Erasca (ERAS) 10-K 27 Mar 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Mar. 21, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	ERASCA, INC.
Entity Central Index Key	0001761918
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity File Number	001-40602
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-1217027
Entity Address, Address Line One	3115 Merryfield Row
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	465-6511
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		151,494,161
Entity Public Float			$ 297
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	ERAS
Security Exchange Name	NASDAQ
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	false
Auditor Firm ID	185
Auditor Name	KPMG LLP
Auditor Location	San Diego, California
Documents Incorporated by Reference [Text Block]	Certain sections of the Registrant’s definitive proxy statement for the 2024 annual meeting of stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Form 10-K are incorporated by reference into Part III of this Form 10-K.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 93,075,000	$ 284,217,000
Short-term marketable securities	219,275,000	151,403,000
Prepaid expenses and other current assets	8,326,000	8,876,000
Total current assets	320,676,000	444,496,000
Long-term marketable securities	9,642,000
Property and equipment, net	22,327,000	24,815,000
Operating lease assets	37,861,000	40,418,000
Restricted cash	408,000	408,000
Other assets	4,383,000	4,772,000
Total assets	395,297,000	514,909,000
Current liabilities:
Accounts payable	2,000,000	23,049,000
Accrued expenses and other current liabilities	20,186,000	24,336,000
Operating lease liabilities	3,970,000	1,305,000
Total current liabilities	26,156,000	48,690,000
Operating lease liabilities, net of current portion	51,889,000	53,793,000
Other liabilities	566,000	573,000
Total liabilities	78,611,000	103,056,000
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock, $0.0001 par value; 80,000,000 shares authorized at December 31, 2023 and 2022; no shares issued and outstanding at December 31, 2023 and 2022
Common stock, $0.0001 par value; 800,000,000 shares authorized at December 31, 2023 and 2022; 151,462,103 and 150,448,363 shares issued at December 31, 2023 and 2022, respectively; 151,090,227 and 149,333,258 shares outstanding at December 31, 2023 and 2022, respectively	15,000	15,000
Additional paid-in capital	922,607,000	893,850,000
Accumulated other comprehensive income (loss)	77,000	(1,041,000)
Accumulated deficit	(606,013,000)	(480,971,000)
Total stockholders' equity	316,686,000	411,853,000
Total liabilities and stockholders' equity	$ 395,297,000	$ 514,909,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	80,000,000	80,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	151,462,103	150,448,363
Common stock, shares outstanding	151,090,227	149,333,258

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating expenses:
Research and development	$ 103,821	$ 112,457
In-process research and development		102,000
General and administrative	37,704	32,993
Total operating expenses	141,525	247,450
Loss from operations	(141,525)	(247,450)
Other income (expense)
Interest income	16,712	4,902
Other expense, net	(229)	(257)
Total other income (expense), net	16,483	4,645
Net loss	$ (125,042)	$ (242,805)
Net loss per share, basic	$ (0.83)	$ (1.99)
Net loss per share, diluted	$ (0.83)	$ (1.99)
Weighted-average shares of common stock used in computing net loss per share, basic	150,184,994	122,024,848
Weighted-average shares of common stock used in computing net loss per share, diluted	150,184,994	122,024,848
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities, net	$ 1,118	$ (879)
Comprehensive loss	$ (123,924)	$ (243,684)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	2022 Underwritten Offering	Common Stock	Common Stock 2022 Underwritten Offering	Additional Paid-in Capital	Additional Paid-in Capital 2022 Underwritten Offering	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance, shares at Dec. 31, 2021			121,382,547
Beginning balance at Dec. 31, 2021	$ 456,528		$ 12		$ 694,844		$ (162)	$ (238,166)
Issuance of common stock in connection with license agreement, shares			12,307,692
Issuance of common stock in connection with license agreement	80,000		$ 1		79,999
Issuance of common stock, net of discounts and issuance costs, Shares				15,384,616
Issuance of common stock, net of discounts and issuance costs		$ 94,883		$ 2		$ 94,881
Exercise of stock options, shares			1,177,571
Exercise of stock options	2,004				2,004
Issuance of common stock under the Employee Stock Purchase Plan, Shares			202,882
Issuance of common stock under the Employee Stock Purchase Plan	820				820
Vesting of early exercised stock options	1,193				1,193
Repurchases of restricted stock			(6,945)
Stock-based compensation expense	20,109				20,109
Net Income (Loss)	(242,805)							(242,805)
Unrealized loss on marketable securities, net	$ (879)						(879)
Ending balance, shares at Dec. 31, 2022	150,448,363		150,448,363
Ending balance at Dec. 31, 2022	$ 411,853		$ 15		893,850		(1,041)	(480,971)
Exercise of stock options, shares			624,807
Exercise of stock options	505				505
Issuance of common stock under the Employee Stock Purchase Plan, Shares			388,933
Issuance of common stock under the Employee Stock Purchase Plan	790				790
Vesting of early exercised stock options	1,231				1,231
Stock-based compensation expense	26,231				26,231
Net Income (Loss)	(125,042)							(125,042)
Unrealized loss on marketable securities, net	$ 1,118						1,118
Ending balance, shares at Dec. 31, 2023	151,462,103		151,462,103
Ending balance at Dec. 31, 2023	$ 316,686		$ 15		$ 922,607		$ 77	$ (606,013)

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Common Stock | Underwritten Offering
Discounts and offering costs	$ 5,117

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (125,042)	$ (242,805)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,732	2,641
Stock-based compensation expense	26,231	20,109
In-process research and development		102,000
Accretion on marketable securities, net	(6,951)	(994)
Changes in operating assets and liabilities:
Prepaid expenses and other current and long-term assets	939	(3,612)
Accounts payable	(886)	676
Accrued expenses and other current and long-term liabilities	(2,301)	5,018
Operating lease assets and liabilities, net	3,061	13,703
Net cash used in operating activities	(101,217)	(103,264)
Cash flows from investing activities:
Purchases of marketable securities	(314,390)	(132,330)
Maturities of marketable securities	244,945	79,800
In-process research and development	(20,000)	(2,000)
Payment made for investment in equity securities		(2,000)
Purchases of property and equipment, net	(1,775)	(14,551)
Net cash used in investing activities	(91,220)	(71,081)
Cash flows from financing activities:
Proceeds from the issuance of common stock in underwritten offering, net of discounts and offering costs		95,251
Proceeds from the exercise of stock options	505	2,004
Proceeds from issuance of common stock under the Employee Stock Purchase Plan	790	820
Net cash provided by financing activities	1,295	98,075
Net decrease in cash, cash equivalents and restricted cash	(191,142)	(76,270)
Cash, cash equivalents and restricted cash at beginning of the period	284,625	360,895
Cash, cash equivalents and restricted cash at end of the period	93,483	284,625
Supplemental disclosure of noncash investing and financing activity:
Issuance of common stock in connection with license agreement		80,000
Amounts accrued for in-process research and development expenses		20,000
Amounts accrued for purchases of property and equipment	13	800
Amounts accrued for offering costs		368
Vesting of early exercised options	$ 1,231	1,193
Operating lease assets obtained in exchange for lease obligation		22,704
Reduction in operating lease assets due to lease amendment		$ 3,361

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (125,042)	$ (242,805)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 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
Non-Rule 10b5-1 Arrangement Modified	false
Rule 10b5-1 Arrangement Modified	false

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Note 1. Organization and basis of presentation Organization and nature of operations Erasca, Inc. (Erasca or the Company) is a clinical-stage precision oncology company singularly focused on discovering, developing, and commercializing therapies for RAS/MAPK pathway-driven cancers. The Company has assembled a wholly-owned or controlled RAS/MAPK pathway-focused pipeline which is focused on modality-agnostic programs aligned with its three therapeutic strategies of: (1) targeting key upstream and downstream signaling nodes in the RAS/MAPK pathway; (2) targeting RAS directly; and (3) targeting escape routes that emerge in response to treatment. The Company was incorporated under the laws of the State of Delaware on July 2, 2018, as Erasca, Inc., and is headquartered in San Diego, California. In September 2020, the Company established a wholly-owned Australian subsidiary, Erasca Australia Pty Ltd (Erasca Australia), in order to conduct clinical activities in Australia for its development candidates. In November 2020, the Company entered into an agreement and plan of merger with Asana BioSciences, LLC (Asana) and ASN Product Development, Inc. (ASN) (the Asana Merger Agreement), pursuant to which ASN became the Company's wholly-owned subsidiary. In March 2021, the Company established a wholly-owned subsidiary, Erasca Ventures, LLC (Erasca Ventures), to make equity investments in early-stage biotechnology companies that are aligned with the Company’s mission and strategy. Since inception, the Company has devoted substantially all of its efforts and resources to organizing and staffing the Company, business planning, raising capital, identifying, acquiring and in-licensing the Company’s product candidates, establishing its intellectual property portfolio, conducting research, preclinical studies, and clinical trials, establishing arrangements with third parties for the manufacture of its product candidates and related raw materials, and providing general and administrative support for these operations. As of December 31, 2023, the Company had $ 312.4 million in cash, cash equivalents, and short-term marketable securities, and $ 9.6 million in long-term marketable securities. As of December 31, 2023, the Company had an accumulated deficit of $ 606.0 million. The Company has incurred significant operating losses and negative cash flows from operations. From its inception through December 31, 2023, the Company’s financial support has primarily been provided from the sale of its convertible preferred stock and the sale of its common stock in its initial public offering (IPO) and underwritten offering (2022 Offering). The Company expects to use its cash, cash equivalents, and marketable securities to fund research and development, working capital, and other general corporate purposes. The Company does not expect to generate any revenues from product sales unless and until the Company successfully completes development and obtains regulatory approval for any of its product candidates, which will not be for at least the next several years, if ever. Accordingly, until such time as the Company can generate significant revenue from sales of its product candidates, if ever, the Company expects to finance its cash needs through equity offerings, debt financings, or other capital sources, including potential collaborations, licenses or other similar arrangements. However, the Company may not be able to secure additional financing or enter into such other arrangements in a timely manner or on favorable terms, if at all. The Company’s failure to raise capital or enter into such other arrangements when needed would have a negative impact on the Company’s financial condition and could force the Company to delay, limit, reduce or terminate its research and development programs or other operations, or grant rights to develop and market product candidates that the Company would otherwise prefer to develop and market itself. The Company believes its cash, cash equivalents, and marketable securities as of December 31, 2023 will be sufficient for the Company to fund operations for at least one year from the issuance date of these consolidated financial statements. Underwritten offering In December 2022, the Company completed the 2022 Offering pursuant to which the Company issued and sold 15,384,616 shares of its common stock at a price to the public of $ 6.50 per share. Proceeds from the offering were $ 94.9 million, net of underwriting discounts and commissions and offering costs of $ 5.1 million. Basis of presentation The accompanying consolidated financial statements have been prepared in accordance with US generally accepted accounting principles (US GAAP). Any reference in these notes to applicable guidance is meant to refer to US GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASU) promulgated by the Financial Accounting Standards Board (FASB). Principles of consolidation and foreign currency transactions The Company’s consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Erasca Australia, ASN, and Erasca Ventures. Erasca Australia was registered under the laws of Australia on September 1, 2020, ASN was incorporated under the laws of the State of Delaware on November 23, 2020, and Erasca Ventures was formed under the laws of the State of Delaware on March 30, 2021. All intercompany balances and transactions have been eliminated. The functional currency of the Company and its wholly-owned subsidiaries is the US dollar. Assets and liabilities that are not denominated in the functional currency are remeasured into US dollars at foreign currency exchange rates in effect at the balance sheet date except for nonmonetary assets, which are remeasured at historical foreign currency exchange rates in effect at the date of transaction. Net realized and unrealized gains and losses from foreign currency transactions and remeasurement are reported in other income (expense), in the consolidated statements of operations and comprehensive loss and were not material for all periods presented.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of significant accounting policies Use of estimates The preparation of the Company’s consolidated financial statements in conformity with US GAAP requires the Company to make estimates and assumptions that impact the reported amounts of assets, liabilities, expenses, and the disclosure of contingent assets and liabilities in the consolidated financial statements and accompanying notes. Accounting estimates and management judgments reflected in the consolidated financial statements include, but are not limited to, the accrual of research and development expenses, stock-based compensation expense, and the incremental borrowing rate for determining the operating lease asset and liability. Management evaluates its estimates on an ongoing basis. Although estimates are based on the Company’s historical experience, knowledge of current events, and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Concentration of credit risk and off-balance sheet risk Financial instruments which potentially subject the Company to significant concentration of credit risk consist of cash and cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts, and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company’s investment policy includes guidelines for the quality of the related institutions and financial instruments and defines allowable investments that the Company may invest in, which the Company believes minimizes the exposure to concentration of credit risk. Cash, cash equivalents and restricted cash Cash and cash equivalents include cash in readily available checking and savings accounts, and money market funds. The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents. The Company had deposited cash of $ 408,000 as of December 31, 2023 and 2022 to secure a letter of credit in connection with the lease of the Company’s facilities (see Note 11). The Company has classified the restricted cash as a noncurrent asset on its consolidated balance sheets. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same amounts shown in the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 93,075 $ 284,217 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 93,483 $ 284,625 Marketable securities and investments The Company classifies all marketable securities as available-for-sale, as the sale of such securities may be required prior to maturity. Management determines the appropriate classification of its marketable securities at the time of purchase. Marketable securities with original maturities beyond three months at the date of purchase and which mature at, or less than 12 months from, the balance sheet date are classified as short-term marketable securities. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized. The amortized cost of available-for-sale debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. The Company regularly reviews all of its marketable securities for declines in fair value. The review includes the consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity of the unrealized loss(es), whether the Company has the intent to sell the securities and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. If the decline in fair value is due to credit-related factors, a loss is recognized in net income; whereas, if the decline in fair value is not due to credit-related factors, the loss is recorded in other comprehensive income (loss). Realized gains and losses on available-for-sale securities are included in other income or expense. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. Through its wholly-owned subsidiary, Erasca Ventures, the Company has also invested in equity securities of a company whose securities are not publicly traded and whose fair value is not readily available (see Notes 3 and 17). This investment is recorded using cost minus impairment, plus or minus changes in its estimated fair value resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Investments in equity securities without readily determinable fair values are assessed for potential impairment on a quarterly basis based on qualitative factors. This investment is included in other assets in the Company's consolidated balance sheets. Fair value measurements Certain assets and liabilities are carried at fair value under US GAAP. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: Level 1—Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2—Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability. Level 3—Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Property and equipment, net Property and equipment are stated at cost less accumulated depreciation. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years . Leasehold improvements are amortized over the shorter of the estimated useful lives of the assets or the remaining lease term. Impairment of long-lived assets The Company continually evaluates long-lived assets for potential impairment when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparing the book values of the assets to the expected future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book values of the assets exceed their fair value. The Company did no t recognize any impairment losses for the years ended December 31, 2023 and 2022 . Leases The Company leases real estate facilities and equipment under non-cancelable and cancelable operating leases with various expiration dates through fiscal year 2032. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. Operating leases are included in operating lease assets and in operating lease liabilities in the accompanying consolidated balance sheets. Operating lease assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term discounted based on the more readily determinable of (i) the rate implicit in the lease or (ii) the Company’s incremental borrowing rate (which is the estimated rate the Company would be required to pay for a collateralized borrowing equal to the total lease payments over the term of the lease). Because the Company’s operating leases generally do not provide an implicit rate, the Company estimates its incremental borrowing rate based on the information available at lease commencement date for borrowings with a similar term. The Company’s operating lease assets are measured based on the corresponding operating lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs incurred and (iii) tenant incentives under the lease. The Company does not assume renewals or early terminations unless it is reasonably certain to exercise these options at commencement. The Company elected the practical expedient which allows the Company to not allocate consideration between lease and non-lease components. Variable lease payments are recognized in the period in which the obligations for those payments are incurred. In addition, the Company elected the practical expedient such that it does not recognize lease assets or lease liabilities for leases with a term of 12 months or less for all asset classes. Operating lease expense is recognized on a straight-line basis over the lease term. Certain of the Company's real estate leases include tenant improvement allowances, which are recognized as lease incentives and amortized on a straight-line basis over the lease term as an offset to rent expense. Research and development expense Research and development expenses consist of external and internal costs associated with the Company’s research and development activities, including its discovery and research efforts and the preclinical and clinical development of its product candidates. Research and development costs are expensed as incurred. The Company’s research and development expenses include external costs, consisting of expenses incurred under arrangements with third parties, such as contract research organizations (CROs), contract manufacturing organizations (CMOs), consultants and its scientific advisors; and internal costs, consisting of employee-related expenses, including salaries, benefits, and stock-based compensation for those individuals involved in research and development efforts, the costs of laboratory supplies and acquiring, developing and manufacturing preclinical study materials, and facilities and depreciation, which include direct and allocated expenses for rent of facilities and depreciation. The Company records accruals for estimated research and development costs, comprising payments for work performed by third party contractors, laboratories, and others. Some of these contractors bill monthly based on actual services performed, while others bill periodically based upon achieving certain contractual milestones. For the latter, the Company accrues the expenses as goods or services are used or rendered. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized as prepaid expenses until the related goods are delivered or services are performed. In-process research and development expense The Company has acquired rights as part of asset acquisitions or in-licenses to develop and commercialize product candidates. Upfront payments that relate to the acquisition of a new product candidate, as well as pre-commercial milestone payments, are immediately expensed as in-process research and development (IPR&D) in the period in which they are incurred, provided that the new product candidate did not also include processes or activities that would constitute a “business” as defined under US GAAP, the product candidate has not achieved regulatory approval for marketing and, absent obtaining such approval, has no established alternative future use. The Company accounts for contingent consideration payable upon achievement of certain regulatory, development or sales milestones in such asset acquisitions when the underlying contingency is probable and estimable. Milestone payments made to third parties subsequent to regulatory approval will be capitalized as intangible assets and amortized over the estimated remaining useful life of the related product. Patent costs The Company expenses all costs as incurred in connection with patent applications (including direct application fees, and the legal and consulting expenses related to making such applications) and such costs are included in general and administrative expenses in the consolidated statements of operations and comprehensive loss. Stock-based compensation The Company measures employee and nonemployee stock-based awards based on the fair value on the date of grant and records compensation expense on a straight-line basis over the requisite service period of the award. All stock-based compensation costs are recorded in the consolidated statements of operations and comprehensive loss based upon the underlying employees' or nonemployees' roles within the Company. Forfeitures are accounted for as they occur. The fair value of stock option grants and shares purchasable under the Company's 2021 Employee Stock Purchase Plan (ESPP) is estimated on the date of grant using the Black-Scholes options-pricing model, which requires inputs based on certain subjective assumptions, including the: • Risk-free interest rate. The risk-free interest rate is based on the US Treasury zero-coupon issues in effect at the time of grant for periods corresponding with the expected term of the stock-based awards. • Expected volatility. Given that the Company’s common stock was privately held prior to the IPO, there was no active trading market for its common stock. The Company derived the expected volatility from the average historical volatilities over a period approximately equal to the expected term of comparable publicly traded companies within its peer group that were deemed to be representative of future stock price trends. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. • Expected term. The expected term represents the period that the stock-based awards are expected to be outstanding. The expected term of stock options issued is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term) as the Company has concluded that its stock option exercise history does not provide a reasonable basis upon which to estimate expected term. • Expected dividend yield. The Company has never paid dividends on its common stock and does not anticipate paying any dividends in the foreseeable future. Therefore, the Company used an expected dividend yield of zero . The fair value of each restricted common stock award is estimated on the date of grant based on the fair value of the Company’s common stock on that same date. Income taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s consolidated financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. As of December 31, 2023 , the Company’s tax years since inception are subject to examination by taxing authorities due to the Company’s unutilized net operating losses and tax credits. Comprehensive income (loss) The Company reports all components of comprehensive income (loss), including net loss, in the consolidated financial statements in the period in which they are recognized. Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities. Other comprehensive income (loss) includes unrealized gains and losses on marketable securities, which was the only difference between net loss and comprehensive loss for the applicable periods. Net loss per share The Company’s net loss is equivalent to net loss attributable to common stockholders for all periods presented. Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, options to purchase common stock, shares purchasable under the ESPP and common stock subject to repurchase related to options early exercised are considered to be potentially dilutive securities. Basic and diluted net loss per share is presented in conformity with the two-class method required for participating securities as the shares issued upon the early exercise of stock options subject to repurchase are considered to be participating securities because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. The Company’s participating securities do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. As the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. Segments The Company has determined that its chief executive officer is the chief operating decision maker (CODM). The Company operates and manages the business as one reporting and one operating segment, which is the business of discovering and developing precision medicines for the benefit of patients with cancer. The Company’s CODM reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s assets are located in the United States. Recently adopted accounting pronouncements There were no accounting pronouncements adopted by the Company during the year ended December 31, 2023. Recently issued accounting pronouncements not yet adopted From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act) and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company can adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which is intended to provide enhancements to segment disclosures, even for entities with only one reportable segment. In particular, the standard will require disclosures of significant segment expenses regularly provided to the chief operating decision maker and included within each reported measure of segment profit and loss. The standard will also require disclosure of all other segment items by reportable segment and a description of its composition. Finally, the standard will require disclosure of the title and position of the chief operating decision maker and an explanation of how the chief operating decision maker uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. The standard is effective for annual periods beginning after December 15, 2023, and interim periods within annual periods beginning after December 15, 2024. Early adoption is permitted. Retrospective application to all prior periods presented in the financial statements is required. The Company is currently evaluating the impact of the standard on the presentation of its consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which is intended to provide enhancements to annual income tax disclosures. In particular, the standard will require more detailed information in the income tax rate reconciliation, as well as the disclosure of income taxes paid disaggregated by jurisdiction, among other enhancements. The standard is effective for the Company in its annual period beginning after December 15, 2025 and early adoption is permitted. The standard allows for adoption on a prospective basis, with a retrospective option. The Company is currently evaluating the impact of the standard on the presentation of its consolidated financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 3. Fair value measurements The following tables summarize the Company’s financial assets measured at fair value on a recurring basis and their respective input levels based on the fair value hierarchy (in thousands): Fair value measurements as of December 31, 2023 using Quoted prices in Significant Significant active markets other unobservable December 31, for identical observable inputs 2023 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 83,101 $ 83,101 $ — $ — US treasury securities (2) 93,303 93,303 — — US government agency securities (2) 26,824 — 26,824 — Corporate debt securities (2) 10,734 — 10,734 — Commercial paper (2) 88,414 — 88,414 — US treasury securities (3) 9,642 9,642 — — Total fair value of assets $ 312,018 $ 186,046 $ 125,972 $ — (1) Included as cash and cash equivalents on the consolidated balance sheets. (2) Included as short-term marketable securities on the consolidated balance sheets. (3) Included as long-term marketable securities on the consolidated balance sheets. Fair value measurements as of December 31, 2022 using Quoted prices in Significant Significant active markets other unobservable December 31, for identical observable inputs 2022 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 255,080 $ 255,080 $ — $ — US treasury securities (2) 127,476 127,476 — — US government agency securities (2) 1,468 — 1,468 — Corporate debt securities (2) 3,301 — 3,301 — Commercial paper (2) 18,519 — 18,519 — Supranational debt securities (2) 639 — 639 — Total fair value of assets $ 406,483 $ 382,556 $ 23,927 $ — (1) Included as cash and cash equivalents on the consolidated balance sheets. (2) Included as short-term marketable securities on the consolidated balance sheets. The carrying amounts of the Company’s financial instruments, including cash, prepaid expenses and other current assets, accounts payable, and accrued expenses and other current liabilities, approximate fair value due to their short maturities. As of December 31, 2023 and 2022 , the Company held a $ 2.0 million equity investment in Affini-T Therapeutics, Inc. (Affini-T) at cost. No adjustments have been made to the value of the Company’s investment in Affini-T since its initial measurement either due to impairment or based on observable price changes. None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented. Cash equivalents consist of money market funds, short-term marketable securities consist of US treasury securities, US government agency securities, corporate debt securities, commercial paper, and supranational debt securities, and long-term marketable securities consist of US treasury securities. The Company obtains pricing information from its investment manager and generally determines the fair value of marketable securities usi ng standard observable inputs, including benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, and bid and/or offers.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	Note 4. Marketable securities The following tables summarize the Company’s marketable securities accounted for as available-for-sale securities (in thousands, except years): December 31, 2023 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 93,377 $ 74 $ ( 148 ) $ 93,303 US government agency securities 1 or less 26,783 45 ( 4 ) 26,824 Corporate debt securities 1 or less 10,719 15 — 10,734 Commercial paper 1 or less 88,356 68 ( 10 ) 88,414 US treasury securities 1 - 2 9,605 37 — 9,642 Total $ 228,840 $ 239 $ ( 162 ) $ 228,917 December 31, 2022 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 128,504 $ 5 $ ( 1,033 ) $ 127,476 US government agency securities 1 or less 1,467 1 — 1,468 Corporate debt securities 1 or less 3,309 — ( 8 ) 3,301 Commercial paper 1 or less 18,519 — — 18,519 Supranational debt securities 1 or less 645 — ( 6 ) 639 Total $ 152,444 $ 6 $ ( 1,047 ) $ 151,403 The following tables present fair values and gross unrealized losses for those available-for-sale securities that were in an unrealized loss position as of December 31, 2023 and 2022, aggregated by category and the length of time that the securities have been in a continuous loss position (in thousands): December 31, 2023 Unrealized losses less than 12 months Unrealized losses 12 months or greater Total Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses US treasury securities $ 74,912 $ ( 148 ) $ — $ — $ 74,912 $ ( 148 ) US government agency securities 6,950 ( 4 ) — — 6,950 ( 4 ) Corporate debt securities 748 — — — 748 — Commercial paper 22,944 ( 10 ) — — 22,944 ( 10 ) Total $ 105,554 $ ( 162 ) $ — $ — $ 105,554 $ ( 162 ) December 31, 2022 Unrealized losses less than 12 months Unrealized losses 12 months or greater Total Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses US treasury securities $ 60,652 $ ( 129 ) $ 44,048 $ ( 904 ) $ 104,700 $ ( 1,033 ) Corporate debt securities 2,560 ( 8 ) — — 2,560 ( 8 ) Supranational debt securities 639 ( 6 ) — — 639 ( 6 ) Total $ 63,851 $ ( 143 ) $ 44,048 $ ( 904 ) $ 107,899 $ ( 1,047 ) As of December 31, 2023, there were 22 available-for-sale securities with an estimated fair value of $ 105.6 million in gross unrealized loss positions, none of which were in an unrealized loss position for more than 12 months. As of December 31, 2022, there were 35 available-for-sale securities with an estimated fair value of $ 107.9 million in gross unrealized loss positions, of which 10 available-for-sale securities with an estimated fair value of $ 44.0 million were in an unrealized loss position for more than 12 months . As of December 31, 2023 and 2022, unrealized losses on available-for-sale securities are not attributed to credit risk. The Company believes that an allowance for credit losses is unnecessary because the unrealized losses on certain of the Company’s available-for-sale securities are due to market factors and interest rate increases. Additionally, the Company does not intend to sell the securities nor is it more likely than not that the Company will be required to sell the securities before recovery of their amortized cost basis. Accrued interest on the Company’s available-for-sale securities was $ 1.1 million and $ 748,000 as of December 31, 2023 and 2022 , respectively, and is included in prepaid expenses and other current assets on the consolidated balance sheets.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Note 5. Property and equipment, net Property and equipment, net consisted of the following (in thousands): December 31, December 31, 2023 2022 Laboratory equipment $ 5,620 $ 4,815 Furniture and fixtures 4,099 4,104 Leasehold improvements 18,173 17,837 Computer equipment and software 1,667 1,559 Property and equipment 29,559 28,315 Less accumulated depreciation and amortization ( 7,232 ) ( 3,500 ) Property and equipment, net $ 22,327 $ 24,815 Depreciation and amortization expense related to property and equipment was $ 3.7 million and $ 2.6 million for the years ended December 31, 2023 and 2022 , respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Note 6. Accrued expenses and other current liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, December 31, 2023 2022 Accrued research and development expenses $ 8,803 $ 11,523 Accrued compensation 10,311 9,395 Unvested early exercised stock option liability 464 1,690 Accrued professional services 435 873 Accrued property and equipment 13 638 Other accruals 160 217 Total $ 20,186 $ 24,336

Asset Acquisitions

Asset Acquisitions	12 Months Ended
	Dec. 31, 2023
Asset Acquisition [Abstract]
Asset Acquisitions	Note 7. Asset acquisitions The following purchased assets were accounted for as asset acquisitions as substantially all of the fair value of the assets acquired were concentrated in a group of similar assets, and the acquired assets did not have outputs or employees. Because the assets had not yet received regulatory approval, the fair value attributable to these assets was recorded as in-process research and development expenses in the Company’s consolidated statements of operations and comprehensive loss. Asana BioSciences, LLC In November 2020, the Company entered into the Asana Merger Agreement, pursuant to which ASN became its wholly-owned subsidiary. Asana and ASN had previously entered into a license agreement, which was amended and restated prior to the closing of the merger transaction (the Asana License Agreement, and collectively with the Asana Merger Agreement, the Asana Agreements), pursuant to which ASN acquired an exclusive, worldwide license to certain intellectual property rights relating to inhibitors of ERK1 and ERK2 owned or controlled by Asana to develop and commercialize ERAS-007 and certain other related compounds for all applications. Under the Asana Merger Agreement, in 2020, the Company made an upfront payment of $ 20.0 million and issued 4,000,000 shares of its Series B-2 convertible preferred stock to Asana at a value of $ 7.50 per share or a total fair value of equity of $ 30.0 million. In connection with the Company’s IPO, these shares of Series B-2 convertible preferred stock were converted into 3,333,333 shares of the Company’s common stock. The Company is obligated to make future development and regulatory milestone cash payments for a licensed product in an amount of up to $ 90.0 million. Additionally, upon achieving a development milestone related to demonstration of successful proof-of-concept in a specified clinical trial, the Company will also be required to issue 3,888,889 shares of its common stock to Asana. The Company is not obligated to pay royalties on the net sales of licensed products. No IPR&D expense was recorded during the years ended December 31, 2023 and 2022. As of December 31, 2023 and 2022 , no milestones had been accrued as the underlying contingencies were not probable or estimable. Emerge Life Sciences, Pte. Ltd. In March 2021, the Company entered into an asset purchase agreement (ELS Purchase Agreement) with Emerge Life Sciences, Pte. Ltd. (ELS) wherein it purchased all rights, title, and interest (including all patent and other intellectual property rights) to EGFR antibodies directed against the EGFR domain II (EGFR-D2) and domain III (EGFR-D3) as well as a bispecific antibody where one arm is directed against EGFR-D2 and the other is directed against EGFR-D3 (the Antibodies). Under the terms of the ELS Purchase Agreement, in 2021, the Company made an upfront payment of $ 2.0 million and issued to ELS 500,000 shares of the Company’s common stock at a value of $ 3.36 per share or a total fair value of equity of $ 1.7 million. No IPR&D expense was recorded during the years ended December 31, 2023 and 2022 .

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2023
License Agreements [Abstract]
License Agreements	Note 8. License agreements Novartis Pharma AG In December 2022, the Company entered into an exclusive license agreement (as amended, the Novartis Agreement) with Novartis Pharma AG (Novartis) under which the Company was granted an exclusive, worldwide, royalty-bearing license to certain patent and other intellectual property rights owned or controlled by Novartis to develop, manufacture, use, and commercialize naporafenib in all fields of use. The Company has the right to sublicense (through multiple tiers) its rights under the Novartis Agreement, subject to certain limitations and conditions, and is required to use commercially reasonable efforts to commercialize licensed products in certain geographical markets. The license granted under the Novartis Agreement is subject to Novartis’ reserved right to: (i) develop, manufacture, use, and commercialize compounds unrelated to naporafenib under the licensed patent rights and know-how, (ii) use the licensed patent rights and know-how for non-clinical research purposes, and (iii) use the licensed patent rights and know-how to the extent necessary to perform ongoing clinical trials and perform its obligations under existing contracts and under the Novartis Agreement. Under the Novartis Agreement, the Company made an upfront cash payment to Novartis of $ 20.0 million and issued to Novartis 12,307,692 shares of common stock of the Company having an aggregate value of approximately $ 80.0 million. The Company is obligated to make future regulatory milestone payments of up to $ 80.0 million and sales milestone payments of up to $ 200.0 million. The Company is also obligated to pay royalties on net sales of all licensed products, in the low-single digit percentages, subject to certain reductions. The Company recorded $ 0 and $ 100.0 million in IPR&D expense during the years ended December 31, 2023 and 2022, respectively, in connection with the Novartis Agreement. As of December 31, 2023 and 2022 , the Company had recorded $ 0 and $ 20.0 million in accounts payable on the consolidated balance sheets related to the upfront cash payment, respectively. As of December 31, 2023 and 2022 , no milestones are accrued as the underlying contingencies are not probable or estimable. Katmai Pharmaceuticals, Inc. In March 2020, the Company entered into a license agreement (the Katmai Agreement) with Katmai Pharmaceuticals, Inc. (Katmai) under which the Company was granted an exclusive, worldwide, royalty-bearing license to certain patent rights and know-how controlled by Katmai related to the development of small molecule therapeutic and diagnostic products that modulate EGFR and enable the identification, diagnosis, selection, treatment, and/or monitoring of patients for neuro-oncological applications to develop, manufacture, use, and commercialize ERAS-801 and certain other related compounds in all fields of use. Under the Katmai Agreement, the Company made an upfront payment of $ 5.7 million and Katmai agreed to purchase shares of the Company’s Series B-1 convertible preferred stock and Series B-2 convertible preferred stock having an aggregate value of $ 2.7 million. In April 2020, Katmai purchased 356,000 shares of the Company’s Series B-1 convertible preferred stock for $ 1.8 million, and in January 2021, Katmai purchased 118,666 shares of the Company’s Series B-2 convertible preferred stock for $ 0.9 million. In connection with the Company's IPO, these shares of Series B-1 convertible preferred stock and Series B-2 convertible preferred stock were converted into 395,555 shares of the Company's common stock, in the aggregate. The Company is obligated to make future development and regulatory milestone payments of up to $ 26.0 million, of which $ 2.0 million was paid in March 2022, and commercial milestone payments of up to $ 101.0 million. The Company is also obligated to pay tiered royalties on net sales of each licensed product, at rates ranging from the mid- to high-single digit percentages, subject to a minimum annual royalty payment in the low six figures and certain permitted deductions. The Company recorded IPR&D expense of $ 2.0 million in connection with a development milestone payment made during the year ended December 31, 2022 . No IPR&D expense was recorded during the year ended December 31, 2023. As of December 31, 2023 and 2022 , no milestones are accrued as the underlying contingencies are not probable or estimable. NiKang Therapeutics, Inc. In February 2020, the Company entered into a license agreement (the NiKang Agreement) with NiKang Therapeutics, Inc. (NiKang) under which the Company was granted an exclusive, worldwide license to certain intellectual property rights owned or controlled by NiKang related to certain SHP2 inhibitors to develop and commercialize ERAS-601 and certain other related compounds for all applications. Under the NiKang Agreement, in 2020, the Company made an upfront payment of $ 5.0 million to NiKang and reimbursed NiKang $ 0.4 million for certain initial manufacturing costs. In addition, the Company paid $ 7.0 million in 2020 related to the publication of a US patent application that covered the composition of matter of ERAS-601. The Company is also obligated to pay (i) development and regulatory milestone payments in an aggregate amount of up to $ 16.0 million for the first licensed product, of which $ 4.0 million was paid in January 2021, and $ 12.0 million for a second licensed product, and (ii) commercial milestone payments in an aggregate amount of up to $ 157.0 million for the first licensed product and $ 151.0 million for a second licensed product. The Company is also obligated to: (i) pay tiered royalties on net sales of all licensed products in the mid-single digit percentages, subject to certain reductions; and (ii) equally split all net sublicensing revenues earned under sublicense agreements that the Company enters into with any third party before commencement of the first Phase I clinical trial for a licensed product. No IPR&D expense was recorded during the years ended December 31, 2023 and 2022. As of December 31, 2023 and 2022 , no milestones are accrued as the underlying contingencies are not probable or estimable. LifeArc In April 2020, the Company entered into a license agreement with LifeArc (the LifeArc Agreement) under which the Company was granted an exclusive, worldwide license to certain materials, know-how, and intellectual property rights owned or controlled by LifeArc to develop, manufacture, use, and commercialize certain ULK inhibitors for all applications. Under the LifeArc Agreement, the Company was granted the license at no upfront cost and a period of three months after the effective date to conduct experiments on LifeArc’s compounds. Upon completion of this initial testing period, the Company had the option to continue the license and make a one-time license payment of $ 75,000 to LifeArc, which payment was subsequently made in 2020. The Company is obligated to make future development milestone payments for a licensed product of up to $ 11.0 million and sales milestone payments of up to $ 50.0 million. The Company is also obligated to pay royalties on net sales of all licensed products, in the low-single digit percentages, subject to certain reductions. No IPR&D expense was recorded during the years ended December 31, 2023 and 2022. As of December 31, 2023 and 2022 , no milestones are accrued as the underlying contingencies are not probable or estimable. University of California, San Francisco In December 2018, the Company entered into a license agreement, as amended (the UCSF Agreement), with The Regents of the University of California, San Francisco (the Regents), under which the Company was granted an exclusive, worldwide, royalty-bearing license under certain patent rights claiming novel covalent inhibitors of GTP- and GDP-bound RAS for the development and commercialization of products covered by such patent rights for the prevention, treatment and amelioration of human cancers and other diseases and conditions. The UCSF Agreement was amended in May 2021. Under the UCSF Agreement, the Company made upfront payments of $ 50,000 to the Regents and paid the Regents an annual license maintenance fee during the term of the license, but such fee would not have been due on any anniversary if, on that date, the Company was then making royalty payments to the Regents. The Company was obligated to make future development and regulatory milestone payments of up to $ 6.4 million and a sales milestone payment of $ 2.0 million for either of the first two licensed products. The Company was also obligated to pay royalties on net sales of all licensed products in the low-single digit percentages, subject to a minimum annual royalty payment in the low six figures, commencing on the year of the first sale of a licensed product and continuing, on a licensed product-by-licensed product and country-by-country basis, until there were no valid claims of the licensed patent rights covering the licensed product in such country. Additionally, the Company was obligated to pay tiered sublicensing fees, with the first two tiers in the low-to-mid teen percentages and the third tier at 30 %, on certain fees the Company received from any sublicense that the Company granted, depending on the stage of development of a licensed product when such sublicense was granted. Prior to the execution of the amendment, the Company was obligated to make a cash payment to the Regents in the event of the Company’s initial public offering, a change of control transaction or a reverse merger (the Corporate Milestone). In the amendment, the amount of the cash payment payable upon the Company’s achievement of a Corporate Milestone was reduced and the Company agreed to issue the Regents 944,945 shares of the Company’s common stock, which issuance was not contingent upon the achievement of a Corporate Milestone and occurred in May 2021. In August 2021, following the achievement of the Corporate Milestone, the Company made a cash payment to the Regents in the amount of $ 1.7 million. No IPR&D expense was recorded during the years ended December 31, 2023 and 2022. As of December 31, 2023 and 2022 , no milestones are accrued as the underlying contingencies are not probable or estimable. On August 7, 2023, the Company sent a notice of termination to the Regents with respect to the UCSF Agreement. The termination of the UCSF Agreement, including termination of the exclusive license granted to the Company under the UCSF Agreement, was effective as of October 6, 2023.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Stockholders' Equity	Note 9. Stockholders’ equity Common stock Holders of the Company's common stock are entitled to one vote for each share held on the applicable record date with respect to all matters submitted to a vote of stockholders, including the election of directors, and do not have cumulative voting rights. Common stockholders are entitled to receive dividends, as may be declared by the Company’s board of directors. As of December 31, 2023 , no dividends had been declared. In August 2022, the Company entered into an Open Market Sale Agreement (the Sale Agreement) with Jefferies LLC (the Agent), pursuant to which the Company may offer and sell shares of the Company’s common stock having an aggregate offering price of up to $ 200 million from time to time, in “at the market” offerings through the Agent. Sales of the shares of common stock, if any, will be made at prevailing market prices at the time of sale, or as otherwise agreed with the Agent. The Agent will receive a commission from the Company of up to 3.0 % of the gross proceeds of any shares of common stock sold under the Sale Agreement. There have been no shares of the Company's common stock sold under the Sale Agreement as of December 31, 2023. In December 2022, the Company completed the 2022 Offering in which the Company issued and sold 15,384,616 shares of its common stock at a price to the public of $ 6.50 per share. Proceeds from the offering were $ 94.9 million, net of underwriting discounts and commissions and offering costs of $ 5.1 million. Shares of common stock subject to repurchase During 2018, the Company issued 1,458,332 shares of restricted stock for cash at a price of $ 0.0001 per share. The restricted stock vests 25 % one year from the vesting commencement date and monthly thereafter over a three-year period and is subject to repurchase by the Company in the event of any voluntary or involuntary termination of services to the Company prior to vesting. Any shares subject to repurchase by the Company are not deemed, for accounting purposes, to be outstanding until those shares vest. As of December 31, 2023 and 2022 , no shares of common stock were subject to repurchase by the Company. The unvested stock liability related to these awards is immaterial for all periods presented. For the years ended December 31, 2023 and 2022 , zero and 212,674 shares vested, respectively.

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	Note 10. Stock-based compensation In July 2021, the Company’s board of directors adopted and the Company’s stockholders approved the Company’s 2021 Incentive Award Plan (the 2021 Plan), which became effective in connection with the IPO. Upon the adoption of the 2021 Plan, the Company ceased making equity grants under its 2018 Equity Incentive Plan (the 2018 Plan). Under the 2021 Plan, the Company may grant stock options, restricted stock, restricted stock units, stock appreciation rights, and other stock or cash-based awards to individuals who are then employees, officers, directors or non-entity consultants of the Company. A total of 15,150,000 shares of common stock were initially reserved for issuance under the 2021 Plan. In addition, the number of shares of common stock available for issuance under the 2021 Plan may be increased annually on the first day of each calendar year during the term of the 2021 Plan, beginning in 2022, by an amount equal to the lesser of (i) 5 % of the shares of common stock outstanding on the final day of the immediately preceding calendar year or (ii) such smaller number of shares as determined by the Company’s board of directors or an authorized committee of the board of directors. As of December 31, 2023, there were 15,342,797 stock-based awards available for future grant under the 2021 Plan. Subsequent to July 2021, no further awards will be granted under the 2018 Plan and all future stock-based awards will be granted under the 2021 Plan. To the extent outstanding options or restricted stock granted under the 2018 Plan are cancelled, forfeited, repurchased, or otherwise terminated without being exercised or becoming vested, and would otherwise have been returned to the share reserve under the 2018 Plan, the number of shares underlying such awards will be available for future grant under the 2021 Plan. Options granted are exercisable at various dates as determined upon grant and will expire no more than ten years from their date of grant. Stock options generally vest over a four-year term. The exercise price of each option shall be determined by the Company’s board of directors based on the estimated fair value of the Company’s stock on the date of the option grant. The exercise price shall not be less than 100 % of the fair market value of the Company’s common stock at the time the option is granted. For holders of more than 10% of the Company’s total combined voting power of all classes of stock, incentive stock options may not be granted at less than 110 % of the fair market value of the Company’s common stock on the date of grant and for a term that exceeds five years . Early exercise was permitted for certain grants under the 2018 Plan. Stock options A summary of the Company’s stock option activity under the 2021 Plan and 2018 Plan is as follows (in thousands, except share and per share data and years): Weighted- Weighted- average remaining Aggregate average contractual intrinsic Shares exercise price term (years) value Outstanding at December 31, 2022 17,393,396 $ 5.84 8.20 $ 18,295 Granted 12,038,837 3.67 Exercised ( 624,807 ) 0.81 Canceled ( 3,836,469 ) 5.44 Outstanding at December 31, 2023 24,970,957 $ 4.98 8.12 $ 4,412 Options exercisable at December 31, 2023 11,270,914 $ 4.83 7.40 $ 4,017 The weighted-average grant date fair value of options granted for the years ended December 31, 2023 and 2022 was $ 2.70 and $ 7.43 , respectively. As of December 31, 2023, the unrecognized compensation cost related to unvested stock option grants was $ 50.4 million and is expected to be recognized as expense over approximately 2.43 years. The intrinsic value of the options exercised for the years ended December 31, 2023 and 2022 was $ 1.2 million and $ 7.8 million, respectively. Prior to the Company's IPO, certain individuals were granted the ability to early exercise their stock options. The shares of common stock issued from the early exercise of unvested stock options are restricted and continue to vest in accordance with the original vesting schedule. The Company has the option to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination. The shares purchased by the employees and non-employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be outstanding until those shares vest. The cash received in exchange for exercised and unvested shares related to stock options granted is recorded as a liability for the early exercise of stock options on the accompanying consolidated balance sheets and will be transferred into common stock and additional paid-in capital as the shares vest. As of December 31, 2023 and 2022, there were 371,876 s hares and 1,115,105 shares subject to repurchase by the Company, respectively. As of December 31, 2023 and 2022, the Company recorded $ 464,000 and $ 1.7 million o f liabilities associated with shares issued with repurchase rights, respectively, which is recorded in accrued expenses and other current liabilities. The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants were as follows: Year Ended December 31, 2023 2022 Risk-free interest rate 3.46 %- 4.73 % 1.46 %- 4.23 % Expected volatility 82.01 %- 85.81 % 83.91 %- 87.11 % Expected term (in years) 5.50 - 6.08 5.50 - 6.08 Expected dividend yield - -% - -% Employee stock purchase plan In July 2021, the Company’s board of directors adopted and the Company’s stockholders approved the ESPP, which became effective in connection with the IPO. The ESPP permits participants to contribute up to a specified percentage of their eligible compensation during a series of offering periods of 24 months , each comprised of four six-month purchase periods, to purchase the Company’s common stock. The purchase price of the shares will be 85 % of the fair market value of the Company’s common stock on the first day of trading of the applicable offering period or on the applicable purchase date, whichever is lower. A total of 1,260,000 shares of common stock was initially reserved for issuance under the ESPP. In addition, the number of shares of common stock available for issuance under the ESPP may be increased annually on the first day of each calendar year during the term of the ESPP , beginning in 2022, by an amount equal to the lesser of (i) 1% of the shares of common stock outstanding on the final day of the immediately preceding calendar year or (ii) such smaller number of shares as determined by the Company’s board of directors or an authorized committee of the board of directors. The Company recognized stock-based compensation expense related to the ESPP of $ 1.5 million and $ 1.1 million during the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, the unrecognized compensation cost related to the ESPP was $ 1.9 million and is expected to be recognized as expense over approximately 1.94 years. As of December 31, 2023 and 2022, $ 46,000 and $ 74,000 has been withheld on behalf of employees for future purchase under the ESPP, respectively, and is included in accrued expenses and other current liabilities on the consolidated balance sheets. The Company issued and sold 388,933 and 202,882 shares under the ESPP during the years ended December 31, 2023 and 2022, respectively. The assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock to be purchased under the ESPP were as follows: Year Ended December 31, 2023 2022 Risk-free interest rate 4.43 %- 5.36 % 2.24 %- 4.68 % Expected volatility 70.00 %- 82.79 % 73.05 %- 87.89 % Expected term (in years) 0.49 - 1.99 0.50 - 1.99 Expected dividend yield - -% - -% Stock-based compensation expense The allocation of stock-based compensation for all stock awards was as follows (in thousands): Year Ended December 31, 2023 2022 Research and development $ 13,972 $ 11,620 General and administrative 12,259 8,489 Total $ 26,231 $ 20,109 Common stock reserved for future issuance Common stock reserved for future issuance consisted of the following as of December 31, 2023 and 2022: December 31, December 31, 2023 2022 Stock options issued and outstanding 24,970,957 17,393,396 Awards available for future grant 15,342,797 16,022,747 Shares available for purchase under the ESPP 2,080,681 965,131 Total 42,394,435 34,381,274

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases	Note 11. Leases Operating leases The Company has facility leases for office space under non-cancellable and cancelable operating leases with various expiration dates through 2032 and equipment under a non-cancellable operating lease with a term expiring in 2026 . Total lease costs were approximately $ 11.4 million and $ 7.7 million, including operating lease costs of $ 7.7 million and $ 5.8 million, variable lease costs of $ 3.7 million and $ 1.8 million, and short-term lease costs of $ 0 and $ 86,000 during the years ended December 31, 2023 and 2022, respectively. The Company paid $ 6.9 million and $ 1.2 million in ca sh for operating leases that were included in the operating activities section of the consolidated statements of cash flows for the years ended December 31, 2023 and 2022, respectively. The weighted-average remaining lease term and the weighted-average discount rate of the Company’s operating leases were 8.29 years and 8.95 % a t December 31, 2023 , respectively. The weighted-average remaining lease term and the weighted-average discount rate of the Company’s operating leases were 9 .26 years and 8.96 % at December 31, 2022, respectively. The weighted-average remaining lease term does not include any renewal options at the election of the Company. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. Facility leases In September 2020, the Company entered into a lease agreement for 59,407 square feet of laboratory and office space in San Diego, California, which represented a portion of a new facility that was under construction and which was subsequently amended in March 2021 to expand the rented premises by 18,421 square feet (the 2020 Lease). The construction and design of the asset was the primary responsibility of the lessor. The Company was involved in certain aspects of construction and design for certain interior features and leasehold improvements that is beneficial to the Company to better suit its business needs and intended purpose of the space. The lease is accounted for as an operating lease and commenced in August 2021 . In April 2022, the 2020 Lease was modified to amend the rent commencement date from February 2022 to May 2022 . The 2020 Lease, as amended, has a term of 10.75 years and includes aggregate monthly payments to the lessor of approximately $ 51.6 million beginning in May 2023 with a rent escalation clause, and a tenant improvement allowance of approximately $ 16.8 million. The Company is responsible for its share of operating expenses based on actual operating expenses incurred by the landlord. The 2020 Lease is cancellable at the Company’s request after the 84 th month with 12 months written notice and a lump-sum cancellation payment of $ 2.5 million. The termination option has not been included in the Company's operating lease assets and liabilities. As discussed in Note 2, the Company provided a letter of credit to the lessor for $ 408,000 , which expires July 29, 2032 . In December 2021, the Company entered into a lease agreement for 29,542 square feet of office and laboratory space in South San Francisco, California. The lease is accounted for as an operating lease with the associated operating lease assets and liabilities recorded upon commencement, which occurred in July 2022 . The non-cancellable operating lease has an initial term of 124 months with an option to extend the lease term by 5 years at the then-current market rates and includes aggregate monthly payments to the lessor of approximately $ 34.4 million beginning in November 2022 with a rent escalation clause and a tenant improvement allowance of approximately $ 8.2 million. The renewal option has not been included in the Company's operating lease assets and liabilities. The Company is responsible for its share of operating expenses based on actual operating expenses incurred by the landlord. The construction and design of the tenant improvements was the primary responsibility of the lessor. While the Company was involved in certain aspects of construction and design for certain interior features and leasehold improvements that is beneficial to the Company to better suit its business needs and intended purpose of the space, all construction was handled directly by the landlord. The Company was not deemed to be the accounting owner of the tenant improvements prior to or after the construction period. All payments made by the Company for landlord-owned tenant improvements were recorded as prepaid rent on the consolidated balance sheets prior to lease commencement and included in the operating lease asset upon lease commencement. In February 2022, the expected project costs exceeded the tenant improvement allowances by $ 5.1 million, which was paid directly to the landlord by the Company and was recorded as prepaid rent in the consolidated balance sheets and as a cash outflow from operating activities in the consolidated statements of cash flows. Upon lease commencement, the $ 5.1 million of prepaid rent was included in the operating lease asset . The Company paid a security deposit of $ 874,000 in December 2021 that was recorded as other assets in the consolidated balance sheets. Future minimum lease payments under the operating leases with initial lease terms in excess of one year as of December 31, 2023 are as follows (in thousands): Year ending December 31, 2024 $ 8,752 2025 9,024 2026 9,170 2027 9,199 2028 9,277 Thereafter 35,098 Total lease payments $ 80,520 Less: Amount representing interest ( 24,661 ) Operating lease liabilities $ 55,859

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 12. Commitments and contingencies Liabilities for loss contingencies arising from claims, assessments, litigation, fines, penalties and other sources are recorded when it is probable that a liability has been incurred and the amount can be reasonably estimated. There are no matters currently outstanding for which any such liabilities have been accrued.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Note 13. Income taxes No provision for federal, state or foreign income taxes has been recorded for the years ended December 31, 2023 and 2022. The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities as of December 31, 2023 and 2022 were as follows (in thousands): December 31, December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 59,326 $ 52,470 Intangible assets 25,274 36,195 Capitalized research and development costs 35,711 21,004 Operating lease liabilities 11,767 15,451 Research and development credits 14,956 9,853 Contribution of common stock 3,262 4,907 Stock-based compensation 4,007 3,961 Other, net 2,016 3,455 Total deferred tax assets 156,319 147,296 Deferred tax liabilities: Property and equipment ( 4,511 ) ( 5,809 ) Operating lease assets ( 7,975 ) ( 11,334 ) Total deferred tax liabilities ( 12,486 ) ( 17,143 ) Valuation allowance ( 143,833 ) ( 130,153 ) Net deferred tax assets $ — $ — The Company has established a valuation allowance against net deferred tax assets due to the uncertainty that such assets will be realized. The Company periodically evaluates the recoverability of the deferred tax assets. At such time as it is determined that it is more likely than not that deferred tax assets will be realizable, the valuation allowance will be reduced. The Company has recorded a full valuation allowance of $ 143.8 million as of December 31, 2023, as it does not believe it is more likely than not that the deferred tax assets will be realized primarily due to the generation of pre-tax book losses, the lack of feasible tax-planning strategies, the limited existing taxable temporary differences, and the subjective nature of forecasting future taxable income into the future. The Company increased its valuation allowance by $ 13.7 million during the year ended December 31, 2023. A reconciliation of the federal statutory income tax rate and the Company’s effective income tax rate is as follows: Year ended December 31, 2023 2022 Federal statutory income tax rate 21.0 % 21.0 % State income taxes, net of federal benefit ( 9.8 ) 7.6 Change in valuation allowance ( 11.1 ) ( 30.3 ) Other permanent differences ( 1.6 ) ( 0.3 ) Research and development credits 5.0 2.9 State net operating loss ( 0.4 ) ( 0.1 ) Other ( 3.1 ) ( 0.8 ) Effective income tax rate — % — % At December 31, 2023 , the Company had federal, California, and other state net operating loss (NOL) carryforwards of $ 200.9 million, $ 243.1 million, and $ 2.5 million, respectively. The federal NOL carryforwards will carryforward indefinitely and can offset 80 % of future taxable income each year, the California NOL carryforwards begin to expire in 2038 , and the other state NOL carryforwards begin to expire in 2035 . At December 31, 2023 , the Company also had federal, California, and Massachusetts research tax credit carryforwards of approximately $ 12.1 million, $ 7.1 million, and $ 554,000 , respectively. The federal research tax credit carryforwards begin to expire in 2038 , the California research tax credit carryforward does not expire and can be carried forward indefinitely until utilized, and the Massachusetts research tax credit carryforwards begin to expire in 2036 . At December 31, 2023 , the Company also had federal orphan drug credit carryforwards of approximately $ 535,000 . The federal orphan drug credit carryforwards begin to expire in 2043 . At December 31, 2023 , the Company also had federal and California charitable contribution carryforwards of $ 15.5 million. The charitable contribution carryforwards begin to expire in 2024 . The above NOL carryforward and the research tax credit carryforwards are subject to an annual limitation under Section 382 and 383 of the Internal Revenue Code of 1986, as amended (IRC), and similar state provisions due to ownership change limitations that have occurred which will limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382 and 383, results from transactions increasing ownership of certain stockholders or public groups in the stock of the corporation by more than 50 percentage points over a three-year period. The Company has not completed an IRC Section 382/383 analysis regarding the limitation of net operating loss and research and development credit carryforwards. If a change in ownership were to have occurred, additional NOL and tax credit carryforwards could be eliminated or restricted. If eliminated, the related asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance. Due to the existence of the valuation allowance, limitations created by future ownership changes, if any, related to the Company’s operations in the United States will not impact the Company’s effective tax rate. The Company recognizes a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more likely than not recognition at the effective date to be recognized. A reconciliation of the beginning and ending amount of unrecognized tax benefits for 2023 and 2022, excluding interest and penalties, is as follows (in thousands): Year ended December 31, 2023 2022 Balance at the beginning of the year $ 2,725 $ 1,182 Increase related to prior year positions 99 — Increase related to current year positions 1,272 1,543 Balance at the end of the year $ 4,096 $ 2,725 Included in the balance of unrecognized tax benefits as of December 31, 2023 is $ 3.8 million that, if recognized, would reduce the Company’s annual effective tax rate, subject to valuation allowance. The Company does not anticipate any significant changes to unrecognized tax benefits over the next 12 months. The Company has filed income tax returns in Australia, the United States, California, and various other state jurisdictions. The Company is not currently under examination in any of these jurisdictions, and all of the Company’s tax years remain effectively open in all jurisdictions to examination due to net operating loss carryforwards. The Company’s policy is to recognize interest expense and penalties related to income tax matters as tax expense. For the years ended December 31, 2023 and 2022 , the Company has no t recognized any interest or penalties related to income taxes.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Net Loss Per Share	Note 14. Net loss per share The following table summarizes the computation of basic and diluted net loss per share of the Company (in thousands, except share and per share data): Year Ended December 31, 2023 2022 Net loss $ ( 125,042 ) $ ( 242,805 ) Weighted-average shares of common stock used in computing net loss per share, basic and diluted 150,184,994 122,024,848 Net loss per share, basic and diluted $ ( 0.83 ) $ ( 1.99 ) The Company’s potentially dilutive securities, which include options to purchase common stock, shares purchasable under the ESPP and common stock subject to repurchase related to options early exercised, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share is the same. The Company excluded the following potential common shares, presented as amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: December 31, December 31, 2023 2022 Options to purchase common stock 24,970,957 17,393,396 Options early exercised subject to future vesting 371,876 1,115,105 Estimated shares purchasable under the ESPP 1,301,205 803,767 Total potentially dilutive shares 26,644,038 19,312,268

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Retirement Plan	Note 15. Retirement plan The Company sponsors an employee savings plan that qualifies as a deferred salary arrangement under Section 401(k) of the US Internal Revenue Code. Participating employees may defer up to the Internal Revenue Service annual contribution limit. The Company provides a safe harbor contribution of 3.0 % of the employee’s compensation, not to exceed eligible limits. For the years ended December 31, 2023 and 2022, the Company incurre d $ 958,000 and $ 858,000 in expenses related to the safe harbor contribution, respectively.

CARES Act

CARES Act	12 Months Ended
	Dec. 31, 2023
Risks and Uncertainties [Abstract]
CARES Act	Note 16. CARES Act On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was enacted in response to the COVID-19 pandemic. The CARES Act provided for a refundable employee retention credit, which can be used to offset payroll tax liabilities. On March 11, 2021, President Biden signed the American Rescue Plan Act, which includes several provisions previously enacted under the CARES Act, such as measures that extended and expanded the employee retention credit through December 31, 2021. However, on November 15, 2021, President Biden signed into law the Infrastructure Investment and Jobs Act, which terminated the employee retention credit for wages paid in the fourth calendar quarter of 2021 for employers that are not recovery startup businesses. Pursuant to the employee retention credit, eligible employers could receive a 50 % or 70 % credit on qualified wages against their employment taxes each quarter during the eligible periods in 2020 and 2021, respectively, with any excess credits eligible for refunds. During the year ended December 31, 2022, the Company recorded an employee retention credit of $ 2.2 million upon completion of an analysis providing reasonable assurance that the Company met the conditions set forth in the CARES Act and it was reasonably assured that the Company would receive the employee retention credit. The employee retention credit is recorded in research and development expenses and general and administrative expenses in the manner in which the qualified wages and related costs were classified.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Note 17. Related party transactions Affini-T Therapeutics, Inc. The Company holds a $ 2.0 million equity investment in Affini-T. One of the Company’s board members is also a member of the board of Affini-T. Erasca Foundation In May 2021, the Company established the Erasca Foundation to provide support such as funding research, patient advocacy, patient support and education in underserved populations, and funding for other initiatives to positively impact society that align with the Company’s mission. The Company's chief executive officer and certain board members serve as directors of the Erasca Foundation and the Company's chief executive officer, chief financial officer and chief business officer, and general counsel are also officers of the Erasca Foundation. In April 2023, the Company loaned the Erasca Foundation $ 125,000 in exchange for a non-interest bearing promissory note that matures one year following the date of the note. In December 2023, the Erasca Foundation repaid the note. As of December 31, 2023 and 2022 , no amounts were recorded related to the non-interest bearing promissory note in the consolidated balance sheets.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Note 18. Subsequent events 10,000 square feet of office space with a sublease term of three years which includes an option for the subtenant to renew for an additional year and an early termination clause. In January and February 2024, the Company granted options to purchase an aggregate of 9,827,650 shares of its common stock to employees and board members at a weighted-average exercise price of $ 1.71 per share.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Use of Estimates	Use of estimates The preparation of the Company’s consolidated financial statements in conformity with US GAAP requires the Company to make estimates and assumptions that impact the reported amounts of assets, liabilities, expenses, and the disclosure of contingent assets and liabilities in the consolidated financial statements and accompanying notes. Accounting estimates and management judgments reflected in the consolidated financial statements include, but are not limited to, the accrual of research and development expenses, stock-based compensation expense, and the incremental borrowing rate for determining the operating lease asset and liability. Management evaluates its estimates on an ongoing basis. Although estimates are based on the Company’s historical experience, knowledge of current events, and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Concentration of Credit Risk and Off-Balance Sheet Risk	Concentration of credit risk and off-balance sheet risk Financial instruments which potentially subject the Company to significant concentration of credit risk consist of cash and cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts, and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company’s investment policy includes guidelines for the quality of the related institutions and financial instruments and defines allowable investments that the Company may invest in, which the Company believes minimizes the exposure to concentration of credit risk.
Cash, Cash Equivalents, and Restricted Cash	Cash, cash equivalents and restricted cash Cash and cash equivalents include cash in readily available checking and savings accounts, and money market funds. The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents. The Company had deposited cash of $ 408,000 as of December 31, 2023 and 2022 to secure a letter of credit in connection with the lease of the Company’s facilities (see Note 11). The Company has classified the restricted cash as a noncurrent asset on its consolidated balance sheets. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same amounts shown in the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 93,075 $ 284,217 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 93,483 $ 284,625
Marketable securities and investments	Marketable securities and investments The Company classifies all marketable securities as available-for-sale, as the sale of such securities may be required prior to maturity. Management determines the appropriate classification of its marketable securities at the time of purchase. Marketable securities with original maturities beyond three months at the date of purchase and which mature at, or less than 12 months from, the balance sheet date are classified as short-term marketable securities. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized. The amortized cost of available-for-sale debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. The Company regularly reviews all of its marketable securities for declines in fair value. The review includes the consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity of the unrealized loss(es), whether the Company has the intent to sell the securities and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. If the decline in fair value is due to credit-related factors, a loss is recognized in net income; whereas, if the decline in fair value is not due to credit-related factors, the loss is recorded in other comprehensive income (loss). Realized gains and losses on available-for-sale securities are included in other income or expense. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. Through its wholly-owned subsidiary, Erasca Ventures, the Company has also invested in equity securities of a company whose securities are not publicly traded and whose fair value is not readily available (see Notes 3 and 17). This investment is recorded using cost minus impairment, plus or minus changes in its estimated fair value resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Investments in equity securities without readily determinable fair values are assessed for potential impairment on a quarterly basis based on qualitative factors. This investment is included in other assets in the Company's consolidated balance sheets.
Fair Value Measurements	Fair value measurements Certain assets and liabilities are carried at fair value under US GAAP. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Financial assets and liabilities carried at fair value are classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: Level 1—Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2—Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability. Level 3—Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).
Property and Equipment, Net	Property and equipment, net Property and equipment are stated at cost less accumulated depreciation. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years . Leasehold improvements are amortized over the shorter of the estimated useful lives of the assets or the remaining lease term.
Impairment of Long-Lived Assets	Impairment of long-lived assets The Company continually evaluates long-lived assets for potential impairment when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparing the book values of the assets to the expected future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book values of the assets exceed their fair value. The Company did no t recognize any impairment losses for the years ended December 31, 2023 and 2022 .
Leases	Leases The Company leases real estate facilities and equipment under non-cancelable and cancelable operating leases with various expiration dates through fiscal year 2032. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. Operating leases are included in operating lease assets and in operating lease liabilities in the accompanying consolidated balance sheets. Operating lease assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term discounted based on the more readily determinable of (i) the rate implicit in the lease or (ii) the Company’s incremental borrowing rate (which is the estimated rate the Company would be required to pay for a collateralized borrowing equal to the total lease payments over the term of the lease). Because the Company’s operating leases generally do not provide an implicit rate, the Company estimates its incremental borrowing rate based on the information available at lease commencement date for borrowings with a similar term. The Company’s operating lease assets are measured based on the corresponding operating lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs incurred and (iii) tenant incentives under the lease. The Company does not assume renewals or early terminations unless it is reasonably certain to exercise these options at commencement. The Company elected the practical expedient which allows the Company to not allocate consideration between lease and non-lease components. Variable lease payments are recognized in the period in which the obligations for those payments are incurred. In addition, the Company elected the practical expedient such that it does not recognize lease assets or lease liabilities for leases with a term of 12 months or less for all asset classes. Operating lease expense is recognized on a straight-line basis over the lease term. Certain of the Company's real estate leases include tenant improvement allowances, which are recognized as lease incentives and amortized on a straight-line basis over the lease term as an offset to rent expense.
Research and Development Expense	Research and development expense Research and development expenses consist of external and internal costs associated with the Company’s research and development activities, including its discovery and research efforts and the preclinical and clinical development of its product candidates. Research and development costs are expensed as incurred. The Company’s research and development expenses include external costs, consisting of expenses incurred under arrangements with third parties, such as contract research organizations (CROs), contract manufacturing organizations (CMOs), consultants and its scientific advisors; and internal costs, consisting of employee-related expenses, including salaries, benefits, and stock-based compensation for those individuals involved in research and development efforts, the costs of laboratory supplies and acquiring, developing and manufacturing preclinical study materials, and facilities and depreciation, which include direct and allocated expenses for rent of facilities and depreciation. The Company records accruals for estimated research and development costs, comprising payments for work performed by third party contractors, laboratories, and others. Some of these contractors bill monthly based on actual services performed, while others bill periodically based upon achieving certain contractual milestones. For the latter, the Company accrues the expenses as goods or services are used or rendered. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized as prepaid expenses until the related goods are delivered or services are performed.
In-Process Research and Development Expense	In-process research and development expense The Company has acquired rights as part of asset acquisitions or in-licenses to develop and commercialize product candidates. Upfront payments that relate to the acquisition of a new product candidate, as well as pre-commercial milestone payments, are immediately expensed as in-process research and development (IPR&D) in the period in which they are incurred, provided that the new product candidate did not also include processes or activities that would constitute a “business” as defined under US GAAP, the product candidate has not achieved regulatory approval for marketing and, absent obtaining such approval, has no established alternative future use. The Company accounts for contingent consideration payable upon achievement of certain regulatory, development or sales milestones in such asset acquisitions when the underlying contingency is probable and estimable. Milestone payments made to third parties subsequent to regulatory approval will be capitalized as intangible assets and amortized over the estimated remaining useful life of the related product.
Patent Costs	Patent costs The Company expenses all costs as incurred in connection with patent applications (including direct application fees, and the legal and consulting expenses related to making such applications) and such costs are included in general and administrative expenses in the consolidated statements of operations and comprehensive loss.
Share-based Compensation	Stock-based compensation The Company measures employee and nonemployee stock-based awards based on the fair value on the date of grant and records compensation expense on a straight-line basis over the requisite service period of the award. All stock-based compensation costs are recorded in the consolidated statements of operations and comprehensive loss based upon the underlying employees' or nonemployees' roles within the Company. Forfeitures are accounted for as they occur. The fair value of stock option grants and shares purchasable under the Company's 2021 Employee Stock Purchase Plan (ESPP) is estimated on the date of grant using the Black-Scholes options-pricing model, which requires inputs based on certain subjective assumptions, including the: • Risk-free interest rate. The risk-free interest rate is based on the US Treasury zero-coupon issues in effect at the time of grant for periods corresponding with the expected term of the stock-based awards. • Expected volatility. Given that the Company’s common stock was privately held prior to the IPO, there was no active trading market for its common stock. The Company derived the expected volatility from the average historical volatilities over a period approximately equal to the expected term of comparable publicly traded companies within its peer group that were deemed to be representative of future stock price trends. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. • Expected term. The expected term represents the period that the stock-based awards are expected to be outstanding. The expected term of stock options issued is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term) as the Company has concluded that its stock option exercise history does not provide a reasonable basis upon which to estimate expected term. • Expected dividend yield. The Company has never paid dividends on its common stock and does not anticipate paying any dividends in the foreseeable future. Therefore, the Company used an expected dividend yield of zero . The fair value of each restricted common stock award is estimated on the date of grant based on the fair value of the Company’s common stock on that same date.
Income Taxes	Income taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s consolidated financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. As of December 31, 2023 , the Company’s tax years since inception are subject to examination by taxing authorities due to the Company’s unutilized net operating losses and tax credits.
Comprehensive Income (Loss)	Comprehensive income (loss) The Company reports all components of comprehensive income (loss), including net loss, in the consolidated financial statements in the period in which they are recognized. Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities. Other comprehensive income (loss) includes unrealized gains and losses on marketable securities, which was the only difference between net loss and comprehensive loss for the applicable periods.
Net Loss Per Share	Net loss per share The Company’s net loss is equivalent to net loss attributable to common stockholders for all periods presented. Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, options to purchase common stock, shares purchasable under the ESPP and common stock subject to repurchase related to options early exercised are considered to be potentially dilutive securities. Basic and diluted net loss per share is presented in conformity with the two-class method required for participating securities as the shares issued upon the early exercise of stock options subject to repurchase are considered to be participating securities because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. The Company’s participating securities do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. As the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.
Segments	Segments The Company has determined that its chief executive officer is the chief operating decision maker (CODM). The Company operates and manages the business as one reporting and one operating segment, which is the business of discovering and developing precision medicines for the benefit of patients with cancer. The Company’s CODM reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s assets are located in the United States.
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements Not Yet Adopted	Recently adopted accounting pronouncements There were no accounting pronouncements adopted by the Company during the year ended December 31, 2023. Recently issued accounting pronouncements not yet adopted From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act) and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company can adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which is intended to provide enhancements to segment disclosures, even for entities with only one reportable segment. In particular, the standard will require disclosures of significant segment expenses regularly provided to the chief operating decision maker and included within each reported measure of segment profit and loss. The standard will also require disclosure of all other segment items by reportable segment and a description of its composition. Finally, the standard will require disclosure of the title and position of the chief operating decision maker and an explanation of how the chief operating decision maker uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. The standard is effective for annual periods beginning after December 15, 2023, and interim periods within annual periods beginning after December 15, 2024. Early adoption is permitted. Retrospective application to all prior periods presented in the financial statements is required. The Company is currently evaluating the impact of the standard on the presentation of its consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which is intended to provide enhancements to annual income tax disclosures. In particular, the standard will require more detailed information in the income tax rate reconciliation, as well as the disclosure of income taxes paid disaggregated by jurisdiction, among other enhancements. The standard is effective for the Company in its annual period beginning after December 15, 2025 and early adoption is permitted. The standard allows for adoption on a prospective basis, with a retrospective option. The Company is currently evaluating the impact of the standard on the presentation of its consolidated financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same amounts shown in the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 93,075 $ 284,217 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 93,483 $ 284,625

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Summary of Financial Assets Measured at Fair Value on Recurring Basis	The following tables summarize the Company’s financial assets measured at fair value on a recurring basis and their respective input levels based on the fair value hierarchy (in thousands): Fair value measurements as of December 31, 2023 using Quoted prices in Significant Significant active markets other unobservable December 31, for identical observable inputs 2023 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 83,101 $ 83,101 $ — $ — US treasury securities (2) 93,303 93,303 — — US government agency securities (2) 26,824 — 26,824 — Corporate debt securities (2) 10,734 — 10,734 — Commercial paper (2) 88,414 — 88,414 — US treasury securities (3) 9,642 9,642 — — Total fair value of assets $ 312,018 $ 186,046 $ 125,972 $ — (1) Included as cash and cash equivalents on the consolidated balance sheets. (2) Included as short-term marketable securities on the consolidated balance sheets. (3) Included as long-term marketable securities on the consolidated balance sheets. Fair value measurements as of December 31, 2022 using Quoted prices in Significant Significant active markets other unobservable December 31, for identical observable inputs 2022 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 255,080 $ 255,080 $ — $ — US treasury securities (2) 127,476 127,476 — — US government agency securities (2) 1,468 — 1,468 — Corporate debt securities (2) 3,301 — 3,301 — Commercial paper (2) 18,519 — 18,519 — Supranational debt securities (2) 639 — 639 — Total fair value of assets $ 406,483 $ 382,556 $ 23,927 $ — (1) Included as cash and cash equivalents on the consolidated balance sheets. (2) Included as short-term marketable securities on the consolidated balance sheets.

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Summary of Marketable Securities Accounted for Available-for-Sale Securities	The following tables summarize the Company’s marketable securities accounted for as available-for-sale securities (in thousands, except years): December 31, 2023 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 93,377 $ 74 $ ( 148 ) $ 93,303 US government agency securities 1 or less 26,783 45 ( 4 ) 26,824 Corporate debt securities 1 or less 10,719 15 — 10,734 Commercial paper 1 or less 88,356 68 ( 10 ) 88,414 US treasury securities 1 - 2 9,605 37 — 9,642 Total $ 228,840 $ 239 $ ( 162 ) $ 228,917 December 31, 2022 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 128,504 $ 5 $ ( 1,033 ) $ 127,476 US government agency securities 1 or less 1,467 1 — 1,468 Corporate debt securities 1 or less 3,309 — ( 8 ) 3,301 Commercial paper 1 or less 18,519 — — 18,519 Supranational debt securities 1 or less 645 — ( 6 ) 639 Total $ 152,444 $ 6 $ ( 1,047 ) $ 151,403
Summary of Fair Values and Gross Unrealized Losses for Available-for-sale Securities	The following tables present fair values and gross unrealized losses for those available-for-sale securities that were in an unrealized loss position as of December 31, 2023 and 2022, aggregated by category and the length of time that the securities have been in a continuous loss position (in thousands): December 31, 2023 Unrealized losses less than 12 months Unrealized losses 12 months or greater Total Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses US treasury securities $ 74,912 $ ( 148 ) $ — $ — $ 74,912 $ ( 148 ) US government agency securities 6,950 ( 4 ) — — 6,950 ( 4 ) Corporate debt securities 748 — — — 748 — Commercial paper 22,944 ( 10 ) — — 22,944 ( 10 ) Total $ 105,554 $ ( 162 ) $ — $ — $ 105,554 $ ( 162 ) December 31, 2022 Unrealized losses less than 12 months Unrealized losses 12 months or greater Total Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses US treasury securities $ 60,652 $ ( 129 ) $ 44,048 $ ( 904 ) $ 104,700 $ ( 1,033 ) Corporate debt securities 2,560 ( 8 ) — — 2,560 ( 8 ) Supranational debt securities 639 ( 6 ) — — 639 ( 6 ) Total $ 63,851 $ ( 143 ) $ 44,048 $ ( 904 ) $ 107,899 $ ( 1,047 )

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): December 31, December 31, 2023 2022 Laboratory equipment $ 5,620 $ 4,815 Furniture and fixtures 4,099 4,104 Leasehold improvements 18,173 17,837 Computer equipment and software 1,667 1,559 Property and equipment 29,559 28,315 Less accumulated depreciation and amortization ( 7,232 ) ( 3,500 ) Property and equipment, net $ 22,327 $ 24,815

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, December 31, 2023 2022 Accrued research and development expenses $ 8,803 $ 11,523 Accrued compensation 10,311 9,395 Unvested early exercised stock option liability 464 1,690 Accrued professional services 435 873 Accrued property and equipment 13 638 Other accruals 160 217 Total $ 20,186 $ 24,336

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Stock Option Activity	A summary of the Company’s stock option activity under the 2021 Plan and 2018 Plan is as follows (in thousands, except share and per share data and years): Weighted- Weighted- average remaining Aggregate average contractual intrinsic Shares exercise price term (years) value Outstanding at December 31, 2022 17,393,396 $ 5.84 8.20 $ 18,295 Granted 12,038,837 3.67 Exercised ( 624,807 ) 0.81 Canceled ( 3,836,469 ) 5.44 Outstanding at December 31, 2023 24,970,957 $ 4.98 8.12 $ 4,412 Options exercisable at December 31, 2023 11,270,914 $ 4.83 7.40 $ 4,017
Schedule of Stock-based Compensation Expense	The allocation of stock-based compensation for all stock awards was as follows (in thousands): Year Ended December 31, 2023 2022 Research and development $ 13,972 $ 11,620 General and administrative 12,259 8,489 Total $ 26,231 $ 20,109
Summary of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consisted of the following as of December 31, 2023 and 2022: December 31, December 31, 2023 2022 Stock options issued and outstanding 24,970,957 17,393,396 Awards available for future grant 15,342,797 16,022,747 Shares available for purchase under the ESPP 2,080,681 965,131 Total 42,394,435 34,381,274
ESPP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Assumptions used to Determine Fair Value of Stock Option Grants and Stock to be Purchased under ESPP	The assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock to be purchased under the ESPP were as follows: Year Ended December 31, 2023 2022 Risk-free interest rate 4.43 %- 5.36 % 2.24 %- 4.68 % Expected volatility 70.00 %- 82.79 % 73.05 %- 87.89 % Expected term (in years) 0.49 - 1.99 0.50 - 1.99 Expected dividend yield - -% - -%
Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Assumptions used to Determine Fair Value of Stock Option Grants and Stock to be Purchased under ESPP	The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants were as follows: Year Ended December 31, 2023 2022 Risk-free interest rate 3.46 %- 4.73 % 1.46 %- 4.23 % Expected volatility 82.01 %- 85.81 % 83.91 %- 87.11 % Expected term (in years) 5.50 - 6.08 5.50 - 6.08 Expected dividend yield - -% - -%

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of Future Minimum Lease Payments under Operating Leases	Future minimum lease payments under the operating leases with initial lease terms in excess of one year as of December 31, 2023 are as follows (in thousands): Year ending December 31, 2024 $ 8,752 2025 9,024 2026 9,170 2027 9,199 2028 9,277 Thereafter 35,098 Total lease payments $ 80,520 Less: Amount representing interest ( 24,661 ) Operating lease liabilities $ 55,859

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Significant Portions of Deferred Tax Assets and Deferred Tax Liabilities	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities as of December 31, 2023 and 2022 were as follows (in thousands): December 31, December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 59,326 $ 52,470 Intangible assets 25,274 36,195 Capitalized research and development costs 35,711 21,004 Operating lease liabilities 11,767 15,451 Research and development credits 14,956 9,853 Contribution of common stock 3,262 4,907 Stock-based compensation 4,007 3,961 Other, net 2,016 3,455 Total deferred tax assets 156,319 147,296 Deferred tax liabilities: Property and equipment ( 4,511 ) ( 5,809 ) Operating lease assets ( 7,975 ) ( 11,334 ) Total deferred tax liabilities ( 12,486 ) ( 17,143 ) Valuation allowance ( 143,833 ) ( 130,153 ) Net deferred tax assets $ — $ —
Reconciliation of Federal Statutory Income Tax Rate and Effective Income Tax Rate	A reconciliation of the federal statutory income tax rate and the Company’s effective income tax rate is as follows: Year ended December 31, 2023 2022 Federal statutory income tax rate 21.0 % 21.0 % State income taxes, net of federal benefit ( 9.8 ) 7.6 Change in valuation allowance ( 11.1 ) ( 30.3 ) Other permanent differences ( 1.6 ) ( 0.3 ) Research and development credits 5.0 2.9 State net operating loss ( 0.4 ) ( 0.1 ) Other ( 3.1 ) ( 0.8 ) Effective income tax rate — % — %
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits for 2023 and 2022, excluding interest and penalties, is as follows (in thousands): Year ended December 31, 2023 2022 Balance at the beginning of the year $ 2,725 $ 1,182 Increase related to prior year positions 99 — Increase related to current year positions 1,272 1,543 Balance at the end of the year $ 4,096 $ 2,725

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Summary of Computation of Basic and Diluted Net Loss Per Share	The following table summarizes the computation of basic and diluted net loss per share of the Company (in thousands, except share and per share data): Year Ended December 31, 2023 2022 Net loss $ ( 125,042 ) $ ( 242,805 ) Weighted-average shares of common stock used in computing net loss per share, basic and diluted 150,184,994 122,024,848 Net loss per share, basic and diluted $ ( 0.83 ) $ ( 1.99 )
Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The Company’s potentially dilutive securities, which include options to purchase common stock, shares purchasable under the ESPP and common stock subject to repurchase related to options early exercised, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share is the same. The Company excluded the following potential common shares, presented as amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: December 31, December 31, 2023 2022 Options to purchase common stock 24,970,957 17,393,396 Options early exercised subject to future vesting 371,876 1,115,105 Estimated shares purchasable under the ESPP 1,301,205 803,767 Total potentially dilutive shares 26,644,038 19,312,268

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2023
Organization And Basis Of Presentation [Line Items]
Cash, cash equivalents, and short-term marketable securities			$ 312,400
Long-term marketable securities			9,642
Accumulated deficit	$ (480,971)	$ (480,971)	$ (606,013)
Net proceeds from offering		$ 95,251
2022 Registered Direct Offering | Common Stock
Organization And Basis Of Presentation [Line Items]
Stock issued and sold	15,384,616
Price per share	$ 6.5	$ 6.5
Net proceeds from offering	$ 94,900
Offering costs	$ 5,100

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) Segment	Dec. 31, 2022 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 408,000	$ 408,000
Impairment losses	0	$ 0
Expected dividend yield	$ 0
Number of operating segment | Segment	1
Number of reporting segment | Segment	1
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	7 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 93,075	$ 284,217
Restricted cash	408	408
Total cash, cash equivalents and restricted cash	$ 93,483	$ 284,625

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands		Dec. 31, 2023		Dec. 31, 2022
Assets:
Total fair value of assets		$ 312,018		$ 406,483
Money Market Funds | Cash and Cash Equivalents
Assets:
Total fair value of assets		83,101	[1]	255,080	[2]
US Treasury Securities | Short-Term Investments
Assets:
Total fair value of assets		93,303	[3]	127,476	[4]
US Treasury Securities | Long-Term Investments
Assets:
Total fair value of assets	[5]	9,642
US Government Agency Securities | Short-Term Investments
Assets:
Total fair value of assets		26,824	[3]	1,468	[4]
Corporate Debt Securities | Short-Term Investments
Assets:
Total fair value of assets		10,734	[3]	3,301	[4]
Commercial Paper | Short-Term Investments
Assets:
Total fair value of assets		88,414	[3]	18,519	[4]
Supranational Debt Securities | Short-Term Investments
Assets:
Total fair value of assets	[4]			639
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total fair value of assets		186,046		382,556
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds | Cash and Cash Equivalents
Assets:
Total fair value of assets		83,101	[1]	255,080	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | US Treasury Securities | Short-Term Investments
Assets:
Total fair value of assets		93,303	[3]	127,476	[4]
Quoted Prices in Active Markets for Identical Assets (Level 1) | US Treasury Securities | Long-Term Investments
Assets:
Total fair value of assets	[5]	9,642
Significant Other Observable Inputs (Level 2)
Assets:
Total fair value of assets		125,972		23,927
Significant Other Observable Inputs (Level 2) | US Government Agency Securities | Short-Term Investments
Assets:
Total fair value of assets		26,824	[3]	1,468	[4]
Significant Other Observable Inputs (Level 2) | Corporate Debt Securities | Short-Term Investments
Assets:
Total fair value of assets		10,734	[3]	3,301	[4]
Significant Other Observable Inputs (Level 2) | Commercial Paper | Short-Term Investments
Assets:
Total fair value of assets		$ 88,414	[3]	18,519	[4]
Significant Other Observable Inputs (Level 2) | Supranational Debt Securities | Short-Term Investments
Assets:
Total fair value of assets	[4]			$ 639
[1] Included as cash and cash equivalents on the consolidated balance sheets. Included as cash and cash equivalents on the consolidated balance sheets. Included as short-term marketable securities on the consolidated balance sheets. Included as short-term marketable securities on the consolidated balance sheets. Included as long-term marketable securities on the consolidated balance sheets.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Measurement at fair value, transfers among Level 1, Level 2 or Level 3	$ 0
Affini T Therapeutics, Inc.
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investment in equity securities	2,000,000	$ 2,000,000
Adjustments to value of investment in equity securities	$ 0

Marketable Securities - Summary

Marketable Securities - Summary of Marketable Securities Accounted for Available-for-Sale-Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 228,840	$ 152,444
Available for sale securities, Unrealized gains	239	6
Available for sale securities, Unrealized losses	(162)	(1,047)
Available for sale securities, Estimated fair value	228,917	151,403
US Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	93,377	128,504
Available for sale securities, Unrealized gains	74	5
Available for sale securities, Unrealized losses	(148)	(1,033)
Available for sale securities, Estimated fair value	$ 93,303	$ 127,476
US Treasury Securities | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year	1 year
US Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 26,783	$ 1,467
Available for sale securities, Unrealized gains	45	1
Available for sale securities, Unrealized losses	(4)
Available for sale securities, Estimated fair value	$ 26,824	$ 1,468
US Government Agency Securities | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year	1 year
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 10,719	$ 3,309
Available for sale securities, Unrealized gains	15
Available for sale securities, Unrealized losses		(8)
Available for sale securities, Estimated fair value	$ 10,734	$ 3,301
Corporate Debt Securities | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year	1 year
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 88,356	$ 18,519
Available for sale securities, Unrealized gains	68
Available for sale securities, Unrealized losses	(10)
Available for sale securities, Estimated fair value	$ 88,414	$ 18,519
Commercial Paper | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year	1 year
Supranational Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost		$ 645
Available for sale securities, Unrealized losses		(6)
Available for sale securities, Estimated fair value		$ 639
Supranational Debt Securities | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity		1 year
US Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 9,605
Available for sale securities, Unrealized gains	37
Available for sale securities, Estimated fair value	$ 9,642
US Treasury Securities | Minimum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year
US Treasury Securities | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity	2 years

Marketable Securities - Summa_2

Marketable Securities - Summary of Fair Values and Gross Unrealized Losses for Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	$ 105,554	$ 63,851
Unrealized losses less than 12 months, Unrealized losses	(162)	(143)
Unrealized losses 12 months or greater, Fair value		44,048
Unrealized losses 12 months or greater, Unrealized losses		(904)
Fair value, Total	105,554	107,899
Unrealized losses, Total	(162)	(1,047)
US Treasury Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	74,912	60,652
Unrealized losses less than 12 months, Unrealized losses	(148)	(129)
Unrealized losses 12 months or greater, Fair value		44,048
Unrealized losses 12 months or greater, Unrealized losses		(904)
Fair value, Total	74,912	104,700
Unrealized losses, Total	(148)	(1,033)
US Government Agency Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	6,950
Unrealized losses less than 12 months, Unrealized losses	(4)
Fair value, Total	6,950
Unrealized losses, Total	(4)
Corporate Debt Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	748	2,560
Unrealized losses less than 12 months, Unrealized losses		(8)
Fair value, Total	748	2,560
Unrealized losses, Total		(8)
Commercial Paper
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	22,944
Unrealized losses less than 12 months, Unrealized losses	(10)
Fair value, Total	22,944
Unrealized losses, Total	$ (10)
Supranational Debt Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value		639
Unrealized losses less than 12 months, Unrealized losses		(6)
Fair value, Total		639
Unrealized losses, Total		$ (6)

Marketable Securities - Additio

Marketable Securities - Additional Information (Details)	Dec. 31, 2023 USD ($) Position	Dec. 31, 2022 USD ($) Position
Investments, Debt and Equity Securities [Abstract]
Available of sale securities, unrealized loss position, Number of positions | Position	22	35
Available for sale securities, gross unrealized loss position	$ 105,554,000	$ 107,899,000
Available of sale securities, unrealized loss position, greater than 12 months, Number of positions | Position	0	10
Available of sale securities, unrealized loss position, greater than 12 months		$ 44,048,000
Available-for-sale securities, accrued interest	$ 1,100,000	$ 748,000
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Current, Statement of Financial Position [Extensible Enumeration]	Prepaid Expense and Other Assets, Current	Prepaid Expense and Other Assets, Current

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property and equipment	$ 29,559	$ 28,315
Less accumulated depreciation and amortization	(7,232)	(3,500)
Property and equipment, net	22,327	24,815
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment	5,620	4,815
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment	4,099	4,104
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	18,173	17,837
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	$ 1,667	$ 1,559

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 3,732	$ 2,641

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 8,803	$ 11,523
Accrued compensation	10,311	9,395
Unvested early exercised stock option liability	464	1,690
Accrued professional services	435	873
Accrued property and equipment	13	638
Other accruals	160	217
Total	$ 20,186	$ 24,336

Asset Acquisitions - Additional

Asset Acquisitions - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Mar. 31, 2021	Nov. 30, 2020	Dec. 31, 2023	Dec. 31, 2022
Asset Acquisition [Line Items]
In-process research and development				$ 102,000,000
Asana Merger Agreement
Asset Acquisition [Line Items]
Upfront payment made		$ 20,000,000
Future development and regulatory milestone cash payments maximum		$ 90,000,000
Additional shares required to issue upon achieving development milestone		3,888,889
In-process research and development			$ 0	0
Milestones accrued			0	0
Asana Merger Agreement | Series B-2 Convertible Preferred Stock
Asset Acquisition [Line Items]
Shares issued		4,000,000
Value per share		$ 7.50
Total fair value of equity		$ 30,000,000
Asana Merger Agreement | Series B-2 Convertible Preferred Stock | Common Stock | IPO
Asset Acquisition [Line Items]
Convertible preferred stock converted into shares of common stock		3,333,333
ELS Purchase Agreement
Asset Acquisition [Line Items]
Upfront payment made	$ 2,000,000
In-process research and development			$ 0	$ 0
ELS Purchase Agreement | Common Stock
Asset Acquisition [Line Items]
Shares issued	500,000
Value per share	$ 3.36
Total fair value of equity	$ 1,700,000

License Agreements - Additional

License Agreements - Additional Information (Details) - USD ($)	1 Months Ended									12 Months Ended
	Dec. 31, 2022	Mar. 31, 2022	Aug. 31, 2021	May 31, 2021	Jan. 31, 2021	Apr. 30, 2020	Mar. 31, 2020	Feb. 29, 2020	Dec. 31, 2018	Dec. 31, 2023	Dec. 31, 2022
License Agreements [Line Items]
In-process research and development											$ 102,000,000
Accounts payable	$ 23,049,000									$ 2,000,000	23,049,000
License Agreement | Novartis Pharma AG
License Agreements [Line Items]
Upfront payment	20,000,000
In-process research and development										0	100,000,000
Accrued milestone payment as underlying contingencies	0									0	0
Stock issued, value	$ 80,000,000
Stock issued and sold	12,307,692
Accounts payable	$ 20,000,000									0	20,000,000
License Agreement | Novartis Pharma AG | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation	80,000,000
Sales milestone payments obligation	200,000,000
License Agreement | NiKang Therapeutics, Inc.
License Agreements [Line Items]
Upfront payment								$ 5,000,000
Reimbursement of certain initial manufacturing costs								400,000
Payment for US patent application						$ 7,000,000
In-process research and development										0	0
Accrued milestone payment as underlying contingencies	0									0	0
License Agreement | NiKang Therapeutics, Inc. | First Licensed Product
License Agreements [Line Items]
Payment of development and regulatory milestone obligation					$ 4,000,000
License Agreement | NiKang Therapeutics, Inc. | First Licensed Product | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation								16,000,000
Commercial milestone payments obligation								157,000,000
License Agreement | NiKang Therapeutics, Inc. | Second Licensed Product
License Agreements [Line Items]
Development and regulatory milestone payments obligation								12,000,000
Commercial milestone payments obligation								$ 151,000,000
License Agreement | Katmai Pharmaceuticals, Inc.
License Agreements [Line Items]
Upfront payment							$ 5,700,000
Payment of development and regulatory milestone obligation		$ 2,000,000
In-process research and development										0	2,000,000
Accrued milestone payment as underlying contingencies	0									0	0
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-1 Convertible Preferred Stock and Series B-2 Convertible Preferred Stock
License Agreements [Line Items]
Stock issued, value							$ 2,700,000
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-1 Convertible Preferred Stock and Series B-2 Convertible Preferred Stock | IPO
License Agreements [Line Items]
Conversion of convertible preferred stock into common stock							395,555
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-1 Convertible Preferred Stock
License Agreements [Line Items]
Stock issued, value						$ 1,800,000
Stock issued and sold						356,000
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-2 Convertible Preferred Stock
License Agreements [Line Items]
Stock issued, value					$ 900,000
Stock issued and sold					118,666
License Agreement | Katmai Pharmaceuticals, Inc. | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation							$ 26,000,000
Commercial milestone payments obligation							$ 101,000,000
License Agreement | LifeArc
License Agreements [Line Items]
Upfront payment						$ 0
In-process research and development										0	0
Accrued milestone payment as underlying contingencies	0									0	0
One-time license payment						75,000
License Agreement | LifeArc | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation						11,000,000
Sales milestone payments obligation						$ 50,000,000
License Agreement | The Regents
License Agreements [Line Items]
Upfront payment									$ 50,000
In-process research and development										0	0
Accrued milestone payment as underlying contingencies	$ 0									$ 0	$ 0
Sales milestone payments obligation									$ 2,000,000
Percentage of third tier sublicensing fees									30%
Cash payments in license agreement upon achievement of corporate milestone			$ 1,700,000
License Agreement | The Regents | Common Stock
License Agreements [Line Items]
Stock issued and sold				944,945
License Agreement | The Regents | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation									$ 6,400,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Dec. 31, 2022	Aug. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2018	Dec. 31, 2021
Class of Stock [Line Items]
Common stock, shares authorized	800,000,000		800,000,000	800,000,000
Undesignated preferred stock authorized	80,000,000		80,000,000	80,000,000
Undesignated preferred stock par value	$ 0.0001		$ 0.0001	$ 0.0001
Common stock, shares issued	150,448,363		151,462,103	150,448,363
Common stock, shares outstanding	149,333,258		151,090,227	149,333,258
Common stock, voting rights			one vote for each share held
Common stock, dividends declared			$ 0
Shares of common stock subject to repurchase	0		0	0
Share-based compensation, vesting rights description			The restricted stock vests 25% one year from the vesting commencement date and monthly thereafter over a three-year period and is subject to repurchase by the Company in the event of any voluntary or involuntary termination of services to the Company prior to vesting.
Net proceeds from offering				$ 95,251
Common Stock
Class of Stock [Line Items]
Common stock, shares issued	150,448,363		151,462,103	150,448,363		121,382,547
2022 Registered Direct Offering | Common Stock
Class of Stock [Line Items]
Stock issued and sold	15,384,616
Price per share	$ 6.5			$ 6.5
Net proceeds from offering	$ 94,900
Offering costs	$ 5,100
Restricted Stock
Class of Stock [Line Items]
Shares issued					1,458,332
Share price per share					$ 0.0001
Stock vesting period					3 years
Number of shares of common stock subject to repurchase vested in period			0	212,674
Restricted Stock | One Year from the Vesting Commencement Date and Monthly Thereafter Over Three-year Vesting Period
Class of Stock [Line Items]
Stock vesting percentage					25%
Jefferies LLC | Common Stock
Class of Stock [Line Items]
Number of stock sold			0
Jefferies LLC | Maximum | Common Stock
Class of Stock [Line Items]
Aggregate offering price		$ 200,000
Percentage of commission on gross sales proceeds		3%

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	5 Months Ended	12 Months Ended
	Jul. 31, 2021	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			42,394,435	34,381,274
Share-based compensation, shares subject to repurchase			371,876	1,115,105
Stock-based compensation			$ 26,231,000	$ 20,109,000
Accrued Expenses and Other Current Liabilities
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, liabilities associated with shares issued with repurchase rights			$ 464,000	$ 1,700,000
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, common stock grant in period, term			5 years
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			24,970,957	17,393,396
Stock vesting period			4 years
Weighted-average grant date fair value of options granted			$ 2.7	$ 7.43
Unrecognized compensation cost related to unvested stock option grants			$ 50,400,000
Unrecognized compensation cost expected to be recognized as expense, period			2 years 5 months 4 days
Intrinsic value of options exercised			$ 1,200,000	$ 7,800,000
Share-based compensation, options granted that vest based on performance milestone			12,038,837
Employee Stock Option | Minimum | At the Time Option is Granted
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock			100%
Employee Stock Option | Minimum | For Holders of More Than 10% of Company's Total Combined Voting Power of All Classes of Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock			110%
Employee Stock Option | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, plan expiration period			10 years
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, options granted that vest based on performance milestone		0
2021 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			15,342,797
Shares of common stock, authorized for issuance	15,150,000
Percentage of outstanding common stock maximum	5%
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,260,000
Unrecognized compensation cost related to unvested stock option grants			$ 1,900,000
Unrecognized compensation cost expected to be recognized as expense, period			1 year 11 months 8 days
Stock-based compensation			$ 1,500,000	1,100,000
Share-based payment arrangement, withheld on behalf of employees for future purchase			$ 46,000	$ 74,000
Offering period	24 months
Purchase period	6 months
Shares issued under ESPP			388,933	202,882
ESPP | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock	85%

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock Option Activity (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Outstanding at December 31, 2022	17,393,396
Shares Granted	12,038,837
Shares Exercised	(624,807)
Shares Canceled	(3,836,469)
Shares Outstanding at December 31, 2023	24,970,957	17,393,396
Shares Options exercisable at December 31, 2023	11,270,914
Weighted-average exercise price, Outstanding at December 31, 2022	$ 5.84
Weighted-average exercise price, Granted	3.67
Weighted-average exercise price, Exercised	0.81
Weighted-average exercise price, Canceled	5.44
Weighted-average exercise price, Outstanding at December 31, 2023	4.98	$ 5.84
Weighted-average exercise price, Options exercisable at December 31, 2023	$ 4.83
Weighted-average remaining contractual term (years), Outstanding	8 years 1 month 13 days	8 years 2 months 12 days
Weighted-average remaining contractual term (years), Options exercisable at December 31, 2023	7 years 4 months 24 days
Aggregate intrinsic value, Outstanding	$ 4,412	$ 18,295
Aggregate intrinsic value, Options exercisable at December 31, 2023	$ 4,017

Stock-based Compensation - Assu

Stock-based Compensation - Assumptions used to Determine Fair Value of Stock Option Grants and Stock to be Purchased under ESPP (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate, minimum	3.46%	1.46%
Risk-free interest rate, maximum	4.73%	4.23%
Expected volatility, minimum	82.01%	83.91%
Expected volatility, maximum	85.81%	87.11%
Expected dividend yield	0%	0%
Employee Stock Option | Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years 6 months
Employee Stock Option | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 29 days
ESPP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate, minimum	4.43%	2.24%
Risk-free interest rate, maximum	5.36%	4.68%
Expected volatility, minimum	70%	73.05%
Expected volatility, maximum	82.79%	87.89%
Expected dividend yield	0%	0%
ESPP | Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	5 months 26 days	6 months
ESPP | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	1 year 11 months 26 days	1 year 11 months 26 days

Stock-based Compensation - Sche

Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 26,231	$ 20,109
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	13,972	11,620
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 12,259	$ 8,489

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	42,394,435	34,381,274
Stock Options Issued and Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	24,970,957	17,393,396
Awards Available for Future Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	15,342,797	16,022,747
Shares Available for Purchase Under ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	2,080,681	965,131

Leases - Additional Information

Leases - Additional Information (Details)	1 Months Ended				12 Months Ended
	Apr. 30, 2022	Dec. 31, 2021 USD ($) ft²	Mar. 31, 2021 ft²	Sep. 30, 2020 USD ($) ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Lessee Lease Description [Line Items]
Operating leases cancelable and non-cancellable expiration dates					2032
Operating leases Noncancelable expiration dates					2026
Total lease cost					$ 11,400,000	$ 7,700,000
Operating lease cost					7,700,000	5,800,000
Variable lease costs					3,700,000	1,800,000
Short-term lease costs					0	86,000
Cash paid for operating leases					$ 6,900,000	$ 1,200,000
Operating lease, weighted-average remaining lease term					8 years 3 months 14 days	9 years 3 months 3 days
Operating lease, weighted-average discount rate					8.95%	8.96%
Operating lease, aggregate monthly payments to lessor					$ 80,520,000
Letter of credit provided to lessor					$ 408,000	$ 408,000
2020 Lease
Lessee Lease Description [Line Items]
Office space leases | ft²				59,407
Lease commencement month and year				2021-08
Operating lease initial term				10 years 9 months
Operating lease, aggregate monthly payments to lessor				$ 51,600,000
Tenant improvement allowance				$ 16,800,000
Term for cancellation of lease				84 months
Notice period for cancellation of lease				12 months
Operating lease cancellation payment				$ 2,500,000
2020 Lease | Letter of Credit
Lessee Lease Description [Line Items]
Letter of credit provided to lessor				$ 408,000
Line of credit facility, expiration date				Jul. 29, 2032
First Amendment to 2020 Lease
Lessee Lease Description [Line Items]
Office space leases | ft²			18,421
Lease commencement month and year	2022-05		2022-02
2021 Lease
Lessee Lease Description [Line Items]
Office space leases | ft²		29,542
Lease commencement month and year		2022-07
Operating lease initial term		124 months
Operating lease option to extend					5 years
Operating lease existence of option to extend [true false]					true
Operating lease, aggregate monthly payments to lessor		$ 34,400,000
Tenant improvement allowance		8,200,000
Prepaid rent						$ 5,100,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]						Operating Lease, Right-of-Use Asset
2021 Lease | Other Assets
Lessee Lease Description [Line Items]
Security deposit paid		$ 874,000

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments under Operating Leases (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Leases [Abstract]
2024	$ 8,752
2025	9,024
2026	9,170
2027	9,199
2028	9,277
Thereafter	35,098
Total lease payments	80,520
Less: Amount representing interest	(24,661)
Operating lease liabilities	$ 55,859

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Provision for federal income taxes	$ 0	$ 0
Provision for state income taxes	0	0
Provision for foreign income taxes	0	0
Deferred tax assets, valuation allowance	143,833,000	130,153,000
Deferred tax assets, increase in valuation allowance	$ 13,700,000
Minimum stock holding percentage for ownership change	50%
Stock holding period for ownership change	3 years
Unrecognized tax benefits that, if recognized, would reduce annual effective tax rate	$ 3,800,000
Interest or penalties related to income taxes	0	$ 0
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	$ 200,900,000
Net operating loss carryforwards offset percentage	80%
Charitable contribution carryforward amount	$ 15,500,000
Federal | Research
Income Taxes [Line Items]
Tax credit carryforwards	$ 12,100,000
Tax credit carryforward expiration year	2038
Federal | Orphan Drug Credit
Income Taxes [Line Items]
Tax credit carryforwards	$ 535,000
Tax credit carryforward expiration year	2043
Other State
Income Taxes [Line Items]
Net operating loss carryforwards	$ 2,500,000
Net operating loss carryforwards expiration year	2035
California
Income Taxes [Line Items]
Net operating loss carryforwards	$ 243,100,000
Net operating loss carryforwards expiration year	2038
Charitable contribution carryforward expiration year	2024
California | Research
Income Taxes [Line Items]
Tax credit carryforwards	$ 7,100,000
MASSACHUSETTS | Research
Income Taxes [Line Items]
Tax credit carryforwards	$ 554,000
Tax credit carryforward expiration year	2036

Income Taxes - Schedule of Sign

Income Taxes - Schedule of Significant Portions of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 59,326	$ 52,470
Intangible assets	25,274	36,195
Capitalized research and development costs	35,711	21,004
Operating lease liabilities	11,767	15,451
Research and development credits	14,956	9,853
Contribution of common stock	3,262	4,907
Stock-based compensation	4,007	3,961
Other, net	2,016	3,455
Total deferred tax assets	156,319	147,296
Deferred tax liabilities:
Property and equipment	(4,511)	(5,809)
Operating lease assets	(7,975)	(11,334)
Total deferred tax liabilities	(12,486)	(17,143)
Valuation allowance	(143,833)	(130,153)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Federal Statutory Income Tax Rate and Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate	21%	21%
State income taxes, net of federal benefit	(9.80%)	7.60%
Change in valuation allowance	(11.10%)	(30.30%)
Other permanent differences	(1.60%)	(0.30%)
Research and Development credits	5%	2.90%
State net operating loss	(0.40%)	(0.10%)
Other	(3.10%)	(0.80%)
Effective income tax rate	0%	0%

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 2,725	$ 1,182
Increase related to prior year positions	99	0
Increase related to current year positions	1,272	1,543
Balance at the end of the year	$ 4,096	$ 2,725

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net Income (Loss)	$ (125,042)	$ (242,805)
Weighted-average shares of common stock used in computing net loss per share, basic	150,184,994	122,024,848
Weighted-average shares of common stock used in computing net loss per share, diluted	150,184,994	122,024,848
Net loss per share, basic	$ (0.83)	$ (1.99)
Net loss per share, diluted	$ (0.83)	$ (1.99)

Net Loss Per Share - Anti-dilut

Net Loss Per Share - Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	26,644,038	19,312,268
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	24,970,957	17,393,396
Options Early Exercised Subject to Future Vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	371,876	1,115,105
Estimated Shares Purchasable Under the ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	1,301,205	803,767

Retirement Plan - Additional In

Retirement Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Safe harbor contribution percentage	3%
Safe harbor contribution expense	$ 958,000	$ 858,000

CARES Act - Additional Informat

CARES Act - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Risks and Uncertainties [Abstract]
Credit percentage on qualified wages on employment taxes		70%	50%
Employee retention credit	$ 2.2

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Erasca Foundation
Related Party Transaction [Line Items]
Amount loaned in exchange of non-interest bearing promissory note	$ 125,000	$ 0	$ 0
Affini T Therapeutics, Inc.
Related Party Transaction [Line Items]
Investment in equity securities		$ 2,000,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Subsequent Event		2 Months Ended
	Jan. 31, 2024 ft²	Feb. 29, 2024 $ / shares shares
2024 Lease
Subsequent Event [Line Items]
Office space leases | ft²	10,000
Lease initial term	3 years
Operating sublease existence of option to extend [true false]	true
Operating sublease existence of option to terminate [true false]	true
Options to Purchase Common Stock
Subsequent Event [Line Items]
Shares Granted | shares		9,827,650
Weighted-average exercise price, Granted | $ / shares		$ 1.71