0001628280-23-007266 | 10-K | XBRL Viewer

$ 0

$ 5,210

Operating expenses:

General and administrative

^[1]

86,725

70,550

2,980

29,819

13,924

3,162

Total operating expenses

116,544

84,474

6,142

Loss from operations

(116,544)

(84,474)

(932)

Other income (expense):

Change in fair value of preferred stock tranche right liability

(74,319)

(10,904)

Change in fair value of anti-dilution obligation

(6,681)

(700)

Change in fair value of related party short-term investment

(8,128)

(391)

10,867

Other income (expense), net

^[2]

1,903

126

Total other expense, net

(6,225)

(81,379)

(611)

Net loss before income taxes

(122,769)

(165,853)

(1,543)

Provision for (benefit from) income taxes

(948)

(486)

1,867

Net loss

(121,821)

(165,367)

(3,410)

Accretion of preferred stock to redemption value

(1,468)

(1,645)

Cumulative dividend on preferred stock

(20,193)

(17,284)

Net loss attributable to common stockholders, basic

(142,014)

(184,119)

(5,055)

Net loss attributable to common stockholders, diluted

$ (142,014)

$ (184,119)

$ (5,055)

Net loss per share attributable to common stockholders, basic (in dollars per share)

$ (4.19)

$ (14.19)

$ (1.91)

Net loss per share attributable to common stockholders, diluted (in dollars per share)

$ (4.19)

$ (14.19)

$ (1.91)

Weighted-average common shares outstanding, diluted (in shares)

33,891,264

12,973,495

2,639,717

Weighted-average common shares outstanding, basic (in shares)

33,891,264

12,973,495

2,639,717

Comprehensive Loss:

Net loss

$ (121,821)

$ (165,367)

$ (3,410)

Change in unrealized losses on investments, net of tax

(357)

(27)

Total other comprehensive loss

(357)

(27)

Comprehensive Loss

$ (122,178)

$ (165,394)

$ (3,410)

[1]	Includes related party amounts of $150 and $42,170 for the years ended December 31, 2020 and 2021, respectively (see Note 14).
[2]	Includes related party amount of $126 for the year ended December 31, 2020 (see Note 14).

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Related party amounts, research and development	$ 42,170,000	$ 150,000
Related party amounts, other income		$ 126,000

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE AND CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($)	Total	Series A Redeemable Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Losses	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019		10,000,001	0
Beginning balance at Dec. 31, 2019		$ 3,987,000	$ 0
Temporary Equity [Abstract]
Issuance of redeemable convertible preferred stock for the settlement of the second tranche right liability, net of issuance costs (in shares)		34,999,999
Issuance of redeemable convertible preferred stock for the settlement of the second tranche right liability, net of issuance costs		$ 25,504,000
Accretion of preferred stock to redemption value	$ 1,645,000	$ 1,645,000
Ending balance (in shares) at Dec. 31, 2020		45,000,000	0
Ending balance at Dec. 31, 2020		$ 31,136,000	$ 0
Beginning balance (in shares) at Dec. 31, 2019				21,458,806
Beginning balance at Dec. 31, 2019	(2,598,000)			$ 0	$ 1,000	$ 0	$ (2,599,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of redeemable convertible preferred stock, including the settlement of the third and fourth tranche right liability, net of issuance costs	9,450,000				9,450,000
Accretion of redeemable convertible preferred stock to redemption value	(1,645,000)				(1,645,000)
Issuance of common stock as consideration for related party collaboration agreement (in shares)				1,608,337
Issuance of common stock as consideration for related party collaboration agreement	150,000				150,000
Issuance of restricted common stock (in shares)				5,422,456
Stock-based compensation expense	391,000				391,000
Net loss	(3,410,000)						(3,410,000)
Change in unrealized loss on investments, net of tax	0
Ending balance (in shares) at Dec. 31, 2020				28,489,599
Ending balance at Dec. 31, 2020	2,338,000			$ 0	8,347,000	0	(6,009,000)
Temporary Equity [Abstract]
Issuance of redeemable convertible preferred stock for the settlement of the second tranche right liability, net of issuance costs (in shares)		70,761,842	45,658,957
Issuance of redeemable convertible preferred stock for the settlement of the second tranche right liability, net of issuance costs		$ 71,719,000	$ 199,643,000
Reclassification of preferred stock tranche liability upon settlement		91,834,000
Accretion of preferred stock to redemption value	$ 1,468,000	$ 1,468,000
Ending balance (in shares) at Dec. 31, 2021	161,420,799	115,761,842	45,658,957
Ending balance at Dec. 31, 2021	$ 395,800,000	$ 196,157,000	$ 199,643,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of redeemable convertible preferred stock, including the settlement of the third and fourth tranche right liability, net of issuance costs	(998,000)				(998,000)
Accretion of redeemable convertible preferred stock to redemption value	(1,468,000)				(1,468,000)
Issuance of restricted common stock (in shares)				1,443,638
Issuance of common stock and settlement of the anti-dilution obligation (in shares)				2,498,850
Reclassification of the anti-dilution obligation upon settlement	7,536,000				7,536,000
Repurchase of unvested restricted common stock (in shares)				(18,227)
Stock-based compensation expense	1,746,000				1,746,000
Net loss	(165,367,000)						(165,367,000)
Change in unrealized loss on investments, net of tax	$ (27,000)					(27,000)
Ending balance (in shares) at Dec. 31, 2021	32,413,860			32,413,860
Ending balance at Dec. 31, 2021	$ (156,240,000)			$ 0	15,163,000	(27,000)	(171,376,000)
Temporary Equity [Abstract]
Accretion of preferred stock to redemption value	0
Conversion of convertible preferred stock to common stock upon closing of initial public offering (in shares)		(115,761,842)	(45,658,957)
Conversion of convertible preferred stock to common stock upon closing of initial public offering		$ (196,157,000)	$ (199,643,000)
Ending balance (in shares) at Dec. 31, 2022		0	0
Ending balance at Dec. 31, 2022		$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)				59,774
Issuance of common stock upon exercise of stock options	219,000				219,000
Reclassification of related party forward contract	12,020,000			$ 1,101,525	12,020,000
Conversion of convertible preferred stock to common stock upon closing of initial public offering (in shares)				51,923,758
Conversion of convertible preferred stock to common stock upon closing of initial public offering	395,801,000			$ 1,000	395,800,000
Issuance of common stock from initial public offering, net of issuance costs and underwriting fees (in shares)				11,721,456
Issuance of common stock from initial public offering, net of issuance costs and underwriting fees of $5.1 million	180,189,000			$ 1,000	180,188,000
Repurchase of unvested restricted common stock (in shares)				(11,160)
Stock-based compensation expense	6,459,000				6,459,000
Net loss	(121,821,000)						(121,821,000)
Change in unrealized loss on investments, net of tax	$ (357,000)					(357,000)
Ending balance (in shares) at Dec. 31, 2022	97,209,213			97,209,213
Ending balance at Dec. 31, 2022	$ 316,270,000			$ 2,000	$ 609,849,000	$ (384,000)	$ (293,197,000)

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE AND CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Series A Redeemable Convertible Preferred Stock
Issuance costs		$ 41	$ 46
Series B Convertible Preferred Stock
Issuance costs		$ 356
Common Stock
Issuance costs	$ 5,100

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	$ (121,821)	$ (165,367)	$ (3,410)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	2,224	568	43
Amortization of premiums and discount on short-term investments	(250)	715	0
Stock-based compensation expense	6,459	1,746	391
Non cash research and development expense for licenses	0	12,020	0
Non cash consideration received under related party collaboration arrangement	0	0	(5,360)
Non cash payment to Beam	0	0	150
Non cash lease expense	9,790	4,293	0
Loss on fixed asset disposal	8	0	0
Deferred income taxes	(964)	(624)	1,867
Change in fair value of preferred stock tranche right liability	0	74,319	10,904
Change in fair value of anti-dilution obligation	0	6,681	700
Change in fair value of related party short-term investment	8,128	391	(10,867)
Non cash other income (expense)	0	0	(126)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,738)	(885)	(388)
Accounts payable	2,458	1,185	250
Accrued expenses and other current liabilities	(25,873)	35,206	302
Lease liabilities	(10,248)	(4,330)	0
Net cash used in operating activities	(131,827)	(34,082)	(5,544)
Cash flows from investing activities:
Purchases of property and equipment	(16,095)	(4,150)	(639)
Purchase of short-term investments	(123,336)	(81,980)	0
Matured short-term investments	93,000	13,000	0
Payments of security deposits	(665)	(496)	(423)
Net cash used in investing activities	(47,096)	(73,626)	(1,062)
Cash flows from financing activities:
Payments of deferred offering costs	(4,042)	(1,086)	(20)
Proceeds from initial public offering, net of underwrites discounts and commissions and deferred offering costs	185,317	0	0
Net proceeds from stock option exercises	219	0	0
Net cash provided by financing activities	181,494	269,278	34,934
Net increase (decrease) in cash, cash equivalents and restricted cash	2,571	161,570	28,328
Cash and cash equivalents at beginning of period	198,545	36,975	8,647
Cash and cash equivalents at end of period	201,116	198,545	36,975
Supplemental cash flow information:
Right-of-use assets obtained in exchange for new operating lease liabilities	28,590	12,264	0
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock to common stock upon closing of initial public offering	395,800	0	0
Settlement of anti-dilution obligation	0	7,536	0
Settlement of related party forward contract	12,020	0	0
Cash taxes paid	141	0	0
Deferred offering costs included in accounts payable and accrued expenses at period end	0	410	0
Purchases of property and equipment included in accounts payable and accrued expenses at period end	969	754	0
Accretion of preferred stock to redemption value	0	1,468	1,645
Short-term investment in connection with related party collaboration arrangement	0	0	5,486
Unrealized loss on short-term investments	357	27	0
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	187,620	185,420	36,975
Restricted cash	13,496	13,125	0
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	201,116	198,545	36,975
Series A Redeemable Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from the issuance of convertible preferred stock	0	70,721	34,954
Cash received in advance from issuance of convertible preferred stock series A	0
Supplemental disclosure of non-cash investing and financing activities:
Settlement of Series A preferred stock tranche obligation	0	91,834	0
Issuance of Series A preferred stock at a price below fair value	0	998	0
Accretion of preferred stock to redemption value		1,468	1,645
Series B Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from the issuance of convertible preferred stock	$ 0	$ 199,643	$ 0

Nature of the Business and Basis of Presentation	12 Months Ended
Nature of the Business and Basis of Presentation	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	Nature of the Business and Basis of Presentation Prime Medicine, Inc., together with its consolidated subsidiary (the “Company”) is a biotechnology company committed to deliver genetic therapies to address diseases by deploying gene editing technology, Prime Editing. The company is deploying Prime Editing technology, a versatile, precise, efficient and broad gene editing technology, which is designed to make only the right edit at the right position within a gene. With the theoretical potential to repair approximately 90 percent of known disease-causing genetic mutations across many organs and cell types, medicines based on Prime Editing, if approved, could offer a one-time curative genetic therapeutic option to a broad set of patients. The Company was incorporated in the State of Delaware in September 2019. Its principal offices are in Cambridge, Massachusetts. Liquidity and capital resources Since its inception, the Company has devoted substantially all of our resources to building our Prime Editing platform and advancing development of our portfolio of programs, establishing and protecting our intellectual property, conducting research and development activities, organizing and staffing our company, business planning, raising capital and providing general and administrative support for these operations. 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. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. In October 2022, the Company completed its IPO of its common stock. In connection with its IPO, the Company issued and sold 11,721,456 shares of its common stock, including 1,427,338 shares pursuant to the exercise of the underwriters’ option to purchase additional shares, at a price to the public of $17.00 per share. As a result of the IPO, the Company received $180.2 million in net proceeds, after deducting underwriting discounts, commissions and offering costs of $19.1 million. In connection with the IPO, all outstanding shares of redeemable convertible preferred stock converted into 51,923,758 shares of the Company’s common stock. The Company is subject to risks and uncertainties common to early stage companies in the biotechnology industry, including, but not limited to, completing preclinical studies and clinical trials, obtaining regulatory approval for product candidates, market acceptance of products, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third-party organizations, protection of proprietary technology, compliance with government regulations, the impact of the COVID-19 pandemic, and the ability to raise additional capital to fund operations. The Company’s product candidates currently under development will require significant additional 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. Since its inception, the Company has incurred substantial losses and as of December 31, 2022, the Company had an accumulated deficit of $293.2 million. The Company expects to generate operating losses and negative operating cash flows for the foreseeable future. The Company expects that its cash, cash equivalents, short-term investments, and related party short-term investments as of December 31, 2022 of $293.9 million will be sufficient to fund its operations for at least the next twelve 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 would 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. Reverse Stock Split On October 12, 2022, in connection with the Company’s initial public offering (“IPO”), the Company effected a 1-3.10880 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios of each series of the Company’s preferred stock (see Note 6). Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this stock split and adjustment of the preferred stock conversion ratios. Basis of Presentation The accompanying consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary. Intercompany balances and transactions have been eliminated in consolidation. The accompanying consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“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 Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Impact of the COVID-19 Pandemic The Company is subject to a number of risks associated with the COVID-19 global pandemic, including potential delays associated with the Company’s ongoing preclinical studies and anticipated clinical trials. COVID-19 may have an adverse impact on the Company’s operations, supply chains and distribution systems or those of its third-party vendors and collaborators, and increase expenses, including as a result of impacts associated with preventive and precautionary measures that are being taken, such as restrictions on travel and border crossings, quarantine policies and social distancing. The Company and its third-party vendors and collaborators may experience disruptions in supply of items that are essential for its research and development activities. The Company cannot predict the scope and severity of any economic recovery after the COVID-19 pandemic abates, including following any additional “waves” or other intensifying of the pandemic will have on its financial condition, operations, and business plans.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Significant Accounting Policies

Summary of Significant Accounting Policies

Use of Estimates

The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected within these consolidated financial statements include, but are not limited to, revenue recognition, the valuation of the Company’s common stock and stock-based awards, the valuation of preferred stock tranche right liability, the valuation of the anti-dilution obligation and the valuation of the related party forward contract liability. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Actual results may differ materially from those estimates or assumptions.

Concentrations of Credit Risk

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents and short-term investments. The Company invests in U.S. Treasury securities and maintains its cash and cash equivalents at high-quality and accredited financial institutions in amounts that could exceed federally

insured limits. Cash equivalents are invested in money market funds. However, the Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original maturity of three months or less at the time of initial purchase to be cash equivalents. As of December 31, 2022 and 2021, the amount of cash equivalents included in cash and cash equivalents totaled $120.5 million and $49.5 million, respectively.

Restricted Cash

Restricted cash consisted of letters of credit totaling $13.5 million and $13.1 million as of December 31, 2022, and 2021, respectively, that are required to be maintained in connection with the Company’s lease arrangements. Both letters of credit are in the name of the Company’s landlords and are required to fulfill lease requirements in the event the Company should default on its lease obligations. As of both December 31, 2022 and 2021, the Company classified its restricted cash as non-current on the consolidated balance sheets based on the release dates of the restrictions.

Short-term Investments and Related Party Short-Term Investment

The Company’s short-term investments consist of investments in debt, including U.S. Treasury securities with remaining maturities beyond three months at the date of purchase and one year or less from the balance sheet date. As of both December 31, 2022 and 2021, all of the Company’s debt securities were classified as available-for-sale and were carried at fair market value (see Note 3). The unrealized losses on the Company’s available-for-sale debt securities are recorded in other comprehensive loss in the consolidated statements of operations and comprehensive loss.

Short-term debt securities are considered impaired when a decline in fair value is judged to be other-than-temporary. The Company consults with its investment managers and considers available quantitative and qualitative evidence in evaluating potential impairment of its short-term investments on a quarterly basis. If the cost of an individual investment exceeds its fair value, the Company evaluates, among other factors, general market conditions, the duration and extent to which the fair value is less than cost and its intent and ability to hold the investment. Once a decline in fair value is determined to be other-than-temporary, an impairment charge will be recorded to other income (expense), net, in the consolidated statements of operations and comprehensive loss.

The Company’s related party short-term equity investment was obtained from the collaboration agreement with Beam Therapeutics Inc. (“Beam”), which is a public company trading on the Nasdaq Exchange. At each reporting date, the Company will mark-to-market the Beam common stock to the fair value of the related party short-term investment.

The Company's equity securities with readily determinable fair values are recorded at fair value based upon the market prices of the securities at each reporting date. Unrealized and realized gains and losses on the Company’s equity investment is included as a component of other income (expense) in the consolidated statements of operations and comprehensive loss. The costs of debt and equity securities for purposes of computing realized and unrealized gains and losses is based on the specific identification method.

Deferred Offering Costs

The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded as a reduction of the proceeds from the offering, either as a reduction of the carrying value of the preferred stock or in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss. As of December 31, 2022, there were no deferred offering costs capitalized. As of December 31, 2021, there were $1.5 million of deferred offering costs capitalized.

Fair Value Measurements

Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

Level 1 — Quoted prices in active markets for identical assets or liabilities.

Level 2 — Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

Level 3 — Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The Company’s cash equivalents, short-term investments, preferred stock tranche right liability, anti-dilution obligation and related party forward contract liability are carried at fair value, determined according to the fair value hierarchy described above (see Note 3). The carrying values of the Company’s accounts payable and accrued expenses approximate their fair values due to the short-term nature of these liabilities.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset as follows:


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of remaining lease term or useful life

Costs for capital assets not yet placed into service are capitalized and are depreciated once placed into service. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance that do not improve or extend the life of the respective assets are charged to expense as incurred.

Impairment of Long-Lived Assets

Long-lived assets consist primarily of property and equipment, and operating lease right-of-use assets. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. If such asset group is considered to be impaired, the impairment loss to be recognized is measured based on the excess of the carrying value of the impaired asset group over its fair value.

For both the years ended December 31, 2022 and 2021, the Company did not recognize any impairment losses on long-lived assets.

Leases

Prior to January 1, 2021, the Company accounted for leases in accordance with Accounting Standards Codification (“ASC”) ASC 840, Leases. At lease inception, the Company determined if an arrangement was an operating or capital lease. For operating leases, the Company recognized rent expense, inclusive of rent escalation, on a straight-line basis over the lease term.

Effective on January 1, 2021, the Company accounts for leases in accordance with ASC 842, Leases. In accordance with ASC 842, Leases, the Company determines if an arrangement is or contains a lease at inception. A contract is or contains a lease if the contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. The Company classifies leases at the lease commencement date as operating or finance leases and records a right-of-use asset and a lease liability on the consolidated balance sheet for all leases with an initial lease term of greater than 12 months. Leases with an initial term of 12 months or less are not recorded in the balance sheet, but payments are recognized as expense on a straight-line basis over the lease term. The Company has elected not to recognize leases with terms of 12 months or less.

A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term. All other leases are recorded as operating leases.

The Company enters into contracts that contain both lease and non-lease components. Non-lease components may include maintenance, utilities, and other operating costs. The Company combines the lease and non-lease components of fixed costs in its lease arrangements as a single lease component. Variable costs, such as utilities or maintenance costs, are not included in the measurement of right-of-use assets and lease liabilities, but rather are expensed when the event determining the amount of variable consideration to be paid occurs.

Finance and operating lease assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term using the discount rate implicit in the lease. If the rate implicit is not readily determinable, the Company utilizes an estimate of its incremental borrowing rate based upon the available information at the lease commencement date. Operating lease assets are further adjusted for prepaid or accrued lease payments. Operating lease payments are expensed using the straight-line method as an operating expense over the lease term. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Finance lease assets are amortized to depreciation expense using the straight-line method over the shorter of the useful life of the related asset or the lease term. Finance lease payments are bifurcated into (i) a portion that is recorded as imputed interest expense and (ii) a portion that reduces the finance liability associated with the lease.

Certain of the Company’s leases include options to extend or terminate the lease. The amounts determined for the Company’s right-of-use assets and lease liabilities generally do not assume that renewal options or early-termination provisions, if any, are exercised, unless it is reasonably certain that the Company will exercise such options.

In addition, the Company examines other contracts with suppliers, vendors and outside parties to identify whether such contracts contain an embedded lease and, as applicable, records such embedded leases in accordance with ASC 842.

Segment Information

The Company operates and manages its business as a single segment for the purposes of assessing performance and making operating decisions. The Company’s chief executive officer, who is the chief operating decision maker, reviews the Company’s financial information on a consolidated basis for purposes of evaluating financial performance and allocating resources. All of the Company’s long-lived assets are located in the United States and all of the Company’s revenue was derived in the United States.

Classification and Accretion of Redeemable Convertible Preferred Stock

The Company has classified the convertible preferred stock outside of stockholders’ equity (deficit) on the Company’s consolidated balance sheets because the holders of such stock have redemption features and certain liquidation rights in the event of a deemed liquidation that, in certain situations, are not solely within the control of the Company and would require the redemption of the then-outstanding convertible preferred stock.

The Company's Series A redeemable convertible preferred stock (“Series A Preferred Stock”) was redeemable in an amount equal to the original issue price per share plus all declared but unpaid dividends thereon. The Company recorded periodic accretion to the values of its outstanding Series A Preferred Stock such that the carrying value of the Series A Preferred Stock would be equal to the redemption value at the earliest redemption date. Adjustments to the carrying value of the Series A Preferred Stock at each reporting date resulted in an increase to net loss attributable to common stockholders. In April 2021, the redemption rights for Series A Preferred Stock were removed and such shares of preferred stock were no longer redeemable. After the removal of the redemption rights, the Company did not record any further accretion to the carrying value of Series A Preferred Stock (see Note 6). In connection with the IPO, all outstanding shares of Series A convertible preferred stock converted into 37,236,772 shares of the Company’s common stock.

The Company’s Series B convertible preferred stock is not redeemable, except in the event of a deemed liquidation (see Note 6). Because the occurrence of a deemed liquidation event is not currently probable, the carrying values of the Series B convertible preferred stock are not being accreted to their redemption values. Subsequent adjustments to the carrying values of the convertible preferred stock would be made only when a deemed liquidation event becomes probable. In connection with the IPO, all outstanding shares of Series B redeemable convertible preferred stock converted into 14,686,986 shares of the Company’s common stock.

Revenue Recognition

The Company recognizes revenue in accordance with ASU 2014-09, Revenue from Contracts with Customers (Topic 606) and its related amendments, or, collectively, ASC 606.

Under ASC 606, revenue is recognized when a 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. In order to achieve this core principle, the Company applies the following five steps when recording revenue: (1) identify the contract, or contracts, with the customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract and (5) recognize revenue when, or as, performance obligations are satisfied.

At contract inception, the Company assesses the goods or services promised within each contract, whether each promised good or service is distinct, and determines those that are performance obligations. 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 their own and whether the required expertise is readily available. In addition, the Company considers whether the collaboration partner can benefit from a promise for its intended purpose without the receipt of the remaining promises, whether the value of the promise is dependent on the unsatisfied promises, whether there are other vendors that could provide the remaining promises, and whether it is separately identifiable from the remaining promises. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when or as the performance obligation is satisfied.

In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its arrangements, the Company performs the following 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 assessment of 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. As part of the accounting for arrangements under ASC 606, the Company must use significant judgment to determine: a) the performance obligations based on the determination under step (ii) above; b) the transaction price under step (iii) above; and c) the standalone selling price for each performance obligation identified in the contract for the allocation

of transaction price in step (iv) above. The Company also uses judgment to determine whether milestones or other variable consideration, except for royalties and sales-based milestones where such payments principally relate to a license of intellectual property, should be included in the transaction price as described below. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price 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 in the period of adjustment. The transaction price is allocated to each performance obligation based on the relative standalone selling price of each performance obligation in the contract, and the Company recognizes revenue based on those amounts when, or as, the performance obligations under the contract are satisfied. The Company utilizes key assumptions to determine the standalone selling price, which may include other comparable transactions, pricing considered in negotiating the transaction, probabilities of technical and regulatory success and the estimated costs. Certain 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 to each performance obligation are consistent with the amounts the Company would expect to receive for each performance obligation.

Research and Development Expenses

Research and development expenses are expensed as incurred. Research and development expenses may consist of costs incurred in connection with acquired in-process research and development and performing research and development activities, including amounts incurred under agreements with external vendors and consultants engaged to perform preclinical studies and to manufacture research and development materials for use in such studies, salaries and related personnel costs, stock-based compensation, consultant fees, and third-party license fees.

Upfront payments under license agreements are expensed upon receipt of the license, and annual maintenance fees under license agreements are expensed over the maintenance period. Milestone payments under license agreements are accrued, with a corresponding expense being recognized, in the period in which the milestone is determined to be probable of achievement and the related amount is reasonably estimable.

Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed.

Acquired In-Process Research and Development

The Company measures and recognizes asset acquisitions or licenses to intellectual property that are not deemed to be business combinations based on the cost to acquire or license the asset or group of assets, which includes transaction costs. Goodwill is not recognized in asset acquisitions or transaction to license intellectual property. In an asset acquisition or license to intellectual property, the cost allocated to acquire in-process research and development (“IPR&D”) with no alternative future use is recognized as research and development expense on the acquisition date.

Upfront and milestone payments made are accrued for and expensed when the achievement of the milestone is probable up to the point of regulatory approval. Milestone payments made upon regulatory approval are capitalized and amortized over the remaining useful life of the related product.

Acquired IPR&D for the year ended December 31, 2022 consisted of the upfront cash consideration for a license arrangement of $0.2 million for the 2022 Broad License Agreement (see Note 11). Acquired IPR&D for the year ended December 31, 2021, consisted of (i) the related party forward contract liability for the issuance of 1,101,525 shares of common stock initially valued at $12.0 million and (ii) upfront cash consideration for a license arrangement of $30.0 million (see Note 11). In January 2022, the Company made the upfront payment of $30.0 million and issued 1,101,525 shares of its common stock, with a fair value of $12.0 million, to Myeloid pursuant to the terms of the Myeloid Collaboration Agreement (see Note 11 and 14). There was no acquired IPR&D recognized for the year ended December 31, 2020.

Patent Costs

The Company expenses as incurred all patent-related costs incurred in connection with filing and prosecuting patent applications due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses in the statements of operations and comprehensive loss.

Contingencies

The Company is subject to contingent liabilities, such as legal proceedings and claims, that arise in the ordinary course of business activities. The Company accrues for loss contingencies when losses become probable and are reasonably estimable. If the reasonable estimate of the loss is a range and no amount within the range is a better estimate, the minimum amount of the range is recorded as a liability on the consolidated balance sheets. The Company does not accrue for contingent losses that, in its judgment, are considered to be reasonably possible, but not probable; however, it discloses the range of reasonably possible losses. As of December 31, 2022 and 2021, no liabilities were recorded for loss contingencies (see Note 12).

Stock-Based Compensation

The Company measures all stock-based awards granted to employees, directors and non-employees based on the fair value of the awards on the date of grant using the Black-Scholes option-pricing model. The Company measures restricted common stock awards using the difference, if any, between the purchase price per share of the award and the fair value of the Company’s common stock at the date of grant.

The Company grants stock options and restricted stock awards that are subject to either service or performance-based vesting conditions. Compensation expense for awards to employees and directors with service-based vesting conditions is recognized using the straight-line method over the requisite service period, which is generally the vesting period of the respective award. Compensation expense for awards to non-employees with service-based vesting conditions is recognized in the same manner as if the Company had paid cash in exchange for the goods or services, which is generally over the vesting period of the award. Forfeitures are accounted for as they occur. Compensation expense for awards to employees and non-employees with performance-based vesting conditions is recognized based on the grant-date fair value over the requisite service period using the accelerated attribution method to the extent achievement of the performance condition is probable. As of each reporting date, the Company estimates the probability that specified performance criteria will be met and does not recognize compensation expense until it is probable that the performance-based vesting condition will be achieved.

The Company classifies stock-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified.

Preferred Stock Tranche Right Liability

Each preferred stock tranche right liability was recorded at fair value upon the date of issuance of each preferred stock tranche right and was subsequently remeasured to fair value at each reporting date. Changes in the fair value of the preferred stock tranche right liability are recognized as a component of other income (expense), net in the consolidated statement of operations and comprehensive loss. Changes in the fair value of the preferred stock tranche right liability were recognized until the preferred stock tranche right was settled in full upon the satisfaction of certain conditions in April 2021.

Comprehensive Loss

Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the year ended December 31, 2020 there was no difference between net loss and comprehensive loss. For the years ended December 31, 2022 and 2021, comprehensive loss includes net loss and unrealized gains (losses) on investments.

Net Loss per Share Attributable to Common Stockholders

The Company applies the two-class method when computing net income (loss) per share attributable to common stockholders as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (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 (loss) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to share in the undistributed earnings as if all income (loss) for the period had been distributed. The Company considers its convertible preferred stock to be participating securities as, in the event a dividend is paid on common stock, the holders of convertible preferred stock would be entitled to receive dividends on a basis consistent with the common stockholders. There is no allocation required under the two-class method during periods of loss since the participating securities do not have a contractual obligation to share in the losses of the Company.

Basic net income (loss) per share attributable to common stockholders is computed by dividing the net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding for the period, excluding potentially dilutive common shares and of unvested restricted common stock. Diluted net income (loss) per share 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 income (loss) per share attributable to common stockholders is computed by dividing the diluted net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding for the period, including potential dilutive common shares. For purposes of this calculation, the Company’s outstanding stock options and convertible preferred stock are considered potential dilutive common shares.

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

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined based on the differences between the financial statement basis and tax basis of assets and liabilities using enacted tax rates in effect for the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50 percent likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. The Company had accrued no amounts for interest or penalties related to uncertain tax positions as of December 31, 2022, 2021, and 2020.

Recently Adopted Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), as subsequently amended, which sets out the principles for the recognition, measurement, presentation, and disclosure of leases for both parties to a contract (i.e., lessees and lessors), and replaces the existing guidance in ASC 840, Leases.

The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine the recognition pattern of lease expense over the term of the lease. In addition, a lessee is required to record (i) a right-of-use asset and a lease liability on its balance sheet for all leases with accounting lease terms of more than 12 months regardless of whether it is an operating or financing lease and (ii) lease expense in its consolidated statement of operations and comprehensive loss for operating leases and amortization and interest expense in its consolidated statement of operations and comprehensive loss for financing leases. Leases with a term of 12 months or less may be accounted for similar to existing guidance for operating leases under ASC 840. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842), which added an optional transition method that allows companies to adopt the standard as of the beginning of the year of adoption as opposed to the earliest comparative period presented. This guidance is effective for the Company for annual periods beginning after December 15, 2021, including interim periods within that fiscal year. Early adoption is permitted.

The Company adopted the new leasing standard effective January 1, 2021, using the modified retrospective transition 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. The Company has elected to apply the package of practical expedients requiring no reassessment of whether any expired or existing contracts are or contain leases, the lease classification of any expired or existing leases, or the capitalization of initial direct costs for any existing leases.

Upon its adoption of ASC 842, the Company recorded lease liabilities and their corresponding right-of-use assets based on the present value of lease payments over the remaining lease term. The adoption of ASC 842 resulted in the recognition of operating lease liabilities of $2.7 million and right-of-use assets of $2.8 million and the derecognition of prepaid rent balances recorded in other assets of $0.1 million on the Company’s balance sheet as of January 1, 2021. The adoption impact relates to the Company’s existing operating lease for office and laboratory space. The adoption of ASU 2016-02 did not have a material impact on the Company’s statements of operations and comprehensive loss or statements of cash flows.

In August 2020, the FASB issued ASU 2020-06, Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40). This standard eliminates the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, the new guidance modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted earnings per share (“EPS”) computation. Additionally, the amended guidance requires the application of the if-converted method for calculating diluted EPS and the treasury stock method will no longer be available. For public business entities, it is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years using the fully retrospective or modified retrospective method. For all other entities, the amendments are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company adopted ASU 2020-06 on January 1, 2022. The adoption of ASU 2020-06 did not have a material impact on the Company’s consolidated financial statements.

Recently Issued Accounting Pronouncements Not Yet Adopted

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company will adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and will do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. As a result of this election, the Company’s financial statements may not be comparable to those public companies that comply with new or revised accounting pronouncements as of public company effective dates. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for nonpublic companies.

Fair Value Measurements

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following tables present the Company’s fair value hierarchy for its assets and liabilities that are measured at fair value on a recurring basis and indicate the level within the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value (in thousands):


	Fair Value Measurements at December 31, 2022
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	—	$	120,511	$	—	$	120,511
Short-term investment:
U.S. Treasury Bonds	—		98,467		—		98,467
Related party short-term investment:
Beam equity securities	7,834		—		—		7,834
	$	7,834	$	218,978	$	—	$	226,812


	Fair Value Measurements at December 31, 2021
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	—	$	49,450	$	—	$	49,450
Short-term investment:
U.S. Treasury bills and government securities	—		68,238		—		68,238
Related party short-term investment:
Beam equity securities	15,962		—		—		15,962
	$	15,962	$	117,688	$	—	$	133,650
Liabilities:
Related party forward contract liability	—		—		12,020		12,020
	$	—	$	—	$	12,020	$	12,020

Money market funds were valued by the Company based on observable inputs, which represent a Level 2 measurement within the fair value hierarchy. For the years ended December 31, 2022 and 2021, there were no transfers between Level 1, Level 2 and Level 3.

The Company classifies its U.S. Treasury securities as short-term based on each instrument’s underlying contractual maturity date. The fair value of the Company’s U.S. Treasury securities and money market funds are classified as Level 2 because they are valued using observable inputs to quoted market prices, benchmark yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency and U.S. Treasury securities.

The underlying securities held in the money market funds held by the Company are all government backed securities.

Short-term investments consisted of the following (in thousands):


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments:
U.S. Treasury Bonds	$	98,851	$	—	$	(384)	$	98,467
Related party short-term investment:
Beam equity securities	5,486		2,348		—		7,834
	$	104,337	$	2,348	$	(384)	$	106,301


	December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments:
U.S. Treasury bills and government securities	$	68,265	$	—	$	(27)	$	68,238
Related party short-term investment:
Beam equity securities	$	5,486	$	10,476	$	—	$	15,962
	$	73,751	$	10,476	$	(27)	$	84,200

The contractual maturities of the Company’s short-term investments in available-for-sale debt securities held were as follows (in thousands):


	December 31, 2022		December 31, 2021
Due within one year	$	98,467	$	68,238
	$	98,467	$	68,238

Valuation of the Related Party Forward Contract Liability

The Company measured its related party forward contract liability, which was established in connection with its obligation to issue shares of its common stock to Myeloid Therapeutics, Inc. (“Myeloid”) under a stock subscription agreement (see Note 11), at fair value based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The initial fair value of the related party forward contract liability was determined based on the number of shares to be issued by the Company and the then per share fair value of the Company’s common stock, which was determined based, in part, on a third-party valuation that utilized methodologies and assumptions consistent with the Company’s most recent common stock valuations, including on a minority, nonmarketable interest basis.

Changes in the fair value of the related party forward contract liability will be recognized as other income (expense), net in the consolidated statements of operations through the settlement date. There was no change in the fair value of the Company’s common stock from the initial date of the related party forward contract liability and December 31, 2021 and the settlement which occurred in January 2022. Upon settlement, the fair value of the related party forward contract liability was reclassified to equity upon issuance of the common stock to Myeloid.

A reconciliation of the related party forward contract liability measured and recorded at fair value on a recurring basis is as follows (in thousands):


	Forward Contract
Balance at December 31, 2020	$	—
Initial fair value of related party forward contract liability	$	12,020
Balance at December 31, 2021	$	12,020
Reclassification of related party forward contract liability upon settlement	$	(12,020)
Balance at December 31, 2022	$	—

Valuation of Preferred Stock Tranche Right Liability

The preferred stock tranche right liability was composed of the fair value of rights to purchase Series A Preferred Stock (see Note 6). The fair value of the preferred stock tranche right liability was determined based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The fair value of the preferred stock tranche right liability, which considered as inputs the estimated fair value of the preferred stock as of each valuation date, the risk-free interest rate, volatility and estimated time to each tranche closing.

The most significant assumption in the Black-Scholes option pricing model impacting the fair value of the preferred stock tranche right liability is the fair value of the Company’s convertible preferred stock as of each measurement date. The Company determines the fair value per share of the underlying convertible preferred stock by taking into consideration the most recent sales of its convertible preferred stock, results obtained from third-party valuations and additional factors the Company deems relevant. In November 2020, the second tranche of the Series A Preferred Stock closed. The fair value of each Series A Preferred Stock was $0.73 per share upon the closing of the second tranche. As of December 31, 2020, the fair value of Series A Preferred Stock was $0.76 per share. In April 2021, the third and fourth tranches of the Series A Preferred Stock closed. Upon satisfaction of certain conditions and the closing date of the third and fourth tranches, the associated Series A preferred stock tranche right liability was settled. The fair value of Series A Preferred Stock was $2.31 per share upon the closing of the third and fourth tranches. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve for time periods approximately equal to the remaining estimated time to each tranche closing. The volatility is based on the historical volatility of publicly traded peer companies. Changes in the estimated fair value of the Company’s convertible preferred stock can have a significant impact on the fair value of the preferred stock tranche right liability.

In April 2021, the third and fourth tranches of the Series A Preferred Stock closed and the preferred stock tranche right liability was settled. During the year ended December 31, 2021, we recognized $74.3 million as a component of other income (expense), net related to the change in fair value of the preferred stock tranche right liability. During the year ended December 31, 2020, we recognized $10.9 million as a component of other income (expense), net related to the change in fair value of the preferred stock tranche right liability.

Valuation of Anti-dilution Obligation

The fair value of the anti-dilution obligation recognized in connection with the anti-dilution provisions set forth in the Company's license agreement with Broad Institute (see Note 11) was determined based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The fair value of the anti-dilution obligation was estimated using a probability-weighted scenario which considered as inputs the probability of occurrence of events that would trigger the issuance of shares, including (i) the closing of Series A Preferred Stock, (ii) the Company’s initial public offering, and (iii) no future sale of equity securities.

The weighted-average fair value of all scenarios was calculated utilizing the fair value per share of the underlying common stock. Changes in the estimated fair value of common stock and the probability of achieving different financing scenarios can have a significant impact on the fair value of the anti-dilution obligation. The most significant assumption impacting the fair value of the anti-dilution obligation was the fair value of the Company’s common stock as of each measurement date. The Company determined the fair value per share of the underlying common stock by taking into consideration the most recent sales of its convertible preferred stock, results obtained from third-party valuations and additional factors the Company deems relevant. The per share fair value of the

Company’s common stock was $0.35 as of December 31, 2020. Immediately prior to the settlement of the anti-dilution obligation, the fair value of the Company’s common stock was $3.02 per share.

The anti-dilution obligation was initially recorded at fair value upon entering into the license agreement with Broad Institute and was subsequently remeasured to fair value at each reporting date. Changes in fair value of the anti-dilution obligation were recognized as a component of other income (expense), net in the consolidated statements of operations and comprehensive loss. Changes in the fair value of the anti-dilution obligation were recognized until achievement of $100.0 million in cumulative equity financing is raised by the Company, which was achieved in connection with the fourth Series A Preferred Stock closing in April 2021, resulting in the issuance of 2,498,850 shares of common stock to Broad Institute with a fair value of $7.5 million. During the year ended December 31, 2021, we recognized $6.7 million as a component of other income (expense), net related to the change in fair value of the anti-dilution obligation. During the year ended December 31, 2020, we recognized $0.7 million as a component of other income (expense), net related to the change in fair value of the anti-dilution obligation.

Property, Plant and Equipment [Abstract]

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

Property and Equipment, Net

12 Months Ended

Dec. 31, 2022

Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2022		2021
Laboratory equipment	$	19,422	$	5,274
Leasehold improvement	564		125
Furniture and fixture	235		144
Computer Hardware and Software	11		—
Construction in progress	1,608		—
	21,840		5,543
Less: Accumulated depreciation and amortization	(2,831)		(611)
	$	19,009	$	4,932

Depreciation and amortization expense of property and equipment for the years ended December 31, 2022, 2021, and 2020 was $2.2 million, $0.6 million, and $43.0 thousand, respectively.

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	December 31,
	2022		2021
Accrued Myeloid license fee–related party	$	—	$	30,000
Accrued employee compensation and benefits	6,529		2,364
Accrued professional fees	2,162		3,830
Lab-related supplies and services	1,548		719
Other	449		279
	$	10,688	$	37,192

Convertible Preferred Stock

12 Months Ended

Dec. 31, 2022

Temporary Equity Disclosure [Abstract]

Convertible Preferred Stock

The Company has issued Series A Preferred Stock and Series B convertible preferred stock (the “Series B Preferred Stock” and, together with the Series A Preferred Stock, the “Preferred Stock”).

The Series A preferred stock and Series B preferred stock, described in more detail below, converted into 37,236,772 shares and 14,686,986 shares of common stock, respectively, in October 2022 as part of the Company’s IPO.

In September 2019, the Company completed its first closing of its Series A Preferred Stock and issued and sold 10,000,001 shares of Series A Preferred Stock at a price of $1.00 per share for gross proceeds of $10.0 million (the “2019 Preferred Stock Financing”). The Company incurred issuance costs of $20,000 in connection with this transaction.

The purchase agreement for the Series A Preferred Stock obligated the investors of the 2019 Preferred Stock Financing to purchase an additional 104,999,997 Series A Preferred Stock at a price of $1.00 per share in the subsequent closings upon certain conditions (“Series A Subsequent Closings”). The investors’ obligation to purchase shares in the subsequent closing terminates upon occurrence of a Deemed Liquidation Event, the Company’s initial public offering, or bankruptcy by the Company. If an investor did not participate in the subsequent closing when obligated to do so, then any existing Series A Preferred Stock held by that investor would be converted into common shares of the Company on a ten-for-one basis.

The Company concluded that these obligations of investors to participate in the subsequent closing of Series A Preferred Stock met the definition of a freestanding financial instrument that was required to be recorded as a liability at fair value as (i) the instruments are legally detachable and separately exercisable from the Series A Preferred Stock and (ii) the rights will require the Company to transfer assets upon future closings of the Series A Preferred Stock. Upon the first closing of the Series A Preferred Stock in September 2019, the Company recorded a preferred stock tranche right liability of $6.3 million and a corresponding reduction to the carrying value of the Series A Preferred Stock (see Note 3).

In November 2020, the Company completed the second closing of its Series A Preferred Stock, in which the Company issued and sold 34,999,999 shares of Series A Preferred Stock, at a price of $1.00 per share, for gross proceeds of $35.0 million and incurred $46,000 of issuance costs. As the fair value of the Series A Preferred Stock was $0.73 at the time of the second closing, the Company recorded a capital contribution of $9.5 million for the difference between the fair value per share and the $1.00 per share paid by the holders of the Series A Preferred Stock participating in the second closing, which included members of the Company’s board of directors.

In April 2021, the Company completed the third and fourth closings of its Series A Preferred Stock, in which the Company issued and sold an aggregate of 70,761,842 shares of Series A Preferred Stock, at a price of $1.00 per share, for gross proceeds of $70.8 million and incurred $41,000 of issuance costs. As a result of this issuance, the Series A preferred stock tranche right liability with a then fair value of $91.8 million, based on a fair value of $2.31 per share of Series A Preferred Stock immediately prior to the closings, was settled in full and reclassified as an increase to the carrying value of Series A Preferred Stock.

In April 2021, the Company issued and sold 45,658,957 shares of Series B Preferred Stock, at a price of $4.3803 per share, for gross proceeds of $200.0 million and incurred $0.4 million of issuance costs.

Upon issuance of each series of Preferred Stock, the Company assessed the embedded conversion and liquidation features of the securities and determined that such features did not require the Company to separately account for these features. The Company also concluded that no beneficial conversion feature existed on the issuance date of each series of Preferred Stock.

On October 12, 2022, in connection with the Company’s IPO, the Company effected a 1-for-3.10880 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios of each series of the Company’s preferred stock. Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this stock split and adjustment of the preferred stock conversion ratios.

As of December 31, 2021, the Preferred Stock consisted of the following (in thousands, except share amounts):


	December 31, 2021
	Preferred Stock Authorized	Preferred Stock Issued and Outstanding	Carrying Value		Liquidation Preference		Conversion price per share		Common Stock Issuable Upon Conversion
Series A Preferred Stock	115,761,842	115,761,842	$	196,157	$	125,000	$	3.1088	37,236,776
Series B Preferred Stock	45,658,957	45,658,957	$	199,643	$	210,814	$	13.6175	14,686,988
	161,420,799	161,420,799	$	395,800	$	335,814			51,923,764

During the year ended December 31, 2022, until the conversion of the all preferred stock upon the Company’s IPO, and as of December 31, 2021 and 2020, the Conversion Price was $3.1088 per share for Series A Preferred Stock and $13.6175 per share for Series B Preferred Stock, each subject to appropriate adjustment in the event of any share dividend, share split, combination or other similar recapitalization with respect to the Preferred Stock.

Through December 31, 2022, 2021, and 2020 no cash dividends have been declared or paid.

Redemption

As of December 31, 2020, at the written election of at least 65 percent of the holders of the outstanding shares of Series A Preferred Stock, voting together as a single class and on an as-converted to common stock basis, the shares of Series A Preferred Stock outstanding were redeemable, at any time on or after the fifth anniversary of issuance, in three equal annual installments commencing 60 days after receipt of the required vote. Shares of Series A Preferred Stock were redeemable in an amount equal to the Original Issue Price per share plus any accruing dividends accrued but unpaid thereon, whether or not declared.

In April 2021, in connection with the Series B Preferred Stock closing, the Company adopted an amended and restated certificate of incorporation, which removed the redemptions rights of the holders of Series A Preferred Stock. As a result of this amendment, Series A Preferred Stock was no longer redeemable at the option of the holders. The Company determined that the changes to the rights underlying the Series A Preferred Stock was not substantive and did not materially modify the rights and preferences of the holders of Series A Preferred Stock.

Prior to the amendment, the Company recognized changes in the redemption values of its Series A Preferred Stock over the period from the date of issuance to the earliest redemption date and adjusted the carrying value of the instrument to equal the redemption value at the redemption date. During years ended December 31, 2022, 2021, and 2020, the Company recorded adjustments to increase the carrying values of the Series A Preferred Stock by an aggregate of zero, $1.5 million, and $1.6 million, respectively, which resulted in an increase in redeemable convertible preferred stock by those amounts, offset by charges against additional paid-in-capital, if any, and then in the absence of additional paid-in capital the accretion is charged to the accumulated deficit.

Common Stock

Each share of common stock entitles the holder to one vote on all matters submitted to the stockholders for a vote. The holders of common stock are entitled to receive dividends, if any, as declared by the Company’s board of directors.

As of December 31, 2022, the Company had reserved 7,622,758 shares of common stock for the exercise of outstanding stock options for common stock, and the issuance of common stock options and restricted stock awards remaining available for grant under the 2022 Equity Incentive Plan. As of December 31, 2021, the Company had reserved 58,433,916 shares, of common stock for the conversion of shares of Preferred Stock into common stock, the exercise of outstanding stock options for common stock, and the issuance of common stock options and restricted stock awards remaining available for grant under the 2019 Equity Incentive Plan.

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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+ Details

Common Stock

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Common Stock

Convertible Preferred Stock

As of December 31, 2021, the Preferred Stock consisted of the following (in thousands, except share amounts):


	December 31, 2021
	Preferred Stock Authorized	Preferred Stock Issued and Outstanding	Carrying Value		Liquidation Preference		Conversion price per share		Common Stock Issuable Upon Conversion
Series A Preferred Stock	115,761,842	115,761,842	$	196,157	$	125,000	$	3.1088	37,236,776
Series B Preferred Stock	45,658,957	45,658,957	$	199,643	$	210,814	$	13.6175	14,686,988
	161,420,799	161,420,799	$	395,800	$	335,814			51,923,764

Through December 31, 2022, 2021, and 2020 no cash dividends have been declared or paid.

Redemption

Common Stock

Share-Based Payment Arrangement [Abstract]

+ References

+ Details

Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Stock-Based Compensation

2019 Equity Incentive Plan

The Company’s 2019 Stock Option and Grant Plan (the “2019 Plan”) provides for the Company to grant incentive stock options (“ISO”), non-qualified stock options, unrestricted stock awards, restricted stock awards (“RSA”) and other stock-based awards (collectively, the “Awards”) to the officers, employees, consultants and other key persons of the Company. The 2019 Plan is administered by the board of directors, or at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or its committee if so delegated.

The total number of shares of common stock issuable under the 2019 Plan was 6,171,635. In April 2021, the Company’s board of directors further increased the number of shares of common stock reserved for issuance under the plan from 6,171,635 shares to 11,561,815 shares. As of December 31, 2022 and 2021, there were no shares, and 2,405,824 shares, respectively, remaining available for future grants under the 2019 Plan. Shares of unused common stock underlying any Awards that are forfeited, canceled or reacquired by the Company prior to vesting will again be available for the grant of awards under the 2019 Plan.

The exercise price for stock options granted may not be less than the fair market value of the Company’s common stock on the date of grant, as determined by the board of directors, or at least 110 percent of the fair market value of the Company’s common stock on the date of grant in the case of an ISO granted to an employee who owns stock representing more than 10 percent of the voting power of all classes of stock (“10% Owner”) as determined by the board of directors as of the date of grant. The Company’s board of directors determines the fair market value of the Company’s common stock, taking into consideration its most recently available valuation of common stock performed by third parties as well as additional factors which may have changed since the date of the most recent contemporaneous valuation through the date of grant. Unless otherwise provided, at the time of grant, the options granted pursuant to the 2019 Plan expire ten years from the date of grant, or five years from the date of grant in the case of an ISO that is granted to a 10% Owner. Awards typically vest over four years, with the first 25 percent vesting on the first anniversary of the vesting commencement date and the remainder vesting in 36 equal monthly installments thereafter, contingent on the recipient’s continued employment, service or relationship with the Company.

In October 2022, the Company completed its IPO, and in connection with the closing the Board determined that no further awards would be granted under the 2019 Plan.

2022 Stock Option and Incentive Plan

On February 9, 2022, the Company’s board of directors adopted, and on October 10, 2022 its stockholders approved, the 2022 Stock Option and Incentive Plan (the “2022 Plan”), which became effective immediately preceding the date on which the registration statement for the Company’s IPO was declared effective by the SEC. The 2022 Plan allows the Company to make equity-based and cash-based incentive awards to its officers, employees, directors, and consultants. The 2022 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted common stock awards, restricted stock units and other stock-based awards. The number of shares initially reserved for issuance under the 2022 Plan is 8,041,688 shares, which includes the number of shares remaining available for grant under the 2019 Plan, as of the effective date, for the issuance of awards under the 2022 Plan. In addition, the number of shares reserved and available for issuance under the 2022 Plan will automatically increase on January 1, 2023 and each January 1 thereafter, by five percent of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the compensation committee.

The shares of common stock underlying any awards under the 2022 Plan and the 2019 Plan that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire, or are otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2022 Plan.

As of December 31, 2022, options to purchase 435,334 shares of common stock were issued and outstanding under the 2022 Plan.

2022 Employee Stock Purchase Plan

On February 9, 2022, the Company’s board of directors adopted, and on October 10, 2022 its stockholders approved, the 2022 Employee Stock Purchase Plan (the “2022 ESPP”), which became effective immediately preceding the date on which the registration statement for the Company’s IPO was declared effective by the SEC. A total of 971,350 shares of common stock were initially reserved for issuance under this plan. The number of shares of common stock that may be issued under the 2022 ESPP shall cumulatively increase beginning on January 1, 2023 and each January 1 thereafter through January 1, 2032, by the least of (i) 971,350 shares of common stock, (ii) one percent of the outstanding number of shares of common stock on the immediately preceding December 31, or (iii) such number of shares of common stock as determined by the administrator of the 2022 ESPP.

No shares of the Company’s common stock were issued and no stock-based compensation expense was recognized during the year ended December 31, 2022 related to the 2022 ESPP.

Stock Option Valuation

The fair value of each stock option grant is estimated on the grant date using the Black-Scholes option-pricing model. The Company historically had been a private company and lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. For options with service-based vesting conditions, the expected term of the Company’s options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is based on the fact that the Company has never paid cash dividends on common stock and does not expect to pay any cash dividends in the foreseeable future.

No stock options were granted during the year ended December 31, 2020.

The following table presents, on a weighted-average basis, the assumptions used in the Black-Scholes option-pricing model to determine the fair value of stock options granted:


	December 31, 2022			December 31, 2021
Fair value per share of underlying common stock	$	7.34		$	7.54
Risk-free interest rate	3.0		%	1.2		%
Expected term (in years)	6.0			6.0
Expected volatility	74.77		%	75.27		%
Expected dividend yield	—		%	—		%

Time-Based Stock Options

The following table summarizes the Company’s time-based stock option activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
				(in years)




Outstanding at December 31, 2021	2,761,555	$	3.98	9.72	$	19,154
Granted	1,424,926	$	10.90
Exercised	(59,774)	$	3.67
Forfeited	(172,442)	$	5.05
Outstanding at December 31, 2022	3,954,265	$	6.43	9.02	$	48,030
Vested and exercisable at December 31, 2022	875,727	$	4.04	8.72	$	12,736
Vested and expected to vest at December 31, 2022	3,954,265	$	6.43	9.02	$	48,030

The weighted-average grant-date fair value of stock options granted was $7.40 and $1.89 per share for the years ended December 31, 2022 and 2021, respectively. As of December 31, 2022 there was $19.1 million of total unrecognized compensation cost related to time-based unvested stock options, and the Company expects to recognize such amount over a remaining weighted-average period of 3.1 years.

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock for those stock options that had an exercise price lower than the fair value of the Company’s common stock.

Performance-Based Stock Options

The Company has granted stock options to certain employees to purchase shares of common stock that contain certain performance-based vesting criteria, primarily related to the achievement of certain development milestones related to IND acceptance, and the consummation of the Company’s IPO. The performance-based stock options were granted “at-the-money” and have a term of 10 years.

The fair value of each option grant under the performance share option plan was estimated on the date of grant using the same option valuation model used for time-based stock options above. Recognition of stock-based compensation expense associated with these performance-based stock options commences when the performance condition is considered probable of achievement, using management’s best estimates, which consider the inherent risk and uncertainty regarding the future outcomes of the milestones.

The following table summarizes the Company’s performance-based stock option activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
				(in years)
Outstanding at December 31, 2021	241,248	$	3.67	9.83	$	1,749
Granted	170,482	$	10.86


Outstanding at December 31, 2022	411,730	$	6.65	9.17	$	4,912
Vested and exercisable at December 31, 2022	121,160	$	5.11	9.07	$	1,632
Vested and expected to vest at December 31, 2022	411,730	$	6.65	9.17	$	4,912

Through December 31, 2022, the Company concluded that the achievement of the performance conditions for such awards, proof of concept and consummation of IPO were achieved, and compensation expense related to these awards were recognized. The Company concluded that the achievement of the remaining performance condition for such awards was not probable. The weighted average grant date fair value of the performance stock options awarded during the year ended December 31, 2022 was $9.55. As of December 31, 2022 there was $2.3 million of total unrecognized compensation cost related to performance-based stock options. As of December 31, 2021, there was $1.4 million of total unrecognized compensation cost related to performance-based stock options.

Restricted Common Stock Awards

The Company awarded restricted common stock to employees and non-employees under its 2019 Plan and may continue to award restricted common stock to employees and non-employees under the 2022 Plan. The fair value of each share of restricted common stock is based on the market price of the Company's common stock on the date of grant.

For a period of up to six months from a grantee’s termination, the Company has the right and option to repurchase unvested restricted common stock at the lower of (i) the original purchase price per share ($0.00004) or (ii) the fair market value per share as of the date of the Company elects to exercise its repurchase right. In May 2022, the Company repurchased 3,116 unvested shares of the restricted common stock at a price of $0.00004 per share, the original sale price, and the repurchased common shares were restored to the amount of unissued, authorized shares of common stock as of December 31, 2022.

During the years ended December 31, 2022 and 2021, the Company issued time-based restricted common stock and performance-based restricted common stock with vesting subject to certain performance conditions. Shares of restricted common stock granted to employees and directors are not deemed, for accounting purposes, to be outstanding until those shares have vested.

Each award type is discussed below.

Time-Based Restricted Common Stocks

The majority of the restricted common stock have time-based vesting conditions and vest over a four-year period, subject to the employee’s continued employment with, or service to, the Company on such vesting date. Compensation expense is recognized on a straight-line basis over the vesting period.

Time-Based Restricted Common Stock Awards

The following table summarizes the Company’s time-based restricted common stock activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Grant-Date Fair Value




Unvested restricted common stock at December 31, 2021	10,801,361	$	0.10
Issued	—	$	—
Vested	(5,775,167)	$	0.10
Repurchased	(11,160)	$	0.35
Unvested restricted common stock at December 31, 2022	5,015,034	$	0.10

The aggregate fair value of restricted common stock that vested during the period for the years ended December 31, 2022, 2021, and 2020 was $0.5 million, $0.6 million, and $0.1 million, respectively.

As of December 31, 2022, there was $0.3 million of total unrecognized compensation cost related to unvested time-based restricted common stock which the Company expects to recognize over a weighted-average period of 1.1 years.

Performance-Based Restricted Common Stock Awards

The Company has also granted performance‑based restricted common stock to certain executive officers and key persons of the Company with terms that allow the grantees to vest in a specific number of shares based upon the achievement of performance‑based milestones, primarily related to the dosing of a first patient in a Phase II or later-stage clinical trial or FDA approval of compound, proof of concept in a lead indication, IND acceptance and consummation of the Company’s IPO.

Share‑based compensation expense associated with the performance-based restricted common stock is recognized if the performance condition is considered probable of achievement using the Company’s best estimates of the time to vesting for the achievement of the performance‑based milestones. Each reporting period, the Company updates its assessment of the probability that the performance-based milestones will be achieved. The fair value of the restricted common stock was based on the fair market value of the Company’s common stock on the date of grant. As of December 31, 2022, the Company has concluded that the proof of concept and the consummation of the IPO performance obligations were achieved, and compensation expense related to the performance-based restricted common stock has been recorded. The Company concluded it was not probable that the remaining performance condition would be achieved and no compensation expense was recorded for this performance obligation. As of December 31, 2021 and 2020, the Company has concluded it was not probable that these performance conditions related to performance-based restricted common stock would be achieved, and as a result no compensation expense related to the performance-based restricted common stock has been recorded.

The following table summarizes the Company’s performance-based restricted common stock activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Grant-Date Fair Value




Unvested restricted common stock at December 31, 2021 (1)	4,553,223	$	0.10
Issued	—	$	—
Vested	(720,454)	$	0.18
Repurchased	—	$	—
Unvested restricted common stock at December 31, 2022	3,832,769	$	0.07
(1) Includes 3,472,545 shares granted to a co-founder in September 2019

As of December 31, 2022, there was $0.3 million of total unrecognized compensation cost related to unvested performance-based restricted common stock.

Stock-Based Compensation

The following table below summarizes the classification of the Company’s stock-based compensation expense related to stock options and restricted common stock awards in the consolidated statements of operations and comprehensive loss (in thousands):


	Year Ended December 31,
	2022		2021		2020

General and administrative	$	2,019	$	459	$	40
Research and development	4,440		1,287		351
	$	6,459	$	1,746	$	391

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Tax Disclosure

Income Taxes

For the years ended December 31, 2022, 2021, and 2020, the Company recorded a tax provision (benefit) of $(0.9) million, $(0.5) million, and $1.9 million respectively. The deferred provision for the year ended December 31, 2022 was attributable to the change in deferred tax liability associated with the unrealized gains on investments. The deferred provision for the year ended December 31, 2021 was attributable to the Company recording a valuation allowance on its deferred tax assets and liabilities due to the Company being in a net deferred tax asset position.

The components of income tax provision are as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Components of income tax provision
Current provision:
Federal	$	—	$	—	$	—
State	16		138		—
Total current provision	16		138		—
Deferred income tax provision (benefit):
Federal	(314)		(928)		1,332
State	(650)		304		535
Total deferred income tax provision (benefit)	(964)		(624)		1,867
Total provision for (benefit from) income taxes	$	(948)	$	(486)	$	1,867

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows:


	Year Ended December 31,
	2022			2021			2020
Rate Reconciliation
Federal income tax expense at statutory rate	21.0	%		21.0	%		21.0	%
State income taxes, net of federal benefit	7.7	%		3.5	%		(38.5)	%
Permanent differences	(0.9)	%	(1)	(9.6)	%	(1)	(148.5)	%	(1)
Tax credits	2.9	%		0.7	%		9.5	%
Other	—	%		(0.1)	%		(0.3)	%
Change in valuation allowance	(30.0)	%		(15.2)	%		35.8	%
Effective income tax rate	0.7	%		0.3	%		(121.0)	%

________________

(1)Permanent differences for the years ended December 31, 2022, 2021 and 2020 related to the change in fair value of Series A Preferred Stock tranche rights

Net deferred tax assets (liabilities) consisted of the following (in thousands):


	As of December 31,
	2022		2021
Deferred Tax Summary
Deferred tax assets:
U.S. and state net operating loss carryforwards	$	20,427	$	11,365
Tax credits	7,268		1,547
Depreciation and amortization	13,307		13,584
Accrual	1,649		639

Lease Liability	7,853		2,843
Capitalized research and development costs	19,974		—
Stock Compensation	122		—
Total deferred tax assets	$	70,600	$	29,978
Deferred tax liabilities:
Stock compensation	$	—	$	(136)
Mark to market adjustments	(34)		(34)
Unrealized gain/loss	(641)		(2,862)
Right of Use Asset	(8,072)		(2,936)
Total deferred tax liabilities	(8,747)		(5,968)
Valuation allowance	(62,132)		(25,253)
Net deferred tax assets (liabilities)	$	(279)	$	(1,243)

As of December 31, 2022, the Company had U.S. federal net operating loss carryforwards of $75.2 million, which may be available to reduce future taxable income, which do not expire. In addition, as of December 31, 2022, the Company had state net operating loss carryforwards of $73.3 million, which may be available to reduce future taxable income and expire at various times beginning in 2039. As of December 31, 2022, the Company also had federal and state research and development tax credit carryforwards of $4.9 million and $3.0 million, respectively, which may be available to reduce future tax liabilities and begin to expire in 2040 and 2036, respectively.

Utilization of the U.S. federal and state net operating loss carryforwards and research and development tax credit carryforwards may be subject to a substantial annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, and corresponding provisions of state law, due to certain ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of carryforwards that

can be utilized annually to offset future taxable income and tax liabilities. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain stockholders or public groups in the stock of a corporation by more than 50 percent over a three-year period. The Company has not conducted a study to assess whether a change of control has occurred or whether there have been multiple changes of control since inception due to the significant complexity and cost associated with such a study. If the Company has experienced a change of control, as defined by Section 382, at any time since inception, utilization of the net operating loss carryforwards or research and development tax credit carryforwards would be subject to an annual limitation, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term tax-exempt rate, and then could be subject to additional adjustments. Any limitation may result in expiration of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before their utilization. Further, until a study is completed by the Company and any limitation is known, no amounts are being presented as an uncertain tax position.

The Tax Cuts and Jobs Act (TCJA) requires taxpayers to capitalize and amortize research and development (“R&D”) expenditures under section 174 for tax years beginning after December 31, 2021. This rule became effective for the Company during the year and resulted in the capitalization of R&D costs of $80.7 million. The Company will amortize these costs for tax purposes over 5 years if the R&D was performed in the U.S. and over 15 years if the R&D was performed outside the U.S.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s history of cumulative net losses incurred since inception, expectation of future losses and lack of other positive evidence. As of December 31, 2020, the Company was in a deferred tax liability position due to the unrealized gain and therefore had released the valuation allowance and recorded an ending deferred tax liability balance. For the year ended December 31, 2021, the Company was in a net deferred tax asset position and therefore recorded a valuation allowance against the portion of its deferred tax assets that cannot be fully supported by the future reversal of existing deferred tax liabilities. For the year ended December 31, 2022, the Company was in a net deferred tax asset position and therefore recorded a valuation allowance against the portion of its deferred tax assets that cannot be fully supported by the future reversal of existing deferred tax liabilities. The Company has determined that the indefinite nature of the deferred tax liability related to its unrealized gain on its related party short-term investment can only support 80 percent of the federal deferred tax assets and none of the state deferred tax assets, resulting in a net deferred tax liability position at December 31, 2022 of $0.3 million. The Company reevaluates the positive and negative evidence at each reporting period.

For the year ended December 31, 2022, the valuation allowance increased primarily due to the increases in net operating loss carryforwards, capitalized research and development costs, and research and development tax credit carryforwards. The changes in the valuation allowance were as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Valuation allowance at beginning of year	$	25,253	$	—	$	552
Increases (decreases) recorded to income tax provision	$	36,879	$	25,253	$	(552)
Valuation allowance at end of year	$	62,132	$	25,253	$	—

The Company assesses the uncertainty in its income tax positions to determine whether a tax position of the Company is more likely than not to be sustained upon examination, including resolution of any related appeals of litigation processes, based on the technical merits of the position. For tax positions meeting the more-likely-than-not threshold, the tax amount recognized in the financial statements is reduced by the largest benefit that has a greater than 50 percent likelihood of being realized upon the ultimate settlement with the relevant taxing authority. As of December 31, 2022, the Company had not recorded any reserves for uncertain tax positions or related interest and penalties.

The Company files income tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. Since the Company is in a loss carryforward position, the Company is generally subject to examination

by the U.S. federal, state and local income tax authorities for all years in which a loss carryforward is available. As of December 31, 2022, there were no pending tax examinations. The Company is open to future tax examination under statute from 2019 to the present.

Concentrations of Credit Risk

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

Leases

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Leases

21 Erie Street, Cambridge, Massachusetts Lease

In March 2020, the Company entered into an operating lease to sublease office and laboratory space located at 21 Erie Street, Cambridge, Massachusetts. The lease commenced in March 2020 and was set to expire in March 2022. The lease agreement provides for escalating monthly rental payments with fixed costs for expenses and property taxes included in each payment. Upon the execution of the lease agreement the Company paid $0.1 million for the rental fee for the last month of the term and $0.1 million as a security deposit on the space, which is classified as other assets on the consolidated balance sheet as of December 31, 2020. Effective August 2020, the Company amended the sublease for additional office and laboratory space (the “1st Amendment”) with the lease commencement date in February 2021, and to extend the maturity of the sublease through June 2023. Upon the execution of the 1st Amendment, the Company paid a rental fee of $0.3 million to lease additional office space in addition to the last month’s rent of the lease and $0.3 million security deposit, which is classified as other assets on the consolidated balance sheet as of December 31, 2020. The lease was subsequently amended in October 2020 (the “2nd Amendment”) to shorten the maturity of the sublease through March 2023.

In May 2021, the Company amended (the “3rd Amendment”) the sublease for additional office and laboratory space (“Expanded Premises”). The lease commenced in December 2021 and expires in March 2023. Upon the execution of the 3rd Amendment the Company paid $0.2 million for the rental fee for the last month of the term and $0.2 million as a security deposit on the space, which is classified as other assets on the consolidated balance sheet as of December 31, 2021. In July 2021, the Company amended (the “4th Amendment”) the sublease for additional laboratory space (“Lab Space”) with a term of less than one year. The Lab Space lease is classified as a short-term lease and the Company will recognize lease payments as an expense on a straight-line basis over the term. In April 2022, the Company executed an extension (the “6th Amendment”) which extends the expiration date of the lease for a period of two years, from March 2023 to March 2025.

38 Sidney Street, Cambridge, Massachusetts Lease

In July 2021, the Company entered into a non-cancelable operating lease to sublease office space in Cambridge, Massachusetts. The lease commenced in August 2021 and expires in December 2024. The Company has a right to extend the lease for one additional six-month period at a market rate as determined by the sublandlord and agreed to by the Company. The option to extend the lease term is not included in the right-of-use asset and lease liability as it is not reasonably certain of being exercised. The lease requires the Company to share in prorated expenses and property taxes based on actual amounts incurred; those amounts are not fixed for future periods and, therefore, are not included in the measurement of the lease.

64 Sidney Street, Cambridge, Massachusetts Lease

In July 2021, the Company entered into a non-cancelable operating lease to sublease office space located at 64 Sidney Street, Cambridge, Massachusetts. The lease commenced on April 15, 2022 and will expire on April 15, 2025. The Company has a right to extend the lease for one additional six-month period at a market rate as determined by the sublandlord and agreed to by the Company. The lease requires the Company to share in prorated expenses and property taxes based on actual amounts incurred; those amounts are not fixed for future periods and, therefore, these amounts will not be included in the measurement of the lease.

60 First Street, Cambridge, Massachusetts Lease

In November 2021, the Company entered into a lease for office and laboratory space in Cambridge, Massachusetts. The Landlord is required to perform certain base building work prior to turning over the space to the Company to perform certain additional improvements, which is currently expected in 2023. The lease will then commence when the Company obtains control over the space with rental payments commencing 11 months later. The initial non-

cancelable term of the lease is ten years, and the Company has an option to extend the lease for an additional period of ten years with the rent during the option period being the then fair market rent. The Company secured the lease with a $13.1 million security deposit, which was recorded as restricted cash on the consolidated balance sheets as of December 31, 2022 and December 31, 2021.

480 Arsenal Street, Watertown, Massachusetts Lease

In May 2022, the Company entered into a non-cancelable operating lease to sublease office space located at 480 Arsenal Street, Watertown, Massachusetts. The lease commenced on May 13, 2022 and will expire on April 30, 2027. The lease requires the Company to share in prorated expenses and property taxes based on actual amounts incurred; those amounts are not fixed for future periods and, therefore, these amounts will not be included in the measurement of the lease. The Company secured the lease with a $0.4 million security deposit, which was recorded as restricted cash on the consolidated balance sheet as of December 31, 2022.

In conjunction with the lease, the Company entered into a sublease agreement to sublet a portion of the office space at 480 Arsenal Street Watertown, Massachusetts (the “Arsenal Street Sublease”). The Arsenal Street Sublease commenced in May, 2022 and will expire on April 30, 2025.

Summary of lease costs recognized under ASC 842

The following tables contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating leases for the years ended December 31, 2022 and December 31, 2021.

The components of lease cost under ASC 842 were as follows (in thousands):


	Year Ended December 31,
	2022		2021
Operating lease cost	$	10,999	$	4,457
Variable lease cost	1,111		222
Short-term lease cost	1,401		432
Total lease cost	$	13,511	$	5,111

In connection with the Arsenal Street Sublease, the Company recorded operating sublease income of $0.3 million for the year ended December 31, 2022 in other income (expense), net in the consolidated statements of operations and comprehensive loss. The Company was not relieved of its primary obligation under the operating lease as a result of the sublease.

The weighted-average remaining lease term and discount rate were as follows:


	Year Ended December 31,
	2022		2021
Weighted average remaining lease term (in years)	2.7 years		1.8 years
Weighted average discount rate	4.92	%	2.10	%

Future annual lease payments under non-cancelable operating leases as of December 31, 2022 were as follows (in thousands):


2023	$	11,963
2024	13,035
2025	3,510
2026	1,683
2027	566
Total future minimum lease payments	$	30,757


Less: imputed interest	(2,012)
	$	28,745

The lease for office space at 60 First Street, Cambridge, Massachusetts has not yet commenced and the expected date for which the Company obtains control of the space is currently uncertain but not expected to occur until the first half of 2023. The Company currently expects rent to commence 11 months after taking possession of the space, with full occupancy expected in 2024, for which the Company will pay approximately $208.7 million over the ten-year lease term. As the lease has not commenced as of December 31, 2022, the operating lease liabilities on the consolidated balance sheet through December 31, 2022 and the table above excludes any amounts related to this lease.

Disclosures under ASC 840

Prior to the adoption of ASC 842 on January 1, 2021, the Company recognized rent expense on a straight-line basis over the respective lease period. During the year ended December 31, 2020, rent expense was $1.0 million.

License and Collaboration Agreements	12 Months Ended
License and Collaboration Agreements	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License and Collaboration Agreements	License and Collaboration Agreements License Agreements with Broad Institute In September 2019, the Company entered into a license agreement with Broad Institute, Inc. (“Broad Institute”), and in May 2020, February 2021 and December 2022, the Company entered into amendments to this license agreement, for certain patents related to the field of prevention or treatment of human disease by editing or targeting DNA (the “Broad License Agreement”). Under the Broad License Agreement, Broad Institute granted the Company (i) an exclusive, worldwide license under the licensed patent rights solely to offer for sale, sell, have sold and import products covered by such licensed patent rights, or licensed products, solely for use within the Prime Broad Field (subject to certain specified limitations and exclusions with respect to certain applications), (ii) a non-exclusive, worldwide license under the licensed patent rights solely to make, have made, offer for sale, sell, have sold, and import licensed products solely for use in the Prime Broad Field, (iii) a non-exclusive, worldwide license under the licensed patent rights solely to make, have made, offer for sale, sell, have sold and import other products that are enabled by (a) the licensed patent rights or (b) the use of certain materials transferred to the Company by Broad Institute, solely for the prevention or treatment of human diseases and (iv) a non-exclusive, worldwide license solely for internal research. Further, with respect to DNA delivery or targeting applications covered by the licensed patent rights, the exclusive license granted to the Company by Broad Institute is limited only to “prime editor” products and specifically excludes applications relating to the production or processing of small or large molecules, including for the prevention or treatment of human disease. Under the Broad License Agreement, the Company also has the right to grant sublicenses to its affiliates and third parties, subject to certain requirements. The Company is obligated to use commercially reasonable efforts to develop, seek marketing approval for, and commercialize licensed products in the field. As partial consideration for the license, the Company made a upfront payment of $0.5 million to Broad Institute. Concurrently with the Broad License Agreement, the Company entered into a subscription agreement with Broad Institute (the “Broad Subscription Agreement”). Under the Broad Subscription Agreement, as additional consideration for the license, the Company issued 623,529 shares of common stock, with a fair value of $39,000, to Broad Institute, representing 5.0 percent of its then outstanding capital stock on a fully-diluted basis. The Broad Subscription Agreement also obligated the Company to issue additional shares of common stock to Broad Institute without additional consideration to maintain Broad Institute’s ownership of the Company at 5.0 percent on a fully-diluted basis, if at any time prior to the achievement of an equity financing up to $100.0 million, the Company issues additional securities that would cause Broad Institute shares of common stock to be less than 5.0 percent of the Company's outstanding capital stock on a fully-diluted basis (the “Anti-Dilution Obligation”). In connection with the fourth Series A Preferred Stock closing, the Anti-Dilution Obligation was settled in full (see Note 3). The Company also granted certain preemptive rights to Broad Institute, under which if after the Company has reached the financing threshold of $100.0 million, the Company proposes to offer or sell any new securities, then Broad Institute shall have the right to purchase from the Company the portion of such new securities that would allow Broad Institute to maintain its 5.0 percent ownership in the Company. The Company determined that the Anti- Dilution Obligation was required to be recorded as a liability because it was a freestanding instrument that would require the Company to transfer assets to settle the obligation and it is indexed to an obligation to contingently redeem the Company’s equity shares. Accordingly, the Company recorded a liability of $0.2 million equal to the Anti-Dilution Obligation fair value upon entering into the Broad Subscription Agreement. In April 2021, the Company exceeded the financing threshold with the fourth issuance of the Series A Preferred Stock (Note 6). In connection with the fourth closing of Series A Preferred Stock, Broad Institute purchased an additional 761,844 shares of Series A preferred stock, at a price of $1.00 per share for gross proceeds of $0.8 million, to maintain its 5.0 percent ownership in the Company. At the time of purchase, the Company’s Series A Preferred Stock had a fair value of $2.31 per share. Therefore, the Company recorded the difference between the purchase price and the fair value per share as additional paid-in capital as it represented a transaction with a stockholder due to Broad Institute’s existing ownership of the Company’s common stock. Under the Broad License Agreement, the Company is also required to use commercially reasonable efforts to develop licensed products in the Prime Broad Field in accordance with a development plan that the Company prepared and submitted to Broad Institute. The Company is also obligated to pay Broad Institute an annual license maintenance fee ranging from the low to mid five-figures dollar amount through the end of 2020 to a low six-figures dollar amount beginning in 2021. In addition, the Company is obligated to reimburse Broad Institute for its documented, out-of-pocket costs incurred while prosecuting and maintaining its licensed patent rights. Broad Institute is also entitled to receive clinical and regulatory milestone payments up to a total of $20.0 million per licensed product, depending on the patient population to be treated by the licensed product achieving the applicable milestone. If the Company undergoes a change of control at any time during the term of the Broad License Agreement, certain of the clinical and regulatory milestone payments will increase by a specified percentage. Broad Institute is also entitled to sales-based milestone payments up to a total of $54.0 million per licensed product, depending on the patient population to be treated by the licensed product achieving the applicable milestone. Broad Institute is entitled to lower payments to the extent the clinical and regulatory milestones or sales-based milestones are achieved by enabled products, rather than licensed products. Broad Institute is entitled to receive mid-single digit percentage royalties on net sales of licensed products, and low single-digit percentage royalties of enabled products. Royalties payable to Broad Institute are subject to customary offsets and reductions with respect to a product in a given country, to a floor. Royalties are due on a country-by-country and product-by-product basis beginning upon the first commercial sale of each product and ending on the latest of (i) the expiration of the last valid claim of a patent covering such product in such country, (ii) the period of regulatory exclusivity associated with such product in such country or (iii) 10 years after the first commercial sale of such product in such. Unless earlier terminated, the Broad License Agreement will remain in effect until the later of (i) the last to expire valid claim of an issued patent or pending patent application within the licensed patent rights covering the Company’s licensed products or (ii) the expiration of the last royalty term for a licensed product in a country. The Company can terminate the Broad License Agreement for convenience after a certain period of time following prior written notice to Broad Institute. Each party may terminate the Broad License Agreement for the other party’s uncured material breach within a specified time period following notice of such breach. Broad Institute may also immediately terminate the Broad License Agreement (i) to the extent the Company (or its affiliates or sublicensees) challenges a licensed patent right, (ii) upon the Company’s bankruptcy or insolvency or (iii) if the Company fails to procure and maintain insurance. The Company determined that the Broad License Agreement represented an asset acquisition of IPR&D assets with no alternative future use and recognized the aggregate acquisition cost as acquired IPR&D within research and development expense in the consolidated statement of operations and comprehensive loss. The acquisition did not qualify as a business combination as the acquisition did not include both an input and substantive processes, including an assembled workforce, that together contribute to the ability to create outputs. For the years ended December 31, 2022, 2021, and 2020, the Company recognized $0.1 million, $0.3 million, and $0.1 million, respectively, of research and development expense related to annual license maintenance fees. For the years ended December 31, 2022, 2021, and 2020, the Company recognized $1.4 million, $1.3 million, and $0.6 million, respectively, of general and administrative expenses related to its payment obligation with respect to out-of-pocket patent costs incurred by Broad Institute under the Broad License Agreement. As of December 31, 2022, 2021 and 2020, no milestone payments or royalties under the agreement had been paid or were due, and no specified milestones were deemed to be probable of achievement. In May 2020, February 2021 and December 2022, the Company amended the Broad License Agreement, in each case, to update or include additional licensed patent rights. Under the February 2021 amendment, as partial consideration for the addition of licensed patent rights relating to Prime Editing improvements, the Company paid Broad Institute an amendment fee of $0.1 million. Under the December 2022 amendment, as partial consideration for the addition of licensed patent rights relating to prime editing improvements, the Company recognized an amendment fee of $0.1 million as research and development expense. Option Agreement with Broad Institute In May 2021, the Company entered into an exclusive option agreement with Broad Institute (the “Broad Option Agreement), pursuant to which, Broad Institute granted to the Company an exclusive option to negotiate an amendment to the Broad License Agreement to include certain additional patent rights relating to Prime Editing improvements to the Company’s license thereunder (subject to certain specific limitations and exclusions with respect to certain applications) (the “Exclusive Option”). The Company paid an upfront fee of $0.1 million to Broad Institute under the agreement upon execution of the agreement, recognized as research and development expense for the year ended December 31, 2021. In December 2022, the Company exercised its option under the Broad Option Agreement to all of the patent rights covered by the Broad Option Agreement and in December 2022 executed the 2022 Broad License Agreement, as defined below, pursuant to which the Company was granted certain exclusive licenses and rights to such patent rights. 2022 License Agreement with Broad Institute In December 2022, the Company entered into a second license agreement with Broad Institute, Inc. (“Broad Institute”), (the “2022 Broad License Agreement”). Under the 2022 Broad License Agreement, Broad Institute grants to us certain rights and licenses under the patent rights it owns or controls related to MMR inhibition and prime editing improvements and specifically, (i) an exclusive, worldwide license under the licensed patent rights solely to offer for sale, sell, have sold and import products covered by such licensed patent rights, or licensed products, solely for use within the Prime Broad Field (subject to certain specified limitations and exclusions with respect to certain applications), (ii) a non-exclusive, worldwide license under the licensed patent rights solely to make, have made, offer for sale, sell, have sold, and import licensed products solely for use in the Prime Broad Field, (iii) a non-exclusive, worldwide license under the licensed patent rights solely to make, have made, offer for sale, sell, have sold and import other products that are enabled by (a) the licensed patent rights or (b) the use of certain materials transferred to us by Broad Institute, solely for the prevention or treatment of human diseases and (iv) a non-exclusive, worldwide license solely for internal research. Further, with respect to DNA delivery or targeting applications covered by the licensed patent rights, the exclusive license granted to us by Broad Institute is limited only to “prime editor” products and specifically excludes applications relating to the production or processing of small or large molecules, including for the prevention or treatment of human disease. Under the Broad License Agreement, the Company also has the right to grant sublicenses to its affiliates and third parties, subject to certain requirements. The Company is obligated to use commercially reasonable efforts to develop, seek marketing approval for, and commercialize licensed products in the field. Under the 2022 Broad License Agreement, we are required to use commercially reasonable efforts to develop licensed products in the Prime Broad Field in accordance with a development plan that we prepared and submitted to Broad Institute. The Company is also obligated to pay Broad Institute an annual license maintenance fee mid five-figures for the term of the Agreement. In addition, the Company is obligated to reimburse Broad Institute for its documented, out-of-pocket costs incurred while prosecuting and maintaining its licensed patent rights. Broad Institute is entitled to receive clinical and regulatory milestone payments for a limited category of licensed products or enabled products, which category we refer to as royalty-bearing products, up to a total of $2.0 million per royalty-bearing product depending on the patient population to be treated by the royalty bearing product achieving the applicable milestone. If the Company undergoes a change of control at any time during the term of the 2022 Broad License Agreement, certain of the clinical and regulatory milestone payments will increase by a specified percentage. Broad Institute is also entitled to sales-based milestone payments up to a total of $3.0 million royalty bearing product, depending on the patient population to be treated by the royalty bearing product achieving the applicable milestone. Broad Institute is entitled to lower payments to the extent the clinical and regulatory milestones or sales-based milestones are achieved by royalty-bearing products that are enabled products, rather than royalty-bearing products that are licensed products. Broad Institute is entitled to receive royalties of less than 0.2% on net sales of royalty bearing products, which shall be decreased for royalty bearing products that are enabled products. Royalties payable to Broad Institute are subject to limited customary offsets and reductions. On a country-by-country and product-by-product basis, the royalty term for a royalty bearing product in a country will terminate on the latest of: (i) the expiration of the last to expire valid claim of an issued patent or pending patent application within the licensed patent rights covering such product in such country, (ii) the period of regulatory exclusivity for such product in such country or (iii) ten (10) years after the first commercial sale of such royalty bearing product in such country. Unless earlier terminated, the 2022 Broad License Agreement will remain in effect until the later of (i) the last to expire valid claim of an issued patent or pending patent application within the licensed patent rights covering our licensed products or (ii) the expiration of the last royalty term for a royalty bearing product in a country. The Company can terminate the 2022 Broad License Agreement for convenience following prior written notice to Broad Institute. Each party may terminate the 2022 Broad License Agreement for the other party’s uncured material breach. Broad Institute may also immediately terminate the 2022 Broad License Agreement (i) to the extent we (or our affiliates or sublicensees) challenge a licensed patent right, (ii) upon our bankruptcy or insolvency or (iii) if we fail to procure and maintain insurance. The Company determined that the 2022 Broad License Agreement represented an asset acquisition of IPR&D assets with no alternative future use and will recognize the aggregate acquisition cost as acquired IPR&D within research and development expense in the consolidated statement of operations and comprehensive loss. The acquisition did not qualify as a business combination as the acquisition did not include both an input and substantive processes, including an assembled workforce, that together contribute to the ability to create outputs. No amounts were recorded for the year ended December 31, 2022. The Company recognized $0.2 million of research and development expense related to the acquired IPR&D from Broad Institute. As of December 31, 2022, no milestone payments or royalties under the agreement had been paid or were due, and no specified milestones were deemed to be probable of achievement. Broad Pledge In February 2021, the Company committed to donate $5.0 million to Broad Institute and Harvard University annually for 14 years, commencing in 2021 (the “Pledge”). The Pledge is intended to be used for research and development related to new genome editing technologies, for example Prime Editing, improve on existing genome-editing technologies, identify delivery mechanisms for these technologies and apply these technologies to the understanding and treatment of rare genetic diseases. The Company can terminate the Pledge at its discretion, subject to providing one year of funding from the date of termination. In August 2022, the Company amended and restated the Pledge to clarify that the funds may be used by the laboratory of David Liu, who is a member of Broad Institute and a faculty member at Harvard. The Company accounts for this Pledge as research and development expenses as it has access to certain data generated as a result of the Pledge. For both the years ended December 31, 2022 and 2021, the Company recognized $5.0 million of research and development expense in connection with the Pledge. Related Party Beam Collaboration Agreement In September 2019, the Company entered into a collaboration agreement with Beam (the “Beam Collaboration Agreement”) to collaborate on the research, development, manufacture and commercialization of certain Prime Editing products within a specified field and provide each other with access and licenses to certain proprietary technology to advance the other’s progress. Under the Beam Collaboration Agreement, each party agreed to provide each other with access to, and licenses under, certain technology, know-how and patent rights controlled by each party for a limited number of years after the effective date, known as the initial term, and certain improvements thereto. Under the Beam Collaboration Agreement, the Company granted Beam an exclusive (even as to the Company and its affiliates), worldwide license under (i) certain Prime Editing technology, know-how and patent rights that the Company controls during the initial term, and improvements thereto that the Company controls for a specified number of years following the initial term, and (ii) the Company’s interest in certain jointly-owned collaboration technology, in each case, solely to develop, make, have made, use, offer for sale, sell, import and commercialize licensed products only in the Beam field. Beam also granted to the Company certain non-exclusive, worldwide licenses under certain technology, know-how and patent rights, including under certain CRISPR or delivery-related technology, know-how and patent rights, that it controls during the initial term, and improvements thereto that Beam controls for a specified number of years following the initial term, solely to develop, make, have made, use, offer for sale, sell, import and commercialize products only in the Company’s field. As partial consideration for the Beam Collaboration Agreement, Beam agreed to pay the Company, upon its election to continue its collaboration with the Company on the first anniversary of the Beam Collaboration Agreement, $5.0 million worth of its own shares of common stock. Before and within a short period of time after the filing of an IND for a development candidate being developed under the Beam Collaboration Agreement, Beam has the option to designate up to a mid-single digit number of licensed products for which the Company is not permitted to exercise the profit share right (described below) (the “Beam Option”). Under the Beam Collaboration Agreement, a licensed product for which the Company has not exercised its profit share option or for which Beam has exercised the Beam Option is collectively referred to as “protected product.” Beam must exercise its option within 30 days following the filing of an IND for such product. Unless the Company exercises its profit sharing option for a licensed product, Beam is solely responsible for the development and commercialization of licensed products in the Beam field under the Beam Collaboration Agreement. If Beam exercises its option for a protected product, Beam will owe Prime a payment of $5.0 million if the product is developed for non-sickle cell disease or $10.0 million if the product is developed for sickle cell disease. On a licensed product-by-licensed product basis, the Company has the right to elect to share equally with Beam in the profits and losses in the United States for Beam’s licensed products. The Company may exercise such right for each licensed product within a specified period of time. Any such licensed product for which the Company exercises its right is referred to as a collaboration product. If the Company exercises such right, the Company agrees to share equally in the costs, profits and losses of each such collaboration product in the United States, rather than receiving milestones and royalties based on development and sales thereof by Beam in the United States. For clarity, the Company is still entitled to receive milestones and royalties on the development and sale of each such collaboration product outside the United States. The Company also has the right to elect, within a specified time period, at least one year prior to the expected filing of an NDA, to co-promote with Beam each collaboration product in the United States, in addition to sharing in the profits and losses. To the extent the Company exercises its co-promote option with respect to a given collaboration product, the Company and Beam must use commercially reasonable efforts to commercialize such collaboration product, in each case, in the Beam field in the major markets in which marketing authorization has been obtained. After the Company has exercised its right to profit share on a collaboration product, the Company is able to, at any time during the term of the Beam Collaboration Agreement, on a collaboration product-by-collaboration product basis, opt-out of the profit and loss share and co-promotion activities with respect to any collaboration product with prior written notice to Beam within a certain time period. The Company is entitled to receive development milestone payments from Beam on Beam’s development of protected products (which, for clarity, includes any licensed product for which the Company has not exercised its profit share option) and collaboration products. For protected products, the Company is entitled to receive up to a total of $35.5 million on a protected product-by-protected product basis based on Beam’s development of such protected product and, for collaboration products, up to a total of $17.8 million on a collaboration product-by-collaboration product basis based on Beam’s development of such collaboration product outside of the United States, in each case, with such amounts lowered if such licensed product achieves a given milestone for use in treating an orphan disease. The Company is also entitled to receive sales-based milestone payments from Beam based on net sales of licensed products. For protected products, the Company is entitled to receive up to a total of $84.5 million on a protected product-by-protected product basis based on net sales of such protected product worldwide, and, for collaboration products, up to a total of $42.3 million on a collaboration product-by-collaboration product basis based on net sales of collaboration products outside of the United States. The sickle cell disease product partnered with Beam is a licensed product under the Beam Collaboration Agreement. Beam has not designated this product as a protected product and the Company has not received any development or sales-based milestones with respect to Beam’s exploitation thereof. Beam is obligated to pay the Company tiered royalties ranging from a high-single digit percentage to a low double-digit percentage, but less than teens on net sales of protected products worldwide on a protected product-by-protected product basis and net sales of collaboration products outside of the United States on a collaboration product-by-collaboration product basis. The Company’s royalties are subject to customary offsets and reductions, to a floor that takes into account any royalties the Company is obligated to pay to its third-party licensors, including Broad Institute. In addition, certain of the rights licensed under the Beam Collaboration Agreement are sublicensed from third parties, and Beam agrees to reimburse the Company for certain payments the Company is required to make to its third-party licensors attributable to Beam’s exercise of any sublicense the Company grants to Beam, including payments it makes to Broad Institute under the Broad License Agreement. If the Company develops a product that is covered by the technology, know-how or patent rights that Beam licenses to the Company under the Beam Collaboration Agreement, which it refers to as a Prime product, the Company is obligated to pay to Beam a low single digit royalty on its worldwide net sales of such any product on a Prime product-by-Prime product and country-by-country basis, subject to certain customary reductions, to a floor. Unless earlier terminated in accordance with its terms, the Beam Collaboration Agreement will expire on the later of (a) expiration of the last royalty term for a product on which a party is obligated to pay royalties to the other party or (b) with respect to any collaboration product, the date on which neither party is developing or commercializing any such collaboration product in the United States. After expiration of the initial term, Beam can terminate the Beam Collaboration Agreement for convenience in its entirety, or on a licensed product-by-licensed product or subfield-by-subfield basis, with prior written notice to the Company. Each party may terminate the Beam Collaboration Agreement for (a) the other party’s uncured material breach, (b) upon the insolvency or bankruptcy of the other party or (c) immediately to the extent the other party (or its affiliates or sublicensees) challenges a patent right licensed to such party. In connection with the Beam Collaboration Agreement, concurrently in September 2019, Beam and the Company also entered into a mutual subscription agreement (“Beam Mutual Subscription Agreement”). Under the Beam Mutual Subscription Agreement, if Beam elected to continue its collaboration with the Company, on the first anniversary of the agreement the Company was obligated to grant Beam 1,608,337 shares of the Company’s common stock which represented 5.0 percent of the 100 million shares of Series A Preferred Stock that the Company had issued or committed to issue as of the effective date of the Beam Mutual Subscription Agreement. In September 2020, Beam elected to continue its collaboration with the Company and, in October 2020, as required by the terms under the Beam Mutual Subscription Agreement, the Company issued 1,608,337 shares of the Company’s common stock to Beam with a fair value of $0.2 million. For the year ended December 31, 2020, the Company recognized $5.2 million of collaboration revenue, which represents the net of the fair value of Beam’s common stock of $5.4 million as of the first anniversary of the Beam Collaboration Agreement, which was when the Company was entitled to the Beam shares, offset by the fair value of $0.2 million related to the 1,608,337 shares of the Company’s common stock required to be issued to Beam, which reflect a payment to the Company’s customer. The Company concluded that the Beam Collaboration Agreement and the Beam Mutual Subscription Agreement should be combined and treated as a single arrangement for accounting purposes as the agreements were entered into contemporaneously and in contemplation of one another. The Company determined that the combined agreements are accounted for under Topic 606, Revenue recognition. The Company identified the following performance obligations: (i) exclusive, worldwide license to certain Prime patents, (ii) non-exclusive, worldwide licenses to CRISPR technology and (iii) joint research committee participation. The Company also evaluated whether the Beam Option and the Company’s right to elect collaboration products in the Beam Collaboration Agreement represented material rights that would give rise to a performance obligation and concluded that neither the Beam Option nor the Company’s right to elect collaboration products convey a material right to Beam and therefore are not considered separate performance obligations within the Beam Collaboration Agreement. There have been no protected product or collaboration products to date. Under the Beam Collaboration Agreement, the Company is eligible to receive certain milestones and royalties regardless of whether any options are exercised, which are considered variable consideration. At each reporting period, the Company evaluates whether milestones are considered probable of being reached and, to the extent that a significant reversal would not occur in future periods, estimates the amount to be included in the transaction price. During the years ended December 31, 2022, 2021, and 2020 the Company did not receive any milestone payments and all variable consideration related to the Beam Collaboration Agreement remained fully constrained. The Company assessed the above promises and determined that the exclusive license for certain Prime products and non-exclusive licenses to CRISPR technology represent performance obligations within the scope of Topic 606. The exclusive license for certain Prime products and non-exclusive licenses to CRISPR technology are considered functional intellectual property and distinct from other promises under the contract. The exclusive license for certain Prime products and non-exclusive licenses to CRISPR technology are considered functional licenses that are distinct in the context of the Beam Collaboration Agreement as Beam can benefit from the licenses on its own or together with other readily available resources. As the exclusive license for certain Prime products and non-exclusive licenses to CRISPR technology are delivered at the same time, they are considered one performance obligation at contract inception. The joint research committee performance promise is immaterial in the context of the contract. The Company determined the transaction price under Topic 606 at the inception of the Beam Collaboration Agreement to be $5.2 million, consisting of the value of the Beam equity investment under the Beam Mutual Subscription Agreement, when measured at fair value, less the value of the Prime shares issued to Beam of $0.2 million. The shares Prime issued to Beam represents a payment to a customer and is therefore a reduction of the transaction price. The Company recognizes revenue for the license performance obligations at a point in time, that is upon the first anniversary of the effective date when Beam elected to continue its collaboration with the Company. As control of these licenses was transferred on this date, Beam could begin to use and benefit from the licenses, the Company recognized $5.2 million of license revenue during the year ended December 31, 2020 under the Beam Collaboration Agreement. There was no revenue recognized during the years ended December 31, 2022 or 2021. In September 2020, on the first anniversary of the Beam Collaboration Agreement, the Company was entitled to receive 200,307 shares of Beam common stock, which had a fair value of $5.4 million and which was recorded as related party collaboration revenue in the consolidated statements of operations and comprehensive loss at that time. In October 2020, Beam issued the shares of common stock to the Company at which time the common shares had a fair value of $5.5 million and which the Company recorded as related party short-term investments on the consolidated balance sheet. For the year ended December 31, 2020, the Company recognized a net gain of $0.1 million for the change in fair value of the Beam shares the Company was entitled to receive, which was recorded to other income (expense), net in the consolidated statements of operations and comprehensive loss. There was no change in fair value of $0.2 million related to the 1,608,337 shares of common stock issued by the Company to Beam, between the first anniversary date of the Beam Collaboration Agreement, in September 2020 and the issuance date of the shares of common stock in October 2020. For the years ended December 31, 2022, 2021, and 2020, the Company recognized an unrealized gain (loss) of $(8.1) million, $(0.4) million, and $10.9 million, respectively, for the change in fair value of the related party short-term investment consisting of Beam shares, which was recorded to other income (expense), net in the consolidated statements of operations and comprehensive loss. Additionally, in September 2019, in connection with the Beam Collaboration Agreement, the Company executed a letter agreement, as amended, to receive certain interim management and startup services from Beam through March 2021. The Company is obligated to reimburse Beam for out-of-pocket costs incurred in connection with performing the services. The Company concluded this does not represent a payment to a customer because it is a distinct service at standalone selling price. For the years ended December 31, 2021 and 2020, the Company paid $0.1 million and $0.1 million, respectively, for such services. As of December 31, 2020, there was $30,000 included within accounts payable and no amounts as of December 31, 2021. The agreement ended on March 31, 2021. Beam Sub-license Agreement On January 25, 2021, the Company entered into a sub-license agreement with Beam (the “Beam Sub-license Agreement”), under which Beam granted to the Company a non-exclusive, non-transferable, fully paid-up and royalty-free license to certain intellectual property that Beam has licensed from the Ohio State Innovation Foundation (the "OSIF") for internal research purposes only. The patent rights and other proprietary rights in or related to the patent rights are and will remain the exclusive property of the OSIF. There was no accounting impact of this amendment. Research Collaboration, Option and License Agreement with Myeloid In December 2021, the Company entered into a research collaboration and exclusive option agreement with Myeloid (the “Myeloid Agreement”). Under the Myeloid Agreement, the Company collaborates with Myeloid, a related party, on the research and development of LINE-1 retrotransposon technology. In connection with the Myeloid Agreement, the Company also entered into a subscription agreement with Myeloid under which the Company was obligated to issue an aggregate of 1,101,525 shares of its common stock as additional consideration for the license. Myeloid grants to the Company an exclusive option, exercisable during the research term and for 60 days thereafter, to obtain ownership of certain patent rights and know-how owned by Myeloid that relate to LINE-1 retrotransposon technology. If the Company exercises its option, in addition to assigning the Company ownership of the applicable patent rights and know-how, Myeloid also agrees to grant the Company certain exclusive and non-exclusive licenses, including to certain improvements and other enabling technology. Following the exercise of the Company’s option, the Company agrees to grant Myeloid, in addition to certain other licenses, an exclusive, worldwide license under the assigned patent rights and know-how to develop and commercialize products in the field of myeloid cells and myeloid cell engineering, or the Myeloid Field. As of December 31, 2022 and 2021, the Company has not exercised its option. Upon entering into the Myeloid Agreement, Myeloid was entitled to receive an upfront payment of $30.0 million in cash and an aggregate of 1,101,525 shares of the Company’s common stock, with a then fair value of $12.0 million, both of which Myeloid received in January 2022. If the research agreement meets its goals, then (i) during the research term, Myeloid is entitled to cash payments of up to $35.0 million in the aggregate upon the achievement of certain milestones reflecting the technology’s development; and (ii) if the Company exercises its option, the Company agrees to pay to Myeloid an option exercise fee of $80.0 million in cash, and shares of the Company’s common stock with a then fair value of $30.0 million. Additionally, if the research collaboration meets its goal and the Company exercises its option, and the Company is able to proceed with the development and commercialization of a product that is covered by (a) the patent rights or know-how subject to the Company’s option or (b) the patent rights or know-how developed by one or both of the parties during the research term related to LINE-1 retrotransposon technology, or, collectively, a Prime Product, Myeloid would be eligible to receive, for the first five Prime Products, development and regulatory milestone payments of up to $120.0 million on a Prime Product-by-Prime Product basis and sales-based milestone payments of up to $210.0 million on a Prime Product-by-Prime Product basis. Myeloid is also eligible to receive tiered low to mid single-digit percentage royalties on the Company’s annual aggregate global net sales of Prime Products on a Prime Product-by-Prime Product and country-by-country basis, subject to customary offsets and reductions to a floor. On a country-by-country and Prime Product-by-Prime Product basis, the period during which royalties will be paid will continue until the latest of (i) the expiration date of the last to expire valid claim of an issued patent or pending patent application within the patent rights subject to the Company’s option or the patent rights developed by one or both of the parties during the research term related to LINE-1 retrotransposon technology, in each case, covering the applicable Prime Product, (ii) loss of regulatory exclusivity for such Prime Product in such country, or (iii) ten (10) years after the first commercial sale of such Prime Product in such country. Following the exercise of the Company’s option and for a period of two years thereafter, Myeloid will have the right to select up to three targets, subject to certain exclusions, for the development and commercialization of products directed at such targets in all fields and the Company will be eligible to receive the development, regulatory and sales-based milestone payments and royalty payments as set forth above from Myeloid with respect to such products. Unless earlier terminated based on customary termination rights, the Myeloid Agreement will continue on a Prime Product-by-Prime Product and country-by-country basis until the expiration of the royalty term for such Prime Product in such country. If the Company exercises its option, neither party will have the right to terminate the Myeloid Agreement for any reason. The Company determined that the Myeloid Collaboration Agreement represented an asset acquisition of IPR&D assets with no alternative future use and recognized the aggregate acquisition cost as acquired IPR&D within research and development expense in the consolidated statement of operations and comprehensive loss. The acquisition did not qualify as a business combination as the acquisition did not include both an input and substantive processes, including an assembled workforce, that together contribute to the ability to create outputs. For the year ended December 31, 2021, the Company recorded $42.0 million of research and development expense related to the acquired IPR&D from Myeloid, which consisted of the initial upfront payment of $30.0 million and the $12.0 million fair value of common stock to be issued to Myeloid. In connection with the Company’s obligation to issue Myeloid shares of its common stock, the Company determined the fair value of the common stock to be issued based, in part, on the results obtained from a third-party valuation of the Company’s equity securities prepared as of December 24, 2021. As the Company had not issued the shares to Myeloid as of December 31, 2021, the Company recorded a $12.0 million related party forward contract liability based on the common stock fair value as of the date of the Myeloid Subscription Agreement. Further, there was no change in fair value of the shares from the date of the Myeloid Subscription Agreement to December 31, 2021. As such, the Company will recognize any future changes in fair value of the shares as other income (expense) through the date such shares are issued to Myeloid. In addition, as the upfront payment was not made as of December 31, 2021, the Company recorded the $30.0 million payment obligation within accrued expenses and other current liabilities on its consolidated balance sheets as of December 31, 2021. In January 2022, the Company made the $30.0 million payment and also issued the shares of its common stock to Myeloid. As of December 31, 2022 and 2021, no milestone payments under the agreement had been paid or were due, and no specified milestones were deemed to be probable of achievement.

Commitment and Contingencies	12 Months Ended
Commitment and Contingencies	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases The Company’s commitments under its operating leases are described in Note 10. License and Collaboration Agreements The Company entered into various license and collaboration agreements under which it is obligated to make fixed and contingent payments (see Note 11). 401(k) Plan The Company maintains a defined-contribution plan under Section 401(k) of the Internal Revenue Code of 1986 (the “401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. The Company will make matching contributions equal to 50% of the employee’s contributions, subject to a maximum of 6% of eligible compensation. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, 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 all board of directors 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. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any indemnification arrangements that could have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its consolidated financial statements as of December 31, 2022 and 2021. Legal Proceedings From time to time, the Company may become involved in legal proceedings or other litigation relating to claims arising in the ordinary course of business. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated. Significant judgment is required to determine both probability and estimated exposure amount. Legal fees and other costs associated with such proceedings are expensed as incurred. As of December 31, 2022 and 2021, the Company was not a party to any material legal proceedings or claims.

Net Loss per Share

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Net Loss per Share

The Company calculated basic and diluted net loss per share attributable to common stockholders using the two-class method required for companies with participating securities. The Company considers Series A Preferred Stock and Series B Preferred Stock to be participating securities as the holders are entitled to receive cumulative dividends as well as residuals in liquidation.

Under the two-class method, basic net loss per share available to common shareholders was calculated by dividing the net loss available to common shareholders by the weighted-average number of shares of common stock outstanding during the period. The net loss available to common shareholders was not allocated to the Series A Preferred Stock and Series B Preferred Stock as the holders of preferred stock did not have a contractual obligation to share in losses. Diluted net loss per share available to common shareholders was computed by giving effect to all potentially dilutive common stock equivalents outstanding for the period. For purposes of this calculation, preferred stock, unvested restricted stock and stock options to purchase common stock were considered common stock equivalents but had been excluded from the calculation of diluted net loss per share available to common shareholders as their effect was anti-dilutive. In periods in which the Company reports a net loss available to common shareholders, diluted net loss per share available to common shareholders is the same as basic net loss per share available to common shareholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

Net Loss Per Share


	Year Ended December 31,
	2022		2021		2020
Numerator:
Net loss	$	(121,821)	$	(165,367)	$	(3,410)
Accretion of preferred stock to redemption value	—		(1,468)		(1,645)
Cumulative dividend on preferred stock	(20,193)		(17,284)		—
Net loss attributable to common stockholders	$	(142,014)	$	(184,119)	$	(5,055)
Denominator:
Weighted-average common shares outstanding, basic and diluted	33,891,264		12,973,495		2,639,717
Net loss per share attributable to common stockholders, basic and diluted	$	(4.19)	$	(14.19)	$	(1.91)

For accounting purposes, the computation of basic net loss per share attributable to common stockholders, the amount of weighted-average common shares outstanding as of December 31, 2021, includes the impact of the

1,101,525 shares the Company was obligated to issue to Myeloid as of December 24, 2021 (see Note 11) and excludes all shares of unvested restricted common stock as such shares are not considered outstanding (see Note 8).


	Year Ended December 31,
	2022	2021	2020
Convertible preferred stock (as converted to common stock)	—	51,923,764	14,475,018
Stock Options to purchase common stock	4,365,995	3,002,803	—
Unvested restricted common stock awards	8,847,803	15,354,584	23,238,119
	13,213,798	70,281,151	37,713,137

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Founder Consulting Services For the years ended December 31, 2022, 2021, and 2020 the Company made payments of $0.2 million, $0.2 million and $0.2 million, respectively, to one of the Co-founder shareholders for scientific consulting and other expenses. As of December 31, 2022 and 2021, there were no amounts included within accounts payable. Beam Therapeutics The Company and Beam are parties to the Beam Collaboration Agreement and the Beam Mutual Subscription Agreement and have a common founder and one common board member (see Note 11). For the year ended December 31, 2020, the Company recognized a net gain of $0.1 million, related to change in the fair value of the Beam shares the Company was entitled to receive for the period from the first anniversary date of the Beam Collaboration agreement through the date on which the Beam shares were received in October 2020. Such unrealized gain (loss) was recorded as other income (expense), net within the consolidated statements of operations and comprehensive loss. For the years ended December 31, 2021 and 2020, the Company made payments of $0.1 million and $0.1 million, respectively, to Beam for general and administrative services pursuant to an agreement to receive certain interim management and startup services (see Note 11). The agreement ended on March 31, 2021 and for the year ended December 31, 2021, the Company made no payments for such services. As of December 31, 2022 and 2021, there were no amounts included within accounts payable. Newpath Partners In connection with the Series A and B Preferred Stock closings (see Note 6), the Company issued and sold 9,999,999 and 5,250,781 shares of Series A and B Preferred Stock, respectively, to Newpath Partners L.P. (“Newpath”), which is an affiliate to one of the Company’s board members, for an aggregate purchase price of $10.0 million and $23.0 million, respectively. These shares converted to 4,905,679 common shares in connection with the IPO. Myeloid Therapeutics In December 2021, the Company and Myeloid entered into the Myeloid Collaboration Agreement and Myeloid Subscription Agreement (see Note 11 and 15). The Company and Myeloid have one common board member, who is also an affiliate of Newpath, one of the Company’s holders of common Stock. For the year ended December 31, 2021, we recorded $42.0 million of research and development expense related to the acquired IPR&D from Myeloid, which consisted of the accrued initial upfront payment of $30.0 million and the $12.0 million fair value of common stock to be issued to Myeloid. For the year ended December 31, 2022, we paid $0.7 million to reimburse Myeloid for research and development expenses, and as of December 31, 2022, there was $0.3 million included within accrued expenses.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsFor its consolidated financial statements as of December 31, 2022 and for the year then ended, the Company has evaluated subsequent events through March 9, 2023, the date on which these consolidated financial statements were issued.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation

The accompanying consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary. Intercompany balances and transactions have been eliminated in consolidation. The accompanying consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“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 Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Use of Estimates

Cash and Cash Equivalents

Cash and Cash EquivalentsThe Company considers all highly liquid investments with an original maturity of three months or less at the time of initial purchase to be cash equivalents.

Short-term Investments and Related Party Short-Term Investment

Deferred Offering Costs

Deferred Offering CostsThe Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded as a reduction of the proceeds from the offering, either as a reduction of the carrying value of the preferred stock or in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss

Fair Value Measurements

Level 1 — Quoted prices in active markets for identical assets or liabilities.

Property and Equipment


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of remaining lease term or useful life

Impairment of Long-Lived Assets

Impairment of Long-Lived AssetsLong-lived assets consist primarily of property and equipment, and operating lease right-of-use assets. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. If such asset group is considered to be impaired, the impairment loss to be recognized is measured based on the excess of the carrying value of the impaired asset group over its fair value.

Leases

Segment Information

Classification and Accretion of Redeemable Convertible Preferred Stock And Preferred Stock Tranche Right Liability

Classification and Accretion of Redeemable Convertible Preferred Stock

Preferred Stock Tranche Right Liability

Revenue Recognition

The Company recognizes revenue in accordance with ASU 2014-09, Revenue from Contracts with Customers (Topic 606) and its related amendments, or, collectively, ASC 606.

Research and Development Expenses

Acquired In-Process Research and Development

Patent Costs

Contingencies

ContingenciesThe Company is subject to contingent liabilities, such as legal proceedings and claims, that arise in the ordinary course of business activities. The Company accrues for loss contingencies when losses become probable and are reasonably estimable. If the reasonable estimate of the loss is a range and no amount within the range is a better estimate, the minimum amount of the range is recorded as a liability on the consolidated balance sheets. The Company does not accrue for contingent losses that, in its judgment, are considered to be reasonably possible, but not probable; however, it discloses the range of reasonably possible losses.

Stock-Based Compensation

Comprehensive Loss

Comprehensive LossComprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the year ended December 31, 2020 there was no difference between net loss and comprehensive loss

Net Loss per Share Attributable to Common Stockholders

Income Taxes

Recently Adopted Accounting Pronouncements And Recently Issued Accounting Pronouncements Not Yet Adopted

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Schedule of Property and Equipment, Net


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of remaining lease term or useful life

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2022		2021
Laboratory equipment	$	19,422	$	5,274
Leasehold improvement	564		125
Furniture and fixture	235		144
Computer Hardware and Software	11		—
Construction in progress	1,608		—
	21,840		5,543
Less: Accumulated depreciation and amortization	(2,831)		(611)
	$	19,009	$	4,932

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis


	Fair Value Measurements at December 31, 2022
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	—	$	120,511	$	—	$	120,511
Short-term investment:
U.S. Treasury Bonds	—		98,467		—		98,467
Related party short-term investment:
Beam equity securities	7,834		—		—		7,834
	$	7,834	$	218,978	$	—	$	226,812


	Fair Value Measurements at December 31, 2021
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	—	$	49,450	$	—	$	49,450
Short-term investment:
U.S. Treasury bills and government securities	—		68,238		—		68,238
Related party short-term investment:
Beam equity securities	15,962		—		—		15,962
	$	15,962	$	117,688	$	—	$	133,650
Liabilities:
Related party forward contract liability	—		—		12,020		12,020
	$	—	$	—	$	12,020	$	12,020

Debt and Equity Securities

Short-term investments consisted of the following (in thousands):


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments:
U.S. Treasury Bonds	$	98,851	$	—	$	(384)	$	98,467
Related party short-term investment:
Beam equity securities	5,486		2,348		—		7,834
	$	104,337	$	2,348	$	(384)	$	106,301


	December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments:
U.S. Treasury bills and government securities	$	68,265	$	—	$	(27)	$	68,238
Related party short-term investment:
Beam equity securities	$	5,486	$	10,476	$	—	$	15,962
	$	73,751	$	10,476	$	(27)	$	84,200

Investments Classified by Contractual Maturity Date

The contractual maturities of the Company’s short-term investments in available-for-sale debt securities held were as follows (in thousands):


	December 31, 2022		December 31, 2021
Due within one year	$	98,467	$	68,238
	$	98,467	$	68,238

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation

A reconciliation of the related party forward contract liability measured and recorded at fair value on a recurring basis is as follows (in thousands):


	Forward Contract
Balance at December 31, 2020	$	—
Initial fair value of related party forward contract liability	$	12,020
Balance at December 31, 2021	$	12,020
Reclassification of related party forward contract liability upon settlement	$	(12,020)
Balance at December 31, 2022	$	—

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of remaining lease term or useful life

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2022		2021
Laboratory equipment	$	19,422	$	5,274
Leasehold improvement	564		125
Furniture and fixture	235		144
Computer Hardware and Software	11		—
Construction in progress	1,608		—
	21,840		5,543
Less: Accumulated depreciation and amortization	(2,831)		(611)
	$	19,009	$	4,932

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	December 31,
	2022		2021
Accrued Myeloid license fee–related party	$	—	$	30,000
Accrued employee compensation and benefits	6,529		2,364
Accrued professional fees	2,162		3,830
Lab-related supplies and services	1,548		719
Other	449		279
	$	10,688	$	37,192

Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2022

Temporary Equity Disclosure [Abstract]

Temporary Equity

As of December 31, 2021, the Preferred Stock consisted of the following (in thousands, except share amounts):


	December 31, 2021
	Preferred Stock Authorized	Preferred Stock Issued and Outstanding	Carrying Value		Liquidation Preference		Conversion price per share		Common Stock Issuable Upon Conversion
Series A Preferred Stock	115,761,842	115,761,842	$	196,157	$	125,000	$	3.1088	37,236,776
Series B Preferred Stock	45,658,957	45,658,957	$	199,643	$	210,814	$	13.6175	14,686,988
	161,420,799	161,420,799	$	395,800	$	335,814			51,923,764

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions

The following table presents, on a weighted-average basis, the assumptions used in the Black-Scholes option-pricing model to determine the fair value of stock options granted:


	December 31, 2022			December 31, 2021
Fair value per share of underlying common stock	$	7.34		$	7.54
Risk-free interest rate	3.0		%	1.2		%
Expected term (in years)	6.0			6.0
Expected volatility	74.77		%	75.27		%
Expected dividend yield	—		%	—		%

Share-Based Payment Arrangement, Option, Activity

The following table summarizes the Company’s time-based stock option activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
				(in years)




Outstanding at December 31, 2021	2,761,555	$	3.98	9.72	$	19,154
Granted	1,424,926	$	10.90
Exercised	(59,774)	$	3.67
Forfeited	(172,442)	$	5.05
Outstanding at December 31, 2022	3,954,265	$	6.43	9.02	$	48,030
Vested and exercisable at December 31, 2022	875,727	$	4.04	8.72	$	12,736
Vested and expected to vest at December 31, 2022	3,954,265	$	6.43	9.02	$	48,030

The following table summarizes the Company’s performance-based stock option activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
				(in years)
Outstanding at December 31, 2021	241,248	$	3.67	9.83	$	1,749
Granted	170,482	$	10.86


Outstanding at December 31, 2022	411,730	$	6.65	9.17	$	4,912
Vested and exercisable at December 31, 2022	121,160	$	5.11	9.07	$	1,632
Vested and expected to vest at December 31, 2022	411,730	$	6.65	9.17	$	4,912

Share-Based Payment Arrangement, Outstanding Award, Activity, Excluding Option

The following table summarizes the Company’s time-based restricted common stock activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Grant-Date Fair Value




Unvested restricted common stock at December 31, 2021	10,801,361	$	0.10
Issued	—	$	—
Vested	(5,775,167)	$	0.10
Repurchased	(11,160)	$	0.35
Unvested restricted common stock at December 31, 2022	5,015,034	$	0.10

The following table summarizes the Company’s performance-based restricted common stock activity for the year ended December 31, 2022:


	Number of Shares	Weighted-Average Grant-Date Fair Value




Unvested restricted common stock at December 31, 2021 (1)	4,553,223	$	0.10
Issued	—	$	—
Vested	(720,454)	$	0.18
Repurchased	—	$	—
Unvested restricted common stock at December 31, 2022	3,832,769	$	0.07
(1) Includes 3,472,545 shares granted to a co-founder in September 2019

Share-Based Payment Arrangement, Expensed and Capitalized, Amount


	Year Ended December 31,
	2022		2021		2020

General and administrative	$	2,019	$	459	$	40
Research and development	4,440		1,287		351
	$	6,459	$	1,746	$	391

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

The components of income tax provision are as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Components of income tax provision
Current provision:
Federal	$	—	$	—	$	—
State	16		138		—
Total current provision	16		138		—
Deferred income tax provision (benefit):
Federal	(314)		(928)		1,332
State	(650)		304		535
Total deferred income tax provision (benefit)	(964)		(624)		1,867
Total provision for (benefit from) income taxes	$	(948)	$	(486)	$	1,867

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows:


	Year Ended December 31,
	2022			2021			2020
Rate Reconciliation
Federal income tax expense at statutory rate	21.0	%		21.0	%		21.0	%
State income taxes, net of federal benefit	7.7	%		3.5	%		(38.5)	%
Permanent differences	(0.9)	%	(1)	(9.6)	%	(1)	(148.5)	%	(1)
Tax credits	2.9	%		0.7	%		9.5	%
Other	—	%		(0.1)	%		(0.3)	%
Change in valuation allowance	(30.0)	%		(15.2)	%		35.8	%
Effective income tax rate	0.7	%		0.3	%		(121.0)	%

________________

(1)Permanent differences for the years ended December 31, 2022, 2021 and 2020 related to the change in fair value of Series A Preferred Stock tranche rights

Schedule of Deferred Tax Assets and Liabilities

Net deferred tax assets (liabilities) consisted of the following (in thousands):


	As of December 31,
	2022		2021
Deferred Tax Summary
Deferred tax assets:
U.S. and state net operating loss carryforwards	$	20,427	$	11,365
Tax credits	7,268		1,547
Depreciation and amortization	13,307		13,584
Accrual	1,649		639

Lease Liability	7,853		2,843
Capitalized research and development costs	19,974		—
Stock Compensation	122		—
Total deferred tax assets	$	70,600	$	29,978
Deferred tax liabilities:
Stock compensation	$	—	$	(136)
Mark to market adjustments	(34)		(34)
Unrealized gain/loss	(641)		(2,862)
Right of Use Asset	(8,072)		(2,936)
Total deferred tax liabilities	(8,747)		(5,968)
Valuation allowance	(62,132)		(25,253)
Net deferred tax assets (liabilities)	$	(279)	$	(1,243)

Summary of Valuation Allowance


	Year Ended December 31,
	2022		2021		2020
Valuation allowance at beginning of year	$	25,253	$	—	$	552
Increases (decreases) recorded to income tax provision	$	36,879	$	25,253	$	(552)
Valuation allowance at end of year	$	62,132	$	25,253	$	—

Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Lease, Cost

The components of lease cost under ASC 842 were as follows (in thousands):


	Year Ended December 31,
	2022		2021
Operating lease cost	$	10,999	$	4,457
Variable lease cost	1,111		222
Short-term lease cost	1,401		432
Total lease cost	$	13,511	$	5,111

The weighted-average remaining lease term and discount rate were as follows:


	Year Ended December 31,
	2022		2021
Weighted average remaining lease term (in years)	2.7 years		1.8 years
Weighted average discount rate	4.92	%	2.10	%

Schedule of Operating Lease Liability

Future annual lease payments under non-cancelable operating leases as of December 31, 2022 were as follows (in thousands):


2023	$	11,963
2024	13,035
2025	3,510
2026	1,683
2027	566
Total future minimum lease payments	$	30,757


Less: imputed interest	(2,012)
	$	28,745

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted


	Year Ended December 31,
	2022		2021		2020
Numerator:
Net loss	$	(121,821)	$	(165,367)	$	(3,410)
Accretion of preferred stock to redemption value	—		(1,468)		(1,645)
Cumulative dividend on preferred stock	(20,193)		(17,284)		—
Net loss attributable to common stockholders	$	(142,014)	$	(184,119)	$	(5,055)
Denominator:
Weighted-average common shares outstanding, basic and diluted	33,891,264		12,973,495		2,639,717
Net loss per share attributable to common stockholders, basic and diluted	$	(4.19)	$	(14.19)	$	(1.91)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share


	Year Ended December 31,
	2022	2021	2020
Convertible preferred stock (as converted to common stock)	—	51,923,764	14,475,018
Stock Options to purchase common stock	4,365,995	3,002,803	—
Unvested restricted common stock awards	8,847,803	15,354,584	23,238,119
	13,213,798	70,281,151	37,713,137

Nature of the Business and Basis of Presentation (Details) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Oct. 12, 2022	Oct. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Subsequent Event [Line Items]
Stock issuance costs			$ 4,042	$ 1,086	$ 20
Accumulated deficit			(293,197)	$ (171,376)
Cash, cash equivalents, and short-term investments			$ 293,900
Reverse stock split		0.32167
Common Stock
Subsequent Event [Line Items]
Convertible preferred stock, number of shares converted into common stock (in shares) \| shares		51,923,758
Reverse stock split	0.32167
IPO
Subsequent Event [Line Items]
Sale of stock, number of shares issued (in shares) \| shares		11,721,456
Sale of stock, price per share (in dollars per share) \| $ / shares		$ 17.00
Proceeds from IPO		$ 180,200
Stock issuance costs		$ 19,100
Over-Allotment Option
Subsequent Event [Line Items]
Sale of stock, number of shares issued (in shares) \| shares		1,427,338

Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	1 Months Ended				12 Months Ended
	Oct. 31, 2022	Jan. 31, 2022	Dec. 31, 2021	Sep. 30, 2019	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2021
Summary of Significant Accounting Policies [Line Items]
Cash equivalents			$ 49,500,000		$ 120,500,000	$ 49,500,000
Restricted cash			13,125,000		13,496,000	13,125,000
Deferred offering costs			1,500,000		0	1,500,000
Impairment losses on long-lived assets					0	0
In-process research and development expense							$ 0
Reserves for uncertain tax positions or related interest and penalties			0		0	0	$ 0
Total operating lease liability					28,745,000			$ 2,700,000
Operating lease right-of-use lease assets			10,746,000		29,545,000	10,746,000		2,800,000
Prepaid rent								$ 100,000
Myeloid Therapeutics \| Collaborative Arrangement, Option and License Agreement
Summary of Significant Accounting Policies [Line Items]
Upfront payment			$ 30,000,000
Myeloid Therapeutics \| Collaborative Arrangement, License Agreement
Summary of Significant Accounting Policies [Line Items]
Fair value of stock issued		$ 12,000,000				12,000,000
Upfront cash consideration payable						30,000,000
Upfront payment		$ 30,000,000				30,000,000
Broad Institute \| Collaborative Arrangement, License Agreement
Summary of Significant Accounting Policies [Line Items]
Upfront payment				$ 500,000
Broad Institute \| Collaborative, Option Agreement
Summary of Significant Accounting Policies [Line Items]
Upfront cash consideration payable					$ 200,000
Upfront payment						$ 100,000
Series A Redeemable Convertible Preferred Stock
Summary of Significant Accounting Policies [Line Items]
Shares converted as part of IPO (in shares)	37,236,772
Series B Convertible Preferred Stock
Summary of Significant Accounting Policies [Line Items]
Shares converted as part of IPO (in shares)	14,686,986
Common Stock \| Myeloid Therapeutics \| Collaborative Arrangement, Option and License Agreement
Summary of Significant Accounting Policies [Line Items]
Stock issued to collaborating party (in shares)		1,101,525	1,101,525			1,101,525
Fair value of stock issued			$ 12,000,000	$ 30,000,000
Common Stock \| Broad Institute \| Collaborative Arrangement, License Agreement
Summary of Significant Accounting Policies [Line Items]
Stock issued to collaborating party (in shares)				623,529
Fair value of stock issued				$ 39,000

Summary of Significant Accounting Policies - Property and Equipment Useful Life (Details)	12 Months Ended
	Dec. 31, 2022
Laboratory equipment
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Furniture and fixture
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years

Fair Value Measurements - Hierarchy For Assets and Liabilities Measured At Fair Value On A Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Related party short-term investment	$ 7,834	$ 15,962
Total assets	226,812	133,650
Related party forward contract liability		12,020
Total liabilities		12,020
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	120,511	49,450
U.S. Treasury Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	98,467	68,238
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Related party short-term investment	7,834	15,962
Total assets	7,834	15,962
Related party forward contract liability		0
Total liabilities		0
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Level 1 \| U.S. Treasury Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Related party short-term investment	0	0
Total assets	218,978	117,688
Related party forward contract liability		0
Total liabilities		0
Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	120,511	49,450
Level 2 \| U.S. Treasury Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	98,467	68,238
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Related party short-term investment	0	0
Total assets	0	0
Related party forward contract liability		12,020
Total liabilities		12,020
Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Level 3 \| U.S. Treasury Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 0	$ 0

Fair Value Measurements - Schedule of Short-Term Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Equity Securities, FV-NI [Abstract]
Amortized Cost	$ 5,486	$ 5,486
Unrealized Gains	2,348	10,476
Unrealized Losses	0	0
Fair Value	7,834	15,962
Securities, amortized costs	104,337	73,751
Securities, unrealized gains	2,348	10,476
Securities, unrealized losses	(384)	(27)
Securities, fair value	106,301	84,200
U.S. Treasury Bonds
Debt Securities, Available-for-Sale [Abstract]
Amortized Cost	98,851	68,265
Unrealized Gains	0	0
Unrealized Losses	(384)	(27)
Fair Value	$ 98,467	$ 68,238

Fair Value Measurements - Contractual Maturities of Short-Term Investments in Available-For-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Due within one year	$ 98,467	$ 68,238
Total available-for-sale securities	$ 98,467	$ 68,238

Fair Value Measurements - Roll Forward (Details) - Forward Contract - 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	$ 12,020	$ 0
Initial fair value of related party forward contract liability		12,020
Reclassification of related party forward contract liability upon settlement	(12,020)
Ending balance	$ 0	$ 12,020

Fair Value Measurements - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Apr. 30, 2021	Nov. 30, 2020	Sep. 30, 2019	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of preferred stock tranche right liability				$ 0	$ 74,319	$ 10,904
Anti-dilution obligation, achievement threshold					100,000
Change in fair value of anti-dilution obligation				$ 0	$ 6,681	$ 700
Broad Institute
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Sale of stock, number of shares issued (in shares)					2,498,850
Convertible preferred stock, shares issued, value					$ 7,500
Series A Redeemable Convertible Preferred Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Sale of stock, number of shares issued (in shares)	70,761,842	34,999,999	10,000,001
Measurement Input, Share Price \| Series A Redeemable Convertible Preferred Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Preferred stock tranche right liability, measurement input, per share (in dollars per share)	$ 2.31	$ 0.73				$ 0.76
Measurement Input, Share Price \| Common Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Anti-dilution obligation, measurement input, per share (in dollars per share)					$ 3.02	$ 0.35

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 21,840	$ 5,543
Less: Accumulated depreciation and amortization	(2,831)	(611)
Property and equipment, net	19,009	4,932
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	19,422	5,274
Leasehold improvement
Property, Plant and Equipment [Line Items]
Total property and equipment	564	125
Furniture and fixture
Property, Plant and Equipment [Line Items]
Total property and equipment	235	144
Computer Hardware and Software
Property, Plant and Equipment [Line Items]
Total property and equipment	11	0
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 1,608	$ 0

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 2,224	$ 568	$ 43

Accrued Expenses and Other Current Liabilities (Details) - USD ($)
$ in Thousands

Dec. 31, 2022

Dec. 31, 2021

Payables and Accruals [Abstract]

Accrued Myeloid license fee–related party

$ 0

$ 30,000

Accrued employee compensation and benefits

6,529

2,364

Accrued professional fees

2,162

3,830

Lab-related supplies and services

1,548

719

Other

449

279

Accrued expenses and other current liabilities

^[1]

$ 10,688

$ 37,192

[1]	Includes related party amount of $0.3 million as of December 31, 2022. Includes related party amount of $30.0 million as of December 31, 2021. (see Note 14).

Convertible Preferred Stock - Narrative (Details)			1 Months Ended				12 Months Ended
Convertible Preferred Stock - Narrative (Details)	Oct. 12, 2022	Dec. 31, 2020 installment $ / shares	Oct. 31, 2022 shares	Apr. 30, 2021 USD ($) $ / shares shares	Nov. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($) $ / shares	Dec. 31, 2020 USD ($) installment $ / shares
Class of Stock [Line Items]
Reverse stock split			0.32167
Dividends, preferred stock							$ 0	$ 0	$ 0
Series A Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Shares converted as part of IPO (in shares) \| shares			37,236,772
Sale of stock, number of shares issued (in shares) \| shares				70,761,842	34,999,999	10,000,001
Sale of stock, price per share (in dollars per share) \| $ / shares				$ 1.00	$ 1.00	$ 1.00
Sale of stock, consideration received				$ 70,800,000	$ 35,000,000	$ 10,000,000
Stock issuance costs				41,000	46,000	$ 20,000
Obligation to purchase additional stock (in shares) \| shares						104,999,997
Obligation to purchase additional stock (in dollars per share) \| $ / shares						$ 1.00
Preferred stock, convertible, conversion ratio						0.1
Preferred stock tranche right liability				$ 91,800,000		$ 6,300,000
Sale of stock, consideration contributed by company					$ 9,500,000
Conversion price per share (in dollars per share) \| $ / shares		$ 3.1088					$ 3.1088	$ 3.1088	$ 3.1088
Percentage of required stockholders' outstanding shares		65.00%							65.00%
Number of installments \| installment		3							3
Convertible preferred stock, redeemable period		60 days
Increase in carrying amount of redeemable preferred stock							$ 0	$ 1,500,000	$ 1,600,000
Series A Redeemable Convertible Preferred Stock \| Measurement Input, Share Price
Class of Stock [Line Items]
Preferred stock tranche right liability, measurement input, per share (in dollars per share) \| $ / shares		$ 0.76		$ 2.31	$ 0.73				$ 0.76
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Shares converted as part of IPO (in shares) \| shares			14,686,986
Sale of stock, number of shares issued (in shares) \| shares				45,658,957
Sale of stock, price per share (in dollars per share) \| $ / shares				$ 4.3803
Sale of stock, consideration received				$ 200,000,000
Stock issuance costs				$ 400,000
Conversion price per share (in dollars per share) \| $ / shares		$ 13.6175					$ 13.6175	$ 13.6175	$ 13.6175
Common Stock
Class of Stock [Line Items]
Reverse stock split	0.32167

Convertible Preferred Stock - Preferred Stock at Balance Sheet Date (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Preferred Stock Authorized (in shares)		161,420,799
Preferred Stock Issued and Outstanding (in shares)		161,420,799
Carrying Value		$ 395,800
Liquidation Preference		$ 335,814
Common Stock Issuable Upon Conversion (in shares)		51,923,764
Redeemable convertible and convertible preferred stock, shares issued (in shares)		161,420,799
Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock Authorized (in shares)	0	115,761,842
Preferred Stock Issued and Outstanding (in shares)	0	115,761,842	45,000,000	10,000,001
Carrying Value	$ 0	$ 196,157	$ 31,136	$ 3,987
Liquidation Preference		$ 125,000
Conversion price per share (in dollars per share)	$ 3.1088	$ 3.1088	$ 3.1088
Common Stock Issuable Upon Conversion (in shares)		37,236,776
Redeemable convertible and convertible preferred stock, shares issued (in shares)	0	115,761,842
Series B Preferred Stock
Class of Stock [Line Items]
Preferred Stock Authorized (in shares)	0	45,658,957
Preferred Stock Issued and Outstanding (in shares)	0	45,658,957	0	0
Carrying Value	$ 0	$ 199,643	$ 0	$ 0
Liquidation Preference		$ 210,814
Conversion price per share (in dollars per share)	$ 13.6175	$ 13.6175	$ 13.6175
Common Stock Issuable Upon Conversion (in shares)		14,686,988
Redeemable convertible and convertible preferred stock, shares issued (in shares)	0	45,658,957

Common Stock (Details)	Dec. 31, 2022 vote shares	Dec. 31, 2021 shares
Equity [Abstract]
Number of votes per common share \| vote	1
Common stock reserved for conversion of preferred stock (in shares) \| shares	7,622,758	58,433,916

Stock-Based Compensation - Narrative (Details) - USD ($)		1 Months Ended	12 Months Ended
	Feb. 09, 2022	May 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Apr. 30, 2021	Dec. 31, 2019
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock reserved for conversion of preferred stock (in shares)			7,622,758	58,433,916
Share-based compensation expense			$ 6,459,000	$ 1,746,000	$ 391,000
Stock options granted (in shares)					0
Stock Options to purchase common stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)			6 years	6 years
Time-Based Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options outstanding (in shares)			3,954,265	2,761,555
Stock options granted (in shares)			1,424,926
Weighted-average grant-date fair value of stock options granted (in dollars per share)			$ 7.40	$ 1.89
Unrecognized compensation cost			$ 19,100,000
Unrecognized compensation costs, period of recognition (in years)			3 years 1 month 6 days
Performance-Based Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options outstanding (in shares)			411,730	241,248
Stock options granted (in shares)			170,482
Weighted-average grant-date fair value of stock options granted (in dollars per share)			$ 9.55
Unrecognized compensation cost			$ 2,300,000	$ 1,400,000
Expected term (in years)			10 years
Unvested restricted common stock awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issued (in dollars per share)		$ 0.00004	$ 0.00004
Repurchased stock (in shares)		3,116
Restricted Stock, Time-Based
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting period (in years)			4 years
Unrecognized compensation costs, period of recognition (in years)			1 year 1 month 6 days
Aggregate fair value or restricted common stock			$ 500,000	$ 600,000	$ 100,000
Unrecognized compensation expense			300,000
Restricted Stock, Performance-Based
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense			$ 300,000
2019 Equity Incentive Plan \| Stock Options to purchase common stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issuable under plan (in shares)						11,561,815	6,171,635
Shares remaining available for grant (in shares)			0	2,405,824
Percent of fair market value of common stock (in percent)			110.00%
Voting power (in percent)			10.00%
Expiration period (in years)			10 years
Award vesting period (in years)			4 years
2019 Equity Incentive Plan \| Stock Options to purchase common stock \| Share-Based Payment Arrangement, Tranche One
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights (in percent)			25.00%
2019 Equity Incentive Plan \| Stock Options to purchase common stock \| Share-Based Payment Arrangement, Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting period (in years)			36 months
2019 Equity Incentive Plan \| Share-Based Payment Arrangement, ISO Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expiration period (in years)			5 years
2022 Stock Option and Incentive Plan and 2019 Equity Incentive Plan \| Stock Options to purchase common stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock reserved for conversion of preferred stock (in shares)	8,041,688
2022 Stock Option and Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options outstanding (in shares)			435,334
2022 Stock Option and Incentive Plan \| Stock Options to purchase common stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Percentage of annual increase in shares reserved for future issuance	5.00%
Options issued (in shares)			435,334
2022 Employee Stock Purchase Plan \| Employee Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock reserved for conversion of preferred stock (in shares)	971,350
Percentage of annual increase in shares reserved for future issuance	1.00%
Additional shares allowable under plan (in shares)	971,350
Share-based compensation expense			$ 0

Stock-Based Compensation - Valuation Assumptions (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Fair value per share of underlying common stock	$ 7.34	$ 7.54
Risk-free interest rate	3.00%	1.20%
Expected term (in years)	6 years	6 years
Expected volatility	74.77%	75.27%
Expected dividend yield	0.00%	0.00%

Stock-Based Compensation - Time-Based Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Granted (in shares)			0
Time-Based Stock Options
Number of Shares
Beginning of period (in shares)	2,761,555
Granted (in shares)	1,424,926
Exercised (in shares)	(59,774)
Forfeited (in shares)	(172,442)
End of period (in shares)	3,954,265	2,761,555
Options vested and exercisable, end of period (in shares)	875,727
Options vested and expected to vest, end of period (in shares)	3,954,265
Weighted-Average Exercise Price
Beginning of the period (in dollars per share)	$ 3.98
Granted (in dollars per share)	10.90
Exercised (in dollars per share)	3.67
Forfeited (in dollars per share)	5.05
End of period (in dollars per share)	6.43	$ 3.98
Options vested and exercisable, end of period (in dollars per share)	4.04
Options vested and expected to vest, end of period (in dollars per share)	$ 6.43
Weighted-average remaining contractual term, outstanding (in years)	9 years 7 days	9 years 8 months 19 days
Weighted-average remaining contractual term, vested and exercisable (in years)	8 years 8 months 19 days
Weighted-average remaining contractual term, vested and expected to vest (in years)	9 years 7 days
Aggregate intrinsic value, outstanding	$ 48,030,000	$ 19,154,000
Aggregate intrinsic value, vested and exercisable	12,736,000
Aggregate intrinsic value, vested and expected to vest	$ 48,030,000
Options outstanding (in shares)	3,954,265	2,761,555
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 6.43	$ 3.98

Stock-Based Compensation - Performance-Based Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Granted (in shares)			0
Performance-Based Stock Options
Number of Shares
Beginning of period (in shares)	241,248
Granted (in shares)	170,482
End of period (in shares)	411,730	241,248
Options vested and exercisable, end of period (in shares)	121,160
Options vested and expected to vest, end of period (in shares)	411,730
Weighted-Average Exercise Price
Beginning of the period (in dollars per share)	$ 3.67
Granted (in dollars per share)	10.86
End of period (in dollars per share)	6.65	$ 3.67
Options vested and exercisable, end of period (in dollars per share)	5.11
Options vested and expected to vest, end of period (in dollars per share)	$ 6.65
Weighted-average remaining contractual term, outstanding (in years)	9 years 2 months 1 day	9 years 9 months 29 days
Weighted-average remaining contractual term, vested and exercisable (in years)	9 years 25 days
Weighted-average remaining contractual term, vested and expected to vest (in years)	9 years 2 months 1 day
Aggregate intrinsic value, outstanding	$ 4,912	$ 1,749
Aggregate intrinsic value, vested and exercisable	1,632
Aggregate intrinsic value, vested and expected to vest	$ 4,912

Stock-Based Compensation - Restricted Stock Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2019
Restricted Stock, Time-Based
Number of Shares
Beginning of period (in shares)	10,801,361
Issued (in shares)	0
Vested (in shares)	(5,775,167)
Repurchased (in shares)	(11,160)
End of period (in shares)	5,015,034
Weighted-Average Exercise Price
Beginning of period (in dollars per share)	$ 0.10
Issued (in dollars per share)	0
Vested (in dollars per share)	0.10
Repurchased (in dollars per share)	0.35
End of period (in dollars per share)	$ 0.10
Number of awards outstanding (in shares)	5,015,034
Restricted Stock, Performance-Based
Number of Shares
Beginning of period (in shares)	4,553,223
Issued (in shares)	0
Vested (in shares)	(720,454)
Repurchased (in shares)	0
End of period (in shares)	3,832,769
Weighted-Average Exercise Price
Beginning of period (in dollars per share)	$ 0.10
Issued (in dollars per share)	0
Vested (in dollars per share)	0.18
Repurchased (in dollars per share)	0
End of period (in dollars per share)	$ 0.07
Number of awards outstanding (in shares)	3,832,769
Restricted Stock, Performance-Based \| Co-Founder Shareholder
Weighted-Average Exercise Price
Number of awards outstanding (in shares)		3,472,545

Stock-Based Compensation - Stock-Based Compensation Classification (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	$ 6,459	$ 1,746	$ 391
General and administrative
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	2,019	459	40
Research and development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	$ 4,440	$ 1,287	$ 351

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Provision for (benefit from) income taxes	$ (948,000)	$ (486,000)	$ 1,867,000
Research and development costs capitalized		80,700,000
Net deferred tax assets (liabilities)	279,000	1,243,000
Reserves for uncertain tax positions or related interest and penalties	0	$ 0	$ 0
Domestic Tax Authority
Income Tax Disclosure [Line Items]
Operating loss carryforwards	75,200,000
Domestic Tax Authority \| Research Tax Credit Carryforward
Income Tax Disclosure [Line Items]
Tax credit carryforward	4,900,000
State and Local Jurisdiction
Income Tax Disclosure [Line Items]
Operating loss carryforwards	73,300,000
State and Local Jurisdiction \| Research Tax Credit Carryforward
Income Tax Disclosure [Line Items]
Tax credit carryforward	$ 3,000,000

Income Taxes - Components of Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current provision:
Federal	$ 0	$ 0	$ 0
State	16	138	0
Total current provision	16	138	0
Deferred income tax provision (benefit):
Federal	(314)	(928)	1,332
State	(650)	304	535
Total deferred income tax provision (benefit)	(964)	(624)	1,867
Total provision for (benefit from) income taxes	$ (948)	$ (486)	$ 1,867

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Schedule of Reconciliation of the Difference Between the Effective Income Tax Rate and the Federal Statutory Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal income tax expense at statutory rate	21.00%	21.00%	21.00%
Effective Income Tax Rate Reconciliation, Percent [Abstract]
State income taxes, net of federal benefit	7.70%	3.50%	(38.50%)
Permanent differences	(0.90%)	(9.60%)	(148.50%)
Tax credits	2.90%	0.70%	9.50%
Other	0.00%	(0.10%)	(0.30%)
Change in valuation allowance	(30.00%)	(15.20%)	35.80%
Effective income tax rate	0.70%	0.30%	(121.00%)

Income Taxes - Net Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
U.S. and state net operating loss carryforwards	$ 20,427	$ 11,365
Tax credits	7,268	1,547
Depreciation and amortization	13,307	13,584
Accrual	1,649	639
Lease Liability	7,853	2,843
Capitalized research and development costs	19,974	0
Stock Compensation	122	0
Total deferred tax assets	70,600	29,978
Deferred tax liabilities:
Stock compensation	0	(136)
Mark to market adjustments	(34)	(34)
Unrealized gain/loss	(641)	(2,862)
Right of Use Asset	(8,072)	(2,936)
Total deferred tax liabilities	(8,747)	(5,968)
Valuation allowance	(62,132)	(25,253)	$ 0	$ (552)
Net deferred tax assets (liabilities)	$ (279)	$ (1,243)

Income Taxes - Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Valuation Allowance [Roll Forward]
Valuation allowance at beginning of year	$ 25,253	$ 0	$ 552
Increases (decreases) recorded to income tax provision	36,879	25,253	(552)
Valuation allowance at end of year	$ 62,132	$ 25,253	$ 0

Leases - Narrative (Details) $ in Millions	1 Months Ended				12 Months Ended
Leases - Narrative (Details) $ in Millions	Jul. 31, 2021 tradingDay	May 31, 2021 USD ($)	Aug. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2020 USD ($)	May 31, 2022 USD ($)	Apr. 30, 2022	Nov. 30, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Rent expense						$ 1.0
21 Erie Street, Cambridge, Massachusetts Lease
Lessee, Lease, Description [Line Items]
Rental fee		$ 0.2	$ 0.3	$ 0.1
Security deposit		$ 0.2	$ 0.3	$ 0.1
Operating lease, term of contract (in years)	1 year							2 years
38 Sidney Street, Cambridge, Massachusetts Lease
Lessee, Lease, Description [Line Items]
Number of renewal options \| tradingDay	1
Operating lease, extension (in years)	6 months
64 Sidney Street, Cambridge, Massachusetts Lease
Lessee, Lease, Description [Line Items]
Number of renewal options \| tradingDay	1
Operating lease, extension (in years)	6 months
60 First Street, Cambridge, Massachusetts Lease
Lessee, Lease, Description [Line Items]
Security deposit									$ 13.1
Operating lease, extension (in years)									10 years
Commencement of rent payments (in years)									11 months
Term of contract, lease not yet commenced (in years)					10 years				10 years
Expected liability to be paid					$ 208.7
480 Arsenal Street, Watertown, Massachusetts Lease
Lessee, Lease, Description [Line Items]
Security deposit							$ 0.4
Sublease income					$ 0.3

Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Lease Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Lease, Cost [Abstract]
Operating lease cost	$ 10,999	$ 4,457
Variable lease cost	1,111	222
Short-term lease cost	1,401	432
Total lease cost	$ 13,511	$ 5,111

Leases - Weighted-Average Remaining Lease Term Discount Rate (Details)	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Weighted average remaining lease term (in years)	2 years 8 months 12 days	1 year 9 months 18 days
Weighted average discount rate	4.92%	2.10%

Leases - Schedule of Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Jan. 01, 2021
Lessee, Operating Lease, Liability, to be Paid [Abstract]
2023	$ 11,963
2024	13,035
2025	3,510
2026	1,683
2027	566
Total future minimum lease payments	30,757
Less: imputed interest	(2,012)
Total operating lease liability	$ 28,745	$ 2,700

License and Collaboration Agreements (Details)

1 Months Ended

2 Months Ended

12 Months Ended

Dec. 31, 2022

USD ($)

Jan. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

product

Apr. 30, 2021

USD ($)

$ / shares

Mar. 03, 2021

USD ($)

Feb. 28, 2021

USD ($)

Nov. 30, 2020

USD ($)

$ / shares

Oct. 31, 2020

USD ($)

Sep. 30, 2020

USD ($)

Sep. 30, 2019

USD ($)

$ / shares

Oct. 31, 2020

USD ($)

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

product

target

Dec. 31, 2020

USD ($)

$ / shares

Development, regulatory, and sales-based milestone and royalty payment eligibility, term, thereafter (in years)

2 years

Development, regulatory, and sales-based milestone and royalty payment eligibility, number of targets | target

General and administrative expense

^[1]

$ 86,725,000

$ 70,550,000

$ 2,980,000

29,819,000

13,924,000

3,162,000

Change in fair value of related party short-term investment

5,210,000

(8,128,000)

(391,000)

$ 10,867,000

$ 300,000

$ 30,000,000

300,000

30,000,000

^[2]

12,020,000

Series A Redeemable Convertible Preferred Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Sale of stock, number of shares issued (in shares) | shares

70,761,842

34,999,999

10,000,001

Sale of stock, price per share (in dollars per share) | $ / shares

$ 1.00

Sale of stock, consideration received

$ 70,800,000

$ 35,000,000

$ 10,000,000

Series A Redeemable Convertible Preferred Stock | Measurement Input, Share Price

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Preferred stock tranche right liability, measurement input, per share (in dollars per share) | $ / shares

$ 2.31

$ 0.73

$ 0.76

Series A Preferred Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Issuance of common stock as consideration for related party collaboration agreement (in shares) | shares

100,000,000

Broad Institute | Collaborative Arrangement, License Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Equity financing, threshold

$ 500,000

100,000,000

Anti-dilution obligation, liability

200,000

Clinical and regulatory milestone payments, per product

2,000,000

20,000,000

2,000,000

Sales-based milestone payments, per product

$ 3,000,000

$ 54,000,000

3,000,000

Royalties, term (in years)

10 years

General and administrative expense

100,000

300,000

$ 100,000

1,400,000

1,300,000

600,000

Amendment fee

$ 100,000

Broad Institute | Collaborative Arrangement, License Agreement | Common Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Stock issued to collaborating party (in shares) | shares

623,529

Outstanding capital stock issued (in percent)

$ 39,000

5.00%

Broad Institute | Collaborative Arrangement, License Agreement | Series A Redeemable Convertible Preferred Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Sale of stock, number of shares issued (in shares) | shares

761,844

Sale of stock, price per share (in dollars per share) | $ / shares

$ 1.00

Sale of stock, consideration received

$ 800,000

Broad Institute | Collaborative Arrangement, 2022 License Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

royalty percentage (in percent)

0.20%

Broad Institute | Collaborative, Option Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Upfront cash consideration payable

100,000

200,000

Broad Institute, Inc. and Harvard University | Collaborative Agreement, Pledge

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Pledge commitment term (in years)

5,000,000

Pledge commitment

$ 5,000,000

14 years

Beam Therapeutics

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Unrealized gain (loss)

100,000

Beam Therapeutics | Collaborative Arrangement, Related Party

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Profit share option, term to exercise (in days)

30 days

Variable consideration amount for development milestone, per protected product

$ 35,500,000

Variable consideration amount for development milestone, per collaboration product

17,800,000

Variable consideration amount for sales milestone, per protected product

84,500,000

Variable consideration amount for sales milestone, per collaboration product

42,300,000

Revenue, remaining performance obligation, variable consideration received

5,200,000

Revenue, remaining performance obligation

5,200,000

Unrealized gain (loss)

$ 0

100,000

Change in fair value of related party short-term investment

(8,100,000)

(400,000)

10,900,000

Reimbursement costs

100,000

$ 0

30,000

Beam Therapeutics | Collaborative Arrangement, Related Party | Non-Sickle Cell Disease

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Profit share option, amount

5,000,000

Beam Therapeutics | Collaborative Arrangement, Related Party | Sickle Cell Disease

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Profit share option, amount

$ 10,000,000

Beam Therapeutics | Collaborative Arrangement, Related Party | Common Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Stock issued to collaborating party (in shares) | shares

1,608,337

200,307

1,608,337

Outstanding capital stock issued (in percent)

$ 200,000

$ 5,400,000

5.00%

Stock issued by collaborating party

5,000,000

Stock consideration and collaboration revenue

$ 5,200,000

$ 5,500,000

$ 5,400,000

Myeloid Therapeutics

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Sale of stock, number of shares issued (in shares) | shares

1,101,525

Myeloid Therapeutics | Collaborative Arrangement, License Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

$ 30,000,000

$ 12,000,000

12,000,000

Upfront cash consideration payable

42,000,000

30,000,000

Unrealized gain (loss)

$ 300,000

300,000

12,000,000

Milestone payments

$ 0

Myeloid Therapeutics | Collaborative Arrangement, Option and License Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Sales-based milestone payments, per product

30,000,000

$ 210,000,000

Royalties, term (in years)

10 years

Option to obtain ownership, term to exercise (in days)

60 days

Technology development milestone payments

$ 35,000,000

Option exercise fee

$ 80,000,000

Development and regulatory milestone payments, number of products | product

Development and regulatory milestone payments, per product

$ 120,000,000

Myeloid Therapeutics | Collaborative Arrangement, Option and License Agreement | Common Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Stock issued to collaborating party (in shares) | shares

1,101,525