0001689375-22-000045 | 10-Q | XBRL Viewer

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Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2022	Oct. 31, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 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
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	TRDA
Security Exchange Name	NASDAQ
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
Entity Common Stock, Shares Outstanding (in shares)		31,406,165
Entity Central Index Key	0001689375
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 53,311	$ 291,064
Marketable securities	162,261	0
Prepaid expenses and other current assets	19,161	7,636
Total current assets	234,733	298,700
Property and equipment, net	7,444	6,261
Restricted cash	3,950	0
Right-of-use assets, operating leases	27,382
Other non-current assets	954	872
Total assets	274,463	305,833
Current liabilities:
Accounts payable	1,341	706
Accrued expenses and other current liabilities	11,951	6,013
Operating lease obligations, current portion	8,259
Total current liabilities	21,551	6,719
Operating lease obligations, non-current	19,692
Deferred rent, net of current portion		396
Total liabilities	41,243	7,115
Commitments and contingencies (Note 10)
Stockholders’ equity:
Common stock, par value $0.0001; 150,000,000 shares authorized; 31,393,110 shares issued and 31,325,373 shares outstanding as of September 30, 2022 and 31,336,092 shares issued and 31,224,336 shares outstanding as of December 31, 2021	3	3
Additional paid‑in capital	399,620	392,384
Accumulated other comprehensive loss	(2,747)	0
Accumulated deficit	(163,656)	(93,669)
Total stockholders’ equity	233,220	298,718
Total liabilities and stockholders’ equity	$ 274,463	$ 305,833

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 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)	31,393,110	31,336,092
Common stock, shares, outstanding (in shares)	31,325,373	31,224,336

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating expenses:
Research and development	$ 18,958	$ 10,513	$ 50,924	$ 23,564
General and administrative	6,978	3,851	20,745	9,103
Total operating expenses	25,936	14,364	71,669	32,667
Loss from operations	(25,936)	(14,364)	(71,669)	(32,667)
Other income (expense):
Interest and other income (expense), net	799	(66)	1,682	(44)
Total other income (expense), net	799	(66)	1,682	(44)
Net loss	$ (25,137)	$ (14,430)	$ (69,987)	$ (32,711)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.80)	$ (9.78)	$ (2.24)	$ (24.18)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.80)	$ (9.78)	$ (2.24)	$ (24.18)
Weighted-average common shares outstanding, basic (in shares)	31,298,052	1,475,170	31,273,612	1,352,721
Weighted-average common shares outstanding, diluted (in shares)	31,298,052	1,475,170	31,273,612	1,352,721
Other comprehensive loss:
Unrealized loss on marketable securities	$ (482)	$ 0	$ (2,747)	$ 0
Total other comprehensive loss	(482)	0	(2,747)	0
Total comprehensive loss	$ (25,619)	$ (14,430)	$ (72,734)	$ (32,711)

CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	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
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of redeemable convertible preferred stock, net of issuance costs (in shares)	53,522,099
Issuance of Series B redeemable convertible preferred stock, net of issuance costs of $420	$ 115,831
Ending Balances (in shares) at Mar. 31, 2021	138,821,984
Ending Balances at Mar. 31, 2021	$ 197,489
Beginning Balances (in shares) at Dec. 31, 2020		1,244,139
Beginning Balances at Dec. 31, 2020	(41,490)	$ 0	$ 1,021	$ 0	$ (42,511)
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		29
Vesting of restricted common stock (in shares)		4,326
Vesting of early exercised options (in shares)		6,529
Vesting of early exercised options	8		8
Stock‑based compensation	164		164
Net loss	(8,380)				(8,380)
Ending Balances (in shares) at Mar. 31, 2021		1,271,447
Ending Balances at Mar. 31, 2021	$ (49,669)	$ 0	1,222	0	(50,891)
Beginning Balances (in shares) at Dec. 31, 2020	85,299,885
Beginning Balances at Dec. 31, 2020	$ 81,658
Ending Balances (in shares) at Sep. 30, 2021	138,821,984
Ending Balances at Sep. 30, 2021	$ 197,489
Beginning Balances (in shares) at Dec. 31, 2020		1,244,139
Beginning Balances at Dec. 31, 2020	(41,490)	$ 0	1,021	0	(42,511)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss	0
Net loss	(32,711)
Ending Balances (in shares) at Sep. 30, 2021		1,547,774
Ending Balances at Sep. 30, 2021	$ (72,591)	$ 0	2,631	0	(75,222)
Beginning Balances (in shares) at Mar. 31, 2021	138,821,984
Beginning Balances at Mar. 31, 2021	$ 197,489
Ending Balances (in shares) at Jun. 30, 2021	138,821,984
Ending Balances at Jun. 30, 2021	$ 197,489
Beginning Balances (in shares) at Mar. 31, 2021		1,271,447
Beginning Balances at Mar. 31, 2021	(49,669)	$ 0	1,222	0	(50,891)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		119,359
Issuance of common stock upon exercise of stock options	212		212
Vesting of restricted common stock (in shares)		4,327
Vesting of early exercised options (in shares)		10,592
Vesting of early exercised options	18		18
Stock‑based compensation	326		326
Net loss	(9,901)				(9,901)
Ending Balances (in shares) at Jun. 30, 2021		1,405,725
Ending Balances at Jun. 30, 2021	$ (59,014)	$ 0	1,778	0	(60,792)
Ending Balances (in shares) at Sep. 30, 2021	138,821,984
Ending Balances at Sep. 30, 2021	$ 197,489
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		57,661
Issuance of common stock upon exercise of stock options	106		106
Vesting of restricted common stock (in shares)		2,884
Vesting of early exercised options (in shares)		81,504
Vesting of early exercised options	170		170
Stock‑based compensation	577		577
Other comprehensive loss	0
Net loss	(14,430)				(14,430)
Ending Balances (in shares) at Sep. 30, 2021		1,547,774
Ending Balances at Sep. 30, 2021	$ (72,591)	$ 0	2,631	0	(75,222)
Beginning Balances (in shares) at Dec. 31, 2021	0
Beginning Balances at Dec. 31, 2021	$ 0
Ending Balances (in shares) at Mar. 31, 2022	0
Ending Balances at Mar. 31, 2022	$ 0
Beginning Balances (in shares) at Dec. 31, 2021	31,224,336	31,224,336
Beginning Balances at Dec. 31, 2021	$ 298,718	$ 3	392,384	0	(93,669)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		24,891
Issuance of common stock upon exercise of stock options	50		50
Vesting of early exercised options (in shares)		15,224
Vesting of early exercised options	35		35
Stock‑based compensation	1,794		1,794
Other comprehensive loss	(1,535)			(1,535)
Net loss	(21,671)				(21,671)
Ending Balances (in shares) at Mar. 31, 2022		31,264,451
Ending Balances at Mar. 31, 2022	$ 277,391	$ 3	394,263	(1,535)	(115,340)
Beginning Balances (in shares) at Dec. 31, 2021	0
Beginning Balances at Dec. 31, 2021	$ 0
Ending Balances (in shares) at Sep. 30, 2022	0
Ending Balances at Sep. 30, 2022	$ 0
Beginning Balances (in shares) at Dec. 31, 2021	31,224,336	31,224,336
Beginning Balances at Dec. 31, 2021	$ 298,718	$ 3	392,384	0	(93,669)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	57,018
Other comprehensive loss	$ (2,747)
Net loss	$ (69,987)
Ending Balances (in shares) at Sep. 30, 2022	31,325,373	31,325,373
Ending Balances at Sep. 30, 2022	$ 233,220	$ 3	399,620	(2,747)	(163,656)
Beginning Balances (in shares) at Mar. 31, 2022	0
Beginning Balances at Mar. 31, 2022	$ 0
Ending Balances (in shares) at Jun. 30, 2022	0
Ending Balances at Jun. 30, 2022	$ 0
Beginning Balances (in shares) at Mar. 31, 2022		31,264,451
Beginning Balances at Mar. 31, 2022	277,391	$ 3	394,263	(1,535)	(115,340)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		5,259
Issuance of common stock upon exercise of stock options	11		11
Vesting of early exercised options (in shares)		14,738
Vesting of early exercised options	34		34
Stock‑based compensation	2,512		2,512
Other comprehensive loss	(730)			(730)
Net loss	(23,179)				(23,179)
Ending Balances (in shares) at Jun. 30, 2022		31,284,448
Ending Balances at Jun. 30, 2022	$ 256,039	$ 3	396,820	(2,265)	(138,519)
Ending Balances (in shares) at Sep. 30, 2022	0
Ending Balances at Sep. 30, 2022	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		26,868
Issuance of common stock upon exercise of stock options	60		60
Vesting of early exercised options (in shares)		14,057
Vesting of early exercised options	33		33
Stock‑based compensation	2,707		2,707
Other comprehensive loss	(482)			(482)
Net loss	$ (25,137)				(25,137)
Ending Balances (in shares) at Sep. 30, 2022	31,325,373	31,325,373
Ending Balances at Sep. 30, 2022	$ 233,220	$ 3	$ 399,620	$ (2,747)	$ (163,656)

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net loss	$ (69,987)	$ (32,711)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	1,370	753
Stock‑based compensation expense	7,013	1,068
Amortization of premiums and discounts on marketable securities, net	255	0
(Gain) loss on disposal of property and equipment	(1)	153
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(12,020)	(449)
Right-of-use assets, operating leases	5,609
Other non-current assets	(82)	(1,923)
Accounts payable	694	311
Accrued expenses and other current liabilities	6,104	2,138
Operating lease liabilities	(5,437)
Deferred rent		339
Net cash used in operating activities	(66,482)	(30,321)
Cash flows from investing activities:
Purchases of property and equipment	(2,179)	(3,258)
Purchases of marketable securities	(221,977)	0
Maturities of marketable securities	56,714	0
Net cash used in investing activities	(167,442)	(3,258)
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	115,831
Proceeds from exercise of stock options	121	347
Proceeds from the early exercise of stock options	0	528
Net cash provided by financing activities	121	116,706
Net increase (decrease) in cash, cash equivalents, and restricted cash	(233,803)	83,127
Cash, cash equivalents, and restricted cash at beginning of period	291,064	39,045
Cash, cash equivalents, and restricted cash at end of period	57,261	122,172
Supplemental cash flow disclosures:
Deferred financing costs in accounts payable and accrued expenses	0	505
Purchases of property and equipment included in accounts payable and accrued expenses	32	832
Right-of-use assets obtained in exchange for operating lease liabilities	32,991
Transfer of deposits for equipment from operating to investing cash flows	495	0
Vesting of options early exercised subject to repurchase	$ 102	$ 195

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

Nature of the Business	9 Months Ended
Nature of the Business	Sep. 30, 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 (EEVTM) therapeutics as a new class of medicines and 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 $70.0 million and $32.7 million for the nine months ended September 30, 2022 and 2021, respectively. As of September 30, 2022, the Company had an accumulated deficit of $163.7 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 $215.6 million as of September 30, 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 Accounting Policies

9 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

The significant accounting policies used in preparation of these condensed consolidated financial statements as of and for the three and nine months ended September 30, 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 September 30, 2022, and results of operations for the interim periods ended September 30, 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.

Cash, Cash Equivalents, and Restricted Cash

The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. At September 30, 2022 and December 31, 2021, cash and cash equivalents include standard checking accounts and money market account funds that invest primarily in U.S. government-backed securities and treasuries. At September 30, 2022, cash equivalents also includes debt securities classified as cash equivalents.

As of September 30, 2022, 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. As of December 31, 2021, the Company had no restricted cash. A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows (in thousands):


	September 30, 2022		December 31, 2021
Cash and cash equivalents	$	53,311	$	291,064
Restricted cash	3,950		—
Total cash, cash equivalents and restricted cash	$	57,261	$	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 and nine months ended September 30, 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 and nine months ended September 30, 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 other than changes to include the presentation of changes in the right-of-use asset and lease liability in the statement of cash flows.

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

9 Months Ended

Sep. 30, 2022

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

The following is a summary of the Company's marketable securities at September 30, 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	$	103,011	$	—	$	1,264	$	101,747
Corporate debt securities	34,956		—		622		34,334
Total securities with a maturity of one year or less	$	137,967	$	—	$	1,886	$	136,081

U.S. government agency securities and treasuries	11,790		—		263		11,527
Corporate debt securities	15,251		—		598		14,653
Total securities with a maturity of one to two years	$	27,041	$	—	$	861	$	26,180
Total available-for-sale securities	$	165,008	$	—	$	2,747	$	162,261

As of September 30, 2022, the Company had 36 marketable securities with a total fair market value of $162.3 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 and nine months ended September 30, 2022.

The summary above excludes $9.0 million of debt securities classified as cash equivalents. For all debt securities classified as cash equivalents, amortized cost approximated fair value.

Fair Value Measurements

9 Months Ended

Sep. 30, 2022

Fair Value Disclosures [Abstract]

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 September 30, 2022
	Level 1		Level 2		Level 3		Total
Cash equivalents: (1)
Money market funds	$	44,074	$	—	$	—	$	44,074
U.S. government agency securities and treasuries	—		8,987		—		8,987
Marketable securities:
U.S. government agency securities and treasuries	—		113,274		—		113,274
Corporate bonds	—		48,987		—		48,987
Total	$	44,074	$	171,248	$	—	$	215,322


	Fair Value Measurements at December 31, 2021
	Level 1		Level 2		Level 3		Total
Cash equivalents: (1)
Money market funds	$	290,814	$	—	$	—	$	290,814
Total	$	290,814	$	—	$	—	$	290,814

(1)The cash equivalent amounts above do not include $0.3 million of cash related to checking accounts included in cash and cash equivalents as of September 30, 2022 and December 31, 2021. These amounts are excluded as no valuation is needed for cash in checking accounts.

Money market funds are classified within Level 1 of the fair value hierarchy because they are valued using quoted market prices in active markets. The Company measures its debt securities at fair value on a recurring basis using inputs that are observable or can be corroborated by observable market data and classifies those instruments within Level 2 of the fair value hierarchy.

- Definition

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

+ References + Details

Property and Equipment, Net

9 Months Ended

Sep. 30, 2022

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment, net consisted of the following at September 30, 2022 and December 31, 2021 (in thousands):


	September 30, 2022		December 31, 2021
Laboratory equipment	$	7,939	$	5,988
Furniture and fixtures	161		96
Computer equipment	43		37
Leasehold improvements	2,026		1,556
Construction in progress	51		—
Total property and equipment	10,220		7,677
Less: Accumulated depreciation	(2,776)		(1,416)
Property and equipment, net	$	7,444	$	6,261

Depreciation expense for the three months ended September 30, 2022 and 2021 was $0.5 million and $0.3 million, respectively. Depreciation expense for the nine months ended September 30, 2022 and 2021 was $1.4 million and $0.8 million, respectively.

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2022

Accrued Expenses and Other Current Liabilities [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following at September 30, 2022 and December 31, 2021 (in thousands):


	September 30, 2022		December 31, 2021
Employee compensation and benefits	$	4,033	$	4,077
External research and development expenses	2,620		1,032
General and administrative professional service expenses	563		419
Tenant Improvement Costs	4,494		—
Other	241		485
Total accrued expenses and other current liabilities	$	11,951	$	6,013

The accrued tenant improvement costs in the table above relate to the lease agreement between the Company and IDB 17-19 Drydock Limited Partnership as further discussed in Note 11 Leases.

Common Stock and Preferred Stock

9 Months Ended

Sep. 30, 2022

Equity [Abstract]

Common Stock and Preferred Stock

Common Stock

As of September 30, 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:


	September 30, 2022	December 31, 2021
Exercise of outstanding stock options	5,002,730	3,461,870
Vesting of outstanding restricted stock	445,445	—
Future awards under the 2021 Stock Option and Incentive Plan	2,048,905	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	8,088,135	6,583,887

Preferred Stock

As of September 30, 2022 and December 31, 2021, the Company was authorized to issue 10,000,000 shares of undesignated preferred stock, par value $0.0001 per share, in one or more series and to fix the rights, preferences, privileges and restrictions thereof. As of September 30, 2022 and December 31, 2021, there were no shares of undesignated preferred stock issued or outstanding.

- Definition

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 13
-Subparagraph (b)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stock-Based Compensation

9 Months Ended

Sep. 30, 2022

Share-based Payment Arrangement [Abstract]

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 5,255,443 as of September 30, 2022 primarily 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 September 30, 2022 due to the automatic annual

increase provision within the 2021 ESPP. The first offering period commenced on July 1, 2022 and will end on December 15, 2022.

2016 Plan

The total shares of common stock authorized for issuance under the 2016 Plan as of September 30, 2022 and December 31, 2021 were 2,241,637 shares and 2,318,855 shares, respectively.

Stock-Based Compensation

Stock-based compensation expense recorded in the condensed consolidated statements of operations and comprehensive loss is as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Research and development expenses	$	1,158	$	182	$	2,836	$	344
General and administrative expenses	1,549		396		4,177		724
Total	$	2,707	$	578	$	7,013	$	1,068

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 nine months ended September 30, 2022 and 2021:


	September 30, 2022		September 30, 2021
Risk‑free interest rate	2.11	%	0.99	%
Expected volatility	71	%	74	%
Expected dividend yield	—		—
Expected term (in years)	6.04		6.02

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 67,737 and 111,756 unvested shares related to early exercises of stock options as of September 30, 2022 and December 31, 2021, respectively. As of September 30, 2022 and December 31, 2021, the liability associated with the unvested early exercise of stock options was $0.2 million and $0.3 million, respectively.

Stock Options

The following table summarizes the Company’s stock option activity during the nine months ended September 30, 2022:


	Number of Shares	Weighted‑ Average Exercise Price

Outstanding as of December 31, 2021	3,461,870	$	10.38
Granted	1,660,987	11.34
Exercised	(57,018)	2.12
Forfeited	(63,109)	11.83
Outstanding as of September 30, 2022	5,002,730	$	10.77
Exercisable as of September 30, 2022 (1)	2,506,844	$	7.16

(1)This represents the number of vested and unvested options exercisable as of September 30, 2022.

The weighted-average grant-date fair value of stock options granted during the nine months ended September 30, 2022 and 2021 was $7.26 per share and $6.02 per share, respectively. As of September 30, 2022, there was $26.2 million of unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted-average period of 3.02 years.

Restricted Stock Units

During the nine months ended September 30, 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 nine months ended September 30, 2022 is as follows:


	Shares	Weighted‑ Average Grant‑Date Fair Value
Unvested as of December 31, 2021	—	$	—
Issued	456,845	12.05
Forfeited	(11,400)	11.62
Unvested as of September 30, 2022	445,445	$	12.06

As of September 30, 2022, there was $4.7 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 3.49 years.

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 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.

- Definition

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

+ References

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

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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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+ Details

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesThe 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 material changes to its commitments except those discussed in Note 11 Leases.

Leases

9 Months Ended

Sep. 30, 2022

Leases [Abstract]

Leases

The Company’s operating lease activity is comprised of non-cancelable facility leases for office and laboratory space in Boston, Massachusetts. The Company entered into an operating lease for office and laboratory space in Boston, Massachusetts in February 2020, and entered into subsequent amendments in 2021. The amendments run co-terminus with the existing lease. The Company has a total of 42,046 square feet licensed at this facility. The Company has the option to terminate the lease and amendments after November 30, 2023 without penalty. At the adoption of ASC 842, the Company concluded that it is not reasonably certain that it will exercise this option to terminate the lease early. 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 September 30, 2022		Nine Months Ended September 30, 2022
Operating lease cost	$	2,294	$	6,479
Variable lease cost	—		—
Total lease cost	$	2,294	$	6,479

Supplemental information related to operating leases was as follows:


Other information	Nine Months Ended September 30, 2022
Operating cash flows used for operating leases (in thousands)	$	6,306
Weighted average remaining lease term	3.2 years
Weighted average discount rate	3.81%

Future payments due under operating leases as of September 30, 2022 were as follows (in thousands):


Maturity of Lease Liability	As of September 30, 2022
2022 (excluding the nine-months ended September 30, 2022)	$	2,268
2023	9,219
2024	9,494
2025	8,650
Thereafter	—
Total lease payments	$	29,631
Less: imputed interest	(1,680)
Present value of operating lease liabilities	$	27,951

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 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. The Company has (i) the option to extend the IDB Lease 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 for use in its regular operations, or (ii) 10 months following the Commencement Date, provided that in the event the Landlord’s build-out of the Premises is not complete on such date, base rent becomes due upon substantial completion of such 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 tenant improvements for the Premises. 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 tenant 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 cash-collateralized letter of credit, which may be reduced in the future subject to reduction requirements specified in the IDB Lease therein. The cash collateralizing the letter of credit is classified as restricted cash on the Company's condensed consolidated balance sheets.

The Company concluded that the improvements resulting from both the Landlord's build-out and the tenant improvements are the Landlord's assets for accounting purposes. Costs incurred by the Company related to the tenant improvements up to the Landlord's allowance are pass-through costs and will be reimbursed. Costs incurred by the Company related to the tenant improvements in excess of the Landlord's allowance will be treated as prepaid rent and will increase the right-of-use asset once the accounting commencement date occurs. As of September 30, 2022, the Company has incurred $13.7 million related to the build out of the lease space prior to the commencement date. The amount is included in other current assets as the Company expects to receive reimbursement for such costs in the next 12 months. The accounting commencement date, which has not occurred as of September 30, 2022, will occur when both the Landlord's build-out and the tenant improvements are substantially complete. The Company will assess the classification of the IDB Lease at the accounting commencement date and measure the right-of-use asset and lease liability. As the accounting commencement date had not occurred as of September 30, 2022, the IDB Lease is excluded from the table above.

Net Loss per Share

9 Months Ended

Sep. 30, 2022

Earnings Per Share [Abstract]

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 September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Numerator:
Net loss attributable to common stockholders	$	(25,137)	$	(14,430)	$	(69,987)	$	(32,711)
Denominator:
Weighted‑average common shares outstanding, basic and diluted	31,298,052		1,475,170		31,273,612		1,352,721
Net loss per share attributable to common stockholders, basic and diluted	$	(0.80)	$	(9.78)	$	(2.24)	$	(24.18)

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:


	Nine Months Ended September 30,
	2022	2021
Redeemable convertible preferred stock (as converted to common stock)	—	19,185,183
Unvested restricted common stock	445,445	—
Unvested shares from early exercises	67,737	136,520
Stock options to purchase common stock	5,002,730	2,369,563
	5,515,912	21,691,266

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 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 Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 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 September 30, 2022, and results of operations for the interim periods ended September 30, 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.
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. At September 30, 2022 and December 31, 2021, cash and cash equivalents include standard checking accounts and money market account funds that invest primarily in U.S. government-backed securities and treasuries. At September 30, 2022, cash equivalents also includes debt securities classified as cash equivalents. As of September 30, 2022, 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. As of December 31, 2021, the Company had no restricted cash.
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 LossComprehensive loss includes net loss and other comprehensive income (loss).
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 other than changes to include the presentation of changes in the right-of-use asset and lease liability in the statement of cash flows. 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 Accounting Policies (Tables)

9 Months Ended

Sep. 30, 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):


	September 30, 2022		December 31, 2021
Cash and cash equivalents	$	53,311	$	291,064
Restricted cash	3,950		—
Total cash, cash equivalents and restricted cash	$	57,261	$	291,064

Schedule of Cash and Cash Equivalents


	September 30, 2022		December 31, 2021
Cash and cash equivalents	$	53,311	$	291,064
Restricted cash	3,950		—
Total cash, cash equivalents and restricted cash	$	57,261	$	291,064

Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2022

Investments, Debt and Equity Securities [Abstract]

Debt Securities, Available-for-sale

The following is a summary of the Company's marketable securities at September 30, 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	$	103,011	$	—	$	1,264	$	101,747
Corporate debt securities	34,956		—		622		34,334
Total securities with a maturity of one year or less	$	137,967	$	—	$	1,886	$	136,081

U.S. government agency securities and treasuries	11,790		—		263		11,527
Corporate debt securities	15,251		—		598		14,653
Total securities with a maturity of one to two years	$	27,041	$	—	$	861	$	26,180
Total available-for-sale securities	$	165,008	$	—	$	2,747	$	162,261

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2022

Fair Value Disclosures [Abstract]

Schedule of fair value hierarchy for assets and liabilities measured at fair value on recurring basis


	Fair Value Measurements at September 30, 2022
	Level 1		Level 2		Level 3		Total
Cash equivalents: (1)
Money market funds	$	44,074	$	—	$	—	$	44,074
U.S. government agency securities and treasuries	—		8,987		—		8,987
Marketable securities:
U.S. government agency securities and treasuries	—		113,274		—		113,274
Corporate bonds	—		48,987		—		48,987
Total	$	44,074	$	171,248	$	—	$	215,322


	Fair Value Measurements at December 31, 2021
	Level 1		Level 2		Level 3		Total
Cash equivalents: (1)
Money market funds	$	290,814	$	—	$	—	$	290,814
Total	$	290,814	$	—	$	—	$	290,814

Property and Equipment, Net (Tables)

9 Months Ended

Sep. 30, 2022

Property, Plant and Equipment [Abstract]

Schedule of Property and equipment, Net

Property and equipment, net consisted of the following at September 30, 2022 and December 31, 2021 (in thousands):


	September 30, 2022		December 31, 2021
Laboratory equipment	$	7,939	$	5,988
Furniture and fixtures	161		96
Computer equipment	43		37
Leasehold improvements	2,026		1,556
Construction in progress	51		—
Total property and equipment	10,220		7,677
Less: Accumulated depreciation	(2,776)		(1,416)
Property and equipment, net	$	7,444	$	6,261

Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 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 September 30, 2022 and December 31, 2021 (in thousands):


	September 30, 2022		December 31, 2021
Employee compensation and benefits	$	4,033	$	4,077
External research and development expenses	2,620		1,032
General and administrative professional service expenses	563		419
Tenant Improvement Costs	4,494		—
Other	241		485
Total accrued expenses and other current liabilities	$	11,951	$	6,013

Common Stock and Preferred Stock (Tables)

9 Months Ended

Sep. 30, 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:


	September 30, 2022	December 31, 2021
Exercise of outstanding stock options	5,002,730	3,461,870
Vesting of outstanding restricted stock	445,445	—
Future awards under the 2021 Stock Option and Incentive Plan	2,048,905	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	8,088,135	6,583,887

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2022

Share-based Payment Arrangement [Abstract]

Schedule of Stock-based compensation expense

Stock-based compensation expense recorded in the condensed consolidated statements of operations and comprehensive loss is as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Research and development expenses	$	1,158	$	182	$	2,836	$	344
General and administrative expenses	1,549		396		4,177		724
Total	$	2,707	$	578	$	7,013	$	1,068

Schedule of assumptions used in the Black-Scholes option-pricing model to determine the fair value of stock options granted


	September 30, 2022		September 30, 2021
Risk‑free interest rate	2.11	%	0.99	%
Expected volatility	71	%	74	%
Expected dividend yield	—		—
Expected term (in years)	6.04		6.02

Summary of the stock option activity

The following table summarizes the Company’s stock option activity during the nine months ended September 30, 2022:


	Number of Shares	Weighted‑ Average Exercise Price

Outstanding as of December 31, 2021	3,461,870	$	10.38
Granted	1,660,987	11.34
Exercised	(57,018)	2.12
Forfeited	(63,109)	11.83
Outstanding as of September 30, 2022	5,002,730	$	10.77
Exercisable as of September 30, 2022 (1)	2,506,844	$	7.16

(1)This represents the number of vested and unvested options exercisable as of September 30, 2022.

Summary of unvested restricted stock

A summary of restricted stock activity during the nine months ended September 30, 2022 is as follows:


	Shares	Weighted‑ Average Grant‑Date Fair Value
Unvested as of December 31, 2021	—	$	—
Issued	456,845	12.05
Forfeited	(11,400)	11.62
Unvested as of September 30, 2022	445,445	$	12.06

Leases (Tables)

9 Months Ended

Sep. 30, 2022

Leases [Abstract]

Lease, Cost

The components of operating lease cost were as follows (in thousands):


	Three Months Ended September 30, 2022		Nine Months Ended September 30, 2022
Operating lease cost	$	2,294	$	6,479
Variable lease cost	—		—
Total lease cost	$	2,294	$	6,479

Supplemental information related to operating leases was as follows:


Other information	Nine Months Ended September 30, 2022
Operating cash flows used for operating leases (in thousands)	$	6,306
Weighted average remaining lease term	3.2 years
Weighted average discount rate	3.81%

Lessee, Operating Lease, Liability, Maturity

Future payments due under operating leases as of September 30, 2022 were as follows (in thousands):


Maturity of Lease Liability	As of September 30, 2022
2022 (excluding the nine-months ended September 30, 2022)	$	2,268
2023	9,219
2024	9,494
2025	8,650
Thereafter	—
Total lease payments	$	29,631
Less: imputed interest	(1,680)
Present value of operating lease liabilities	$	27,951

Net Loss per Share (Tables)

9 Months Ended

Sep. 30, 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 September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Numerator:
Net loss attributable to common stockholders	$	(25,137)	$	(14,430)	$	(69,987)	$	(32,711)
Denominator:
Weighted‑average common shares outstanding, basic and diluted	31,298,052		1,475,170		31,273,612		1,352,721
Net loss per share attributable to common stockholders, basic and diluted	$	(0.80)	$	(9.78)	$	(2.24)	$	(24.18)

Schedule of antidilutive securities excluded from computation of net loss per share


	Nine Months Ended September 30,
	2022	2021
Redeemable convertible preferred stock (as converted to common stock)	—	19,185,183
Unvested restricted common stock	445,445	—
Unvested shares from early exercises	67,737	136,520
Stock options to purchase common stock	5,002,730	2,369,563
	5,515,912	21,691,266

Nature of the Business (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Nature of the Business (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net loss attributable to common stockholders	$ 25,137	$ 23,179	$ 21,671	$ 14,430	$ 9,901	$ 8,380	$ 69,987	$ 32,711
Accumulated deficit	163,656						163,656		$ 93,669
Cash, cash equivalents, and short-term investments	$ 215,600						$ 215,600

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

+ References + Details

Summary of Significant Accounting Policies - Restricted Cash Schedule (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 53,311	$ 291,064
Restricted cash	3,950	0
Total cash, cash equivalents and restricted cash	$ 57,261	$ 291,064	$ 122,172	$ 39,045

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Jan. 01, 2022
Lessee, Lease, Description [Line Items]
Operating lease liability	$ 27,951
Right-of-use assets, operating leases	$ 27,382
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease liability		$ 33,400
Right-of-use assets, operating leases		$ 33,000

Marketable Securities - Amortized Cost (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Debt Securities, Current [Abstract]
Debt securities, available-for-sale, year one	$ 137,967
Debt securities, available-for-sale, one to two years	27,041
Total available-for-sale securities	165,008
Debt securities, available-for-sale, fair value, year one	136,081
Debt securities, available-for-sale, fair value, one to two years	26,180
Total available-for-sale securities	162,261
U.S. government agency securities and treasuries
Debt Securities, Current [Abstract]
Debt securities, available-for-sale, year one	103,011
Debt securities, available-for-sale, one to two years	11,790
Debt securities, available-for-sale, fair value, year one	101,747
Debt securities, available-for-sale, fair value, one to two years	11,527
U.S. government agency securities and treasuries \| One Year or Less
Debt Securities, Current [Abstract]
Unrealized Gains	0
Unrealized Losses	1,264
U.S. government agency securities and treasuries \| One to Two Years
Debt Securities, Current [Abstract]
Unrealized Gains	0
Unrealized Losses	263
Corporate debt securities
Debt Securities, Current [Abstract]
Debt securities, available-for-sale, year one	34,956
Debt securities, available-for-sale, one to two years	15,251
Debt securities, available-for-sale, fair value, year one	34,334
Debt securities, available-for-sale, fair value, one to two years	14,653
Corporate debt securities \| One Year or Less
Debt Securities, Current [Abstract]
Unrealized Gains	0
Unrealized Losses	622
Corporate debt securities \| One to Two Years
Debt Securities, Current [Abstract]
Unrealized Gains	0
Unrealized Losses	598
Debt securities, current maturity \| One Year or Less
Debt Securities, Current [Abstract]
Unrealized Gains	0
Unrealized Losses	1,886
Debt securities, non current maturity \| One to Two Years
Debt Securities, Current [Abstract]
Unrealized Gains	0
Unrealized Losses	861
Available-for-sale Securities
Debt Securities, Current [Abstract]
Unrealized Gains	0
Unrealized Losses	$ 2,747

Marketable Securities - Additional Information (Details) $ in Thousands	Sep. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Number of securities \| security	36
Market value of marketable securities	$ 162,300
Fair Value, Recurring
Schedule of Held-to-maturity Securities [Line Items]
Cash equivalents	44,074	$ 290,814
Level 2 \| Fair Value, Recurring
Schedule of Held-to-maturity Securities [Line Items]
Cash equivalents	0	$ 0
U.S. government agency securities and treasuries \| Fair Value, Recurring
Schedule of Held-to-maturity Securities [Line Items]
Cash equivalents	8,987
U.S. government agency securities and treasuries \| Level 2 \| Fair Value, Recurring
Schedule of Held-to-maturity Securities [Line Items]
Cash equivalents	$ 8,987

Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	$ 162,261
Cash	300	$ 300
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	44,074	290,814
Total	215,322	290,814
Fair Value, Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	44,074	290,814
Total	44,074	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	171,248	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]
Cash equivalents	8,987
Total available-for-sale securities	113,274
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]
Cash equivalents	0
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]
Cash equivalents	8,987
Total available-for-sale securities	113,274
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]
Cash equivalents	0
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	48,987
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	48,987
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 (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 10,220		$ 10,220		$ 7,677
Less: Accumulated depreciation	(2,776)		(2,776)		(1,416)
Property and equipment, net	7,444		7,444		6,261
Depreciation expense	500	$ 300	1,370	$ 753
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	7,939		7,939		5,988
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	161		161		96
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	43		43		37
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,026		2,026		1,556
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 51		$ 51		$ 0

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accrued Expenses and Other Current Liabilities [Abstract]
Employee compensation and benefits	$ 4,033	$ 4,077
External research and development expenses	2,620	1,032
General and administrative professional service expenses	563	419
Tenant Improvement Costs	4,494	0
Other	241	485
Total accrued expenses and other current liabilities	$ 11,951	$ 6,013

Common Stock and Preferred Stock (Details) - $ / shares	Sep. 30, 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)	8,088,135	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)	2,048,905	2,843,255
Stock options to purchase common stock
Class of Stock
Shares of common stock reserved for issuance (in shares)	5,002,730	3,461,870
Restricted Stock
Class of Stock
Shares of common stock reserved for issuance (in shares)	445,445	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 - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Stock-based compensation
Unvested shares from early exercises (in shares)	67,737		111,756
Unvested early exercises of stock options	$ 0.2		$ 0.3
Future awards under the 2021 Employee Stock Purchase Plan
Stock-based compensation
Stock authorized for issuance (in shares)	591,055		278,762
Stock options to purchase common stock
Stock-based compensation
Weighted-average grant-date fair value of stock options granted (in dollars per share)	$ 7.26	$ 6.02
Unrecognized compensation cost	$ 26.2
Unrecognized compensation cost, weighted-average period for recognition	3 years 7 days
Restricted Stock
Stock-based compensation
Unrecognized compensation cost	$ 4.7
Unrecognized compensation cost, weighted-average period for recognition	3 years 5 months 26 days
2021 Plan
Stock-based compensation
Stock authorized for issuance (in shares)	5,255,443		3,986,270
2016 Stock Plan
Stock-based compensation
Stock authorized for issuance (in shares)	2,241,637		2,318,855

Stock-Based Compensation - Compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Stock-based compensation
Share-based compensation expense	$ 2,707	$ 578	$ 7,013	$ 1,068
Research and development expenses
Stock-based compensation
Share-based compensation expense	1,158	182	2,836	344
General and administrative expenses
Stock-based compensation
Share-based compensation expense	$ 1,549	$ 396	$ 4,177	$ 724

Stock-Based Compensation - Stock Option Valuation (Details) - Stock options to purchase common stock	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Assumptions used to determine the fair value of stock options granted
Risk‑free interest rate	2.11%	0.99%
Expected volatility	71.00%	74.00%
Expected dividend yield	0.00%	0.00%
Expected term (in years)	6 years 14 days	6 years 7 days

Stock-Based Compensation - Stock option activity (Details) - $ / shares	9 Months Ended
	Sep. 30, 2022
Number of Shares
Outstanding at beginning of period (in shares)	3,461,870
Granted (in shares)	1,660,987
Exercised (in shares)	(57,018)
Forfeited (in shares)	(63,109)
Outstanding at end period (in shares)	5,002,730
Exercisable (in shares)	2,506,844
Weighted Average Exercise Price
Outstanding at beginning period (in dollars per share)	$ 10.38
Granted (in dollars per share)	11.34
Exercised (in dollars per share)	2.12
Forfeited (in dollars per share)	11.83
Outstanding at end period (in dollars per share)	10.77
Exercisable (in dollars per share)	$ 7.16

Stock-Based Compensation - Restricted Stock Awards (Details) - Restricted Stock	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Shares
Unvested balance, at beginning of period (in shares) \| shares	0
Issued (in shares) \| shares	456,845
Forfeited (in shares) \| shares	(11,400)
Unvested balance, at end of period (in shares) \| shares	445,445
Weighted- Average Grant -Date Fair Value
Beginning of period (in dollars per share) \| $ / shares	$ 0
Issued (in dollars per share) \| $ / shares	12.05
Forfeited (in dollars per share) \| $ / shares	11.62
End of period (in dollars per share) \| $ / shares	$ 12.06

Leases - Additional Information (Details) $ in Millions	Mar. 16, 2022 USD ($) sqft $ / sqft	Sep. 30, 2022 USD ($) sqft
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	240.00
Operating leases additional allowance	$ 1.6
Tenant allowance rentable square foot of premises per annum \| $ / sqft	20.00
Interest rate for additional improvements allowance	8.00%
Operating lease related expenses prior to commencement		$ 13.7
Massachusetts
Lessee, Lease, Description [Line Items]
Number of square feet \| sqft		42,046
Massachusetts \| IDB
Lessee, Lease, Description [Line Items]
Number of square feet \| sqft	81,442

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
Leases [Abstract]
Operating lease cost	$ 2,294	$ 6,479
Variable lease cost	0	0
Total lease cost	$ 2,294	$ 6,479

Leases - Cash flow information (Details) $ in Thousands	9 Months Ended
Leases - Cash flow information (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Leases [Abstract]
Operating cash flows used for operating leases (in thousands)	$ 6,306
Weighted average remaining lease term	3 years 2 months 12 days
Weighted average discount rate	3.81%

Leases - Maturities of Operating Lease Liabilities (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Maturity of Lease Liability
2022 (excluding the nine-months ended September 30, 2022)	$ 2,268
2023	9,219
2024	9,494
2025	8,650
Thereafter	0
Total lease payments	29,631
Less: imputed interest	(1,680)
Present value of operating lease liabilities	$ 27,951

Net Loss per Share - Computation of EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Numerator:
Net loss attributable to common stockholders	$ (25,137)	$ (23,179)	$ (21,671)	$ (14,430)	$ (9,901)	$ (8,380)	$ (69,987)	$ (32,711)
Denominator:
Weighted-average common shares outstanding, basic (in shares)	31,298,052			1,475,170			31,273,612	1,352,721
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.80)			$ (9.78)			$ (2.24)	$ (24.18)
Numerator:
Net loss attributable to common stockholders	$ (25,137)	$ (23,179)	$ (21,671)	$ (14,430)	$ (9,901)	$ (8,380)	$ (69,987)	$ (32,711)
Denominator:
Weighted-average common shares outstanding, diluted (in shares)	31,298,052			1,475,170			31,273,612	1,352,721
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.80)			$ (9.78)			$ (2.24)	$ (24.18)

- Definition

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

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- Definition

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

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Net Loss per Share - Antidilutive securities (Details) - shares	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	5,515,912	21,691,266
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)	445,445	0
Unvested shares from early exercises
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	67,737	136,520
Stock options to purchase common stock
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	5,002,730	2,369,563