Entrada Therapeutics (TRDA) 10-Q 12 May 22 2022 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2022	Apr. 30, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	001-40969
Entity Registrant Name	ENTRADA THERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-3983399
Entity Address, Address Line One	6 Tide Street
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02210
City Area Code	857
Local Phone Number	520-9158
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	TRDA
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		31,365,567
Entity Central Index Key	0001689375
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 84,640	$ 291,064
Marketable securities	179,262	0
Prepaid expenses and other current assets	8,810	7,636
Total current assets	272,712	298,700
Property and equipment, net	7,197	6,261
Restricted cash	3,950	0
Right-of-use assets, operating leases	31,409	0
Other non-current assets	1,434	872
Total assets	316,702	305,833
Current liabilities:
Accounts payable	2,931	706
Accrued expenses and other current liabilities	4,524	6,013
Operating lease obligations, current portion	7,971	0
Total current liabilities	15,426	6,719
Operating lease obligations, non-current	23,885	0
Deferred rent, net of current portion	0	396
Total liabilities	39,311	7,115
Commitments and contingencies (Note 10)
Stockholders’ equity:
Common stock, par value $0.0001; 150,000,000 shares authorized; 31,360,983 shares issued and 31,264,451 shares outstanding as of March 31, 2022 and 31,336,092 shares issued and 31,224,336 shares outstanding as of December 31, 2021.	3	3
Additional paid‑in capital	394,263	392,384
Accumulated other comprehensive loss	(1,535)	0
Accumulated deficit	(115,340)	(93,669)
Total stockholders’ equity	277,391	298,718
Total liabilities and stockholders’ equity	$ 316,702	$ 305,833

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Common stock, par value per share (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares, authorized (in shares)	150,000,000	150,000,000
Common stock, shares, issued (in shares)	31,360,983	31,336,092
Common stock, shares, outstanding (in shares)	31,264,451	31,224,336

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 15,718	$ 6,223
General and administrative	6,433	2,170
Total operating expenses	22,151	8,393
Loss from operations	(22,151)	(8,393)
Other income:
Interest and other income, net	480	13
Total other income, net	480	13
Net loss	$ (21,671)	$ (8,380)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.69)	$ (6.67)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.69)	$ (6.67)
Weighted-average common shares outstanding, basic (in shares)	31,246,916	1,256,487
Weighted-average common shares outstanding, diluted (in shares)	31,246,916	1,256,487
Other comprehensive loss:
Unrealized loss on marketable securities	$ (1,535)	$ 0
Total other comprehensive loss	(1,535)	0
Total comprehensive loss	$ (23,206)	$ (8,380)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY - USD ($)	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid‑in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balances (in shares) at Dec. 31, 2020	85,299,885
Beginning Balances at Dec. 31, 2020	$ 81,658,000
Redeemable Convertible Preferred Stock
Issuance of redeemable convertible preferred stock, net of issuance costs (in shares)		53,522,099
Issuance of redeemable convertible preferred stock, net of issuance costs		$ 115,831,000
Ending Balances (in shares) at Mar. 31, 2021	138,821,984
Ending Balances at Mar. 31, 2021	$ 197,489,000
Beginning Balances (in shares) at Dec. 31, 2020			1,244,139
Beginning Balances at Dec. 31, 2020	(41,490,000)		$ 0	$ 1,021,000	$ 0	$ (42,511,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)			16,453
Issuance of common stock upon exercise of stock options	29,000			29,000		0
Vesting of restricted common stock (in shares)			4,326
Vesting of early exercised options (in shares)			6,529
Vesting of early exercised options	8,000			8,000
Stock‑based compensation	164,000			164,000
Other comprehensive loss	0
Net loss	(8,380,000)					(8,380,000)
Ending Balances (in shares) at Mar. 31, 2021			1,271,447
Ending Balances at Mar. 31, 2021	$ (49,669,000)		$ 0	1,222,000	0	(50,891,000)
Beginning Balances (in shares) at Dec. 31, 2020	85,299,885
Beginning Balances at Dec. 31, 2020	$ 81,658,000
Ending Balances (in shares) at Dec. 31, 2021	0
Ending Balances at Dec. 31, 2021	$ 0
Beginning Balances (in shares) at Dec. 31, 2020			1,244,139
Beginning Balances at Dec. 31, 2020	$ (41,490,000)		$ 0	1,021,000	0	(42,511,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of early exercised options (in shares)	111,756
Ending Balances (in shares) at Dec. 31, 2021			31,224,336
Ending Balances at Dec. 31, 2021	$ 298,718,000		$ 3,000	392,384,000	0	(93,669,000)
Ending Balances (in shares) at Mar. 31, 2022	0
Ending Balances at Mar. 31, 2022	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	24,891		24,891
Issuance of common stock upon exercise of stock options	$ 50,000			50,000
Vesting of early exercised options (in shares)	96,532		15,224
Vesting of early exercised options	$ 35,000			35,000
Stock‑based compensation	1,794,000			1,794,000
Other comprehensive loss	(1,535,000)				(1,535,000)
Net loss	(21,671,000)					(21,671,000)
Ending Balances (in shares) at Mar. 31, 2022			31,264,451
Ending Balances at Mar. 31, 2022	$ 277,391,000		$ 3,000	$ 394,263,000	$ (1,535,000)	$ (115,340,000)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Redeemable Convertible Preferred Stock
Stock issuance costs	$ 420

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (21,671)	$ (8,380)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	390	199
Stock‑based compensation expense	1,794	164
Amortization of premiums and discounts on marketable securities, net	142	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,670)	(66)
Right-of-use assets, operating leases	1,582	0
Other non-current assets	(562)	23
Accounts payable	2,061	(268)
Accrued expenses and other current liabilities	(1,526)	(510)
Operating lease liabilities	(1,531)	0
Deferred rent	0	502
Net cash used in operating activities	(20,991)	(8,336)
Cash flows from investing activities:
Purchases of property and equipment	(594)	(908)
Purchases of marketable securities	(182,653)	0
Maturities of marketable securities	1,714	0
Net cash used in investing activities	(181,533)	(908)
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	116,248
Proceeds from exercise of stock options	50	29
Proceeds from the early exercise of stock options	0	108
Net cash provided by financing activities	50	116,385
Net increase (decrease) in cash, cash equivalents, and restricted cash	(202,474)	107,141
Cash, cash equivalents, and restricted cash at beginning of period	291,064	39,045
Cash, cash equivalents, and restricted cash at end of period	88,590	146,186
Supplemental cash flow disclosures:
Deferred financing costs in accounts payable and accrued expenses	0	418
Purchases of lessor-owned assets in accrued expenses	370	0
Purchases of property and equipment included in accounts payable and accrued expenses	391	462
Right-of-use assets obtained in exchange for operating lease liabilities	32,991	0
Transfer of deposits for equipment from operating to investing cash flows	495	0
Vesting of options early exercised subject to repurchase	$ 35	$ 8

Nature of the Business

Nature of the Business	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	Nature of the Business Organization Entrada Therapeutics, Inc. (Entrada or the Company) aims to transform the lives of patients by establishing Endosomal Escape Vehicle (EEV TM ) therapeutics as a new class of medicines and aims to become the world’s foremost intracellular therapeutics company. The Company was incorporated in Delaware on September 22, 2016 and its principal offices are located in Boston, Massachusetts. Liquidity and Capital Resources Since its inception, the Company has devoted substantially all of its resources to its research and development efforts relating to its proprietary, highly versatile and modular EEV platform (EEV Platform), advancing development of its portfolio of programs and general and administrative support for these operations, including raising capital. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, technical risks associated with the successful research, development and manufacturing of therapeutic 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. Therapeutic 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 will require significant amounts of additional capital, adequate personnel and infrastructure. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. In accordance with Accounting Standards Codification (ASC) 205-40, Going Concern, the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. The Company has incurred losses since its inception, including losses of $21.7 million and $8.4 million for the three months ended March 31, 2022 and 2021, respectively. As of March 31, 2022, the Company had an accumulated deficit of $115.3 million. To date, the Company has funded its operations primarily through the sale of equity securities. The Company expects to continue to generate operating losses and negative operating cash flows for the foreseeable future. The Company expects that its cash, cash equivalents and marketable securities of $263.9 million as of March 31, 2022 will be sufficient to fund its operations and capital expenditure requirements for at least the next twelve months from the date of issuance of these condensed consolidated financial statements. The Company will need additional financing to support its continuing operations and pursue its business strategy and may pursue additional cash resources through a combination of equity offerings, debt financings, collaborations, strategic alliances, licensing, or other arrangements. The Company may be unable to raise additional funds or enter into such other agreements when needed or 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The significant accounting policies used in preparation of these condensed consolidated financial statements for the three months ended March 31, 2022 are consistent with those discussed in Note 2 to the consolidated financial statements included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2021 (Annual Report) , except as noted immediately below. Basis of Presentation The accompanying condensed consolidated financial statements are unaudited and 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 Update (ASU) of the Financial Accounting Standards Board (FASB). The condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements, except for the adoption of ASU No. 2016-02 Leases (Topic 842) , as discussed further in Recently Adopted Accounting Pronouncements and Note 11 Leases . Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted, as is permitted by GAAP. These condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position as of March 31, 2022, and results of operations for the interim periods ended March 31, 2022 and 2021 . The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the audited financial statements as of and for the years ended December 31, 2021 and 2020, and the notes thereto, included in the Company’s Annual Report. Restricted Cash Restricted cash represents collateral provided for a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate facilities located at One Design Center Place, Boston, Massachusetts. A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows (in thousands): March 31, 2022 December 31, 2021 Cash and cash equivalents $ 84,640 $ 291,064 Restricted cash 3,950 — Total cash, cash equivalents and restricted cash $ 88,590 $ 291,064 Marketable Securities Investments in marketable securities are classified as available-for-sale. Available-for-sale securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as a separate component of stockholders’ equity. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. All of the Company’s available-for-sale securities are available to the Company for use in current operations. As a result, the Company classified all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. Realized gains and losses are determined using the specific identification method and are included in other income. The Company reviews investments in marketable securities for other-than-temporary impairment whenever the fair value of the investment is less than the cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers whether it has an intent to sell, or whether it is more likely than not that the Company will be required to sell, the investment before recovery of the investment’s cost basis. Evidence considered in this assessment includes reasons for the impairment, the severity and duration of the impairment and changes in value subsequent to the end of the period. To date, the Company has not recorded any credit losses on its available-for-sale securities. Comprehensive Loss Comprehensive loss includes net loss and other comprehensive income (loss). For the three months ended March 31, 2022, comprehensive loss consists of net loss and changes in unrealized gains and losses on marketable securities. Comprehensive loss was equal to net loss for the three months ended March 31, 2021. Recently Adopted Accounting Pronouncements ASU No. 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which supersedes all existing lease guidance. This guidance offers specific accounting guidance for a lessee, a lessor and sale and leaseback transactions. The new standard requires lessees to recognize an operating lease with a term greater than one year on their balance sheets as a right-of-use asset and corresponding lease liability, measured at the present value of the lease payments. Lessees are required to classify leases as either finance or operating leases. If the lease is effectively a financed-purchase by the lessee, the lease is classified as a financing lease; otherwise the lease is classified as an operating lease. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. Topic 842 provides accounting guidance for transactions that meet specific criteria for a leaseback transaction. If the criteria are not met, the transaction is considered a “failed sale” and the transaction must be accounted for as a financing arrangement. For EGCs, such as the Company, ASU 2016-02, as amended, is effective for annual reporting periods beginning after December 15, 2021 and interim periods within those fiscal years, with early adoption permitted. Prior to January 1, 2022, the Company accounted for leases pursuant to 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 escalations, holidays and lease incentives, on a straight-line basis over the lease term. The difference between rent expense recorded and the amount paid was recorded as deferred rent. The Company classified deferred rent as current and non-current liabilities based on the portion of the deferred rent that was scheduled to mature within the next twelve months. Effective January 1, 2022, the Company adopted ASC 842 using the modified retrospective approach and utilizing the effective date as its date of initial application. At contract inception, the Company determines whether an arrangement contains a lease based on the unique facts and circumstances present in the arrangement. The lease is assessed for classification as either an operating or finance lease at the lease commencement date, defined as the date on which the leased asset is made available for use by the Company, based on the economic characteristics of the lease. The 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. The Company has elected to take advantage of the short-term lease exemption, which allows for only leases with a term greater than one year to be recognized on the condensed consolidated balance sheets as right-of-use assets, classified as non-current assets, and operating lease liabilities, classified as current and non-current liabilities. Operating lease expense is recognized on a straight-line basis over the lease term. Operating lease liabilities and their corresponding right-of-use assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments, which reflects the fixed rate at which the Company could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. To estimate its incremental borrowing rate, a credit rating applicable to the Company is estimated using a synthetic credit rating analysis since the Company does not currently have a rating agency-based credit rating. In transition to ASC 842, the Company utilized the remaining lease term of its leases in determining the appropriate incremental borrowing rates. Prospectively, the Company will adjust the right-of-use assets for straight-line rent expense or any incentives received and remeasure the lease liability at the net present value using the same incremental borrowing rate that was in effect as of the lease commencement or transition date. Components of a lease are split into three categories: lease components, non-lease components, and non-components. The fixed and in-substance fixed contract consideration (including any consideration related to non-components) are allocated based on the respective relative fair values to the lease components and non-lease components. The Company has elected to account for lease and associated non-lease components together as a single lease component for all underlying assets and allocate all of the contract consideration to the lease component only. Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. The Company assesses its right-of-use assets for impairment in a manner consistent with its assessment for long-lived assets held and used in operations. As a result of the adoption of ASC 842, the Company recorded (i) an operating lease liability of $33.4 million determined using an incremental borrowing rate as of the effective adoption date and (ii) an operating lease right-of-use asset of $33.0 million, net of the unamortized balance of prepaid/accrued rent as of the transition date. There was no impact to the Company’s results of operations and cash flows from operations. ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes (ASU 2019-12), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends certain aspects of the existing guidance to improve consistent application. For EGCs, such as the Company, ASU 2019-12 is effective beginning January 1, 2022, with early adoption permitted. The Company adopted ASU 2019-12 on January 1, 2022. The adoption of this standard did not have a material impact on the Company’s financial position or results of operations upon adoption.

Marketable Securities

Marketable Securities	3 Months Ended
	Mar. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities The following is a summary of the Company's investment portfolio at March 31, 2022 (in thousands). The Company did not have any marketable securities as of December 31, 2021. Amortized Cost Unrealized Gains Unrealized Losses Fair Value U.S. government agency securities and treasuries $ 95,545 $ — $ 304 $ 95,241 Corporate debt securities 22,882 — 239 22,643 Total securities with a maturity of one year or less $ 118,427 $ — $ 543 $ 117,884 U.S. government agency securities and treasuries 34,684 — 508 34,177 Corporate debt securities 27,686 — 484 27,201 Total securities with a maturity of one to two years $ 62,370 $ — $ 992 $ 61,378 Total available-for-sale securities $ 180,797 $ — $ 1,535 $ 179,262 As of March 31, 2022, the Company had 38 securities with a total fair market value of $179.3 million in an unrealized loss position, of which none were in a continuous unrealized loss position for more than twelve months. The Company believes that any unrealized losses associated with the decline in value of its securities is temporary and primarily related to the change in market interest rates since purchase, and believes that it is more likely than not that it will be able to hold its debt securities to maturity. Therefore, the Company anticipates a full recovery of the amortized cost basis of its debt securities at maturity. Securities are evaluated for impairment at the end of each reporting period. The Company did not record any impairment related to its available-for-sale securities during the three months ended March 31, 2022.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following tables present the Company’s fair value hierarchy for its assets 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 March 31, 2022 Level 1 Level 2 Level 3 Total Cash equivalents $ 84,390 $ — $ — $ 84,390 Marketable securities: U.S. government agency securities and treasuries — 129,418 — 129,418 Corporate bonds — 49,844 — 49,844 Total $ 84,390 $ 179,262 $ — $ 263,652 Fair Value Measurements at December 31, 2021 Level 1 Level 2 Level 3 Total Cash equivalents $ 290,814 $ — $ — $ 290,814 Total $ 290,814 $ — $ — $ 290,814

Property and Equipment, Net

Property and Equipment, Net	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net consisted of the following at March 31, 2022 and December 31, 2021 (in thousands): March 31, December 31, Laboratory equipment $ 6,773 $ 5,988 Furniture and fixtures 161 96 Computer equipment 43 37 Leasehold improvements 1,556 1,556 Construction in progress 470 — Total property and equipment 9,003 7,677 Less: Accumulated depreciation (1,806) (1,416) Property and equipment, net $ 7,197 $ 6,261 Depreciation expense for the three months ended March 31, 2022 and 2021 was $0.4 million and $0.2 million, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 2022
Accrued Expenses and Other Current Liabilities [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following at March 31, 2022 and December 31, 2021 (in thousands): March 31, December 31, Employee compensation and benefits $ 1,630 $ 4,077 External research and development expenses 1,616 1,032 General and administrative professional service expenses 744 419 Other 534 485 Total accrued expenses and other current liabilities $ 4,524 $ 6,013

Common Stock and Preferred Stoc

Common Stock and Preferred Stock	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Common Stock and Preferred Stock	Common Stock and Preferred Stock Common Stock As of March 31, 2022 and December 31, 2021, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue 150,000,000 shares of common stock, par value $0.0001 per share. Shares Reserved for Future Issuance The Company has reserved the following shares of common stock for future issuance as of: March 31, 2022 December 31, 2021 Exercise of outstanding stock options 4,412,667 3,461,870 Vesting of outstanding restricted stock 297,754 — Future awards under the 2021 Stock Option and Incentive Plan 2,818,786 2,843,255 Future awards under the 2021 Employee Stock Purchase Plan 591,055 278,762 Total shares of authorized common stock reserved for future issuance 8,120,262 6,583,887 Preferred Stock As of March 31, 2022 and December 31, 2021, the Company was authorized to issue 10,000,000 shares of undesignated preferred stock, $0.0001 par value, in one or more series and to fix the rights, preferences, privileges and restrictions thereof. As of March 31, 2022 and December 31, 2021, there were no shares of undesignated preferred stock issued or outstanding.

Stock Based Compensation

Stock Based Compensation	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Stock Based Compensation	Stock-Based Compensation 2021 Plan The total shares of common stock authorized for issuance under the 2021 Stock Option and Incentive Plan (2021 Plan) increased from 3,986,270 as of December 31, 2021 to 5,246,076 as of March 31, 2022 due to the automatic annual increase provision. 2021 Employee Stock Purchase Plan The total shares of common stock authorized for issuance under the 2021 Employee Stock Purchase Plan (2021 ESPP) increased from 278,762 as of December 31, 2021 to 591,055 as of March 31, 2022 due to the automatic annual increase provision within the 2021 ESPP. No offering periods have commenced under the 2021 ESPP. 2016 Plan The total shares of common stock authorized for issuance under the 2016 Plan as of March 31, 2022 and December 31, 2021 were 2,283,131 shares and 2,318,855 shares, respectively. Stock-Based Compensation Stock-based compensation expense recorded in the condensed consolidated statements of operations is as follows (in thousands): Three Months Ended March 31, 2022 2021 Research and development expenses $ 704 $ 56 General and administrative expenses 1,090 108 Total $ 1,794 $ 164 Stock Option Valuation 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 during the three months ended March 31, 2022 and 2021: March 31, March 31, Risk‑free interest rate 1.61 % 0.63 % Expected volatility 70 % 76 % Expected dividend yield — — Expected term (in years) 6.06 6.04 Early Exercise of Unvested Stock Options Shares purchased by employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be outstanding shares until those shares vest according to their respective vesting schedules. Cash received from employee exercises of unvested options is included in current liabilities on the balance sheet. Amounts recorded are reclassified to common stock and additional paid-in capital as the shares vest. Vesting can occur in the year of exercise and thereafter. There were 96,532 and 111,756 unvested shares related to early exercises of stock options as of March 31, 2022 and December 31, 2021, respectively. As of each of March 31, 2022 and December 31, 2021, the liability associated with the unvested early exercise of stock options was $0.3 million. Stock Options The following table summarizes the Company’s stock option activity during the three months ended March 31, 2022: Number of Weighted‑ Outstanding as of December 31, 2021 3,461,870 $ 10.38 Granted 999,315 11.67 Exercised (24,891) 2.00 Forfeited (23,627) 10.73 Outstanding as of March 31, 2022 4,412,667 $ 10.72 Exercisable as of March 31, 2022 (1) 2,385,606 $ 6.25 (1) This represents the number of vested and unvested options exercisable as of March 31, 2022. The weighted-average grant-date fair value of stock options granted during the three months ended March 31, 2022 and 2021 was $7.39 per share and $1.61 per share, respectively. As of March 31, 2022, there was $26.4 million of unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted-average period of 2.2 years. Restricted Stock Units During the three months ended March 31, 2022, restricted stock units (RSUs) were granted to employees with vesting conditions based on continued service over time. Accordingly, stock-based compensation expense for such awards is recognized using a straight-line attribution model over the vesting term of each RSU. The fair value of each RSU is based on the closing price of the Company's common stock on the date of grant. A summary of restricted stock activity during the three months ended March 31, 2022 is as follows : Shares Weighted‑ Unvested as of December 31, 2021 — $ — Issued 302,279 11.57 Forfeited (4,525) 11.57 Unvested as of March 31, 2022 297,754 $ 11.57 As of March 31, 2022, there was $3.4 million of unrecognized stock-based compensation expense related to restricted stock that is expected to vest. These costs are expected to be recognized over a weighted-average remaining vesting period of 3.6 years.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income TaxesDeferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company's commitments, including significant license agreements, are disclosed in Note 9 Commitments and Contingencies in the audited financial statements for the year ended December 31, 2021, and notes thereto, included in the Company’s Annual Report. Since the date of those financial statements, there have been no changes to its commitments except those discussed in Note 11 Leases .

Leases

Leases	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Leases	Leases The Company’s operating lease activity is comprised of non-cancelable facility leases for office and laboratory space in Boston, Massachusetts. In February 2020, the Company entered into an operating lease for 26,235 square feet of office and laboratory space in Boston, Massachusetts. In June 2021, the Company entered into amendments to the operating lease for 8,631 square feet of additional office and laboratory space at its location in Boston, Massachusetts. The terms of the amendments begin between July 2021 and March 2022 and run co-terminus with the existing lease. The Company has the option to terminate the lease and amendments after November 30, 2023 without penalty. Consistent with the conclusion under ASC 840, it is not probable that the Company will exercise this option to terminate the lease early and, therefore, lease payments through November 2025 are included in the right-of-use asset and lease liabilities in the condensed consolidated balance sheets. The Company paid a security deposit of $0.8 million, which is recorded as a component of other non-current assets in the accompanying condensed consolidated balance sheets. The components of operating lease cost were as follows (in thousands): Three Months Ended March 31, 2022 Operating lease cost $ 1,890 Variable lease cost — Total lease cost $ 1,890 Supplemental information related to operating leases was as follows: Other information Three Months Ended March 31, 2022 Operating cash flows used for operating leases (in thousands) $ 1,839 Weighted average remaining lease term 3.7 years Weighted average discount rate 3.81% Future payments due under operating leases as of March 31, 2022 were as follows (in thousands): Maturity of Lease Liability As of March 31, 2022 2022 (excluding the three-months ended March 31, 2022) $ 6,735 2023 9,219 2024 9,494 2025 8,650 Thereafter — Total lease payments $ 34,098 Less: imputed interest (2,242) Present value of operating lease liabilities $ 31,856 On March 16, 2022, the Company and IDB 17-19 Drydock Limited Partnership, as landlord (Landlord), entered into a lease agreement (IDB Lease) with respect to approximately 81,442 square feet of office and laboratory space (Premises) in Boston, Massachusetts, which, when available for occupancy, will become the Company’s new consolidated headquarters location and supplement its existing space in Massachusetts. The Premises have not been made available to the Company as of March 31, 2022 and the lease is therefore excluded from the table above, as the IDB Lease has not commenced. The term of the IDB Lease commences the date upon which the Landlord tenders possession of the Premises to the Company following the Landlord’s substantial completion of the initial build-out of the Premises (Commencement Date) and shall continue for a period of approximately 10 years, unless earlier terminated in accordance with the terms of the IDB Lease (Lease Term). The Company has (i) the option to extend the Lease Term for an additional period of five (5) years, and (ii) a right of first offer on adjacent space to the Premises, subject to the terms and conditions of the IDB Lease. As these options are not reasonably certain of occurring, they will not be included in the initial calculation of the Company's right-of-use asset upon lease commencement. The initial fixed rental rate is $0.5 million per month, which is for a 12 month period during which the base rent is payable for 65,000 square feet, and will increase 3% per annum thereafter for the entire 81,442 square feet leased. Base rent becomes due upon the earlier of (i) the Company’s occupancy of the Premises, or (ii) 10 months following the Commencement Date, provided that in the event the Landlord’s initial build-out of the Premises is not complete on such date, base rent becomes due upon substantial completion of such initial build-out. Under the terms of the IDB Lease, the Landlord will provide an allowance in an amount not to exceed $19.5 million (calculated at a rate of $240.00 per rentable square foot of the Premises) toward the cost of completing the initial build-out of the Premises, which allowance is reflected in the base rent. In addition, the Company has the right to require the Landlord to provide an additional contribution in an amount not to exceed $1.6 million (calculated at a rate of $20.00 per rentable square foot of the Premises) toward the cost of additional improvements to the Premises, which amount shall be repaid by the Company in an amount of equal monthly payments of principal and interest as would be necessary to repay a loan in the full amount of the additional contribution used by the Company, subject to an 8% annual interest charge, on a level direct reduction basis over a 120 month period. The Company will be required to pay its share of operating expenses, taxes and any other expenses payable under the IDB Lease. In connection with the execution of the IDB Lease, the Company executed a $3.9 million cash-collateralized letter of credit, which may be reduced in the future subject to reduction requirements specified in the IDB Lease therein. The letter of credit is classified as restricted cash on the Company's condensed consolidated balance sheets.

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended March 31, 2022 2021 Numerator: Net loss attributable to common stockholders $ (21,671) $ (8,380) Denominator: Weighted‑average common shares outstanding, basic and diluted 31,246,916 1,256,487 Net loss per share attributable to common stockholders, basic and diluted $ (0.69) $ (6.67) The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended March 31, 2022 2021 Redeemable convertible preferred stock (as converted to common stock) — 19,185,183 Unvested restricted common stock 297,754 7,211 Unvested shares from early exercises 96,532 76,209 Stock options to purchase common stock 4,412,667 1,568,665 4,806,953 20,837,268

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the condensed consolidated financial statements to provide additional evidence for certain estimates or to identify matters that require additional disclosure. The Company has concluded that no subsequent events have occurred that require disclosure.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements are unaudited and 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 Update (ASU) of the Financial Accounting Standards Board (FASB). The condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements, except for the adoption of ASU No. 2016-02 Leases (Topic 842) , as discussed further in Recently Adopted Accounting Pronouncements and Note 11 Leases . Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted, as is permitted by GAAP. These condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position as of March 31, 2022, and results of operations for the interim periods ended March 31, 2022 and 2021 . The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the audited financial statements as of and for the years ended December 31, 2021 and 2020, and the notes thereto, included in the Company’s Annual Report.
Restricted Cash	Restricted CashRestricted cash represents collateral provided for a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate facilities located at One Design Center Place, Boston, Massachusetts.
Marketable Securities	Marketable Securities Investments in marketable securities are classified as available-for-sale. Available-for-sale securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as a separate component of stockholders’ equity. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. All of the Company’s available-for-sale securities are available to the Company for use in current operations. As a result, the Company classified all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. Realized gains and losses are determined using the specific identification method and are included in other income. The Company reviews investments in marketable securities for other-than-temporary impairment whenever the fair value of the investment is less than the cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers whether it has an intent to sell, or whether it is more likely than not that the Company will be required to sell, the investment before recovery of the investment’s cost basis. Evidence considered in this assessment includes reasons for the impairment, the severity and duration of the impairment and changes in value subsequent to the end of the period. To date, the Company has not recorded any credit losses on its available-for-sale securities.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss and other comprehensive income (loss). For the three months ended March 31, 2022, comprehensive loss consists of net loss and changes in unrealized gains and losses on marketable securities. Comprehensive loss was equal to net loss for the three months ended March 31, 2021.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements ASU No. 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which supersedes all existing lease guidance. This guidance offers specific accounting guidance for a lessee, a lessor and sale and leaseback transactions. The new standard requires lessees to recognize an operating lease with a term greater than one year on their balance sheets as a right-of-use asset and corresponding lease liability, measured at the present value of the lease payments. Lessees are required to classify leases as either finance or operating leases. If the lease is effectively a financed-purchase by the lessee, the lease is classified as a financing lease; otherwise the lease is classified as an operating lease. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. Topic 842 provides accounting guidance for transactions that meet specific criteria for a leaseback transaction. If the criteria are not met, the transaction is considered a “failed sale” and the transaction must be accounted for as a financing arrangement. For EGCs, such as the Company, ASU 2016-02, as amended, is effective for annual reporting periods beginning after December 15, 2021 and interim periods within those fiscal years, with early adoption permitted. Prior to January 1, 2022, the Company accounted for leases pursuant to 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 escalations, holidays and lease incentives, on a straight-line basis over the lease term. The difference between rent expense recorded and the amount paid was recorded as deferred rent. The Company classified deferred rent as current and non-current liabilities based on the portion of the deferred rent that was scheduled to mature within the next twelve months. Effective January 1, 2022, the Company adopted ASC 842 using the modified retrospective approach and utilizing the effective date as its date of initial application. At contract inception, the Company determines whether an arrangement contains a lease based on the unique facts and circumstances present in the arrangement. The lease is assessed for classification as either an operating or finance lease at the lease commencement date, defined as the date on which the leased asset is made available for use by the Company, based on the economic characteristics of the lease. The 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. The Company has elected to take advantage of the short-term lease exemption, which allows for only leases with a term greater than one year to be recognized on the condensed consolidated balance sheets as right-of-use assets, classified as non-current assets, and operating lease liabilities, classified as current and non-current liabilities. Operating lease expense is recognized on a straight-line basis over the lease term. Operating lease liabilities and their corresponding right-of-use assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments, which reflects the fixed rate at which the Company could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. To estimate its incremental borrowing rate, a credit rating applicable to the Company is estimated using a synthetic credit rating analysis since the Company does not currently have a rating agency-based credit rating. In transition to ASC 842, the Company utilized the remaining lease term of its leases in determining the appropriate incremental borrowing rates. Prospectively, the Company will adjust the right-of-use assets for straight-line rent expense or any incentives received and remeasure the lease liability at the net present value using the same incremental borrowing rate that was in effect as of the lease commencement or transition date. Components of a lease are split into three categories: lease components, non-lease components, and non-components. The fixed and in-substance fixed contract consideration (including any consideration related to non-components) are allocated based on the respective relative fair values to the lease components and non-lease components. The Company has elected to account for lease and associated non-lease components together as a single lease component for all underlying assets and allocate all of the contract consideration to the lease component only. Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. The Company assesses its right-of-use assets for impairment in a manner consistent with its assessment for long-lived assets held and used in operations. As a result of the adoption of ASC 842, the Company recorded (i) an operating lease liability of $33.4 million determined using an incremental borrowing rate as of the effective adoption date and (ii) an operating lease right-of-use asset of $33.0 million, net of the unamortized balance of prepaid/accrued rent as of the transition date. There was no impact to the Company’s results of operations and cash flows from operations. ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes (ASU 2019-12), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends certain aspects of the existing guidance to improve consistent application. For EGCs, such as the Company, ASU 2019-12 is effective beginning January 1, 2022, with early adoption permitted. The Company adopted ASU 2019-12 on January 1, 2022. The adoption of this standard did not have a material impact on the Company’s financial position or results of operations upon adoption.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Restrictions on Cash and Cash Equivalents	A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows (in thousands): March 31, 2022 December 31, 2021 Cash and cash equivalents $ 84,640 $ 291,064 Restricted cash 3,950 — Total cash, cash equivalents and restricted cash $ 88,590 $ 291,064

Marketable Securities (Tables)

Marketable Securities (Tables)	3 Months Ended
	Mar. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	The following is a summary of the Company's investment portfolio at March 31, 2022 (in thousands). The Company did not have any marketable securities as of December 31, 2021. Amortized Cost Unrealized Gains Unrealized Losses Fair Value U.S. government agency securities and treasuries $ 95,545 $ — $ 304 $ 95,241 Corporate debt securities 22,882 — 239 22,643 Total securities with a maturity of one year or less $ 118,427 $ — $ 543 $ 117,884 U.S. government agency securities and treasuries 34,684 — 508 34,177 Corporate debt securities 27,686 — 484 27,201 Total securities with a maturity of one to two years $ 62,370 $ — $ 992 $ 61,378 Total available-for-sale securities $ 180,797 $ — $ 1,535 $ 179,262

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of fair value hierarchy for assets and liabilities measured at fair value on recurring basis	The following tables present the Company’s fair value hierarchy for its assets 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 March 31, 2022 Level 1 Level 2 Level 3 Total Cash equivalents $ 84,390 $ — $ — $ 84,390 Marketable securities: U.S. government agency securities and treasuries — 129,418 — 129,418 Corporate bonds — 49,844 — 49,844 Total $ 84,390 $ 179,262 $ — $ 263,652 Fair Value Measurements at December 31, 2021 Level 1 Level 2 Level 3 Total Cash equivalents $ 290,814 $ — $ — $ 290,814 Total $ 290,814 $ — $ — $ 290,814

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
Schedule of Property and equipment, Net	Property and equipment, net consisted of the following at March 31, 2022 and December 31, 2021 (in thousands): March 31, December 31, Laboratory equipment $ 6,773 $ 5,988 Furniture and fixtures 161 96 Computer equipment 43 37 Leasehold improvements 1,556 1,556 Construction in progress 470 — Total property and equipment 9,003 7,677 Less: Accumulated depreciation (1,806) (1,416) Property and equipment, net $ 7,197 $ 6,261

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2022
Accrued Expenses and Other Current Liabilities [Abstract]
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following at March 31, 2022 and December 31, 2021 (in thousands): March 31, December 31, Employee compensation and benefits $ 1,630 $ 4,077 External research and development expenses 1,616 1,032 General and administrative professional service expenses 744 419 Other 534 485 Total accrued expenses and other current liabilities $ 4,524 $ 6,013

Common Stock and Preferred St_2

Common Stock and Preferred Stock (Tables)	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Schedule of Shares Reserved for Future Issuance	The Company has reserved the following shares of common stock for future issuance as of: March 31, 2022 December 31, 2021 Exercise of outstanding stock options 4,412,667 3,461,870 Vesting of outstanding restricted stock 297,754 — Future awards under the 2021 Stock Option and Incentive Plan 2,818,786 2,843,255 Future awards under the 2021 Employee Stock Purchase Plan 591,055 278,762 Total shares of authorized common stock reserved for future issuance 8,120,262 6,583,887

Stock Based Compensation (Table

Stock Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Schedule of Stock-based compensation expense	Stock-based compensation expense recorded in the condensed consolidated statements of operations is as follows (in thousands): Three Months Ended March 31, 2022 2021 Research and development expenses $ 704 $ 56 General and administrative expenses 1,090 108 Total $ 1,794 $ 164
Schedule of assumptions used in the Black-Scholes option-pricing model to determine the fair value of stock options granted	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 during the three months ended March 31, 2022 and 2021: March 31, March 31, Risk‑free interest rate 1.61 % 0.63 % Expected volatility 70 % 76 % Expected dividend yield — — Expected term (in years) 6.06 6.04
Summary of the stock option activity	The following table summarizes the Company’s stock option activity during the three months ended March 31, 2022: Number of Weighted‑ Outstanding as of December 31, 2021 3,461,870 $ 10.38 Granted 999,315 11.67 Exercised (24,891) 2.00 Forfeited (23,627) 10.73 Outstanding as of March 31, 2022 4,412,667 $ 10.72 Exercisable as of March 31, 2022 (1) 2,385,606 $ 6.25 (1) This represents the number of vested and unvested options exercisable as of March 31, 2022.
Summary of unvested restricted stock	A summary of restricted stock activity during the three months ended March 31, 2022 is as follows : Shares Weighted‑ Unvested as of December 31, 2021 — $ — Issued 302,279 11.57 Forfeited (4,525) 11.57 Unvested as of March 31, 2022 297,754 $ 11.57

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Lease, Cost	The components of operating lease cost were as follows (in thousands): Three Months Ended March 31, 2022 Operating lease cost $ 1,890 Variable lease cost — Total lease cost $ 1,890 Supplemental information related to operating leases was as follows: Other information Three Months Ended March 31, 2022 Operating cash flows used for operating leases (in thousands) $ 1,839 Weighted average remaining lease term 3.7 years Weighted average discount rate 3.81%
Lessee, Operating Lease, Liability, Maturity	Future payments due under operating leases as of March 31, 2022 were as follows (in thousands): Maturity of Lease Liability As of March 31, 2022 2022 (excluding the three-months ended March 31, 2022) $ 6,735 2023 9,219 2024 9,494 2025 8,650 Thereafter — Total lease payments $ 34,098 Less: imputed interest (2,242) Present value of operating lease liabilities $ 31,856

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Schedule of basic and diluted net loss per share attributable to common stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended March 31, 2022 2021 Numerator: Net loss attributable to common stockholders $ (21,671) $ (8,380) Denominator: Weighted‑average common shares outstanding, basic and diluted 31,246,916 1,256,487 Net loss per share attributable to common stockholders, basic and diluted $ (0.69) $ (6.67)
Schedule of antidilutive securities excluded from computation of net loss per share	The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended March 31, 2022 2021 Redeemable convertible preferred stock (as converted to common stock) — 19,185,183 Unvested restricted common stock 297,754 7,211 Unvested shares from early exercises 96,532 76,209 Stock options to purchase common stock 4,412,667 1,568,665 4,806,953 20,837,268

Nature of the Business (Details

Nature of the Business (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net loss	$ 21,671	$ 8,380
Accumulated deficit	115,340		$ 93,669
Cash, cash equivalents, and short-term investments	$ 263,900

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Restricted Cash Schedule (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 84,640	$ 291,064
Restricted cash	3,950	0
Total cash, cash equivalents and restricted cash	$ 88,590	$ 291,064	$ 146,186	$ 39,045

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Present value of operating lease liabilities	$ 31,856	$ 33,400
Right-of-use assets, operating leases	$ 31,409	$ 33,000	$ 0

Marketable Securities - Amortiz

Marketable Securities - Amortized Cost (Details) $ in Thousands	Mar. 31, 2022USD ($)
Debt Securities, Current [Abstract]
Amortized Cost	$ 180,797
Unrealized Gains	0
Unrealized Losses	1,535
Total available-for-sale securities	179,262
One Year or Less
Debt Securities, Current [Abstract]
Amortized Cost	118,427
Unrealized Gains	0
Unrealized Losses	543
Total available-for-sale securities	117,884
One Year or Less | U.S. government agency securities and treasuries
Debt Securities, Current [Abstract]
Amortized Cost	95,545
Unrealized Gains	0
Unrealized Losses	304
Total available-for-sale securities	95,241
One Year or Less | Corporate debt securities
Debt Securities, Current [Abstract]
Amortized Cost	22,882
Unrealized Gains	0
Unrealized Losses	239
Total available-for-sale securities	22,643
One to Two Years
Debt Securities, Current [Abstract]
Amortized Cost	62,370
Unrealized Gains	0
Unrealized Losses	992
Total available-for-sale securities	61,378
One to Two Years | U.S. government agency securities and treasuries
Debt Securities, Current [Abstract]
Amortized Cost	34,684
Unrealized Gains	0
Unrealized Losses	508
Total available-for-sale securities	34,177
One to Two Years | Corporate debt securities
Debt Securities, Current [Abstract]
Amortized Cost	27,686
Unrealized Gains	0
Unrealized Losses	484
Total available-for-sale securities	$ 27,201

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) $ in Thousands	Mar. 31, 2022USD ($)security
Investments, Debt and Equity Securities [Abstract]
Number of securities | security	38
Total available-for-sale securities | $	$ 179,262

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	$ 179,262
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	84,390	$ 290,814
Total	263,652	290,814
Fair Value, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	84,390	290,814
Total	84,390	290,814
Fair Value, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Total	179,262	0
Fair Value, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Total	0	$ 0
Fair Value, Recurring | U.S. government agency securities and treasuries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	129,418
Fair Value, Recurring | U.S. government agency securities and treasuries | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0
Fair Value, Recurring | U.S. government agency securities and treasuries | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	129,418
Fair Value, Recurring | U.S. government agency securities and treasuries | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0
Fair Value, Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	49,844
Fair Value, Recurring | Corporate bonds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0
Fair Value, Recurring | Corporate bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	49,844
Fair Value, Recurring | Corporate bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	$ 0

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 9,003		$ 7,677
Less: Accumulated depreciation	(1,806)		(1,416)
Property and equipment, net	7,197		6,261
Depreciation expense	390	$ 199
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,773		5,988
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	161		96
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	43		37
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,556		1,556
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 470		$ 0

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accrued Expenses and Other Current Liabilities [Abstract]
Employee compensation and benefits	$ 1,630	$ 4,077
External research and development expenses	1,616	1,032
General and administrative professional service expenses	744	419
Other	534	485
Total	$ 4,524	$ 6,013

Common Stock and Preferred St_3

Common Stock and Preferred Stock (Details) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Class of Stock
Common stock, shares, authorized (in shares)	150,000,000	150,000,000
Common stock, par value per share (in dollars per share)	$ 0.0001	$ 0.0001
Shares of common stock reserved for issuance (in shares)	8,120,262	6,583,887
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, par or stated value per share (in dollars per share)	$ 0.0001	$ 0.0001
2021 Plan
Class of Stock
Shares of common stock reserved for issuance (in shares)	2,818,786	2,843,255
Stock options to purchase common stock
Class of Stock
Shares of common stock reserved for issuance (in shares)	4,412,667	3,461,870
Restricted Stock
Class of Stock
Shares of common stock reserved for issuance (in shares)	297,754	0
Future awards under the 2021 Employee Stock Purchase Plan
Class of Stock
Shares of common stock reserved for issuance (in shares)	591,055	278,762

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Stock-based compensation
Unvested shares related to early exercises of stock options (in shares)	2,385,606
Vesting of early exercised options (in shares)	96,532		111,756
Unvested early exercises of stock options	$ 0.3		$ 0.3
Stock options to purchase common stock
Stock-based compensation
Weighted-average grant-date fair value of stock options granted (in dollars per share)	$ 7.39	$ 1.61
Unrecognized compensation cost	$ 26.4
Unrecognized compensation cost, weighted-average period for recognition	2 years 2 months 12 days
Restricted Stock
Stock-based compensation
Unrecognized compensation cost	$ 3.4
Unrecognized compensation cost, weighted-average period for recognition	3 years 7 months 6 days
Future awards under the 2021 Employee Stock Purchase Plan
Stock-based compensation
Stock authorized for issuance (in shares)	591,055		278,762
2016 Stock Plan
Stock-based compensation
Stock authorized for issuance (in shares)	2,283,131		2,318,855
2021 Plan
Stock-based compensation
Stock authorized for issuance (in shares)	5,246,076		3,986,270

Stock Based Compensation - Comp

Stock Based Compensation - Compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Stock-based compensation
Share-based compensation expense	$ 1,794	$ 164
Research and development expenses
Stock-based compensation
Share-based compensation expense	704	56
General and administrative expenses
Stock-based compensation
Share-based compensation expense	$ 1,090	$ 108

Stock Based Compensation - Stoc

Stock Based Compensation - Stock Option Valuation (Details) - Stock options to purchase common stock	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Assumptions used to determine the fair value of stock options granted
Risk‑free interest rate	1.61%	0.63%
Expected volatility	70.00%	76.00%
Expected dividend yield	0.00%	0.00%
Expected term (in years)	6 years 21 days	6 years 14 days

Stock Based Compensation - St_2

Stock Based Compensation - Stock option activity (Details)	3 Months Ended
	Mar. 31, 2022$ / sharesshares
Number of Shares
Outstanding at beginning of period (in shares) | shares	3,461,870
Granted (in shares) | shares	999,315
Exercised (in shares) | shares	(24,891)
Forfeited (in shares) | shares	(23,627)
Outstanding at end period (in shares) | shares	4,412,667
Unvested shares related to early exercises of stock options (in shares) | shares	2,385,606
Weighted Average Exercise Price
Weighted-average exercise price outstanding at beginning period (in dollars per share) | $ / shares	$ 10.38
Weighted average exercise price granted (in dollars per share) | $ / shares	11.67
Weighted average exercise price exercised (in dollars per share) | $ / shares	2
Weighted average exercise price forfeited (in dollars per share) | $ / shares	10.73
Weighted average exercise price outstanding at end period (in dollars per share) | $ / shares	10.72
Weighted average exercise price vested and exercisable (in dollars per share) | $ / shares	$ 6.25

Stock Based Compensation - Rest

Stock Based Compensation - Restricted Stock Awards (Details) - Restricted Stock $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)$ / sharesshares
Shares
Unvested balance, at beginning of period (in shares) | shares	0
Issued (in shares) | shares	302,279
Forfeited (in shares) | shares	(4,525)
Unvested balance, at end of period (in shares) | shares	297,754
Weighted- Average Grant -Date Fair Value
Beginning of period (in dollars per share) | $ / shares	$ 0
Issued (in dollars per share) | $ / shares	11.57
Forfeited (in dollars per share) | $ / shares	11.57
End of period (in dollars per share) | $ / shares	$ 11.57
Unrecognized compensation cost | $	$ 3.4
Unrecognized compensation cost, weighted-average period for recognition	3 years 7 months 6 days

Leases - Additional Information

Leases - Additional Information (Details) $ in Millions	Mar. 16, 2022USD ($)sqft$ / sqft	Mar. 31, 2022USD ($)	Jun. 30, 2021sqft	Feb. 29, 2020sqft
Lessee, Lease, Description [Line Items]
Number of square feet | sqft	65,000
Security deposit		$ 0.8
Term of contract	10 years
Lease term	5 years
Fixed monthly rental payments	$ 0.5
Rental expenses annual increase	3.00%
Tenant improvements allowance	$ 19.5
Calculated rentable square foot of premises | $ / sqft	240
Operating leases additional allowance	$ 1.6
Tenant allowance rentable square foot of premises per annum | $ / sqft	20
Interest rate for additional improvements allowance	8.00%
Letters of credit		3.9
Operating lease related expenses prior to commencement		$ 0.6
Massachusetts
Lessee, Lease, Description [Line Items]
Number of square feet | sqft	81,442		8,631	26,235

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Leases [Abstract]
Operating lease cost	$ 1,890
Variable lease cost	0
Total lease cost	$ 1,890

Leases - Cash flow information

Leases - Cash flow information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 1,839
Weighted average remaining lease term	3 years 8 months 12 days
Weighted average discount rate	3.81%

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Jan. 01, 2022
Maturity of Lease Liability
2022 (excluding the three-months ended March 31, 2022)	$ 6,735
2023	9,219
2024	9,494
2025	8,650
Thereafter	0
Total lease payments	34,098
Less: imputed interest	(2,242)
Present value of operating lease liabilities	$ 31,856	$ 33,400

Net Loss per Share - Computatio

Net Loss per Share - Computation of EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Net loss attributable to common stockholders	$ (21,671)	$ (8,380)
Denominator:
Weighted-average common shares outstanding, basic (in shares)	31,246,916	1,256,487
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.69)	$ (6.67)
Numerator:
Net loss attributable to common stockholders	$ (21,671)	$ (8,380)
Denominator:
Weighted-average common shares outstanding, diluted (in shares)	31,246,916	1,256,487
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.69)	$ (6.67)

Net Loss per Share - Antidiluti

Net Loss per Share - Antidilutive securities (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	4,806,953	20,837,268
Redeemable convertible preferred stock (as converted to common stock)
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	0	19,185,183
Unvested restricted common stock
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	297,754	7,211
Unvested shares from early exercises
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	96,532	76,209
Stock options to purchase common stock
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	4,412,667	1,568,665