Verve Therapeutics (VERV) 10-K 27 Feb 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	VERVE THERAPEUTICS, INC.
Entity Central Index Key	0001840574
Trading Symbol	VERV
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	true
Document Financial Statement Error Correction [Flag]	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float		$ 939.9
Entity Common Stock, Shares Outstanding	83,619,279
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common stock, par value $0.001 per share
Entity File Number	001-40489
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-4800132
Entity Address, Address Line One	201 Brookline Avenue, Suite 601
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02215
City Area Code	617
Local Phone Number	603-0070
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement that will be filed for the 2024 Annual Meeting of Stockholders which the registrant intends to file with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year ended December 31, 2023 , are incorporated by reference in Part III of this Annual Report on Form 10-K
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Boston, Massachusetts

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 206,180	$ 115,412
Marketable securities	417,770	439,396
Collaboration receivable	5,897	1,012
Prepaid expenses and other current assets	8,102	7,339
Total current assets	637,949	563,159
Property and equipment, net	22,505	18,778
Restricted cash	4,774	4,824
Operating lease right-of-use assets	85,295	91,877
Other long term assets	2,165	585
Total assets	752,688	679,223
Current liabilities:
Accounts payable	6,636	2,424
Accrued expenses	20,178	20,767
Operating lease obligations, current portion	10,192	11,904
Total current liabilities	37,006	35,095
Long-term lease liability	64,715	70,014
Deferred revenue, non-current	48,556	20,014
Success payment liability	2,720	2,885
Other long term liabilities	189	283
Total liabilities	153,186	128,291
Commitments and contingencies (See Note 7 and 8)
Stockholders' equtiy
Preferred stock, $0.001 par value; 5,000,000 shares authorized, no shares issued and oustanding	0	0
Common stock, $0.001 par value; 200,000,000 shares authorized, 81,969,693 and 61,730,816 shares issued and outstanding at December 31, 2023 and 2022, respectively	82	62
Additional paid-in capital	1,143,453	895,801
Accumulated other comprehensive loss	272	(694)
Accumulated deficit	(544,305)	(344,237)
Total stockholders' equity	599,502	550,932
Total liabilities and stockholders' equity	$ 752,688	$ 679,223

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, value per share	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	81,969,693	61,730,816
Common stock, shares outstanding	81,969,693	61,730,816

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Collaborations revenue	$ 11,758	$ 1,941	$ 0
Operating expenses:
Research and development	184,946	130,095	68,202
General and administrative	49,936	37,533	18,865
Total operating expenses	234,882	167,628	87,067
Loss from operations	(223,124)	(165,687)	(87,067)
Other income (expense):
Change in fair value of antidilution rights liability	0	0	(25,574)
Change in fair value of success payment liability	165	1,486	(7,815)
Interest and other income, net	23,166	6,867	142
Total other income (expense), net	23,331	8,353	(33,247)
Loss before provision for income taxes	(199,793)	(157,334)	(120,314)
Provision for income taxes	(275)	(53)	0
Net loss	$ (200,068)	$ (157,387)	$ (120,314)
Net loss per common share, basic	$ (3.12)	$ (2.91)	$ (4.48)
Net loss per common share, diluted	$ (3.12)	$ (2.91)	$ (4.48)
Weighted-average common shares used in net loss, basic	64,175,137	54,023,653	26,872,036
Weighted-average common shares used in net loss, diluted	64,175,137	54,023,653	26,872,036
Comprehensive Loss:
Net Income (Loss)	$ (200,068)	$ (157,387)	$ (120,314)
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	966	(466)	(236)
Comprehensive loss	$ (199,102)	$ (157,853)	$ (120,550)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Preferred Stock
Beginning balance at Dec. 31, 2020	$ (63,909)	$ 3	$ 2,616	$ 8	$ (66,536)	$ 125,160
Beginning balance (in shares) at Dec. 31, 2020		2,585,789				179,519,032
Issuance of Series B convertible preferred stock, net of issuance costs of $241						$ 93,759
Issuance of Series B convertible preferred stock, net of issuance costs (in shares)						77,163,022
Conversion of convertible preferred stock to common stock upon closing of initial public offering	218,919	$ 28	218,891			$ (218,919)
Conversion of convertible preferred stock to common stock upon closing of initial public offering (in shares)		27,720,923				(256,682,054)
Issuance of common stock from initial public offering, net of issuance costs of $25,098	281,584	$ 16	281,568
Issuance of common stock from initial public offering, net of issuance costs of (in shares)		16,141,157
Issuances of common stock to licensor institutions	32,490	$ 1	32,489
Issuances of common stock to licensor institutions (in shares)		878,098
Vesting of restricted common stock (in shares)		537,633
Exercise of stock options	966	$ 1	965
Exercise of stock options (in shares)		599,838
Purchase of common stock under employee stock purchase plan	780		780
Purchase of common stock under employee stock purchase plan (shares)		48,297
Unrealized loss on available-for-sale securities	(236)			(236)
Stock-based compensation	7,072		7,072
Net Income (Loss)	(120,314)				(120,314)
Ending balance at Dec. 31, 2021	357,352	$ 49	544,381	(228)	(186,850)
Ending balance (in shares) at Dec. 31, 2021		48,511,735
Issuance of common stock from initial public offering, net of issuance costs of $25,098	242,826	$ 10	242,816
Issuance of common stock from initial public offering, net of issuance costs of (in shares)		9,583,334
Issuances of common stock to licensor institutions	39,986	$ 2	39,984
Issuances of common stock to licensor institutions (in shares)		1,519,756
Issuance of common stock from At-the-Market offering, net of issuance costs of , (In Shares)		1,280,168
Issuance of common stock from At-the-Market offering, net of issuance costs	42,900	$ 1	42,899
Vesting of restricted common stock (in shares)		6,375
Exercise of stock options	2,175		2,175
Exercise of stock options (in shares)		743,638
Purchase of common stock under employee stock purchase plan	1,069		1,069
Purchase of common stock under employee stock purchase plan (shares)		85,810
Unrealized loss on available-for-sale securities	(466)			(466)
Stock-based compensation	22,477		22,477
Net Income (Loss)	(157,387)				(157,387)
Ending balance at Dec. 31, 2022	$ 550,932	$ 62	895,801	(694)	(344,237)
Ending balance (in shares) at Dec. 31, 2022	61,730,816	61,730,816
Issuance of common stock from initial public offering, net of issuance costs of $25,098	$ 134,736	$ 14	134,722
Issuance of common stock from initial public offering, net of issuance costs of (in shares)		14,375,000
Issuance of common stock from At-the-Market offering, net of issuance costs of , (In Shares)		1,500,685
Issuance of common stock from At-the-Market offering, net of issuance costs	20,570	$ 2	20,568
Vesting of restricted common stock (in shares)		149,456
Exercise of stock options	$ 1,200		1,200
Exercise of stock options (in shares)	240,182	240,182
Purchase of common stock under employee stock purchase plan	$ 1,379		1,379
Purchase of common stock under employee stock purchase plan (shares)		124,442
Issuance of common stock in connection with the Lilly Stock Agreements, Shares		3,849,112
Issuance of common stock in connection with the Lilly Agreement, Cost	54,671	$ 4	54,667
Unrealized loss on available-for-sale securities	966			966
Stock-based compensation	35,116		35,116
Net Income (Loss)	(200,068)				(200,068)
Ending balance at Dec. 31, 2023	$ 599,502	$ 82	$ 1,143,453	$ 272	$ (544,305)
Ending balance (in shares) at Dec. 31, 2023	81,969,693	81,969,693

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Issuance costs of series B convertible preferred stock			$ 241
Issuance costs of common stock from initial public offering	$ 9,013	$ 15,924	$ 25,098
Issuance of common stock from At-the-Market offering	$ 728,000	$ 1,722,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (200,068)	$ (157,387)	$ (120,314)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	5,455	2,804	1,535
Non-cash lease expense	6,792	3,907	1,842
Net amortization of premium (accretion of discount) on marketable securities	(14,382)	(1,027)	1,508
Stock-based compensation	35,116	22,477	7,072
Change in fair value of antidilution rights	0	0	25,574
Change in fair value of success payments liabilities	(165)	(1,486)	7,815
Changes in operating assets and liabilities:
Collaboration receivable	(5,892)	(1,012)	0
Prepaid expenses and other current assets	(1,406)	(9,436)	(7,528)
Accounts payable	3,910	(5,216)	6,829
Accrued expenses and other liabilities	(231)	7,041	5,977
Success of payment liability	0	0	(6,250)
Deferred revenue	28,542	20,014	0
Operating lease liabilities	(7,220)	(3,011)	(1,940)
Net cash used in operating activities	(149,549)	(122,332)	(77,880)
Cash flows from investing activities:
Purchases of property and equipment	(9,283)	(13,232)	(4,359)
Purchases of marketable securities	(517,140)	(479,401)	(371,494)
Maturities of marketable securities	554,113	336,678	136,755
Net cash provided by (used in) investing activities	27,690	(155,955)	(239,098)
Cash flows from financing activities
Proceeds from issuance of Preferred Stock, net	0	0	93,759
Proceeds from the issuance of common stock in connection with collaboration agreements	31,710	39,986	0
Proceeds from issuance of common shares, net of commissions	178,746	286,509	285,214
Payment of equity offering costs	(458)	(783)	(3,630)
Proceeds from exercise of stock options	1,200	2,175	966
Proceeds from purchase of shares through employee stock purchase plan	1,379	1,069	780
Net cash provided by financing activities	212,577	328,956	377,089
Increase (decrease) in cash, cash equivalents and restricted cash	90,718	50,669	60,111
Cash, cash equivalents and restricted cash—beginning of period	120,236	69,567	9,456
Cash, cash equivalents and restricted cash—end of period	210,954	120,236	69,567
Supplemental disclosure of noncash investing and finnacing activities:
Property and equipment additions included in accounts payable and accrued expenses	1,534	1,706	503
Financing costs included in accounts payable and accrued expenses	21	0	0
Conversion of convertible preferred stock to common stock upon closing of initial public offering	0	0	218,919
Settlement of derivative liability by issuing common stock	0	0	32,490
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 0	$ 83,417	$ 809

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pay vs Performance Disclosure
Net Income (Loss)	$ (200,068)	$ (157,387)	$ (120,314)	$ (200,068)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	The following table describes, for the three months ended December 31, 2023, each trading arrangement for the sale or purchase of our securities adopted or terminated by our directors and officers that is either (1) a contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c), or a Rule 10b5-1 trading arrangement, or (2) a “non-Rule 10b5-1 trading arrangement” (as defined in Item 408(c) of Regulation S-K): Name (Title) Action Taken (Date of Action) Type of Trading Arrangement Nature of Trading Arrangement Duration of Trading Arrangement Aggregate Number of Shares of Common Stock Sekar Kathiresan Chief Executive Officer and Director Adoption 12/22/2023 Rule 10b5-1 trading arrangement Sale Until December 31, 2025 , or such earlier date upon which all transactions are completed or expire without execution Up to 243,672 Burt Adelman Director Adoption 12/26/2023 Rule 10b5-1 trading arrangement Sale Until December 31, 2024 , or such earlier date upon which all transactions are completed or expire without execution Up to 100,000
Sekar Kathiresan [Member]
Trading Arrangements, by Individual
Name	Sekar Kathiresan
Title	Chief Executive Officer and Director
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	12/22/2023
Arrangement Duration	741 days
Aggregate Available	243,672
Burt Adelman [Member]
Trading Arrangements, by Individual
Name	Burt Adelman
Title	Director
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	12/26/2023
Arrangement Duration	372 days
Aggregate Available	100,000

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the business and basis of presentation Organization Verve Therapeutics, Inc. (the “Company” or “Verve”) is a clinical-stage genetic medicines company pioneering a new approach to the care of cardiovascular disease, transforming treatment from chronic management to single-course gene editing medicines. The Company was incorporated on March 9, 2018 as Endcadia, Inc., a Delaware corporation, and began operations shortly thereafter. In January 2019, the Company amended its certificate of incorporation to change its name to Verve Therapeutics, Inc. The Company’s principal offices are located in Boston, Massachusetts. Liquidity and capital resources Since its inception, the Company has devoted its efforts principally to research and development and raising capital. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry including, but not limited to, technical risks associated with the successful research, development and manufacturing of product candidates, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Current and future programs will require significant research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. The Company expects that its cash, cash equivalents and marketable securities of $ 624.0 million as of December 31, 2023, will be sufficient to fund its operations and capital expenditure requirements beyond the next 12 months from the date of issuance of these financial statements. The Company will need additional financing to support its continuing operations and pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, it expects to finance its operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and marketing, distribution or licensing arrangements. The Company may be unable to raise additional funds or enter into such other agreements when needed on favorable terms or at all. The inability to raise capital as and when needed could have a negative impact on the Company’s financial condition and its ability to pursue its business strategy. The Company will need to generate significant revenue to achieve profitability, and it may never do so. Basis of presentation The accompanying consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. S ummary of significant accounting policies Principles of consolidation The accompanying consolidated financial statements include the accounts of Verve and its wholly owned subsidiary, Verve Securities Corporation. All intercompany transactions and balances have been eliminated in consolidation. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities as of and during the reporting period. The Company bases its estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. Cash and cash equivalents Cash and cash equivalents consist of standard checking accounts and money market account funds that invest primarily in U.S. government-backed securities and treasuries. The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents are stated at cost, which is substantially equivalent to fair value. Restricted cash Restricted cash represents collateral provided for a letter of credit issued as a security deposit in connection with the Company’s leases of its corporate facilities. A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: December 31, (in thousands) 2023 2022 Cash and cash equivalents $ 206,180 $ 115,412 Restricted cash 4,774 4,824 Total cash, cash equivalents and restricted cash $ 210,954 $ 120,236 Marketable securities The Company classifies marketable securities with a remaining maturity when purchased of greater than three months as available-for-sale. Available-for-sale securities are maintained by the Company’s investment managers and consist of U.S. treasury bills and U.S agency securities. The Company classifies investments available to fund current operations as current assets on its consolidated balance sheets. Available-for-sale securities are carried at fair value with the unrealized gains and losses included in accumulated other comprehensive income (loss) as a component of stockholders’ equity until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income and/or expense over the life of the instrument. Realized gains and losses are determined using the specific identification method and are included in other income (expense). Marketable securities are evaluated for impairment at the end of each reporting period. Impairment is evaluated considering numerous factors, and their relative significance varies depending on the situation. Factors considered include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospects of the issuer, and the Company's intent and ability to hold the investment to allow for an anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit- related is recognized in other comprehensive (loss) income, net of applicable taxes. Concentrations of credit risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash, cash equivalents, marketable securities, collaboration receivable, and restricted cash. Periodically, the Company may maintain deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality, and the Company has not experienced any losses on these deposits. The Company generally invests its excess capital in money market funds, U.S. treasury bills and agency securities, all of which are subject to minimal credit and market risk. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. Deferred offering costs The Company capitalized incremental legal, professional accounting and other third-party fees that were directly associated with the stock offerings as other non-current assets until the offerings were consummated. After consummation of the offerings, these costs were recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering. Fair value of financial instruments ASC Topic 820, Fair Value Measurement (“ASC 820”), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the assets or liability and are developed based on the best information available in the circumstances. ASC 820 identifies fair value as the price that would be received to sell an asset or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tiered value hierarchy that distinguishes between the following: Level 1—Quoted market prices in active markets for identical assets or liabilities. Level 2—Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Level 3—Unobservable inputs for the asset or liability (i.e. supported by little or no market activity). Level 3 inputs include management’s own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk). To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. There have been no changes to the valuation methods utilized by the Company during the years ended December 31, 2023, 2022 and 2021. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of financial instruments between levels during the years ended December 31, 2023 and 2022 . Property and equipment, net Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset as follows: Asset category Estimated useful life Computer equipment and software 3 years Office furniture 4 years Laboratory equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are charged to expense as incurred. Impairment of long-lived assets The Company evaluates its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. There were no impairment losses recognized during the years ended December 31, 2023, 2022 and 2021 . Freestanding financial instruments and derivatives The Company has identified the following financial instruments, which are recorded as liabilities in the balance sheet and separately accounted for at fair value. Pursuant to license agreements with (i) the President and Fellows of Harvard College (“Harvard”) and The Broad Institute, Inc. (“Broad”) (“Harvard/Broad License Agreement”) and (ii) Broad (“Broad License Agreement”) (see Note 8, License agreements), the following financial instruments were issued by the Company. Antidilution Rights —The antidilution rights represented the obligation to issue additional shares of common stock to Harvard and Broad following the completion of additional financings, including the Company’s initial public offering. These antidilution rights were accounted for under ASC 815, Derivatives and Hedging ("ASC 815") , and were initially recorded at fair value with a corresponding charge to research and development expense. The liability was remeasured at each reporting period, with changes in fair value recognized in other income (expense) in the statement of operations and comprehensive loss while this instrument was outstanding. The obligation was satisfied in full upon the issuance of an aggregate of an additional 878,098 shares of common stock upon the closing of the Company's initital public offering ("IPO") in June 2021. Success Payments —The Company is obligated to pay to Harvard and Broad tiered success payments in the event the Company’s average market capitalization exceeds specified thresholds ascending from a mid ten-digit dollar amount to $ 10.0 billion, or sale of the Company for consideration in excess of those thresholds. In the event of a change of control of the Company or a sale of the Company, the Company is required to pay in cash within a specified period following such event. Otherwise, the payments may be settled at the Company’s option in either cash or shares of the Company’s common stock. The success payments are accounted for under ASC 815 and were initially recorded at fair value with a corresponding charge to research and development expense. The liability is remeasured at each reporting period with all changes in value recognized in other income (expense) in the statement of operations and other comprehensive loss. During the year ended December 31, 2021, certain success payment obligations were triggered, and amounts paid to Harvard and Broad totaled $ 6.3 million. These amounts were settled in cash in November 2021. No success payments were triggered or paid during the years ended December 31, 2023 and 2022. The Company will continue to adjust the liability for changes in fair value until the earlier of the achievement or expiration of the remaining success payment obligation. Refer to Note 5, Fair value of financial instruments, for additional discussion . Revenue Recognition The Company enters into collaboration agreements which are within the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), under which the Company licenses rights to certain of the Company’s product candidates and performs research and development services. The terms of these arrangements typically include payment of one or more of the following: non-refundable, upfront fees; reimbursement of research and development costs; development, regulatory, and commercial milestone payments; and royalties on net sales of licensed products. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine the appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, the Company performs the following five steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect consideration it is entitled to in exchange for the goods or services it transfers to the customer. The promised goods or services in the Company’s arrangements typically consist of license rights to the Company’s intellectual property and research and development services. The Company provides options to additional items in the contracts, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. The Company evaluates the customer options for material rights, or options to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. Performance obligations are promised goods or services in a contract to transfer a distinct good or service to the customer and are considered distinct when (i) the customer can benefit from the good or service on its own or together with other readily available resources and (ii) the promised good or service is separately identifiable from other promises in the contract. In assessing whether promised goods or services are distinct, the Company considers factors such as the stage of development of the underlying intellectual property, the capabilities of the customer to develop the intellectual property on its own or whether the required expertise is readily available and whether the goods or services are integral or dependent to other goods or services in the contract. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the number of potential payments and the likelihood that the payments will be received. The Company utilizes either the most likely amount method or expected amount method to estimate the amount expected to be received based on which method best predicts the amount expected to be received. The amount of variable consideration which is included in the transaction price may be constrained and is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. The Company’s contracts often include development and regulatory milestone payments which are assessed under the most likely amount method and constrained if it is probable that a significant revenue reversal would occur. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenues in the period of adjustment. To date, the Company has not recognized any consideration related to the achievement of development, regulatory, or commercial milestone revenue resulting from any of the Company’s collaboration arrangements. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any consideration related to sales-based royalty revenue resulting from any of the Company’s collaboration arrangements. The Company allocates the transaction price based on the estimated stand-alone selling price of each of the performance obligations. The Company must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. The Company utilizes key assumptions to determine the stand-alone selling price for service obligations, which may include other comparable transactions, pricing considered in negotiating the transaction and the estimated costs. Additionally, in determining the standalone selling price for material rights, the Company utilizes comparable transactions, clinical trial success probabilities, and estimates of option exercise likelihood. Variable consideration is allocated specifically to one or more performance obligations in a contract when the terms of the variable consideration relate to the satisfaction of the performance obligation and the resulting amounts allocated are consistent with the amounts the Company would expect to receive for the satisfaction of each performance obligation. The consideration allocated to each performance obligation is recognized as revenue when control is transferred for the related goods or services. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Upfront payments and fees are recorded as deferred revenue upon receipt or when due until the Company performs its obligations under these arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. Research and development costs Research and development costs are charged to expense as incurred. Research and development costs consist of costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, third-party license fees related to technology with no alternative future use, laboratory supplies, depreciation, manufacturing expenses, preclinical, clinical and regulatory expenses, consulting and other contracted services. Costs for certain research and development activities are recognized based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the financial statements as prepaid or accrued research and development. Stock-based compensation The Company’s stock-based compensation program allows for grants of certain equity awards. Grants are awarded to employees and non-employees, including directors. The Company accounts for its stock-based compensation in accordance with ASC Topic 718, Compensation-Stock Compensation (‘‘ASC 718’’). ASC 718 requires all stock-based payments to employees, non-employees and directors, to be recognized as expense in the consolidated statements of operations and comprehensive loss based on their grant date fair values. The Company estimates the fair value of options granted using the Black-Scholes option pricing model (‘‘Black-Scholes’’) for stock option grants to both employees and non-employees. The fair value of the Company’s common stock is used to determine the fair value of restricted stock unit awards. The Company estimates the fair value of the Company’s restricted stock unit awards on the date of grant using the closing price of the Company’s common stock on that date. The Company’s stock-based compensation awards are subject to either service or performance-based vesting conditions. Compensation expense related to awards to employees, directors and non-employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards to employees with performance-based vesting conditions is recognized over the implied service period when achievement of the performance-based milestones is deemed probable. The Company uses judgment to determine whether and, if so, how many awards are deemed probable of vesting at each reporting period. The estimation of fair value for stock-based compensation requires management to make estimates and judgments about, among other things, the estimated life of options and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized. Prior to the Company's IPO in June 2021, there was no public market for its common stock. As a result, prior to the IPO, the estimated fair value of the Company's common stock was determined by its board of directors as of the date of each option grant, with input from management, considering the Company's most recently available third-party valuations of common stock and its board of directors' assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the date of grant. Following the Company's IPO, the fair value of its common stock is determined based on the closing price of the Company's common stock as reported on the Nasdaq Global Select Market . Leases The Company accounts for leases in accordance with ASC Topic 842 Leases ("ASC 842"). At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on specific facts and circumstances, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. If an arrangement is determined to be or contain a lease, the lease is assessed for classification as either an operating or finance lease at the lease commencement date, defined as the date on which the leased asset is made available for use by the Company, based on the economic characteristics of the lease. The lease liability is measured at the present value of future lease payments, discounted using the discount rate as of the lease commencement date. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the incremental borrowing rate, which is the rate incurred to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company recognizes a corresponding lease right of use (“ROU”) asset, initially measured as the amount of lease liability, adjusted for any initial lease costs or lease payments made before or at the commencement of the lease, and reduced by any lease incentives. The Company’s leases consist of only operating leases. Operating leases are recognized on the balance sheet as ROU lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while certain variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis. Income taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the Company’s financial statements and tax returns. Deferred tax assets and liabilities are determined based upon the differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities and for loss and credit carryforwards, using enacted tax rates expected to be in effect in the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that these assets may not be realized. The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more-likely-than-not recognition threshold is calculated as the largest amount that is more than 50 % likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. Comprehensive loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2023, 2022 and 2021, the Company’s only element of other comprehensive loss was unrealized gains and losses on marketable securities. Net loss per share The Company follows the two-class method when computing net loss per share, as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding for the period. Diluted net loss is computed by adjusting net loss to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share is computed by dividing the diluted net loss by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents. In periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported a net loss for the years ended December 31, 2023, 2022 and 2021 . Segment and geographic information Operating segments are defined as components of an entity about which separate discrete information is available for evaluation by the chief operating decision maker (“CODM”), or decision-making group, in deciding how to allocate resources and in assessing performance. The CODM is the Company’s Chief Executive Officer. The Company views its operations as and manages its business in one operating segment operating exclusively in the United States. Subsequent events The Company performs an evaluation of all subsequent events after the balance sheet date through the date of issuance of the consolidated financial statements to ensure appropriate disclosure of events both recognized in the consolidated financial statements and events which occurred subsequently but were not recognized in the consolidated financial statements. Recently adopted accounting pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that was previously used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, this standard requires allowances to be recorded instead of reducing the amortized cost of the investment. The new standard became effective for the Company on January 1, 2023. Based on the Company’s analysis, the adoption of this standard did not have a material impact on the Company’s financial statements.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	3. Marketable securities Marketable securities by security type consisted of the following: December 31, 2023 (in thousands) Amortized Gross Gross Fair U.S. treasury bills and notes $ 147,978 $ 144 $ ( 15 ) $ 148,107 U.S. agency securities 269,520 277 ( 134 ) 269,663 Total $ 417,498 $ 421 $ ( 149 ) $ 417,770 December 31, 2022 (in thousands) Amortized Gross Gross Fair U.S. treasury bills and notes $ 228,432 $ 13 $ ( 301 ) $ 228,144 U.S. agency securities 211,658 68 ( 474 ) 211,252 Total $ 440,090 $ 81 $ ( 775 ) $ 439,396 The remaining contractual maturities of all marketable securities were less than 24 months as of December 31, 2023 and 2022 . The unrealized loss on the Company’s marketable securities of $ 0.1 million and $ 0.8 million as of December 31, 2023 and December 31, 2022, respectively, was caused by interest rate increases which resulted in the decrease in market value of these securities. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity, the Company did not consider those marketable securities to be other-than-temporarily impaired at December 31, 2023 and 2022 . None of the Company’s marketable securities have been in a continuous unrealized loss position for 12 months or greater as of December 31, 2023 or 2022.

Property and equipment, net

Property and equipment, net	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment, net	4. P roperty and equipment, net Property and equipment, net, consisted of the following: December 31, (in thousands) 2023 2022 Lab equipment 28,851 20,379 Leasehold improvements 726 266 Furniture and fixtures 2,323 2,294 Computer equipment 997 826 Total property and equipment 32,897 23,765 Less accumulated depreciation ( 10,392 ) ( 4,987 ) Property and equipment, net $ 22,505 $ 18,778 Year ended December 31, (in thousands) 2023 2022 2021 Depreciation expense $ 5,455 $ 2,804 $ 1,535

Fair value of financial instrum

Fair value of financial instruments	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Disclosure - Fair Value of Financial Instruments	5. f air value of financial instruments The Company’s financial instruments that are measured at fair value on a recurring basis consist of money market funds, marketable securities, and a derivative liability (success payment liability) pursuant to the Harvard/ Broad License Agreement. The following tables set forth the fair value of the Company’s financial instruments by level within the fair value hierarchy: As of December 31, 2023 (in thousands) Fair Level 1 Level 2 Level 3 Assets Money market funds $ 120,987 $ 120,987 $ — $ — Marketable securities: U.S. treasury bills and notes 148,107 — 148,107 — U.S. agency securities 269,663 — 269,663 — Total assets $ 538,757 $ 120,987 $ 417,770 $ — Liabilities Success payment liability $ 2,720 — — $ 2,720 Total liabilities $ 2,720 $ — $ — $ 2,720 As of December 31, 2022 (in thousands) Fair Level 1 Level 2 Level 3 Assets Money market funds $ 105,303 $ 105,303 $ — $ — Marketable securities: U.S. treasury bills and notes 228,144 — 228,144 — U.S. agency securities 211,252 — 211,252 — Total assets $ 544,699 $ 105,303 $ 439,396 $ — Liabilities Success payment liability $ 2,885 $ — $ — $ 2,885 Total liabilities $ 2,885 $ — $ — $ 2,885 Cash Equivalents —Cash equivalents of $ 121.0 million and $ 105.3 million as of December 31, 2023 and 2022, respectively, consisted of money market funds and are classified within Level 1 of the fair value hierarchy because they are valued using quoted market prices in active markets. Marketable Securities —The Company measures its marketable securities at fair value on a recurring basis and classifies those instruments within Level 2 of the fair value hierarchy. Marketable securities are classified within Level 2 of the fair value hierarchy because pricing inputs are other than quoted prices in active markets, which are either directly or indirectly observable as of the reporting date, and fair value is determined through the use of models or other valuation methodologies. Success Payment Liability — The Company is obligated to pay to Harvard and Broad tiered success payments in the event its average market capitalization exceeds specified thresholds for a specified period of time ascending from a mid ten-digit dollar amount to $ 10.0 billion, or sale of the Company for consideration in excess of those thresholds. In the event of a change of control or a sale of the Company, the Company is required to pay success payments in cash within a specified period following such event. Otherwise, the success payments may be settled at the Company’s option in either cash or shares of its common stock, or a combination of cash and shares of its common stock. The maximum aggregate success payments that could be payable by the Company is $ 31.3 million (after termination of the Broad License Agreement). The success payment liability is stated at fair value and is considered Level 3 because its fair value measurement is based, in part, on significant inputs not observed in the market. The Company used a Monte Carlo simulation model, which models the value of the liability based on several key variables, including probability of event occurrence, timing of event occurrence, as well as the value of the Company’s common stock. The Company remeasured the liability at fair value with the decreases of $ 0.2 million and $ 1.5 million recorded to other income for the years ended December 31, 2023 and 2022, respectively. The Company remeasured the liability at fair value with the increase of $ 7.8 million recorded to other expense for the year ended December 31, 2021. In September 2021, multiple success payments were triggered and amounts due to Harvard and Broad totaled $ 6.3 million. These amounts were settled in cash in November 2021. The Company will continue to adjust the remaining success payment liability for changes in fair value until the earlier of the achievement or expiration of the obligation. The primary inputs used in valuing the success payments liability associated with the Company’s realization of a certain valuation threshold through either a sale of the Company’s preferred stock or a company sale at December 31, 2023, 2022 and 2021, were as follows: At At At Fair value of common stock (per share) $ 13.94 $ 19.35 $ 36.87 Equity volatility 83 % 84 % 77 % In February 2021, the Company provided written notice to Broad of its election to terminate the Broad License Agreement, which termination became effective in June 2021. The reconciliation of changes in the fair value of financial instruments based on Level 3 inputs were as follows: (in thousands) Success Balance at December 31, 2021 $ 4,371 Change in fair value ( 1,486 ) Balance at December 31, 2022 $ 2,885 Change in fair value ( 165 ) Balance at December 31, 2023 $ 2,720

Accrued expenses

Accrued expenses	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses	6. Accrued expenses Accrued expenses consisted of the following: December 31, (in thousands) 2023 2022 Employee compensation and related benefits $ 12,342 $ 9,124 Accrued external research and development expenses 4,856 8,919 Professional fees 1,492 1,193 License and milestone payments 500 310 Other 988 1,221 Total $ 20,178 $ 20,767

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases	7. Leases The Company’s operating lease activity is comprised of non-cancelable facility leases for office and laboratory space in Boston, Massachusetts. The Company has also entered into multiple contract research and contract manufacturing service agreements with third parties which contain embedded leases within the scope of ASC 842. The embedded leases are considered short term leases, as the contractual terms are twelve months or less. Accordingly, no lease liability or ROU asset has been recorded. The components of operating lease cost were as follows: (in thousands) December 31, 2023 December 31, 2022 Operating lease costs $ 12,936 $ 5,946 Variable lease costs 3,854 1,601 Short term lease costs 1,259 698 Total $ 18,049 $ 8,245 Supplemental cash flow information related to operating leases was as follows: (in thousands) December 31, 2023 December 31, 2022 Cash paid for amounts included in the measurements of lease liabilities: Operating cash flows related to operating leases $ 12,550 $ 5,050 As of December 31, 2023, the Company’s operating leases were measured using a weighted-average incremental borrowing rate of 7.89 % over a weighted-average remaining lease term of 9 years. On August 19, 2021, the Company entered into a lease agreement with ARE-MA Region No. 87 Tenant, LLC, a Delaware limited liability company (the “Landlord”), pursuant to which the Company leased approximately 104,933 square feet of office and laboratory space located at 201 Brookline Avenue, Boston, Massachusetts (the “Boston Lease”), further amended in January 2022 to include an additional 249 square feet, for a total of 105,182 square feet (the “Premises”). In June 2022, the Company entered into a second amendment to specify separate target commencement dates for certain areas of the Premises. The Premises were first made available to the Company in August 2022. Upon commencement of the lease, the Company recorded an operating lease ROU asset of $ 91.8 million and a total lease liability of $ 80.8 million. The Company’s obligation for the payment of base rent for the Premises began in January 2023 (the “Rent Commencement Date”). Base rent is initially $ 0.8 million per month, and will increase by approximately 3 % per annum. The Boston Lease has a term of 10 years, measured from the Rent Commencement Date. The Company has the option to extend the term of the Boston Lease for a period of an additional five years . Under the terms of the Boston Lease, the Landlord made $ 21.0 million in certain tenant improvements to the Premises to suit the Company’s use (the “Tenant Improvement Allowance”), which amount is included in the base rent set forth in the Boston Lease. In connection with its entry into the Boston Lease and as a security deposit, the Company has provided the Landlord a letter of credit in the amount of approximately $ 4.8 million, which may be reduced to approximately $ 3.5 million on the expiration of the 36-month anniversary of the Rent Commencement Date so long as there are, and have been, no defaults by the Company under the terms of the Boston Lease. The Company also paid a deposit in the amount of $ 0.8 million, which is equal to the first month of base rent. The Landlord has the right to terminate th e Boston Lease upon customary events of default. Future minimum commitments under non-cancellable leases as of December 31, 2023 were as follows: Years ending December 31, Amount (in thousands) 2024 $ 10,563 2025 10,868 2026 11,183 2027 11,506 2028 11,839 Thereafter 50,075 Total lease payments $ 106,034 Less: interest ( 31,127 ) Present value of operating lease liabilities $ 74,907

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2023
License Agreement [Abstract]
License Agreement	8. License agreements Harvard/Broad license agreement and Broad license agreement In March 2019, the Company simultaneously entered into the Harvard/Broad License Agreement and Broad License Agreement (the “license agreements”) for certain base editing technologies pursuant to which the Company received exclusive, worldwide, sublicensable, royalty-bearing licenses under specified patent rights to develop and commercialize licensed products and nonexclusive, worldwide, sublicensable, royalty-bearing licenses under certain patent rights to research and develop licensed products. The Company agreed to use commercially reasonable efforts to develop licensed products in accordance with the development plans, to introduce any licensed products that gain regulatory approval into the commercial market, to market licensed products that have gained regulatory approval following such introduction into the market, and to make licensed products that have gained regulatory approval reasonably available to the public. The term of the agreements will continue until the expiration of the last to expire valid claim. The Company may terminate either of the license agreements without cause upon four months’ prior written notice to Harvard and Broad, unless terminated earlier. In February 2021, the Company provided written notice to Broad of its intent to terminate the Broad License Agreement, which termination was effective in June 2021. As partial consideration for the rights granted under the Harvard/ Broad License Agreement and Broad License Agreement, the Company paid $ 0.3 million in non-refundable upfront license fees and also issued 276,075 shares of its common stock with a fair value of $ 0.3 million. Additional consideration under the license agreements is as follows: Antidilution Rights —The initial shares of common stock issued to Harvard and Broad were subject to antidilution provisions. The antidilution rights associated with the Company achieving a defined aggregate level of preferred stock financing were partially satisfied in 2019 and fully satisfied in 2020, which settlement amounts totaled $ 0.1 million and $ 0.5 million, respectively, and which amounts were settled through issuances of 121,411 and 187,867 shares of common stock, respectively. The remaining antidilution rights obligation was fully satisfied in June 2021 upon the Company’s IPO. The settlement amount totaled $ 32.5 million and was settled through issuance of 878,098 shares of the Company's common stock. Success Payments —The Company is required to make success payments under the license agreements as further described in Note 5, Fair value of financial instruments. In September 2021, certain success payments were triggered and amounts due to Harvard and Broad totaled $ 6.3 million. These amounts were settled in cash in November 2021. Other Payments —The Company agreed to pay an annual license maintenance fee ranging from low-to-mid five figures to low six figures, depending on the particular calendar year, for the license agreements. The Company is responsible for the payment of certain patent prosecution and maintenance costs incurred by Harvard and Broad related to licensed patents. To the extent achieved, the Company is obligated to pay up to an aggregate of $ 46.2 million and $ 108 million in development and sales-based milestones, respectively. In 2022 , the first milestone was triggered and amounts due to Harvard and Broad totaled $ 0.3 million. These amounts were paid as of December 31, 2023. If the Company undergoes a change of control during the term of the license agreements, then certain of the milestone payments would be increased by a mid-double-digit percentage. To the extent there are sales of a licensed product, the Company is required to pay low single digit royalties on net sales, for each of the license agreements. The Company is entitled to certain reductions and offsets on these royalties with respect to a licensed product in a given country. Beam license agreement In April 2019, the Company and Beam Therapeutics, Inc. (“Beam”) entered into a collaboration and license agreement (the “Original Beam Agreement”), pursuant to which the Company received an exclusive, worldwide, sublicensable license under certain of Beam’s base editing technology, as well as gene editing and delivery technologies to develop, make, use, offer for sale, sell and import base editing products and nuclease products using Beam’s CRISPR associated protein 12b (“Cas12b technology”), in each case, directed to any of four gene targets, including the PCSK9 and ANGPTL3 genes, that are associated with an increased risk of coronary diseases (the “licensed products”). Upon execution of the Original Beam Agreement and as partial consideration for the rights granted to the Company thereunder, the Company issued 276,075 shares of its common stock to Beam. In July 2022, the Company and Beam amended and restated the Original Beam Agreement upon entering into the amended and restated collaboration and license agreement (the “ARCLA”). Pursuant to the ARCLA, Beam granted the Company an exclusive, worldwide, sublicensable license under certain of Beam’s base editing technology to develop and commercialize products directed towards a third liver-mediated, cardiovascular disease target, in addition to the PCSK9 and ANGPTL3 gene targets licensed under the Original Beam Agreement. The Company is responsible for the development and commercialization of products targeting the licensed gene targets, in each case subject to Beam’s opt-in right. Except as described below, the Company is fully responsible for the development of licensed products under the ARCLA. In October 2023, Beam and Eli Lilly and Company (“Lilly”) entered into the Transfer and Delegation Agreement (“TDA”), pursuant to which Lilly acquired certain rights previously held by Beam under the ARCLA. This included the right to opt-in to the Company’s PCSK9 and ANGPTL3 programs to share 33 % of worldwide development expenses and to jointly commercialize and share profits and expenses related to commercialization in the United States on a 50/50 basis. Additionally, for an undisclosed third cardiovascular disease gene target, Lilly acquired Beam’s right to opt-in to share 35 % of worldwide expenses of the development of such licensed product, as well as jointly commercialize and share 35 % of the profits and expenses of commercializing such licensed product worldwide. Under the ARCLA, the Company retains control of the development and commercialization of all collaboration products and holds all product rights for the PCSK9 and ANGPTL3 programs outside the United States. If Lilly exercises its opt-in right for a given licensed product (following such opt-in, a “collaboration product”), it will be obligated to pay for a specified percentage of the development and commercialization costs of such collaboration product and will have the right to receive a specified percentage of the profits from any sales of such collaboration product. With respect to each collaboration product, the Company and Lilly will enter into a subsequent co-promotion agreement prior to the anticipated sale of such collaboration product in the United States, pursuant to which the Company and Lilly will each provide 50 % of the promotional effort required to promote the collaboration product. For collaboration products, on a product-by-product basis outside of the United States, the Company is obligated to pay clinical and regulatory milestones of up to an aggregate of $ 5.6 million and sales-based milestones of up to an aggregate of $ 7.5 million. Due to the submission of the Company’s clinical trial application in New Zealand and the first patient dosing with VERVE-101 in a clinical trial, milestone payments of $ 0.3 million and $ 0.2 million, respectively, were triggered in 2022 and subsequently paid by the Company to Beam. Any licensed products for which Lilly has either (i) not elected to exercise its opt-in right or (ii) if Lilly has exercised its opt-in right, either the Company or Lilly subsequently elect to opt-out of the payment of shared development and commercialization costs and participating in the commercialization of such licensed product, are referred to as a “non-collaboration product.” For such non-collaboration products, on a product-by-product basis worldwide, the Company is obligated to pay clinical and regulatory milestones of up to an aggregate of $ 11.3 million and sales-based milestones of up to an aggregate of $ 15.0 million. To the extent there are sales of a collaboration product outside of the United States or a non-collaboration product worldwide, the Company will be required to pay tiered royalties to Lilly at rates ranging from the low-to-mid single digit percentage of net sales, subject to specified reductions. Such royalty payments will terminate on a country-by-country and product-by-product basis upon the later to occur of (i) the expiration of the last to expire valid claim under the patent rights covering such product in such country, (ii) the period of regulatory exclusivity associated with such product in such country or (iii) 10 years after the first commercial sale of such product in such country. The Company and Lilly each have the right to sublicense their respective licensed rights, subject to certain restrictions and provided that the sublicense agreement is in compliance and consistent with the terms of the ARCLA and any applicable licensed agreements. Under the ARCLA, the Company granted Beam an exclusive, worldwide, sublicensable, fully paid-up license under the Company’s intellectual property, including under the Company’s GalNAc-LNP delivery technology, relating to a preclinical program developed by the Company. Beam has a non-exclusive license under know-how and patents controlled by the Company, and an interest in joint collaboration technology, to allow Beam to conduct activities under agreed upon research and development plans, as applicable. The ARCLA granted Beam, on a target-by-target basis, the option to obtain a non-exclusive, worldwide, sublicensable license to the Company’s GalNAc-LNP delivery technology for the development and commercialization of certain base editor products, as to which Beam would owe the Company a fee upon exercise of each option, certain regulatory and commercial sale milestones as well as low single-digit royalties on net sales for base editor products using the GalNAc-LNP delivery technology. These rights remained with Beam and were not transferred to Lilly under the TDA. The Company concluded the receipt of any milestone or royalty payments under the ARCLA was not probable as of December 31, 2023. The term of the ARCLA continues until the last to expire of any royalty term for any licensed product. The Company has the right to terminate the ARCLA as to any licensed product, but not for any collaboration product, by delivering a 90-day termination notice to Lilly, provided that Lilly has elected not to exercise its opt-in right or the period to exercise such opt-in right has expired. Beam has the right to terminate the ARCLA as to certain products by delivering a 90-day termination notice to the Company. The ARCLA may be terminated by either party upon (i) written notice if the other party is in material breach and fails to cure such breach within the specified cure period or (ii) the other party’s bankruptcy or liquidation. Each party may terminate the licenses granted to it under the ARCLA immediately if the other party, directly or indirectly, challenges the enforceability, validity or scope of any patent rights underlying the licenses granted under the ARCLA. Acuitas agreements Development and option agreement In December 2019, the Company and Acuitas Therapeutics, Inc. ("Acuitas") entered into a development and collaboration agreement, which agreement was amended and restated in October 2020. The Company agreed to reimburse Acuitas on a quarterly basis for its services performed related to the program activities based on an agreed upon number of fulltime employees committed to work on the program at an annual rate per employee, including reimbursement of reasonable external costs. The Company did not recognize any research and development expense during the year ended December 31, 2023 related to the reimbursement of research and development services provided by Acuitas and technology maintenance fees. The Company recognized $ 0.1 million for the year ended December 31, 2022 related to the reimbursement of research and development services provided by Acuitas and technology maintenance fees. Under the terms of the agreement, the Company allowed the development and option agreement to terminate upon reaching the third anniversary of the agreement in December 2022. License agreement In October 2020, the Company paid Acuitas a non-refundable, upfront license fee of $ 2.0 million (less a previously paid target reservation fee) to exercise an option with respect to a licensed product and a licensed genome target and entered into a non-exclusive, worldwide license with Acuitas, with a right to sub-license through multiple tiers, under the licensed LNP technology to research, develop and commercialize the licensed products using the LNP technology in connection with the PCSK9 gene target for all human therapeutic or prophylactic uses. To the extent achieved, the Company is also obligated to pay up to an aggregate of $ 9.8 million in clinical and regulatory milestones and $ 9.5 million in sales-based milestones. D ue to the first patient dosing of VERVE-101 in a clinical trial, a milestone payment of $ 0.8 million was triggered and paid during the year ended December 31, 2022. No research and development expenses were recognized under the agreement in the year ended December 31, 2023. Novartis license agreement In October 2021, the Company entered into a license agreement with Novartis Pharma AG (“Novartis”) to obtain a non-exclusive license to lipid technology the Company is using in connection with the research and development of certain product candidates, including VERVE-102 and VERVE-201. As consideration for the license and rights granted under the agreement, the Company mad e a one-time, non-refundable, upfront payment of $ 0.8 million during the year ended December 31, 2021. The license agreement requires the Company to pay up to an aggregate of $ 10.0 million in clinical and regulatory milestones and $ 35.0 million in sales-based milestones for products that incorporate the licensed lipid technology. In 2023 , the first milestone was triggered and amounts due to Novartis totaled $ 0.5 million. These amounts were payable as of December 31, 2023 and will be settled in cash. In June 2022, the Company amended the agreement to include three additional licensed products to the scope of the non-exclusive license. In consideration of the additional licensed products, the Company was required to mak e a one-time, non-refundable upfront payment of $ 2.8 million to Novartis. This amount was recorded as research and development expense and was paid during the year ended December 31, 2022.

Collaboration and License Agree

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2023
Collaboration and License Agreements [Abstract]
Collaborative Arrangement Disclosure [Text Block]	9. Collaboration and license agreements Vertex agreement Summary of agreement In July 2022, the Company entered into a Strategic Collaboration and License Agreement (the “Vertex Agreement”) with Vertex Pharmaceuticals Incorporated (“Vertex”) for an exclusive, four-year worldwide research collaboration focused on developing in vivo gene editing candidates toward an undisclosed target for the treatment of a single liver disease. Additionally, in connection with the execution of the Vertex Agreement, the Company entered into a stock purchase agreement (the “Vertex Stock Purchase Agreement”) with Vertex, pursuant to which the Company sold 1,519,756 shares of its common stock to Vertex at a price of $ 23.03 per share, for an aggregate purchase price of $ 35.0 million. Pursuant to the Vertex Agreement, the Company is responsible for discovery, research and certain preclinical development of novel in vivo gene editing development candidates for the target of interest. The Company’s research activities are focused on (i) identifying and engineering specific gene editing systems and in vivo delivery systems directed to the target and (ii) evaluating and optimizing development candidates to achieve criteria specified in the Vertex Agreement. Vertex is obligated to reimburse the Company’s research expenses consistent with a mutually agreed-upon research plan and budget (“Vertex Research Plan”). The research term has an initial term of four years and may be extended by Vertex for up to one additional year (“Vertex Research Term”). The Vertex Research Plan is overseen by a Joint Research Committee (“Vertex JRC”) as detailed in the Vertex Agreement. Any material amendments to the Vertex Research Plan are required to be mutually agreed to by the Vertex JRC. During the Vertex Research Term, Vertex may select certain gene editing systems and in vivo delivery systems directed at the target to become a licensed agent. Upon the designation of the licensed agent, Vertex shall receive a license to exploit the licensed agent, and the licensed agent will continue to be developed under the Vertex Research Plan in order to achieve certain development candidate criteria agreed to by the Vertex JRC. Following the Vertex Research Term, Vertex will be solely responsible for subsequent development, manufacturing and commercialization of any product candidate resulting from the licensed agent. The Company received an upfront payment from Vertex of $ 25.0 million and is eligible to receive (i) success payments of up to $ 22.0 million for each product candidate (up to a maximum of $ 66.0 million) that achieves the applicable development criteria, (ii) up to an aggregate of $ 175.0 million in development milestones and (iii) up to an aggregate of $ 165.0 million in commercial milestone payments. The Company is also eligible to receive tiered single-digit royalties on net sales, with the rate dependent upon the type of product and subject to specified reductions. Such royalty payments will terminate on a country-by-country and product-by-product basis upon the later to occur of (i) the expiration of the last to expire valid claim under the patent rights covering such product in such country, (ii) the period of regulatory exclusivity associated with such product in such country or (iii) ten years after the first commercial sale of such product in such country. Prior to the first patient dosing in the first Phase 1b clinical trial for the first product candidate developed under the Vertex Agreement, the Company also has the right to opt-in to a profit share arrangement pursuant to which Vertex and the Company would share the costs and net profits for all product candidates emerging from the collaboration. If the Company exercises its opt-in right, in lieu of milestones and royalties, it will be obligated to pay for a specified percentage of the development and commercialization costs, and it will have the right to receive a specified percentage of the profits from any sales of any product candidates advanced under the collaboration. At the time the Company exercises the option, it may elect a profit/cost share of up to 40 % (with Vertex retaining a minimum of 60 %). In order to exercise its opt-in right, the Company is required to pay a fee depending on the profit/cost percentage elected by the Company and the Company’s licensed technology included in the most advanced product candidate at the time it exercises its opt-in right. Under all profit share scenarios, Vertex will control the worldwide development and commercialization of any product candidates resulting from the collaboration. The Vertex Agreement includes customary representations and warranties, covenants and indemnification obligations for a transaction of this nature. The Company and Vertex each have the right to terminate the agreement for material breach by, or insolvency of, the other party following notice, and if applicable, a cure period. Vertex may also terminate the Vertex Agreement in its entirety for convenience upon 90 days’ notice. Accounting Analysis The Company assessed the promised goods and services under the Vertex Agreement, in accordance with ASC 606. At inception, the Vertex Agreement included the following performance obligations: (i) the research services obligation which relates to the research and development services to be provided under the Vertex Research Plan (the “Initial Vertex Research Services”) and (ii) three licensed agent material rights related to the options to obtain licenses to exploit a licensed agent, at a discount. The Company identified $ 20.0 million of fixed transaction price consisting of the $ 25.0 million upfront fee offset by a discount of $ 5.0 million related to the 1,519,756 shares sold to Vertex under the Vertex Stock Purchase Agreement when measured at fair value on the date of issuance. The Company is also entitled to reimbursement of costs incurred associated with the delivery of services under the Vertex Research Plan. The Company utilized the most likely amount approach and estimated the expected cost reimbursement to be $ 5.8 million at inception. T he Company concluded that these amounts do not require a constraint and are included in the transaction price at inception. The Company considers this estimate at each reporting date and updates the estimate based on information available. Additional consideration to be paid to the Company upon reaching certain milestones are excluded from the transaction price as that consideration may only be earned subsequent to an option exercise The Company has concluded that the variable consideration related to the cost reimbursement of the Initial Vertex Research Services obligation will be allocated entirely to that obligation as the cost reimbursement relates specifically to the services being performed under the Vertex Research Plan. The reimbursement of the Initial Vertex Research Services is considered to be at a market rate and therefore depicts the estimated amount it would expect to receive for this obligation. As a result, the Company allocated the fixed consideration of $ 20.0 million to the three licensed agent material rights based on their relative standalone selling prices. The estimated standalone selling price for each material right was based on an adjusted market assessment approach. The Company concluded that the market would be willing to pay an equal amount for each licensed agent license on a standalone basis before being adjusted for the probability of the option becoming exercisable upon the successful completion of research activities to identify the licensed agents. The Company reached this conclusion after considering (i) the downstream economics including success fees, milestones and royalties related to each licensed agent being identical and (ii) all licensed agents are targeting the same gene. As such, based on the relative standalone selling price for each of the three material rights, the allocation of the transaction price to the separate performance obligations, at inception, is as follows : Performance obligation Amount (in thousands) Research services obligation $ 5,845 First licensed agent material right 6,667 Second licensed agent material right 6,667 Third licensed agent material right 6,666 Total $ 25,845 The amount allocated to the Initial Vertex Research Services obligation was recognized on a proportional performance basis over the period of service using input-based measurements of total cost of research incurred to estimate the proportion performed and remeasured at the end of each reporting period. The amount allocated to the licensed agent material rights was recorded as deferred revenue and will commence recognition upon exercise of each option or, if an option is never exercised, it will be recognized in full upon expiry of the Vertex Research Term . The Company classifies unexercised material rights as deferred revenue, net of current portion on the consolidated balance sheet as they are contingent upon successful development of licensed agents and at the option of the customer. When a material right is exercised, the amount allocated to the material right, which will be earned within the next twelve months, is reclassified to current deferred revenue. The reimbursement related to the Initial Vertex Research Servi ces was $ 5.4 million, based on the services rendered upon completion of the Initial Vertex Research Services as of June 30, 2023. Upon completion of the Initial Vertex Research Services, the parties agreed upon and estimated additional services to be rendered through December 31, 2024. The Company utilized the most likely amount approach and estimated the expected cost reimbursement to be $ 16.9 million which is being recognized on a proportional performance basis over the period of service using an input-based measurement. During the years ended December 31, 2023 and 2022, the Company recognized $ 8.5 million and $ 1.9 million , respectively, of revenue associated with the Vertex Agreement related to research services performed during the period. Costs incurred relating to the Company’s collaboration programs under the Vertex Agreement consist of internal and external research costs, which primarily include: salaries and benefits, and preclinical research studies. These costs are included in research and development expenses in the Company’s consolidated statements of operations during the year ended December 31, 2023 and December 31, 2022. Lilly agreement Summary of agreement In June 2023, the Company entered into a Research and Collaboration Agreement (the “Lilly Agreement”) with Lilly for an exclusive, five-year worldwide research collaboration initially focused on advancing the Company’s discovery-stage in vivo gene editing lipoprotein(a) program. On July 26, 2023, following expiration of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, the Lilly Agreement became effective. Additionally, in June 2023, in connection with the execution of the Lilly Agreement, the Company entered into a stock purchase agreement with Lilly (the “Lilly Stock Purchase Agreement”), pursuant to which the Company sold 1,552,795 shares of the Company's common stock to Lilly at a price of $ 19.32 per share for an aggregate purchase price of $ 30.0 million (the “Private Placement”). The Private Placement closed on July 31, 2023. Pursuant to the Lilly Agreement, the Company will be responsible for all research activities and Phase 1 clinical development of the initial target of interest— LPA . The Company’s research and development activities will be focused on (i) identifying and engineering specific gene editing systems and in vivo delivery technologies directed to the relevant target; (ii) evaluating and optimizing development candidates to achieve criteria specified in the Lilly Agreement; and (iii) Phase 1 clinical development ("Lilly Research Services"). Lilly will reimburse the Company’s research expenses and Phase 1 clinical development expenses consistent with an agreed-upon budget (“Lilly Research and Development Plan”). The research term for the initial target is five years and may be extended by Lilly for up to one additional year (“Lilly Research Term”). The Lilly Research and Development Plan is overseen by a Joint Steering Committee (“Lilly JSC”) as detailed in the Lilly Agreement. Any material amendments to the Lilly Research and Development Plan are required to be mutually agreed to by the Lilly JSC. A licensed product under the Lilly Agreement is an in vivo gene editing product that includes a candidate developed from the Lilly Research and Development Plan. A candidate is agreed upon when reviewed by the Lilly JSC against the candidate success criteria described in the Lilly Agreement. Upon approval of a candidate, Lilly will receive a license to exploit the licensed product, and the licensed product will continue to be developed under the Lilly Research and Development Plan through completion of the Phase 1 clinical trial for the applicable licensed product. Following completion of Phase 1 clinical trials with respect to any licensed product candidate under the Lilly Agreement, Lilly will be solely responsible for subsequent development, manufacturing and commercialization of each such product candidate resulting from the Company’s research efforts. Under the Lilly Agreement, the Company received an upfront payment from Lilly of $ 30.0 million in August 2023. The Company is also eligible to receive (i) up to an aggregate of $ 190.0 million in research and development milestone payments and (ii) up to an aggregate of $ 275.0 million in commercial milestone payments. The Company is also eligible to receive tiered and incremental high single and low-double digit royalties on global net sales, subject to specified reductions. Such royalty payments will terminate on a country-by-country and product-by-product basis upon the latest to occur of (i) the expiration of the last-to-expire valid claim under the patent rights covering such product in such country, (ii) expiration of the period of regulatory and market exclusivity associated with such product in such country or (iii) 10 years after the first commercial sale of such product in such country. Following completion of Phase 1 clinical development, the Company has the right to opt-in to a cost and margin share arrangement pursuant to which Lilly and the Company would share the costs and net margins for all product candidates emerging from the collaboration. If the Company exercises its opt-in right, the Company will be obligated to pay an opt-in fee in addition to funding 40 % of the development and commercialization costs, and it will have the right to receive, in lieu of the milestones and royalties described above, 40 % of the gross margin less eligible expenses from any sales of any product candidates advanced under the collaboration, with Lilly retaining 60 % of the cost and margin share. Notwithstanding this opt-in right, Lilly will control the worldwide development and commercialization of any product candidates resulting from the collaboration. Beyond the initial target of interest, upon the achievement of certain criteria and payment of additional upfront consideration, Lilly has the right to elect one additional, pre-determined target to the collaboration. The research, clinical development and commercialization of such additional target would be subject to the same terms under the Lilly Agreement as the initial target, including the Company’s right to receive up to an additional $ 465.0 million in research, development and commercial milestone payments, the Company’s right to receive tiered and incremental high single and low-double digit royalties on global net sales and the Company’s right to opt-in to a cost and margin share arrangement. During the Lilly Research Term, Lilly can make the determination subject to the terms of the Lilly Agreement, to replace the initial target or additional target with a different specified option target. Such replacement target will be the subject of a new licensed program under the research and development program. All rights granted with respect to the replaced target will cease upon Lilly’s election to select a different specified option target. The Lilly Agreement includes customary representations and warranties, covenants and indemnification obligations for a transaction of this nature. The Company and Lilly each have the right to terminate the agreement for material breach by the other party following notice, and if applicable, a cure period. Lilly may also terminate the Lilly Agreement in its entirety for convenience upon 180 days’ notice or in part, on a research plan, licensed target or product basis, for convenience upon 90 days’ notice. The Company may terminate the Lilly Agreement, in part with respect to its licensed patents, if Lilly directly or indirectly challenges the enforceability, validity or scope of such patent rights, or on a licensed product-by-licensed product basis, if such licensed product ceases to be developed for a period of time. Concurrently with the Lilly Agreement, the Company and Lilly entered into a Sublicense Option Agreement, pursuant to which the Company granted Lilly an option to obtain a non-exclusive sublicense under patent rights licensed to the Company under the Harvard/Broad License Agreement (“Lilly Option”). In consideration for the Lilly Option, Lilly paid the Company an upfront fee of $ 0.3 million . For accounting purposes, the upfront payments for the Lilly Agreement and the Sublicense Option Agreement will be combined. If Lilly exercises the Lilly Option, Lilly will be required to pay a sublicense fee to the Company and Lilly will reimburse the Company for royalties and milestones incurred related to the sublicensed product under the Harvard/Broad License Agreement. Accounting Analysis The Company assessed the promised goods and services under the Lilly Agreement, in accordance with ASC 606. At inception, the Lilly Agreement included the following performance obligations: (i) the Lilly Research Services obligation which relates to the research and development services to be provided under the Lilly Research and Development Plan and (ii) two licensed product material rights related to the right to obtain licenses to exploit a licensed product associated with the initial target upon achievement of certain development criteria. The Company identified $ 28.5 million of fixed transaction price consisting of (i) the $ 30.0 million upfront fee in the Lilly Agreement, (ii) the $ 0.3 million upfront fee in the Lilly Option, which is combined for accounting purposes, (iii) offset by a discount of $ 1.7 million related to the 1,552,795 shares sold to Lilly under the Lilly Stock Purchase Agreement when measured at fair value on the date of issuance. The Company is also entitled to reimbursement of costs incurred associated with the delivery of the Lilly Research Services. The Company utilized the most likely amount approach and estimated the expected cost reimbursement to be $ 16.4 million at inception, which represents the budget for the first year of the Lilly Research Services. The remainder of the Lilly Research and Development Plan budget is subject to annual review by Lilly and the Company. The Company concluded that these amounts do not require a constraint and are included in the transaction price at inception. The Company considers this estimate at each reporting date and updates the estimate based on information available. Additional consideration to be paid to the Company upon reaching certain milestones are excluded from the transaction price at contract inception as they are not probable at this time. The probability will be re-evaluated each reporting period, and the transaction price will be updated accordingly. The Company has concluded that the variable consideration related to the cost reimbursement of the Lilly Research Services obligation will be allocated entirely to that obligation as the cost reimbursement relates specifically to the services being performed under the Research and Development Plan. The reimbursement of the Research and Development Services is considered to be at a market rate and therefore depicts the estimated amount it would expect to receive for this obligation. As a result, the Company allocated the fixed consideration of $ 28.5 million to the two licensed product material rights based on their relative standalone selling prices. The estimated standalone selling price for each material right was based on an adjusted market assessment approach. The Company concluded that the market would be willing to pay an equal amount for each license on a standalone basis before being adjusted for the probability of the option becoming exercisable upon the successful completion of research and development activities to identify the licensed products. The Company reached this conclusion after considering (i) the downstream economics including success fees, milestones and royalties related to each licensed product being identical and (ii) both licensed products are targeting the same gene. As such, based on the relative standalone selling price for each of the material rights, the allocation of the transaction price to the separate performance obligations, at inception, is as follows: Performance obligation Amount (in thousands) Research services obligation $ 16,398 First licensed product material right 14,270 Second licensed product material right 14,270 Total $ 44,938 The amount allocated to the Lilly Research Services obligation is being recognized on a proportional performance basis over the period of service using input-based measurements of total cost of research incurred to estimate the proportion performed and remeasured at the end of each reporting period. The amount allocated to the licensed product material rights was recorded as deferred revenue and will commence recognition upon the achievement of the candidate selection criteria or, if never achieved, it will be recognized in full upon expiry of the Lilly Research Term. The Company classifies unexercised material rights as deferred revenue, net of current portion on the consolidated balance sheet as they are contingent upon the successful development and achievement of development criteria. When a material right is exercised, the amount allocated to the material right, which will be earned within the next twelve months, is reclassified to current deferred revenue. During the year ended December 31, 2023, the Company recognized $ 3.2 million of revenue associated with the Lilly Agreement related to the Lilly Research Services performed during the period. As of December 31, 2023, the Company has recorded $ 28.5 million as non-current deferred revenue related to the unexercised material rights. Costs incurred relating to the Company’s collaboration programs under the Lilly Agreement consist of internal and external research costs, which primarily include: salaries and benefits, and preclinical research studies. These costs are included in research and development expenses in the Company’s consolidated statements of operations during the year ended December 31, 2023 .

Preferred and Common Stock

Preferred and Common Stock	12 Months Ended
	Dec. 31, 2023
Preferred Stock [Abstract]
Preferred and Common Stock	10. Preferred and common stock The Company has issued and sold 101,170,571 Series A preferred, 7,838,461 Series A-2 preferred, and 77,163,022 Series B preferred and common stock. In June 2021, the Company amended and restated its certificate of incorporation to authorize 5,000,000 shares of preferred stock, which shares of preferred stock are currently undesignated, and 200,000,000 shares of common stock, $ 0.001 par value per share. In June 2021, the Company completed its IPO, pursuant to which the Company issued and sold 16,141,157 shares of its common stock, including 2,105,368 shares of its common stock sold pursuant to the full exercise of the underwriters' option to purchase additional shares, at a public offering price of $ 19.00 per share, for aggregate gross proceeds of $ 306.7 million. The Company received approximately $ 281.6 million in net proceeds, after deducting underwriting discounts and offering expenses payable by the Company. Upon the closing of the IPO, all outstanding shares of the Company's preferred stock automatically converted into 27,720,923 shares of the Company's common stock, and the Company issued 878,098 shares of its common stock to Harvard and Broad as final settlement of its antidilution rights obligation. In July 2022, in connection with the execution of the Vertex Agreement, the Company and Vertex also entered into the Stock Purchase Agreement for the sale and issuance of 1,519,756 shares of the Company’s common stock to Vertex at a price of $ 23.03 per share, for an aggregate purchase price of $ 35.0 million. In July 2022, the Company completed a follow-on public offering of common stock, pursuant to which the Company issued and sold 9,583,334 shares of its common stock, including 1,250,000 shares of its common stock sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a public offering price of $ 27.00 per share. The Company received net proceeds of approximately $ 242.9 million after deducting underwriting discounts and offering expenses of approximately $ 15.8 million. In July 2022, the Company entered into an Open Market Sale Agreement (the “Sales Agreement”) with Jefferies LLC (“Jefferies”) as the agent pursuant to which the Company is entitled to offer and sell, from time to time at prevailing market prices, shares of the Company’s common stock. The Company agreed to pay Jefferies a commission of up to 3.0 % of the aggregate gross sale proceeds of any shares sold by Jefferies under the Sales Agreement. As of December 31, 2023, the Company sold 2,780,853 shares of its common stock under the Sales Agreement for aggregate net proceeds of $ 63.5 million, after deducting commissions and offering expenses payable by the Company. The Company sold an additional 1,766,835 shares of its common stock under the Sales Agreement for aggregate net proceeds of $ 22.5 million subsequent to December 31, 2023. In July 2023, in connection with the execution of the Lilly Agreement, the Company and Lilly also entered into the Lilly Stock Purchase Agreement, pursuant to which the Company sold 1,552,795 shares of common stock to Lilly at a price of $ 19.32 per share, for an aggregate purchase price of $ 30.0 million . In December 2023, the Co mpany completed a follow-on public offering of common stock, pursuant to which the Company issued and sold 14,375,000 shares of its common stock, including 1,875,000 shares of its common stock sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a public offering price of $ 10.00 per share. The Company received net proceeds of approximately $ 134.7 million after deducting underwriting discounts and offering expenses of approximately $ 9.0 million . In December 2023, the Company also completed a private placement pursuant to a stock purchase agreement with Lilly for the sale and issuance of 2,296,317 shares of common stock at a purchase price of $ 10.00 per share for an aggregate purchase price of $ 23.0 million . The holders of c ommon stock are entitled to one vote for each share of common stock.

Stock-based compensation

Stock-based compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-based compensation	11. Stock-based compensation The 2018 Equity Incentive Plan (the “2018 Plan”), adopted by the board of directors in August 2018 provided for the grant of qualified incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock and restricted stock units to the Company’s employees, officers, directors, advisors, and outside consultants for the issuance or purchase of shares of the Company’s common stock. The maximum number of shares of common stock that were authorized for issuance under the 2018 Plan was 6,885,653 . In June 2021, the Company's board of directors adopted, and the Company's stockholders approved, the 2021 Stock Incentive Plan (the “2021 Plan”), which became effective on June 16, 2021. The 2021 Plan provides for grant of qualified and nonqualified stock options, stock appreciation rights, restricted and unrestricted stock and stock units, performance awards, and other share-based awards to the Company's employees, directors, advisors and outside consultants. The shares reserved for issuance pursuant to the 2021 Plan are subject to an annual increase through January 1, 2031. As of December 31, 2023 the Company had reserved 10,144,170 shares of the Company's common stock for issuance of stock options, restricted stock, and restricted stock units, of which 3,123,972 remained outstanding for future grant under the 2021 Plan. On January 1, 2024, 4,098,485 shares of the Company's common stock were added to the amount reserved for issuance under the 2021 Plan. Upon effectiveness of the 2021 Plan, the Company ceased granting additional awards under the 2018 Plan. Stock-based compensation expense recorded in the consolidated statements of operations and comprehensive loss is as follows: Year ended (in thousands) 2023 2022 2021 Research and development $ 19,125 $ 12,486 $ 3,830 General and administrative 15,991 9,991 3,242 Total stock-based compensation expense $ 35,116 $ 22,477 $ 7,072 Stock options The assumptions used in Black-Scholes for stock options granted were as follows: Year ended 2023 2022 2021 Expected volatility 77.7 % 77.3 % 77.7 % Weighted-average risk-free interest rate 4.0 % 2.4 % 0.9 % Expected dividend yield — — — Expected term (in years) 6.0 6.0 6.0 The following table provides a summary of stock option activity during the year ended December 31, 2023: Number of Weighted Weighted Aggregate (2) Outstanding at December 31, 2022 7,612,826 $ 16.10 Granted 3,152,042 19.83 Exercised ( 240,182 ) 5.00 Forfeited ( 599,808 ) 25.57 Outstanding at December 31, 2023 9,924,878 $ 16.98 7.8 $ 36,695 Exercisable at December 31, 2023 4,549,532 $ 12.49 6.9 $ 29,820 Expected to vest after December 31, 2023 (1) 5,375,346 $ 20.79 8.6 $ 6,875 (1) This represents the number of unvested options outstanding as of December 31, 2023 that are expected to vest in the future. (2) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the common stock for the options that were in the money as of December 31, 2023 . During the year ended December 31, 2023, the weighted average grant date fair value of the stock options granted was $ 19.83 per share. The aggregate intrinsic value of stock options exercised during the year ended December 31, 2023 was approximately $ 2.8 million while the Company received $ 1.2 million in proceeds for the exercise of these options. As of December 31, 2023, there was $ 68.8 million of unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted-average period of approximately 2.4 years. Restricted stock and restricted stock units In 2018, the Company issued 2,150,537 shares of restricted common stock. The restricted shares vested in 48 equal monthly installments, commencing on January 1, 2018. The restricted shares were fully vested as of December 31, 2021. During the year ended December 31, 2023, the Company granted 572,140 restricted stock units under the 2021 Plan. These restricted stock units vest in substantially equal installments over a four-year period. A summary of the status of and change in unvested restricted stock units as of December 31, 2023 was as follows: Shares Weighted- Unvested restricted stock units as of December 31, 2022 677,825 $ 23.10 Restricted stock units granted 572,140 $ 17.76 Restricted stock units vested ( 149,456 ) $ 22.58 Restricted stock units forfeited ( 135,998 ) $ 23.74 Unvested restricted stock units as of December 31, 2023 964,511 $ 19.92 At December 31, 2023, there was $ 16.1 million of unrecognized stock-based compensation expense related to restricted stock units that are expected to vest. These costs are expected to be recognized over a weighted-average remaining vesting period of 3.1 years. 2021 Amended and Restated Employee Stock Purchase Plan In June 2021, the board of directors adopted, and the Company's stockholders approved, the 2021 Employee Stock Purchase Plan (the "ESPP"), as amended and restated, which became effective on June 16, 2021. The shares reserved for issuance pursuant to the ESPP are subject to an annual increase through January 1, 2031. As of December 31, 2023, 258,549 shares had been purchased by employees under the ESPP and 1,277,192 shares remained available for issuance under the ESPP. On January 1, 2024, 819,697 shares of common stock were added to the amount reserved for sale under the ESPP.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	12. Net loss per share The following table summarizes the computation of basic and diluted net loss per share: Year ended December 31, (in thousands, except share and per share amounts) 2023 2022 2021 Numerator: Net loss $ ( 200,068 ) $ ( 157,387 ) $ ( 120,314 ) Denominator: Weighted average number of common shares, basic and diluted 64,175,137 54,023,653 26,872,036 Net loss per common share, basic and diluted $ ( 3.12 ) $ ( 2.91 ) $ ( 4.48 ) The Company’s potential dilutive securities, which include, unvested restricted stock, unvested restricted stock units, and common stock options, have been excluded from the computation of diluted net loss per share as the effects would be anti-dilutive. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at period end, from the computation of diluted net loss per share for the period indicated because including them would have had an anti-dilutive effect: Year ended December 31, 2023 2022 2021 Unvested restricted stock units 964,511 677,825 32,000 Outstanding options to purchase common stock 9,924,878 7,612,826 6,119,295 Total 10,889,389 8,290,651 6,151,295

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	13. Income taxes The Company's losses before income taxes consist solely of losses from domestic operations, which totaled $ 199.8 million , $ 157.3 million and $ 120.3 million for the years ended December 31, 2023, 2022, and 2021, respectively. Income tax expense (benefit) is summarized as follows: Year ended December 31, (in thousands) 2023 2022 2021 Current: Federal $ - $ - $ - State 275 53 - Foreign - - - Total current provision $ 275 $ 53 $ - Deferred: Federal - - - State - - - Foreign - - - Total deferred provision $ - $ - $ - A reconciliation of the income tax expense computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year ended December 31, (in thousands) 2023 2022 2021 Federal statutory rate 21.0 % 21.0 % 21.0 % Change in valuation allowance ( 31.3 )% ( 34.7 )% ( 31.3 )% Stock-based compensation ( 1.0 )% ( 0.3 )% 0.9 % Executive compensation ( 0.2 )% ( 0.8 )% ( 1.1 )% Permanent items ( 0.1 )% ( 0.2 )% ( 0.1 )% State income taxes, net of federal benefit 8.2 % 8.4 % 6.1 % Research and development tax credits 3.6 % 5.6 % 4.5 % Other ( 0.3 )% 1.0 % 0.0 % Effective income tax rate ( 0.1 )% — % — % Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022 are comprised of the following : December 31, (in thousands) 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 51,295 $ 43,779 Capitalized costs—net of amortization 10,844 11,095 Research and development tax credits 31,220 20,835 Capitalized research costs 64,255 28,650 Deferred revenue 5,525 77 Stock-based compensation 8,926 3,669 Other 134 97 Lease liability 20,646 22,285 Accrued expenses 3,726 5,024 Total deferred tax assets 196,571 135,511 Deferred tax liabilities: Property and equipment ( 1,207 ) ( 881 ) Right of use asset ( 23,254 ) ( 24,994 ) Total deferred tax liabilities ( 24,461 ) ( 25,875 ) Total deferred tax assets, net 172,110 109,636 Less: valuation allowance ( 172,110 ) ( 109,636 ) Deferred tax assets, net of valuation allowance $ — $ — The Company has incurred net operating losses in each year since inception. Management has evaluated the positive and negative evidence bearing upon the realizability of the Company’s net deferred tax assets, which are comprised primarily of net operating loss carryforwards, tax credits, and costs capitalized for tax purposes. Management has considered the Company’s history of cumulative net losses in the United States and estimated future tax losses and has determined that it is more likely than not that the Company will not recognize the benefits of the net deferred tax assets. As a result, the Company has recorded a full valuation allowance at December 31, 2023 and 2022. The valuation allowance increased by $ 62.5 million in 2023, due to the increase in deferred tax assets, primarily due to net operating loss carryforwards, tax credit carryforwards, and increase in deferred tax assets associated with current year temporary items. Realization of the future tax benefits is dependent on many factors, including the Company’s ability to generate taxable income within the net operating loss carryforward period. The Company’s ability to utilize these federal and state net operating loss and research and development credit carryforwards may be limited in the future if the Company experiences an ownership change pursuant to Internal Revenue Code 382. An ownership change occurs when the ownership percentages of 5% or greater shareholders change by more than 50% over a three-year period. As of December 31, 2023, the Company has not completed a study to assess whether a change of control has occurred and whether the net operating losses and credits are limited due to a change in ownership. To the extent that an assessment is completed in the future, the Company’s ability to utilize tax attributes could be restricted on a year-by-year basis and certain attributes could expire before they are utilized. As of December 31, 2023, the Company had approximately $ 188.2 million of federal and $ 186.1 million of state net operating loss carryforwards. The federal net operating losses have an indefinite life and can be utilized to offset 80 % of future taxable income, while the state net operating losses will start to expire from 2038 through 2043 . Additionally, as of December 31, 2023, the Company had approximately $ 20.9 million of federal tax credits that expire from 2039 to 2043 . The Company had $ 13.1 million of Massachusetts research and development tax credits and Massachusetts investment tax credits that expire starting in 2035 and 2024 , respectively. As of December 31, 2023 and 2022 , the Company had no uncertain tax positions. The Company recognizes both interest and penalties associated with unrecognized tax benefits as a component of income tax expense. The Company has no t recorded any interest or penalties for unrecognized tax benefits since its inception. The Company files income tax returns in the United States, California, Connecticut, the Commonwealth of Massachusetts, Pennsylvania, Wisconsin and various other state jurisdictions. The Company is not currently under examination by the Internal Revenue Service or any other jurisdiction. All tax years remain open to tax examination. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may be adjusted upon examination by the Internal Revenue Service or state tax authorities to the extent utilized in a future period.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	14. Related party transactions An executive officer of Beam was a board member of the Company until August 2022. In October 2020, the Company and Beam entered into a materials exchange agreement wherein the parties agreed that Beam would provide certain mRNA, gRNA, and protein to the Company and that the Company would provide certain gRNAs to Beam at an agreed upon price per each material provided. For the year ended December 31, 2022, the Company recognized $ 0.4 million as a reduction to research and development expense related to reimbursements received for materials sold to Beam. The Company did not recognize any reduction to research and development expense related to reimbursements received for materials sold to Beam in the year ended December 31, 2023. In December 2021, the Company entered into a sublease agreement with Beam for laboratory and office space in Cambridge, Massachusetts, which sublease terminated in December 31, 2022. Total rent payments under this sublease were $ 1.8 million for the year ended December 31, 2022.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefit Plans	15. Employee benefit plans The Company has a defined-contribution plan established under Section 401(k) of the Internal Revenue Code (the “401(k) Plan”), which covers substantially all employees. Employees are eligible to participate in the 401(k) Plan beginning on the first day of employment. The 401(k) Plan includes a salary deferral arrangement pursuant to which participants may elect to reduce their current compensation by up to the sta tutorily prescribed limit, equal to $ 22,500 in 2023 with a catch up contribution limit equal to $ 7,500 for those 50 years of age or older, and have the amount of the reduction contributed to the 401(k) Plan. Since January 1, 2020 the Company matches 100 % of each participant’s annual contribution to the 401(k) plan up to 3 % of the participant’s salary and then 50 % of each participant’s contribution up to 2 % of the participant’s salary. The match immediately vests 100 %. The matching c ontributions by the Company to the 401(k) plan were $ 1.5 million, $ 1.0 million and $ 0.4 million for the years ended December 31, 2023, 2022, and 2021 , respectively.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	16. S ubsequent events On February 14, 2024, the Company's board of directors adopted the 2024 Inducement Stock Incentive Plan (the “Inducement Plan”). The Inducement Plan provides for the grant of non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards to persons who (a) were not previously an employee or director or (b) are commencing employment with the Company following a bona fide period of non-employment, in either case, as an inducement material to such person’s entry into employment with the Company and in accordance with the requirements of the Nasdaq Stock Market Rule 5635(c)(4). As of February 27, 2024, the maximum number of shares of the Company’s common stock reserved for issuance under the Inducement Plan is 4,000,000 shares. There are no other material recognized or unrecognized subsequent events requiring disclosure, other than as indicated in Note 10, "Preferred and common stock", with respect to sales of the Company's shares of common stock under the Sales Agreement with Jefferies.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Principles of Consolidation	Principles of consolidation The accompanying consolidated financial statements include the accounts of Verve and its wholly owned subsidiary, Verve Securities Corporation. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities as of and during the reporting period. The Company bases its estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances.
Cash and Cash Equivalents	Cash and cash equivalents Cash and cash equivalents consist of standard checking accounts and money market account funds that invest primarily in U.S. government-backed securities and treasuries. The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents are stated at cost, which is substantially equivalent to fair value.
Restricted cash	Restricted cash Restricted cash represents collateral provided for a letter of credit issued as a security deposit in connection with the Company’s leases of its corporate facilities. A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: December 31, (in thousands) 2023 2022 Cash and cash equivalents $ 206,180 $ 115,412 Restricted cash 4,774 4,824 Total cash, cash equivalents and restricted cash $ 210,954 $ 120,236
Marketable Securities	Marketable securities The Company classifies marketable securities with a remaining maturity when purchased of greater than three months as available-for-sale. Available-for-sale securities are maintained by the Company’s investment managers and consist of U.S. treasury bills and U.S agency securities. The Company classifies investments available to fund current operations as current assets on its consolidated balance sheets. Available-for-sale securities are carried at fair value with the unrealized gains and losses included in accumulated other comprehensive income (loss) as a component of stockholders’ equity until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income and/or expense over the life of the instrument. Realized gains and losses are determined using the specific identification method and are included in other income (expense). Marketable securities are evaluated for impairment at the end of each reporting period. Impairment is evaluated considering numerous factors, and their relative significance varies depending on the situation. Factors considered include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospects of the issuer, and the Company's intent and ability to hold the investment to allow for an anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit- related is recognized in other comprehensive (loss) income, net of applicable taxes.
Concentration of Credit Risk	Concentrations of credit risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash, cash equivalents, marketable securities, collaboration receivable, and restricted cash. Periodically, the Company may maintain deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality, and the Company has not experienced any losses on these deposits. The Company generally invests its excess capital in money market funds, U.S. treasury bills and agency securities, all of which are subject to minimal credit and market risk. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer.
Deferred Offering Costs	Deferred offering costs The Company capitalized incremental legal, professional accounting and other third-party fees that were directly associated with the stock offerings as other non-current assets until the offerings were consummated. After consummation of the offerings, these costs were recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering.
Fair Value of Financial Instruments	Fair value of financial instruments ASC Topic 820, Fair Value Measurement (“ASC 820”), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the assets or liability and are developed based on the best information available in the circumstances. ASC 820 identifies fair value as the price that would be received to sell an asset or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tiered value hierarchy that distinguishes between the following: Level 1—Quoted market prices in active markets for identical assets or liabilities. Level 2—Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Level 3—Unobservable inputs for the asset or liability (i.e. supported by little or no market activity). Level 3 inputs include management’s own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk). To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. There have been no changes to the valuation methods utilized by the Company during the years ended December 31, 2023, 2022 and 2021. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of financial instruments between levels during the years ended December 31, 2023 and 2022 .
Property and Equipment, Net	Property and equipment, net Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset as follows: Asset category Estimated useful life Computer equipment and software 3 years Office furniture 4 years Laboratory equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are charged to expense as incurred.
Impairment of Long-Lived Assets	Impairment of long-lived assets The Company evaluates its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. There were no impairment losses recognized during the years ended December 31, 2023, 2022 and 2021 .
Freestanding Financial Instruments and Derivatives	Freestanding financial instruments and derivatives The Company has identified the following financial instruments, which are recorded as liabilities in the balance sheet and separately accounted for at fair value. Pursuant to license agreements with (i) the President and Fellows of Harvard College (“Harvard”) and The Broad Institute, Inc. (“Broad”) (“Harvard/Broad License Agreement”) and (ii) Broad (“Broad License Agreement”) (see Note 8, License agreements), the following financial instruments were issued by the Company. Antidilution Rights —The antidilution rights represented the obligation to issue additional shares of common stock to Harvard and Broad following the completion of additional financings, including the Company’s initial public offering. These antidilution rights were accounted for under ASC 815, Derivatives and Hedging ("ASC 815") , and were initially recorded at fair value with a corresponding charge to research and development expense. The liability was remeasured at each reporting period, with changes in fair value recognized in other income (expense) in the statement of operations and comprehensive loss while this instrument was outstanding. The obligation was satisfied in full upon the issuance of an aggregate of an additional 878,098 shares of common stock upon the closing of the Company's initital public offering ("IPO") in June 2021. Success Payments —The Company is obligated to pay to Harvard and Broad tiered success payments in the event the Company’s average market capitalization exceeds specified thresholds ascending from a mid ten-digit dollar amount to $ 10.0 billion, or sale of the Company for consideration in excess of those thresholds. In the event of a change of control of the Company or a sale of the Company, the Company is required to pay in cash within a specified period following such event. Otherwise, the payments may be settled at the Company’s option in either cash or shares of the Company’s common stock. The success payments are accounted for under ASC 815 and were initially recorded at fair value with a corresponding charge to research and development expense. The liability is remeasured at each reporting period with all changes in value recognized in other income (expense) in the statement of operations and other comprehensive loss. During the year ended December 31, 2021, certain success payment obligations were triggered, and amounts paid to Harvard and Broad totaled $ 6.3 million. These amounts were settled in cash in November 2021. No success payments were triggered or paid during the years ended December 31, 2023 and 2022. The Company will continue to adjust the liability for changes in fair value until the earlier of the achievement or expiration of the remaining success payment obligation. Refer to Note 5, Fair value of financial instruments, for additional discussion .
Revenue Recognition	Revenue Recognition The Company enters into collaboration agreements which are within the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), under which the Company licenses rights to certain of the Company’s product candidates and performs research and development services. The terms of these arrangements typically include payment of one or more of the following: non-refundable, upfront fees; reimbursement of research and development costs; development, regulatory, and commercial milestone payments; and royalties on net sales of licensed products. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine the appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, the Company performs the following five steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect consideration it is entitled to in exchange for the goods or services it transfers to the customer. The promised goods or services in the Company’s arrangements typically consist of license rights to the Company’s intellectual property and research and development services. The Company provides options to additional items in the contracts, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. The Company evaluates the customer options for material rights, or options to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. Performance obligations are promised goods or services in a contract to transfer a distinct good or service to the customer and are considered distinct when (i) the customer can benefit from the good or service on its own or together with other readily available resources and (ii) the promised good or service is separately identifiable from other promises in the contract. In assessing whether promised goods or services are distinct, the Company considers factors such as the stage of development of the underlying intellectual property, the capabilities of the customer to develop the intellectual property on its own or whether the required expertise is readily available and whether the goods or services are integral or dependent to other goods or services in the contract. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the number of potential payments and the likelihood that the payments will be received. The Company utilizes either the most likely amount method or expected amount method to estimate the amount expected to be received based on which method best predicts the amount expected to be received. The amount of variable consideration which is included in the transaction price may be constrained and is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. The Company’s contracts often include development and regulatory milestone payments which are assessed under the most likely amount method and constrained if it is probable that a significant revenue reversal would occur. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenues in the period of adjustment. To date, the Company has not recognized any consideration related to the achievement of development, regulatory, or commercial milestone revenue resulting from any of the Company’s collaboration arrangements. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any consideration related to sales-based royalty revenue resulting from any of the Company’s collaboration arrangements. The Company allocates the transaction price based on the estimated stand-alone selling price of each of the performance obligations. The Company must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. The Company utilizes key assumptions to determine the stand-alone selling price for service obligations, which may include other comparable transactions, pricing considered in negotiating the transaction and the estimated costs. Additionally, in determining the standalone selling price for material rights, the Company utilizes comparable transactions, clinical trial success probabilities, and estimates of option exercise likelihood. Variable consideration is allocated specifically to one or more performance obligations in a contract when the terms of the variable consideration relate to the satisfaction of the performance obligation and the resulting amounts allocated are consistent with the amounts the Company would expect to receive for the satisfaction of each performance obligation. The consideration allocated to each performance obligation is recognized as revenue when control is transferred for the related goods or services. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Upfront payments and fees are recorded as deferred revenue upon receipt or when due until the Company performs its obligations under these arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional.
Research and Development Costs	Research and development costs Research and development costs are charged to expense as incurred. Research and development costs consist of costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, third-party license fees related to technology with no alternative future use, laboratory supplies, depreciation, manufacturing expenses, preclinical, clinical and regulatory expenses, consulting and other contracted services. Costs for certain research and development activities are recognized based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the financial statements as prepaid or accrued research and development.
Stock-Based Compensation	Stock-based compensation The Company’s stock-based compensation program allows for grants of certain equity awards. Grants are awarded to employees and non-employees, including directors. The Company accounts for its stock-based compensation in accordance with ASC Topic 718, Compensation-Stock Compensation (‘‘ASC 718’’). ASC 718 requires all stock-based payments to employees, non-employees and directors, to be recognized as expense in the consolidated statements of operations and comprehensive loss based on their grant date fair values. The Company estimates the fair value of options granted using the Black-Scholes option pricing model (‘‘Black-Scholes’’) for stock option grants to both employees and non-employees. The fair value of the Company’s common stock is used to determine the fair value of restricted stock unit awards. The Company estimates the fair value of the Company’s restricted stock unit awards on the date of grant using the closing price of the Company’s common stock on that date. The Company’s stock-based compensation awards are subject to either service or performance-based vesting conditions. Compensation expense related to awards to employees, directors and non-employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards to employees with performance-based vesting conditions is recognized over the implied service period when achievement of the performance-based milestones is deemed probable. The Company uses judgment to determine whether and, if so, how many awards are deemed probable of vesting at each reporting period. The estimation of fair value for stock-based compensation requires management to make estimates and judgments about, among other things, the estimated life of options and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized. Prior to the Company's IPO in June 2021, there was no public market for its common stock. As a result, prior to the IPO, the estimated fair value of the Company's common stock was determined by its board of directors as of the date of each option grant, with input from management, considering the Company's most recently available third-party valuations of common stock and its board of directors' assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the date of grant. Following the Company's IPO, the fair value of its common stock is determined based on the closing price of the Company's common stock as reported on the Nasdaq Global Select Market .
Leases	Leases The Company accounts for leases in accordance with ASC Topic 842 Leases ("ASC 842"). At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on specific facts and circumstances, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. If an arrangement is determined to be or contain a lease, the lease is assessed for classification as either an operating or finance lease at the lease commencement date, defined as the date on which the leased asset is made available for use by the Company, based on the economic characteristics of the lease. The lease liability is measured at the present value of future lease payments, discounted using the discount rate as of the lease commencement date. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the incremental borrowing rate, which is the rate incurred to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company recognizes a corresponding lease right of use (“ROU”) asset, initially measured as the amount of lease liability, adjusted for any initial lease costs or lease payments made before or at the commencement of the lease, and reduced by any lease incentives. The Company’s leases consist of only operating leases. Operating leases are recognized on the balance sheet as ROU lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while certain variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis.
Income Taxes	Income taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the Company’s financial statements and tax returns. Deferred tax assets and liabilities are determined based upon the differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities and for loss and credit carryforwards, using enacted tax rates expected to be in effect in the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that these assets may not be realized. The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more-likely-than-not recognition threshold is calculated as the largest amount that is more than 50 % likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes.
Comprehensive Loss	Comprehensive loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2023, 2022 and 2021, the Company’s only element of other comprehensive loss was unrealized gains and losses on marketable securities.
Net Loss Per Share	Net loss per share The Company follows the two-class method when computing net loss per share, as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding for the period. Diluted net loss is computed by adjusting net loss to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share is computed by dividing the diluted net loss by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents. In periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported a net loss for the years ended December 31, 2023, 2022 and 2021 .
Segment and Geographic Information	Segment and geographic information Operating segments are defined as components of an entity about which separate discrete information is available for evaluation by the chief operating decision maker (“CODM”), or decision-making group, in deciding how to allocate resources and in assessing performance. The CODM is the Company’s Chief Executive Officer. The Company views its operations as and manages its business in one operating segment operating exclusively in the United States.
Subsequent Events	Subsequent events The Company performs an evaluation of all subsequent events after the balance sheet date through the date of issuance of the consolidated financial statements to ensure appropriate disclosure of events both recognized in the consolidated financial statements and events which occurred subsequently but were not recognized in the consolidated financial statements.
Recently adopted accounting pronouncements	Recently adopted accounting pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that was previously used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, this standard requires allowances to be recorded instead of reducing the amortized cost of the investment. The new standard became effective for the Company on January 1, 2023. Based on the Company’s analysis, the adoption of this standard did not have a material impact on the Company’s financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Reconciliation of Cash, Cash Equivalents and Restricted Cash	A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: December 31, (in thousands) 2023 2022 Cash and cash equivalents $ 206,180 $ 115,412 Restricted cash 4,774 4,824 Total cash, cash equivalents and restricted cash $ 210,954 $ 120,236
Schedule of Property and Equipment Estimated Useful Life	Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset as follows: Asset category Estimated useful life Computer equipment and software 3 years Office furniture 4 years Laboratory equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Marketable Securities	Marketable securities by security type consisted of the following: December 31, 2023 (in thousands) Amortized Gross Gross Fair U.S. treasury bills and notes $ 147,978 $ 144 $ ( 15 ) $ 148,107 U.S. agency securities 269,520 277 ( 134 ) 269,663 Total $ 417,498 $ 421 $ ( 149 ) $ 417,770 December 31, 2022 (in thousands) Amortized Gross Gross Fair U.S. treasury bills and notes $ 228,432 $ 13 $ ( 301 ) $ 228,144 U.S. agency securities 211,658 68 ( 474 ) 211,252 Total $ 440,090 $ 81 $ ( 775 ) $ 439,396 The remaining contractual maturities of all marketable securities were less than 24 months as of December 31, 2023 and 2022 .

Property and equipment, net (Ta

Property and equipment, net (Table)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, net	Property and equipment, net, consisted of the following: December 31, (in thousands) 2023 2022 Lab equipment 28,851 20,379 Leasehold improvements 726 266 Furniture and fixtures 2,323 2,294 Computer equipment 997 826 Total property and equipment 32,897 23,765 Less accumulated depreciation ( 10,392 ) ( 4,987 ) Property and equipment, net $ 22,505 $ 18,778
Schedule of Depreciation Expense	Year ended December 31, (in thousands) 2023 2022 2021 Depreciation expense $ 5,455 $ 2,804 $ 1,535

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Instruments, Assets and Liabilities	The following tables set forth the fair value of the Company’s financial instruments by level within the fair value hierarchy: As of December 31, 2023 (in thousands) Fair Level 1 Level 2 Level 3 Assets Money market funds $ 120,987 $ 120,987 $ — $ — Marketable securities: U.S. treasury bills and notes 148,107 — 148,107 — U.S. agency securities 269,663 — 269,663 — Total assets $ 538,757 $ 120,987 $ 417,770 $ — Liabilities Success payment liability $ 2,720 — — $ 2,720 Total liabilities $ 2,720 $ — $ — $ 2,720 As of December 31, 2022 (in thousands) Fair Level 1 Level 2 Level 3 Assets Money market funds $ 105,303 $ 105,303 $ — $ — Marketable securities: U.S. treasury bills and notes 228,144 — 228,144 — U.S. agency securities 211,252 — 211,252 — Total assets $ 544,699 $ 105,303 $ 439,396 $ — Liabilities Success payment liability $ 2,885 $ — $ — $ 2,885 Total liabilities $ 2,885 $ — $ — $ 2,885
Schedule of Fair Value Liabilities Measured on Recurring Basis	The primary inputs used in valuing the success payments liability associated with the Company’s realization of a certain valuation threshold through either a sale of the Company’s preferred stock or a company sale at December 31, 2023, 2022 and 2021, were as follows: At At At Fair value of common stock (per share) $ 13.94 $ 19.35 $ 36.87 Equity volatility 83 % 84 % 77 %
Schedule of Reconciliation of Changes in Fair Value of Financial Instruments	The reconciliation of changes in the fair value of financial instruments based on Level 3 inputs were as follows: (in thousands) Success Balance at December 31, 2021 $ 4,371 Change in fair value ( 1,486 ) Balance at December 31, 2022 $ 2,885 Change in fair value ( 165 ) Balance at December 31, 2023 $ 2,720

Accrued expenses (Tables)

Accrued expenses (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: December 31, (in thousands) 2023 2022 Employee compensation and related benefits $ 12,342 $ 9,124 Accrued external research and development expenses 4,856 8,919 Professional fees 1,492 1,193 License and milestone payments 500 310 Other 988 1,221 Total $ 20,178 $ 20,767

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Components of Operating Lease Cost	The components of operating lease cost were as follows: (in thousands) December 31, 2023 December 31, 2022 Operating lease costs $ 12,936 $ 5,946 Variable lease costs 3,854 1,601 Short term lease costs 1,259 698 Total $ 18,049 $ 8,245
Supplemental Cash Flow Information Related to Operating Leases	Supplemental cash flow information related to operating leases was as follows: (in thousands) December 31, 2023 December 31, 2022 Cash paid for amounts included in the measurements of lease liabilities: Operating cash flows related to operating leases $ 12,550 $ 5,050
Schedule of Future Minimum Lease Commitments under Non-Cancellable Leases	Future minimum commitments under non-cancellable leases as of December 31, 2023 were as follows: Years ending December 31, Amount (in thousands) 2024 $ 10,563 2025 10,868 2026 11,183 2027 11,506 2028 11,839 Thereafter 50,075 Total lease payments $ 106,034 Less: interest ( 31,127 ) Present value of operating lease liabilities $ 74,907

Collaboration and License Agr_2

Collaboration and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2023
Vertex Agreement [Member]
Statement [Table]
Schedule of transaction price separate performance obligations	: Performance obligation Amount (in thousands) Research services obligation $ 5,845 First licensed agent material right 6,667 Second licensed agent material right 6,667 Third licensed agent material right 6,666 Total $ 25,845 The amount allocated to the Initial Vertex Research Services obligation was recognized on a proportional performance basis over the period of service using input-based measurements of total cost of research incurred to estimate the proportion performed and remeasured at the end of each reporting period. The amount allocated to the licensed agent material rights was recorded as deferred revenue and will commence recognition upon exercise of each option or, if an option is never exercised, it will be recognized in full upon expiry of the Vertex Research Term
Lilly Agreement [Member]
Statement [Table]
Schedule of transaction price separate performance obligations	As such, based on the relative standalone selling price for each of the material rights, the allocation of the transaction price to the separate performance obligations, at inception, is as follows: Performance obligation Amount (in thousands) Research services obligation $ 16,398 First licensed product material right 14,270 Second licensed product material right 14,270 Total $ 44,938

Stock-based compensation (Table

Stock-based compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Stock Based Compensation Expense	Stock-based compensation expense recorded in the consolidated statements of operations and comprehensive loss is as follows: Year ended (in thousands) 2023 2022 2021 Research and development $ 19,125 $ 12,486 $ 3,830 General and administrative 15,991 9,991 3,242 Total stock-based compensation expense $ 35,116 $ 22,477 $ 7,072
Schedule of Assumptions Used for Options Granted	The assumptions used in Black-Scholes for stock options granted were as follows: Year ended 2023 2022 2021 Expected volatility 77.7 % 77.3 % 77.7 % Weighted-average risk-free interest rate 4.0 % 2.4 % 0.9 % Expected dividend yield — — — Expected term (in years) 6.0 6.0 6.0
Schedule of Stock Option Activity	The following table provides a summary of stock option activity during the year ended December 31, 2023: Number of Weighted Weighted Aggregate (2) Outstanding at December 31, 2022 7,612,826 $ 16.10 Granted 3,152,042 19.83 Exercised ( 240,182 ) 5.00 Forfeited ( 599,808 ) 25.57 Outstanding at December 31, 2023 9,924,878 $ 16.98 7.8 $ 36,695 Exercisable at December 31, 2023 4,549,532 $ 12.49 6.9 $ 29,820 Expected to vest after December 31, 2023 (1) 5,375,346 $ 20.79 8.6 $ 6,875 (1) This represents the number of unvested options outstanding as of December 31, 2023 that are expected to vest in the future. (2) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the common stock for the options that were in the money as of December 31, 2023 .
Schedule of Status and Change in Unvested Restricted Stock and Restricted Stock Units	A summary of the status of and change in unvested restricted stock units as of December 31, 2023 was as follows: Shares Weighted- Unvested restricted stock units as of December 31, 2022 677,825 $ 23.10 Restricted stock units granted 572,140 $ 17.76 Restricted stock units vested ( 149,456 ) $ 22.58 Restricted stock units forfeited ( 135,998 ) $ 23.74 Unvested restricted stock units as of December 31, 2023 964,511 $ 19.92

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted net Loss Per Share	The following table summarizes the computation of basic and diluted net loss per share: Year ended December 31, (in thousands, except share and per share amounts) 2023 2022 2021 Numerator: Net loss $ ( 200,068 ) $ ( 157,387 ) $ ( 120,314 ) Denominator: Weighted average number of common shares, basic and diluted 64,175,137 54,023,653 26,872,036 Net loss per common share, basic and diluted $ ( 3.12 ) $ ( 2.91 ) $ ( 4.48 )
Potential Common Shares, Based on Amounts Outstanding at Period End were Excluded From the Computation of Diluted Net Loss Per Share Attributable to Common Stockholders	The Company excluded the following potential common shares, presented based on amounts outstanding at period end, from the computation of diluted net loss per share for the period indicated because including them would have had an anti-dilutive effect: Year ended December 31, 2023 2022 2021 Unvested restricted stock units 964,511 677,825 32,000 Outstanding options to purchase common stock 9,924,878 7,612,826 6,119,295 Total 10,889,389 8,290,651 6,151,295

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Summary of Income Tax Expense (Benefit)	Income tax expense (benefit) is summarized as follows: Year ended December 31, (in thousands) 2023 2022 2021 Current: Federal $ - $ - $ - State 275 53 - Foreign - - - Total current provision $ 275 $ 53 $ - Deferred: Federal - - - State - - - Foreign - - - Total deferred provision $ - $ - $ -
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the income tax expense computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year ended December 31, (in thousands) 2023 2022 2021 Federal statutory rate 21.0 % 21.0 % 21.0 % Change in valuation allowance ( 31.3 )% ( 34.7 )% ( 31.3 )% Stock-based compensation ( 1.0 )% ( 0.3 )% 0.9 % Executive compensation ( 0.2 )% ( 0.8 )% ( 1.1 )% Permanent items ( 0.1 )% ( 0.2 )% ( 0.1 )% State income taxes, net of federal benefit 8.2 % 8.4 % 6.1 % Research and development tax credits 3.6 % 5.6 % 4.5 % Other ( 0.3 )% 1.0 % 0.0 % Effective income tax rate ( 0.1 )% — % — %
Schedule of Deferred Taxes	: December 31, (in thousands) 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 51,295 $ 43,779 Capitalized costs—net of amortization 10,844 11,095 Research and development tax credits 31,220 20,835 Capitalized research costs 64,255 28,650 Deferred revenue 5,525 77 Stock-based compensation 8,926 3,669 Other 134 97 Lease liability 20,646 22,285 Accrued expenses 3,726 5,024 Total deferred tax assets 196,571 135,511 Deferred tax liabilities: Property and equipment ( 1,207 ) ( 881 ) Right of use asset ( 23,254 ) ( 24,994 ) Total deferred tax liabilities ( 24,461 ) ( 25,875 ) Total deferred tax assets, net 172,110 109,636 Less: valuation allowance ( 172,110 ) ( 109,636 ) Deferred tax assets, net of valuation allowance $ — $ —

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Additional Information (Details) $ in Millions	Dec. 31, 2023 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash, cash equivalents, and marketable securities	$ 624

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 206,180	$ 115,412
Restricted cash	4,774	4,824
Total cash, cash equivalents and restricted cash	$ 210,954	$ 120,236	$ 69,567	$ 9,456

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) Segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2021 shares
Summary Of Significant Accounting Policies [Line Items]
Impairment losses	$ 0	$ 0	$ 0
Percentage of tax benefit realized	50%
Number of operating segment | Segment	1
Present value of operating lease liabilities	$ 74,907,000
Operating lease right-of-use assets	85,295,000	91,877,000
Operating Lease, Right-of-Use Asset	85,295,000	$ 91,877,000
Operating Lease, Liability	74,907,000
Harvard and Board
Summary Of Significant Accounting Policies [Line Items]
Success payment liability, payable	$ 10,000,000,000
Issuance of Additional Common Stock | shares				878,098
Success Liability Payment			$ 6,300,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Property and Equipment Estimated Useful Life (Details)	12 Months Ended
	Dec. 31, 2023
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment estimated useful life	3 years
Office Furniture
Property Plant And Equipment [Line Items]
Property and equipment estimated useful life	4 years
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment estimated useful life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Leasehold useful life	Shorter of useful life or remaining lease term

Marketable Securities - Schedul

Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current [Abstract]
Debt Securities, Available-for-Sale, Amortized Cost, Current	$ 417,498	$ 440,090
Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Current	421	81
Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Current	(149)	(775)
Debt Securities, Available-for-Sale, Current	417,770	439,396
U.S. Treasury Bills and Notes [Member]
Current [Abstract]
Debt Securities, Available-for-Sale, Amortized Cost, Current	147,978	228,432
Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Current	144	13
Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Current	(15)	(301)
Debt Securities, Available-for-Sale, Current	148,107	228,144
U.S. Agency Securities [Member]
Current [Abstract]
Debt Securities, Available-for-Sale, Amortized Cost, Current	269,520	211,658
Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Current	277	68
Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Current	(134)	(474)
Debt Securities, Available-for-Sale, Current	$ 269,663	$ 211,252

Marketable securities - Additio

Marketable securities - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Remaining contractual maturities of marketable securities term	12 months	12 months
Unrealized losses on marketable securities	$ 0.1	$ 0.8

Property and equipment, net - S

Property and equipment, net - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Total property and equipment	$ 32,897	$ 23,765
Less accumulated depreciation	(10,392)	(4,987)
Property and equipment, net	22,505	18,778
Lab equipment
Property Plant And Equipment [Line Items]
Total property and equipment	28,851	20,379
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	726	266
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	2,323	2,294
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 997	$ 826

Property and equipment, net -_2

Property and equipment, net - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 5,455	$ 2,804	$ 1,535

Property and equipment, net - A

Property and equipment, net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation	$ 5,455	$ 2,804	$ 1,535

Fair value of financial instr_3

Fair value of financial instruments - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets
Total assets	$ 538,757	$ 544,699
Liabilities
Total liabilities	2,720	2,885
Money Market Funds
Assets
Total assets	120,987	105,303
U.S. Treasury Bills and Notes
Assets
Total assets	148,107	228,144
U.S. Agency Securities
Assets
Total assets	269,663	211,252
Success Payment Liability
Liabilities
Total liabilities	2,720	2,885
Level 1
Assets
Total assets	120,987	105,303
Liabilities
Total liabilities	0	0
Level 1 | Money Market Funds
Assets
Total assets	120,987	105,303
Level 1 | U.S. Treasury Bills and Notes
Assets
Total assets	0	0
Level 1 | U.S. Agency Securities
Assets
Total assets	0	0
Level 1 | Success Payment Liability
Liabilities
Total liabilities	0	0
Level 2
Assets
Total assets	417,770	439,396
Liabilities
Total liabilities	0	0
Level 2 | Money Market Funds
Assets
Total assets	0	0
Level 2 | U.S. Treasury Bills and Notes
Assets
Total assets	148,107	228,144
Level 2 | U.S. Agency Securities
Assets
Total assets	269,663	211,252
Level 2 | Success Payment Liability
Liabilities
Total liabilities	0	0
Level 3
Assets
Total assets	0	0
Liabilities
Total liabilities	2,720	2,885
Level 3 | Money Market Funds
Assets
Total assets	0	0
Level 3 | U.S. Treasury Bills and Notes
Assets
Total assets	0	0
Level 3 | U.S. Agency Securities
Assets
Total assets	0	0
Level 3 | Success Payment Liability
Liabilities
Total liabilities	$ 2,720	$ 2,885

Fair value of financial instr_4

Fair value of financial instruments - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 121,000	$ 105,300
Common Stock, Shares Issued	81,969,693	61,730,816
Issuance of common stock, value	$ 82	$ 62
Harvard and Board
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, payable	$ 10,000,000
Success payment, current portion				$ 6,300
Broad License Agreement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Common Stock, Shares Issued	276,075
Maximum | Harvard
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, payable	$ 31,300
Other Expense
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success Payment Liability, Payable	$ 200	$ 1,500	$ 7,800

Fair value of financial instr_5

Fair value of financial instruments - Schedule of Fair Value Liabilities Measured on Recurring Basis (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of common stock (per share)	$ 13.94	$ 19.35	$ 36.87
Equity Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity volatility	83%	84%	77%

Fair value of financial instr_6

Fair value of financial instruments - Schedule of Reconciliation of Changes in Fair Value of Financial Instruments (Details) - Success Payment Liability - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 2,885	$ 4,371
Changes in fair value	(165)	(1,486)
Ending balance	$ 2,720	$ 2,885

Accrued expenses - Schedule of

Accrued expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Employee compensation and related benefits	$ 12,342	$ 9,124
Accrued external research and development expenses	4,856	8,919
Professional fees	1,492	1,193
License and milestone payments	500	310
Other	988	1,221
Total	$ 20,178	$ 20,767

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Aug. 19, 2021 USD ($) ft²	Aug. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 31, 2022 ft²
Lessee Lease Description [Line Items]
Increase in Right-Of-Use assets		$ 91,800
Increase in operating lease liability		$ 80,800	$ (7,220)	$ (3,011)	$ (1,940)
Present value of operating lease liabilities			74,907
Operating lease right-of-use assets			$ 85,295	91,877
Operating lease incremental borrowing rate			7.89%
Weighted average remaining lease term			9 years
Operating lease payments			$ 12,550	5,050
Short term lease costs			1,259	$ 698
New Amendment
Lessee Lease Description [Line Items]
Lease area | ft²						105,182
Additional Lease Area | ft²						249
Premises
Lessee Lease Description [Line Items]
Lease area | ft²	104,933
Lease not yet commenced, lease term	10 years
Option to extend, lease not yet commenced	five years
Tenant improvements allowance	$ 21,000
Prepaid rent			$ 800
Increase decrease in rent			3%
Rent paid			$ 800
Premises | Letter of Credit
Lessee Lease Description [Line Items]
Letter of credit issued	4,800
Letter of credit reduced value	$ 3,500

Leases - Summary of Components

Leases - Summary of Components of Operating Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Lease, Cost [Abstract]
Operating lease costs	$ 12,936	$ 5,946
Variable lease costs	3,854	1,601
Short term lease costs	1,259	698
Total	$ 18,049	$ 8,245

Leases - Summary of Supplementa

Leases - Summary of Supplemental Cash Flow Information Related to Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash paid for amounts included in the measurements of lease liabilities [Abstract]
Operating cash flows related to operating leases	$ 12,550	$ 5,050

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Commitments under Non-Cancellable Operating Leases (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2024	$ 10,563
2025	10,868
2026	11,183
2027	11,506
2028	11,839
Thereafter	50,075
Total lease payments	106,034
Less: interest	(31,127)
Present value of operating lease liabilities	$ 74,907

License Agreements - Additional

License Agreements - Additional Information (Details) - USD ($)	1 Months Ended	10 Months Ended	12 Months Ended
	Oct. 31, 2023	Oct. 31, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Apr. 30, 2019
Research And Development Arrangement Contract To Perform For Others [Line Items]
Common stock, shares issued			81,969,693	61,730,816
Issuance of common stock			$ 134,736,000	$ 242,826,000	$ 281,584,000
Issuance of common stock, value			82,000	62,000
Research and development expense			$ 184,946,000	$ 130,095,000	68,202,000
Preferred stock, shares issued			0	0
Non-US
Research And Development Arrangement Contract To Perform For Others [Line Items]
Payment of sales based milestone	$ 7,500,000
Broad License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Common stock, shares issued			276,075
Issuance of common stock			$ 300,000
Preferred stock financing partially satisfied							$ 100,000
Preferred stock financing were fully satisfied						$ 500,000
Common stock issued for partly satisfying preferred stock financing							$ 121,411
Common stock issued for fully satisfying preferred stock financing						187,867
Payment of milestone development			46,200,000
Payment of sales based milestone			108,000,000
Harvard and Board
Research And Development Arrangement Contract To Perform For Others [Line Items]
Success payment liability			$ 300,000		6,300,000			$ 6,300,000
Derivative Liability, Statement of Financial Position [Extensible Enumeration]			Liabilities					Liabilities
Beam License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Common stock, shares issued									276,075
Description of opt-in fees payment	In October 2023, Beam and Eli Lilly and Company (“Lilly”) entered into the Transfer and Delegation Agreement (“TDA”), pursuant to which Lilly acquired certain rights previously held by Beam under the ARCLA. This included the right to opt-in to the Company’s PCSK9 and ANGPTL3 programs to share 33% of worldwide development expenses and to jointly commercialize and share profits and expenses related to commercialization in the United States on a 50/50 basis. Additionally, for an undisclosed third cardiovascular disease gene target, Lilly acquired Beam’s right to opt-in to share 35% of worldwide expenses of the development of such licensed product, as well as jointly commercialize and share 35% of the profits and expenses of commercializing such licensed product worldwide.
Payment of milestone development	$ 11,300,000
Payment of sales based milestone	$ 15,000,000
Commercializing Profits And Expenses			35%
Percentage Shares of Development Expense	33%		35%
Percentage of Promotional Effort	50%
Beam License Agreement | Non-US
Research And Development Arrangement Contract To Perform For Others [Line Items]
Payment of milestone development	$ 5,600,000
Beam License Agreement | Sales Member
Research And Development Arrangement Contract To Perform For Others [Line Items]
Payment of sales based milestone				$ 200,000
Beam License Agreement | Sales Member | N Z
Research And Development Arrangement Contract To Perform For Others [Line Items]
Payment of sales based milestone				300,000
Novartis License Agreement Member
Research And Development Arrangement Contract To Perform For Others [Line Items]
Non-refundable upfront license fees paid					$ 800,000
Payment of sales based milestone			$ 35,000,000
Milestone related expenses			500,000
Non Refundable Upfront License Fee				2,800,000
Clinical And Regulatory Milestone			10,000,000
Acuitas Agreements
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development expense				100,000
License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development expense			0
Non Refundable Upfront License Fee		$ 2,000,000
Clinical And Regulatory Milestone				9,800,000
Sales Based Milestone				9,500,000
License Agreement | Broad License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Non-refundable upfront license fees paid			$ 300,000
License Agreement | Acuitas Agreements | Sales Member
Research And Development Arrangement Contract To Perform For Others [Line Items]
Payment of sales based milestone				$ 800,000
Antidilution Rights | Broad License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Common stock, shares issued			878,098
Issuance of common stock, value			$ 32,500,000

Collaboration and License Agr_3

Collaboration and License Agreements (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			12 Months Ended
	Jul. 31, 2022	Aug. 31, 2023	Jun. 30, 2023	Jul. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payments to Acquire Commercial Real Estate				$ 165
Shares issued and sold					2,780,853
Stock Purchase Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Fixed transaction price consisting upfront fee		$ 0.3
Vertex Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of common stock from initial public offering, net of issuance costs of (in shares)				1,519,756
Price Per Share	$ 23.03			$ 23.03
Aggregate purchase price				$ 35
Non Refundable Upfront Payment				25
Success payments for each product	$ 22			22
Payments to Acquire Commercial Real Estate				175
Fixed consideration amount					$ 20
Deferred Revenue, Revenue Recognized					8.5	$ 1.9
Vertex Agreement [Member] | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Success payments for each product	$ 66			$ 66
Maximum percentage of profit/cost share	40%			40%
Vertex Agreement [Member] | Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum percentage of profit/cost share	60%			60%
Vertex Agreement [Member] | Stock Purchase Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Fixed transaction price	$ 20
Fixed transaction price consisting upfront fee	25
Upfront fee discount	$ 5			$ 5
Shares issued and sold	1,519,756
Estimated expected cost reimbursement	$ 5.8		$ 16.9	$ 5.8
Reimbursement related to Initial Research Services			$ 5.4
Lilly Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of common stock from initial public offering, net of issuance costs of (in shares)			1,552,795
Price Per Share			$ 19.32
Aggregate purchase price			$ 30
Non Refundable Upfront Payment		$ 30
Maximum percentage of profit/cost share		60%
Fixed consideration amount					28.5
Deferred Revenue, Revenue Recognized					3.2
Amount of Deferred Costs Related to Long-Term Contracts					28.5
Research and development milestone payments					190
Commercial Milestone Payments					$ 275
Lilly Agreement [Member] | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum percentage of profit/cost share		40%
Lilly Agreement [Member] | Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum percentage of profit/cost share		40%
Lilly Agreement [Member] | Stock Purchase Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non Refundable Upfront Payment		$ 0.3
Required fee payments		465
Fixed transaction price		28.5
Fixed transaction price consisting upfront fee		30
Upfront fee discount		$ 1.7
Shares issued and sold		1,552,795
Cost Reimbursement At Inception		$ 16.4

Collaboration and License Agr_4

Collaboration and License Agreements - Schedule of transaction price separate performance obligations (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Vertex Agreement [Member]
Performance obligation	$ 25,845
Vertex Agreement [Member] | Research services obligation [Member]
Performance obligation	5,845
Vertex Agreement [Member] | First licensed agent material right [Member]
Performance obligation	6,667
Vertex Agreement [Member] | Second licensed agent material right [Member]
Performance obligation	6,667
Vertex Agreement [Member] | Third licensed agent material right [Member]
Performance obligation	6,666
Lilly Agreement [Member]
Performance obligation	44,938
Lilly Agreement [Member] | Research services obligation [Member]
Performance obligation	16,398
Lilly Agreement [Member] | First licensed agent material right [Member]
Performance obligation	14,270
Lilly Agreement [Member] | Second licensed agent material right [Member]
Performance obligation	$ 14,270

Preferred Stock Tranche Liabili

Preferred Stock Tranche Liability - Additional Information (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, value per share	$ 0.001	$ 0.001
Preferred stock, shares issued	0	0

Preferred and Common Stock - Ad

Preferred and Common Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions			1 Months Ended	12 Months Ended
	Jul. 31, 2023	Jul. 31, 2022	Jun. 30, 2021	Dec. 31, 2023	Dec. 31, 2022
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares issued				0	0
Preferred stock, shares authorized				5,000,000	5,000,000
Common stock, shares authorized				200,000,000	200,000,000
Common Stock, Shares Issued				81,969,693	61,730,816
Common stock, par value				$ 0.001	$ 0.001
Sale of Stock, Number of Shares Issued in Transaction				2,780,853
Commission On Aggregate Gross Sale Proceeds		3%
Underwriting discounts and offering expenses		$ 15.8		$ 9
Sale of Stock, Consideration Received on Transaction				$ 63.5
Sales Agreement [Member]
Subsidiary Sale Of Stock [Line Items]
Common Stock, Shares Issued		1,519,756		2,296,317
Common stock, par value	$ 19.32	$ 23.03		$ 10
Agreegate Purchase Price		$ 35
IPO
Subsidiary Sale Of Stock [Line Items]
Proceeds from issuance of Preferred Stock, net				$ 281.6
Additional shares of common stock			2,105,368
Public Offering Price			$ 19
Proceeds from common stock, gross			$ 306.7
Shares issued upon conversion of preferred stock				27,720,923
Stock Purchase Agreement [Member]
Subsidiary Sale Of Stock [Line Items]
Agreegate Purchase Price	$ 30			$ 23
Public Offering [Member]
Subsidiary Sale Of Stock [Line Items]
Common Stock, Shares Issued		1,250,000		1,875,000
Sale of Stock, Number of Shares Issued in Transaction		9,583,334		14,375,000
Common Stock Offering Price Per Share		$ 27		$ 10
Sale of Stock, Consideration Received on Transaction		$ 242.9		$ 134.7
Lilly Agreement [Member]
Subsidiary Sale Of Stock [Line Items]
Common Stock, Shares Issued	1,552,795
Harvard And Board [Member]
Subsidiary Sale Of Stock [Line Items]
Common Stock, Shares Issued			878,098
Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares authorized			5,000,000
Preferred Stock | Series A Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares issued				101,170,571
Preferred Stock | Series A-2 Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares issued				7,838,461
Preferred Stock | Series B Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares issued				77,163,022
Common Stock
Subsidiary Sale Of Stock [Line Items]
Common stock, shares authorized			200,000,000
Common stock, par value			$ 0.001
Common Stock | Sales Agreement [Member]
Subsidiary Sale Of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction				1,766,835
Sale of Stock, Consideration Received on Transaction				$ 22.5
Common Stock | IPO
Subsidiary Sale Of Stock [Line Items]
Common Stock, Shares Issued			16,141,157
Common Stock | Series B Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares issued				77,163,022

Stock-based compensation - Addi

Stock-based compensation - Additional Information (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($) Instalment	Dec. 31, 2018 shares	Jan. 01, 2024 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance	10,144,170
Proceeds from exercise of stock options | $	$ 1,200	$ 2,175	$ 966
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value of stock options granted | $ / shares		$ 19.83
Aggregate intrinsic value of stock options exercised | $	2,800
Proceeds from exercise of stock options | $	1,200
Unrecognized stock-based compensation cost | $	$ 68,800
Weighted average period over which unrecognized compensation is expected to be recognized	2 years 4 months 24 days
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period over which unrecognized compensation is expected to be recognized	3 years 1 month 6 days
Unrecognized stock-based compensation cost | $	$ 16,100
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of common stock under employee stock purchase plan (shares)				2,150,537
Number of Installments for Restricted Shares Vested | Instalment			48
Twenty Eighteen | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance	6,885,653
2021 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance					4,098,485
Shares available for future grant	3,123,972
Purchase of common stock under employee stock purchase plan (shares)	258,549
Stock available for issuance under ESPP	1,277,192
Number of RSUs, Granted	572,140
2021 Stock Incentive Plan | Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grant	572,140
Vesting period	4 years
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in common stock capital shares, reserved for future issuance					819,697

Stock-based compensation - Summ

Stock-based compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 35,116	$ 22,477	$ 7,072
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	19,125	12,486	3,830
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 15,991	$ 9,991	$ 3,242

Stock-based compensation - Sche

Stock-based compensation - Schedule of Assumptions Used for Options Granted (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Expected volatility	77.70%	77.30%	77.70%
Weighted-average risk-free interest rate	4%	2.40%	0.90%
Expected dividend yield	0%	0%	0%
Expected term (in years)	6 years	6 years	6 years

Stock-based compensation - Sc_2

Stock-based compensation - Schedule of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number of options, Outstanding, Beginning balance | shares	7,612,826
Number of options, Granted | shares	3,152,042
Number of options, Exercised | shares	(240,182)
Number of options, Forfeited | shares	(599,808)
Number of options, Outstanding, Ending balance | shares	9,924,878
Number of options, Exercisable | shares	4,549,532
Number of options, Expected to vest | shares	5,375,346	[1]
Weighted average exercise price, Beginning balance | $ / shares	$ 16.10
Weighted average exercise price, Granted | $ / shares	19.83
Weighted average exercise price, Exercised | $ / shares	5
Weighted average exercise price, Forfeited | $ / shares	25.57
Weighted average exercise price, Ending balance | $ / shares	16.98
Weighted average exercise price, Exercisable | $ / shares	12.49
Weighted average exercise price, Expected to vest | $ / shares	$ 20.79	[1]
Weighted average remaining contractual life (in years), Outstanding	7 years 9 months 18 days
Weighted average remaining contractual life (in years), Exercisable	6 years 10 months 24 days
Weighted average remaining contractual life (in years), Expected to vest	8 years 7 months 6 days	[1]
Aggregate intrinsic value, Outstanding | $	$ 36,695	[2]
Aggregate intrinsic value, Exercisable | $	29,820	[2]
Aggregate intrinsic value, Expected to vest | $	$ 6,875	[1],[2]
[1] This represents the number of unvested options outstanding as of December 31, 2023 that are expected to vest in the future. The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the common stock for the options that were in the money as of December 31, 2023 .

Stock-based compensation - Sc_3

Stock-based compensation - Schedule of Status and Change in Unvested Restricted Stock and Restricted Stock Units (Details) - 2021 Stock Incentive Plan	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unvested RSUs, beginning balance, Unvested | shares	677,825
Number of RSUs, Granted | shares	572,140
Unvested Restricted stock vested | shares	(149,456)
Restricted stock units forfeited | shares	(135,998)
Unvested RSUs, ending balance, Unvested | shares	964,511
Weighted-Average Grant Date Fair Value Per Share, beginning balance, Unvested | $ / shares	$ 23.1
Weighted-Average Grant-Date Fair Value, Granted | $ / shares	17.76
Weighted-Average Grant Date Fair Value Per Share, Vested | $ / shares	22.58
Weighted-Average Grant-Date Fair Value, forfeited | $ / shares	23.74
Weighted-Average Grant Date Fair Value Per Share, ending balance, Unvested | $ / shares	$ 19.92

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss attributable to common stockholders	$ (200,068)	$ (157,387)	$ (120,314)
Denominator:
Weighted average number of common shares, basic	64,175,137	54,023,653	26,872,036
Weighted average number of common shares, diluted	64,175,137	54,023,653	26,872,036
Net loss per common share attributable to common stockholders, basic	$ (3.12)	$ (2.91)	$ (4.48)
Net loss per common share attributable to common stockholders, diluted	$ (3.12)	$ (2.91)	$ (4.48)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Potential Common Shares, Based on Amounts Outstanding at Period End were Excluded From the Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	10,889,389	8,290,651	6,151,295
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	964,511	677,825	32,000
Outstanding Options To Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	9,924,878	7,612,826	6,119,295

Net Loss Per Share Attributab_5

Net Loss Per Share Attributable to Common Stockholders - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share Basic [Line Items]
Success payment liability	$ 2,720	$ 2,885

Income taxes - Summary of Incom

Income taxes - Summary of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 0	$ 0	$ 0
State	275	53	0
Foreign	0	0	0
Total current provision	275	53	0
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	0	0	0
Total deferred provision	$ 0	$ 0	$ 0

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory rate	21%	21%	21%
Change in valuation allowance	(31.30%)	(34.70%)	(31.30%)
Stock-based compensation	(1.00%)	0.30%	0.90%
Executive compensation	(0.20%)	(0.80%)	(1.10%)
Permanent items	(0.10%)	(0.20%)	(0.10%)
State income taxes, net of federal benefit	8.20%	8.40%	6.10%
Research and development tax credits	3.60%	5.60%	4.50%
Other	(0.30%)	1%	0%
Total	(0.10%)	0%	0%

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 51,295	$ 43,779
Capitalized costs—net of amortization	10,844	11,095
Research and development tax credits	31,220	20,835
Capitalized research costs	64,255	28,650
Deferred revenue	5,525	77
Stock-based compensation	8,926	3,669
Other	134	97
Lease liability	20,646	22,285
Accrued expenses	3,726	5,024
Total deferred tax assets	196,571	135,511
Deferred tax liabilities:
Property and equipment	(1,207)	(881)
Right of use asset	(23,254)	(24,994)
Total deferred tax liabilities	(24,461)	(25,875)
Total deferred tax assets, net	172,110	109,636
Less: valuation allowance	(172,110)	(109,636)
Deferred tax assets, net of valuation allowance	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	$ 275,000	$ 53,000	$ 0
Income (Loss) from Continuing Operations before Income Taxes, Domestic	199,800,000	157,300,000	$ 120,300,000
Deferred tax assets valuation allowance increase (decrease)	$ 62,500,000
Change in ownership, description	An ownership change occurs when the ownership percentages of 5% or greater shareholders change by more than 50% over a three-year period.
Uncertain tax positions	$ 0	$ 0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	0
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	188,200,000
Tax credit amount	$ 20,900,000
Tax credit carryforward expiration year	2035
Federal | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration year	2039
Federal | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration year	2043
State
Operating Loss Carryforwards [Line Items]
Percentage of future taxable income utilized to offset	80%
Net operating loss carryforwards	$ 186,100,000
State | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration year	2038
State | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration year	2043
Massachusetts
Operating Loss Carryforwards [Line Items]
Tax credit amount	$ 13,100,000
Tax credit carryforward expiration year	2024

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Research and development expense	$ 184,946	$ 130,095	$ 68,202
Lease Rent Payment		1,800
Beam | Materials Exchange Agreement | Research and Development
Related Party Transaction [Line Items]
Research and development expense		$ 400

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($)		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, maximum annual contributions per employee, amount		$ 7,500
401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan employer matching contribution percent of match upto two percent of employee salary		2%
Defined contribution plan, maximum annual contributions per employee, amount		$ 22,500
Defined contribution plan, employer matching contribution, percent of match upto 3% of employee's salary	100%	3%
Defined contribution plan, employer matching contribution, percent of match after 3% and before 5% of employee's salary	50%
Defined contribution plan, employers matching contribution, annual vesting percentage	100%
Defined contribution plan, description		The 401(k) Plan includes a salary deferral arrangement pursuant to which participants may elect to reduce their current compensation by up to the statutorily prescribed limit, equal to $22,500 in 2023 with a catch up contribution limit equal to $7,500 for those 50 years of age or older, and have the amount of the reduction contributed to the 401(k) Plan.
Defined contribution plan, employer Contribution amount		$ 1,500,000	$ 1,000,000	$ 400,000

Subsequent Events (Additional I

Subsequent Events (Additional Information) (Details) - shares	Feb. 27, 2024	Dec. 31, 2023
Subsequent Event [Line Items]
Shares of common stock reserved for future issuance		10,144,170
Subsequent Event | 2024 Inducement Stock Incentive Plan
Subsequent Event [Line Items]
Shares of common stock reserved for future issuance	4,000,000