Erasca (ERAS) 10-Q 8 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 02, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
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		173,358,966
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 ($)	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 76,726,000	$ 93,075,000
Short-term marketable securities	220,959,000	219,275,000
Prepaid expenses and other current assets	8,938,000	8,326,000
Total current assets	306,623,000	320,676,000
Long-term marketable securities		9,642,000
Property and equipment, net	21,358,000	22,327,000
Operating lease assets	37,177,000	37,861,000
Restricted cash	408,000	408,000
Other assets	4,456,000	4,383,000
Total assets	370,022,000	395,297,000
Current liabilities:
Accounts payable	2,633,000	2,000,000
Accrued expenses and other current liabilities	16,577,000	20,186,000
Proceeds from prepayment of private placement	6,907,000
Operating lease liabilities	4,126,000	3,970,000
Total current liabilities	30,243,000	26,156,000
Operating lease liabilities, net of current portion	50,811,000	51,889,000
Other liabilities	559,000	566,000
Total liabilities	81,613,000	78,611,000
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock, $0.0001 par value; 80,000,000 shares authorized at March 31, 2024 and December 31, 2023; no shares issued and outstanding at March 31, 2024 and December 31, 2023
Common stock, $0.0001 par value; 800,000,000 shares authorized at March 31, 2024 and December 31, 2023; 151,497,138 and 151,462,103 shares issued at March 31, 2024 and December 31, 2023, respectively; 151,249,219 and 151,090,227 shares outstanding at March 31, 2024 and December 31, 2023, respectively	15,000	15,000
Additional paid-in capital	929,634,000	922,607,000
Accumulated other comprehensive (loss) income	(210,000)	77,000
Accumulated deficit	(641,030,000)	(606,013,000)
Total stockholders' equity	288,409,000	316,686,000
Total liabilities and stockholders' equity	$ 370,022,000	$ 395,297,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 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	151,497,138	151,462,103
Common stock, shares outstanding	151,249,219	151,090,227

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 28,574	$ 27,585
General and administrative	10,277	9,440
Total operating expenses	38,851	37,025
Loss from operations	(38,851)	(37,025)
Other income (expense)
Interest income	3,900	3,877
Other expense, net	(66)	(51)
Total other income (expense), net	3,834	3,826
Net loss	$ (35,017)	$ (33,199)
Net loss per share, basic	$ (0.23)	$ (0.22)
Net loss per share, diluted	$ (0.23)	$ (0.22)
Weighted-average shares of common stock used in computing net loss per share, basic	151,161,741	149,504,216
Weighted-average shares of common stock used in computing net loss per share, diluted	151,161,741	149,504,216
Other comprehensive income (loss):
Unrealized (loss) gain on marketable securities, net	$ (287)	$ 527
Comprehensive loss	$ (35,304)	$ (32,672)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	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 Income (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, 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 Income (Loss)	(35,017)				(35,017)
Unrealized gain (loss) on marketable securities, net	$ (287)			(287)
Ending balance, shares at Mar. 31, 2024	151,497,138	151,497,138
Ending balance at Mar. 31, 2024	$ 288,409	$ 15	$ 929,634	$ (210)	$ (641,030)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (35,017,000)	$ (33,199,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	998,000	894,000
Stock-based compensation expense	6,848,000	6,845,000
Accretion on marketable securities, net	(2,342,000)	(975,000)
Changes in operating assets and liabilities:
Prepaid expenses and other current and long-term assets	(507,000)	670,000
Accounts payable	633,000	446,000
Accrued expenses and other current and long-term liabilities	(3,626,000)	(4,363,000)
Operating lease assets and liabilities, net	(238,000)	3,324,000
Net cash used in operating activities	(33,251,000)	(26,358,000)
Cash flows from investing activities:
Purchases of marketable securities	(43,987,000)	(24,280,000)
Maturities of marketable securities	54,000,000	60,200,000
In-process research and development		(20,000,000)
Purchases of property and equipment	(42,000)	(1,206,000)
Net cash provided by investing activities	9,971,000	14,714,000
Cash flows from financing activities:
Proceeds from prepayment of private placement	6,907,000
Proceeds from the exercise of stock options	24,000	183,000
Net cash provided by financing activities	6,931,000	183,000
Net decrease in cash, cash equivalents and restricted cash	(16,349,000)	(11,461,000)
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	77,134,000	273,164,000
Supplemental disclosure of noncash investing and financing activities:
Amounts accrued for purchases of property and equipment		38,000
Amounts accrued for offering costs	178,000
Vesting of early exercised options	$ 155,000	$ 243,000

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (35,017)	$ (33,199)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On January 10, 2024 , David M. Chacko , M.D., our Chief Financial Officer and Chief Business Officer , 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 260,000 shares of our common stock until December 31, 2025 .
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
David M. Chacko [Member]
Trading Arrangements, by Individual
Name	David M. Chacko
Title	M.D., our Chief Financial Officer and Chief Business Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	January 10, 2024
Termination Date	December 31, 2025
Arrangement Duration	722 days
Aggregate Available	260,000

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 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 March 31, 2024, the Company had $ 297.7 million in cash, cash equivalents, and short-term marketable securities. As of March 31, 2024, the Company had an accumulated deficit of $ 641.0 million. The Company has incurred significant operating losses and negative cash flows from operations. From its inception through March 31, 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) and underwritten offering (2022 Offering). The Company expects to use its cash, cash equivalents, and short-term 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 short-term marketable securities as of March 31, 2024, plus the net proceeds received in April 2024 from the Company's private placement, which closed on April 2, 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 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 (the 2024 Private Placement). On April 2, 2024, the 2024 Private Placement closed and the net proceeds were $ 43.7 million, after deducting placement agent fees and estimated expenses of approximately $ 1.3 m illion. The Company received $ 6.9 million of the proceeds in March 2024 prior to the closing of the 2024 Private Placement, which is recorded in cash and cash equivalents and as a liability in proceeds from prepayment of private placement on the condensed consolidated balance sheets. 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	3 Months Ended
	Mar. 31, 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, 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 March 31, 2024, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2024 and 2023 and the condensed consolidated statements of cash flows for the three months ended March 31, 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 March 31, 2024 and the condensed consolidated results of its operations and cash flows for the three months ended March 31, 2024 and 2023. The condensed consolidated financial data and other information disclosed in these notes related to the three months ended March 31, 2024 and 2023 are unaudited. The condensed consolidated results for the three months ended March 31, 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, money market funds and commercial paper. 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 March 31, 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): March 31, 2024 2023 Cash and cash equivalents $ 76,726 $ 272,756 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 77,134 $ 273,164 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	3 Months Ended
	Mar. 31, 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 March 31, 2024 using Quoted prices in Significant Significant active markets other unobservable March 31, for identical observable inputs 2024 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 58,324 $ 58,324 $ — $ — Commercial paper (1) 1,492 — 1,492 — US treasury securities (2) 73,644 73,644 — — US government agency securities (2) 23,856 — 23,856 — Corporate debt securities (2) 22,926 — 22,926 — Commercial paper (2) 100,533 — 100,533 — Total fair value of assets $ 280,775 $ 131,968 $ 148,807 $ — (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. 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, accrued expenses and other current liabilities and proceeds from prepayment of private placement, approximate fair value due to their short maturities. As of March 31, 2024 and December 31, 2023 , the Company held a $ 2.0 million equity investment in Affini-T Therapeutics, Inc. (Affini-T) at cost. No adjustments have been made to the value of the Company’s investment in Affini-T since its initial measurement either due to impairment or based on observable price changes. None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented. Cash equivalents consist of money market funds and commercial paper, 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. 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	3 Months Ended
	Mar. 31, 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): March 31, 2024 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 73,753 $ 8 $ ( 117 ) $ 73,644 US government agency securities 1 or less 23,859 11 ( 14 ) 23,856 Corporate debt securities 1 or less 22,967 — ( 41 ) 22,926 Commercial paper 1 or less 100,590 16 ( 73 ) 100,533 Total $ 221,169 $ 35 $ ( 245 ) $ 220,959 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 March 31, 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): March 31, 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 $ 55,139 $ ( 117 ) $ — $ — $ 55,139 $ ( 117 ) US government agency securities 18,845 ( 14 ) — — 18,845 ( 14 ) Corporate debt securities 22,926 ( 41 ) — — 22,926 ( 41 ) Commercial paper 65,574 ( 73 ) — — 65,574 ( 73 ) Total $ 162,484 $ ( 245 ) $ — $ — $ 162,484 $ ( 245 ) 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 March 31, 2024, there were 28 available-for-sale securities with an estimated fair value of $ 162.5 million in gross unrealized loss positions, none of which 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 March 31, 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 interest rate increases. Additionally, the Company does not intend to sell the securities nor is it more likely than not that the Company will be required to sell the securities before recovery of their amortized cost basis. Accrued interest on the Company’s available-for-sale securities was $ 871,000 and $ 1.1 million as of March 31, 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	3 Months Ended
	Mar. 31, 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): March 31, December 31, 2024 2023 Laboratory equipment $ 5,621 $ 5,620 Furniture and fixtures 4,099 4,099 Leasehold improvements 18,173 18,173 Computer equipment and software 1,695 1,667 Property and equipment 29,588 29,559 Less accumulated depreciation and amortization ( 8,230 ) ( 7,232 ) Property and equipment, net $ 21,358 $ 22,327 Depreciation and amortization expense related to property and equipment was $ 998,000 and $ 894,000 for the three months ended March 31, 2024 and 2023 , respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 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): March 31, December 31, 2024 2023 Accrued research and development expenses $ 9,247 $ 8,803 Accrued compensation 6,095 10,311 Unvested early exercised stock option liability 309 464 Accrued professional services 626 435 Accrued offering costs 178 — Accrued property and equipment — 13 Other accruals 122 160 Total $ 16,577 $ 20,186

Asset Acquisitions

Asset Acquisitions	3 Months Ended
	Mar. 31, 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 months ended March 31, 2024 and 2023. As of March 31, 2024 and December 31, 2023 , no milestones had been accrued as the underlying contingencies were not probable or estimable. Emerge Life Sciences, Pte. Ltd. In March 2021, the Company entered into an asset purchase agreement (ELS Purchase Agreement) with Emerge Life Sciences, Pte. Ltd. (ELS) wherein it purchased all rights, title, and interest (including all patent and other intellectual property rights) to EGFR antibodies directed against the EGFR domain II (EGFR-D2) and domain III (EGFR-D3) as well as a bispecific antibody where one arm is directed against EGFR-D2 and the other is directed against EGFR-D3 (the Antibodies). Under the terms of the ELS Purchase Agreement, in 2021, the Company made an upfront payment of $ 2.0 million and issued to ELS 500,000 shares of the Company’s common stock at a value of $ 3.36 per share or a total fair value of equity of $ 1.7 million. No IPR&D expense was recorded during the three months ended March 31, 2024 and 2023 .

License Agreements

License Agreements	3 Months Ended
	Mar. 31, 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 months ended March 31, 2024 and 2023. As of March 31, 2024 and December 31, 2023 , no milestones are accrued as the underlying contingencies are not probable or estimable. Katmai Pharmaceuticals, Inc. In March 2020, the Company entered into a license agreement (the Katmai Agreement) with Katmai Pharmaceuticals, Inc. (Katmai) under which the Company was granted an exclusive, worldwide, royalty-bearing license to certain patent rights and know-how controlled by Katmai related to the development of small molecule therapeutic and diagnostic products that modulate EGFR and enable the identification, diagnosis, selection, treatment, and/or monitoring of patients for neuro-oncological applications to develop, manufacture, use, and commercialize ERAS-801 and certain other related compounds in all fields of use. Under the Katmai Agreement, the Company made an upfront payment of $ 5.7 million and Katmai agreed to purchase shares of the Company’s Series B-1 convertible preferred stock and Series B-2 convertible preferred stock having an aggregate value of $ 2.7 million. In April 2020, Katmai purchased 356,000 shares of the Company’s Series B-1 convertible preferred stock for $ 1.8 million, and in January 2021, Katmai purchased 118,666 shares of the Company’s Series B-2 convertible preferred stock for $ 0.9 million. In connection with the Company's IPO, these shares of Series B-1 convertible preferred stock and Series B-2 convertible preferred stock were converted into 395,555 shares of the Company's common stock, in the aggregate. The Company is obligated to make future development and regulatory milestone payments of up to $ 26.0 million, of which $ 2.0 million was paid in March 2022, and commercial milestone payments of up to $ 101.0 million. The Company is also obligated to pay tiered royalties on net sales of each licensed product, at rates ranging from the mid- to high-single digit percentages, subject to a minimum annual royalty payment in the low six figures and certain permitted deductions. No IPR&D expense was recorded during the three months ended March 31, 2024 and 2023. As of March 31, 2024 and December 31, 2023 , no milestones are accrued as the underlying contingencies are not probable or estimable. NiKang Therapeutics, Inc. In February 2020, the Company entered into a license agreement (the NiKang Agreement) with NiKang Therapeutics, Inc. (NiKang) under which the Company was granted an exclusive, worldwide license to certain intellectual property rights owned or controlled by NiKang related to certain SHP2 inhibitors to develop and commercialize ERAS-601 and certain other related compounds for all applications. Under the NiKang Agreement, in 2020, the Company made an upfront payment of $ 5.0 million to NiKang and reimbursed NiKang $ 0.4 million for certain initial manufacturing costs. In addition, the Company paid $ 7.0 million in 2020 related to the publication of a US patent application that covered the composition of matter of ERAS-601. The Company is also obligated to pay (i) development and regulatory milestone payments in an aggregate amount of up to $ 16.0 million for the first licensed product, of which $ 4.0 million was paid in January 2021, and $ 12.0 million for a second licensed product, and (ii) commercial milestone payments in an aggregate amount of up to $ 157.0 million for the first licensed product and $ 151.0 million for a second licensed product. The Company is also obligated to: (i) pay tiered royalties on net sales of all licensed products in the mid-single digit percentages, subject to certain reductions; and (ii) equally split all net sublicensing revenues earned under sublicense agreements that the Company enters into with any third party before commencement of the first Phase I clinical trial for a licensed product. No IPR&D expense was recorded during the three months ended March 31, 2024 and 2023. As of March 31, 2024 and December 31, 2023 , no milestones are accrued as the underlying contingencies are not probable or estimable. LifeArc In April 2020, the Company entered into a license agreement with LifeArc (the LifeArc Agreement) under which the Company was granted an exclusive, worldwide license to certain materials, know-how, and intellectual property rights owned or controlled by LifeArc to develop, manufacture, use, and commercialize certain ULK inhibitors for all applications. Under the LifeArc Agreement, the Company was granted the license at no upfront cost and a period of three months after the effective date to conduct experiments on LifeArc’s compounds. Upon completion of this initial testing period, the Company had the option to continue the license and make a one-time license payment of $ 75,000 to LifeArc, which payment was subsequently made in 2020. The Company is obligated to make future development milestone payments for a licensed product of up to $ 11.0 million and sales milestone payments of up to $ 50.0 million. The Company is also obligated to pay royalties on net sales of all licensed products, in the low-single digit percentages, subject to certain reductions. No IPR&D expense was recorded during the three months ended March 31, 2024 and 2023. As of March 31, 2024 and December 31, 2023 , no milestones are accrued as the underlying contingencies are not probable or estimable.

Stock-based Compensation

Stock-based Compensation	3 Months Ended
	Mar. 31, 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 March 31, 2024, there were 13,204,701 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 9,827,650 1.71 Exercised ( 35,035 ) 0.69 Canceled ( 116,449 ) 4.89 Outstanding at March 31, 2024 34,647,123 $ 4.06 8.44 $ 7,532 Options exercisable at March 31, 2024 12,850,952 $ 4.83 7.32 $ 3,916 The weighted-average grant date fair value of options granted for the three months ended March 31, 2024 and 2023 was $ 1.25 and $ 2.94 , respectively. As of March 31, 2024, the unrecognized compensation cost related to unvested stock option grants was $ 55.9 million and is expected to be recognized as expense over approximately 2.75 years. The intrinsic value of the options exercised for the three months ended March 31, 2024 and 2023 was $ 47,000 and $ 517,000 , 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 March 31, 2024 and December 31, 2023, there were 247,919 shares and 371,876 shares subject to repurchase by the Company, respectively. As of March 31, 2024 and December 31, 2023, the Company recorded $ 309,000 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 March 31, 2024 2023 Risk-free interest rate 3.84 %- 4.15 % 3.46 %- 4.22 % Expected volatility 83.35 %- 83.91 % 85.52 %- 85.81 % Expected term (in years) 5.28 - 6.01 6.02 - 6.07 Expected dividend yield -- % -- % 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 $ 342,000 and $ 707,000 during the three months ended March 31, 2024 and 2023, respectively. As of March 31, 2024, the unrecognized compensation cost related to the ESPP was $ 1.5 million and is expected to be recognized as expense over approximately 1.69 years. As of March 31, 2024 and December 31, 2023, $ 317,000 and $ 46,000 h as 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. No shares were issued and sold under the ESPP during the three months ended March 31, 2024 and 2023. Stock-based compensation expense The allocation of stock-based compensation for all stock awards was as follows (in thousands): Three Months Ended March 31, 2024 2023 Research and development $ 3,484 $ 3,880 General and administrative 3,364 2,965 Total $ 6,848 $ 6,845 Common stock reserved for future issuance Common stock reserved for future issuance consisted of the following as of March 31, 2024 and December 31, 2023: March 31, December 31, 2024 2023 Stock options issued and outstanding 34,647,123 24,970,957 Awards available for future grant 13,204,701 15,342,797 Shares available for purchase under the ESPP 2,080,681 2,080,681 Total 49,932,505 42,394,435

Leases

Leases	3 Months Ended
	Mar. 31, 2024
Leases [Abstract]
Leases	Note 10. Leases Operating leases The Company has facility leases for office space under non-cancellable and cancelable operating leases with various expiration dates through 2032 and equipment under a non-cancellable operating lease with a term expiring in 2026 . Total lease costs were approximately $ 2.7 million and $ 3.1 million, including operating lease costs of $ 1.9 million and $ 1.9 million, variable lease costs of $ 916,000 and $ 1.2 million, and sublease income of $ 84,000 and $ 0, durin g the three months ended March 31, 2024 and 2023, respectively. The Company paid $ 2.1 million and $ 863,000 in cash for operating leases, net of sublease income, that were included in the operating activities section of the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023, respectively. The weighted-average remaining lease term and the weighted-average discount rate of the Company’s operating leases were 8.05 years and 8.96 %, respectively, at March 31, 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 will recognize 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 $ 84,000 related to income from this sublease during the three months ended March 31, 2024. Future minimum lease payments under the operating leases with initial lease terms in excess of one year as of March 31, 2024 are as follows (in thousands): Year ending December 31, 2024 (remaining nine months) $ 6,602 2025 9,024 2026 9,170 2027 9,199 2028 9,277 Thereafter 35,098 Total lease payments $ 78,370 Less: Amount representing interest ( 23,433 ) Operating lease liabilities $ 54,937

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 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.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 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 months ended March 31, 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 months ended March 31, 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	3 Months Ended
	Mar. 31, 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 March 31, 2024 2023 Net loss $ ( 35,017 ) $ ( 33,199 ) Weighted-average shares of common stock used in computing net loss per share, basic and diluted 151,161,741 149,504,216 Net loss per share, basic and diluted $ ( 0.23 ) $ ( 0.22 ) 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: March 31, March 31, 2024 2023 Options to purchase common stock 34,647,123 25,892,271 Options early exercised subject to future vesting 247,919 948,179 Estimated shares purchasable under the ESPP 1,301,205 755,809 Total potentially dilutive shares 36,196,247 27,596,259

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 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 2024, the Company donated $ 125,000 to the Erasca Foundation. Affini-T Therapeutics, Inc. The Company holds a $ 2.0 million equity investment in Affini-T. One of the Company’s board members is also a member of the board of Affini-T.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2024
Subsequent Events [Abstract]
Subsequent Event	Note 15. Subsequent event On April 2, 2024, the Company completed the 2024 Private Placement in which the Company issued and sold 21,844,660 shares of common stock at a price of $ 2.06 per share. Net proceeds from the 2024 Private Placement, after deducting placement agent fees and estimated expenses, were $ 43.7 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 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, 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 March 31, 2024, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2024 and 2023 and the condensed consolidated statements of cash flows for the three months ended March 31, 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 March 31, 2024 and the condensed consolidated results of its operations and cash flows for the three months ended March 31, 2024 and 2023. The condensed consolidated financial data and other information disclosed in these notes related to the three months ended March 31, 2024 and 2023 are unaudited. The condensed consolidated results for the three months ended March 31, 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, money market funds and commercial paper. 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 March 31, 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): March 31, 2024 2023 Cash and cash equivalents $ 76,726 $ 272,756 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 77,134 $ 273,164
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)	3 Months Ended
	Mar. 31, 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): March 31, 2024 2023 Cash and cash equivalents $ 76,726 $ 272,756 Restricted cash 408 408 Total cash, cash equivalents and restricted cash $ 77,134 $ 273,164

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2024 using Quoted prices in Significant Significant active markets other unobservable March 31, for identical observable inputs 2024 assets (level 1) inputs (level 2) (level 3) Assets: Money market funds (1) $ 58,324 $ 58,324 $ — $ — Commercial paper (1) 1,492 — 1,492 — US treasury securities (2) 73,644 73,644 — — US government agency securities (2) 23,856 — 23,856 — Corporate debt securities (2) 22,926 — 22,926 — Commercial paper (2) 100,533 — 100,533 — Total fair value of assets $ 280,775 $ 131,968 $ 148,807 $ — (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. 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)	3 Months Ended
	Mar. 31, 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): March 31, 2024 Maturity Amortized Unrealized Unrealized Estimated (in years) cost gains losses fair value US treasury securities 1 or less $ 73,753 $ 8 $ ( 117 ) $ 73,644 US government agency securities 1 or less 23,859 11 ( 14 ) 23,856 Corporate debt securities 1 or less 22,967 — ( 41 ) 22,926 Commercial paper 1 or less 100,590 16 ( 73 ) 100,533 Total $ 221,169 $ 35 $ ( 245 ) $ 220,959 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 March 31, 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): March 31, 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 $ 55,139 $ ( 117 ) $ — $ — $ 55,139 $ ( 117 ) US government agency securities 18,845 ( 14 ) — — 18,845 ( 14 ) Corporate debt securities 22,926 ( 41 ) — — 22,926 ( 41 ) Commercial paper 65,574 ( 73 ) — — 65,574 ( 73 ) Total $ 162,484 $ ( 245 ) $ — $ — $ 162,484 $ ( 245 ) 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)	3 Months Ended
	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): March 31, December 31, 2024 2023 Laboratory equipment $ 5,621 $ 5,620 Furniture and fixtures 4,099 4,099 Leasehold improvements 18,173 18,173 Computer equipment and software 1,695 1,667 Property and equipment 29,588 29,559 Less accumulated depreciation and amortization ( 8,230 ) ( 7,232 ) Property and equipment, net $ 21,358 $ 22,327

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 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): March 31, December 31, 2024 2023 Accrued research and development expenses $ 9,247 $ 8,803 Accrued compensation 6,095 10,311 Unvested early exercised stock option liability 309 464 Accrued professional services 626 435 Accrued offering costs 178 — Accrued property and equipment — 13 Other accruals 122 160 Total $ 16,577 $ 20,186

Stock-based Compensation (Table

Stock-based Compensation (Tables)	3 Months Ended
	Mar. 31, 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 9,827,650 1.71 Exercised ( 35,035 ) 0.69 Canceled ( 116,449 ) 4.89 Outstanding at March 31, 2024 34,647,123 $ 4.06 8.44 $ 7,532 Options exercisable at March 31, 2024 12,850,952 $ 4.83 7.32 $ 3,916
Schedule of Stock-based Compensation Expense	The allocation of stock-based compensation for all stock awards was as follows (in thousands): Three Months Ended March 31, 2024 2023 Research and development $ 3,484 $ 3,880 General and administrative 3,364 2,965 Total $ 6,848 $ 6,845
Summary of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consisted of the following as of March 31, 2024 and December 31, 2023: March 31, December 31, 2024 2023 Stock options issued and outstanding 34,647,123 24,970,957 Awards available for future grant 13,204,701 15,342,797 Shares available for purchase under the ESPP 2,080,681 2,080,681 Total 49,932,505 42,394,435
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 March 31, 2024 2023 Risk-free interest rate 3.84 %- 4.15 % 3.46 %- 4.22 % Expected volatility 83.35 %- 83.91 % 85.52 %- 85.81 % Expected term (in years) 5.28 - 6.01 6.02 - 6.07 Expected dividend yield -- % -- %

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2024
Leases [Abstract]
Schedule of Future Minimum Lease Payments under Operating Leases	Future minimum lease payments under the operating leases with initial lease terms in excess of one year as of March 31, 2024 are as follows (in thousands): Year ending December 31, 2024 (remaining nine months) $ 6,602 2025 9,024 2026 9,170 2027 9,199 2028 9,277 Thereafter 35,098 Total lease payments $ 78,370 Less: Amount representing interest ( 23,433 ) Operating lease liabilities $ 54,937

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2024 2023 Net loss $ ( 35,017 ) $ ( 33,199 ) Weighted-average shares of common stock used in computing net loss per share, basic and diluted 151,161,741 149,504,216 Net loss per share, basic and diluted $ ( 0.23 ) $ ( 0.22 )
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: March 31, March 31, 2024 2023 Options to purchase common stock 34,647,123 25,892,271 Options early exercised subject to future vesting 247,919 948,179 Estimated shares purchasable under the ESPP 1,301,205 755,809 Total potentially dilutive shares 36,196,247 27,596,259

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended
	Apr. 02, 2024	Mar. 31, 2024	Dec. 31, 2023
Organization And Basis Of Presentation [Line Items]
Cash, cash equivalents, and short-term marketable securities		$ 297,700
Accumulated deficit		(641,030)	$ (606,013)
Proceeds from prepayment of private placement		6,907
2024 Private Placement
Organization And Basis Of Presentation [Line Items]
Proceeds from prepayment of private placement		$ 6,900
2024 Private Placement | Subsequent Event
Organization And Basis Of Presentation [Line Items]
Net proceeds from private placement, after deducting placement agent fees and estimated expenses	$ 43,700
Placement agent fees and estimated expenses	$ 1,300
Common Stock | 2024 Private Placement
Organization And Basis Of Presentation [Line Items]
Stock issued and sold		21,844,660
Price per share		$ 2.06
Common Stock | 2024 Private Placement | Subsequent Event
Organization And Basis Of Presentation [Line Items]
Stock issued and sold	21,844,660
Price per share	$ 2.06

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Mar. 31, 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	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 76,726	$ 93,075	$ 272,756
Restricted cash	408		408
Total cash, cash equivalents and restricted cash	$ 77,134		$ 273,164

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		Mar. 31, 2024		Dec. 31, 2023
Assets:
Total fair value of assets		$ 280,775		$ 312,018
Money Market Funds | Cash and Cash Equivalents
Assets:
Total fair value of assets		58,324	[1]	83,101	[2]
Commercial Paper | Cash and Cash Equivalents
Assets:
Total fair value of assets	[1]	1,492
Commercial Paper | Short-Term Investments
Assets:
Total fair value of assets		100,533	[3]	88,414	[4]
US Treasury Securities | Short-Term Investments
Assets:
Total fair value of assets		73,644	[3]	93,303	[4]
US Treasury Securities | Long-Term Investments
Assets:
Total fair value of assets	[5]			9,642
US Government Agency Securities | Short-Term Investments
Assets:
Total fair value of assets		23,856	[3]	26,824	[4]
Corporate Debt Securities | Short-Term Investments
Assets:
Total fair value of assets		22,926	[3]	10,734	[4]
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total fair value of assets		131,968		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		58,324	[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		73,644	[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	[5]			9,642
Significant Other Observable Inputs (Level 2)
Assets:
Total fair value of assets		148,807		125,972
Significant Other Observable Inputs (Level 2) | Commercial Paper | Cash and Cash Equivalents
Assets:
Total fair value of assets	[1]	1,492
Significant Other Observable Inputs (Level 2) | Commercial Paper | Short-Term Investments
Assets:
Total fair value of assets		100,533	[3]	88,414	[4]
Significant Other Observable Inputs (Level 2) | US Government Agency Securities | Short-Term Investments
Assets:
Total fair value of assets		23,856	[3]	26,824	[4]
Significant Other Observable Inputs (Level 2) | Corporate Debt Securities | Short-Term Investments
Assets:
Total fair value of assets		$ 22,926	[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.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Measurement at fair value, transfers among Level 1, Level 2 or Level 3	$ 0	$ 0
Affini T Therapeutics, Inc.
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investment in equity securities	2,000,000	$ 2,000,000
Adjustments to value of investment in equity securities	$ 0

Marketable Securities - Summary

Marketable Securities - Summary of Marketable Securities Accounted for Available-for-Sale-Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	$ 221,169	$ 228,840
Available for sale securities, Unrealized gains	35	239
Available for sale securities, Unrealized losses	(245)	(162)
Available for sale securities, Estimated fair value	220,959	228,917
US Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, Amortized cost	73,753	93,377
Available for sale securities, Unrealized gains	8	74
Available for sale securities, Unrealized losses	(117)	(148)
Available for sale securities, Estimated fair value	$ 73,644	$ 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	$ 23,859	$ 26,783
Available for sale securities, Unrealized gains	11	45
Available for sale securities, Unrealized losses	(14)	(4)
Available for sale securities, Estimated fair value	$ 23,856	$ 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	$ 22,967	$ 10,719
Available for sale securities, Unrealized gains		15
Available for sale securities, Unrealized losses	(41)
Available for sale securities, Estimated fair value	$ 22,926	$ 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	$ 100,590	$ 88,356
Available for sale securities, Unrealized gains	16	68
Available for sale securities, Unrealized losses	(73)	(10)
Available for sale securities, Estimated fair value	$ 100,533	$ 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		$ 9,605
Available for sale securities, Unrealized gains		37
Available for sale securities, Estimated fair value		$ 9,642
US Treasury Securities | Minimum
Schedule Of Available For Sale Securities [Line Items]
Maturity		1 year
US Treasury Securities | Maximum
Schedule Of Available For Sale Securities [Line Items]
Maturity		2 years

Marketable Securities - Summa_2

Marketable Securities - Summary of Fair Values and Gross Unrealized Losses for Available-for-sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	$ 162,484	$ 105,554
Unrealized losses less than 12 months, Unrealized losses	(245)	(162)
Fair value, Total	162,484	105,554
Unrealized losses, Total	(245)	(162)
US Treasury Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	55,139	74,912
Unrealized losses less than 12 months, Unrealized losses	(117)	(148)
Fair value, Total	55,139	74,912
Unrealized losses, Total	(117)	(148)
US Government Agency Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	18,845	6,950
Unrealized losses less than 12 months, Unrealized losses	(14)	(4)
Fair value, Total	18,845	6,950
Unrealized losses, Total	(14)	(4)
Corporate Debt Securities
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	22,926	748
Unrealized losses less than 12 months, Unrealized losses	(41)
Fair value, Total	22,926	748
Unrealized losses, Total	(41)
Commercial Paper
Debt Securities, Available-for-Sale [Line Items]
Unrealized losses less than 12 months, Fair value	65,574	22,944
Unrealized losses less than 12 months, Unrealized losses	(73)	(10)
Fair value, Total	65,574	22,944
Unrealized losses, Total	$ (73)	$ (10)

Marketable Securities - Additio

Marketable Securities - Additional Information (Details)	Mar. 31, 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	28	22
Available for sale securities, gross unrealized loss position | $	$ 162,484,000	$ 105,554,000
Available of sale securities, unrealized loss position, greater than 12 months, Number of positions | Position	0	0
Available-for-sale securities, accrued interest | $	$ 871,000	$ 1,100,000
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	Mar. 31, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Property and equipment	$ 29,588	$ 29,559
Less accumulated depreciation and amortization	(8,230)	(7,232)
Property and equipment, net	21,358	22,327
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment	5,621	5,620
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment	4,099	4,099
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	18,173	18,173
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	$ 1,695	$ 1,667

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 998,000	$ 894,000

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 9,247	$ 8,803
Accrued compensation	6,095	10,311
Unvested early exercised stock option liability	309	464
Accrued professional services	626	435
Accrued offering costs	178
Accrued property and equipment		13
Other accruals	122	160
Total	$ 16,577	$ 20,186

Asset Acquisitions - Additional

Asset Acquisitions - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended
	Mar. 31, 2021	Nov. 30, 2020	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Asana Merger Agreement
Asset Acquisition [Line Items]
Upfront payment made		$ 20,000,000
Future development and regulatory milestone cash payments maximum		$ 90,000,000
Additional shares required to issue upon achieving development milestone		3,888,889
In-process research and development			$ 0	$ 0
Milestones accrued			0		$ 0
Asana Merger Agreement | Series B-2 Convertible Preferred Stock
Asset Acquisition [Line Items]
Shares issued		4,000,000
Value per share		$ 7.5
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
ELS Purchase Agreement
Asset Acquisition [Line Items]
Upfront payment made	$ 2,000,000
In-process research and development			$ 0	$ 0
ELS Purchase Agreement | Common Stock
Asset Acquisition [Line Items]
Shares issued	500,000
Value per share	$ 3.36
Total fair value of equity	$ 1,700,000

License Agreements - Additional

License Agreements - Additional Information (Details) - USD ($)	1 Months Ended						3 Months Ended
	Dec. 31, 2022	Mar. 31, 2022	Jan. 31, 2021	Apr. 30, 2020	Mar. 31, 2020	Feb. 29, 2020	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
License Agreements [Line Items]
Accounts payable							$ 2,633,000		$ 2,000,000
License Agreement | Novartis Pharma AG
License Agreements [Line Items]
Upfront payment	$ 20,000,000
In-process research and development							0	$ 0
Accrued milestone payment as underlying contingencies							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
Accrued milestone payment as underlying contingencies							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
Accrued milestone payment as underlying contingencies							0		0
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-1 Convertible Preferred Stock and Series B-2 Convertible Preferred Stock
License Agreements [Line Items]
Stock issued, value					$ 2,700,000
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-1 Convertible Preferred Stock and Series B-2 Convertible Preferred Stock | IPO
License Agreements [Line Items]
Conversion of convertible preferred stock into common stock					395,555
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-1 Convertible Preferred Stock
License Agreements [Line Items]
Stock issued, value				$ 1,800,000
Stock issued and sold				356,000
License Agreement | Katmai Pharmaceuticals, Inc. | Series B-2 Convertible Preferred Stock
License Agreements [Line Items]
Stock issued, value			$ 900,000
Stock issued and sold			118,666
License Agreement | Katmai Pharmaceuticals, Inc. | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation					$ 26,000,000
Commercial milestone payments obligation					$ 101,000,000
License Agreement | LifeArc
License Agreements [Line Items]
Upfront payment				$ 0
In-process research and development							0	$ 0
Accrued milestone payment as underlying contingencies							$ 0		$ 0
One-time license payment				75,000
License Agreement | LifeArc | Maximum
License Agreements [Line Items]
Development and regulatory milestone payments obligation				11,000,000
Sales milestone payments obligation				$ 50,000,000

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		5 Months Ended
	Jul. 31, 2021	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2021	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance		49,932,505			42,394,435
Share-based compensation, shares subject to repurchase		247,919			371,876
Stock-based compensation		$ 6,848,000	$ 6,845,000
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		$ 309,000			$ 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		34,647,123			24,970,957
Stock vesting period		4 years
Weighted-average grant date fair value of options granted		$ 1.25	$ 2.94
Unrecognized compensation cost related to unvested stock option grants		$ 55,900,000
Unrecognized compensation cost expected to be recognized as expense, period		2 years 9 months
Intrinsic value of options exercised		$ 47,000	$ 517,000
Share-based compensation, options granted that vest based on performance milestone		9,827,650
Employee Stock Option | Minimum | At the Time Option is Granted
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock		100%
Employee Stock Option | Minimum | For Holders of More Than 10% of Company's Total Combined Voting Power of All Classes of Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock		110%
Employee Stock Option | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, plan expiration period		10 years
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, options granted that vest based on performance milestone				0
2021 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance		13,204,701
Shares of common stock, authorized for issuance	15,150,000
Percentage of outstanding common stock maximum	5%
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,260,000
Unrecognized compensation cost related to unvested stock option grants		$ 1,500,000
Unrecognized compensation cost expected to be recognized as expense, period		1 year 8 months 8 days
Stock-based compensation		$ 342,000	$ 707,000
Share-based payment arrangement, withheld on behalf of employees for future purchase		$ 317,000			$ 46,000
Offering period	24 months
Purchase period	6 months
Shares issued under ESPP		0	0
ESPP | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value of common stock	85%

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock Option Activity (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Outstanding at December 31, 2023	24,970,957
Shares Granted	9,827,650
Shares Exercised	(35,035)
Shares Canceled	(116,449)
Shares Outstanding at March 31, 2024	34,647,123	24,970,957
Shares Options exercisable at March 31, 2024	12,850,952
Weighted-average exercise price, Outstanding at December 31, 2023	$ 4.98
Weighted-average exercise price, Granted	1.71
Weighted-average exercise price, Exercised	0.69
Weighted-average exercise price, Canceled	4.89
Weighted-average exercise price, Outstanding at March 31, 2024	4.06	$ 4.98
Weighted-average exercise price, Options exercisable at March 31, 2024	$ 4.83
Weighted-average remaining contractual term (years), Outstanding	8 years 5 months 8 days	8 years 1 month 13 days
Weighted-average remaining contractual term (years), Options exercisable at March 31, 2024	7 years 3 months 25 days
Aggregate intrinsic value, Outstanding	$ 7,532	$ 4,412
Aggregate intrinsic value, Options exercisable at March 31, 2024	$ 3,916

Stock-based Compensation - Assu

Stock-based Compensation - Assumptions used to Determine Fair Value of Stock Option Grants (Details) - Employee Stock Option	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate, minimum	3.84%	3.46%
Risk-free interest rate, maximum	4.15%	4.22%
Expected volatility, minimum	83.35%	85.52%
Expected volatility, maximum	83.91%	85.81%
Expected dividend yield	0%	0%
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 10 days	6 years 7 days
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	6 years 3 days	6 years 25 days

Stock-based Compensation - Sche

Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 6,848	$ 6,845
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	3,484	3,880
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 3,364	$ 2,965

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Mar. 31, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	49,932,505	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	34,647,123	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	13,204,701	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	2,080,681	2,080,681

Leases - Additional Information

Leases - Additional Information (Details)		1 Months Ended				3 Months Ended
	Jan. 31, 2024 ft²	Apr. 30, 2022	Dec. 31, 2021 USD ($) ft²	Mar. 31, 2021 ft²	Sep. 30, 2020 USD ($) ft²	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Lessee Lease Description [Line Items]
Operating leases cancelable and non-cancellable expiration dates						2032
Operating leases Noncancelable expiration dates						2026
Total lease cost						$ 2,700,000	$ 3,100,000
Operating lease cost						1,900,000	1,900,000
Variable lease costs						916,000	1,200,000
Cash paid for operating leases						2,100,000	863,000
Sublease income						$ 84,000	$ 0
Operating lease, weighted-average remaining lease term						8 years 18 days		8 years 3 months 14 days
Operating lease, weighted-average discount rate						8.96%		8.95%
Operating lease, aggregate monthly payments to lessor						$ 78,370,000
Letter of credit provided to lessor						$ 408,000		$ 408,000
2020 Lease
Lessee Lease Description [Line Items]
Office space leases | ft²					59,407
Lease commencement month and year					2021-08
Operating lease initial term					10 years 9 months
Operating lease, aggregate monthly payments to lessor					$ 51,600,000
Tenant improvement allowance					$ 16,800,000
Term for cancellation of lease					84 months
Notice period for cancellation of lease					12 months
Operating lease cancellation payment					$ 2,500,000
2020 Lease | Letter of Credit
Lessee Lease Description [Line Items]
Letter of credit provided to lessor					$ 408,000
Line of credit facility, expiration date					Jul. 29, 2032
First Amendment to 2020 Lease
Lessee Lease Description [Line Items]
Office space leases | ft²				18,421
Lease commencement month and year		2022-05		2022-02
2021 Lease
Lessee Lease Description [Line Items]
Office space leases | ft²			29,542
Lease commencement month and year			2022-07
Operating lease initial term			124 months
Operating lease option to extend						5 years
Operating lease existence of option to extend [true false]						true
Operating lease, aggregate monthly payments to lessor			$ 34,400,000
Tenant improvement allowance			8,200,000
Prepaid rent						$ 5,100,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]						Operating Lease, Right-of-Use Asset
2021 Lease | Other Assets
Lessee Lease Description [Line Items]
Security deposit paid			$ 874,000
2024 Lease
Lessee Lease Description [Line Items]
Sublease income						$ 84,000
Office space leases | ft²	10,000
Operating lease initial term	3 years
Operating lease existence of option to extend [true false]	true
Operating sublease existence of option to terminate [true false]	true

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments under Operating Leases (Details) $ in Thousands	Mar. 31, 2024 USD ($)
Leases [Abstract]
2024 (remaining nine months)	$ 6,602
2025	9,024
2026	9,170
2027	9,199
2028	9,277
Thereafter	35,098
Total lease payments	78,370
Less: Amount representing interest	(23,433)
Operating lease liabilities	$ 54,937

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Provision for federal income taxes	$ 0	$ 0
Provision for state income taxes	0	0
Provision for foreign income taxes	0	0
Interest or penalties related to income taxes	$ 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
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net Income (Loss)	$ (35,017)	$ (33,199)
Weighted-average shares of common stock used in computing net loss per share, basic	151,161,741	149,504,216
Weighted-average shares of common stock used in computing net loss per share, diluted	151,161,741	149,504,216
Net loss per share, basic	$ (0.23)	$ (0.22)
Net loss per share, diluted	$ (0.23)	$ (0.22)

Net Loss Per Share - Anti-dilut

Net Loss Per Share - Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	36,196,247	27,596,259
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	34,647,123	25,892,271
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	247,919	948,179
Estimated Shares Purchasable Under the ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	1,301,205	755,809

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended
	Apr. 30, 2023	Mar. 31, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Prepaid expenses and other current assets		$ 8,938,000	$ 8,326,000
Affini T Therapeutics, Inc.
Related Party Transaction [Line Items]
Investment in equity securities		$ 2,000,000
Erasca Foundation
Related Party Transaction [Line Items]
Amount donated to related party	$ 125,000

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - 2024 Private Placement - USD ($) $ / shares in Units, $ in Millions		1 Months Ended
	Apr. 02, 2024	Mar. 31, 2024
Subsequent Event
Subsequent Event [Line Items]
Net proceeds from private placement, after deducting placement agent fees and estimated expenses	$ 43.7
Common Stock
Subsequent Event [Line Items]
Stock issued and sold		21,844,660
Price per share		$ 2.06
Common Stock | Subsequent Event
Subsequent Event [Line Items]
Stock issued and sold	21,844,660
Price per share	$ 2.06