0001689375-24-000016 | 10-K | XBRL Viewer

Summary of Significant Accounting Policies - Segment Information (Details)	12 Months Ended
	Dec. 31, 2023 segment
Accounting Policies [Abstract]
Number of segments	1

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Collaboration revenue	$ 129,013
Operating expenses:
Research and development	99,884	$ 66,609
General and administrative	32,291	30,639
Total operating expenses	132,175	97,248
Loss from operations	(3,162)	(97,248)
Other income:
Interest and other income	15,218	2,632
Total other income	15,218	2,632
Income (loss) before income taxes	12,056	(94,616)
Income tax	(18,741)	0
Net loss	$ (6,685)	$ (94,616)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.20)	$ (3.02)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.20)	$ (3.02)
Weighted-average common shares outstanding, basic (in shares)	33,050,319	31,293,312
Weighted-average common shares outstanding, diluted (in shares)	33,050,319	31,293,312
Other comprehensive loss:
Unrealized income (loss) on marketable securities, net of tax of $0	$ 2,252	$ (2,057)
Total other comprehensive income (loss)	2,252	(2,057)
Total comprehensive loss	$ (4,433)	$ (96,673)

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2023

Accrued Expenses and Other Current Liabilities

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following at December 31 (in thousands):


	2023		2022
Employee compensation and benefits	$	6,660	$	5,063
External research and development expenses	2,894		1,157
General and administrative professional service expenses	767		925
Other	1,004		431
Total accrued expenses and other current liabilities	$	11,325	$	7,576

Common Stock and Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Schedule of Shares Reserved for Future Issuance under equity compensation plans

The Company has reserved the following shares of common stock for future issuance under equity compensation plans at December 31:


	2023	2022
Exercise of outstanding stock options	5,414,360	5,028,850
Vesting of outstanding restricted stock	1,268,461	463,964
Future awards under the 2021 Stock Option and Incentive Plan	1,697,832	1,976,758
Future awards under the 2021 Employee Stock Purchase Plan	839,539	563,115
Total shares of authorized common stock reserved for future issuance	9,220,192	8,032,687

Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 3,617	$ 32,148
Research and development tax credit carryforwards	2,706	7,679
Intangible assets	2,326	1,142
Capitalized research and development expenses	32,803	15,747
Deferred revenue	36,726	0
Lease liability	22,581	7,031
Stock compensation	1,709	1,109
Other	0	34
Total deferred tax assets	102,468	64,890
Deferred tax liabilities:
Property and equipment	(2,044)	(298)
Right-of-use asset	(22,237)	(6,869)
Prepaid expenses	(281)	(304)
Total deferred tax liabilities	(24,562)	(7,471)
Valuation allowance	(77,906)	(57,419)
Net deferred tax assets	$ 0	$ 0

Marketable Securities - Additional Information (Details)	Dec. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Number of securities \| security	20	32
Market value of marketable securities	$ 101,700,000	$ 143,600,000
Allowance for credit loss	0
Interest receivable	$ 1,700,000	$ 600,000
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Current, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets

Stock Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2022
Stock-based compensation
Vesting of early exercised options (in shares)		14,745	53,741
Unvested early exercises of stock options		$ 100	$ 200
Proceeds from exercise of stock options		$ 443	$ 284
Restricted stock units, vested (in shares)		138,361
ESPP
Stock-based compensation
Stock authorized for issuance (in shares)		839,539	563,115
Stock Options
Stock-based compensation
Aggregate intrinsic value of stock options exercised		$ 2,100	$ 1,000
Proceeds from exercise of stock options		$ 1,200	$ 200
Weighted-average grant-date fair value of stock options granted (in dollars per share)		$ 9.23	$ 7.51
Unrecognized compensation cost		$ 20,700
Unrecognized compensation cost, weighted-average period for recognition		2 years 2 months 12 days
Outstanding restricted stock
Stock-based compensation
Vesting period		4 years
Unrecognized compensation cost		$ 15,100
Unrecognized compensation cost, weighted-average period for recognition		3 years 2 months 1 day
Outstanding restricted stock \| Tranche One
Stock-based compensation
Vesting percentage		25.00%
Outstanding restricted stock \| Tranche Two
Stock-based compensation
Vesting percentage		25.00%
Outstanding restricted stock \| Tranche Three
Stock-based compensation
Vesting percentage		25.00%
Outstanding restricted stock \| Tranche Four
Stock-based compensation
Vesting percentage		25.00%
2021 Plan
Stock-based compensation
Shares annual increase as percentage		4.00%
Stock authorized for issuance (in shares)		6,336,068	5,262,917
2016 Stock Plan
Stock-based compensation
Stock authorized for issuance (in shares)		2,044,585	2,206,655
2021 Employee Stock Purchase Plan \| ESPP
Stock-based compensation
Shares annual increase as percentage	1.00%
Stock authorized for issuance (in shares)	278,762
Shares remaining available for future issuance (in shares)	557,524

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Income (loss) before income taxes	$ 12,056	$ (94,616)
Total income tax provision	18,741	0
Net operating loss carryforwards subject to expiration	$ 0
Annual deduction in relation to taxable income (as percent)	80.00%
Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Increase in valuation allowance	$ 20,500	$ 28,500
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	14,600
Tax credit carryforwards	2,100
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	8,700
Tax credit carryforwards	$ 800

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2023

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):


	Year Ended December 31,
	2023		2022
Numerator:
Net loss attributable to common stockholders	$	(6,685)	$	(94,616)
Denominator:
Weighted‑average common shares outstanding, basic and diluted	33,050,319		31,293,312
Net loss per share attributable to common stockholders, basic and diluted	$	(0.20)	$	(3.02)

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:


	Year Ended December 31,
	2023	2022
Unvested restricted common stock	1,268,461	463,964
Unvested shares from early exercises	14,745	53,741
Stock options to purchase common stock	5,414,360	5,028,850
	6,697,566	5,546,555

Leases - Additional Information (Details) $ in Thousands		1 Months Ended	12 Months Ended
Leases - Additional Information (Details) $ in Thousands	Mar. 16, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) sqft	Apr. 30, 2023 USD ($)	Mar. 16, 2022 USD ($)	Mar. 16, 2022 vote	Mar. 16, 2022 sqft
Commitments and Contingencies
Number of square feet \| sqft			23,189				65,000
Fixed monthly rental payments	$ 500
Rental expenses annual increase	3.00%
Right-of-use assets, operating leases		$ 25,340	$ 81,490
Present value of operating lease liabilities			68,230
Term of contract	10 years
Lease term	5 years
Tenant improvements allowance					$ 19,500
Operating leases additional allowance	$ 1,600
Restricted cash		$ 3,950	3,950
Fixed rental payments			$ 500
Remaining lease period			3 years
Security deposit			$ 700
Sublease term		3 years
Lease term extension		6 months
Sublease income		$ 200
Sublease fixed rental rate, percentage increase per annum		3.00%
Letter of credit received in place of a security deposit		$ 500
Sublease income			1,500
Other Current Assets
Commitments and Contingencies
Security deposit			300
Other Noncurrent Assets
Commitments and Contingencies
Security deposit			400
IDB
Commitments and Contingencies
Right-of-use assets, operating leases			$ 13,900	$ 77,600
Present value of operating lease liabilities				$ 63,600
Massachusetts \| IDB
Commitments and Contingencies
Number of square feet						81,229	81,229

Income Taxes - Reconciliation of U.S. Federal Statutory Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate	21.00%	21.00%
State income taxes, net of federal benefit	5.10%	5.50%
Federal and state research and development tax credits	(50.30%)	5.00%
Non-deductible stock compensation and non-taxable items	11.30%	(1.40%)
Change in deferred tax asset valuation allowance	170.30%	(30.10%)
Change in state tax rates	(1.90%)	0.00%
Effective income tax rate	155.50%	0.00%

Stock Based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Number of Shares
Outstanding at beginning of period (in shares) \| shares	5,028,850
Granted (in shares) \| shares	799,144
Exercised (in shares) \| shares	(214,078)
Forfeited (in shares) \| shares	(199,556)
Outstanding at end period (in shares) \| shares	5,414,360
Exercisable (in shares) \| shares	3,297,593
Weighted‑Average Exercise Price
Outstanding at beginning period (in dollars per share) \| $ / shares	$ 10.95
Granted (in dollars per share) \| $ / shares	13.85
Exercised (in dollars per share) \| $ / shares	5.54
Forfeited (in dollars per share) \| $ / shares	15.63
Outstanding at end period (in dollars per share) \| $ / shares	11.42
Exercisable (in dollars per share) \| $ / shares	$ 9.49
Weighted‑Average Remaining Contractual Term
Outstanding (in years)	7 years 9 months 10 days
Exercisable (in years)	7 years 3 months 3 days
Aggregate Intrinsic Value
Outstanding \| $	$ 25,569
Exercisable \| $	$ 21,529

Common Stock and Preferred Stock

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Common Stock and Preferred Stock

Common Stock

As of both December 31, 2023 and December 31, 2022, the Company’s certificate of incorporation, as amended and restated effective upon the completion of the IPO, authorized the Company to issue 150,000,000 shares of common stock, par value $0.0001 per share. The holders of common stock are entitled to one vote for each share held on all matters submitted to a vote of the stockholders. The holders of common stock do not have any cumulative voting rights. Holders of common stock are entitled to receive ratably any dividends declared by the board of directors out of funds legally available for that purpose, subject to any preferential dividend rights of any outstanding preferred stock. Common stock has no preemptive rights, conversion rights or other subscription rights or redemption or sinking fund provisions. In the event of liquidation, dissolution or winding up, holders of common stock will be entitled to share ratably in all assets remaining after payment of all debts and other liabilities and any liquidation preference of any outstanding preferred stock.

In February 2023, in connection with the closing of the Vertex Agreement, the Company and Vertex also closed their Stock Purchase Agreement for the sale and issuance of 1,618,613 shares of Entrada's common stock (the “Shares”) to Vertex for an aggregate purchase price of approximately $26.3 million or $16.26 per share. See Note 12, Collaboration and License Agreements, for further discussion of the Company's accounting for the shares sold in connection with the closing of the Vertex Agreement.

In September 2023, the Company entered into a sales agreement (the Sales Agreement) with Cowen and Company, LLC, acting as the Company's agent and/or principal (the Sales Agent), with respect to an "at the market offering" program under which the Company may, from time to time, at its sole discretion, issue and sell shares of its common stock having an aggregate offering price of up to $150.0 million through the Sales Agent. During the year ended December 31, 2023, there have been no sales of common stock pursuant to the Sales Agreement.

Shares Reserved for Future Issuance under Equity Compensation Plans

The Company has reserved the following shares of common stock for future issuance under equity compensation plans at December 31:


	2023	2022
Exercise of outstanding stock options	5,414,360	5,028,850
Vesting of outstanding restricted stock	1,268,461	463,964
Future awards under the 2021 Stock Option and Incentive Plan	1,697,832	1,976,758
Future awards under the 2021 Employee Stock Purchase Plan	839,539	563,115
Total shares of authorized common stock reserved for future issuance	9,220,192	8,032,687

Preferred Stock

As of both December 31, 2023 and December 31, 2022, 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. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting, or the designation of, such series, any or all of which may be greater than the rights of common stock. As of both December 31, 2023 and December 31, 2022, there were no shares of undesignated preferred stock issued or outstanding.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Marketable Securities - Amortized Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amortized Cost
Total available-for-sale securities	$ 284,172	$ 145,612
Unrealized Gains (Losses)
Unrealized Gains	265	0
Unrealized Losses	(70)	(2,057)
Fair Value
Marketable securities	284,367	143,555
One Year or Less
Amortized Cost
Total securities with a maturity of one year or less	260,966	142,170
Unrealized Gains (Losses)
Unrealized Gains	127	0
Unrealized Losses	(70)	(1,933)
Fair Value
Total securities with a maturity of one year or less	261,023	140,237
One to Two Years
Amortized Cost
Total securities with a maturity of greater than one year	23,206	3,442
Unrealized Gains (Losses)
Unrealized Gains	138	0
Unrealized Losses	0	(124)
Fair Value
Total securities with a maturity of greater than one year	23,344	3,318
U.S. government agency securities and treasuries \| One Year or Less
Amortized Cost
Total securities with a maturity of one year or less	235,500	100,555
Unrealized Gains (Losses)
Unrealized Gains	127	0
Unrealized Losses	(41)	(1,159)
Fair Value
Total securities with a maturity of one year or less	235,586	99,396
U.S. government agency securities and treasuries \| One to Two Years
Amortized Cost
Total securities with a maturity of greater than one year	15,537	0
Unrealized Gains (Losses)
Unrealized Gains	45	0
Unrealized Losses	0	0
Fair Value
Total securities with a maturity of greater than one year	15,582	0
Corporate debt securities \| One Year or Less
Amortized Cost
Total securities with a maturity of one year or less	25,466	41,615
Unrealized Gains (Losses)
Unrealized Gains	0	0
Unrealized Losses	(29)	(774)
Fair Value
Total securities with a maturity of one year or less	25,437	40,841
Corporate debt securities \| One to Two Years
Amortized Cost
Total securities with a maturity of greater than one year	7,669	3,442
Unrealized Gains (Losses)
Unrealized Gains	93	0
Unrealized Losses	0	(124)
Fair Value
Total securities with a maturity of greater than one year	$ 7,762	$ 3,318

Net Loss per Share

12 Months Ended

Dec. 31, 2023

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):


	Year Ended December 31,
	2023		2022
Numerator:
Net loss attributable to common stockholders	$	(6,685)	$	(94,616)
Denominator:
Weighted‑average common shares outstanding, basic and diluted	33,050,319		31,293,312
Net loss per share attributable to common stockholders, basic and diluted	$	(0.20)	$	(3.02)

Common Stock Equivalents


	Year Ended December 31,
	2023	2022
Unvested restricted common stock	1,268,461	463,964
Unvested shares from early exercises	14,745	53,741
Stock options to purchase common stock	5,414,360	5,028,850
	6,697,566	5,546,555

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (6,685)	$ (94,616)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	2,841	1,895
Stock‑based compensation expense	13,111	9,895
Net amortization of premium (accretion of discount) on marketable securities	(5,779)	151
Changes in operating assets and liabilities:
Collaboration receivable	(5,878)	0
Prepaid expenses and other current assets	8,622	(14,022)
Right-of-use assets, operating leases	11,989	7,651
Other non-current assets	(11,563)	(4,338)
Accounts payable	(2,805)	5,287
Accrued expenses and other current liabilities	3,812	1,762
Income taxes payable	4,024	0
Deferred revenue	139,976	0
Operating lease liabilities	(11,862)	(7,451)
Net cash provided by (used in) operating activities	139,803	(93,786)
Cash flows from investing activities:
Purchases of property and equipment	(5,614)	(2,887)
Purchases of marketable securities	(407,207)	(221,977)
Maturities of marketable securities	274,426	76,214
Net cash used in investing activities	(138,395)	(148,650)
Cash flows from financing activities:
Proceeds from issuance of common stock in connection with the Vertex Agreement	19,407	0
Proceeds from exercise of stock options	1,187	195
Proceeds from issuance of common stock under the employee stock purchase plan	443	284
Net cash provided by financing activities	21,037	479
Net increase (decrease) in cash, cash equivalents and restricted cash	22,445	(241,957)
Cash, cash equivalents and restricted cash at beginning of year	49,107	291,064
Cash, cash equivalents and restricted cash at end of year	71,552	49,107
Supplemental cash flow disclosures:
Purchases of property and equipment included in accounts payable and accrued expenses	208	88
Right-of-use assets obtained in exchange for operating lease liabilities	77,584	0
Right-of-use assets surrendered as part of lease modification	9,445	0
Recognition of right-of-use assets upon adoption of ASC 842	0	32,991
Transfer of deposits for equipment from operating to investing cash flows	617	495
Vesting of options early exercised subject to repurchase	91	135
Cash paid for income taxes	$ 14,717	$ 0

Stock Based Compensation - Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Stock-based compensation
Share-based compensation expense	$ 13,111	$ 9,895
Research and development expenses
Stock-based compensation
Share-based compensation expense	6,169	4,166
General and administrative expenses
Stock-based compensation
Share-based compensation expense	6,942	5,729
Stock Options
Stock-based compensation
Share-based compensation expense	9,887	8,648
Restricted Stock Units
Stock-based compensation
Share-based compensation expense	3,015	1,106
ESPP
Stock-based compensation
Share-based compensation expense	$ 209	$ 141

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Income Tax Expense

The components of the income tax expense for the years ended December 31, 2023 and 2022 (in thousands) were:


	Year Ended December 31,
	2023		2022
Current:
Federal	$	14,962	$	—
State	3,779		—
Foreign	—		—
Total current tax provision	18,741		—
Deferred:
Federal	—		—
State	—		—
Foreign	—		—
Total deferred tax provision	—		—
Total income tax provision	$	18,741	$	—

Schedule of Reconciliation of U.S. Federal Statutory Income Tax Rate to Effective Income Tax Rate

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


	Year Ended December 31,
	2023	2022
Federal statutory income tax rate	21.0%	21.0%
State income taxes, net of federal benefit	5.1	5.5
Federal and state research and development tax credits	-50.3	5.0
Non-deductible stock compensation and non-taxable items	11.3	(1.4)
Change in deferred tax asset valuation allowance	170.3	(30.1)
Change in state tax rates	(1.9)	—
Effective income tax rate	155.5%	—%

Schedule of Net Deferred Tax Assets

Net deferred tax assets as of December 31, 2023 and 2022 consisted of the following (in thousands):


	December 31,
	2023		2022
Deferred tax assets:
Net operating loss carryforwards	$	3,617	$	32,148
Research and development tax credit carryforwards	2,706		7,679
Intangible assets	2,326		1,142
Capitalized research and development expenses	32,803		15,747
Deferred revenue	36,726		—
Lease liability	22,581		7,031
Stock compensation	1,709		1,109
Other	—		34
Total deferred tax assets	102,468		64,890
Deferred tax liabilities:
Property and equipment	(2,044)		(298)
Right-of-use asset	(22,237)		(6,869)
Prepaid expenses	(281)		(304)
Total deferred tax liabilities	(24,562)		(7,471)
Valuation allowance	(77,906)		(57,419)
Net deferred tax assets	$	—	$	—

Nature of the Business	12 Months Ended
Nature of the Business	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	Nature of the Business Organization Entrada Therapeutics, Inc. (Entrada or the Company) is a clinical-stage biopharmaceutical company aiming to transform the lives of patients by establishing a new class of medicines which engage intracellular targets that have long been considered inaccessible. The Company’s Endosomal Escape Vehicle (EEV™)-therapeutics are designed to enable the efficient delivery of a wide range of therapeutics into a variety of organs and tissues, resulting in an improved therapeutic index. 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 consolidated financial statements are issued. The Company has incurred significant net losses since its inception, including net losses of $6.7 million and $94.6 million for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, the Company had an accumulated deficit of $195.0 million. To date, the Company has funded its operations primarily through the sale of equity securities and collaboration payments. Other than the recognition of revenue related to the collaboration payments received during the year ended December 31, 2023, 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 $352.0 million as of December 31, 2023 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 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.

Marketable Securities

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

The following is a summary of the Company's marketable securities at December 31, 2023 and December 31, 2022 (in thousands).


	As of December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. government agency securities and treasuries	$	235,500	$	127	$	(41)	$	235,586
Corporate debt securities	25,466		—		(29)		25,437
Total securities with a maturity of one year or less	$	260,966	$	127	$	(70)	$	261,023

U.S. government agency securities and treasuries	15,537		45		—		15,582
Corporate debt securities	7,669		93		—		7,762
Total securities with a maturity of greater than one year	$	23,206	$	138	$	—	$	23,344
Total available-for-sale securities	$	284,172	$	265	$	(70)	$	284,367


	As of December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. government agency securities and treasuries	$	100,555	$	—	$	(1,159)	$	99,396
Corporate debt securities	41,615		—		(774)		40,841
Total securities with a maturity of one year or less	$	142,170	$	—	$	(1,933)	$	140,237

U.S. government agency securities and treasuries	—		—		—		—
Corporate debt securities	3,442		—		(124)		3,318
Total securities with a maturity of greater than one year	$	3,442	$	—	$	(124)	$	3,318
Total available-for-sale securities	$	145,612	$	—	$	(2,057)	$	143,555

As of December 31, 2023, the Company had 20 marketable securities with a total fair market value of $101.7 million in an unrealized loss position. As of December 31, 2022, the Company had 32 marketable securities with a total fair market value of $143.6 million in an unrealized loss position.

The Company believes that any unrealized losses associated with the decline in value of its securities are temporary and primarily related to the change in market interest rates since purchase. The Company believes that it is more likely than not that it will be able to hold its debt securities to maturity and that there was no material change in the credit risk of the above instruments since January 1, 2023. Therefore, the Company anticipates a full recovery of the amortized cost basis of its debt securities at maturity and no allowance for credit losses was recognized.

As of December 31, 2023 and December 31, 2022, $1.7 million and $0.6 million, respectively, of accrued interest receivable was included in prepaid expenses and other current assets.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Presentation

The accompanying consolidated financial statements reflect the operations of the Company 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 ASC and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB).

Principles of Consolidation

The accompanying consolidated financial statements include those of the Company and its wholly-owned subsidiary. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, estimates related to revenue recognition, accrual and prepayment of research and development expenses, the valuation of stock-based compensation and income taxes. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions.

Segment Information

The Company manages its operations as a single segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purposes of assessing performance and making operating decisions.

Revenue Recognition

To date, all revenue has been generated from the Company's Strategic Collaboration and License Agreement with Vertex, which closed in February 2023 and was amended in October 2023 (Vertex Agreement), and falls within the scope of ASC Topic 606, "Revenue from Contracts with Customers" (ASC 606), under which the Company licensed rights to VX-670 and performs research and development services. The terms of this arrangement includes a non-refundable upfront payment, reimbursement for research and development costs; development, regulatory, and commercial milestone payments; and royalties on net sales of licensed products.

Revenue Recognition

Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer.

For contracts within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered separate performance obligations. The identification of material rights requires judgments related to the determination of the value of the underlying license relative to the option exercise price, including assumptions about technical feasibility and the probability of developing a candidate that would be subject to the option rights. The exercise of a material right is accounted for as a contract modification for accounting purposes.

The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such promised goods or services are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct

provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). In assessing whether a promised good or service is distinct, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, an entity is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct.

The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. For contracts within the scope of ASC 606 that contain elements within the scope of a different ASC Topic, the Company excludes the fair value such elements from the transaction price.

If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment as a change in estimate.

If an arrangement includes development or regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price in the period in which the Company deems the milestone to be probable. Milestone payments that are not within the Company’s control or a customer's control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received.

The transaction price is allocated to the identified performance obligations in proportion to their standalone selling prices (SSP) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations may require significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. The Company validates the SSP for performance obligations by evaluating whether changes in the key assumptions used to determine the SSP will have a significant effect on the allocation of arrangement consideration between multiple performance obligations.

For arrangements with licenses of intellectual property that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty has been allocated has been satisfied. Up-front and milestone payments are recorded as deferred revenue upon receipt or when due until the Company performs its obligations under these arrangements.

Amounts are recorded as a collaboration receivable when the Company's right to consideration is unconditional. To date, the Company has not recorded any credit losses on its collaboration receivables.

The Company then recognizes the revenue allocated to each performance when (or as) each performance obligation is satisfied, either at a point in time or over time. Any over time recognition is based on the use of an output or input method.

Concentrations of Credit Risk and Off-Balance Sheet Risk

Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash, cash equivalents, restricted cash and marketable securities. Periodically, the Company may maintain deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality, and the Company has not experienced any losses on these deposits. The Company’s marketable securities primarily consist of corporate bonds and U.S. government agency securities and treasuries, and potentially subject the Company to concentrations of credit risk. Our cash management and investment policy limits investment instruments to investment-grade securities with the objective to preserve capital and to maintain liquidity until the funds can be used in business operations

Cash, Cash Equivalents, and Restricted Cash

The Company considers all highly liquid investments with a remaining maturity of 90 days or less at the date of purchase to be cash equivalents. At December 31, 2023 and 2022 cash and cash equivalents include standard checking accounts and money market account funds that invest primarily in U.S. government-backed securities and treasuries.

As of December 31, 2023 and 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. 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):


	December 31, 2023		December 31, 2022
Cash and cash equivalents	$	67,602	$	45,157
Restricted cash	3,950		3,950
Total cash, cash equivalents and restricted cash	$	71,552	$	49,107

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 or accreted to investment income and/or expense over the life of the underlying investment. All of the Company’s marketable 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 interest and other income in our consolidated statement of operations.

The Company assesses impairment for its marketable securities under the available-for-sale debt security impairment model in ASC 326 as of each reporting date. Based on the model, we determine if a portion of any decline in fair value below carrying value is the result of a credit loss. The Company records credit losses in the consolidated statements of operations and comprehensive loss as credit loss expense within interest and other income, which is limited to the difference between the fair value and the amortized cost of the security. To date, the Company has not recorded any credit losses on its available-for-sale debt securities.

Accrued interest receivable related to the Company's available-for-sale debt securities is presented within prepaid expenses and other current assets on the Company's consolidated balance sheets. The Company has elected the practical expedient available to exclude accrued interest receivable from both the fair value and the amortized cost basis of available-for-sale debt securities for the purposes of identifying and measuring any impairment. The Company writes off accrued interest receivable once it has determined that the asset is not realizable. Any write offs of accrued interest receivable are recorded by reversing interest income, recognizing credit loss expense, or a combination of both. To date, the Company has not written off any accrued interest receivables associated with its marketable securities.

Fair Value Measurements

ASC Topic 820, Fair Value Measurement (ASC 820), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the assets or liability and are developed based on the best information available under the circumstances. ASC 820 identifies fair value as the price that would be received to sell an asset or paid to transfer a liability, in an orderly transaction between market participants at the measurement date.

As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tiered value hierarchy that distinguishes between the following:

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

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

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

To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of financial instruments between levels during the years ended December 31, 2023 and 2022. The carrying amounts of accounts payable and accrued expenses approximate their fair values due to their short-term nature.

Property and Equipment

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


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Computer equipment			3 years
Leasehold improvements			Lesser of estimated useful life or remaining lease term

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

Leases

At the inception of a lease arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present in the arrangement. Leases with a term greater than one year are recognized on the balance sheet as right-of-use assets and current and non-current lease liabilities, as applicable. The Company has elected not to recognize leases with an original term of one year or less on the balance sheet.

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. Prospectively, the Company adjusts the right-of-use assets for straight-line rent expense or any incentives received and remeasures 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. Lease expense for lease payments is recognized on a straight-line basis over the assigned lease term.

Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. Changes to the terms and conditions of a lease that result in a change in the scope of or the consideration for the lease result in a lease modification. A lease modification that 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 is treated as a separate contract. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. For any lease modifications that aren't accounted for as separate contracts, the Company remeasures its right-of-use assets and lease liabilities as of the modification date. 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.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets, which consist primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset.

Deferred Offering Costs

The Company capitalizes incremental legal, professional accounting and other third-party fees that are incurred in the course of preparing for a financing as other non-current assets until the offering is consummated. At the time of the completion of the offering, the costs are reclassified as a reduction of the proceeds of the financing as part of additional paid-in-capital. Should the offering be terminated, deferred offering costs are charged to operations during the period in which the offering is terminated.

Contingencies

The Company records liabilities for legal and other contingencies when information available to the Company indicates that it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. Legal costs in connection with legal and other contingencies are expensed as costs are incurred.

Indemnification Agreements

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

Research and Development Expenses

Research and development costs are charged to expense as incurred. Research and development costs consist of direct and allocated costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, third-party license fees related to technology with no alternative future use, laboratory supplies, depreciation, manufacturing expenses, preclinical expenses, clinical expenses, consulting and other contracted services. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed or until it is no longer expected that the goods will be delivered or the services rendered.

The Company has entered into various research and development related contracts with third parties. These agreements are cancellable with prior written notice, and related fees are recorded as research and development expenses as incurred. Payments for these agreements are based on the terms of the individual contracts, which may differ from the pattern of costs incurred, and payments made in advance of performance are reflected in the accompanying consolidated balance sheets as prepaid and other assets or accrued liabilities. When evaluating the adequacy of the accrued liabilities and prepaid expenses, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued and prepaid balances at the end of any reporting period. Actual results could differ from the Company’s estimates.

Patent Costs

All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses.

Stock-Based Compensation

The Company’s stock-based compensation program allows for grants of stock options and restricted stock units. Grants are awarded to employees and non-employees, including the Company’s board of directors.

The Company accounts for its stock-based compensation in accordance with ASC Topic 718, Compensation-Stock Compensation (ASC 718). ASC 718 requires all stock-based payments to employees, non-employees and directors, to be recognized as expense in the consolidated statements of operations based on their grant date fair values. The Company estimates the fair value of options granted using the Black-Scholes option-pricing model (Black-Scholes) for stock option grants to both employees and non-employees. The fair value of the Company’s common stock is used to determine the fair value of restricted stock units.

The Company’s stock-based compensation awards are subject to service-based vesting conditions. Compensation expense related to awards to employees, directors and non-employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term.

Black-Scholes requires inputs based on certain subjective assumptions, including (i) the expected stock price volatility, (ii) the expected term of the award, (iii) the risk-free interest rate and (iv) expected dividends. The Company determines the expected volatility using the historical volatility of a peer group of comparable publicly traded companies with comparable characteristics and with historical share price information that approximates the expected term of the stock-based awards. The Company uses the simplified method as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term for options granted to employees and non-employees whereby, the expected term equals the arithmetic average of the vesting term and the original contractual term of the options due to its lack of sufficient historical data. The risk-free interest rate is based on U.S. Treasury securities with a maturity date commensurate with the expected term of the associated award. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. The Company recognizes forfeitures as they occur.

Prior to the Company’s IPO, there was no public market for its common stock, and consequently, the estimated fair value of its common stock was determined by the board of directors as of the date of each option grant, with input from management, considering third-party valuations of its common stock as well as its board of directors’ assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent third-party valuation through the date of the grant. These third-party valuations were performed in accordance

with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (Practice Aid). The Practice Aid identifies various available methods for allocating the enterprise value across classes of series of capital stock in determining the fair value of the Company’s common stock at each valuation date.

Subsequent to the Company’s IPO, the fair value of the common stock underlying the stock-based awards is the closing price of the Company’s common stock on the date of grant.

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

Income Taxes

Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes (ASC 740), which provides for deferred taxes using an asset and liability approach. The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

Net Loss per Share

The Company follows the two-class method when computing net loss per share, as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. During periods of loss, there is no allocation required under the two-class method since the participating securities do not have a contractual obligation to fund the losses of the Company.

Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents. Given that the Company recorded a net loss for each of the periods presented, there is no difference between basic and diluted net loss per share since the effect of common stock equivalents would be antidilutive and are, therefore, excluded from the diluted net loss per share calculation.

Comprehensive Loss

Comprehensive loss includes net loss and other comprehensive loss. For both the year ended December 31, 2023 and the year ended December 31, 2022, comprehensive loss consists of net loss and changes in unrealized gains and losses on marketable securities.

Recently Adopted and Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326)

Effective January 1, 2023, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). This ASU requires that credit losses for financial instruments measured at amortized cost be reported using an expected losses model rather than the incurred losses model that was previously used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, this standard requires allowances to be recorded for any credit losses instead of reducing the amortized cost of the investment. ASU 2016-13 limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases. This guidance did not have an impact on the Company's consolidated financial statements.

ASU No. 2022-03, Fair Value Measurement (Topic 820)

Effective January 1, 2023, the Company adopted ASU No. 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. This ASU clarifies that a contractual restriction on the sale of an investment in an equity security is not considered part of the unit of account of the equity security and, therefore, is not considered in measuring its fair value. For additional information regarding the impact of the adoption of this ASU on our consolidated financial statements, refer to Note 12, Collaboration and License Agreements.

Recently Issued Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and non-public companies, the Company can adopt the new or revised standard at the time non-public companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for non-public companies. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial statements and disclosures.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which is intended to provide enhancements to annual income tax disclosures. In particular, the standard will require more detailed information in the income tax rate reconciliation, as well as the disclosure of income taxes paid disaggregated by jurisdiction, among other enhancements. The standard is effective for years beginning after December 15, 2024 and early adoption is permitted. The Company is currently evaluating the impact of the standard on the presentation of its consolidated financial statements and footnotes.

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-based Compensation Expense

The Company recognized stock-based compensation expense in the consolidated statements of operations and comprehensive loss, by award type, as follows (in thousands):


	Year ended December 31,
	2023		2022
Stock Options	$	9,887	$	8,648
Restricted Stock Units	3,015		1,106
ESPP	209		141
Total	$	13,111	$	9,895

Stock-based compensation expense recorded as research and development and general and administrative expenses in the consolidated statements of operations and comprehensive loss is as follows (in thousands):


	Year ended December 31,
	2023		2022
Research and development expenses	$	6,169	$	4,166
General and administrative expenses	6,942		5,729
Total	$	13,111	$	9,895

Schedule of Assumptions Used in the Black-Scholes Option-Pricing Model

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 for the years then ended:


	December 31, 2023	December 31, 2022
Risk‑free interest rate	4.09%	2.20%
Expected volatility	72%	71%
Expected dividend yield	—	—
Expected term (in years)	6.01	6.04

Schedule of the Stock Option Activity

The following table summarizes the Company’s stock option activity since December 31, 2022:


	Number of Shares	Weighted‑Average Exercise Price		Weighted‑Average Remaining Contractual Term	Aggregate Intrinsic Value(2)
				(in years)	(in thousands)
Outstanding as of December 31, 2022	5,028,850	$	10.95
Granted	799,144	13.85
Exercised	(214,078)	5.54
Forfeited	(199,556)	15.63
Outstanding as of December 31, 2023	5,414,360	$	11.42	7.78	$	25,569
Exercisable as of December 31, 2023(1)	3,297,593	$	9.49	7.26	$	21,529

(1)This represents the number of vested and unvested options exercisable as of December 31, 2023.

(2)The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the closing price of the Company's common stock at December 31, 2023 for the options that were in the money as of December 31, 2023.

Schedule of Unvested Restricted Stock

A summary of restricted stock activity during the year ended December 31, 2023 is as follows:


	Shares	Weighted‑ Average Grant‑Date Fair Value
Unvested as of December 31, 2022	463,964	$	12.26
Issued	990,167	14.29
Vested	(138,361)	12.30
Forfeited	(47,309)	12.51
Unvested as of December 31, 2023	1,268,461	$	13.83

Summary of Significant Accounting Policies - Contingencies (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Accrued liabilities for legal and other contingencies	$ 0	$ 0

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

The Company recorded $12.1 million of pre-tax book income for the year ended December 31, 2023. The Company recorded a pre-tax book loss for the year ended December 31, 2022. The Company has no foreign operations.

The components of the income tax expense for the years ended December 31, 2023 and 2022 (in thousands) were:


	Year Ended December 31,
	2023		2022
Current:
Federal	$	14,962	$	—
State	3,779		—
Foreign	—		—
Total current tax provision	18,741		—
Deferred:
Federal	—		—
State	—		—
Foreign	—		—
Total deferred tax provision	—		—
Total income tax provision	$	18,741	$	—

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


	Year Ended December 31,
	2023	2022
Federal statutory income tax rate	21.0%	21.0%
State income taxes, net of federal benefit	5.1	5.5
Federal and state research and development tax credits	-50.3	5.0
Non-deductible stock compensation and non-taxable items	11.3	(1.4)
Change in deferred tax asset valuation allowance	170.3	(30.1)
Change in state tax rates	(1.9)	—
Effective income tax rate	155.5%	—%

Net deferred tax assets as of December 31, 2023 and 2022 consisted of the following (in thousands):


	December 31,
	2023		2022
Deferred tax assets:
Net operating loss carryforwards	$	3,617	$	32,148
Research and development tax credit carryforwards	2,706		7,679
Intangible assets	2,326		1,142
Capitalized research and development expenses	32,803		15,747
Deferred revenue	36,726		—
Lease liability	22,581		7,031
Stock compensation	1,709		1,109
Other	—		34
Total deferred tax assets	102,468		64,890
Deferred tax liabilities:
Property and equipment	(2,044)		(298)
Right-of-use asset	(22,237)		(6,869)
Prepaid expenses	(281)		(304)
Total deferred tax liabilities	(24,562)		(7,471)
Valuation allowance	(77,906)		(57,419)
Net deferred tax assets	$	—	$	—

The Company recorded income tax expense of $18.7 million for the year ended December 31, 2023. The income tax expense recorded was driven largely by the current tax liability associated with the tax recognition of the Vertex Agreement payments received during 2023. A significant portion of the taxable income related to the collaboration payment is offset by current year expenses and prior year accumulated losses.

As of December 31, 2023, the Company had federal net operating loss carryforwards of $14.6 million, which may be available to offset future taxable income. None of our federal net operating loss carryforwards will expire, but all are limited in their usage to an annual deduction equal to 80% of annual taxable income. In addition, as of December 31, 2023, the Company had state net operating loss carryforwards of $8.7 million, which may be available to offset future taxable income and expire at various dates beginning in 2036. As of December 31, 2023, the Company also had federal and state research and development tax credit carryforwards of $2.1 million and $0.8 million, respectively, which may be available to reduce future tax liabilities and expire at various dates beginning in 2039 and 2035, respectively.

Utilization of the NOLs and research and development tax credit carryforwards may be subject to a substantial annual limitation under Section 382 due to ownership change limitations that have occurred previously or that could occur in the future in accordance with Section 382, as well as similar state provisions. These ownership changes may limit the amount of NOLs and research and development tax credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. If a change in control as defined by Section 382 has occurred at any time since the Company’s formation, utilization of its NOLs or research and development tax credit carryforwards would be subject to an annual limitation under Section 382, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term tax-exempt rate, which could then be subject to additional adjustments, as required. Any limitation may result in expiration of a portion of the NOLs or research and development tax carryforwards before their utilization. The Company has determined that ownership changes have occurred in the past and that certain NOLs and research and development tax credit carryforwards will be subject to limitation.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets, which consist primarily of net operating loss carryforwards and research and development tax credit carryforwards, capitalized research and development expenses and deferred revenue. Management has considered the Company’s history of cumulative net losses incurred since inception, estimated future taxable income, and prudent and feasible tax planning strategies and has concluded that it is more likely than not that the Company will not realize the benefits of federal and state net deferred tax assets. Accordingly, a full valuation allowance has been established against the net deferred tax assets as of December 31, 2023 and 2022. The Company reevaluates the positive and negative evidence at each reporting period.

The valuation allowance increased by $20.5 million and $28.5 million for the years ended December 31, 2023 and 2022, respectively.

The Company assesses the uncertainty in its income tax positions to determine whether a tax position of the Company is more likely than not to be sustained upon examination, including resolution of any related appeals of litigation processes, based on the technical merits of the position. For tax positions meeting the more-likely-than-not threshold, the tax amount recognized in the consolidated financial statements is reduced by the largest benefit that has a greater than 50% likelihood of being realized upon the ultimate settlement with the relevant taxing authority. The Company’s policy is to recognize interest and penalties accrued on any uncertain tax positions as a component of income tax expense, if any, in its consolidated statements of operations. As of December 31, 2023 and 2022, the Company had not recorded any reserves for uncertain tax positions or related interest and penalties.

In 2017, the Tax Cuts and Jobs Act of 2017 (2017 Tax Act) was signed into law. Among other provisions, the 2017 Tax Act requires taxpayers to capitalize and amortize research and experimental (R&E) expenditures under Section 174 for tax years beginning after December 31, 2021. As such, the rule noted became effective for the Company during the year ended December 31, 2022 and resulted in the capitalization of certain R&E costs within its tax provision. The Company will amortize such costs for tax purposes over 5 years if the R&E was performed in the United States and over 15 years if the R&E was performed outside the United States.

The Company files income tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. Due to net operating losses incurred, the Company’s tax returns from inception to date are subject to examination by the taxing authorities.

- 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
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Summary of Significant Accounting Policies - Impairment of Long-Lived Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Impairment losses	$ 0	$ 0

Commitment and Contingencies - Additional Information (Details) - License agreement with a third-party $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) product	Dec. 31, 2022 USD ($)	Jan. 31, 2024 USD ($)	Nov. 30, 2023 USD ($)	Apr. 30, 2023 USD ($)
Other Commitments [Line Items]
Potential milestone payment obligation	$ 2.6			$ 0.1	$ 2.8
Number of licensed products \| product	3
Patent costs	$ 0.1	$ 0.2
Subsequent Event
Other Commitments [Line Items]
Potential milestone payment obligation			$ 0.2
Maximum
Other Commitments [Line Items]
Non-royalty sublicensed consideration (as percent)	15.00%

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Audit Information [Abstract]
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	Boston, Massachusetts

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies In 2018, the Company entered into a definitive license agreement with Ohio State Innovation Foundation (OSIF), an affiliate of The Ohio State University, (OSIF License Agreement) in which OSIF granted the Company an exclusive worldwide, sublicensable license to certain intellectual property under certain patent rights to research, develop, and otherwise commercialize a product generated from the licensed intellectual property. The Company is obligated to make milestone payments of up to $2.6 million upon the occurrence of specified research, development, and commercial activities for each of the first three license products related to the above technology. In addition, OSIF will receive tiered royalty payments on the applicable licensed program and platform products at a percentage ranging in single-digit royalties of net sales subject to reductions and offsets in certain circumstances, as well as a fee on sublicensed consideration of up to 15% of non-royalty sublicensing consideration. Concurrently with the Company entering into and later amending the Vertex Agreement, the Company entered into a sublicense agreement with Vertex, which was amended in October 2023 (Sublicense Agreement). Pursuant to the Sublicense Agreement, the Company granted to Vertex an exclusive sublicense under certain intellectual property licensed to the Company under the OSIF License Agreement. The material terms of the Sublicense Agreement mirror those of the Vertex Agreement, and the payments described in connection with the Vertex Agreement in Note 12, Collaboration and License Agreements, are in consideration for the rights granted under both the Vertex Agreement and Sublicense Agreement. In November 2023, the Company paid approximately $0.1 million for a milestone fee under the OSIF License Agreement. The triggering of all other milestone fees was not considered probable as of December 31, 2023. In April 2023, the Company paid OSIF a sublicense fee of $2.8 million related to the upfront payment received from Vertex in February of 2023. In January 2024, the Company paid OSIF a sublicense fee of $0.2 million related to the Vertex milestone achieved in October of 2023. This amount was accrued for as of December 31, 2023. If the Company receives any additional sublicensing consideration, it will owe additional fees to OSIF pursuant to the terms of the OSIF License Agreement. All costs associated with milestone and sublicense fees are recorded as research and development expenses. For the years ended December 31, 2023 and 2022, the Company reimbursed OSIF for patent costs of $0.1 million and $0.2 million, respectively.

Collaboration and License Agreements - Schedule of Revenue and Performance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies
Collaboration revenue	$ 129,013
Vertex
Commitments and Contingencies
Collaboration revenue	129,013	$ 0
Vertex \| Collaboration services revenue
Commitments and Contingencies
Collaboration revenue	17,508	0
Vertex \| Recognition of upfront and milestone payments
Commitments and Contingencies
Collaboration revenue	$ 111,505	$ 0

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Insider Trading Arrangements

3 Months Ended

12 Months Ended

Dec. 31, 2023

Trading Arrangements, by Individual

Material Terms of Trading Arrangement

From time to time, our officers (as defined in Rule 16a–1(f)) and directors may enter into Rule 10b5-1 or non-Rule 10b5-1 trading arrangements (as each such term is defined in Item 408 of Regulation S-K). During the three months

ended December 31, 2023, our officers and directors took the following actions with respect to 10b5-1 trading arrangements:

Trading Arrangement

Action

Date

Type of Trading Arrangement

Nature of Trading Arrangement

Total Shares to be Sold

Expiration Date

Natarajan Sethuraman (Chief Scientific Officer)

Adopt

12/14/2023

Trading plan intended to satisfy the affirmative defense conditions of Securities Exchange Act Rule 10b5-1(c)

Sale of the Company's common stock pursuant to the terms of the plan

33,856 (1)

4/13/2025

(1)Subject to increase based on any shares not sold under a previous 10b5-1 plan which will expire in April of 2024.

Non-Rule 10b5-1 Arrangement Adopted

false

Rule 10b5-1 Arrangement Terminated

false

Non-Rule 10b5-1 Arrangement Terminated

false

Natarajan Sethuraman [Member]

Trading Arrangements, by Individual

Name

Natarajan Sethuraman

Title

Chief Scientific Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

12/14/2023

Arrangement Duration

486 days

Aggregate Available

33,856

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Unrealized loss on marketable securities, tax	$ 0	$ 0

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Company's contributions to the plan	$ 0.9	$ 0.7

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
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)	33,461,771	31,448,508
Common stock, shares, outstanding (in shares)	33,437,296	31,394,767

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Schedule of Lease Cost

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


	Year ended December 31, 2023
Operating lease cost	$	16,395
Variable lease cost	—
Total lease cost	$	16,395

Supplemental information related to all operating leases was as follows:


Other information	Year ended December 31, 2023
Operating cash flows used for operating leases (in thousands)	$	16,268
Weighted average remaining lease term	8.2 years
Weighted average discount rate	8.13%

Schedule of Maturity of Lease Liability

Future payments due under all operating leases as of December 31, 2023 were as follows (in thousands):


Maturity of lease liabilities	Amount
2024	13,084
2025	13,161
2026	8,826
2027	9,083
2028	9,349
Thereafter	41,091
Total lease payments	$	94,594
Less: imputed interest	(26,364)
Present value of operating lease liabilities	$	68,230

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanThe Company has a defined-contribution plan under Section 401(k) of the Code (401(k) Plan). The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. In 2022, the Company began making matching contributions to the Plan. The Company's contributions were $0.9 million and $0.7 million for the years ended December 31, 2023 and 2022, respectively.

- Definition

The entire disclosure for retirement benefits.

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+ Details

Net Loss per Share - Schedule of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net loss attributable to common stockholders	$ (6,685)	$ (94,616)
Denominator:
Weighted-average common shares outstanding, basic (in shares)	33,050,319	31,293,312
Weighted-average common shares outstanding, diluted (in shares)	33,050,319	31,293,312
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.20)	$ (3.02)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.20)	$ (3.02)

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

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+ Details

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation

Principles of Consolidation

The accompanying consolidated financial statements include those of the Company and its wholly-owned subsidiary. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

Segment Information

Revenue Recognition

Concentrations of Credit Risk and Off-Balance Sheet Risk

The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign-hedging arrangements.

Cash, Cash Equivalents, and Restricted Cash


	December 31, 2023		December 31, 2022
Cash and cash equivalents	$	67,602	$	45,157
Restricted cash	3,950		3,950
Total cash, cash equivalents and restricted cash	$	71,552	$	49,107

Marketable Securities

Fair Value Measurements

As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tiered value hierarchy that distinguishes between the following:

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

Property and Equipment

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


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Computer equipment			3 years
Leasehold improvements			Lesser of estimated useful life or remaining lease term

Leases

Impairment of Long-Lived Assets

Deferred Offering Costs

Contingencies

Indemnification Agreements

Research and Development Expenses

Patent Costs

Stock-Based Compensation

Subsequent to the Company’s IPO, the fair value of the common stock underlying the stock-based awards is the closing price of the Company’s common stock on the date of grant.

Income Taxes

Net Loss per Share

Comprehensive Loss

Emerging Growth Company Status

The Company qualifies as an “emerging growth company” (EGC), as defined in the Jumpstart Our Business Startups Act (JOBS Act) and may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not EGCs. The Company may take advantage of these exemptions until it is

no longer an EGC under Section 107 of the JOBS Act, which provides that an EGC can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to avail itself of the extended transition period and, therefore, while the Company is an EGC it will not be subject to new or revised accounting standards the same time that they become applicable to other public companies that are not EGCs, unless it chooses to early adopt a new or revised accounting standard. As a result of this election, the consolidated financial statements may not be comparable to companies that comply with public company FASB standards’ effective dates.

Recently Adopted Accounting Pronouncements

ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326)

ASU No. 2022-03, Fair Value Measurement (Topic 820)

Recently Issued Accounting Pronouncements

Leases - Maturities of Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Maturity of Lease Liability
2024	$ 13,084
2025	13,161
2026	8,826
2027	9,083
2028	9,349
Lessee, Operating Lease, Liability, to be Paid, After Year Four	41,091
Total lease payments	94,594
Less: imputed interest	(26,364)
Present value of operating lease liabilities	$ 68,230

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases

The Company’s operating lease activity is comprised of non-cancelable facility leases for office and laboratory space in Boston, Massachusetts.

IDB Lease

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 81,229 square feet of office and laboratory space (Premises) in Boston, Massachusetts. 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 81,229 square feet leased.

The accounting commencement date occurred in April 2023 when both the Landlord's build-out and the tenant improvements were substantially completed. On the accounting commencement date, the Company recorded an operating lease right-of-use (ROU) asset of $77.6 million and a total lease liability of $63.6 million.

The IDB Lease has a term 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 have not been included in the initial calculation of the Company's ROU asset upon lease commencement.

Under the terms of the IDB Lease, the Landlord provided an allowance of $19.5 million toward the cost of completing tenant improvements for the Premises. In addition, the Landlord provided an additional contribution of $1.6 million toward the cost of tenant improvements to the Premises, which amount shall be repaid by the Company over the term of the IDB Lease. Such repayments are included in the maturity of the lease liability table below. As of December 31, 2023, the Company had received the full tenant improvement allowance from the Landlord.

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. Accordingly, the $13.9 million of costs incurred by the Company related to the tenant improvements in excess of the Landlord's allowance were reclassified from other non-current assets to right-of-use assets upon commencement of the IDB lease and will be recognized as rent expense over the remaining lease term.

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 $4.0 million of cash collateralizing the letter of credit is classified as restricted cash on the Company's consolidated balance sheets.

6 Tide Street Lease

The Company entered into an operating lease for office and laboratory space at 6 Tide Street in Boston, Massachusetts in February 2020, and entered into subsequent amendments through 2021 to lease additional space (6 Tide Street Lease). Such amendments run co-terminus with the original lease.

During 2023, the Company entered into amendments to the 6 Tide Street lease pursuant to which the Company surrendered portions of the leased space in exchange for being relieved of its obligation to make lease payments. Upon the lease modification, the Company reassessed its incremental borrowing rate and remeasured the lease liability and right-of-use asset. Subsequent to the amendment, the Company continues to classify the 6 Tide Street Lease as an operating lease.

As of December 31, 2023, the Company had a total of 23,189 square feet licensed at this facility. The term for the remaining leased space will end on November 30, 2025. The fixed rental payment will be approximately $0.5 million per month for the remainder of the lease term. The Company has the option to extend the remaining leased space for a period of 3 years, or terminate such remaining space leased without penalty provided sufficient notice is given. At the adoption of ASC 842, the Company concluded that it is not reasonably certain that it will exercise its option to terminate the lease early or exercise its option to extend the leased space.

As of December 31, 2023, the Company's security deposit for the 6 Tide Street Lease was $0.7 million, of which, $0.3 million is recorded as a component of other current assets as it is expected to be received with one year of the balance sheet date. The remaining $0.4 million is recorded as a component of other non-current assets.

Summary of all lease costs recognized under ASC 842

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


	Year ended December 31, 2023
Operating lease cost	$	16,395
Variable lease cost	—
Total lease cost	$	16,395

Supplemental information related to all operating leases was as follows:


Other information	Year ended December 31, 2023
Operating cash flows used for operating leases (in thousands)	$	16,268
Weighted average remaining lease term	8.2 years
Weighted average discount rate	8.13%

Future payments due under all operating leases as of December 31, 2023 were as follows (in thousands):


Maturity of lease liabilities	Amount
2024	13,084
2025	13,161
2026	8,826
2027	9,083
2028	9,349
Thereafter	41,091
Total lease payments	$	94,594
Less: imputed interest	(26,364)
Present value of operating lease liabilities	$	68,230

IDB Sublease

In December 2022, the Company entered into a sublease agreement to sublease a portion of the office and laboratory space leased under the IDB Lease to a third-party (subtenant). The sublease term is 3 years and the subtenant has an option to extend the lease term for 6 months. The initial fixed rental rate is $0.2 million per month, and will increase 3% per annum thereafter. The sublessee is obligated to pay its ratable portion of operating expenses during the sublease term. The Company received a letter of credit of $0.5 million in place of a security deposit. As of December 31, 2023, no amounts have been drawn on the letter of credit.

The sublease accounting commencement date occurred in April 2023. During the year ended December 31, 2023, the Company recognized $1.5 million of sublease income. Such amount is recorded as a reduction to rent expense.

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net loss	$ (6,685)	$ (94,616)

- Definition

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

+ References

+ Details

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Marketable securities:	$ 284,367	$ 143,555
Cash	500	300
Fair Value, Recurring
Assets:
Total	351,469	188,462
Fair Value, Recurring \| U.S. government agency securities and treasuries
Assets:
Marketable securities:	251,168	99,396
Fair Value, Recurring \| Corporate debt securities
Assets:
Marketable securities:	33,199	44,159
Fair Value, Recurring \| Money market funds
Assets:
Cash equivalents	67,102	44,907
Fair Value, Recurring \| Level 1
Assets:
Total	67,102	44,907
Fair Value, Recurring \| Level 1 \| U.S. government agency securities and treasuries
Assets:
Marketable securities:	0	0
Fair Value, Recurring \| Level 1 \| Corporate debt securities
Assets:
Marketable securities:	0	0
Fair Value, Recurring \| Level 1 \| Money market funds
Assets:
Cash equivalents	67,102	44,907
Fair Value, Recurring \| Level 2
Assets:
Total	284,367	143,555
Fair Value, Recurring \| Level 2 \| U.S. government agency securities and treasuries
Assets:
Marketable securities:	251,168	99,396
Fair Value, Recurring \| Level 2 \| Corporate debt securities
Assets:
Marketable securities:	33,199	44,159
Fair Value, Recurring \| Level 2 \| Money market funds
Assets:
Cash equivalents	0	0
Fair Value, Recurring \| Level 3
Assets:
Total	0	0
Fair Value, Recurring \| Level 3 \| U.S. government agency securities and treasuries
Assets:
Marketable securities:	0	0
Fair Value, Recurring \| Level 3 \| Corporate debt securities
Assets:
Marketable securities:	0	0
Fair Value, Recurring \| Level 3 \| Money market funds
Assets:
Cash equivalents	$ 0	$ 0

Leases - Components of Lease Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Leases [Abstract]
Operating lease cost	$ 16,395
Variable lease cost	0
Total lease cost	$ 16,395

Stock Based Compensation

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock Based Compensation

Stock-Based Compensation

2021 Plan

In September 2021 the Company’s board of directors adopted, and in October 2021 the Company’s stockholders approved, the 2021 Plan, which became effective as of the date immediately prior to the date of the effectiveness of the registration statement for the IPO. The 2021 Plan allows the board of directors to grant incentive stock options or non-qualified stock options, restricted stock, restricted stock units and other equity awards to the Company’s officers, employees, directors and other key persons. In addition, the 2021 Plan includes a provision that allows for an automatic annual increase of 4% in the number of shares of common stock available for issuance under the 2021 Plan. Upon the adoption of the 2021 Plan, the Company ceased granting awards under the 2016 Plan. The total number of shares of common stock authorized for issuance under the 2021 Plan as of December 31, 2023 was 6,336,068 shares and was 5,262,917 shares as of December 31, 2022.

As of December 31, 2023, the Company had issued stock options and restricted stock units (RSUs) under the 2021 Plan. Both stock options and RSUs issued are comprised of service-based awards granted to employees. Vesting of stock options is subject to the recipient’s continued employment or service. Stock options and RSUs typically vest over a four-year period.

2016 Plan

Prior to the adoption of the 2021 Plan, the 2016 Plan provided for the Company to grant incentive stock options or non-qualified stock options, restricted stock, restricted stock units and other equity awards to employees, directors and consultants of the Company. The 2016 Plan was administered by the board of directors of the Company or, at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions were determined at the discretion of the board of directors, or its committee if so delegated. The 2016 Plan allows for early exercise of all stock option grants if authorized by the board of directors at the time of grant. The shares of common stock issued from the early exercise of stock options are restricted and continue to vest over the original service based vesting condition of the original stock option award. The Company has the option to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination.

The 2016 Plan will continue to govern the outstanding equity awards granted thereunder. The total number of shares of common stock authorized for issuance under the 2016 Plan as of December 31, 2023 and 2022 was 2,044,585 shares and 2,206,655 shares, respectively. As of both dates, all shares of common stock authorized for issuance under the 2016 Plan relate to outstanding stock options.

2021 Employee Stock Purchase Plan

In September 2021, the Company’s board of directors adopted, and in October 2021 the Company’s stockholders approved, the ESPP, which became effective as of the date immediately prior to the date of the effectiveness of the registration statement for the IPO. The ESPP is administered by the person or persons appointed by the Company’s board of directors for such purpose. The ESPP initially provided participating employees with the opportunity to purchase up to an aggregate of 278,762 shares of common stock. The number of shares of common stock reserved for issuance under the ESPP will automatically increase on January 1st of each year beginning in 2022 and continuing through and including 2031 by the lesser of (i) 1% of the outstanding number of shares of our common stock of the immediately preceding December 31, (ii) 557,524 shares or (iii) such number of shares as determined by the ESPP administrator. The total number of shares of common stock authorized for issuance under the 2021 ESPP as of December 31, 2023 and 2022 was 839,539 shares and 563,115 shares, respectively.

Compensation expense for discounted purchases under the 2021 ESPP is measured using the Black-Scholes model to compute the fair value of the lookback provision plus the purchase discount and is recognized as compensation expense over the course of the offering period.

Stock-Based Compensation

The Company recognized stock-based compensation expense in the consolidated statements of operations and comprehensive loss, by award type, as follows (in thousands):


	Year ended December 31,
	2023		2022
Stock Options	$	9,887	$	8,648
Restricted Stock Units	3,015		1,106
ESPP	209		141
Total	$	13,111	$	9,895


	Year ended December 31,
	2023		2022
Research and development expenses	$	6,169	$	4,166
General and administrative expenses	6,942		5,729
Total	$	13,111	$	9,895

Stock Option Valuation


	December 31, 2023	December 31, 2022
Risk‑free interest rate	4.09%	2.20%
Expected volatility	72%	71%
Expected dividend yield	—	—
Expected term (in years)	6.01	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 14,745 and 53,741 unvested shares related to early exercises of stock options as of December 31, 2023 and December 31, 2022, respectively. In the years ended December 31, 2023 and 2022, the liability associated with the unvested early exercise of stock options was $0.1 million and $0.2 million, respectively.

Stock Options

The following table summarizes the Company’s stock option activity since December 31, 2022:


	Number of Shares	Weighted‑Average Exercise Price		Weighted‑Average Remaining Contractual Term	Aggregate Intrinsic Value(2)
				(in years)	(in thousands)
Outstanding as of December 31, 2022	5,028,850	$	10.95
Granted	799,144	13.85
Exercised	(214,078)	5.54
Forfeited	(199,556)	15.63
Outstanding as of December 31, 2023	5,414,360	$	11.42	7.78	$	25,569
Exercisable as of December 31, 2023(1)	3,297,593	$	9.49	7.26	$	21,529

(1)This represents the number of vested and unvested options exercisable as of December 31, 2023.

The aggregate intrinsic value of stock options exercised during the years ended December 31, 2023 and 2022 was $2.1 million and $1.0 million, while the company received $1.2 million and $0.2 million in proceeds for the exercise of these options, respectively.

The weighted-average grant-date fair value of stock options granted during the years ended December 31, 2023 and 2022 was $9.23 per share and $7.51 per share, respectively. As of December 31, 2023, there was $20.7 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 year ended December 31, 2023, 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. For the majority of RSUs, the restricted stock vests over a four-year period, with 25% of the shares vesting on each anniversary of the grant date.

A summary of restricted stock activity during the year ended December 31, 2023 is as follows:


	Shares	Weighted‑ Average Grant‑Date Fair Value
Unvested as of December 31, 2022	463,964	$	12.26
Issued	990,167	14.29
Vested	(138,361)	12.30
Forfeited	(47,309)	12.51
Unvested as of December 31, 2023	1,268,461	$	13.83

As of December 31, 2023, there was $15.1 million of unrecognized stock-based compensation expense related to unvested RSUs, which is expected to be recognized over a weighted-average remaining vesting period of 3.17 years.

Income Taxes - Schedule of Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Current:
Federal	$ 14,962	$ 0
State	3,779	0
Foreign	0	0
Total current tax provision	18,741	0
Deferred:
Federal	0	0
State	0	0
Foreign	0	0
Total deferred tax provision	0	0
Total income tax provision	$ 18,741	$ 0

Net Loss per Share - Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	6,697,566	5,546,555
Unvested restricted common stock
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	1,268,461	463,964
Unvested shares from early exercises
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	14,745	53,741
Stock Options
Net Loss per Share
Antidilutive securities excluded from common stock (in shares)	5,414,360	5,028,850

Collaboration and License Agreements (Tables)

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table summarizes the revenue recognized in connection with the Company's performance under the Vertex Agreement during the year ended December 31, 2023.


	Year ended December 31,
	2023		2022
Collaboration services revenue	$	17,508	$	—
Recognition of upfront and milestone payments	111,505		—
Total	$	129,013	$	—

Stock-Based Compensation - Restricted Stock Awards (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Shares
Unvested balance, at beginning of period (in shares) \| shares	463,964
Issued (in shares) \| shares	990,167
Vested (in shares) \| shares	(138,361)
Forfeited (in shares) \| shares	(47,309)
Unvested balance, at end of period (in shares) \| shares	1,268,461
Weighted‑ Average Grant‑Date Fair Value
Unvested balance at beginning of period (in dollars per share) \| $ / shares	$ 12.26
Issued (in dollars per share) \| $ / shares	14.29
Vested (in dollars per share) \| $ / shares	12.30
Forfeited (in dollars per share) \| $ / shares	12.51
Unvested balance at end of period (in dollars per share) \| $ / shares	$ 13.83

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsFor the year ended December 31, 2023, subsequent events were evaluated through the date on which these consolidated financial statements were issued to determine if such events should be reflected in these consolidated financial statements.

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 67,602	$ 45,157
Marketable securities	284,367	143,555
Collaboration receivable	5,878	0
Prepaid expenses and other current assets	11,924	21,163
Total current assets	369,771	209,875
Property and equipment, net	11,191	7,681
Restricted cash	3,950	3,950
Right-of-use assets, operating leases	81,490	25,340
Other non-current assets	2,790	5,210
Total assets	469,192	252,056
Current liabilities:
Accounts payable	3,277	5,990
Accrued expenses and other current liabilities	11,325	7,576
Income taxes payable	4,024	0
Operating lease obligations, current portion	7,909	8,406
Deferred revenue, current portion	132,261	0
Total current liabilities	158,796	21,972
Operating lease obligations, net of current portion	60,321	17,530
Deferred revenue, net of current portion	7,715	0
Total liabilities	226,832	39,502
Commitments and contingencies (Note 10)
Stockholders’ equity:
Common stock, par value $0.0001; 150,000,000 shares authorized; 33,461,771 shares issued and 33,437,296 shares outstanding as of December 31, 2023 and 31,448,508 shares issued and 31,394,767 shares outstanding as of December 31, 2022	3	3
Additional paid‑in capital	437,132	402,893
Accumulated other comprehensive income (loss)	195	(2,057)
Accumulated deficit	(194,970)	(188,285)
Total stockholders’ equity	242,360	212,554
Total liabilities and stockholders’ equity	$ 469,192	$ 252,056

Cover Page - USD ($) $ in Millions	12 Months Ended
Cover Page - USD ($) $ in Millions	Dec. 31, 2023	Mar. 06, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
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	One Design Center Place
Entity Address, Address Line Two	Suite 17-500
Entity Address, State or Province	MA
Entity Address, City or Town	Boston
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 Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 431.2
Entity Common Stock, Shares Outstanding		33,601,103
Documents Incorporated by Reference	Portions of the registrant's definitive Proxy Statement for its 2024 Annual Meeting of Stockholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant's fiscal year ended December 31, 2023, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Entity Central Index Key	0001689375
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

Nature of the Business (Details) - USD ($) $ in Thousands	12 Months Ended
Nature of the Business (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net loss	$ 6,685	$ 94,616
Accumulated deficit	(194,970)	$ (188,285)
Cash and cash equivalents	$ 352,000

- Definition

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

+ References

+ Details

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Property and Equipment, Net

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

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


	2023		2022
Laboratory equipment	$	12,596	$	8,335
Furniture and fixtures	2,228		161
Computer equipment	431		43
Leasehold improvements	1,859		1,859
Construction in progress	—		584
Total property and equipment	17,114		10,982
Less: accumulated depreciation	(5,923)		(3,301)
Property and equipment, net	$	11,191	$	7,681

Depreciation expense for the years ended December 31, 2023 and 2022 was $2.8 million and $1.9 million, respectively.

Stock Based Compensation - Stock Option Valuation (Details) - Stock Options	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Assumptions used to determine the fair value of stock options granted
Risk-free interest rate (as percentage)	4.09%	2.20%
Expected volatility (as percentage)	72.00%	71.00%
Expected dividend yield (as percentage)	0.00%	0.00%
Expected term (in years)	6 years 3 days	6 years 14 days

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of Debt Securities, Available-for-sale

The following is a summary of the Company's marketable securities at December 31, 2023 and December 31, 2022 (in thousands).


	As of December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. government agency securities and treasuries	$	235,500	$	127	$	(41)	$	235,586
Corporate debt securities	25,466		—		(29)		25,437
Total securities with a maturity of one year or less	$	260,966	$	127	$	(70)	$	261,023

U.S. government agency securities and treasuries	15,537		45		—		15,582
Corporate debt securities	7,669		93		—		7,762
Total securities with a maturity of greater than one year	$	23,206	$	138	$	—	$	23,344
Total available-for-sale securities	$	284,172	$	265	$	(70)	$	284,367


	As of December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. government agency securities and treasuries	$	100,555	$	—	$	(1,159)	$	99,396
Corporate debt securities	41,615		—		(774)		40,841
Total securities with a maturity of one year or less	$	142,170	$	—	$	(1,933)	$	140,237

U.S. government agency securities and treasuries	—		—		—		—
Corporate debt securities	3,442		—		(124)		3,318
Total securities with a maturity of greater than one year	$	3,442	$	—	$	(124)	$	3,318
Total available-for-sale securities	$	145,612	$	—	$	(2,057)	$	143,555

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid‑in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2021		31,224,336
Beginning balance 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)		84,526
Issuance of common stock upon exercise of stock options	$ 195		195
Vesting of early exercised options (in shares)	53,741	58,015
Vesting of early exercised options	$ 135		135
Purchase of common stock under the employee stock purchase plan (in shares)		27,890
Purchase of common stock under the employee stock purchase plan	284		284
Stock‑based compensation	9,895		9,895
Other comprehensive income (loss)	(2,057)			(2,057)
Net loss	$ (94,616)				(94,616)
Ending balance (in shares) at Dec. 31, 2022	31,394,767	31,394,767
Ending balance at Dec. 31, 2022	$ 212,554	$ 3	402,893	(2,057)	(188,285)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	214,078	214,078
Issuance of common stock upon exercise of stock options	$ 1,187		1,187
Issuance of common stock in connection with the Vertex Agreement (in shares)		1,618,613
Issuance of common stock in connection with the Vertex Agreement	$ 19,407		19,407
Vesting of early exercised options (in shares)	14,745	33,416
Vesting of early exercised options	$ 91		91
Vesting of restricted stock units (in shares)		138,361
Purchase of common stock under the employee stock purchase plan (in shares)		38,061
Purchase of common stock under the employee stock purchase plan	443		443
Stock‑based compensation	13,111		13,111
Other comprehensive income (loss)	2,252			2,252
Net loss	$ (6,685)				(6,685)
Ending balance (in shares) at Dec. 31, 2023	33,437,296	33,437,296
Ending balance at Dec. 31, 2023	$ 242,360	$ 3	$ 437,132	$ 195	$ (194,970)

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

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


	Fair Value Measurements at December 31, 2023
	Level 1		Level 2		Level 3		Total
Cash equivalents:(1)
Money market funds	$	67,102	$	—	$	—	$	67,102
Marketable securities:
U.S. government agency securities and treasuries	—		251,168		—		251,168
Corporate debt securities	—		33,199		—		33,199
Total	$	67,102	$	284,367	$	—	$	351,469


	Fair Value Measurements at December 31, 2022
	Level 1		Level 2		Level 3		Total
Cash equivalents: (1)
Money market funds	$	44,907	$	—	$	—	$	44,907
Marketable securities:
U.S. government agency securities and treasuries	$	—	$	99,396	$	—	$	99,396
Corporate debt securities	—		44,159		—		44,159
Total	$	44,907	$	143,555	$	—	$	188,462

(1)The cash equivalent amounts above do not include $0.5 million and $0.3 million of cash related to checking accounts included in cash and cash equivalents as of December 31, 2023 and December 31, 2022. 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

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of 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):


	December 31, 2023		December 31, 2022
Cash and cash equivalents	$	67,602	$	45,157
Restricted cash	3,950		3,950
Total cash, cash equivalents and restricted cash	$	71,552	$	49,107

Schedule of Cash and Cash Equivalents


	December 31, 2023		December 31, 2022
Cash and cash equivalents	$	67,602	$	45,157
Restricted cash	3,950		3,950
Total cash, cash equivalents and restricted cash	$	71,552	$	49,107

Schedule of Estimated Useful Life

Depreciation expense is recognized using the straight line method over the estimated useful life of each asset as follows:


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Computer equipment			3 years
Leasehold improvements			Lesser of estimated useful life or remaining lease term

Leases - Cash flow information (Details) $ in Thousands	12 Months Ended
Leases - Cash flow information (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 16,268
Weighted average remaining lease term	8 years 2 months 12 days
Weighted average discount rate	8.13%

Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 17,114	$ 10,982
Less: accumulated depreciation	(5,923)	(3,301)
Property and equipment, net	11,191	7,681
Depreciation expense	2,841	1,895
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	12,596	8,335
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	2,228	161
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	431	43
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	1,859	1,859
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 0	$ 584

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis


	Fair Value Measurements at December 31, 2023
	Level 1		Level 2		Level 3		Total
Cash equivalents:(1)
Money market funds	$	67,102	$	—	$	—	$	67,102
Marketable securities:
U.S. government agency securities and treasuries	—		251,168		—		251,168
Corporate debt securities	—		33,199		—		33,199
Total	$	67,102	$	284,367	$	—	$	351,469


	Fair Value Measurements at December 31, 2022
	Level 1		Level 2		Level 3		Total
Cash equivalents: (1)
Money market funds	$	44,907	$	—	$	—	$	44,907
Marketable securities:
U.S. government agency securities and treasuries	$	—	$	99,396	$	—	$	99,396
Corporate debt securities	—		44,159		—		44,159
Total	$	44,907	$	143,555	$	—	$	188,462

Collaboration and License Agreements

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Collaboration and License Agreements

Vertex Agreement - Overview

The Company and Vertex closed the Vertex Agreement in February 2023, as amended in October 2023, pursuant to which the Company granted Vertex an exclusive worldwide license to research, develop, manufacture and commercialize VX-670, as well as any additional EEV-based therapeutic candidates that may be identified by the Company for the potential treatment of myotonic dystrophy type 1 (DM1) in the course of the parties’ global research collaboration. In October 2023, the Company and Vertex amended the Strategic Collaboration and License Agreement to clarify a milestone and related payment terms.

The Vertex Agreement provides for a four-year global research collaboration under which Entrada will continue to perform preclinical development of the Company's partnered candidate VX-670 pursuant to the mutually agreed-upon research plan (Research Plan). The Research Plan is overseen by a Joint Research Committee (JRC) as detailed in the Vertex Agreement. Pursuant to the terms of the Vertex Agreement, the JRC may amend the Research Plan to include additional DM1-related research activities with a goal of identifying other EEV-based therapeutic product candidates for the potential treatment of DM1. Vertex is obligated to reimburse the Company’s research expenses incurred in performing activities under the Research Plan.

Pursuant to the Vertex Agreement, the Company received an upfront payment of $223.7 million, and Vertex made an equity investment of $26.3 million by purchasing 1,618,613 shares of the Company's common stock, pursuant to a separate but simultaneously executed stock purchase agreement. Under the terms of the Vertex Agreement, the Company is eligible to receive up to $485.0 million upon the achievement of certain research, development, regulatory and commercial milestones. The Company will also receive tiered royalties, from the mid to high single digits based on potential future net sales of licensed products as set forth in the Vertex Agreement. In October 2023, the Company achieved a milestone pursuant to the Vertex Agreement related to preclinical IND-enabling GLP toxicology studies of VX-670 that triggered a $17.5 million milestone payment, which the Company received in November 2023.

The term of the Vertex Agreement will expire in its entirety upon expiration of the royalty term as set forth in the Vertex Agreement. Vertex may terminate the Vertex Agreement for convenience by providing adequate written notice to the Company. The Company may terminate the Vertex Agreement under certain specified circumstances, including in the event Vertex or any of its affiliates or sublicensees challenges directly or indirectly in a legal or administrative proceeding the patentability, enforceability, or validity of any licensed patent as set forth in the Vertex Agreement. Either party may

terminate the Vertex Agreement for an uncured material breach by the other party or upon the bankruptcy or insolvency of the other party. Neither party may assign the agreement without the prior written consent of the other party, except that a party may assign its rights and obligations to an affiliate or third party that acquires all or substantially all of the business or assets to which the Vertex Agreement relates and agrees in writing to be bound by the terms of the Vertex Agreement.

Vertex Agreement - Accounting Analysis

The Company determined that the Vertex Agreement should be accounted for in accordance with ASC 606 as Vertex was deemed to be a customer. The Company assessed the promised goods and services under the Vertex Agreement in accordance with ASC 606. At inception, the Vertex Agreement included one performance obligation which was the combination of the exclusive license and the performance of the research activities for VX-670 (Performance Obligation One). The Company concluded that the license is not distinct from the research and development services for VX-670 during the research collaboration as Vertex cannot fully exploit the value of the license without receipt of such services. The Company also determined, at inception, that Vertex's ability to engage Entrada to perform work on additional EEV-based therapeutic candidates for the potential treatment of DM1 through the JRC represented customer options. The Company concluded that these customer options do not represent a material right as these services will be reimbursed by Vertex at a price that represents standalone selling price for such services.

In the second quarter of 2023, pursuant to the terms of the agreement, Vertex amended the Research Plan (The Amended Research Plan) to engage Entrada to perform work on additional EEV-based therapeutic candidates for the potential treatment of DM1 (Performance Obligation Two). Such work is treated as a separate contract for accounting purposes and represents a separate performance obligation as the activities are distinct from the combined license and research activities for VX-670.

Determination of Transaction Price

At the commencement of the arrangement, the Vertex Agreement had a fixed transaction price of $232.0 million, primarily consisting of the $223.7 million upfront fee plus a premium of $6.9 million related to the 1,618,613 shares sold to Vertex under the Stock Purchase Agreement when measured at fair value on the date of issuance. The shares issued to Vertex pursuant to the Stock Purchase Agreement were unregistered and therefore considered restricted securities at the time of issuance. As a result, the fair value of the shares issued to Vertex of $19.4 million was calculated using the closing price of the Company's unrestricted common shares on February 8, 2023, adjusted to reflect a discount for lack of marketability (DLOM) due to the shares issued being unregistered and therefore subject to related sale restrictions.

The Company is also entitled to reimbursement of costs incurred in connection with the delivery of services performed for VX-670 and for additional EEV-based therapeutic candidates under the Amended Research Plan. The Company utilized the most likely amount approach to estimate the expected cost reimbursement. The Company concluded that these amounts do not require a constraint and are included in the transaction price at inception. The Company considers this estimate at each reporting date and updates the estimate based on information available.

In October 2023, the Company achieved a milestone related to preclinical IND-enabling GLP toxicology studies of VX-670, which triggered a $17.5 million payment that was received in November 2023. Upon the achievement of the milestone, the Company recorded a $7.8 million cumulative catch-up entry to collaboration revenue. No additional milestones were deemed probable of being achieved as of December 31, 2023 and, therefore, all remaining milestone payments were fully constrained and excluded from the transaction price as of December 31, 2023. The Company re-evaluates the probability of achievement of development milestones and any related constraint at each period end, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenue in the period of adjustment.

Allocation and Recognition

As of December 31, 2023, the transaction price for the combination of the exclusive license and the performance of the research activities for VX-670 consists of (i) the upfront payment, (ii) the milestone achieved in October 2023 and (iii) reimbursement of costs incurred in connection with the delivery of services under the Amended Research Plan associated with VX-670. The transaction price for the work on additional EEV-based therapeutic candidates consists of the reimbursement of costs incurred in connection with the delivery of services under the Amended Research Plan associated with such work.

The Company recognizes revenue associated with both performance obligations as the related research and development services are provided using an input method, according to the costs incurred as related to the respective

research services and the costs expected to be incurred in the future to satisfy the performance obligations in accordance with the Amended Research Plan. The transfer of control occurs over this time period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligations. The estimated costs associated with the remaining effort required to complete the performance obligations in accordance with the research plans may change, which may materially impact revenue recognition. The Company regularly evaluates and, when necessary, updates the costs associated with the remaining effort pursuant to the performance obligations under the Vertex Agreement and records any necessary adjustment to revenue for the change in estimate.

The amounts received that have not yet been recognized as revenue are deferred on the Company’s consolidated balance sheet and will be recognized over the remaining research and development period until the performance obligation is satisfied. The performance obligations have not been fully satisfied as of December 31, 2023.

The following table summarizes the revenue recognized in connection with the Company's performance under the Vertex Agreement during the year ended December 31, 2023.


	Year ended December 31,
	2023		2022
Collaboration services revenue	$	17,508	$	—
Recognition of upfront and milestone payments	111,505		—
Total	$	129,013	$	—

The aggregate amount of the transaction price allocated to the Company’s unsatisfied performance obligations and recorded in deferred revenue at December 31, 2023 is $139.0 million. The Company will recognize the deferred revenue related to the research and development services based on a cost input method, over the remaining term of the research plan.

The costs incurred to perform the research activities pursuant to the Vertex Agreement are recorded in research and development expenses.

Pierrepont Agreement

In July 2023, the Company and Pierrepont Therapeutics, Inc. (Pierrepont) entered into a license agreement (the Pierrepont Agreement) to advance the development of ENTR-501, the Company’s intracellular thymidine phosphorylase enzyme replacement therapy in development for the treatment of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). The Company recognized no revenue related to this agreement for the year ended December 31, 2023 as the underlying performance obligations had not been delivered as of December 31, 2023.

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued Expenses and Other Current Liabilities
Employee compensation and benefits	$ 6,660	$ 5,063
External research and development expenses	2,894	1,157
General and administrative professional service expenses	767	925
Other	1,004	431
Total accrued expenses and other current liabilities	$ 11,325	$ 7,576

Common Stock and Preferred Stock - Schedule of Shares Reserved for Future Issuance under Equity Compensation Plans (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Class of Stock
Total shares of authorized common stock reserved for future issuance (in shares)	9,220,192	8,032,687
2021 Plan [Member]
Class of Stock
Total shares of authorized common stock reserved for future issuance (in shares)	1,697,832	1,976,758
Employee Stock Option
Class of Stock
Total shares of authorized common stock reserved for future issuance (in shares)	5,414,360	5,028,850
Restricted Stock
Class of Stock
Total shares of authorized common stock reserved for future issuance (in shares)	1,268,461	463,964
Employee Stock
Class of Stock
Total shares of authorized common stock reserved for future issuance (in shares)	839,539	563,115

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482987/272-10-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27)(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

+ Details

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

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


	2023		2022
Laboratory equipment	$	12,596	$	8,335
Furniture and fixtures	2,228		161
Computer equipment	431		43
Leasehold improvements	1,859		1,859
Construction in progress	—		584
Total property and equipment	17,114		10,982
Less: accumulated depreciation	(5,923)		(3,301)
Property and equipment, net	$	11,191	$	7,681

Summary of Significant Accounting Policies - Property and Equipment (Details)	Dec. 31, 2023
Laboratory equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Accrued Expenses and Other Current Liabilities

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following at December 31 (in thousands):


	2023		2022
Employee compensation and benefits	$	6,660	$	5,063
External research and development expenses	2,894		1,157
General and administrative professional service expenses	767		925
Other	1,004		431
Total accrued expenses and other current liabilities	$	11,325	$	7,576

Common Stock and Preferred Stock - Additional Information (Details) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Sep. 30, 2023 USD ($)	Feb. 28, 2023 USD ($) $ / shares shares	Dec. 31, 2023 vote $ / shares shares	Dec. 31, 2022 $ / shares shares
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) \| $ / shares			$ 0.0001	$ 0.0001
Number of votes \| vote			1
Preferred stock, shares authorized (in shares)			10,000,000	10,000,000
Preferred stock, par value (in dollars per share) \| $ / shares			$ 0.0001	$ 0.0001
Preferred stock shares issued (in shares)			0	0
Preferred stock shares outstanding (in shares)			0	0
Vertex Agreement
Class of Stock
Number of shares purchases in equity investment (in shares)		1,618,613
Net proceeds from issuance of common stock \| $		$ 26.3
Offering price per share (in dollars per share) \| $ / shares		$ 16.26
Sales Agreement
Class of Stock
Number of shares purchases in equity investment (in shares)			0
Sales Agreement \| Maximum
Class of Stock
Net proceeds from issuance of common stock \| $	$ 150.0

Summary of Significant Accounting Policies - Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Cash and cash equivalents	$ 67,602	$ 45,157
Restricted cash	3,950	3,950
Total cash, cash equivalents and restricted cash	$ 71,552	$ 49,107	$ 291,064

Collaboration and License Agreements - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Oct. 31, 2023	Feb. 28, 2023	Dec. 31, 2023
Vertex
Commitments and Contingencies
Vertex agreement, term		4 years
Milestone payment	$ 17.5
Shares issued		$ 19.4
Cumulative catch-up adjustment		7.8
Vertex \| Private Placement
Commitments and Contingencies
Net proceeds from issuance of common stock		$ 26.3
Number of shares purchases in equity investment (in shares)		1,618,613
Consideration amount		$ 485.0
Vertex \| License
Commitments and Contingencies
Up-front payment		223.7
Revenue, remaining performance obligation, amount		232.0	$ 139.0
Premium		$ 6.9
Pierrepont Therapeutics, Inc
Commitments and Contingencies
Revenue recognized			$ 0.0