0000950170-23-005713 | 10-K | XBRL Viewer

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Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2022	Feb. 27, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
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	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 557.6
Entity Common Stock, Shares Outstanding		61,833,265
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 2023 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, 2022, 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 - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 115,412	$ 64,330
Marketable securities	439,396	296,112
Collaboration receivable	1,012	0
Prepaid expenses and other current assets	7,339	6,686
Total current assets	563,159	367,128
Property and equipment, net	18,778	7,224
Restricted cash	4,824	5,237
Operating lease right-of-use assets	91,877	1,839
Other long term assets	585	2,696
Total assets	679,223	384,124
Current liabilities:
Accounts payable	2,424	7,077
Accrued expenses	20,767	12,992
Operating lease obligations, current portion	11,904	1,955
Total current liabilities	35,095	22,024
Long-term lease liability	70,014	0
Deferred revenue, non-current	20,014
Success payment liability	2,885	4,371
Other long term liabilities	283	377
Total liabilities	128,291	26,772
Commitments and contingencies (See Note 7 and 8)
Convertible preferred stock (See Note 10)	0	0
Stockholders’ equtiy (deficit):
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 and 255,000,000 shares authorized at December 31, 2022 and 2021, respectively, 61,730,816 and 48,511,735 shares issued at December 31, 2022 and 2021, respectively; 61,730,816 and 48,511,735 shares outstanding at December 31, 2022 and 2021, respectively	62	49
Additional paid-in capital	895,801	544,381
Accumulated other comprehensive (loss) income	(694)	(228)
Accumulated deficit	(344,237)	(186,850)
Total stockholders’ equity (deficit)	550,932	357,352
Total liabilities, and stockholders' equity	$ 679,223	$ 384,124

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
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	61,730,816	48,511,735
Common stock, shares outstanding	61,730,816	48,511,735

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Collaborations revenue	$ 1,941	$ 0	$ 0
Operating expenses:
Research and development	130,095	68,202	35,371
General and administrative	37,533	18,865	5,256
Total operating expenses	167,628	87,067	40,627
Loss from operations	(165,687)	(87,067)	(40,627)
Other income (expense):
Change in fair value of preferred stock tranche liability	0	0	2,507
Change in fair value of antidilution rights liability	0	(25,574)	(5,359)
Change in fair value of success payment liability	1,486	(7,815)	(2,387)
Interest and other income, net	6,867	142	162
Total other expense, net	8,353	(33,247)	(5,077)
Loss before provision for income taxes	(157,334)	(120,314)	(45,704)
Provision for income taxes	53	0	0
Net loss	$ (157,387)	$ (120,314)	$ (45,704)
Net loss per common share attributable to common stockholders, basic	$ (2.91)	$ (4.48)	$ (20.31)
Net loss per common share attributable to common stockholders, diluted	$ (2.91)	$ (4.48)	$ (20.31)
Weighted-average common shares used in net loss per share attributable to common stockholders, basic	54,023,653	26,872,036	2,250,093
Weighted-average common shares used in net loss per share attributable to common stockholders, diluted	54,023,653	26,872,036	2,250,093
Comprehensive Loss:
Net loss	$ (157,387)	$ (120,314)	$ (45,704)
Other comprehensive loss:
Unrealized loss on marketable securities	(466)	(236)	(1)
Comprehensive loss	$ (157,853)	$ (120,550)	$ (45,705)

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, 2019	$ (19,553)	$ 2	$ 1,268	$ 9	$ (20,832)	$ 25,480
Beginning balance (in shares) at Dec. 31, 2019		1,854,438				51,421,404
Issuance of Series A convertible preferred stock and settlement of tranche right liability, net of issuance costs						$ 36,792
Issuance of Series A convertible preferred stock and settlement of tranche right liability, net of issuance costs (in shares)						49,749,167
Issuance of Series A-2 convertible preferred stock, net of issuance costs of $112						$ 62,888
Issuance of Series A-2 convertible preferred stock, net of issuance costs (in shares)						78,348,461
Additional issuances of common stock to licensor institutions	487		487
Additional issuances of common stock to licensor institutions (in shares)		187,867
Vesting of restricted common stock	1	$ 1
Vesting of restricted common stock (in shares)		537,635
Exercise of stock options	11		11
Exercise of stock options (in shares)		5,849
Unrealized loss on available-for-sale securities	(1)			(1)
Stock-based compensation	850		850
Net loss	(45,704)				(45,704)
Ending balance at Dec. 31, 2020	(63,909)	$ 3	2,616	8	(66,536)	$ 125,160
Ending 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 ESPP	780		780
Purchase of common stock under ESPP(shares)		48,297
Unrealized loss on available-for-sale securities	(236)			(236)
Stock-based compensation	7,072		7,072
Net 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	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	743,638
Purchase of common stock under ESPP	$ 1,069		1,069
Purchase of common stock under ESPP(shares)		85,810
Unrealized loss on available-for-sale securities	(466)			(466)
Stock-based compensation	22,477		22,477
Net 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

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Stockholders' Equity [Abstract]
Issuance of Series A convertible preferred stock and settlement of tranche right liability			$ 7,000
Issuance costs of series A convertible preferred stock			22
Issuance costs of series A2 convertible preferred stock			$ 112
Issuance costs of series B convertible preferred stock		$ 241
Issuance costs of common stock from initial public offering	$ 15,924	$ 25,098
Issuance of common stock from At-the-Market offering	$ 1,722,000

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (157,387)	$ (120,314)	$ (45,704)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	2,804	1,535	1,328
Non-cash lease expense	3,907	1,842	0
Net amortization of premium (accretion of discount) on marketable securities	(1,027)	1,508	380
Stock-based compensation	22,477	7,072	850
Change in fair value of preferred stock tranche liabilities	0	0	(2,507)
Change in fair value of antidilution rights	0	25,574	5,359
Change in fair value of success payments liabilities	(1,486)	7,815	2,387
Changes in operating assets and liabilities:
Collaboration receivable	(1,012)	0	0
Prepaid expenses and other current assets	(9,436)	(7,528)	(1,582)
Accounts payable	(5,216)	6,829	(1,898)
Accrued expenses and other liabilities	7,041	5,977	6,071
Success of payment liability	0	(6,250)	0
Deferred revenue	20,014	0	0
Operating lease liabilities	(3,011)	(1,940)	0
Deferred rent liability	0	0	51
Net cash used in operating activities	(122,332)	(77,880)	(35,265)
Cash flows from investing activities:
Purchases of property and equipment	(13,232)	(4,359)	(3,424)
Purchases of marketable securities	(479,401)	(371,494)	(98,484)
Maturities of marketable securities	336,678	136,755	50,781
Net cash used in investing activities	(155,955)	(239,098)	(51,127)
Cash flows from financing activities
Proceeds from issuance of Preferred Stock, net	0	93,759	92,616
Proceeds from the issuance of common stock in connection with the Vertex Agreement	39,986
Proceeds from issuance of common shares, net of commissions	286,509	285,214	0
Payment of equity offering costs	(783)	(3,630)	0
Proceeds from exercise of stock options	2,175	966	11
Proceeds from purchase of shares through employee stock purchase plan	1,069	780	0
Net cash provided by financing activities	328,956	377,089	92,627
Increase (decrease) in cash, cash equivalents and restricted cash	50,669	60,111	6,235
Cash, cash equivalents and restricted cash—beginning of period	69,567	9,456	3,221
Cash, cash equivalents and restricted cash—end of period	120,236	69,567	9,456
Supplemental disclosure of noncash investing and finnacing activities:
Property and equipment additions included in accounts payable and accrued expenses	1,706	503	86
Settlement of tranche right liability	0	0	7,064
Conversion of convertible preferred stock to common stock upon closing of initial public offering	0	218,919	0
Settlement of derivative liability by issuing common stock	0	32,490	487
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 83,417	$ 809	$ 0

Nature of the Business and Basis of Presentation

12 Months Ended

Dec. 31, 2022

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 $554.8 million as of December 31, 2022, 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 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 Accounting Policies

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary 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 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. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the fair values of common stock (prior to completion of the Company's initial public offering ("IPO")), stock-based compensation, and the liabilities for antidilution rights and success payments. Actual results could differ from these estimates.

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)	2022		2021
Cash and cash equivalents	$	115,412	$	64,330
Restricted cash		4,824		5,237
Total cash, cash equivalents and restricted cash	$	120,236	$	69,567

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).

The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period. The Company evaluated its securities for other-than-temporary impairment and considered the decline in market value for the securities to be primarily attributable to current economic and market conditions. It is not more likely than not that the Company will be required to sell the securities, and the Company does not intend to do so prior to the recovery of the amortized cost basis. Based on this analysis, these marketable securities were not considered to be other-than-temporarily impaired as of December 31, 2022 and 2021.

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, 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 judgement. Accordingly, the degree of judgement 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, 2022, 2021 and 2020. 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, 2022 and 2021.

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, 2022, 2021 and 2020.

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.

Preferred Stock Tranche Liabilities—The Company has determined that its obligation to issue, and the Company’s investors’ right to purchase, additional shares of convertible Series A Preferred Stock (“Series A Preferred”) pursuant to subsequent closings represent a freestanding financial instrument. The freestanding preferred stock tranche liability (the “tranche liability”) was initially recorded at fair value, with gains and losses arising from changes in fair value recognized in other income (expense) in the statement of operations and comprehensive loss. The tranche liabilities were remeasured at each reporting period and upon the exercise or expiration of the obligation. As of December 31, 2020, all Series A Preferred closings occurred, and all preferred stock tranche liabilities were settled. Refer to Note 9, Preferred Stock tranche liability, for additional discussion.

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 IPO in June 2021. Refer to Note 5, Fair value of financial instruments, for additional discussion.

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 high nine 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 year ended December 31, 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 judgement 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

During the quarter ended September 30, 2021, the Company early adopted ASC Topic 842, “Leases” (“ASC 842”) using the revised modified retrospective approach, which uses the effective date, or January 1, 2021, as the date of initial application. As a result, prior periods are presented in accordance with the previous guidance in ASC 840. As a result of the adoption of ASC 842, the Company recorded (i) an operating lease liability of $2.6 million determined using an incremental borrowing rate as of the effective adoption date and (ii) an operating lease right-of-use asset of $2.4 million, net of the unamortized balance of prepaid/accrued rent as of the transition date. There was no impact to the Company’s results of operations and cash flows from operations.

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, 2022, 2021 and 2020, the Company’s only element of other comprehensive loss was unrealized 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 attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders 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.

The Company’s convertible preferred stock contractually entitled the holders of such shares to participate in dividends but did not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss, such losses are not allocated to such participating securities. In periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is

anti-dilutive. The Company reported a net loss attributable to common stockholders for the years ended December 31, 2022, 2021 and 2020.

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 issued accounting pronouncements

The Jumpstart Our Business Startups Act of 2012 permits an emerging growth company ("EGC") to take advantage of an extended transition period to comply with new or revised accounting standards applicable to public companies until those standards would otherwise apply to private companies. As an EGC, the Company has elected to take advantage of this extended transition period for certain new accounting standards.

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 is currently 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 composition of the Company's investment portfolio, current market conditions, and historical credit loss activity, the Company does not expect the adoption of this standard to have a material impact on the consolidated financial statements and related disclosures.

Marketable Securities

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

3. Marketable securities

Marketable securities by security type consisted of the following:


	December 31, 2022
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
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


	December 31, 2021
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. treasury bills and notes	$	277,559	$	—	$	(218	)	$	277,341
U.S. agency securities		18,781		—		(10	)		18,771
Total	$	296,340	$	—	$	(228	)	$	296,112

The remaining contractual maturities of all marketable securities were less than 18 months as of December 31, 2022 and 2021.The unrealized losses on the Company’s marketable securities of $0.8 million and $0.2 million as of December 31, 2022 and 2021, respectively, were 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 does not consider those marketable securities to be

other-than-temporarily impaired at December 31, 2022 or 2021. None of the Company’s marketable securities have been in a continuous unrealized loss position for 12 months or greater as of December 31, 2022 or 2021.

Property and equipment, net

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Property and Equipment, net

4. Property and equipment, net

Property and equipment, net, consist of the following:


	December 31,
(in thousands)	2022			2021
Lab equipment		20,379		$	8,567
Leasehold improvements		266			266
Furniture and fixtures		2,294			566
Computer equipment		826			158
Total property and equipment		23,765			9,557
Less accumulated depreciation		(4,987	)		(2,333	)
Property and equipment, net	$	18,778		$	7,224


	Year ended December 31,
(in thousands)	2022		2021		2020
Depreciation expense	$	2,804	$	1,535	$	1,328

Fair value of financial instruments

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Disclosure - Fair Value of Financial Instruments

5. fair 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 and the Broad License Agreement. The antidilution right liability was fully settled in the year ended December 31, 2021. 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, 2022
(in thousands)	Fair value		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


	As of December 31, 2021
(in thousands)	Fair value		Level 1		Level 2		Level 3
Assets
Money market funds	$	58,127	$	58,127	$	—	$	—
Marketable securities:
U.S. treasury bills and notes		277,341		—		277,341		—
U.S. agency securities		18,771		—		18,771		—
Total assets	$	354,239	$	58,127	$	296,112	$	—
Liabilities
Success payment liability	$	4,371	$	—	$	—	$	4,371
Total liabilities	$	4,371	$	—	$	—	$	4,371

Cash Equivalents—Cash equivalents of $105.3 million and $58.1 million as of December 31, 2022 and 2021, 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.

Antidilution Rights—This 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 IPO in June 2021. Refer to Note 5, Fair value of financial instruments, for additional discussion.

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 high nine-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 payments 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 increases of $1.5 million, $7.8 million and $2.4 million recorded to other expense for the years ended December 31, 2022, 2021 and 2020, respectively.

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, an initial public offering, or a company sale at December 31, 2022, 2021 and 2020, were as follows:


	At December 31, 2022			At December 31, 2021			At December 31, 2020
Fair value of common stock (per share)	$	19.35		$	36.87		$	8.24
Equity volatility		84	%		77	%		105	%
Cumulative probability of triggering event	n/a			n/a				70	%
Expected term (in years)	n/a			n/a				0.50

At December 31, 2020 the fair value of the Company's common stock was determined by management with the assistance of an independent third-party valuation specialist using methods consistent with the AICPA Valuation Guide. The computation of equity volatility was estimated using available information about the historical volatility of stocks of similar publicly traded companies for a period matching the expected term assumption. In addition, the Company incorporated the timing and probability of future events in the calculation of liabilities. The Company applied a 90% probability of termination of the Broad License Agreement at December 31, 2020.

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)	Antidilution rights liability			Success payment liability			Total
Balance at December 31, 2020	$	6,916		$	2,806		$	9,722
Issuance of Series A Preferred		(32,490	)		—			(32,490	)
Issuance of common stock		—			(6,250	)		(6,250	)
Change in fair value		25,574			7,815			33,389
Balance at December 31, 2021	$	—		$	4,371		$	4,371
Change in fair value		—			(1,486	)		(1,486	)
Balance at December 31, 2022	$	—		$	2,885		$	2,885

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accrued expenses

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

Accrued Expenses

6. Accrued expenses

Accrued expenses consist of the following:


	December 31,
(in thousands)	2022		2021
Employee compensation and related benefits	$	9,124	$	6,050
Accrued external research and development expenses		8,919		5,041
Professional fees		1,193		1,109
License and milestone payments		310
Other		1,221		792
Total	$	20,767	$	12,992

Leases

12 Months Ended

Dec. 31, 2022

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, 2022		December 31, 2021
Operating lease costs	$	5,946	$	1,923
Variable lease costs		1,601		747
Short term lease costs		698		2,278
Total	$	8,245	$	4,948

Supplemental cash flow information related to operating leases was as follows:


(in thousands)	December 31, 2022		December 31, 2021
Cash paid for amounts included in the measurements of lease liabilities:
Operating cash flows related to operating leases	$	5,050	$	2,021

As of December 31, 2022, 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 10 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 the Boston Lease upon customary events of default.

In July 2022 the Company notified its landlord under its prior lease of its intent to terminate that lease prior to the expiration of the term lease. As of December 31, 2022, there was no remaining ROU and lease liability for the prior lease.

In October 2021, the Company entered into a sublease for 11,931 square feet of office and laboratory space in Cambridge, Massachusetts. The sublease commenced in December 2021 and has an initial noncancelable term of 12 months. The Company had the option to extend the sublease for one extension term of three months by written notice not less than six months prior to the expiration of the sublease term. The Company did not exercise this option. Therefore, this sublease is treated as a short-term lease. The total fixed lease payments over the sublease term were approximately $1.4 million and the Company was also required to pay its proportional share of operating expenses.

Future minimum commitments under non-cancellable leases as of December 31, 2022 were as follows:


Years ending December 31,	Amount
	(in thousands)
2023	$	12,306
2024		10,563
2025		10,868
2026		11,183
2027		11,506
Thereafter		62,736
Total lease payments	$	119,162
Less: interest		(37,245	)
Present value of operating lease liabilities	$	81,917

License Agreements

12 Months Ended

Dec. 31, 2022

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.

Indemnification agreements

In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, contract research organizations, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. The Company has not incurred any material costs as a result of such indemnifications and is not currently aware of any indemnification claims.

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 each of 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 remain payable as of December 31, 2022 and will be settled in cash. 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. Pursuant to the Beam Agreement, the Company received an exclusive, worldwide, sublicensable license under certain of Beam’s base editing technology, 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, or Cas12b technology, in each case, directed to any of four initial gene targets, including the PCSK9 and ANGPTL3 genes, that are associated with an increased risk of coronary diseases. In addition, the Company granted Beam an exclusive, worldwide, sublicensable license under certain of its delivery technology to develop, manufacture, sell and import product candidates and products, except for base editor products licensed to Verve.

Both parties may conduct certain activities in accordance with an agreed-upon research and/or development plan. Following the dosing of a final patient in a Phase 1b clinical trial of a given licensed product for the initial gene targets, Beam has the right to opt in to share 33% of worldwide expenses of the development of such licensed product, as well as jointly commercialize and share profits and expenses of commercializing such licensed

product in the United States on a 50/50 basis. If Beam exercises its opt-in right for a given licensed product for the initial gene targets, which we refer to following such opt-in as 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. The term of the Beam Agreement continues until the last to expire of any royalty term for any product. The Company has the right to terminate the Beam Agreement as to any licensed product, but not for any collaboration product, by delivering a 90-day termination notice to Beam, provided that Beam has elected not to exercise its opt-in right or the period to exercise such opt-in right has expired.

The Company is responsible for all costs and expenses incurred in the conduct of activities under the research plan, any development plan and any costs and expenses for the development of a licensed product for which Beam has not elected to opt-in.

As partial consideration for the license rights granted by Beam under the Beam Agreement, the Company paid a one-time, nonrefundable fee through issuing 276,075 shares of its common stock with a fair value of $0.3 million. To the extent achieved, for each licensed product, the Company is also obligated to pay up to $11.3 million in development and regulatory-based milestones and $15.0 million in sales-based milestones. To the extent there are sales of a licensed product, the Company is required to pay low-to-mid single digit royalties on net sales. To the extent achieved, for each collaboration product outside of the United States, the Company is obligated to pay up to $5.6 million in development and regulatory-based milestones and $7.5 million in sales-based milestones. To the extent there are ex-U.S. sales of a collaboration product, the Company is required to pay low-to-mid single digit royalties on net sales. Due to the submission of the Company's clinical trial application in New Zealand, a milestone payment of $0.3 million was triggered in 2022 and subsequently paid by the Company to Beam. Additionally, due to the first patient dosing with VERVE-101 in a clinical trial, a milestone payment of $0.2 million was triggered and paid by the Company to Beam.

The parties have also promised that in further consideration for the licenses granted under the parties’ respective delivery technologies, each party will pay to the other party development-based milestone payments up to $6.0 million for each delivery technology product of such paying party to achieve the corresponding milestone event. The triggering of these milestone payments was not considered probable as of the transaction date, and no expense has been recorded for these milestones as of December 31, 2022.

On July 5, 2022, the Company entered into an Amended and Restated Collaboration and License Agreement with Beam (the “Amended Beam Agreement”).

Pursuant to the Amended Beam Agreement, Beam granted the Company an exclusive, worldwide, sublicensable license under certain of Beam’s base editing technology to develop and commercialize products directed towards an additional liver-mediated, cardiovascular disease target. The Company is responsible for the development and commercialization of products targeting the additional gene target, subject to Beam’s opt-in right. Following the dosing of the final patient in a Phase 1b clinical trial of a licensed product for such additional gene target, Beam has the 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. If Beam does not elect to opt-in, Beam is entitled to receive milestones and royalties on the same basis as other collaboration products as provided in the Beam Agreement.

In exchange, the Company granted to 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.

The Amended Beam Agreement also clarified intellectual property rights with respect to the Company's GalNAc-LNP delivery technology; grants 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; terminates the Company's rights and economic obligations under the Beam Agreement with respect to the undisclosed genes, allowing the Company and Beam to independently develop and commercialize products directed to such gene targets; and concludes other licenses that applied under the Beam Agreement with respect to delivery and other technologies developed by the parties for the development and commercialization of base editor products.

To the extent there are sales of a delivery technology product, each party will pay the other party low-to-mid single digit royalties based on the annual aggregate worldwide net sales resulting from the sale of each delivery

technology product of such paying party; provided, however, that such royalty payments will not apply to net sales of the collaboration products or licensed products. The Company concluded the receipt of any milestone or royalty payments under the Amended Beam Agreement was not probable as of December 31, 2022.

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 recognized research and development expense of approximately $0.1 million during the year ended December 31, 2022, and $1.0 million for the year ended December 31, 2021, respectively, 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. Due 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.

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-201. As consideration for the license and rights granted under the agreement, the Company made 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. The milestones have not been achieved and no expense has been recorded for these milestones as of December 31, 2022.

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 make 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 Agreements

12 Months Ended

Dec. 31, 2022

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 the 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, the Company entered into a stock purchase agreement (the “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 (“Research Plan”). The research term has an initial term of four years and may be extended by Vertex for up to one additional year (“Research Term”). The Research Plan is overseen by a Joint Research Committee (“JRC”) as detailed in the Vertex Agreement. Any material amendments to the Research Plan are required to be mutually agreed to by the JRC.

During the 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 Research Plan in order to achieve certain development candidate criteria agreed to by the JRC. Following the 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 million and is eligible to receive (i) success payments of up to $22 million for each product candidate (up to a maximum of $66 million) that achieves the applicable development criteria, (ii) up to an aggregate of $175 million in development milestones and (iii) up to an aggregate of $165 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 of 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 ranging from $25 million to $70 million, 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.

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 Research Plan (the

“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 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 Research Plan. The Company utilized the most likely amount approach and estimated the expected cost reimbursement to be $5.8 million at inception. 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. As of December 31, 2022, the estimate of the expected reimbursement is $5.8 million based on expectations as of such date. 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 Research Services obligation will be allocated entirely to that obligation as the cost reimbursement relates specifically to the services being performed under the Research Plan. The reimbursement of 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) that 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 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 Research Services obligation will be 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 Research Term.

During the year ended December 31, 2022, the Company recognized $1.9 million of revenue associated with the Vertex Agreement related to research services performed during the period. As of December 31, 2022, the Company has recorded $20.0 million as non-current deferred revenue.

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, 2022.

Preferred and Common Stock

12 Months Ended

Dec. 31, 2022

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. During the year ended December 31, 2022, the Company sold 1,280,168 shares of its common stock under the Sales Agreement for aggregate net proceeds of $42.9 million, after deducting commissions and offering expenses payable by the Company.

The holders of common stock are entitled to one vote for each share of common stock.

Stock-based compensation

12 Months Ended

Dec. 31, 2022

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, 2022 the Company had reserved 7,057,629 shares of the Company's common stock for issuance of stock options, restricted stock, and restricted stock units, of which 3,025,807 remained outstanding for future grant under the 2021 Plan. On January 1, 2023, 3,086,541 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 December 31,
(in thousands)	2022		2021		2020
Research and development	$	12,486	$	3,830	$	494
General and administrative		9,991		3,242		356
Total stock-based compensation expense	$	22,477	$	7,072	$	850

Stock options

The assumptions used in Black-Scholes for stock options granted were as follows:


	Year ended December 31,
	2022			2021			2020
Expected volatility		77.3	%		77.7	%		84.8	%
Weighted-average risk-free interest rate		2.4	%		0.9	%		0.4	%
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, 2022:


	Number of options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate intrinsic value(2) (in thousands)
Outstanding at December 31, 2021		6,119,295		$	9.44
Granted		2,561,300		$	28.49
Exercised		(743,638	)	$	2.92
Forfeited		(324,131	)	$	20.37
Outstanding at December 31, 2022		7,612,826		$	16.10		8.3	$	63,790
Exercisable at December 31, 2022		2,551,841		$	7.52		7.6	$	34,295
Expected to vest after December 31, 2022(1)		5,060,985		$	20.43		8.6	$	29,495

(1)

This represents the number of unvested options outstanding as of December 31, 2022 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, 2022.

During the year ended December 31, 2022 the weighted average grant date fair value of the stock options granted was $19.39 per share. The aggregate intrinsic value of stock options exercised during the year ended December 31, 2022 was approximately $21.2 million while the Company received $2.2 million in proceeds for the exercise of these options.

As of December 31, 2022, there was $64.4 million of unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted-average period of approximately 2.5 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, 2022, the Company granted 688,700 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, 2022 was as follows:


	Shares				Weighted- average grant date fair value per share
Unvested restricted stock units as of December 31, 2021		32,000		$		36.58
Restricted stock units granted		688,700		$		22.65
Restricted stock units vested		(6,375	)	$		35.53
Restricted stock units forfeited		(36,500	)	$		24.32
Unvested restricted stock units as of December 31, 2022		677,825		$		23.10

At December 31, 2022, there was $13.6 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 3.5 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, or 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, 2022, 134,107 shares had been purchased by employees under the ESPP and 784,326 shares remained available for issuance under the ESPP. On January 1, 2023, 617,308 shares of common stock were added to the amount reserved for sale under the ESPP.

Net Loss Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

12. Net loss per share attributable to common stockholders

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company:


	Year ended December 31,
(in thousands, except share and per share amounts)	2022			2021			2020
Numerator:
Net loss attributable to common stockholders	$	(157,387	)	$	(120,314	)	$	(45,704	)
Denominator:
Weighted average number of common shares, basic and diluted		54,023,653			26,872,036			2,250,093
Net loss per common share attributable to common stockholders, basic and diluted	$	(2.91	)	$	(4.48	)	$	(20.31	)

The Company’s potential dilutive securities, which include convertible preferred stock, 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 attributable to common stockholders for the period indicated because including them would have had an anti-dilutive effect:


	Year ended December 31,
	2022		2021		2020
Convertible preferred stock		—		—		19,387,544
Unvested restricted stock		—		—		537,633
Unvested restricted stock units		677,825		32,000		—
Outstanding options to purchase common stock		7,612,826		6,119,295		3,888,823
Total		8,290,651		6,151,295		23,814,000

As part of the license agreements with Harvard and Broad, the Company is required to make success payments. The Company may elect to make these payments by issuing shares of the Company's common stock. As of December 31, 2022, an aggregate of $6.3 million was earned relating to these success payments, which the Company settled in cash in November 2021. No success payments were triggered or paid during the year ended December 31, 2022.

Income Taxes

12 Months Ended

Dec. 31, 2022

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 $157.4 million, $120.3 million and $45.7 million for the years ended December 31, 2022, 2021, and 2020, respectively.

Income tax expense (benefit) is summarized as follows:


	Year ended December 31,
(in thousands)	2022		2021		2020
Current:
Federal	$	-	$	-	$	-
State		53		-		-
Foreign		-		-		-
Total current provision	$	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)	2022			2021			2020
Federal statutory rate		21.0	%		21.0	%		21.0	%
Change in valuation allowance		(34.7	)%		(31.3	)%		(29.6	)%
Stock-based compensation		(0.3	)%		0.9	%		(0.3	)%
Executive compensation		(0.8	)%		(1.1	)%		0.0	%
Permanent items		(0.2	)%		(0.1	)%		1.1	%
State income taxes, net of federal benefit		8.4	%		6.1	%		6.8	%
Research and development tax credits		5.6	%		4.5	%		1.0	%
Other		1.0	%		0.0	%		0.0	%
Effective income tax rate		—	%		—	%		—	%

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, 2022 and 2021 are comprised of the following:


	December 31,
(in thousands)	2022			2021
Deferred tax assets:
Net operating loss carryforwards	$	43,779		$	33,409
Capitalized costs—net of amortization		11,095			12,395
Research and development tax credits		20,835			6,098
Capitalized research costs		28,650			—
Stock-based compensation		3,669			1,117
Other		174			76
Lease liability		22,285			533
Accrued expenses		5,024			2,852
Total deferred tax assets		135,511			56,480
Deferred tax liabilities:
Property and equipment		(881	)		(899	)
Right of use asset		(24,994	)		(501	)
Total deferred tax liabilities		(25,875	)		(1,400	)
Total deferred tax assets, net		109,636			55,080
Less: valuation allowance		(109,636	)		(55,080	)
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, 2022 and 2021. The valuation allowance increased by $54.6 million in 2022, 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, 2022, 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, 2022, the Company had approximately $163.9 million of federal and $148.0 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 at various dates through 2042. Additionally, as of December 31, 2022, the Company had approximately $14.4 million of federal and $8.2 million of Massachusetts tax research and development credits that expire starting in 2042 and 2037, respectively.

As of December 31, 2022 and 2021, 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 not 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, and Wisconsin. 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.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Related Party Transactions

12 Months Ended

Dec. 31, 2022

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 years ended December 31, 2022 and 2021, respectively, the Company recognized $0.4 million and $0.2 million as a reduction to research and development expense related to reimbursements received for materials sold to Beam.

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.

An executive of Broad was a board member of the Company. The board member resigned, effective May 2021. In March 2019, the Company simultaneously entered into the Harvard/Broad License Agreement and Broad License Agreement 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. Additional consideration under the license agreements include antidilution rights and success payments. See Note 8, License agreements.

Employee Benefit Plans

12 Months Ended

Dec. 31, 2022

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 statutorily prescribed limit, equal to $20,500 in 2022 with a catch up contribution limit equal to $6,500 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 contributions by the Company to the 401(k) plan were $1.0 million, $0.4 million, and $0.1 million for the years ended December 31, 2022, 2021, and 2020, respectively.

Subsequent Events

12 Months Ended

Dec. 31, 2022

Subsequent Events [Abstract]

Subsequent Events

16. Subsequent events

The Company evaluated all subsequent events and determined there are no material recognized or unrecognized subsequent events requiring disclosure.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Principles of Consolidation

Principles of consolidation

Use of Estimates

Use of estimates

Cash and Cash Equivalents

Cash and cash equivalents

Restricted cash


	December 31,
(in thousands)	2022		2021
Cash and cash equivalents	$	115,412	$	64,330
Restricted cash		4,824		5,237
Total cash, cash equivalents and restricted cash	$	120,236	$	69,567

Marketable Securities

Marketable securities

Concentration of Credit Risk

Concentrations of credit risk

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

Fair Value of Financial Instruments

Fair value of financial instruments

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.

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

Impairment of Long-Lived Assets

Impairment of long-lived assets

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.

Revenue Recognition

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.

Research and Development Costs

Research and development costs

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.

Income taxes

Comprehensive loss

Net loss per share

anti-dilutive. The Company reported a net loss attributable to common stockholders for the years ended December 31, 2022, 2021 and 2020.

Segment and Geographic Information

Segment and geographic information

Subsequent Events

Subsequent events

Recently Adopted and Issued Accounting Pronouncements

Recently issued accounting pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

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)	2022		2021
Cash and cash equivalents	$	115,412	$	64,330
Restricted cash		4,824		5,237
Total cash, cash equivalents and restricted cash	$	120,236	$	69,567

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)

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Schedule of Marketable Securities

Marketable securities by security type consisted of the following:


	December 31, 2022
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
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


	December 31, 2021
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. treasury bills and notes	$	277,559	$	—	$	(218	)	$	277,341
U.S. agency securities		18,781		—		(10	)		18,771
Total	$	296,340	$	—	$	(228	)	$	296,112

The remaining contractual maturities of all marketable securities were less than 18 months as of December 31, 2022 and 2021.

Property and equipment, net (Table)

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, net

Property and equipment, net, consist of the following:


	December 31,
(in thousands)	2022			2021
Lab equipment		20,379		$	8,567
Leasehold improvements		266			266
Furniture and fixtures		2,294			566
Computer equipment		826			158
Total property and equipment		23,765			9,557
Less accumulated depreciation		(4,987	)		(2,333	)
Property and equipment, net	$	18,778		$	7,224

Schedule of Depreciation Expense


	Year ended December 31,
(in thousands)	2022		2021		2020
Depreciation expense	$	2,804	$	1,535	$	1,328

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2022

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, 2022
(in thousands)	Fair value		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


	As of December 31, 2021
(in thousands)	Fair value		Level 1		Level 2		Level 3
Assets
Money market funds	$	58,127	$	58,127	$	—	$	—
Marketable securities:
U.S. treasury bills and notes		277,341		—		277,341		—
U.S. agency securities		18,771		—		18,771		—
Total assets	$	354,239	$	58,127	$	296,112	$	—
Liabilities
Success payment liability	$	4,371	$	—	$	—	$	4,371
Total liabilities	$	4,371	$	—	$	—	$	4,371

Schedule of Fair Value Liabilities Measured on Recurring Basis


	At December 31, 2022			At December 31, 2021			At December 31, 2020
Fair value of common stock (per share)	$	19.35		$	36.87		$	8.24
Equity volatility		84	%		77	%		105	%
Cumulative probability of triggering event	n/a			n/a				70	%
Expected term (in years)	n/a			n/a				0.50

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)	Antidilution rights liability			Success payment liability			Total
Balance at December 31, 2020	$	6,916		$	2,806		$	9,722
Issuance of Series A Preferred		(32,490	)		—			(32,490	)
Issuance of common stock		—			(6,250	)		(6,250	)
Change in fair value		25,574			7,815			33,389
Balance at December 31, 2021	$	—		$	4,371		$	4,371
Change in fair value		—			(1,486	)		(1,486	)
Balance at December 31, 2022	$	—		$	2,885		$	2,885

Accrued expenses (Tables)

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following:


	December 31,
(in thousands)	2022		2021
Employee compensation and related benefits	$	9,124	$	6,050
Accrued external research and development expenses		8,919		5,041
Professional fees		1,193		1,109
License and milestone payments		310
Other		1,221		792
Total	$	20,767	$	12,992

Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Components of Operating Lease Cost

The components of operating lease cost were as follows:


(in thousands)	December 31, 2022		December 31, 2021
Operating lease costs	$	5,946	$	1,923
Variable lease costs		1,601		747
Short term lease costs		698		2,278
Total	$	8,245	$	4,948

Supplemental Cash Flow Information Related to Operating Leases

Supplemental cash flow information related to operating leases was as follows:


(in thousands)	December 31, 2022		December 31, 2021
Cash paid for amounts included in the measurements of lease liabilities:
Operating cash flows related to operating leases	$	5,050	$	2,021

Schedule of Future Minimum Lease Commitments under Non-Cancellable Leases

Future minimum commitments under non-cancellable leases as of December 31, 2022 were as follows:


Years ending December 31,	Amount
	(in thousands)
2023	$	12,306
2024		10,563
2025		10,868
2026		11,183
2027		11,506
Thereafter		62,736
Total lease payments	$	119,162
Less: interest		(37,245	)
Present value of operating lease liabilities	$	81,917

Collaboration and License Agreements (Tables)

12 Months Ended

Dec. 31, 2022

Collaboration and License Agreements [Abstract]

Schedule of transaction price separate performance obligations

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 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

Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2022

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 December 31,
(in thousands)	2022		2021		2020
Research and development	$	12,486	$	3,830	$	494
General and administrative		9,991		3,242		356
Total stock-based compensation expense	$	22,477	$	7,072	$	850

Schedule of Assumptions Used for Options Granted

The assumptions used in Black-Scholes for stock options granted were as follows:


	Year ended December 31,
	2022			2021			2020
Expected volatility		77.3	%		77.7	%		84.8	%
Weighted-average risk-free interest rate		2.4	%		0.9	%		0.4	%
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, 2022:


	Number of options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate intrinsic value(2) (in thousands)
Outstanding at December 31, 2021		6,119,295		$	9.44
Granted		2,561,300		$	28.49
Exercised		(743,638	)	$	2.92
Forfeited		(324,131	)	$	20.37
Outstanding at December 31, 2022		7,612,826		$	16.10		8.3	$	63,790
Exercisable at December 31, 2022		2,551,841		$	7.52		7.6	$	34,295
Expected to vest after December 31, 2022(1)		5,060,985		$	20.43		8.6	$	29,495

(1)

This represents the number of unvested options outstanding as of December 31, 2022 that are expected to vest in the future.

(2)

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, 2022 was as follows:


	Shares				Weighted- average grant date fair value per share
Unvested restricted stock units as of December 31, 2021		32,000		$		36.58
Restricted stock units granted		688,700		$		22.65
Restricted stock units vested		(6,375	)	$		35.53
Restricted stock units forfeited		(36,500	)	$		24.32
Unvested restricted stock units as of December 31, 2022		677,825		$		23.10

Net Loss Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2022

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 attributable to common stockholders of the Company:


	Year ended December 31,
(in thousands, except share and per share amounts)	2022			2021			2020
Numerator:
Net loss attributable to common stockholders	$	(157,387	)	$	(120,314	)	$	(45,704	)
Denominator:
Weighted average number of common shares, basic and diluted		54,023,653			26,872,036			2,250,093
Net loss per common share attributable to common stockholders, basic and diluted	$	(2.91	)	$	(4.48	)	$	(20.31	)

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 attributable to common stockholders for the period indicated because including them would have had an anti-dilutive effect:


	Year ended December 31,
	2022		2021		2020
Convertible preferred stock		—		—		19,387,544
Unvested restricted stock		—		—		537,633
Unvested restricted stock units		677,825		32,000		—
Outstanding options to purchase common stock		7,612,826		6,119,295		3,888,823
Total		8,290,651		6,151,295		23,814,000

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Summary of Income Tax Expense (Benefit)

Income tax expense (benefit) is summarized as follows:


	Year ended December 31,
(in thousands)	2022		2021		2020
Current:
Federal	$	-	$	-	$	-
State		53		-		-
Foreign		-		-		-
Total current provision	$	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)	2022			2021			2020
Federal statutory rate		21.0	%		21.0	%		21.0	%
Change in valuation allowance		(34.7	)%		(31.3	)%		(29.6	)%
Stock-based compensation		(0.3	)%		0.9	%		(0.3	)%
Executive compensation		(0.8	)%		(1.1	)%		0.0	%
Permanent items		(0.2	)%		(0.1	)%		1.1	%
State income taxes, net of federal benefit		8.4	%		6.1	%		6.8	%
Research and development tax credits		5.6	%		4.5	%		1.0	%
Other		1.0	%		0.0	%		0.0	%
Effective income tax rate		—	%		—	%		—	%

Schedule of Deferred Taxes


	December 31,
(in thousands)	2022			2021
Deferred tax assets:
Net operating loss carryforwards	$	43,779		$	33,409
Capitalized costs—net of amortization		11,095			12,395
Research and development tax credits		20,835			6,098
Capitalized research costs		28,650			—
Stock-based compensation		3,669			1,117
Other		174			76
Lease liability		22,285			533
Accrued expenses		5,024			2,852
Total deferred tax assets		135,511			56,480
Deferred tax liabilities:
Property and equipment		(881	)		(899	)
Right of use asset		(24,994	)		(501	)
Total deferred tax liabilities		(25,875	)		(1,400	)
Total deferred tax assets, net		109,636			55,080
Less: valuation allowance		(109,636	)		(55,080	)
Deferred tax assets, net of valuation allowance	$	—		$	—

Nature of the Business and Basis of Presentation - Additional Information (Details) $ in Millions	Dec. 31, 2022 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash, cash equivalents, and marketable securities	$ 554.8

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 115,412	$ 64,330
Restricted cash	4,824	5,237
Total cash, cash equivalents and restricted cash	$ 120,236	$ 69,567	$ 9,456	$ 3,221

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2021 shares
Summary Of Significant Accounting Policies [Line Items]
Impairment losses	$ 0	$ 0	$ 0
Percentage of tax benefit realized	50.00%
Number of operating segment \| Segment	1
Present value of operating lease liabilities	$ 81,917,000
Operating lease right-of-use assets	91,877,000	1,839,000
Operating Lease, Right-of-Use Asset	91,877,000	1,839,000
Operating Lease, Liability	81,917,000
ASC 842
Summary Of Significant Accounting Policies [Line Items]
Present value of operating lease liabilities	2,600,000
Operating lease right-of-use assets	2,400,000
Operating Lease, Right-of-Use Asset	2,400,000
Operating Lease, Liability	2,600,000
Harvard and Board
Summary Of Significant Accounting Policies [Line Items]
Success payment liability, payable	$ 10,000,000,000.0	10,000,000,000.0
Issuance of Additional Common Stock \| shares				878,098
Success Liability Payment		$ 6,300,000

Summary of Significant Accounting Policies - Schedule of Property and Equipment Estimated Useful Life (Details)	12 Months Ended
	Dec. 31, 2022
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]
Property and equipment estimated useful life	Shorter of useful life or remaining lease term

Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current [Abstract]
Debt Securities, Available-for-Sale, Amortized Cost, Current	$ 440,090	$ 296,340
Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Current	81	0
Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Current	(775)	(228)
Debt Securities, Available-for-Sale, Current	439,396	296,112
U.S. Treasury Bills and Notes [Member]
Current [Abstract]
Debt Securities, Available-for-Sale, Amortized Cost, Current	228,432	277,559
Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Current	13	0
Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Current	(301)	(218)
Debt Securities, Available-for-Sale, Current	228,144	277,341
U.S. Agency Securities [Member]
Current [Abstract]
Debt Securities, Available-for-Sale, Amortized Cost, Current	211,658	18,781
Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Current	68	0
Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Current	(474)	(10)
Debt Securities, Available-for-Sale, Current	$ 211,252	$ 18,771

Marketable securities - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Remaining contractual maturities of marketable securities term	12 months	12 months
Unrealized losses on marketable securities	$ 0.8	$ 0.2

Property and equipment, net - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Total property and equipment	$ 23,765	$ 9,557
Less accumulated depreciation	(4,987)	(2,333)
Property and equipment, net	18,778	7,224
Lab equipment
Property Plant And Equipment [Line Items]
Total property and equipment	20,379	8,567
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	266	266
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	2,294	566
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 826	$ 158

Property and equipment, net - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 2,804	$ 1,535	$ 1,328

Property and equipment, net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation	$ 2,804	$ 1,535	$ 1,328

Fair value of financial instruments - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets
Total assets	$ 544,699	$ 354,239
Liabilities
Total liabilities	2,885	4,371
Money Market Funds
Assets
Total assets	105,303	58,127
U.S. Treasury Bills and Notes
Assets
Total assets	228,144	277,341
U.S. Agency Securities
Assets
Total assets	211,252	18,771
Success Payment Liability
Liabilities
Total liabilities	2,885	4,371
Level 1
Assets
Total assets	105,303	58,127
Liabilities
Total liabilities	0	0
Level 1 \| Money Market Funds
Assets
Total assets	105,303	58,127
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	439,396	296,112
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	228,144	277,341
Level 2 \| U.S. Agency Securities
Assets
Total assets	211,252	18,771
Level 2 \| Success Payment Liability
Liabilities
Total liabilities	0	0
Level 3
Assets
Total assets	0	0
Liabilities
Total liabilities	2,885	4,371
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	$ 2,885	$ 4,371

Fair value of financial instruments - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021	Jun. 30, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 105,300	$ 58,100
Common Stock, Shares Issued	61,730,816	48,511,735			878,098
Issuance of common stock, value	$ 62	$ 49
Harvard and Board
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, payable	$ 10,000,000	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
Fair value inputs probability of termination			90.00%
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	$ 1,500	$ 7,800	$ 2,400

Fair value of financial instruments - Schedule of Fair Value Liabilities Measured on Recurring Basis (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of common stock (per share)	$ 19.35	$ 36.87	$ 8.24
Cumulative probability of triggering event			70.00%
Equity Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity volatility	84.00%	77.00%	105.00%
Expected Term
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Expected term (in years)			6 months

Fair value of financial instruments - Schedule of Reconciliation of Changes in Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 4,371	$ 9,722
Issuance of Series A Preferred		(32,490)
Issuance of common stock		(6,250)
Changes in fair value	$ 1,486	$ 33,389
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Change In Fair Value Of Success Payments Liabilities	Change In Fair Value Of Success Payments Liabilities
Ending balance	$ 2,885	$ 4,371
Antidilution Rights Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	0	6,916
Issuance of Series A Preferred		(32,490)
Issuance of common stock		(0)
Changes in fair value	0	25,574
Ending balance	0	0
Success Payment Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	4,371	2,806
Issuance of Series A Preferred		0
Issuance of common stock		6,250
Changes in fair value	1,486	7,815
Ending balance	$ 2,885	$ 4,371

Accrued expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Employee compensation and related benefits	$ 9,124	$ 6,050
Accrued external research and development expenses	8,919	5,041
Professional fees	1,193	1,109
License and milestone payments	310
Other	1,221	792
Total	$ 20,767	$ 12,992

Leases - Additional Information (Details) $ in Thousands		1 Months Ended		12 Months Ended
Leases - Additional Information (Details) $ in Thousands	Aug. 19, 2021 USD ($) ft²	Aug. 31, 2022 USD ($)	Oct. 31, 2021 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jan. 31, 2022 ft²
Lessee Lease Description [Line Items]
Lease commencement date			2021-12
Lease noncancelable term			12 months
Lessee, operating lease, option to extend			The Company had the option to extend the sublease for one extension term of three months by written notice not less than six months prior to the expiration of the sublease term. The Company did not exercise this option.
Increase in Right-Of-Use assets		$ 91,800
Increase in operating lease liability		$ 80,800		$ (3,011)	$ (1,940)	$ 0
Present value of operating lease liabilities				81,917
Operating lease right-of-use assets				$ 91,877	1,839
Operating lease incremental borrowing rate				7.89%
Weighted average remaining lease term				10 years
Operating lease payments				$ 5,050	2,021
Short term lease costs				698	$ 2,278
New Amendment
Lessee Lease Description [Line Items]
Lease area \| ft²							105,182
Additional Lease Area \| ft²							249
ASC 842
Lessee Lease Description [Line Items]
Present value of operating lease liabilities				2,600
Operating lease right-of-use assets				2,400
Premises
Lessee Lease Description [Line Items]
Lease area \| ft²	104,933		11,931
Lease not yet commenced, lease term	10 years
Option to extend, lease not yet commenced	five years
Tenant improvements allowance	$ 21,000
Operating lease payments			$ 1,400
Prepaid rent				$ 800
Increase decrease in rent				3.00%
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 of Operating Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Lease, Cost [Abstract]
Operating lease costs	$ 5,946	$ 1,923
Variable lease costs	1,601	747
Short term lease costs	698	2,278
Total	$ 8,245	$ 4,948

Leases - Summary of Supplemental Cash Flow Information Related to Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash paid for amounts included in the measurements of lease liabilities [Abstract]
Operating cash flows related to operating leases	$ 5,050	$ 2,021

Leases - Summary of Future Minimum Commitments under Non-Cancellable Operating Leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Lessee, Operating Lease, Liability, to be Paid [Abstract]
2023	$ 12,306
2024	10,563
2025	10,868
2026	11,183
2027	11,506
Thereafter	62,736
Total lease payments	119,162
Less: interest	(37,245)
Present value of operating lease liabilities	$ 81,917

License Agreements - Additional Information (Details) - USD ($)		1 Months Ended	10 Months Ended	12 Months Ended
	Jul. 05, 2022	Apr. 30, 2019	Oct. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021
Research And Development Arrangement Contract To Perform For Others [Line Items]
Common stock, shares issued				61,730,816	48,511,735					878,098
Issuance of common stock				$ 242,826,000	$ 281,584,000
Issuance of common stock, value				$ 62,000	49,000
Derivative Liability, Statement of Financial Position [Extensible Enumeration]				Nonoperating Income (Expense)
Research and development expense				$ 130,095,000	$ 68,202,000	$ 35,371,000
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					$ 6,300,000			$ 300	$ 6,300,000
Beam 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
Payment of milestone development		11,300,000
Payment of sales based milestone		$ 15,000,000.0
Commercializing Profits And Expenses	35.00%
Percentage Shares of Development Expense	35.00%	33.00%
Milestone related expenses					0
Beam License Agreement \| Delivery Technology Product
Research And Development Arrangement Contract To Perform For Others [Line Items]
Payment of milestone development		$ 6,000,000.0
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				35,000,000.0
Milestone related expenses				0
Non Refundable Upfront License Fee				2,800,000
Clinical And Regulatory Milestone				10,000,000.0
Acuitas Agreements
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development expense				100,000	$ 1,000,000.0
License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Non Refundable Upfront License Fee			$ 2,000,000.0
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 Agreements (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Jul. 31, 2022	Jul. 18, 2022	Dec. 31, 2022	Sep. 30, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payments to Acquire Commercial Real Estate	$ 165.0
Three Licensed Agent [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Fixed consideration amount			$ 20.0
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
Aggregate purchase price	$ 35.0
Non Refundable Upfront Payment	25.0
Success payments for each product	22.0
Payments to Acquire Commercial Real Estate	175.0
Maximum percentage of profit/cost share		40.00%
Deferred Revenue, Revenue Recognized			1.9
Amount of Deferred Costs Related to Long-Term Contracts			$ 20.0
Vertex Agreement [Member] \| Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Success payments for each product	$ 66.0
Required fee payments		$ 70.0
Vertex Agreement [Member] \| Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum percentage of profit/cost share		60.00%
Required fee payments		$ 25.0
Vertex Agreement [Member] \| Stock Purchase Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Fixed transaction price		20.0
Fixed transaction price consisting upfront fee		25.0
Upfront fee discount		$ 5.0
Shares issued and sold		1,519,756
Estimated expected cost reimbursement		$ 5.8		$ 5.8

Collaboration and License Agreements - Schedule of transaction price separate performance obligations (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Performance obligation	$ 25,845
Research services obligation [Member]
Performance obligation	5,845
First licensed agent material right [Member]
Performance obligation	6,667
Second licensed agent material right [Member]
Performance obligation	6,667
Third licensed agent material right [Member]
Performance obligation	$ 6,666

Preferred Stock Tranche Liability - Additional Information (Details) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
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 - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jul. 31, 2022	Jun. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares issued			0	0
Preferred stock, value per share			$ 0.001	$ 0.001
Proceeds from issuance of Preferred Stock, net			$ 0	$ 93,759	$ 92,616
Preferred stock, shares authorized			5,000,000	5,000,000
Common stock, shares authorized			200,000,000	200,000,000
Common Stock, Shares Issued		878,098	61,730,816	48,511,735
Common stock, par value			$ 0.001	$ 0.001
Sales Agreement [Member]
Subsidiary Sale Of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction			1,280,168
Commission On Aggregate Gross Sale Proceeds	3.00%
Sale of Stock, Consideration Received on Transaction			$ 42,900
IPO
Subsidiary Sale Of Stock [Line Items]
Proceeds from issuance of Preferred Stock, net			$ 281,600
Additional shares of common stock		2,105,368
Public Offering Price		$ 19.00
Proceeds from common stock, gross		$ 306,700
Shares issued upon conversion of preferred stock			27,720,923
Stock Purchase Agreement [Member] \| Vertex Pharmaceuticals [Member]
Subsidiary Sale Of Stock [Line Items]
Common Stock, Shares Issued	1,519,756
Common stock, par value	$ 23.03
Agreegate Purchase Price	$ 35,000
Public offering [Member]
Subsidiary Sale Of Stock [Line Items]
Common Stock, Shares Issued	1,250,000
Sale of Stock, Number of Shares Issued in Transaction	9,583,334
Underwriting discounts and offering expenses	$ 15,800
Common Stock Offering Price Per Share	$ 27.00
Sale of Stock, Consideration Received on Transaction	$ 242,900
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
Stock Issued During Period, Shares, New Issues			9,583,334	16,141,157
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 - Additional Information (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) Instalment	Dec. 31, 2020 USD ($)	Dec. 31, 2018 shares	Jan. 01, 2023 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance	7,057,629
Proceeds from exercise of stock options \| $	$ 2,175	$ 966	$ 11
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	$ 19.39
Aggregate intrinsic value of stock options exercised \| $	$ 21,200
Proceeds from exercise of stock options \| $	2,200
Unrecognized stock-based compensation cost \| $	$ 64,400
Weighted average period over which unrecognized compensation is expected to be recognized	2 years 6 months
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period over which unrecognized compensation is expected to be recognized	6 months
Unrecognized stock-based compensation cost \| $	$ 13,600
Purchase of common stock under ESPP(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					3,086,541
Shares available for future grant	3,025,807
Purchase of common stock under ESPP(shares)	134,107
Stock available for issuance under ESPP	784,326
Number of RSUs, Granted	688,700
2021 Stock Incentive Plan \| Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grant	688,700
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					617,308

Stock-based compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 22,477	$ 7,072	$ 850
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	12,486	3,830	494
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 9,991	$ 3,242	$ 356

Stock-based compensation - Schedule of Assumptions Used for Options Granted (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Payment Arrangement [Abstract]
Expected volatility	77.30%	77.70%	84.80%
Weighted-average risk-free interest rate	2.40%	0.90%	0.40%
Expected dividend yield		0.00%
Expected term (in years)	6 years	6 years	6 years

Stock-based compensation - Schedule of Stock Option Activity (Details)
$ / shares in Units, $ in Thousands

12 Months Ended

Dec. 31, 2022

USD ($)

$ / shares

Share-Based Payment Arrangement [Abstract]

Number of options, Outstanding, Beginning balance | shares

6,119,295

Number of options, Granted | shares

2,561,300

Number of options, Exercised | shares

(743,638)

Number of options, Forfeited | shares

(324,131)

Number of options, Outstanding, Ending balance | shares

7,612,826

Number of options, Exercisable | shares

2,551,841

Number of options, Expected to vest | shares

5,060,985

^[1]

Weighted average exercise price, Beginning balance | $ / shares

$ 9.44

Weighted average exercise price, Granted | $ / shares

28.49

Weighted average exercise price, Exercised | $ / shares

2.92

Weighted average exercise price, Forfeited | $ / shares

20.37

Weighted average exercise price, Ending balance | $ / shares

16.10

Weighted average exercise price, Exercisable | $ / shares

7.52

Weighted average exercise price, Expected to vest | $ / shares

$ 20.43

^[1]

Weighted average remaining contractual life (in years), Outstanding

8 years 3 months 18 days

Weighted average remaining contractual life (in years), Exercisable

7 years 7 months 6 days

Weighted average remaining contractual life (in years), Expected to vest

8 years 7 months 6 days

^[1]

Aggregate intrinsic value, Outstanding | $

$ 63,790

^[2]

Aggregate intrinsic value, Exercisable | $

34,295

^[2]

Aggregate intrinsic value, Expected to vest | $

$ 29,495

^[1],[2]

[1]	This represents the number of unvested options outstanding as of December 31, 2022 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, 2022.

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, 2022 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unvested RSUs, beginning balance, Unvested \| shares	32,000
Number of RSUs, Granted \| shares	688,700
Unvested Restricted stock vested \| shares	(6,375)
Restricted stock units forfeited \| shares	(36,500)
Unvested RSUs, ending balance, Unvested \| shares	677,825
Weighted-Average Grant Date Fair Value Per Share, beginning balance, Unvested \| $ / shares	$ 36.58
Weighted-Average Grant-Date Fair Value, Granted \| $ / shares	22.65
Weighted-Average Grant Date Fair Value Per Share, Vested \| $ / shares	35.53
Weighted-Average Grant-Date Fair Value, forfeited \| $ / shares	24.32
Weighted-Average Grant Date Fair Value Per Share, ending balance, Unvested \| $ / shares	$ 23.10

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, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss attributable to common stockholders	$ (157,387)	$ (120,314)	$ (45,704)
Denominator:
Weighted average number of common shares, basic	54,023,653	26,872,036	2,250,093
Weighted average number of common shares, diluted	54,023,653	26,872,036	2,250,093
Net loss per common share attributable to common stockholders, basic	$ (2.91)	$ (4.48)	$ (20.31)
Net loss per common share attributable to common stockholders, diluted	$ (2.91)	$ (4.48)	$ (20.31)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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+ Details

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, 2022	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	8,290,651	6,151,295	23,814,000
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	0	0	19,387,544
Unvested Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	0	0	537,633
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	677,825	32,000	0
Outstanding Options To Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	7,612,826	6,119,295	3,888,823

Net Loss Per Share Attributable to Common Stockholders - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share Basic [Line Items]
Success payment liability	$ 2,885	$ 4,371
Harvard And Board \| License
Earnings Per Share Basic [Line Items]
Success payment liability	$ 6,300

Income taxes - Summary of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 0	$ 0	$ 0
State	53	0	0
Foreign	0	0	0
Total current provision	53	0	0
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	0	0	0
Total deferred provision	$ 0	$ 0	$ 0

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%	21.00%
Change in valuation allowance	(34.70%)	(31.30%)	(29.60%)
Stock-based compensation	0.30%	0.90%	(0.30%)
Executive compensation	(0.80%)	(1.10%)	0.00%
Permanent items	(0.20%)	(0.10%)	1.10%
State income taxes, net of federal benefit	8.40%	6.10%	6.80%
Research and development tax credits	5.60%	4.50%	1.00%
Other	1.00%	0.00%	0.00%
Total	0.00%	0.00%	0.00%

Income Taxes - Schedule of Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 43,779	$ 33,409
Capitalized costs—net of amortization	11,095	12,395
Research and development tax credits	20,835	6,098
Capitalized research costs	28,650
Stock-based compensation	3,669	1,117
Other	174	76
Lease liability	22,285	533
Accrued expenses	5,024	2,852
Total deferred tax assets	135,511	56,480
Deferred tax liabilities:
Property and equipment	(881)	(899)
Right of use asset	(24,994)	(501)
Total deferred tax liabilities	(25,875)	(1,400)
Total deferred tax assets, net	109,636	55,080
Less: valuation allowance	(109,636)	(55,080)
Deferred tax assets, net of valuation allowance	$ 0	$ 0

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	$ 53,000	$ 0	$ 0
Income (Loss) from Continuing Operations before Income Taxes, Domestic	157,400,000	120,300,000	$ 45,700,000
Deferred tax assets valuation allowance increase (decrease)	$ 54,600,000
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	163,900,000
Tax credit amount	$ 14,400,000
Tax credit carryforward expiration year	2042
State
Operating Loss Carryforwards [Line Items]
Percentage of future taxable income utilized to offset	80.00%
Net operating loss carryforwards	$ 148,000,000.0
Net operating loss carryforwards expiration year	2042
Massachusetts
Operating Loss Carryforwards [Line Items]
Tax credit amount	$ 8,200,000
Tax credit carryforward expiration year	2037

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Research and development expense	$ 130,095	$ 68,202	$ 35,371
Lease Rent Payment	1,800
Beam \| Materials Exchange Agreement \| Research and Development
Related Party Transaction [Line Items]
Research and development expense	$ 400	$ 200

Employee Benefit Plans - Additional Information (Details) - USD ($)		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, maximum annual contributions per employee, amount		$ 6,500
401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan employer matching contribution percent of match upto two percent of employee salary		2.00%
Defined contribution plan, maximum annual contributions per employee, amount		$ 20,500
Defined contribution plan, employer matching contribution, percent of match upto 3% of employee's salary	100.00%	3.00%
Defined contribution plan, employer matching contribution, percent of match after 3% and before 5% of employee's salary	50.00%
Defined contribution plan, employers matching contribution, annual vesting percentage	100.00%
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 $20,500 in 2022 with a catch up contribution limit equal to $6,500 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		$ 1,000,000.0	$ 400,000	$ 100,000