $ — $ 3,753 $ 3,753 December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 67,970 $ — $ — $ 67,970 U.S. Treasury securities — 271,799 — 271,799 U.S. government agency securities — 134,045 — 134,045 Corporate debt securities — 220,681 — 220,681 Total financial assets $ 67,970 $ 626,525 $ — $ 694,495 Financial liabilities: Success payment liabilities $ — $ — $ 4,356 $ 4,356 Total financial liabilities $ — $ — $ 4,356 $ 4,356 The Company measures the fair value of money market funds based on quoted prices in active markets for identical assets or liabilities. The Level 2 marketable securities include U.S. Treasury securities, U.S. government agency securities and corporate debt securities. The Company’s Level 2 securities are valued using third-party pricing sources. The pricing services applied industry standard valuation models. Inputs utilized include market pricing based on real-time trade data for the same or similar securities and other significant inputs derived from or corroborated by observable market data. The Company’s Level 3 financial instruments fair values are estimated using valuation models, including Monte Carlo simulations for the Company’s success payment liabilities. Monte Carlo simulations model the future movement of stock prices based on several key variables combined with empirical knowledge of the process governing the behavior of the stock price. The following variables were incorporated in the estimated fair value of the success payment liabilities: fair value of the Company’s common stock, expected volatility, the risk-free interest rate and the estimated number and timing of valuation measurement dates on the basis of which payments may be triggered. The computation of expected volatility was estimated based on available information about the historical volatility of stocks of similar publicly traded companies for a period matching the expected term assumption. The following assumptions were incorporated into the calculation of the estimated fair value of the Fred Hutch success payment liability: June 30, December 31, Fair value of common stock $ 3.18 $ 3.47 Risk-free interest rate 3.36% - 5.26% 3.58% - 4.65% Expected volatility 80.0 % 80.0 % Expected term (in years) 0.96 - 4.47 0.46 - 4.97 The following assumptions were incorporated into the calculation of the estimated fair value of the Stanford success payment liability: June 30, December 31, Fair value of common stock $ 3.18 $ 3.47 Risk-free interest rate 3.36% - 5.26% 3.58% - 4.65% Expected volatility 80.0 % 80.0 % Expected term (in years) 0.96 - 6.25 0.46 - 6.75 The Company utilizes estimates and assumptions in determining the estimated success payment liabilities and associated changes in fair value. A small change in the valuation of the Company’s common stock may have a relatively large change in the estimated fair value of the success payment liability and associated changes in fair value. The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 liabilities (in thousands): Success Payment Balance at December 31, 2022 $ 4,356 Change in fair value (1) (603) Balance at June 30, 2023 $ 3,753 (1) The changes in the fair value associated with the Fred Hutch success payment liabilities of approximately $(0.6) million are recorded in other (expense) income, net (See Note 3, License, Collaboration and Success Payment Agreements ). The changes in the fair value of approximately zero associated with the Stanford success payment liabilities are recorded as research and development expenses. In October 2022, the Company received non-voting Series D convertible preferred stock pursuant to the settlement agreement with PACT (See Note 3, License, Collaboration and Success Payment Agreements ). The Company determined the fair value of PACT was a fraction of the aggregate liquidation preference of the Company’s PACT Series D convertible preferred stock. The Company determined that the fair value of its investment in PACT preferred stock is approximated by the fair value of the PACT business since the Company is the only party invested in PACT Series D convertible preferred stock, the most senior class of stock issued by PACT, as of October 1, 2022. The fair value of PACT was estimated at $2.9 million as of October 1, 2022 using the cost approach. Under this approach, the fair value of an asset is measured by the cost to reconstruct or replace such asset with another one of like utility. The fair value of PACT was estimated by using significant unobservable inputs, including an estimate of insignificant fair value associated with PACT intangible assets. Accordingly, the Company classified the fair value measurement of PACT Series D convertible preferred stock on October 1, 2022 as Level 3 under the fair value hierarchy. In connection with the preparation of the financial statements for the three and six months ended June 30, 2023, the Company performed a qualitative assessment of potential indicators of impairment, resulting in the impairment of the $2.9 million PACT Series D convertible preferred stock investment. See Note 5, Other Investments , for additional details regarding the PACT investment impairment.

Leases

Leases	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Leases	Leases The Company’s lease portfolio is comprised of operating leases for laboratory, office and manufacturing facilities located in South San Francisco, California, and Seattle and Bothell, Washington with contractual periods expiring between December 2028 and March 2031. In addition to minimum rent, the leases require payment of real estate taxes, insurance, common area maintenance charges and other executory costs. These additional charges are considered variable lease costs and are recognized in the period in which the costs are incurred. The following table summarizes the Company’s future minimum operating lease commitments, including expected lease incentives to be received, as of June 30, 2023 (in thousands): Year Ending December 31: 2023 (remaining six months) $ 5,630 2024 11,347 2025 11,859 2026 12,209 2027 12,569 Thereafter 35,525 Total undiscounted lease payments 89,139 Less: imputed interest (23,065) Total operating lease liabilities $ 66,074 Reported as of June 30, 2023: Short-term portion of lease liabilities (included in accrued liabilities and other current liabilities) $ 5,853 Operating lease liabilities, non-current 60,221 Total $ 66,074 The operating lease costs for all operating leases were $2.3 million and $2.2 million for the three months ended June 30, 2023 and 2022, respectively, and $4.4 million and $4.7 million for the six months ended June 30, 2023 and 2022, respectively. The operating lease costs and total commitments for short-term leases were de minimis for the three and six months ended June 30, 2023 and 2022. Variable lease costs for operating leases were $1.4 million and $1.2 million for the three months ended June 30, 2023 and 2022, respectively, and $2.8 million and $2.5 million for the six months ended June 30, 2023 and 2022, respectively. The weighted-average remaining lease terms for operating leases were 7.3 and 7.8 years as of June 30, 2023 and December 31, 2022, respectively. The weighted-average discount rates for operating leases were 8.5% as of both June 30, 2023 and December 31, 2022. In May 2021, the Company entered into a sublease, whereby the Company agreed to sublease approximately 11,000 square feet of its space in South San Francisco, California currently leased by the Company. The sublease is classified as an operating lease and will expire in March 2031. The Company recognized sublease income for this sublease of $0.2 million for both the three months ended June 30, 2023 and 2022, and $0.4 million for both the six months ended June 30, 2023 and 2022. In September 2021, the Company entered into a sublease with Sonoma Biotherapeutics, Inc. (“Sonoma”), a related party, whereby the Company agreed to sublease approximately 18,000 square feet of space in South San Francisco, California currently leased by the Company. See Note 12, Related-Party Transactions. As a part of the sublease, in September 2021, the Company received a $4.6 million tenant improvement contribution payment, which is recognized over the term of the sublease. The sublease is classified as an operating lease and will expire in March 2031. The Company recognized Sonoma sublease income of $0.5 million for both the three months ended June 30, 2023 and 2022 and $0.9 million for both the six months ended June 30, 2023 and 2022. The Company's sublease income is recognized within other operating income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss.
Leases	Leases The Company’s lease portfolio is comprised of operating leases for laboratory, office and manufacturing facilities located in South San Francisco, California, and Seattle and Bothell, Washington with contractual periods expiring between December 2028 and March 2031. In addition to minimum rent, the leases require payment of real estate taxes, insurance, common area maintenance charges and other executory costs. These additional charges are considered variable lease costs and are recognized in the period in which the costs are incurred. The following table summarizes the Company’s future minimum operating lease commitments, including expected lease incentives to be received, as of June 30, 2023 (in thousands): Year Ending December 31: 2023 (remaining six months) $ 5,630 2024 11,347 2025 11,859 2026 12,209 2027 12,569 Thereafter 35,525 Total undiscounted lease payments 89,139 Less: imputed interest (23,065) Total operating lease liabilities $ 66,074 Reported as of June 30, 2023: Short-term portion of lease liabilities (included in accrued liabilities and other current liabilities) $ 5,853 Operating lease liabilities, non-current 60,221 Total $ 66,074 The operating lease costs for all operating leases were $2.3 million and $2.2 million for the three months ended June 30, 2023 and 2022, respectively, and $4.4 million and $4.7 million for the six months ended June 30, 2023 and 2022, respectively. The operating lease costs and total commitments for short-term leases were de minimis for the three and six months ended June 30, 2023 and 2022. Variable lease costs for operating leases were $1.4 million and $1.2 million for the three months ended June 30, 2023 and 2022, respectively, and $2.8 million and $2.5 million for the six months ended June 30, 2023 and 2022, respectively. The weighted-average remaining lease terms for operating leases were 7.3 and 7.8 years as of June 30, 2023 and December 31, 2022, respectively. The weighted-average discount rates for operating leases were 8.5% as of both June 30, 2023 and December 31, 2022. In May 2021, the Company entered into a sublease, whereby the Company agreed to sublease approximately 11,000 square feet of its space in South San Francisco, California currently leased by the Company. The sublease is classified as an operating lease and will expire in March 2031. The Company recognized sublease income for this sublease of $0.2 million for both the three months ended June 30, 2023 and 2022, and $0.4 million for both the six months ended June 30, 2023 and 2022. In September 2021, the Company entered into a sublease with Sonoma Biotherapeutics, Inc. (“Sonoma”), a related party, whereby the Company agreed to sublease approximately 18,000 square feet of space in South San Francisco, California currently leased by the Company. See Note 12, Related-Party Transactions. As a part of the sublease, in September 2021, the Company received a $4.6 million tenant improvement contribution payment, which is recognized over the term of the sublease. The sublease is classified as an operating lease and will expire in March 2031. The Company recognized Sonoma sublease income of $0.5 million for both the three months ended June 30, 2023 and 2022 and $0.9 million for both the six months ended June 30, 2023 and 2022. The Company's sublease income is recognized within other operating income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock The Company is authorized to issue 10.0 million shares of preferred stock with a par value of $0.0001 per share. As of June 30, 2023 and December 31, 2022, no shares of preferred stock were outstanding. Common Stock The Company is authorized to issue 500.0 million shares of common stock with a par value of $0.0001 per share. As of June 30, 2023 and December 31, 2022, there were 251,026,997 shares and 249,567,343 shares of the Company’s common stock outstanding, respectively. On August 4, 2022, the Company entered into an Equity Distribution Agreement with Goldman Sachs & Co. LLC (“Goldman Sachs”) and BofA Securities, Inc. (“BofA”, and together with Goldman Sachs, the “Agents”) with respect to an at-the-market offering program (the “Equity Distribution Agreement”). In accordance with the terms of the Equity Distribution Agreement, the Company may offer and sell from time to time through the Agents shares of the Company’s common stock having an aggregate offering amount of up to $200.0 million (the “Placement Shares”). Sales of the Placement Shares, if any, will be made at prevailing market prices on Nasdaq at the time of sale, or as otherwise agreed with the Agents, by any method permitted by law deemed to be an “at-the-market offering” as defined in Rule 415 of the Securities Act of 1933, as amended. The Company will pay commissions to the Agents of up to 3.0% of the gross proceeds of the sale of the Placement Shares sold under the Equity Distribution Agreement and reimburse the Agents for certain expenses. Neither the Company nor the Agents are obligated to sell any shares and, to date, the Company has not made any sales under the Equity Distribution Agreement.

Stock-based Compensation

Stock-based Compensation	6 Months Ended
	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	Stock-based Compensation 2021 Equity Incentive Plan In June 2021, the Company adopted the 2021 Equity Incentive Plan (“2021 Plan”), which on the date of the underwriting agreement related to the Company’s IPO became effective with an initial reserve of 26,662,087 shares, plus any shares subject to outstanding awards granted under the 2018 Equity Incentive Plan (“2018 Plan”) that, on or after the effectiveness of the 2021 Plan, terminate or expire before exercise or settlement, are not issued because the award is settled in cash, are forfeited because of the failure to vest, or are reacquired or withheld (or not issued) to satisfy a tax withholding obligation or the purchase or exercise price. In addition, the number of shares reserved for issuance under the 2021 Plan automatically increases on January 1 of each year for a period of ten years, beginning on January 1, 2022 and continuing through January 1, 2031, in an amount equal to (1) 5% of the total number of shares of the Company’s common stock outstanding on December 31 of the immediately preceding year, or (2) a lesser number of shares determined by the Company’s board of directors no later than December 31 of the immediately preceding year. On January 1, 2023, the Company reserved an additional 12,478,367 shares of common stock for issuance under the 2021 Plan representing 5% of the total common shares outstanding as of December 31, 2022. Under the 2021 Plan, the Company may grant incentive stock options, non-statutory stock options, restricted stock awards (“RSAs”), restricted stock units (“RSUs”), stock appreciation rights, performance awards and other stock-based awards. Terms of stock awards, including vesting requirements, are determined by the Company’s board of directors or by a committee authorized by the Company’s board of directors, subject to provisions of the 2021 Plan. The term of any stock option granted under the 2021 Plan cannot exceed ten years. Generally, awards granted by the Company vest over four years but may be granted with different vesting terms. In conjunction with adopting the 2021 Plan, the Company discontinued the 2018 Plan with respect to new equity awards. As of June 30, 2023, 25,280,983 shares were available for future issuance pursuant to the 2021 Plan. 2021 Employee Stock Purchase Plan In June 2021, the Company adopted the 2021 Employee Stock Purchase Plan (“2021 ESPP”), which became effective immediately prior to the execution of the underwriting agreement related to the Company’s IPO with an initial reserve of 2,470,000 shares. The 2021 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their earnings, subject to plan limitations. Unless otherwise determined by the Company’s board of directors, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first date of an offering or on the purchase date. The number of shares of the Company’s common stock reserved for issuance under the 2021 ESPP automatically increases on January 1 of each year for a period of ten years, beginning on January 1, 2022 and continuing through January 1, 2031, by the lesser of (1) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the immediately preceding year, and (2) 4,940,000 shares; provided, however, that the Company’s board of directors may act to provide a lesser increase in number of shares. The Company’s board of directors elected to reserve no additional shares under the 2021 ESPP for the year beginning January 1, 2023. The Company may specify offerings with durations not more than 27 months and may specify shorter purchase periods within each offering. Under the 2021 ESPP, 542,921 shares were issued for the three and six months ended June 30, 2023 and 283,574 shares were issued for the three and six months ended June 30, 2022. As of June 30, 2023, 3,905,099 shares were available for future issuance pursuant to the 2021 ESPP. 2018 Equity Incentive Plan In 2018, the Company established the 2018 Plan that provided for the grant of incentive stock options, non‑statutory stock options, RSAs, RSUs, stock appreciation rights and other stock-based awards. Terms of stock awards, including vesting requirements, were determined by the board of directors or by a committee authorized by the Company’s board of directors, subject to provisions of the 2018 Plan. The term of any stock option granted under the 2018 Plan cannot exceed ten years. Generally, awards granted by the Company vest over four years, but could have been granted with different vesting terms. Pursuant to the terms of the 2021 Plan, any shares subject to outstanding options originally granted under the 2018 Plan that terminate, expire or lapse for any reason without the delivery of shares to the holder thereof become available for issuance pursuant to awards granted under the 2021 Plan. While no shares are available for future issuance under the 2018 Plan, it continues to govern outstanding equity awards granted thereunder. Stock-based Compensation Expense Stock-based compensation expense by classification included within the Condensed Consolidated Statements of Operations and Comprehensive Loss was as follows (in thousands): Three Months Ended Six Months Ended 2023 2022 2023 2022 Research and development $ 5,279 $ 4,195 $ 9,891 $ 7,959 General and administrative 8,944 18,215 18,214 36,479 Total stock-based compensation expense $ 14,223 $ 22,410 $ 28,105 $ 44,438 At June 30, 2023, total stock-based compensation cost related to unvested awards not yet recognized was $81.6 million, which is expected to be recognized over a remaining weighted-average period of 2.86 years. Restricted Stock Units A summary of the Company’s RSU activity was as follows: Restricted Stock Units Outstanding Weighted-Average Unvested RSUs as of December 31, 2022 872,077 $ 5.98 RSUs granted 1,997,177 $ 2.16 RSUs vested (127,886) $ 5.98 RSUs forfeited or canceled (117,669) $ 4.28 Unvested RSUs as of June 30, 2023 2,623,699 $ 3.15 Stock Options A summary of the Company’s stock option activity was as follows: Number of Stock Options Weighted- Weighted- Aggregate Options outstanding as of December 31, 2022 53,849,045 $ 5.09 7.84 $ 24,887 Granted 8,586,063 $ 2.23 Exercised (832,840) $ 0.10 Canceled or forfeited (2,959,671) $ 5.12 Options outstanding as of June 30, 2023 58,642,597 $ 4.74 7.73 $ 26,401 Options exercisable as of June 30, 2023 30,365,614 $ 4.77 6.61 $ 18,878 The fair value of stock options granted to employees, directors and consultants was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted-average assumptions: Six Months Ended 2023 2022 Risk-free interest rate 4.09 % 2.28 % Expected volatility 92.4 % 85.5 % Expected term (in years) 5.99 5.98 Expected dividend yield 0 % 0 %

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per ShareBasic and diluted net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. The Company’s potentially dilutive shares, which include unvested RSAs, unvested RSUs and options to purchase common stock, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Shares subject to options to purchase common stock, unvested RSAs and unvested RSUs were all excluded from consideration in the calculation of diluted net loss per share in all periods presented due to their anti-dilutive effects.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies License and Collaboration Agreements The Company has entered into certain license and collaboration agreements, including those identified in Note 3, License, Collaboration and Success Payment Agreements above, with third parties that include the funding of certain development, manufacturing and commercialization efforts with the potential for future milestone and royalty payments upon the achievement of pre-established developmental, regulatory and/or commercial milestones. The Company’s

Related-party Transactions

Related-party Transactions	6 Months Ended
	Jun. 30, 2023
Related Party Transactions [Abstract]
Related-party Transactions	Related-party Transactions In September 2021, the Company entered into a sublease with Sonoma (“Sonoma Sublease”), with whom the Company has common stockholders with board seats, whereby the Company agreed to sublease approximately 18,000 square feet of space in South San Francisco, California currently leased by the Company. Dr. Klausner, the Chair of the Company’s board of directors, also serves as Board Chair of the board of directors of Sonoma. As a part of the Sonoma Sublease, a $4.6 million tenant improvement contribution payment was made by Sonoma, which is recognized over the term of the Sonoma Sublease. As of both June 30, 2023 and December 31, 2022, there were accrued liabilities and other current liabilities of $0.5 million, and as of June 30, 2023 and December 31, 2022, there were other non-current liabilities of $3.3 million and $3.5 million, respectively, in connection with the Sonoma Sublease. Total operating income from Sonoma and income solely attributable to the Sonoma Sublease are shown in the table below (in thousands). Total operating income includes income attributable to the sublease, as well as additional operating fees recognized in “other operating income, net” such as common area maintenance charges. See Note 7, Leases , for more detail on the Sonoma Sublease. Three Months Ended Six Months Ended 2023 2022 2023 2022 Sonoma other operating income, net $ 648 $ 658 $ 1,317 $ 1,317 Sonoma sublease income $ 464 $ 466 $ 930 $ 931 The Company was party to the GSK Agreement with GSK, which is a holder of more than 10% of the Company’s outstanding common stock. See Note 3, License, Collaboration and Success Payment Agreements

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pay vs Performance Disclosure
Net loss	$ (63,890)	$ (36,323)	$ (130,849)	$ (104,467)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiary.
Consolidations	All significant intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the Company’s Condensed Consolidated Financial Statements in conformity with GAAP requires management to make judgments, estimates and assumptions that affect reported amounts and related disclosures. Specific accounts that require management estimates include, but are not limited to, stock-based compensation, valuation of success payments, valuation of other investments, revenue recognition and accrued expenses. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates. In June 2022, the Company recorded an adjustment to revenue related to a change in estimate in connection with the Collaboration and License Agreement, entered into in 2019 and amended in June 2020 and December 2021 (“GSK Agreement”) with GlaxoSmithKline Intellectual Property (No. 5) Limited and Glaxo Group Limited (together, “GSK”). The Company and GSK mutually agreed to conclude research activities on an undisclosed target for hematological cancers in June 2022. As a result, the Company decreased the related estimated project costs, which resulted in an increase in the measure of proportional cumulative performance.
Concentrations of Credit Risk	Concentrations of Credit Risk and Off-balance Sheet RiskThe Company maintains its cash, cash equivalents and restricted cash with high quality, accredited financial institutions. Restricted cash is cash held in bank accounts and is used as collateral associated with the Company’s corporate credit card program. Cash, cash equivalents and restricted cash amounts, at times, may exceed federally insured limits. The Company also makes short-term investments in money market funds, U.S. Treasury securities, U.S. government agency securities and corporate debt securities, which can be subject to certain credit risk. However, the Company mitigates the risks by investing in high‑grade instruments, limiting exposure to any one issuer or type of investment and monitoring the ongoing creditworthiness of the financial institutions and issuers. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to significant risk on these funds.
Off-balance Sheet Risk	The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.
Significant Accounting Policies	Significant Accounting Policies There have been no material changes to the significant accounting policies from the Annual Report on Form 10-K for the year ended December 31, 2022.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements None.

License, Collaboration, and S_2

License, Collaboration, and Success Payment Agreements (Tables)	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Aggregate Potential Success Payments	The following table summarizes the aggregate potential success payments, which are payable to Fred Hutch in cash or cash equivalents, or at the Company’s discretion, publicly-tradeable shares of the Company’s common stock: Multiple of initial equity value at issuance 10x 20x 30x 40x 50x Per share common stock price required for payment $ 18.29 $ 36.58 $ 54.86 $ 73.15 $ 91.44 Aggregate success payment(s) (in millions) $ 10 $ 40 $ 90 $ 140 $ 200 The following table summarizes the aggregate potential success payments, which are payable to Stanford in cash or cash equivalents, or at the Company’s discretion, publicly-tradeable shares of the Company’s common stock: Multiple of initial equity value at issuance 10x 20x 30x 40x 50x Per share common stock price required for payment $ 18.29 $ 36.58 $ 54.86 $ 73.15 $ 91.44 Aggregate success payment(s) (in millions) $ 10 $ 40 $ 90 $ 140 $ 200

Cash Equivalents and Marketab_2

Cash Equivalents and Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2023
Cash and Cash Equivalents [Abstract]
Schedule of Fair Value and Amortized Cost of Cash Equivalents	The fair value and amortized cost of cash equivalents and marketable securities by major security type are as follows (in thousands): June 30, 2023 Amortized Cost Gross Gross Unrealized Losses Fair Value Money market funds $ 116,970 $ — $ — $ 116,970 U.S. Treasury securities 292,610 31 (1,352) 291,289 U.S. government agency securities 95,331 — (820) 94,511 Corporate debt securities 106,706 — (238) 106,468 Total cash equivalents and marketable securities $ 611,617 $ 31 $ (2,410) $ 609,238 Classified as: Fair Value Cash equivalents $ 200,910 Marketable securities 371,376 Marketable securities, non-current 36,952 Total cash equivalents and marketable securities $ 609,238 December 31, 2022 Amortized Cost Gross Gross Unrealized Losses Fair Value Money market funds $ 67,970 $ — $ — $ 67,970 U.S. Treasury securities 277,056 — (5,257) 271,799 U.S. government agency securities 135,460 1 (1,416) 134,045 Corporate debt securities 221,608 3 (930) 220,681 Total cash equivalents and marketable securities $ 702,094 $ 4 $ (7,603) $ 694,495 Classified as: Fair Value Cash equivalents $ 107,780 Marketable securities 516,598 Marketable securities, non-current 70,117 Total cash equivalents and marketable securities $ 694,495
Schedule of Fair Value and Amortized Cost of Marketable Securities	The fair value and amortized cost of cash equivalents and marketable securities by major security type are as follows (in thousands): June 30, 2023 Amortized Cost Gross Gross Unrealized Losses Fair Value Money market funds $ 116,970 $ — $ — $ 116,970 U.S. Treasury securities 292,610 31 (1,352) 291,289 U.S. government agency securities 95,331 — (820) 94,511 Corporate debt securities 106,706 — (238) 106,468 Total cash equivalents and marketable securities $ 611,617 $ 31 $ (2,410) $ 609,238 Classified as: Fair Value Cash equivalents $ 200,910 Marketable securities 371,376 Marketable securities, non-current 36,952 Total cash equivalents and marketable securities $ 609,238 December 31, 2022 Amortized Cost Gross Gross Unrealized Losses Fair Value Money market funds $ 67,970 $ — $ — $ 67,970 U.S. Treasury securities 277,056 — (5,257) 271,799 U.S. government agency securities 135,460 1 (1,416) 134,045 Corporate debt securities 221,608 3 (930) 220,681 Total cash equivalents and marketable securities $ 702,094 $ 4 $ (7,603) $ 694,495 Classified as: Fair Value Cash equivalents $ 107,780 Marketable securities 516,598 Marketable securities, non-current 70,117 Total cash equivalents and marketable securities $ 694,495

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table sets forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands): June 30, 2023 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 116,970 $ — $ — $ 116,970 U.S. Treasury securities — 291,289 — 291,289 U.S. government agency securities — 94,511 — 94,511 Corporate debt securities — 106,468 — 106,468 Total financial assets $ 116,970 $ 492,268 $ — $ 609,238 Financial liabilities: Success payment liabilities $ — $ — $ 3,753 $ 3,753 Total financial liabilities $ — $ — $ 3,753 $ 3,753 December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 67,970 $ — $ — $ 67,970 U.S. Treasury securities — 271,799 — 271,799 U.S. government agency securities — 134,045 — 134,045 Corporate debt securities — 220,681 — 220,681 Total financial assets $ 67,970 $ 626,525 $ — $ 694,495 Financial liabilities: Success payment liabilities $ — $ — $ 4,356 $ 4,356 Total financial liabilities $ — $ — $ 4,356 $ 4,356
Schedule of Estimated Fair Value of Success Payment Liability Assumptions	The following assumptions were incorporated into the calculation of the estimated fair value of the Fred Hutch success payment liability: June 30, December 31, Fair value of common stock $ 3.18 $ 3.47 Risk-free interest rate 3.36% - 5.26% 3.58% - 4.65% Expected volatility 80.0 % 80.0 % Expected term (in years) 0.96 - 4.47 0.46 - 4.97 The following assumptions were incorporated into the calculation of the estimated fair value of the Stanford success payment liability: June 30, December 31, Fair value of common stock $ 3.18 $ 3.47 Risk-free interest rate 3.36% - 5.26% 3.58% - 4.65% Expected volatility 80.0 % 80.0 % Expected term (in years) 0.96 - 6.25 0.46 - 6.75
Schedule of Changes in the Estimated Fair Value of Level 3 Financial Assets	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 liabilities (in thousands): Success Payment Balance at December 31, 2022 $ 4,356 Change in fair value (1) (603) Balance at June 30, 2023 $ 3,753 (1) The changes in the fair value associated with the Fred Hutch success payment liabilities of approximately $(0.6) million are recorded in other (expense) income, net (See Note 3, License, Collaboration and Success Payment Agreements ). The changes in the fair value of approximately zero associated with the Stanford success payment liabilities are recorded as research and development expenses.
Schedule of Changes in the Estimated Fair Value of Level 3 Financial Liabilities	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 liabilities (in thousands): Success Payment Balance at December 31, 2022 $ 4,356 Change in fair value (1) (603) Balance at June 30, 2023 $ 3,753 (1) The changes in the fair value associated with the Fred Hutch success payment liabilities of approximately $(0.6) million are recorded in other (expense) income, net (See Note 3, License, Collaboration and Success Payment Agreements ). The changes in the fair value of approximately zero associated with the Stanford success payment liabilities are recorded as research and development expenses.

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Schedule of Future Minimum Operating Lease Commitments, Including Expected Lease Incentives to be Received	The following table summarizes the Company’s future minimum operating lease commitments, including expected lease incentives to be received, as of June 30, 2023 (in thousands): Year Ending December 31: 2023 (remaining six months) $ 5,630 2024 11,347 2025 11,859 2026 12,209 2027 12,569 Thereafter 35,525 Total undiscounted lease payments 89,139 Less: imputed interest (23,065) Total operating lease liabilities $ 66,074 Reported as of June 30, 2023: Short-term portion of lease liabilities (included in accrued liabilities and other current liabilities) $ 5,853 Operating lease liabilities, non-current 60,221 Total $ 66,074
Schedule of Lease Assets and Liabilities	The following table summarizes the Company’s future minimum operating lease commitments, including expected lease incentives to be received, as of June 30, 2023 (in thousands): Year Ending December 31: 2023 (remaining six months) $ 5,630 2024 11,347 2025 11,859 2026 12,209 2027 12,569 Thereafter 35,525 Total undiscounted lease payments 89,139 Less: imputed interest (23,065) Total operating lease liabilities $ 66,074 Reported as of June 30, 2023: Short-term portion of lease liabilities (included in accrued liabilities and other current liabilities) $ 5,853 Operating lease liabilities, non-current 60,221 Total $ 66,074

Stock-based Compensation (Table

Stock-based Compensation (Tables)	6 Months Ended
	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Stock-based Compensation Expense by Classification	Stock-based compensation expense by classification included within the Condensed Consolidated Statements of Operations and Comprehensive Loss was as follows (in thousands): Three Months Ended Six Months Ended 2023 2022 2023 2022 Research and development $ 5,279 $ 4,195 $ 9,891 $ 7,959 General and administrative 8,944 18,215 18,214 36,479 Total stock-based compensation expense $ 14,223 $ 22,410 $ 28,105 $ 44,438
Schedule of RSU Activity	A summary of the Company’s RSU activity was as follows: Restricted Stock Units Outstanding Weighted-Average Unvested RSUs as of December 31, 2022 872,077 $ 5.98 RSUs granted 1,997,177 $ 2.16 RSUs vested (127,886) $ 5.98 RSUs forfeited or canceled (117,669) $ 4.28 Unvested RSUs as of June 30, 2023 2,623,699 $ 3.15
Schedule of Stock Option Activity	A summary of the Company’s stock option activity was as follows: Number of Stock Options Weighted- Weighted- Aggregate Options outstanding as of December 31, 2022 53,849,045 $ 5.09 7.84 $ 24,887 Granted 8,586,063 $ 2.23 Exercised (832,840) $ 0.10 Canceled or forfeited (2,959,671) $ 5.12 Options outstanding as of June 30, 2023 58,642,597 $ 4.74 7.73 $ 26,401 Options exercisable as of June 30, 2023 30,365,614 $ 4.77 6.61 $ 18,878
Schedule of Assumptions Used in Black-Scholes Option-Pricing Model for Estimating Fair Value of Stock Options Granted	The fair value of stock options granted to employees, directors and consultants was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted-average assumptions: Six Months Ended 2023 2022 Risk-free interest rate 4.09 % 2.28 % Expected volatility 92.4 % 85.5 % Expected term (in years) 5.99 5.98 Expected dividend yield 0 % 0 %

Related-party Transactions (Tab

Related-party Transactions (Tables)	6 Months Ended
	Jun. 30, 2023
Related Party Transactions [Abstract]
Schedule of Total Income Attributable to Sonoma Sublease	Total operating income from Sonoma and income solely attributable to the Sonoma Sublease are shown in the table below (in thousands). Total operating income includes income attributable to the sublease, as well as additional operating fees recognized in “other operating income, net” such as common area maintenance charges. See Note 7, Leases , for more detail on the Sonoma Sublease. Three Months Ended Six Months Ended 2023 2022 2023 2022 Sonoma other operating income, net $ 648 $ 658 $ 1,317 $ 1,317 Sonoma sublease income $ 464 $ 466 $ 930 $ 931

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue	[1]	$ 27	$ 35,741	$ 92	$ 36,294
Net loss		$ (63,890)	$ (36,323)	$ (130,849)	$ (104,467)
Net loss per common share, basic (in dollars per share)		$ (0.26)	$ (0.15)	$ (0.52)	$ (0.43)
Net loss per common share, diluted (in dollars per share)		$ (0.26)	$ (0.15)	$ (0.52)	$ (0.43)
GSK | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Adjustment To Revenue Related To Change In Estimate
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue			$ 35,300		$ 35,300
Net loss			$ 35,300		$ 35,300
Net loss per common share, basic (in dollars per share)			$ 0.14		$ 0.14
Net loss per common share, diluted (in dollars per share)			$ 0.14		$ 0.14
[1](1)    None of the revenue for the three and six months ended June 30, 2023 was from a related-party. Substantially all of the revenue for the three and six months ended June 30, 2022 was from a related-party.

License, Collaboration, and S_3

License, Collaboration, and Success Payment Agreements - Narrative (Details)		1 Months Ended		3 Months Ended			6 Months Ended
	Oct. 01, 2022 USD ($)	Jun. 30, 2020 USD ($) $ / shares shares	May 31, 2019 USD ($) $ / shares shares	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Oct. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) $ / shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development expense				$ 47,471,000	$ 43,719,000		$ 92,101,000	$ 79,549,000
Impairment of other investments				2,923,000	0		12,923,000	0
Settled Litigation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Ownership of fully diluted shares (as a percent)	80%
PACT
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Impairment of other investments						$ 36,400,000
Series A Convertible Preferred Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Convertible preferred stock, par value (in dollars per share) | $ / shares										$ 1.83		$ 1.83
Fred Hutch | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual license maintenance payments												$ 50,000
Aggregate research payments due												$ 12,000,000
Term of collaborative arrangement for research												6 years
Research and development expense				100,000	500,000		400,000	1,000,000
Aggregate success payment(s) (in millions)				0			0
Term of success payment agreement												9 years
Trigger period from IPO date												1 year
Trigger period thereafter												2 years
Fair value of potential success payments due				1,900,000			1,900,000		$ 2,500,000
Success payment expense (gain)				500,000	2,200,000		(600,000)	(600,000)
Fred Hutch | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance												10
Aggregate success payment(s) (in millions)												$ 10,000,000
Per share common stock price required for payment (in dollars per share) | $ / shares												$ 18.29
Fred Hutch | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance												50
Aggregate success payment(s) (in millions)												$ 200,000,000
Per share common stock price required for payment (in dollars per share) | $ / shares												$ 91.44
Stanford | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual license maintenance payments											$ 50,000
Aggregate research payments due										$ 12,000,000
Term of collaborative arrangement for research										4 years
Research and development expense				700,000	800,000		1,500,000	1,500,000
Aggregate success payment(s) (in millions)				0			0
Term of success payment agreement										9 years
Trigger period from IPO date										1 year
Trigger period thereafter										2 years
Fair value of potential success payments due				2,700,000			2,700,000		3,300,000
Success payment expense (gain)				600,000	1,400,000		0	400,000
Success payment liability				1,900,000			1,900,000		1,900,000
Stanford | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments due											2,500,000
Stanford | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance										10
Aggregate success payment(s) (in millions)										$ 10,000,000
Per share common stock price required for payment (in dollars per share) | $ / shares										$ 18.29
Stanford | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance										50
Aggregate success payment(s) (in millions)										$ 200,000,000
Per share common stock price required for payment (in dollars per share) | $ / shares										$ 91.44
Stanford | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Maximum | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments due											$ 3,700,000
GSK | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract liabilities				0			0		0
Revenue recognized				0	35,700,000		0	36,300,000
GSK | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Adjustment To Revenue Related To Change In Estimate
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized					$ 35,300,000			$ 35,300,000
GSK | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract liabilities			$ 45,000,000	0			0		0
Stock purchase agreement portion of transaction price			58,600,000
Transaction price			$ 103,600,000
Contract assets				$ 0			$ 0		$ 0
GSK | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | License | Series AA Convertible Preferred Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock sold under stock purchase program (in shares) | shares			30,253,189
Price per share of stock sold under stock purchase program (in dollars per share) | $ / shares			$ 6.78
Fair value per share of stock sold under stock purchase program (in dollars per share) | $ / shares			$ 4.84
PACT
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Gain on other investments	$ 2,900,000
PACT | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment		$ 50,000,000
Stock purchase agreement, stock purchased (in shares) | shares		17,806,901
Stock purchase agreement, purchase price per share (in dollars per share) | $ / shares		$ 2.81
Stock purchase agreement, fair value per share (in dollars per share) | $ / shares		$ 2.05
Additional purchase price consideration		$ 13,600,000
Total upfront payment paid		63,600,000
PACT | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Other Investment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Strategic equity investment		$ 36,400,000

License, Collaboration, and S_4

License, Collaboration, and Success Payment Agreements - Schedule of Aggregate Potential Success Payments (Details) - Collaborative Arrangement, Transaction with Party to Collaborative Arrangement	Jun. 30, 2023 USD ($)	Oct. 31, 2020 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares
Fred Hutch
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate success payment(s) (in millions)	$ 0
Stanford
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate success payment(s) (in millions)	$ 0
Ten Times | Fred Hutch
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance			10
Per share common stock price required for payment (in dollars per share) | $ / shares			$ 18.29
Aggregate success payment(s) (in millions)			$ 10,000,000
Ten Times | Stanford
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance		10
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 18.29
Aggregate success payment(s) (in millions)		$ 10,000,000
Twenty Times | Fred Hutch
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance			20
Per share common stock price required for payment (in dollars per share) | $ / shares			$ 36.58
Aggregate success payment(s) (in millions)			$ 40,000,000
Twenty Times | Stanford
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance		20
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 36.58
Aggregate success payment(s) (in millions)		$ 40,000,000
Thirty Times | Fred Hutch
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance			30
Per share common stock price required for payment (in dollars per share) | $ / shares			$ 54.86
Aggregate success payment(s) (in millions)			$ 90,000,000
Thirty Times | Stanford
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance		30
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 54.86
Aggregate success payment(s) (in millions)		$ 90,000,000
Forty Times | Fred Hutch
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance			40
Per share common stock price required for payment (in dollars per share) | $ / shares			$ 73.15
Aggregate success payment(s) (in millions)			$ 140,000,000
Forty Times | Stanford
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance		40
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 73.15
Aggregate success payment(s) (in millions)		$ 140,000,000
Fifty Times | Fred Hutch
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance			50
Per share common stock price required for payment (in dollars per share) | $ / shares			$ 91.44
Aggregate success payment(s) (in millions)			$ 200,000,000
Fifty Times | Stanford
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Multiple of initial equity value at issuance		50
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 91.44
Aggregate success payment(s) (in millions)		$ 200,000,000

Cash Equivalents and Marketab_3

Cash Equivalents and Marketable Securities - Schedule of Fair Value and Amortized Cost of Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Marketable Securities [Line Items]
Amortized Cost	$ 224,372	$ 123,554	$ 205,739
Amortized Cost	611,617	702,094
Gross Unrealized Gains	31	4
Gross Unrealized Losses	(2,410)	(7,603)
Fair Value	609,238	694,495
Classified as:
Cash equivalents	200,910	107,780
Marketable securities	371,376	516,598
Marketable securities, non-current	36,952	70,117
Total cash equivalents and marketable securities	609,238	694,495
U.S. Treasury securities
Marketable Securities [Line Items]
Amortized Cost	292,610	277,056
Gross Unrealized Gains	31	0
Gross Unrealized Losses	(1,352)	(5,257)
Fair Value	291,289	271,799
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	95,331	135,460
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(820)	(1,416)
Fair Value	94,511	134,045
Corporate debt securities
Marketable Securities [Line Items]
Amortized Cost	106,706	221,608
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(238)	(930)
Fair Value	106,468	220,681
Money market funds
Marketable Securities [Line Items]
Amortized Cost	116,970	67,970
Fair Value	$ 116,970	$ 67,970

Cash Equivalents and Marketab_4

Cash Equivalents and Marketable Securities - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Fair value of securities held in a continuous unrealized loss position for less than twelve months	$ 261.7	$ 287.8
Fair value of securities held in a continuous unrealized loss position for greater than twelve months	$ 101.2	$ 278.7
Maximum
Marketable Securities [Line Items]
Maturity of marketable securities	2 years	2 years

Other Investments (Details)

Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Oct. 01, 2022
Schedule of Investments [Line Items]
Other investments	$ 32,001		$ 32,001			$ 44,924
Impairment of other investments	2,923	$ 0	12,923	$ 0
PACT
Schedule of Investments [Line Items]
Preferred stock at fair value							$ 2,900
Other Investment
Schedule of Investments [Line Items]
Other investments					$ 10,000
Cumulative impairments of strategic investments	17,900		17,900			$ 5,000
Impairment of other investments			10,000
Other Investment | PACT
Schedule of Investments [Line Items]
Preferred stock at fair value							$ 2,900
Impairment of other investments	$ 2,900		$ 2,900

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financial assets:
Total financial assets	$ 609,238	$ 694,495
Financial liabilities:
Success payment liabilities	3,753	4,356
Total financial liabilities	3,753	4,356
U.S. Treasury securities
Financial assets:
Marketable securities	291,289	271,799
U.S. government agency securities
Financial assets:
Marketable securities	94,511	134,045
Corporate debt securities
Financial assets:
Marketable securities	106,468	220,681
Money market funds
Financial assets:
Money market funds	116,970	67,970
Level 1
Financial assets:
Total financial assets	116,970	67,970
Financial liabilities:
Success payment liabilities	0	0
Total financial liabilities	0	0
Level 1 | U.S. Treasury securities
Financial assets:
Marketable securities	0	0
Level 1 | U.S. government agency securities
Financial assets:
Marketable securities	0	0
Level 1 | Corporate debt securities
Financial assets:
Marketable securities	0	0
Level 1 | Money market funds
Financial assets:
Money market funds	116,970	67,970
Level 2
Financial assets:
Total financial assets	492,268	626,525
Financial liabilities:
Success payment liabilities	0	0
Total financial liabilities	0	0
Level 2 | U.S. Treasury securities
Financial assets:
Marketable securities	291,289	271,799
Level 2 | U.S. government agency securities
Financial assets:
Marketable securities	94,511	134,045
Level 2 | Corporate debt securities
Financial assets:
Marketable securities	106,468	220,681
Level 2 | Money market funds
Financial assets:
Money market funds	0	0
Level 3
Financial assets:
Total financial assets	0	0
Financial liabilities:
Success payment liabilities	3,753	4,356
Total financial liabilities	3,753	4,356
Level 3 | U.S. Treasury securities
Financial assets:
Marketable securities	0	0
Level 3 | U.S. government agency securities
Financial assets:
Marketable securities	0	0
Level 3 | Corporate debt securities
Financial assets:
Marketable securities	0	0
Level 3 | Money market funds
Financial assets:
Money market funds	$ 0	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Estimated Fair Value of Success Payment Liability Assumptions (Details)	Jun. 30, 2023 $ / shares	Dec. 31, 2022 $ / shares
Fred Hutch
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of common stock Series A convertible preferred stock	$ 3.18	$ 3.47
Fred Hutch | Risk-free interest rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	3.36	3.58
Fred Hutch | Risk-free interest rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	5.26	4.65
Fred Hutch | Expected volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	0.800	0.800
Fred Hutch | Expected term (in years) | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	0.96	0.46
Fred Hutch | Expected term (in years) | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	4.47	4.97
Stanford
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of common stock Series A convertible preferred stock	$ 3.18	$ 3.47
Stanford | Risk-free interest rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	3.36	3.58
Stanford | Risk-free interest rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	5.26	4.65
Stanford | Expected volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	0.800	0.800
Stanford | Expected term (in years) | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	0.96	0.46
Stanford | Expected term (in years) | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Success payment liability, measurement input (as a percent)	6.25	6.75

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Changes in Estimated Fair Value of Financial Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Fred Hutch | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Success Payment Liabilities
Success payment expense (gain)	$ 500	$ 2,200	$ (600)	$ (600)
Stanford | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Success Payment Liabilities
Success payment expense (gain)	600	$ 1,400	0	$ 400
Success Payment Liabilities | Level 3
Success Payment Liabilities
Beginning Balance			4,356
Change in fair value			(603)
Ending Balance	$ 3,753		$ 3,753

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Oct. 01, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of other investments	$ 2,923	$ 0	$ 12,923	$ 0
PACT
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock at fair value					$ 2,900
Other Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of other investments			10,000
Other Investment | PACT
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock at fair value					$ 2,900
Impairment of other investments	$ 2,900		$ 2,900

Leases - Summary of Operating L

Leases - Summary of Operating Lease Commitments Including Expected Lease Incentives to be Received (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Leases [Abstract]
2023 (remaining six months)	$ 5,630
2024	11,347
2025	11,859
2026	12,209
2027	12,569
Thereafter	35,525
Total undiscounted lease payments	89,139
Less: imputed interest	(23,065)
Total operating lease liabilities	66,074
Operating Lease Liability
Short-term portion of lease liabilities (included in accrued liabilities and other current liabilities)	5,853
Operating lease liabilities, non-current	60,221	$ 63,168
Total	$ 66,074

Leases - Narrative (Details)

Leases - Narrative (Details) ft² in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022	Sep. 30, 2021 USD ($) ft²	May 31, 2021 ft²
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 2,300	$ 2,200	$ 4,400	$ 4,700
Variable lease cost	$ 1,400	1,200	$ 2,800	2,500
Weighted average remaining lease term of operating leases	7 years 3 months 18 days		7 years 3 months 18 days		7 years 9 months 18 days
Operating lease, weighted average discount rate (as a percent)	8.50%		8.50%		8.50%
South San Francisco, California
Lessee, Lease, Description [Line Items]
Rentable area | ft²							11
Sublease income	$ 200	200	$ 400	400
Related Party
Lessee, Lease, Description [Line Items]
Rentable area | ft²						18
Related Party | Sonoma
Lessee, Lease, Description [Line Items]
Rentable area | ft²						18
Sublease income	$ 464	$ 466	$ 930	$ 931
Tenant improvements						$ 4,600

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($)	Aug. 04, 2022	Jun. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Preferred stock authorized (in shares)		10,000,000	10,000,000
Preferred stock, par value (in dollars per share)		$ 0.0001	$ 0.0001
Preferred stock outstanding (in shares)		0	0
Common stock authorized (in shares)		500,000,000	500,000,000
Common stock, par value (in dollars per share)		$ 0.0001	$ 0.0001
Common stock outstanding (in shares)		251,026,997	249,567,343
Goldman Sachs and BofA | At The Market Offering | Equity Distribution Agreement
Class of Stock [Line Items]
Aggregate offering amount	$ 200,000,000
Percentage of commission from each sale of shares	3%

Stock-based Compensation - Narr

Stock-based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 01, 2023	Jun. 30, 2021	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation cost related to unvested awards not yet recognized			$ 81.6		$ 81.6
Expected weighted-average period compensation cost to be recognized					2 years 10 months 9 days
Weighted average grant date fair value (in dollars per share)					$ 1.72	$ 4.27
2021 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for future issuance (in shares)		26,662,087
Award expiration period		10 years
Proportion of stock outstanding (as a percent)		5%
Number of additional shares authorized for issuance (in shares)	12,478,367
Increase in proportion of common shares reserved for future issuance (as a percent)	5%
Vesting period		4 years
Future issuance of common shares (in shares)			25,280,983		25,280,983
Stock-based compensation (in shares)			542,921	283,574	542,921	283,574
2021 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period		10 years
2021 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for future issuance (in shares)		2,470,000
Award expiration period		10 years
Proportion of stock outstanding (as a percent)		1%
Future issuance of common shares (in shares)			3,905,099		3,905,099
Purchase of common stock at discount (as a percent)		15%
Employee purchase of shares, proportion of fair value (as a percent)		85%
Maximum number of shares to be purchased under ESPP (in shares)		4,940,000
Maximum offering period		27 months
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period							10 years
Vesting period							4 years
Future issuance of common shares (in shares)							0

Stock-based Compensation - Sche

Stock-based Compensation - Schedule of Stock-Based Compensation Expense by Classification (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 14,223	$ 22,410	$ 28,105	$ 44,438
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	5,279	4,195	9,891	7,959
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 8,944	$ 18,215	$ 18,214	$ 36,479

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock Units (Details) - RSUs	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Restricted Stock Units Outstanding
Balance at beginning of period (in shares) | shares	872,077
RSUs granted (in shares) | shares	1,997,177
RSUs vested (in shares) | shares	(127,886)
RSUs forfeited or canceled (in shares) | shares	(117,669)
Balance at end of period (in shares) | shares	2,623,699
Weighted-Average Value at Grant Date Per Share
Balance at beginning of period (in dollars per share) | $ / shares	$ 5.98
RSUs granted (in dollars per share) | $ / shares	2.16
RSUs vested (in dollars per share) | $ / shares	5.98
RSUs forfeited or canceled (in dollars per share) | $ / shares	4.28
Balance at end of period (in dollars per share) | $ / shares	$ 3.15

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Number of Stock Options
Beginning balance (in shares) | shares	53,849,045
Granted (in shares) | shares	8,586,063
Exercised (in shares) | shares	(832,840)
Canceled or forfeited (in shares) | shares	(2,959,671)
Ending balance (in shares) | shares	58,642,597	53,849,045
Exercisable (in shares) | shares	30,365,614
Weighted- Average Exercise Price Per Share
Beginning balance (in dollars per share) | $ / shares	$ 5.09
Granted (in dollars per share) | $ / shares	2.23
Exercised (in dollars per share) | $ / shares	0.10
Cancelled or forfeited (in dollars per share) | $ / shares	5.12
Ending balance (in dollars per share) | $ / shares	4.74	$ 5.09
Exercisable (in dollars per share) | $ / shares	$ 4.77
Weighted- Average Remaining Contractual Life (in years)
Options Outstanding	7 years 8 months 23 days	7 years 10 months 2 days
Options Exercisable	6 years 7 months 9 days
Aggregate Intrinsic Value (in thousands)
Options Outstanding | $	$ 26,401	$ 24,887
Options Exercisable | $	$ 18,878

Stock-based Compensation - Sc_2

Stock-based Compensation - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model for Estimating Fair Value of Stock Options Granted (Details)	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Share-Based Payment Arrangement [Abstract]
Risk-free interest rate	4.09%	2.28%
Expected volatility	92.40%	85.50%
Expected term (in years)	5 years 11 months 26 days	5 years 11 months 23 days
Expected dividend yield	0%	0%

Related-party Transactions - Na

Related-party Transactions - Narrative (Details) ft² in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2021 USD ($) ft²
Related Party Transaction [Line Items]
Accrued liabilities and other current liabilities	$ 24,832		$ 24,832		$ 28,755
Other non-current liabilities	3,888		3,888		4,113
Related Party
Related Party Transaction [Line Items]
Rentable area | ft²						18
Related Party | Sonoma
Related Party Transaction [Line Items]
Rentable area | ft²						18
Tenant improvements						$ 4,600
Accrued liabilities and other current liabilities	500		500		500
Other non-current liabilities	3,300		3,300		3,500
Related Party | GSK
Related Party Transaction [Line Items]
Contract liabilities	0		0		$ 0
Revenue recognized	$ 0	$ 35,700	$ 0	$ 36,300
Related Party | Minimum | Lyell Immunopharma | GSK
Related Party Transaction [Line Items]
Ownership interest (as a percent)	10%		10%

Related-party Transactions - Sc

Related-party Transactions - Schedule of Total Income Attributable to Sonoma Sublease (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Related Party Transaction [Line Items]
Other operating income, net	$ 569	$ 1,171	$ 1,857	$ 2,293
Related Party | Sonoma
Related Party Transaction [Line Items]
Other operating income, net	648	658	1,317	1,317
Sublease income	$ 464	$ 466	$ 930	$ 931