Erasca (ERAS) 10-Q 12 Aug 24 2024 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Aug. 05, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Entity Registrant Name	ERASCA, INC.
Entity Central Index Key	0001761918
Current Fiscal Year End Date	--12-31
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 Current Reporting Status	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		282,504,318
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	ERAS
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 172,802,000	$ 93,075,000
Short-term marketable securities	235,610,000	219,275,000
Prepaid expenses and other current assets	9,593,000	8,326,000
Total current assets	418,005,000	320,676,000
Long-term marketable securities	51,836,000	9,642,000
Property and equipment, net	17,990,000	22,327,000
Operating lease assets	33,546,000	37,861,000
Restricted cash	408,000	408,000
Other assets	3,959,000	4,383,000
Total assets	525,744,000	395,297,000
Current liabilities:
Accounts payable	2,142,000	2,000,000
Accrued expenses and other current liabilities	18,465,000	20,186,000
Operating lease liabilities	4,286,000	3,970,000
Total current liabilities	24,893,000	26,156,000
Operating lease liabilities, net of current portion	49,682,000	51,889,000
Other liabilities	82,000	566,000
Total liabilities	74,657,000	78,611,000
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock, $0.0001 par value; 80,000,000 shares authorized at June 30, 2024 and December 31, 2023; no shares issued and outstanding at June 30, 2024 and December 31, 2023
Common stock, $0.0001 par value; 800,000,000 shares authorized at June 30, 2024 and December 31, 2023; 273,163,958 and 151,462,103 shares issued at June 30, 2024 and December 31, 2023, respectively; 273,039,997 and 151,090,227 shares outstanding at June 30, 2024 and December 31, 2023, respectively	27,000	15,000
Additional paid-in capital	1,155,487,000	922,607,000
Accumulated other comprehensive (loss) income	(196,000)	77,000
Accumulated deficit	(704,231,000)	(606,013,000)
Total stockholders' equity	451,087,000	316,686,000
Total liabilities and stockholders' equity	$ 525,744,000	$ 395,297,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023
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	273,163,958	151,462,103
Common stock, shares outstanding	273,039,997	151,090,227

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating expenses:
Research and development	$ 33,032	$ 26,218	$ 61,606	$ 53,803
In-process research and development	22,500		22,500
General and administrative	12,250	9,752	22,527	19,192
Total operating expenses	67,782	35,970	106,633	72,995
Loss from operations	(67,782)	(35,970)	(106,633)	(72,995)
Other income (expense)
Interest income	5,041	4,251	8,941	8,128
Other expense, net	(460)	(62)	(526)	(113)
Total other income (expense), net	4,581	4,189	8,415	8,015
Net loss	$ (63,201)	$ (31,781)	$ (98,218)	$ (64,980)
Net loss per share, basic	$ (0.29)	$ (0.21)	$ (0.53)	$ (0.43)
Net loss per share, diluted	$ (0.29)	$ (0.21)	$ (0.53)	$ (0.43)
Weighted-average shares of common stock used in computing net loss per share, basic	217,806,567	150,037,029	184,484,154	149,772,093
Weighted-average shares of common stock used in computing net loss per share, diluted	217,806,567	150,037,029	184,484,154	149,772,093
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities, net	$ 14	$ (279)	$ (273)	$ 248
Comprehensive loss	$ (63,187)	$ (32,060)	$ (98,491)	$ (64,732)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Private Placement	Underwritten Offering	Common Stock	Common Stock Private Placement	Common Stock Underwritten Offering	Additional Paid-in Capital	Additional Paid-in Capital Private Placement	Additional Paid-in Capital Underwritten Offering	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance, shares at Dec. 31, 2022				150,448,363
Beginning balance at Dec. 31, 2022	$ 411,853			$ 15			$ 893,850			$ (1,041)	$ (480,971)
Exercise of stock options, shares				199,344
Exercise of stock options	183						183
Vesting of early exercised stock options	243						243
Stock-based compensation expense	6,845						6,845
Net loss	(33,199)										(33,199)
Unrealized gain (loss) on marketable securities, net	527									527
Ending balance, shares at Mar. 31, 2023				150,647,707
Ending balance at Mar. 31, 2023	386,452			$ 15			901,121			(514)	(514,170)
Beginning balance, shares at Dec. 31, 2022				150,448,363
Beginning balance at Dec. 31, 2022	411,853			$ 15			893,850			(1,041)	(480,971)
Net loss	(64,980)
Ending balance, shares at Jun. 30, 2023				151,042,118
Ending balance at Jun. 30, 2023	362,705			$ 15			909,434			(793)	(545,951)
Beginning balance, shares at Mar. 31, 2023				150,647,707
Beginning balance at Mar. 31, 2023	386,452			$ 15			901,121			(514)	(514,170)
Exercise of stock options, shares				170,715
Exercise of stock options	122						122
Issuance of common stock under the Employee Stock Purchase Plan	527						527
Issuance of common stock under the Employee Stock Purchase Plan, Shares				223,696
Vesting of early exercised stock options	652						652
Stock-based compensation expense	7,012						7,012
Net loss	(31,781)										(31,781)
Unrealized gain (loss) on marketable securities, net	(279)									(279)
Ending balance, shares at Jun. 30, 2023				151,042,118
Ending balance at Jun. 30, 2023	$ 362,705			$ 15			909,434			(793)	(545,951)
Beginning balance, shares at Dec. 31, 2023	151,462,103			151,462,103
Beginning balance at Dec. 31, 2023	$ 316,686			$ 15			922,607			77	(606,013)
Exercise of stock options, shares				35,035
Exercise of stock options	24						24
Vesting of early exercised stock options	155						155
Stock-based compensation expense	6,848						6,848
Net loss	(35,017)										(35,017)
Unrealized gain (loss) on marketable securities, net	(287)									(287)
Ending balance, shares at Mar. 31, 2024				151,497,138
Ending balance at Mar. 31, 2024	$ 288,409			$ 15			929,634			(210)	(641,030)
Beginning balance, shares at Dec. 31, 2023	151,462,103			151,462,103
Beginning balance at Dec. 31, 2023	$ 316,686			$ 15			922,607			77	(606,013)
Net loss	$ (98,218)
Ending balance, shares at Jun. 30, 2024	273,163,958			273,163,958
Ending balance at Jun. 30, 2024	$ 451,087			$ 27			1,155,487			(196)	(704,231)
Beginning balance, shares at Mar. 31, 2024				151,497,138
Beginning balance at Mar. 31, 2024	288,409			$ 15			929,634			(210)	(641,030)
Issuance of common stock		$ 43,604	$ 174,426		$ 2	$ 10		$ 43,602	$ 174,416
Issuance of common stock, share					21,844,660	99,459,458
Exercise of stock options, shares				110,258
Exercise of stock options	105						105
Issuance of common stock under the Employee Stock Purchase Plan	395						395
Issuance of common stock under the Employee Stock Purchase Plan, Shares				252,444
Vesting of early exercised stock options	155						155
Stock-based compensation expense	7,180						7,180
Net loss	(63,201)										(63,201)
Unrealized gain (loss) on marketable securities, net	$ 14									14
Ending balance, shares at Jun. 30, 2024	273,163,958			273,163,958
Ending balance at Jun. 30, 2024	$ 451,087			$ 27			$ 1,155,487			$ (196)	$ (704,231)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Jun. 30, 2024 USD ($)
Private Placement
Issuance of common stock, costs	$ 1,396
Underwritten Offering
Issuance of common stock, costs	$ 9,574

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Cash flows from operating activities:
Net loss	$ (98,218,000)	$ (64,980,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,131,000	1,849,000
Stock-based compensation expense	14,028,000	13,857,000
In-process research and development expenses	22,500,000
Accretion on marketable securities, net	(4,719,000)	(2,386,000)
Impairment charge on operating lease assets and property and equipment	4,653,000
Impairment charge on investment in equity securities	402,000
Changes in operating assets and liabilities:
Prepaid expenses and other current and long-term assets	(840,000)	1,794,000
Accounts payable	(77,000)	(255,000)
Accrued expenses and other current and long-term liabilities	(2,313,000)	(5,721,000)
Operating lease assets and liabilities, net	19,000	3,533,000
Net cash used in operating activities	(62,434,000)	(52,309,000)
Cash flows from investing activities:
Purchases of marketable securities	(144,333,000)	(199,450,000)
Maturities of marketable securities	90,250,000	126,950,000
In-process research and development	(22,500,000)	(20,000,000)
Purchases of property and equipment	(55,000)	(1,453,000)
Net cash used in investing activities	(76,638,000)	(93,953,000)
Cash flows from financing activities:
Proceeds from issuance of common stock in private placement, net of fees and expenses	43,637,000
Proceeds from issuance of common stock in underwritten offering, net of discounts and offering costs	174,638,000
Proceeds from the exercise of stock options	129,000	305,000
Proceeds from issuance of common stock under the Employee Stock Purchase Plan	395,000	527,000
Net cash provided by financing activities	218,799,000	832,000
Net increase (decrease) in cash, cash equivalents and restricted cash	79,727,000	(145,430,000)
Cash, cash equivalents and restricted cash at beginning of the period	93,483,000	284,625,000
Cash, cash equivalents and restricted cash at end of the period	173,210,000	139,195,000
Supplemental disclosure of noncash investing and financing activities:
Amounts accrued for purchases of property and equipment		33,000
Vesting of early exercised options	310,000	$ 895,000
Amounts accrued for offering costs	245,000
Amounts accrued for deferred offering costs	170,000
Obligation accrued for investment in equity securities	$ 235,000

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (63,201)	$ (35,017)	$ (31,781)	$ (33,199)	$ (98,218)	$ (64,980)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On June 30, 2024 , each of Shannon Morris , M.D., Ph.D., our Chief Medical Officer , and Ebun Garner , J.D., our General Counsel , adopted a Rule 10b5-1 trading arrangement that is intended to satisfy the affirmative defense of Rule 10b5-1(c) for the sale of up to 80,000 and 200,000 shares of our common stock until March 31, 2026 and June 30, 2026 , respectively .
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
Rule 10b5-1 Arrangement Modified	false
Non-Rule 10b5-1 Arrangement Modified	false
Shannon Morris [Member]
Trading Arrangements, by Individual
Name	Shannon Morris
Title	M.D., Ph.D., our Chief Medical Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	June 30, 2024
Expiration Date	March 31, 2026
Arrangement Duration	640 days
Aggregate Available	80,000
Ebun Garner [Member]
Trading Arrangements, by Individual
Name	Ebun Garner
Title	J.D., our General Counsel
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	June 30, 2024
Expiration Date	June 30, 2026
Arrangement Duration	731 days
Aggregate Available	200,000

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2024
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 comprising 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 June 30, 2024, the Company had $ 408.4 million in cash, cash equivalents, and short-term marketable securities and $ 51.8 million in long-term marketable securities. As of June 30, 2024, the Company had an accumulated deficit of $ 704.2 million. The Company has incurred significant operating losses and negative cash flows from operations. From its inception through June 30, 2024, 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), underwritten offerings, and a private placement of common stock. 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 June 30, 2024 will be sufficient for the Company to fund operations for at least one year from the issuance date of these condensed consolidated financial statements. 2024 underwritten offering In May 2024, the Company completed the sale and issuance of 99,459,458 shares of its common stock, including the exercise in full by the underwriters of their option to purchase 12,972,972 shares of its common stock, at a price to the public of $ 1.85 per share (the 2024 Offering). Proceeds from the 2024 Offering were $ 174.4 million, net of underwriting discounts and commissions and offering costs of $ 9.6 million. 2024 private placement In March 2024, the Company entered into a stock purchase agreement with the purchasers named therein for the private placement of 21,844,660 shares of its common stock at a price of $ 2.06 per share, which closed on April 2, 2024 (the 2024 Private Placement). Proceeds from the 2024 Private Placement were $ 43.6 million, after deducting placement agent fees and expenses of approximately $ 1.4 m illion. Basis of presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with US generally accepted accounting principles (US GAAP) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (SEC). Accordingly, they do not include all of the information and notes required by US GAAP for complete financial statements. 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). The Company’s condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Erasca Australia, ASN, and Erasca Ventures. All intercompany balances and transactions have been eliminated.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of significant accounting policies Use of estimates The preparation of the Company’s condensed 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 condensed consolidated financial statements and accompanying notes. Accounting estimates and management judgments reflected in the condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, stock-based compensation expense, the fair value of long-lived assets, the fair value of equity investments 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. Unaudited interim financial information The accompanying condensed consolidated balance sheet as of June 30, 2024, the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2024 and 2023, the condensed consolidated statements of stockholders’ equity for the three and six months ended June 30, 2024 and 2023 and the condensed consolidated statements of cash flows for the six months ended June 30, 2024 and 2023 are unaudited. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s condensed consolidated financial position as of June 30, 2024 and the condensed consolidated results of its operations and cash flows for the three and six months ended June 30, 2024 and 2023. The condensed consolidated financial data and other information disclosed in these notes related to the three and six months ended June 30, 2024 and 2023 are unaudited. The condensed consolidated results for the three and six months ended June 30, 2024 are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. These unaudited condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2023 filed with the SEC on March 27, 2024 . 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 June 30, 2024 and December 31, 2023 to secure a letter of credit in connection with the lease of the Company’s facilities (see Note 10). The Company has classified the restricted cash as a noncurrent asset on its condensed consolidated balance sheets. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows (in thousands): June 30, 2024 2023 Cash and cash equivalents $ 172,802 $ 138,787 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 173,210 $ 139,195 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 14). 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 condensed 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). 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	6 Months Ended
	Jun. 30, 2024
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 June 30, 2024 using Quoted prices in Significant Significant active markets other unobservable June 30, for identical observable inputs 2024 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 169,440 $ 169,440 $ — $ — US treasury securities (2) 54,219 54,219 — — US government agency securities (2) 40,633 — 40,633 — Corporate debt securities (2) 39,597 — 39,597 — Commercial paper (2) 101,161 — 101,161 — US treasury securities (3) 29,619 29,619 — — US government agency securities (3) 22,217 — 22,217 — Total fair value of assets $ 456,886 $ 253,278 $ 203,608 $ — (1) Included as cash and cash equivalents on the condensed consolidated balance sheets. (2) Included as short-term marketable securities on the condensed consolidated balance sheets. (3) Included as long-term marketable securities on the condensed consolidated balance sheets. 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 condensed consolidated balance sheets. (2) Included as short-term marketable securities on the condensed consolidated balance sheets. (3) Included as long-term marketable securities on the condensed 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 June 30, 2024 and December 31, 2023 , the Company held $ 1.8 million and $ 2.0 million in equity investments in Affini-T Therapeutics, Inc. (Affini-T) at cost, less impairment, respectively. An impairment adjustment of $ 402,000 was made to the value of the Company’s equity investment in Affini-T during the three months ended June 30, 2024. The Company was notified by Affini-T of an extension financing in June 2024 and the terms of such financing. Accordingly, the Company reassessed the value of its equity investment in Affini-T using a market approach. This represents a Level 3 nonrecurring fair value measurement. Calculating the fair value of the equity investment involves unobservable inputs, including the terms and preferences of the extension financing, and significant estimates and assumptions. Changes in the estimates and assumptions used could materially affect the amount of impairment loss recognized in the period the equity investment is considered impaired. This impairment was offset by a new investment obligation of approximately $ 235,000 recorded as of June 30, 2024. In July 2024, the Company paid approximately $ 157,000 of the obligation related to the extension financing. 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 and commercial paper, and long-term marketable securities consist of US treasury securities and US government agency 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, and bid and/or offers.

Marketable Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Note 4. Marketable securities The following tables summarize the Company’s marketable securities accounted for as available-for-sale securities (in thousands, except years): June 30, 2024 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 54,294 $ — $ ( 75 ) $ 54,219 US government agency securities 1 or less 40,655 — ( 22 ) 40,633 Corporate debt securities 1 or less 39,656 — ( 59 ) 39,597 Commercial paper 1 or less 101,213 5 ( 57 ) 101,161 US treasury securities 1 - 2 29,611 15 ( 7 ) 29,619 US government agency securities 1 - 2 22,213 5 ( 1 ) 22,217 Total $ 287,642 $ 25 $ ( 221 ) $ 287,446 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 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 June 30, 2024 and December 31, 2023, aggregated by category and the length of time that the securities have been in a continuous loss position (in thousands): June 30, 2024 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 $ 49,730 $ ( 25 ) $ 22,280 $ ( 57 ) $ 72,010 $ ( 82 ) US government agency securities 45,875 ( 23 ) — — 45,875 ( 23 ) Corporate debt securities 39,597 ( 59 ) — — 39,597 ( 59 ) Commercial paper 73,182 ( 57 ) — — 73,182 ( 57 ) Total $ 208,384 $ ( 164 ) $ 22,280 $ ( 57 ) $ 230,664 $ ( 221 ) 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 ) As of June 30, 2024, there were 40 available-for-sale securities with an estimated fair value of $ 230.7 million in gross unrealized loss positions, of which four available-for-sale securities with an estimated fair value of $ 22.3 million were in an unrealized loss position for more than 12 months. A s 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 June 30, 2024 and December 31, 2023, 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 changes in interest rates. 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 $ 2.2 million and $ 1.1 million as of June 30, 2024 and December 31, 2023 , respectively, and was included in prepaid expenses and other current assets on the condensed consolidated balance sheets.

Property and Equipment, Net

Property and Equipment, Net	6 Months Ended
	Jun. 30, 2024
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): June 30, December 31, 2024 2023 Laboratory equipment $ 4,745 $ 5,620 Furniture and fixtures 3,712 4,099 Leasehold improvements 16,313 18,173 Computer equipment and software 1,568 1,667 Property and equipment 26,338 29,559 Less accumulated depreciation and amortization ( 8,348 ) ( 7,232 ) Property and equipment, net $ 17,990 $ 22,327 Depreciation and amortization expense related to property and equipment was $ 1.1 million and $ 2.1 million for the three and six months ended June 30, 2024 , respectively, and $ 955,000 and $ 1.8 million for the three and six months ended June 30, 2023 , respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	6 Months Ended
	Jun. 30, 2024
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): June 30, December 31, 2024 2023 Accrued research and development expenses $ 11,044 $ 8,803 Accrued compensation 6,148 10,311 Unvested early exercised stock option liability 155 464 Accrued professional services 526 435 Accrued property and equipment — 13 Accrued offering and deferred offering costs 196 — Other accruals 396 160 Total $ 18,465 $ 20,186

Asset Acquisitions

Asset Acquisitions	6 Months Ended
	Jun. 30, 2024
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 condensed 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 three and six months ended June 30, 2024 and 2023. As of June 30, 2024 and December 31, 2023 , no milestones had been accrued as the underlying contingencies were not probable or estimable.

License Agreements

License Agreements	6 Months Ended
	Jun. 30, 2024
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. No IPR&D expense was recorded during the three and six months ended June 30, 2024 and 2023. Guangzhou Joyo Pharmatech Co., Ltd In May 2024, the Company entered into an exclusive license agreement (the Joyo License Agreement) with Guangzhou Joyo Pharmatech Co., Ltd. (Joyo) under which the Company was granted an exclusive, worldwide (except mainland China, Hong Kong, and Macau), royalty-bearing license to certain patent and other intellectual property rights owned or controlled by Joyo to develop, manufacture, and commercialize certain pan-RAS inhibitors in all fields of use. The Company has an option to expand the territory of the license to include mainland China, Hong Kong and Macau by making a $ 50.0 million payment to Joyo on or prior to the first dosing of the first patient in a Phase 2 clinical trial by either the Company or Joyo, or a payment of $ 150.0 million after the first dosing of the first patient in a Phase 2 clinical trial by either the Company or Joyo and before filing a new drug application (or the foreign equivalent) by either the Company or Joyo. The Company has the right to sublicense (through multiple tiers) its rights under the Joyo License Agreement, subject to certain limitations and conditions, and is required to use commercially reasonable efforts to commercialize licensed products in the United States. The license granted under the Joyo License Agreement is subject to Joyo’ reserved right to develop, manufacture, use, and commercialize licensed products in mainland China, Hong Kong and Macau, unless the Company exercises its option to expand the license to include mainland China, Hong Kong and Macau. Under the Joyo License Agreement, the Company made an upfront cash payment to Joyo of $ 12.5 million. The Company is obligated to make development and regulatory milestone payments of up to $ 51.5 million (or up to $ 57.5 million if the Company’s territory is expanded to include mainland China, Hong Kong, and Macau) and commercial milestone payments of up to $ 125.0 million upon the achievement of the corresponding milestones. The Company is also obligated to pay tiered royalties on net sales of all licensed products, in the low- to mid-single digit percentages, subject to certain reductions. For the three and six months ended June 30, 2024 , the Company recorded $ 12.5 million in IPR&D expense related to the upfront cash payment. The Joyo License Agreement will expire upon the last to expire royalty term, which is determined on a licensed product-by-licensed product and country-by-country basis, and is the later of: (i) ten years from the date of first commercial sale for the licensed product in such country, (ii) the last to expire valid claim within the licensed patent rights covering such licensed product, or (iii) the expiration of all regulatory exclusivity for the licensed product in such country. Upon expiration of the Joyo License Agreement, on a licensed product-by-licensed product and country-by-country basis, the license granted to the Company with respect to such product in such countries shall be deemed to be fully paid-up, royalty-free, non-terminable, irrevocable and perpetual. The Joyo License Agreement may be terminated in its entirety by either party in the event of an uncured material breach by the other party or in the event the other party becomes subject to specified bankruptcy, insolvency, or similar circumstances. Joyo may terminate the Joyo License Agreement in the event that the Company or its affiliates or any of its or their sublicensees institutes, prosecutes or otherwise participates in any challenge to the licensed patents. The Company may terminate the Joyo License Agreement in its entirety at any time upon the provision of prior written notice to Joyo. Upon termination of the Joyo License Agreement for any reason, all rights and licenses granted to the Company will terminate. In addition, the licenses granted to Joyo under certain patent and other intellectual property rights owned or controlled by the Company to develop, manufacture, use, and commercialize the licensed products in mainland China, Hong Kong and Macau will survive the termination of the Joyo License Agreement for any reason, unless the Company exercises its option to expand the license to include mainland China, Hong Kong and Macau, in which case such licenses to Joyo will terminate automatically; and Joyo has an option to negotiate a license under any patent rights, know-how, or other intellectual property rights relating to the licensed products that are owned or controlled by the Company for the purpose of developing, manufacturing and commercializing the licensed products in the Company’s territory on terms to be negotiated between the parties. Medshine Discovery Inc. In May 2024, the Company entered into an exclusive license agreement (the Medshine License Agreement) with Medshine Discovery Inc. (Medshine) under which the Company was granted an exclusive, worldwide, royalty-bearing license to certain patent and other intellectual property rights owned or controlled by Medshine to develop, manufacture, and commercialize certain pan-KRAS inhibitors in all fields of use. The Company has the right to sublicense (through multiple tiers) its rights under the Medshine License Agreement, subject to certain limitations and conditions, and is required to use commercially reasonable efforts to commercialize licensed products in certain geographical markets. Under the Medshine License Agreement, the Company made an upfront cash payment to Medshine of $ 10.0 million. The Company is obligated to make development and regulatory milestone payments of up to $ 30.0 million and commercial milestone payments of up to $ 130.0 million upon the achievement of the corresponding milestones. The Company is also obligated to pay a low-single digit percentage royalty on net sales of all licensed products, subject to certain reductions. For the three and six months ended June 30, 2024 , the Company recorded $ 10.0 million in IPR&D expense related to the upfront cash payment. The Medshine License Agreement will expire upon the last to expire royalty term, which is determined on a licensed product-by-licensed product and country-by-country basis, and is the later of: (i) ten years from the date of first commercial sale for the licensed product in such country, (ii) the last to expire valid claim within the licensed patent rights covering such licensed product, or (iii) the expiration of all regulatory exclusivity for the licensed product in such country. Upon expiration of the Medshine License Agreement, on a licensed product-by-licensed product and country-by-country basis, the license granted to the Company with respect to such product in such countries shall be deemed to be fully paid-up, royalty-free, non-terminable, irrevocable and perpetual. The Medshine License Agreement may be terminated in its entirety by either party in the event of an uncured material breach by the other party or in the event the other party becomes subject to specified bankruptcy, insolvency, or similar circumstances. Medshine may terminate the Medshine License Agreement in the event that the Company or its affiliates or any of its or their sublicensees commences or actively and voluntarily participates in any challenge to the licensed patents. The Company may terminate the Medshine License Agreement in its entirety at any time upon the provision of prior written notice to Medshine. Upon termination of the Medshine License Agreement for any reason, all rights and licenses granted to the Company will terminate. In addition, upon termination of the Medshine License Agreement by Medshine for cause, Medshine has an option to negotiate a license under any patent rights, know-how, or other intellectual property rights relating to the licensed products that are owned or controlled by the Company for the purpose of developing, manufacturing and commercializing the licensed products on terms to be negotiated between the parties. 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. No IPR&D expense was recorded during the three and six months ended June 30, 2024 and 2023. 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 three and six months ended June 30, 2024 and 2023. As of June 30, 2024 and December 31, 2023, no milestones are accrued for any license agreements as the underlying contingencies are not probable or estimable.

Stock-based Compensation

Stock-based Compensation	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	Note 9. 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 June 30, 2024, there were 12,913,020 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, 2023 24,970,957 $ 4.98 8.12 $ 4,412 Granted 11,596,445 1.76 Exercised ( 145,293 ) 0.89 Canceled ( 1,593,563 ) 3.93 Outstanding at June 30, 2024 34,828,546 $ 3.97 8.05 $ 11,579 Options exercisable at June 30, 2024 15,155,782 $ 4.70 6.83 $ 5,433 The weighted-average grant date fair value of options granted for the three and six months ended June 30, 2024 was $ 1.48 and $ 1.28 , respectively, and for the three and six months ended June 30, 2023 was $ 2.05 and $ 2.83 , respectively. As of June 30, 2024, the unrecognized compensation cost related to unvested stock option grants was $ 47.4 million and is expected to be recognized as expense over approximately 2.67 years. The intrinsic value of the options exercised for the three and six months ended June 30, 2024 was $ 123,000 and $ 170,000 , respectively. The intrinsic value of the options exercised for the three and six months ended June 30, 2023 was $ 376,000 and $ 893,000 , 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 condensed consolidated balance sheets and will be transferred into common stock and additional paid-in capital as the shares vest. As of June 30, 2024 and December 31, 2023, there were 123,961 shares and 371,876 shares subject to repurchase by the Company, respectively. As of June 30, 2024 and December 31, 2023, the Company recorded $ 155,000 and $ 464,000 of 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: Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Risk-free interest rate 4.26 %- 4.64 % 3.50 %- 3.98 % 3.84 %- 4.64 % 3.46 %- 4.22 % Expected volatility 82.72 %- 83.14 % 83.20 %- 85.02 % 82.72 %- 83.91 % 83.20 %- 85.81 % Expected term (in years) 5.50 - 6.08 5.50 - 6.08 5.28 - 6.08 5.50 - 6.08 Expected dividend yield - -% - -% - -% - -% Effective May 21, 2024, and in accordance with the terms of the 2021 Plan, the Company's board of directors approved a stock option repricing (the Option Repricing) whereby the exercise price of each Repriced Option (as defined below) was reduced to $ 2.35 per share, the closing stock price on May 21, 2024. For purposes of the Option Repricing, “Repriced Options” are 7,478,918 outstanding stock options as of May 21, 2024 (vested and unvested) granted under the 2021 Plan and held by those eligible employees of the Company identified by the Company's board of directors, excluding the Company’s Section 16 officers (the Chairman and Chief Executive Officer, the Chief Financial Officer and Chief Business Officer, the Chief Medical Officer, and the General Counsel) and the Company's board of directors. To the extent a Repriced Option is exercised prior to the Premium End Date (as defined below), the eligible employee will be required to pay the original exercise price per share of the Repriced Options in connection with any exercise of the Repriced Option. The “Premium End Date” means the earliest of (i) May 21, 2026; (ii) the date of a change in control of the Company; (iii) the date of the eligible employee’s death or disability; or (iv) the date of the eligible employee’s termination without cause, provided that such termination without cause occurs after May 21, 2025. Except for the reduction in the exercise prices of the Repriced Options as described above, the Repriced Options will retain their existing terms and conditions as set forth in the 2021 Plan and the applicable award agreements. All repriced options will retain their original vesting schedule. The Option Repricing resulted in $ 1.1 million of incremental cost, which was calculated using the Black-Scholes option pricing model, of which $ 559,000 of the incremental cost will be recognized on a straight-line basis through the Premium End Date, and $ 558,000 of the incremental cost will be recognized on a straight-line basis over the greater of the period through the Premium End Date or the remaining service period. The incremental cost is included in general and administrative expense and research and development expense on the condensed consolidated statements of operations and comprehensive loss. Employee stock purchase plan In July 2021, the Company’s board of directors adopted and the Company’s stockholders approved the Company's 2021 Employee Stock Purchase Plan (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 $ 103,000 and $ 444,000 during the three and six months ended June 30, 2024, respectively, and $ 349,000 and $ 1.1 million during the three and six months ended June 30, 2023, respectively. As of June 30, 2024, the unrecognized compensation cost related to the ESPP was $ 1.0 million and is expected to be recognized as expense over approximately 1.47 years. As of June 30, 2024 and December 31, 2023, $ 43,000 and $ 46,000 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 condensed consolidated balance sheets. The Company issued and sold 252,444 shares under the ESPP during the three and six months ended June 30, 2024 and 223,696 shares under the ESPP during the three and six months ended June 30, 2023. 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: Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Risk-free interest rate 4.75 %- 5.39 % 4.70 %- 5.35 % 4.75 %- 5.39 % 4.70 %- 5.35 % Expected volatility 68.73 %- 74.72 % 72.54 %- 82.79 % 68.73 %- 74.72 % 72.54 %- 82.79 % Expected term (in years) 0.49 - 1.99 0.50 - 1.99 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): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Research and development $ 3,788 $ 3,867 $ 7,272 $ 7,747 General and administrative 3,392 3,145 6,756 6,110 Total $ 7,180 $ 7,012 $ 14,028 $ 13,857 Common stock reserved for future issuance Common stock reserved for future issuance consisted of the following as of June 30, 2024 and December 31, 2023: June 30, December 31, 2024 2023 Stock options issued and outstanding 34,828,546 24,970,957 Awards available for future grant 12,913,020 15,342,797 Shares available for purchase under the ESPP 1,828,237 2,080,681 Total 49,569,803 42,394,435

Leases

Leases	6 Months Ended
	Jun. 30, 2024
Leases [Abstract]
Leases	Note 10. Leases Operating leases The Company has facility leases for office space under non-cancellable and cancellable 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 $ 3.2 million and $ 5.9 million, including operating lease costs of $ 2.4 million and $ 4.3 million, variable lease costs of $ 918,000 and $ 1.8 million, and sublease income of $ 132,000 and $ 216,000, durin g the three and six months ended June 30, 2024, respectively. Total lease costs were approximately $ 2.8 million and $ 5.8 million, including operating lease costs of $ 1.9 million and $ 3.8 million and variable lease costs of $ 859,000 and $ 2.0 million, durin g the three and six months ended June 30, 2023, respectively. The Company paid $ 4.1 million and $ 2.6 million in cash for operating leases, net of sublease income, that is included in the operating activities section of the condensed consolidated statements of cash flows for the six months ended June 30, 2024 and 2023, respectively. The weighted-average remaining lease term and the weighted-average discount rate of the Company’s operating leases were 7.81 years and 8.96 %, respectively, at June 30, 2024 . 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 %, respectively, at December 31, 2023. 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 . T he 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 condensed 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 condensed consolidated balance sheets and as a cash outflow from operating activities in the condensed 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 condensed consolidated balance sheets. In January 2024, the Company entered into an agreement to sublease the second floor of its corporate headquarters in San Diego, California. Pursuant to the agreement, the subleased space is approximately 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. The Company determined the sublease to be an operating lease. Therefore, the Company recognizes sublease income on a straight-line basis over the lease term in its condensed consolidated statements of operations and comprehensive loss as a reduction to operating lease costs because the sublease is outside of the Company's normal business operations. The Company will continue to account for the operating lease asset and related liability of the original lease as it did prior to the commencement of the sublease. The Company recorded a reduction to operating lease costs of $ 132,000 and $ 216,000 related to income from this sublease during the three and six months ended June 30, 2024, respectively. In June 2024, the Company committed to a plan to sublease the first floor of its corporate headquarters in San Diego, California and in July 2024, the Company executed an agreement to sublease such space. Pursuant to the agreement, the subleased space is approximately 18,421 square feet of office space with a sublease term of 61 months beginning in October 2024, with early access in August 2024. The agreement includes an option for the subtenant to renew for an additional year and an early termination clause. In connection with the sublease plan of the first floor, the Company reassessed its asset groups for testing long-lived assets for impairment and determined the first floor operating lease assets and related property and equipment represented an asset group separate from the entity wide asset group. The Company concluded that the carrying value of the first floor asset group was not recoverable as it exceeded the future net undiscounted cash flows that are expected to be generated from the use and eventual disposition of the assets within the asset group. The Company determined the fair value of the first floor asset group based on the income approach using a discounted cash flow model. The cash flows used in the model were discounted using a rate of 13.5 %. Based on this analysis, the Company recognized a noncash impairment charge of $ 4.7 million, including $ 2.4 million for the operating lease assets and $ 2.3 million for the leasehold improvements and furniture, of which $ 3.0 million was recorded to research and development expense and $ 1.7 million was recorded to general and administrative expense during the three and six months ended June 30, 2024. This represents a Level 3 nonrecurring fair value measurement. Calculating the fair value of the asset group involves significant estimates and assumptions, including projected future cash flows and a discount rate. Changes in the estimates and assumptions used could materially affect the amount of impairment loss recognized in the period the asset group is considered impaired. Future minimum lease payments under operating leases as of June 30, 2024 are as follows (in thousands): Year ending December 31, 2024 (remaining six months) $ 4,426 2025 9,024 2026 9,170 2027 9,199 2028 9,277 Thereafter 35,098 Total lease payments $ 76,194 Less: Amount representing interest ( 22,226 ) Operating lease liabilities $ 53,968

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 11. 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. Strategic reprioritization In May 2024, in connection with the execution of the Joyo License Agreement and the Medshine License Agreement, the Company approved a strategic reprioritization to focus the Company’s resources on its naporafenib program, its ERAS-0015 product candidate, which is the lead candidate from the Joyo License Agreement, and its ERAS-4001 product candidate, which is the lead candidate from the Medshine License Agreement. The Company deprioritized its HERKULES-3 clinical trial evaluating ERAS-007 in combination with encorafenib and cetuximab (EC) in patients with EC-naïve BRAFm colorectal cancer, its THUNDERBBOLT-1 clinical trial evaluating ERAS-801 in patients with recurrent glioblastoma, and its ERAS-4 pan-KRAS program. The Company will explore further advancement of the ERAS-801 program, including via select investigator-sponsored trials, and certain of the existing ERAS-4 molecules may serve as backup compounds for ERAS-4001. In connection with this strategic reprioritization, the Company also approved a reduction in the Company’s workforce by approximately 18%, primarily affecting employees working in certain drug discovery functions or on the deprioritized programs and trials. As a result, the Company recognized $ 2.2 million in total charges in the three and six months ended June 30, 2024 in the condensed consolidated statements of operations and comprehensive loss based upon the underlying employees’ role within the Company in connection with the reduction in force. These charges consisted primarily of one-time cash charges for termination benefits which were substantially all paid in June 2024.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Note 12. Income taxes No provision for federal, state or foreign income taxes has been recorded for the three and six months ended June 30, 2024 and 2023. The Company has incurred net operating losses for all the periods presented and has not reflected any benefit of such net operating loss carryforwards in the accompanying condensed consolidated financial statements due to uncertainty around utilizing these tax attributes within their respective carryforward periods. The Company has recorded a full valuation allowance against all of its deferred tax assets as it is not more likely than not that such assets will be realized in the near future. The Company’s policy is to recognize interest expense and penalties related to income tax matters as tax expense. For the three and six months ended June 30, 2024 and 2023 , the Company has no t recognized any interest or penalties related to income taxes.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	Note 13. 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): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Net loss $ ( 63,201 ) $ ( 31,781 ) $ ( 98,218 ) $ ( 64,980 ) Weighted-average shares of common stock used in computing net loss per share, basic and diluted 217,806,567 150,037,029 184,484,154 149,772,093 Net loss per share, basic and diluted $ ( 0.29 ) $ ( 0.21 ) $ ( 0.53 ) $ ( 0.43 ) 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: June 30, June 30, 2024 2023 Options to purchase common stock 34,828,546 25,519,872 Options early exercised subject to future vesting 123,961 658,857 Estimated shares purchasable under the ESPP 798,238 1,350,546 Total potentially dilutive shares 35,750,745 27,529,275

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	Note 14. Related party transactions 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. In April 2024, the Company donated $ 125,000 to the Erasca Foundation, which is recorded in general and administrative expense in the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2024. Affini-T Therapeutics, Inc. As of June 30, 2024 and December 31, 2023 , the Company held a $ 1.8 million and $ 2.0 million equity investment in Affini-T, respectively (see Note 3). One of the Company’s board members is also a member of the board of Affini-T.

Subsequent Event

Subsequent Event	6 Months Ended
	Jun. 30, 2024
Subsequent Events [Abstract]
Subsequent Event	Note 15. Subsequent event July 2024 ATM Offering From July 1, 2024 through the date of this filing, the Company sold 9,231,114 shares of common stock at a weighted average price of $ 2.37 per share under the Open Market Sale Agreement effective August 2022 (the Sale Agreement) with Jefferies LLC (the Agent). Pursuant to the Sale Agreement, the Company may offer and sell shares of its common stock having an aggregate offering price of up to $ 200 million from time to time, in “at the market” offerings (an ATM Offering) 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. Pursuant to the Sale Agreement, the Agent receives 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. Proceeds from the ATM Offering were $ 21.1 million, net of commissions and expenses of $ 0.8 million .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Use of Estimates	Use of estimates The preparation of the Company’s condensed 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 condensed consolidated financial statements and accompanying notes. Accounting estimates and management judgments reflected in the condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, stock-based compensation expense, the fair value of long-lived assets, the fair value of equity investments 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.
Unaudited Interim Financial Information	Unaudited interim financial information The accompanying condensed consolidated balance sheet as of June 30, 2024, the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2024 and 2023, the condensed consolidated statements of stockholders’ equity for the three and six months ended June 30, 2024 and 2023 and the condensed consolidated statements of cash flows for the six months ended June 30, 2024 and 2023 are unaudited. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s condensed consolidated financial position as of June 30, 2024 and the condensed consolidated results of its operations and cash flows for the three and six months ended June 30, 2024 and 2023. The condensed consolidated financial data and other information disclosed in these notes related to the three and six months ended June 30, 2024 and 2023 are unaudited. The condensed consolidated results for the three and six months ended June 30, 2024 are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. These unaudited condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2023 filed with the SEC on March 27, 2024 .
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 June 30, 2024 and December 31, 2023 to secure a letter of credit in connection with the lease of the Company’s facilities (see Note 10). The Company has classified the restricted cash as a noncurrent asset on its condensed consolidated balance sheets. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows (in thousands): June 30, 2024 2023 Cash and cash equivalents $ 172,802 $ 138,787 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 173,210 $ 139,195
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 14). 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 condensed 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).
Recently Issued Accounting Pronouncements Not Yet Adopted	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)	6 Months Ended
	Jun. 30, 2024
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 condensed consolidated balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows (in thousands): June 30, 2024 2023 Cash and cash equivalents $ 172,802 $ 138,787 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 173,210 $ 139,195

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2024
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 June 30, 2024 using Quoted prices in Significant Significant active markets other unobservable June 30, for identical observable inputs 2024 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 169,440 $ 169,440 $ — $ — US treasury securities (2) 54,219 54,219 — — US government agency securities (2) 40,633 — 40,633 — Corporate debt securities (2) 39,597 — 39,597 — Commercial paper (2) 101,161 — 101,161 — US treasury securities (3) 29,619 29,619 — — US government agency securities (3) 22,217 — 22,217 — Total fair value of assets $ 456,886 $ 253,278 $ 203,608 $ — (1) Included as cash and cash equivalents on the condensed consolidated balance sheets. (2) Included as short-term marketable securities on the condensed consolidated balance sheets. (3) Included as long-term marketable securities on the condensed consolidated balance sheets. 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 condensed consolidated balance sheets. (2) Included as short-term marketable securities on the condensed consolidated balance sheets. (3) Included as long-term marketable securities on the condensed consolidated balance sheets.

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2024
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): June 30, 2024 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 54,294 $ — $ ( 75 ) $ 54,219 US government agency securities 1 or less 40,655 — ( 22 ) 40,633 Corporate debt securities 1 or less 39,656 — ( 59 ) 39,597 Commercial paper 1 or less 101,213 5 ( 57 ) 101,161 US treasury securities 1 - 2 29,611 15 ( 7 ) 29,619 US government agency securities 1 - 2 22,213 5 ( 1 ) 22,217 Total $ 287,642 $ 25 $ ( 221 ) $ 287,446 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
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 June 30, 2024 and December 31, 2023, aggregated by category and the length of time that the securities have been in a continuous loss position (in thousands): June 30, 2024 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 $ 49,730 $ ( 25 ) $ 22,280 $ ( 57 ) $ 72,010 $ ( 82 ) US government agency securities 45,875 ( 23 ) — — 45,875 ( 23 ) Corporate debt securities 39,597 ( 59 ) — — 39,597 ( 59 ) Commercial paper 73,182 ( 57 ) — — 73,182 ( 57 ) Total $ 208,384 $ ( 164 ) $ 22,280 $ ( 57 ) $ 230,664 $ ( 221 ) 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 )

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	6 Months Ended
	Jun. 30, 2024
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): June 30, December 31, 2024 2023 Laboratory equipment $ 4,745 $ 5,620 Furniture and fixtures 3,712 4,099 Leasehold improvements 16,313 18,173 Computer equipment and software 1,568 1,667 Property and equipment 26,338 29,559 Less accumulated depreciation and amortization ( 8,348 ) ( 7,232 ) Property and equipment, net $ 17,990 $ 22,327

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	6 Months Ended
	Jun. 30, 2024
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): June 30, December 31, 2024 2023 Accrued research and development expenses $ 11,044 $ 8,803 Accrued compensation 6,148 10,311 Unvested early exercised stock option liability 155 464 Accrued professional services 526 435 Accrued property and equipment — 13 Accrued offering and deferred offering costs 196 — Other accruals 396 160 Total $ 18,465 $ 20,186

Stock-based Compensation (Table

Stock-based Compensation (Tables)	6 Months Ended
	Jun. 30, 2024
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, 2023 24,970,957 $ 4.98 8.12 $ 4,412 Granted 11,596,445 1.76 Exercised ( 145,293 ) 0.89 Canceled ( 1,593,563 ) 3.93 Outstanding at June 30, 2024 34,828,546 $ 3.97 8.05 $ 11,579 Options exercisable at June 30, 2024 15,155,782 $ 4.70 6.83 $ 5,433
Schedule of Stock-based Compensation Expense	The allocation of stock-based compensation for all stock awards was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Research and development $ 3,788 $ 3,867 $ 7,272 $ 7,747 General and administrative 3,392 3,145 6,756 6,110 Total $ 7,180 $ 7,012 $ 14,028 $ 13,857
Summary of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consisted of the following as of June 30, 2024 and December 31, 2023: June 30, December 31, 2024 2023 Stock options issued and outstanding 34,828,546 24,970,957 Awards available for future grant 12,913,020 15,342,797 Shares available for purchase under the ESPP 1,828,237 2,080,681 Total 49,569,803 42,394,435
ESPP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Assumptions used to Determine Fair Value of Stock Option Grants	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: Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Risk-free interest rate 4.75 %- 5.39 % 4.70 %- 5.35 % 4.75 %- 5.39 % 4.70 %- 5.35 % Expected volatility 68.73 %- 74.72 % 72.54 %- 82.79 % 68.73 %- 74.72 % 72.54 %- 82.79 % Expected term (in years) 0.49 - 1.99 0.50 - 1.99 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	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: Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Risk-free interest rate 4.26 %- 4.64 % 3.50 %- 3.98 % 3.84 %- 4.64 % 3.46 %- 4.22 % Expected volatility 82.72 %- 83.14 % 83.20 %- 85.02 % 82.72 %- 83.91 % 83.20 %- 85.81 % Expected term (in years) 5.50 - 6.08 5.50 - 6.08 5.28 - 6.08 5.50 - 6.08 Expected dividend yield - -% - -% - -% - -%

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2024
Leases [Abstract]
Schedule of Future Minimum Lease Payments under Operating Leases	Future minimum lease payments under operating leases as of June 30, 2024 are as follows (in thousands): Year ending December 31, 2024 (remaining six months) $ 4,426 2025 9,024 2026 9,170 2027 9,199 2028 9,277 Thereafter 35,098 Total lease payments $ 76,194 Less: Amount representing interest ( 22,226 ) Operating lease liabilities $ 53,968

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2024
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): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Net loss $ ( 63,201 ) $ ( 31,781 ) $ ( 98,218 ) $ ( 64,980 ) Weighted-average shares of common stock used in computing net loss per share, basic and diluted 217,806,567 150,037,029 184,484,154 149,772,093 Net loss per share, basic and diluted $ ( 0.29 ) $ ( 0.21 ) $ ( 0.53 ) $ ( 0.43 )
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: June 30, June 30, 2024 2023 Options to purchase common stock 34,828,546 25,519,872 Options early exercised subject to future vesting 123,961 658,857 Estimated shares purchasable under the ESPP 798,238 1,350,546 Total potentially dilutive shares 35,750,745 27,529,275

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended
	Apr. 02, 2024	May 31, 2024	Mar. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2023
Organization And Basis Of Presentation [Line Items]
Cash, cash equivalents, and short-term marketable securities				$ 408,400
Long-term marketable securities				51,836				$ 9,642
Accumulated deficit				$ (704,231)				$ (606,013)
Private Placement
Organization And Basis Of Presentation [Line Items]
Proceeds from private placement, after deducting placement agent fees and expenses	$ 43,600
Placement agent fees and estimated expenses	$ 1,400
Underwritten Offering
Organization And Basis Of Presentation [Line Items]
Net proceeds from underwritten offering		$ 174,400
Underwriting discounts and commissions and offering costs, net		$ 9,600
Common Stock
Organization And Basis Of Presentation [Line Items]
Exercise of stock options, shares				110,258	35,035	170,715	199,344
Common Stock | Private Placement
Organization And Basis Of Presentation [Line Items]
Stock issued and sold			21,844,660	21,844,660
Price per share			$ 2.06		$ 2.06
Common Stock | Underwritten Offering
Organization And Basis Of Presentation [Line Items]
Stock issued and sold		99,459,458		99,459,458
Price per share		$ 1.85
Underwriters option to purchase additional shares		12,972,972

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Jun. 30, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Restricted cash	$ 408,000	$ 408,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 172,802	$ 93,075	$ 138,787
Restricted cash	408		408
Total cash, cash equivalents and restricted cash	$ 173,210		$ 139,195

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		Jun. 30, 2024		Dec. 31, 2023
Assets:
Total fair value of assets		$ 456,886		$ 312,018
Money Market Funds | Cash and Cash Equivalents
Assets:
Total fair value of assets		169,440	[1]	83,101	[2]
Commercial Paper | Short-Term Investments
Assets:
Total fair value of assets		101,161	[3]	88,414	[4]
US Treasury Securities | Short-Term Investments
Assets:
Total fair value of assets		54,219	[3]	93,303	[4]
US Treasury Securities | Long-Term Investments
Assets:
Total fair value of assets		29,619	[5]	9,642	[6]
US Government Agency Securities | Short-Term Investments
Assets:
Total fair value of assets		40,633	[3]	26,824	[4]
US Government Agency Securities | Long-Term Investments
Assets:
Total fair value of assets	[5]	22,217
Corporate Debt Securities | Short-Term Investments
Assets:
Total fair value of assets		39,597	[3]	10,734	[4]
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total fair value of assets		253,278		186,046
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds | Cash and Cash Equivalents
Assets:
Total fair value of assets		169,440	[1]	83,101	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | US Treasury Securities | Short-Term Investments
Assets:
Total fair value of assets		54,219	[3]	93,303	[4]
Quoted Prices in Active Markets for Identical Assets (Level 1) | US Treasury Securities | Long-Term Investments
Assets:
Total fair value of assets		29,619	[5]	9,642	[6]
Significant Other Observable Inputs (Level 2)
Assets:
Total fair value of assets		203,608		125,972
Significant Other Observable Inputs (Level 2) | Commercial Paper | Short-Term Investments
Assets:
Total fair value of assets		101,161	[3]	88,414	[4]
Significant Other Observable Inputs (Level 2) | US Government Agency Securities | Short-Term Investments
Assets:
Total fair value of assets		40,633	[3]	26,824	[4]
Significant Other Observable Inputs (Level 2) | US Government Agency Securities | Long-Term Investments
Assets:
Total fair value of assets	[5]	22,217
Significant Other Observable Inputs (Level 2) | Corporate Debt Securities | Short-Term Investments
Assets:
Total fair value of assets		$ 39,597	[3]	$ 10,734	[4]
[1] Included as cash and cash equivalents on the condensed consolidated balance sheets. Included as cash and cash equivalents on the condensed consolidated balance sheets. Included as short-term marketable securities on the condensed consolidated balance sheets. Included as short-term marketable securities on the condensed consolidated balance sheets. Included as long-term marketable securities on the condensed consolidated balance sheets. Included as long-term marketable securities on the condensed consolidated balance sheets.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended
	Jul. 31, 2024	Jun. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Impairment adjustment to equity investment			$ 402,000
New investment obligation in equity securities			235,000
Measurement at fair value, transfers among Level 1, Level 2 or Level 3			0	$ 0
Subsequent Event
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Payment for investment obligation	$ 157,000
Affini T Therapeutics, Inc.
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investment in equity securities		$ 1,800,000	$ 1,800,000	$ 2,000,000
Impairment adjustment to equity investment		$ 402,000

Marketable Securities - Summary

Marketable Securities - Summary of Marketable Securities Accounted for Available-for-Sale-Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 287,642	$ 228,840
Available for sale securities, Unrealized gains	25	239
Available for sale securities, Unrealized losses	(221)	(162)
Available for sale securities, Estimated fair value	287,446	228,917
US Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	54,294	93,377
Available for sale securities, Unrealized gains		74
Available for sale securities, Unrealized losses	(75)	(148)
Available for sale securities, Estimated fair value	$ 54,219	$ 93,303
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	$ 40,655	$ 26,783
Available for sale securities, Unrealized gains		45
Available for sale securities, Unrealized losses	(22)	(4)
Available for sale securities, Estimated fair value	$ 40,633	$ 26,824
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	$ 39,656	$ 10,719
Available for sale securities, Unrealized gains		15
Available for sale securities, Unrealized losses	(59)
Available for sale securities, Estimated fair value	$ 39,597	$ 10,734
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	$ 101,213	$ 88,356
Available for sale securities, Unrealized gains	5	68
Available for sale securities, Unrealized losses	(57)	(10)
Available for sale securities, Estimated fair value	$ 101,161	$ 88,414
Commercial Paper | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year	1 year
US Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 29,611	$ 9,605
Available for sale securities, Unrealized gains	15	37
Available for sale securities, Unrealized losses	(7)
Available for sale securities, Estimated fair value	$ 29,619	$ 9,642
US Treasury Securities | Minimum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year	1 year
US Treasury Securities | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity	2 years	2 years
US Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 22,213
Available for sale securities, Unrealized gains	5
Available for sale securities, Unrealized losses	(1)
Available for sale securities, Estimated fair value	$ 22,217
US Government Agency Securities | Minimum
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year
US Government Agency 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	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	$ 208,384	$ 105,554
Unrealized losses less than 12 months, Unrealized losses	(164)	(162)
Unrealized losses 12 months or greater, Fair value	22,280
Unrealized losses 12 months or greater, Unrealized losses	(57)
Fair value, Total	230,664	105,554
Unrealized losses, Total	(221)	(162)
US Treasury Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	49,730	74,912
Unrealized losses less than 12 months, Unrealized losses	(25)	(148)
Unrealized losses 12 months or greater, Fair value	22,280
Unrealized losses 12 months or greater, Unrealized losses	(57)
Fair value, Total	72,010	74,912
Unrealized losses, Total	(82)	(148)
US Government Agency Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	45,875	6,950
Unrealized losses less than 12 months, Unrealized losses	(23)	(4)
Fair value, Total	45,875	6,950
Unrealized losses, Total	(23)	(4)
Corporate Debt Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	39,597	748
Unrealized losses less than 12 months, Unrealized losses	(59)
Fair value, Total	39,597	748
Unrealized losses, Total	(59)
Commercial Paper
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	73,182	22,944
Unrealized losses less than 12 months, Unrealized losses	(57)	(10)
Fair value, Total	73,182	22,944
Unrealized losses, Total	$ (57)	$ (10)

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) $ in Thousands	Jun. 30, 2024 USD ($) Position	Dec. 31, 2023 USD ($) Position
Investments, Debt and Equity Securities [Abstract]
Available of sale securities, unrealized loss position, Number of positions | Position	40	22
Available for sale securities, gross unrealized loss position	$ 230,664	$ 105,554
Available of sale securities, unrealized loss position, greater than 12 months, Number of positions | Position	4	0
Available of sale securities, unrealized loss position, greater than 12 months	$ 22,280
Available-for-sale securities, accrued interest	$ 2,200	$ 1,100
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Current, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets	Prepaid expenses and other current assets

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Property and equipment	$ 26,338	$ 29,559
Less accumulated depreciation and amortization	(8,348)	(7,232)
Property and equipment, net	17,990	22,327
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment	4,745	5,620
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment	3,712	4,099
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	16,313	18,173
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	$ 1,568	$ 1,667

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 1,100,000	$ 955,000	$ 2,131,000	$ 1,849,000

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 11,044	$ 8,803
Accrued compensation	6,148	10,311
Unvested early exercised stock option liability	155	464
Accrued professional services	526	435
Accrued property and equipment		13
Accrued offering and deferred offering costs	196
Other accruals	396	160
Total	$ 18,465	$ 20,186

Asset Acquisitions - Additional

Asset Acquisitions - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Asset Acquisition [Line Items]
In-process research and development		$ 22,500,000		$ 22,500,000
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	0	$ 0
Milestones accrued		$ 0		$ 0		$ 0
Asana Merger Agreement | Series B-2 Convertible Preferred Stock
Asset Acquisition [Line Items]
Shares issued	4,000,000
Value per share	$ 7.5
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

License Agreements - Additional

License Agreements - Additional Information (Details) - USD ($)	1 Months Ended							3 Months Ended		6 Months Ended
	May 31, 2024	Dec. 31, 2022	Mar. 31, 2022	Jan. 31, 2021	Apr. 30, 2020	Mar. 31, 2020	Feb. 29, 2020	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
License Agreements [Line Items]
In-process research and development								$ 22,500,000		$ 22,500,000
License Agreement | Novartis Pharma AG
License Agreements [Line Items]
Upfront payment		$ 20,000,000
In-process research and development								0	$ 0	0	$ 0
Stock issued, value		$ 80,000,000
Stock issued and sold		12,307,692
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	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	$ 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
Joyo License Agreement | Guangzhou Joyo Pharmatech Co., Ltd.
License Agreements [Line Items]
Upfront payment	$ 12,500,000
In-process research and development								12,500,000		12,500,000
Joyo License Agreement | Guangzhou Joyo Pharmatech Co., Ltd. | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation	51,500,000
Development and regulatory milestone payments obligation if territory expanded	57,500,000
Commercial milestone payments obligation	125,000,000
Joyo License Agreement | Guangzhou Joyo Pharmatech Co., Ltd. | Phase 2 Clinical Trial
License Agreements [Line Items]
Payment for option to expand territory of license on or prior to first dosing of first patient	50,000,000
Payment for option to expand territory of license after first dosing of first patient	150,000,000
Medshine License Agreement | Medshine Discovery Inc.
License Agreements [Line Items]
Upfront payment	10,000,000
In-process research and development								$ 10,000,000		$ 10,000,000
Medshine License Agreement | Medshine Discovery Inc. | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation	30,000,000
Commercial milestone payments obligation	$ 130,000,000

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended		5 Months Ended	6 Months Ended
	May 21, 2024	Jul. 31, 2021	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2021	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			49,569,803			49,569,803		42,394,435
Share-based compensation, shares subject to repurchase			123,961			123,961		371,876
Stock-based compensation			$ 7,180,000	$ 7,012,000		$ 14,028,000	$ 13,857,000
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			$ 155,000			$ 155,000		$ 464,000
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			34,828,546			34,828,546		24,970,957
Stock vesting period						4 years
Weighted-average grant date fair value of options granted			$ 1.48	$ 2.05		$ 1.28	$ 2.83
Unrecognized compensation cost related to unvested stock option grants			$ 47,400,000			$ 47,400,000
Unrecognized compensation cost expected to be recognized as expense, period						2 years 8 months 1 day
Intrinsic value of options exercised			$ 123,000	$ 376,000		$ 170,000	$ 893,000
Share-based compensation, options granted that vest based on performance milestone						11,596,445
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
Option Repricing | Black-Scholes Option Pricing Model
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment arrangement, incremental cost	$ 1,100,000
Option Repricing | Straight-line Basis Through Premium End Date
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment arrangement, incremental cost	559,000
Option Repricing | Straight-line Basis Over Greater of Period Through Premium End Date
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment arrangement, incremental cost	$ 558,000
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			12,913,020			12,913,020
Shares of common stock, authorized for issuance		15,150,000
Percentage of outstanding common stock maximum		5%
2021 Incentive Award Plan | Option Repricing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, options repriced	7,478,918
Decrease in stock option, exercise price	$ 2.35
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			$ 1,000,000			$ 1,000,000
Unrecognized compensation cost expected to be recognized as expense, period						1 year 5 months 19 days
Stock-based compensation			103,000	$ 349,000		$ 444,000	$ 1,100,000
Share-based payment arrangement, withheld on behalf of employees for future purchase			$ 43,000			$ 43,000		$ 46,000
Offering period		24 months
Purchase period		6 months
Shares issued under ESPP			252,444	223,696		252,444	223,696
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 $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Outstanding at December 31, 2023 | shares	24,970,957
Shares Granted | shares	11,596,445
Shares Exercised | shares	(145,293)
Shares Canceled | shares	(1,593,563)
Shares Outstanding at June 30, 2024 | shares	34,828,546	24,970,957
Shares Options exercisable at June 30, 2024 | shares	15,155,782
Weighted-average exercise price, Outstanding at December 31, 2023 | $ / shares	$ 4.98
Weighted-average exercise price, Granted | $ / shares	1.76
Weighted-average exercise price, Exercised | $ / shares	0.89
Weighted-average exercise price, Canceled | $ / shares	3.93
Weighted-average exercise price, Outstanding at June 30, 2024 | $ / shares	3.97	$ 4.98
Weighted-average exercise price, Options exercisable at June 30, 2024 | $ / shares	$ 4.7
Weighted-average remaining contractual term (years), Outstanding	8 years 18 days	8 years 1 month 13 days
Weighted-average remaining contractual term (years), Options exercisable at June 30, 2024	6 years 9 months 29 days
Aggregate intrinsic value, Outstanding | $	$ 11,579	$ 4,412
Aggregate intrinsic value, Options exercisable at June 30, 2024 | $	$ 5,433

Stock-based Compensation - Assu

Stock-based Compensation - Assumptions used to Determine Fair Value of Stock Option Grants (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate, minimum	4.26%	3.50%	3.84%	3.46%
Risk-free interest rate, maximum	4.64%	3.98%	4.64%	4.22%
Expected volatility, minimum	82.72%	83.20%	82.72%	83.20%
Expected volatility, maximum	83.14%	85.02%	83.91%	85.81%
Expected dividend yield	0%	0%	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	5 years 3 months 10 days	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	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	4.75%	4.70%	4.75%	4.70%
Risk-free interest rate, maximum	5.39%	5.35%	5.39%	5.35%
Expected volatility, minimum	68.73%	72.54%	68.73%	72.54%
Expected volatility, maximum	74.72%	82.79%	74.72%	82.79%
Expected dividend yield	0%	0%	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	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	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	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 7,180	$ 7,012	$ 14,028	$ 13,857
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	3,788	3,867	7,272	7,747
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 3,392	$ 3,145	$ 6,756	$ 6,110

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Jun. 30, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	49,569,803	42,394,435
Stock Options Issued and Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	34,828,546	24,970,957
Awards Available for Future Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	12,913,020	15,342,797
Shares Available for Purchase Under ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,828,237	2,080,681

Leases - Additional Information

Leases - Additional Information (Details)		1 Months Ended				3 Months Ended		6 Months Ended
	Jan. 31, 2024 ft²	Apr. 30, 2022	Dec. 31, 2021 USD ($) ft²	Mar. 31, 2021 ft²	Sep. 30, 2020 USD ($) ft²	Jun. 30, 2024 USD ($) ft²	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) ft²	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Lessee Lease Description [Line Items]
Operating leases cancellable and non-cancellable expiration dates								2032
Operating leases Noncancelable expiration dates								2026
Total lease cost						$ 3,200,000	$ 2,800,000	$ 5,900,000	$ 5,800,000
Operating lease cost						2,400,000	1,900,000	4,300,000	3,800,000
Variable lease costs						918,000	$ 859,000	1,800,000	2,000,000
Cash paid for operating leases								4,100,000	$ 2,600,000
Sublease income						$ 132,000		$ 216,000
Operating lease, weighted-average remaining lease term						7 years 9 months 21 days		7 years 9 months 21 days		8 years 3 months 14 days
Operating lease, weighted-average discount rate						8.96%		8.96%		8.95%
Operating lease, aggregate monthly payments to lessor						$ 76,194,000		$ 76,194,000
Letter of credit provided to lessor						408,000		408,000		$ 408,000
Noncash impairment charge								$ 4,653,000
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		$ 5,100,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]						Operating Lease, Right-of-Use Asset		Operating Lease, Right-of-Use Asset
2021 Lease | Other Assets
Lessee Lease Description [Line Items]
Security deposit paid			$ 874,000
2024 Lease
Lessee Lease Description [Line Items]
Sublease income						$ 132,000		$ 216,000
Office space leases | ft²	10,000					18,421		18,421
Lessor, Operating lease initial term	3 years					61 months		61 months
Lessor, Operating lease existence of option to extend [true false]	true
Lessor, Operating lease existence of option to terminate [true false]	true
Lease discount rate						13.50%		13.50%
Noncash impairment charge						$ 4,700,000		$ 4,700,000
Operating lease assets impairment						2,400,000		2,400,000
Leasehold improvements and furniture impairment						2,300,000		2,300,000
2024 Lease | Research and Development Expense
Lessee Lease Description [Line Items]
Noncash impairment charge						3,000,000		3,000,000
2024 Lease | General and Administrative Expense
Lessee Lease Description [Line Items]
Noncash impairment charge						$ 1,700,000		$ 1,700,000

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments under Operating Leases (Details) $ in Thousands	Jun. 30, 2024 USD ($)
Leases [Abstract]
2024 (remaining six months)	$ 4,426
2025	9,024
2026	9,170
2027	9,199
2028	9,277
Thereafter	35,098
Total lease payments	76,194
Less: Amount representing interest	(22,226)
Operating lease liabilities	$ 53,968

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Charges in connection with reduction in force	$ 2.2	$ 2.2

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Provision for federal income taxes	$ 0	$ 0	$ 0	$ 0
Provision for state income taxes	0	0	0	0
Provision for foreign income taxes	0	0	0	0
Interest or penalties related to income taxes	$ 0	$ 0	$ 0	$ 0

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	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net Income (Loss)	$ (63,201)	$ (35,017)	$ (31,781)	$ (33,199)	$ (98,218)	$ (64,980)
Weighted-average shares of common stock used in computing net loss per share, basic	217,806,567		150,037,029		184,484,154	149,772,093
Weighted-average shares of common stock used in computing net loss per share, diluted	217,806,567		150,037,029		184,484,154	149,772,093
Net loss per share, basic	$ (0.29)		$ (0.21)		$ (0.53)	$ (0.43)
Net loss per share, diluted	$ (0.29)		$ (0.21)		$ (0.53)	$ (0.43)

Net Loss Per Share - Anti-dilut

Net Loss Per Share - Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	35,750,745	27,529,275
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	34,828,546	25,519,872
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	123,961	658,857
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	798,238	1,350,546

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended
	Apr. 30, 2023	Jun. 30, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Prepaid expenses and other current assets		$ 9,593,000	$ 8,326,000
Affini T Therapeutics, Inc.
Related Party Transaction [Line Items]
Investment in equity securities		$ 1,800,000	$ 2,000,000
Erasca Foundation
Related Party Transaction [Line Items]
Amount loaned in exchange of non-interest bearing promissory note	$ 125,000
Amount donated to related party	$ 125,000

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	6 Months Ended
	Aug. 31, 2022	Aug. 12, 2024	Jun. 30, 2024
Subsequent Event [Line Items]
Net proceeds from offering			$ 174,638
July 2024 ATM Offering | Common Stock | Maximum | Jefferies LLC
Subsequent Event [Line Items]
Aggregate offering price	$ 200,000
Percentage of commission on gross sales proceeds	3%
July 2024 ATM Offering | Common Stock | Subsequent Event
Subsequent Event [Line Items]
Net proceeds from offering		$ 21,100
Offering costs		$ 800
July 2024 ATM Offering | Common Stock | Subsequent Event | Jefferies LLC
Subsequent Event [Line Items]
Number of stock sold		9,231,114
Weighted average price per share		$ 2.37