TScan Therapeutics (TCRX) 10-K 6 Mar 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Mar. 01, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	TCRX
Entity Registrant Name	TScan Therapeutics, Inc.
Entity Central Index Key	0001783328
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Document Annual Report	true
Document Transition Report	false
Entity File Number	001-40603
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-5282075
Entity Address, Address Line One	830 Winter Street
Entity Address, State or Province	MA
Entity Address, City or Town	Waltham
Entity Address, Postal Zip Code	02451
City Area Code	857
Local Phone Number	399-9500
Title of 12(b) Security	Voting Common Stock, $0.0001 par value per share
Document Financial Statement Error Correction [Flag]	false
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Entity Public Float			$ 74,489,510
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	34
Documents Incorporated by Reference [Text Block]	DOCUMENTS INCORPORATED BY REFERENCE The registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2024 Annual Meeting of Stockholders within 120 days of the end of the registrant’s fiscal year ended December 31, 2023. Portions of such definitive proxy statement for the 2024 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.
Voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		43,605,608
Non-voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		4,276,588

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 133,359	$ 120,027
Marketable securities	58,685
Prepaid expenses and other current assets	2,193	4,100
Total current assets	194,237	124,127
Property and equipment, net	7,742	10,100
Right-of-use assets	63,492	59,102
Restricted cash	5,031	5,037
Long-term deposit and other assets	1,647	725
Total assets	272,149	199,091
Current liabilities:
Accounts payable	2,374	2,912
Accrued expenses and other current liabilities	10,716	6,838
Operating lease liability, current portion	3,246	3,681
Deferred revenue, current portion	10,137	3,874
Current portion of long-term debt	3,347
Total current liabilities	29,820	17,305
Deferred revenue, net of current portion	5,622
Operating lease liability, net of current portion	59,140	53,013
Long-term debt and accrued interest	26,700	29,290
Other long term liabilities		49
Total liabilities	121,282	99,657
Commitments and contingencies (Note 10)
Stockholders' equity (deficit):
Additional paid-in capital	398,459	257,810
Accumulated deficit	(247,597)	(158,379)
Total stockholders' equity	150,867	99,434
Total liabilities and stockholders' equity	272,149	199,091
Voting Common Stock
Stockholders' equity (deficit):
Common stock	4	2
Non-voting Common Stock
Stockholders' equity (deficit):
Common stock	$ 1	$ 1

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	43,552,941	19,082,820
Common stock, shares outstanding	43,552,941	19,082,820
Non-voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	4,276,588	5,143,134
Common stock, shares outstanding	4,276,588	5,143,134

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenue
Collaboration and license revenue	$ 21,049	$ 13,535
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]	Collaboration and license revenue	Collaboration and license revenue
Operating expenses:
Research and development	$ 88,153	$ 59,819
General and administrative	26,354	20,352
Total operating expenses	114,507	80,171
Loss from operations	(93,458)	(66,636)
Other (expense) income:
Interest and other income, net	7,999	1,591
Interest expense	(3,759)	(1,176)
Total other income	4,240	415
Net loss	$ (89,218)	$ (66,221)
Net loss per share, basic	$ (1.36)	$ (2.75)
Net loss per share, diluted	$ (1.36)	$ (2.75)
Weighted average common shares outstanding- basic	65,599,858	24,048,267
Weighted average common shares outstanding-diluted	65,599,858	24,048,267

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Voting Common Stock	Non-voting Common Stock	Common Stock Voting Common Stock	Common Stock Non-voting Common Stock	Additional Paid-In Capital	Accumulated Deficit
Balances at Dec. 31, 2021	$ 160,778			$ 2	$ 1	$ 252,933	$ (92,158)
Balances, shares at Dec. 31, 2021				18,764,463	5,143,134
Exercise of stock options	133					133
Exercise of stock options, shares				55,107
Issuance of common stock, net of offering cost/ ESPP plan	193					193
Issuance of common stock, net of offering cost/ ESPP plan, shares				146,380
Vesting of restricted common stock, shares				116,870
Stock-based compensation expense	4,551					4,551
Net loss	(66,221)						(66,221)
Balances at Dec. 31, 2022	99,434			$ 2	$ 1	257,810	(158,379)
Balances, shares at Dec. 31, 2022		19,082,820	5,143,134	19,082,820	5,143,134
Exercise of stock options	711					711
Exercise of stock options, shares				316,441
Issuance of common stock, net of offering cost/ ESPP plan	42,414			$ 2		42,412
Issuance of common stock, net of offering cost/ ESPP plan, shares				23,287,134
Issuance of pre-funded warrants, net of offering costs	92,318					92,318
Conversion of non-voting common stock to voting common stock, shares				866,546	(866,546)
Stock-based compensation expense	5,208					5,208
Net loss	(89,218)						(89,218)
Balances at Dec. 31, 2023	$ 150,867			$ 4	$ 1	$ 398,459	$ (247,597)
Balances, shares at Dec. 31, 2023		43,552,941	4,276,588	43,552,941	4,276,588

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (89,218)	$ (66,221)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	5,361	5,137
Accretion of marketable securities	(1,072)
Non-cash interest expense related to note payable	757	260
Stock-based compensation	5,208	4,551
Changes in current assets and liabilities:
Prepaid expenses and other assets	985	(410)
Right-of-use assets and lease liabilities, net	935	(2,047)
Accounts payable	(52)	528
Accrued expense and other liabilities	3,853	732
Deferred revenue	11,885	(9,033)
Net cash used in operating activities	(61,358)	(66,503)
Cash flows from investing activities:
Purchases of property and equipment	(3,146)	(4,225)
Purchases of marketable securities	(77,613)
Proceeds from maturities of marketable securities	20,000
Net cash used in investing activities	(60,759)	(4,225)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of offering costs	42,414
Proceeds from issuance of pre-funded warrants, net of offering costs	92,318
Issuance of common stock under ESPP plan		193
Proceeds from exercise of stock options	711	133
Proceeds from issuance of term loan, net of issuance costs paid to lender		29,354
Payments of debt issuance costs		(324)
Net cash provided by financing activities	135,443	29,356
Net increase (decrease) in cash, cash equivalents and restricted cash	13,326	(41,372)
Cash, cash equivalents, and restricted cash - beginning of year	125,064	166,436
Cash, cash equivalents, and restricted cash - end of year	138,390	125,064
Summary of cash, cash equivalents and restricted cash reported within the consolidated balance sheets:
Cash and cash equivalents	133,359	120,027
Restricted cash	5,031	5,037
Total cash, cash equivalents, and restricted cash	138,390	125,064
Supplemental disclosure of cash flow information:
Cash paid for interest	3,002	660
Supplemental disclosure of non-cash investing and financing activities:
Lease liability arising from obtaining right-of-use asset	6,214	53,541
Purchase of property and equipment in accounts payable and accrued liabilities	$ 301	$ 444

Nature of Business and Basis of

Nature of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	1. Nature of Business and Basis of Presentation Nature of Business TScan Therapeutics, Inc. (the Company) is a biotechnology company that was incorporated in Delaware on April 17, 2018 , and has a principal place of business in Waltham, Massachusetts. The Company is a biopharmaceutical company focused on developing a pipeline of T cell receptor-engineered T cell (TCR-T) therapies for the treatment of patients with cancer. Risks, Uncertainties and Going Concern The Company is subject to risks common to companies in the biotechnology industry, including, but not limited to, successful development of technology, obtaining additional funding, protection of proprietary technology, compliance with government regulations, risks of failure of preclinical studies, clinical studies and clinical trials, the need to obtain marketing approval for its product candidates and the ability to successfully market its therapies any products that receive approval, fluctuations in operating results, economic pressure impacting therapeutic pricing, dependence on key personnel, risks associated with changes in technologies, development by competitors of technological innovations and the ability to scale manufacturing to large scale production. Product candidates currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from therapy sales. The accompanying consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. The Company has primarily funded its operations with proceeds from sales of capital stock, including the IPO completed in July 2021, issuance of convertible debt in September 2022 and with payments received under its license and collaboration agreements. Since its inception, the Company has incurred recurring losses, including net losses of $ 89.2 million and $ 66.2 million for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, the Company had an accumulated deficit of $ 247.6 million. The Company expects to continue to generate operating losses in the foreseeable future. The Company expects that its cash and cash equivalents and marketable securities as of December 31, 2023 will be sufficient to fund the Company’s operations for at least the next twelve months from the date of the issuance of the financial statements. The Company will need to obtain substantial additional funding through equity offerings, debt financings, collaborations, strategic alliances and/or licensing arrangements in order to fund its research and development and ongoing operating expenses. The Company may not be able to obtain financing on acceptable terms, when needed or at all, and the Company may not be able to enter into collaborations, strategic alliances or licensing arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. Any collaborations, strategic alliances or licensing arrangements may require the Company to relinquish rights to certain of its technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to the Company. If the Company is unable to obtain funding, the Company could be forced to delay, limit, reduce or eliminate some or all of its research and development programs, pipeline expansion or future commercialization efforts or grant rights to develop and market product candidates, which could adversely affect its business prospects. Although management will continue to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations when needed or at all.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements reflect the operations of the Company and the Company’s wholly owned subsidiary, TScan Securities Corporation. The accompanying consolidated financial statements have been prepared in conformity with US GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative US GAAP as found in the Accounting Standards Codification, or ASC, and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB. Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of the consolidated financial statements in accordance with US GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. The Company bases its estimates on historical experience, known trends and other market-specific or relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Actual results may differ from those estimates or assumptions. Cash and Cash Equivalents Cash includes cash in readily available checking and money market accounts. Cash equivalents include all highly liquid investments maturing within 90 days from the date of purchase. The cash equivalents consisted of money market funds and government securities. Restricted Cash In connection with the Company’s facility lease agreements, the Company is required to provide letters of credit totaling of $ 5.0 million for the benefit of the landlords to serve as security deposits. As of December 31, 2023 and 2022 , the cash securing the letter of credit was classified as restricted cash (non-current) on the consolidated balance sheets. Marketable Securities The Company classifies all of its marketable securities as available-for-sale based upon its intent with regard to such investments. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income (loss). The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest and investment income. Realized gains and losses and declines in value judged to be other than temporary on available-for-sale securities, are included in interest and investment income. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest and investment income. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary. Concentrations of Credit Risk Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company’s cash deposits on hand at any one financial institution often exceed federally insured limits. The Company places its cash in financial institutions that management believes to be of high credit quality. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Property and Equipment Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the respective assets as follows: Estimated useful life Laboratory equipment 3 - 5 years Furniture and fixtures 3 - 5 years Office and computer equipment 3 - 5 years Software 3 - 5 years Leasehold improvements Shorter of the asset's estimated useful life or the remaining lease term Major additions and betterments are capitalized; expenditures for repairs and maintenance, which do not improve or extend the life of the respective assets, are charged to operating expense as incurred. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Impairment of Long-Lived Assets Long-lived assets to be held and used, including property and equipment, are tested for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be fully recoverable. Evaluation of the recoverability of the asset or asset group is based on an estimate of undiscounted future cash flows resulting from the use of the asset or asset group and its eventual disposition. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the asset or asset group, an impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value. The Company did not record any impairment losses on long-lived assets during the periods presented. Fair Value Measurements Certain assets and liabilities are carried at fair value under US GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the user of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1 —Unadjusted quoted prices in active markets that are accessible to the reporting entity at the measurement date for identical assets and liabilities. • Level 2 —Inputs other than quoted prices in active markets for identical assets and liabilities that are observable either directly or indirectly for substantially the full term of the asset or liability. Level 2 inputs include the following: • quoted prices for similar assets and liabilities in active markets • quoted prices for identical or similar assets or liabilities in markets that are not active • observable inputs other than quoted prices that are used in the valuation of the asset or liabilities (e.g., interest rate and yield curve quotes at commonly quoted intervals) • inputs that are derived principally from or corroborated by observable market data by correlation or other means • Level 3 —Unobservable inputs for the assets or liability (i.e., supported by little or no market activity). Level 3 inputs include management’s own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk). Leases The Company records leases under ASU No. 2016-02 Leases (Topic 842) whereby the Company determines if an arrangement is or contains a lease at inception. For leases with a term of 12 months or less, the Company has elected to not recognize a right-of-use asset or lease liability. The Company’s operating leases are recognized on the consolidated balance sheets as other noncurrent assets, other current liabilities, and other noncurrent liabilities. The Company does not have any finance leases. Right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As the rate implicit on the Company’s leases are not readily determinable, the Company uses an estimate of its incremental borrowing rate for secured borrowings with terms similar to the lease term based on the information available at the lease commencement date in determining the present value of lease payments. Operating lease right-of-use assets also include the effect of any lease payments made, including lease payments made in advance of lease commencement and excludes lease incentives. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term. Research and Development Costs Research and development costs are expensed as incurred. Research and development costs that are paid in advance of performance (if any) are capitalized as a prepaid expense and amortized over the service period as the services are provided. Accrued Research and Manufacturing Contract Costs The Company has entered into various research and development and manufacturing contracts. These agreements are generally cancelable, and related payments are recorded as the corresponding expenses are incurred. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the research studies or clinical trials and manufacturing activities, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs . 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. Revenue Recognition The Company accounts for revenue under ASU No. 2014-19, Revenue from Contracts with Customers (ASC 606). ASC 606 applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, certain collaboration arrangements and financial instruments. ASC 606 provides a five-step framework whereby revenue is recognized when control of promised goods or services is transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company 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; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the performance obligations are satisfied. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration that it is entitled to in exchange for the goods or services the Company transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses whether the goods or services promised within each contract are distinct and, therefore, represent a separate performance obligation. Goods and services that are determined not to be distinct are combined with other promised goods and services until a distinct combined performance obligation is identified. The Company then allocates the transaction price (that is, the amount of consideration the Company expects to be entitled to from a customer in exchange for the promised goods or services) to each performance obligation and recognizes the associated revenue when (or as) each performance obligation is satisfied. The allocation is based upon standalone selling price. The standalone selling price is the price at which an entity would sell a promised good or service separately to a customer. Because the Company have not sold the same goods or services in our contracts separately to any customers on a standalone basis, the Company estimated the standalone selling price of each performance obligation by taking into consideration internal estimates of research and development personnel needed to perform the research and development services, estimates of expected cash outflows to third parties for services and supplies and typical gross profit margins. The Company enters into collaboration and licensing arrangements that are within the scope of ASC 606, under which the Company may exclusively license to third parties’ rights to develop, manufacture and commercialize its product candidates as well as options to acquire additional rights. The terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront license fees; development, regulatory and sales milestone payments; and royalties on net sales of licensed products. Revenue is typically recognized using a cost-to-cost input model as the measure of progress. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete the Company’s performance obligations under an arrangement. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The measure of progress, and thereby periods over which revenue should be recognized, are subject to estimates by management and may change over the course of the research and development and licensing agreement. Such a change could have a material impact on the amount of revenue the Company records in future periods. Amounts received prior to revenue recognition are recorded as deferred revenue in the balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as the current portion of deferred revenue in the balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion in the balance sheets. Customer Options If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options that are not determined to be material rights are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, or options to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. To date, none of our arrangements have included any material rights. The transaction price is allocated to each performance obligation on a relative standalone selling price basis. The observable price of a good or service sold separately provides the best evidence of standalone selling price. However, when standalone selling prices are not readily available, the Company is required to estimate the standalone selling price of each performance obligation. Key assumptions to determine the standalone selling price. Amounts allocated to a material right are not recognized as revenue until the option is exercised or terminates. Milestone Payments For each arrangement that includes milestone payments upon the achievement of performance-based milestones, such as development and regulatory milestones, 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 reversal of revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. Upfront and ongoing development milestones per the Company’s collaboration and license agreement are not subject to refund if the development activities are not successful. The Company reevaluates the probability of achievement of such milestones and any related constraint at each reporting period, and any adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. To date, the Company has not recognized any milestone revenues. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license to the Company’s intellectual property is deemed to be the predominant item to which the royalties relate as it is the primary driver of value, the Company recognizes revenue when the related sales occur in accordance with the sales-based royalty exception. To date, the Company has not recognized any royalty revenue resulting from the Company’s collaboration and licensing agreements. Income Taxes Deferred tax assets and liabilities are recognized for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on the difference between the consolidated financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided to reduce the deferred tax asset to an amount, which, more likely than not, will be realized. The Company recognizes the tax benefit from any uncertain tax positions only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. Interest and penalties associated with uncertain tax positions are recorded as a component of income tax expense. As of December 31, 2023 and 2022 , the Company has no t identified any uncertain tax positions for which reserves would be required. Segment Information Operating segments are defined as components of an entity for which discrete information is available for evaluation by the chief operating decision maker, who is the CEO, in deciding how to allocate resources and in assessing performance. The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. All of the Company’s assets are held in the U.S. Stock-Based Compensation The Company accounts for stock option awards at fair value, which is measured using the Black-Scholes option-pricing model. The measurement date is generally the date of grant. The Company recognizes stock-based compensation expense over the requisite service period, which is generally the vesting period of the respective award. For awards that include performance-based vesting conditions, stock-based compensation expense is recognized using the accelerated attribution method when the performance condition is deemed to be probable. The Company accounts for forfeitures as they occur. The Company determines the fair value of restricted stock awards in reference to the fair value of its common stock less any applicable purchase price The Company classifies stock-based compensation expense in its consolidated statements of operations in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. There was no difference between net loss and comprehensive loss in the accompanying consolidated financial statements. Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted average common shares outstanding during the period. Diluted net loss per share is calculated by adjusting weighted average common shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock and if-converted methods. For purposes of the diluted net income (loss) per share calculation, convertible debt and stock options are considered to be common stock equivalents. All common stock equivalents have been excluded from the calculation of diluted net loss per share as their effect would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share were the same for all periods presented. Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326) Measurement of Credit Losses on Financial Instruments, or ASU 2016-13 . The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Credit losses relating to available-for-sale debt securities will be recorded through an allowance for credit losses rather than as a direct write-down to the security. The Company adopted ASU 2016-13 effective January 1, 2023, and the adoption did not have a material impact on the Company's financial statements.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment	3. Property and Equipment Property and equipment consist of the following (in thousands): December 31, 2023 2022 Laboratory equipment $ 15,653 $ 13,747 Leasehold improvements 3,159 3,447 Furniture and fixtures 1,519 1,638 Office and computer equipment 1,460 1,483 Construction-in-progress 548 5 Property and equipment $ 22,339 $ 20,320 Less: accumulated depreciation and amortization ( 14,597 ) ( 10,220 ) Property and equipment, net $ 7,742 $ 10,100 Depreciation and amortization expense for the years ended December 31, 2023 and 2022 was $ 5.4 million and $ 5.1 million, respectively.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following tables set forth by level, within the fair value hierarchy, the assets carried at fair value (in thousands): Fair value measurements at December 31, 2023 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents – money market funds $ 52,299 $ - $ - $ 52,299 Cash equivalents – government securities 76,483 - - 76,483 Marketable securities – government securities 58,685 - - 58,685 Total financial assets $ 187,467 $ - $ - $ 187,467 Fair value measurements at December 31, 2022 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents – money market funds $ 116,946 $ - $ - $ 116,946 Total financial assets $ 116,946 $ - $ - $ 116,946 Money market funds and government securities are valued by the Company based on quoted market prices, which represent a Level 1 measurement within the fair value hierarchy. There were no transfers among Level 1, Level 2, or Level 3 categories in the periods presented. Assets and Liabilities Not Carried at Fair Value The Company's Long-term debt is carried at amortized cost. The fair value of the Long-term debt was estimated to be $ 38.4 million and $ 29.3 million at December 31, 2023 and 2022, respectively. Fair value was determined using a convertible bond model using a binomial lattice approach. We classified the fair value disclosures for the Long-term debt within level 3 of the fair value hierarchy because the fair value is derived using significant unobservable inputs, which include discount rates and volatility. The carrying value of accounts payable and accrued expenses that are reported on the consolidated balance sheets approximate fair value due to the short-term nature of these liabilities.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	5. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, 2023 2022 Accrued employee compensation and benefits $ 5,478 $ 4,357 Accrued research and development 3,537 1,322 Accrued consulting and professional services 1,026 636 Accrued legal services and license fee 250 92 Other 425 431 Total accrued expenses and other current liabilities $ 10,716 $ 6,838

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2023
Stockholders' Equity Note [Abstract]
Stockholders' Equity	6. Stockholders' Equity ATM Program On May 16, 2023, the Company entered into a sales agreement (the Sales Agreement) with Wedbush Securities, Inc. (Wedbush), as sales agent, pursuant to which the Company could offer, issue and sell up to an aggregate amount of $ 75.0 million of shares of the Company's voting common stock, par value $ 0.0001 per share (Voting Common Stock), from time to time in “at-the-market” (ATM) offerings during the term of the Sales Agreement. No common stock has been sold under this Sales Agreement to date. Equity Offering On June 1, 2023, the Company completed an underwritten public offering of (a) 23,287,134 shares of the Company's Voting Common Stock, at a price of $ 2.00 per share, and (b) pre-funded warrants to purchase up to 47,010,526 shares of the Company's Voting Common Stock, at a price of $ 1.9999 per warrant with an exercise price of $ 0.0001 per share (Pre-Funded Warrants). The Company received aggregate net proceeds of $ 134.7 million after deducting underwriting discounts, commissions and other offering expenses, with $ 42.4 million allocated to the Voting Common Stock and $ 92.3 million allocated to Pre-Funded Warrants. The Pre-Funded Warrants are immediately exercisable subject to certain ownership limitations, have an exercise price of $ 0.0001 per share and do not expire. The Pre-Funded Warrants were determined to be equity classified. As such, proceeds received from the issuance from the Pre-Funded Warrants were recorded as a component of stockholders’ equity within additional paid-in capital. As of December 31, 2023, no Pre-Funded Warrants have been exercised.

Stock Based Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock Based Compensation	7. Stock-Based Compensation 2021 Equity Incentive Plan The 2021 Equity Incentive Plan (the 2021 Plan) was approved by the Company’s Board on April 22, 2021 and became effective immediately, although no awards were permitted to be granted under the 2021 Plan until July 15, 2021. The 2021 Plan replaced the 2018 Plan, however, awards outstanding under the 2018 Plan continue to be go verned by their existing terms. In addition, shares of common stock subject to awards granted under the 2018 Plan that cease to be subject to such awards by forfeiture or otherwise after the termination of the 2018 Plan will be available for issuance under the 2021 Plan. There were 3,278,048 shares of common stock initially reserved for issuance under the 2021 Plan and as of December 31, 2023, there were 4,523,924 sh ares of common stock available for issuance. The number of shares reserved for issuance under the 2021 Plan will be increased automatically on the first business day of each fiscal year, commencing in 2022 and ending in 2031. The aggregate number of common shares that may be issued under the 2021 Plan shall automatically increase by a number equal to the least of (a) 4 % of the total number of shares of common stock actually issued and outstanding on the last day of the preceding fiscal year, or (b) a number of shares common stock determined by the Company’s Board. 2021 Employee Stock Purchase Plan The 2021 Employee Stock Purchase Plan (the "2021 ESPP") was approved by the Company’s Board on April 22, 2021 and became effective immediately, although no awards were permitted to be granted under the 2021 Plan until July 15, 2021. A total of 254,390 shares of common stock were initially reserved for issuance under the 2021 ESPP. As of December 31, 2023 and 2022, there were 146,380 shares issued under the 2021 ESPP. As of December 31, 2023, there were 589,344 shares of common stock available for issuance under the 2021 ESPP. The number of shares reserved for issuance will automatically be increased on the first business day of each fiscal year, commencing on January 1, 2022 and ending on January 1, 2041. The aggregate number of shares of common stock that may be issued under the 2021 ESPP shall automatically increase by a number equal to the least of (i) one percent ( 1 %) of the total number of shares of common stock actually issued and outstanding on the last day of the preceding fiscal year, or (ii) a number of shares of common stock determined by the Company’s Board. Stock Compensation Stock-based compensation expense related to stock options and the stock purchase plan for the years ended December 31, 2023 and 2022 was classified in the consolidated statement of operations as follows (in thousands): Year Ended 2023 2022 Research and development $ 2,876 $ 1,626 General and administrative 2,332 2,925 Total stock-based compensation expense $ 5,208 $ 4,551 S tock Options The Company typically grants stock options at exercise prices deemed by the Board to be equal to the fair value of the common stock at the time of grant, based upon the quoted price of the Company’s common stock. The fair value of stock option grants is estimated using the Black-Scholes option-pricing model. The Company lacks sufficient company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. For options with service-based vesting conditions, the expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does no t expect to pay any cash dividends in the foreseeable future. The weighted-average for each of the assumptions the Company used to determine the grant-date fair value of options granted were as follows : Year Ended December 31, 2023 2022 Risk free interest rate 3.95 % 2.40 % Expected term (in years) 6.36 6.24 Expected dividend yield 0 % 0 % Expected volatility of underlying common stock 87 % 81 % The following table summarizes the stock option a ctivity: Stock Weighted Weighted Intrinsic Outstanding January 1, 2023 5,230,537 $ 5.35 8.49 $ — Granted 8,544,660 2.70 Exercised ( 316,441 ) 2.25 Canceled ( 3,060,506 ) 5.10 Outstanding December 31, 2023 10,398,250 $ 3.34 8.87 $ 28,278 Options vested or expected to vest as of December 31, 2023 10,398,250 $ 3.34 8.87 $ 28,278 Stock options exercisable as of December 31, 2023 1,765,282 $ 4.88 6.97 $ 3,016 Other information related to the option activity for the years ended December 31, 2023 and 2022: Year Ended 2023 2022 Weighted-average fair value of options granted $ 2.17 $ 2.80 Intrinsic value of options exercised (in thousands) 152 62 As of December 31, 2023, the unrecognized compensation cost related to outstanding options was $ 18.8 million, which is expected to be recognized over a weighted-average period of 3.24 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes During the years ended December 31, 2023 and 2022, the Company did not record an income tax provision due to the losses incurred and a full valuation allowance provided on the net deferred tax assets. A reconciliation of the federal statutory income tax rate to the effective tax rate is as follows : Year Ended December 31, 2023 2022 Taxes at U.S. statutory rate 21.0 % 21.0 % Changes from statutory rate: State taxes, net of federal benefit 8.5 % 8.3 % Tax credits 5.4 % 5.1 % Share-based compensation ( 0.7 )% ( 0.9 )% Change in valuation allowance ( 34.1 )% ( 33.8 )% Other ( 0.1 )% 0.3 % Effective income tax rate 0.0 % 0.0 % Deferred tax assets and liabilities reflect the net tax effects of net operating loss carryovers and temporary differences between the carrying amount of assets and liabilities for financial reporting and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities were as follows (in thousands): Year Ended December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 23,201 $ 23,391 Tax credits 16,939 10,191 Deferred revenue 4,305 1,332 Depreciation and amortization 1,159 824 Amortization 479 525 Stock-based compensation 1,126 707 Leasehold liability 17,044 15,489 Capitalized R&D costs 31,515 14,380 Other 3,824 1,441 Total deferred tax assets 99,592 68,280 Deferred tax liabilities: Right of use Asset ( 17,346 ) ( 16,411 ) Valuation allowance ( 82,246 ) ( 51,869 ) Net deferred tax assets and liabilities $ - $ - In determining the need for a valuation allowance, the Company has given consideration to its cumulative book income and loss positions. The Company has assessed the available means of recovering deferred tax assets, including the ability to carryback net operating losses, the existence of reversing taxable temporary differences, the availability of tax planning strategies and forecasted future taxable income. As of December 31, 2023, the Company maintains a full valuation allowance against its net deferred tax assets. The valuation allowance increased by $ 30.4 million and $ 22.4 million during the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, the Company had U.S. federal net operating loss carryforwards of approximately $ 84.8 million. The U.S. federal net operating losses have an indefinite life carryforward. As of December 31, 2023, the Company had Massachusetts net operating loss carryforwards of approximately $ 85.3 million that expire at various dates through 2042 . As of December 31, 2023, the Company had U.S. R&D federal credit carryforwards of approximately $ 11.7 million that expire at various dates through 2042 . As of December 31, 2023, the Company had U.S. state R&D tax credit carryforwards of approximately $ 6.7 million that expire at various dates through 2037 . Under Sections 382 and 383 of the U.S. Internal Revenue Code, if a corporation undergoes an ownership change, the corporation's ability to use its pre-change net operating loss carryforwards and other pre-change attributes, such as net operating losses and research tax credits, to offset its post-change income and taxes may be limited. In general, an ownership change generally occurs if there is a cumulative change in ownership by 5% stockholders that exceeds 50 percentage points over a rolling three-year period. Similar rules may apply under U.S. state tax laws. The Company has experienced an ownership change in the past and may experience ownership changes in the future as a result of future transactions in its share capital, some of which may be outside the control of the Company. As a result, if the Company earns net taxable income, its ability to use its pre-change net operating loss carryforwards, or other pre-change tax attributes, to offset U.S. federal and state taxable income and taxes may be subject to significant limitations. The Company accounted for uncertain tax positions using a more likely than not threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors that include, but are not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity and changes in facts or circumstances related to a tax position. The Company evaluates uncertain tax positions on an annual basis and adjusts the level of the liability to reflect any subsequent changes in the relevant facts surrounding the uncertain positions. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. For the years ended December 31, 2023 and 2022 , there were no accrued interest or penalties in the consolidated statements of operations. The Company is subject to taxation for federal and Massachusetts purposes. As of December 31, 2023 , the Company is subject to examination by these taxing authorities for all years since inception.

Collaboration and License Agree

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2023
Collaboration And License Agreements [Abstract]
Collaboration and License Agreements	9. Collaboration and License Agreements Amgen On May 8, 2023 , the Company entered into a Collaboration Agreement with Amgen Inc. (the Amgen Agreement) to identify antigens recognized by T cells in patients with Crohn’s disease in accordance with a research plan. Under the terms of the Amgen Agreement, Amgen will retain all global development and commercialization rights. The proceeds from the Amgen Agreements included an upfront payment of $ 30.0 million, which was collected in July 2023. In addition, the Company is eligible to earn success-based milestone payments of over $ 500 million, based upon the achievement of certain clinical development and commercial milestones, as well as tiered single-digit royalty payments on net sales of products developed from the collaboration, subject to reductions set forth in the Amgen Agreement. The Company concluded that Amgen meets the definition of a customer, as the Company is delivering research and development activities and a license of intellectual property. The Company identified performance obligations for research and development activities, the license, data reporting and participation in joint steering and research committees, which were determined to be a single combined performance obligation due to the services and licenses being highly interrelated. For a certain time period during the term of the Amgen Agreement, Amgen has an option to add targets to the collaboration for payments specified in the agreement. Pursuant to the Amgen Agreement, the option for Amgen to select additional targets and to license, develop, and commercialize targets is not a performance obligation at the outset as these are customer options that do not represent material rights. The Company looked to the promises in the arrangement to determine the method of recognition that best depicted the transfer of the services and the satisfaction of the combined performance obligations. The Company concluded that the performance of the research services over the expected research term was the predominant promise within the performance obligation. The Company will recognize the revenue associated with the performance obligation using an input method. The method of measuring progress towards delivery of the services incorporates actual internal and external costs incurred, relative to total internal and external costs expected to be incurred to satisfy the performance obligation. Changes in estimates of total internal and external costs expected to be incurred are recognized in the period of change as a cumulative catch-up adjustment. As costs are incurred, the Company will recognized revenue over time. At this time, it is estimated that the research term will be approximately 3 years. The Company determined the $ 30.0 million upfront payment to be the entirety of the consideration to be included in the transaction price. The option to add additional targets was not included in the transaction price as this option was assessed to be improbable at this time. The potential milestone and royalty payments that the Company is eligible to receive were also excluded from the transaction price, as all milestone and royalty amounts were fully constrained based on the assessed probability of achievement. The Company will continue to assess the probability of the option to add additional targets and the probability of milestone achievement throughout the research term and will adjust the consideration in the contract accordingly. For the year ended December 31, 2023, the Company recognized $ 14.2 million of revenue associated with the Amgen Agreement. As of December 31, 2023, the Company recorded $ 15.8 million of deferred revenue, of which $ 5.6 million is classified as long-term. Novartis In March 2020 , the Company entered into a Collaboration and License Agreement (the Novartis Agreement) with Novartis Institutes For BioMedical Research, Inc. (Novartis) to collaborate on their research efforts to discover and develop novel TCR-T therapies. At the inception date of the Novartis Agreement, Novartis or its affiliates held an ownership interest of more than 10 % in the Company, and at December 31, 2023 and 2022, Novartis held less than 10 % of the common shares outstanding. Under the Novartis Agreement, the Company was to identify and characterize TCRs in accordance with a research plan, and transfer data arising from the research plan. The Novartis Agreement provided for payments of an upfront fee of $ 20.0 million, research funding totaling $ 10.0 million, and potential milestone payments contingent on clinical, regulatory and sales success. The Company concluded that the performance of the research services was the predominant performance obligation and was recognizing the revenue associated with the performance obligation using the input method, according to the actual costs incurred as a percentage of total expected costs to complete the research services. The Company determined that the $ 20.0 million upfront payment, together with the $ 10.0 million of estimated research costs to be reimbursed by Novartis to be the entirety of the consideration to be included in the transaction price as of the outset of the arrangement. The potential milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestone amounts were fully constrained based on the assessed probability of achievement. During the years ended December 31, 2023 and 2022, the Company recognized $ 5.8 million and $ 13.5 million, respectively, of revenue associated with the Novartis Agreement, of which $ 1.9 million and $ 4.5 million, respectively, related to cost reimbursements under the Novartis Agreement that offset costs incurred within research and development expenses in the statements of operations. The research term ended in March 2023.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Leases The Company leases two facilities at 880 Winter Street and 830 Winter Street in Waltham, Massachusetts. Each lease has specified terms and includes renewal options. Given uncertainty as to the Company's intentions with respect to these leases, the renewal options were not deemed reasonably certain. On November 8, 2023, the Company entered into a lease amendment extending the expiration date of the 830 Winter Street Lease from September 30, 2024 to October 31, 2029 and provides for one option to renew the 830 Winter Street Lease for a five-year period commencing on November 1, 2029 , resulting in an increase in the lease liability of $ 6.2 million. Summary of lease cost The following table summarizes the presentation in the Company's consolidated balance sheets of its operating leases (in thousands): As of December 31, 2023 2022 Assets: Operating lease assets $ 63,492 $ 59,102 Liabilities: Operating lease liabilities, current 3,246 3,681 Operating lease liabilities, net of current portion 59,140 53,013 Total operating lease liabilities $ 62,386 $ 56,694 The following table summarizes the effect of lease costs in the Company's consolidated statement of operations (in thousands): Years Ended December 31, 2023 2022 Operating lease costs $ 10,626 $ 3,264 Short-term lease costs 44 332 Variable lease costs 5,120 1,551 Total lease costs $ 15,790 $ 5,147 During the years ended December 31, 2023 and 2022, the Company made cash payments for operating leases of $ 9.4 million and $ 2.0 million, respectively. As of December 31, 2023, future payments of operating lease liabilities are as follows (in thousands): As of December 31, 2023 2024 $ 9,507 2025 10,463 2026 10,944 2027 11,255 2028 and thereafter 53,734 Total future payments of operating lease liabilities 95,903 Less: imputed interest ( 33,517 ) Present value of operating lease liabilities $ 62,386 As of December 31, 2023, the weighted average remaining lease term was 8.6 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 10.3 % . As of December 31, 2022, the weighted average remaining lease term was 9.7 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 9.8 % . Brigham and Women’s License Agreement The Company obtained the worldwide exclusive license to its foundational technology from The Brigham and Women’s Hospital, Inc. (or BWH). The license, as amended, grants worldwide exclusive use to the patent underlying the TargetScan technology in exchange for fees including development milestones and various royalties on product sales should they occur in the future. Royalty Agreement In June 2018, the Company amended and restated an existing royalty agreement with one of its founders. Under the amended and restated royalty agreement, the Company agreed to pay the founder an aggregate royalty of 1 % of net sales of any product sold by the Company or by any of its direct or indirect licensees for use in the treatment of any disease or disorder covered by a pending patent application or issued patent held or controlled by the Company as of the last date that the founder was providing services to the Company as a director or consultant under a written agreement in perpetuity. Royalties are payable with respect to each applicable product for a defined period of time set forth in the royalty agreement. The founder assigned his rights and obligations under the royalty agreement to one of his affiliated entities in January 2021.

Loan and Security Agreement

Loan and Security Agreement	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Loan and Security Agreement	11. Loan and Security Agreement On September 9, 2022 (the Closing Date), the Company entered into a Loan and Security Agreement (the Loan Agreement) with K2 HealthVentures LLC (K2HV), pursuant to which convertible term loans in an aggregate principal amount of up to $ 60 million is available to the Company in three tranches, subject to certain terms and conditions. The Company drew the first tranche of $ 30 million from K2HV on the Closing Date. The Company has the option to draw the second tranche of $ 10 million upon the achievement of certain financial and clinical milestones and an uncommitted third tranche of $ 20 million may be funded by joint agreement of the Company and K2HV. On the Closing Date, the Company paid a facility fee of $ 0.4 million to K2HV and is subject to an additional 1 % of the principal amount of any amount drawn on third tranche. The term loans mature on September 1, 2026 (the Maturity Date), and will be subject to interest only payments for 24 months, which can be extended to 36 months upon achievement of certain financial and clinical milestones, following which the term loans will amortize in equal monthly installments until maturity. The Company has the ability to repay the loan at any time either in cash or in shares, subject to applicable premiums as specified in the Loan Agreement. The term loans will accrue interest at a per annum rate equal to the greater of (i) 8.75 % and (ii) the sum of (A) the prime rate (as last quoted in The Wall Street Journal) and (B) 4.75 %, subject to a cap of 9.90 %. At December 31, 2023 the applicable interest rate is 9.90 %. The lenders may elect at any time following the closing prior to the payment in full of the term loans to convert any portion of the principal amount of the term loans then outstanding into shares of the Company's common stock. The first tranche of the loan is convertible at the option of K2HV at a conversion price of $ 4.785 per share and future tranches will be convertible as specified in the agreement, provided that, such price shall be subject to the applicable conversion price floor and other adjustments in accordance with the Loan Agreement. The embedded conversion option meets the derivative accounting scope exception since the embedded conversion option is indexed to the Company’s own common stock and qualifies for classification within stockholders’ equity. The Company has the option to prepay all, but not less than all, of the outstanding principal balance of the term loans under the Loan Agreement subject to a prepayment fee ranging from 4 % to 1 % depending upon when the prepayment occurs. The Company is obligated to pay a final fee equal to 6.00 % of the aggregate amount of the term loans funded (the Exit Fee), to occur upon the earliest of (i) the maturity date, (ii) the acceleration of the term loans, and (iii) the prepayment of the term loans. If, upon equity conversion, K2HV receives gross proceeds in an amount equal to at least 1.5 multiplied by the principal amount converted from the sale or other disposition of such Conversion Shares (as defined in the Loan Agreement), then as to such principal amount, the Exit Fee will be reduced to zero. The Company’s obligations under the Loan Agreement are secured by a first priority security interest in substantially all of its assets (other than intellectual property), subject to certain exceptions. The Loan Agreement contains customary representations and warranties, and also includes customary events of default, including payment default, breach of covenants, change of control, and material adverse effects. The Loan Agreement restricts certain activities, such as disposing of the Company’s business or certain assets, incurring additional debt or liens or making payments on other debt, making certain investments and declaring dividends, acquiring or merging with another entity, engaging in transactions with affiliates or encumbering intellectual property, among others. During the term of the Loan Agreement, the Company must maintain minimum unrestricted cash and cash equivalents equal to 5.0 times the average monthly cash burn measured over the trailing three-month period. Upon the occurrence of an event of default, a default interest rate of an additional 5 % per annum may be applied to the outstanding loan balances, and the Lender may declare all outstanding obligations immediately due and payable and exercise all of its rights and remedies as set forth in the Loan Agreement and under applicable law. The Company recorded $ 3.8 million and $ 1.2 million in interest expense for the years ended December 31, 2023 and 2022 , respectively. The effective interest rate on the Loan Agreement, including the amortization of the debt discount and issuance costs, and accretion of the Exit Fee, was 12.82 % at December 31, 2023. Future principal payments as of December 31, 2023 are as follows: 2024 $ 3,427 2025 14,588 2026 11,985 Total principal payments 30,000 Plus: Final payment fee 1,800 Less: unamortized debt discount and final fee ( 1,753 ) Total debt 30,047 Less: current portion of long-term debt ( 3,347 ) Long-term debt, net $ 26,700

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Retirement Plan	12. Retirement Plan The Company initiated a defined contribution plan under Section 401(k) of the IRC (the Plan) covering all qualified employees effective January 1, 2019. Employee contributions are voluntary and are determined on an individual basis subject to the maximum allowable under federal tax regulations. The Company made contributions to the Plan of $ 0.7 million and $ 0.6 million for the years ended December 31, 2023 and 2022 , respectively.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Net Loss Per Share	13. Net Loss Per Share Net Loss Per Share Basic and diluted net loss per share was calculated as follows (in thousands, except share and per share data): Year Ended December 31, 2023 2022 Numerator: Net loss $ ( 89,218 ) $ ( 66,221 ) Denominator: Weighted-average common shares outstanding, basic and diluted 65,599,858 24,048,267 Net loss per share, basic and diluted $ ( 1.36 ) $ ( 2.75 ) The 47,010,526 shares of the Company's common stock issuable upon exercise of the Pre-Funded Warrants described in Note 6 are included as outstanding common stock in the calculation of basic and diluted net loss per share. The Company has two classes of common stock, each with identical participation rights to earnings and liquidation preferences, and therefore the calculation of net loss per share as described above is identical to the calculation under the two-class method. The Company excluded the following potential common shares from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: December 31, 2023 2022 Options to purchase common stock 10,398,250 5,230,537 Common stock issuable upon conversion of Loan Agreement 6,269,592 2,116,780 Total 16,667,842 7,347,317

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements reflect the operations of the Company and the Company’s wholly owned subsidiary, TScan Securities Corporation. The accompanying consolidated financial statements have been prepared in conformity with US GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative US GAAP as found in the Accounting Standards Codification, or ASC, and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in accordance with US GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. The Company bases its estimates on historical experience, known trends and other market-specific or relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Actual results may differ from those estimates or assumptions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash includes cash in readily available checking and money market accounts. Cash equivalents include all highly liquid investments maturing within 90 days from the date of purchase. The cash equivalents consisted of money market funds and government securities.
Restricted Cash	Restricted Cash In connection with the Company’s facility lease agreements, the Company is required to provide letters of credit totaling of $ 5.0 million for the benefit of the landlords to serve as security deposits. As of December 31, 2023 and 2022 , the cash securing the letter of credit was classified as restricted cash (non-current) on the consolidated balance sheets.
Marketable Securities	Marketable Securities The Company classifies all of its marketable securities as available-for-sale based upon its intent with regard to such investments. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income (loss). The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest and investment income. Realized gains and losses and declines in value judged to be other than temporary on available-for-sale securities, are included in interest and investment income. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest and investment income. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company’s cash deposits on hand at any one financial institution often exceed federally insured limits. The Company places its cash in financial institutions that management believes to be of high credit quality. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.
Property and Equipment	Property and Equipment Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the respective assets as follows: Estimated useful life Laboratory equipment 3 - 5 years Furniture and fixtures 3 - 5 years Office and computer equipment 3 - 5 years Software 3 - 5 years Leasehold improvements Shorter of the asset's estimated useful life or the remaining lease term Major additions and betterments are capitalized; expenditures for repairs and maintenance, which do not improve or extend the life of the respective assets, are charged to operating expense as incurred. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets to be held and used, including property and equipment, are tested for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be fully recoverable. Evaluation of the recoverability of the asset or asset group is based on an estimate of undiscounted future cash flows resulting from the use of the asset or asset group and its eventual disposition. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the asset or asset group, an impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value. The Company did not record any impairment losses on long-lived assets during the periods presented.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under US GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the user of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1 —Unadjusted quoted prices in active markets that are accessible to the reporting entity at the measurement date for identical assets and liabilities. • Level 2 —Inputs other than quoted prices in active markets for identical assets and liabilities that are observable either directly or indirectly for substantially the full term of the asset or liability. Level 2 inputs include the following: • quoted prices for similar assets and liabilities in active markets • quoted prices for identical or similar assets or liabilities in markets that are not active • observable inputs other than quoted prices that are used in the valuation of the asset or liabilities (e.g., interest rate and yield curve quotes at commonly quoted intervals) • inputs that are derived principally from or corroborated by observable market data by correlation or other means • Level 3 —Unobservable inputs for the assets or liability (i.e., supported by little or no market activity). Level 3 inputs include management’s own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk).
Leases	Leases The Company records leases under ASU No. 2016-02 Leases (Topic 842) whereby the Company determines if an arrangement is or contains a lease at inception. For leases with a term of 12 months or less, the Company has elected to not recognize a right-of-use asset or lease liability. The Company’s operating leases are recognized on the consolidated balance sheets as other noncurrent assets, other current liabilities, and other noncurrent liabilities. The Company does not have any finance leases. Right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As the rate implicit on the Company’s leases are not readily determinable, the Company uses an estimate of its incremental borrowing rate for secured borrowings with terms similar to the lease term based on the information available at the lease commencement date in determining the present value of lease payments. Operating lease right-of-use assets also include the effect of any lease payments made, including lease payments made in advance of lease commencement and excludes lease incentives. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development costs that are paid in advance of performance (if any) are capitalized as a prepaid expense and amortized over the service period as the services are provided.
Accrued Research and Manufacturing Contract Costs	Accrued Research and Manufacturing Contract Costs The Company has entered into various research and development and manufacturing contracts. These agreements are generally cancelable, and related payments are recorded as the corresponding expenses are incurred. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the research studies or clinical trials and manufacturing activities, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs
Patent Costs	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.
Revenue Recognition	Revenue Recognition The Company accounts for revenue under ASU No. 2014-19, Revenue from Contracts with Customers (ASC 606). ASC 606 applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, certain collaboration arrangements and financial instruments. ASC 606 provides a five-step framework whereby revenue is recognized when control of promised goods or services is transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company 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; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the performance obligations are satisfied. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration that it is entitled to in exchange for the goods or services the Company transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses whether the goods or services promised within each contract are distinct and, therefore, represent a separate performance obligation. Goods and services that are determined not to be distinct are combined with other promised goods and services until a distinct combined performance obligation is identified. The Company then allocates the transaction price (that is, the amount of consideration the Company expects to be entitled to from a customer in exchange for the promised goods or services) to each performance obligation and recognizes the associated revenue when (or as) each performance obligation is satisfied. The allocation is based upon standalone selling price. The standalone selling price is the price at which an entity would sell a promised good or service separately to a customer. Because the Company have not sold the same goods or services in our contracts separately to any customers on a standalone basis, the Company estimated the standalone selling price of each performance obligation by taking into consideration internal estimates of research and development personnel needed to perform the research and development services, estimates of expected cash outflows to third parties for services and supplies and typical gross profit margins. The Company enters into collaboration and licensing arrangements that are within the scope of ASC 606, under which the Company may exclusively license to third parties’ rights to develop, manufacture and commercialize its product candidates as well as options to acquire additional rights. The terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront license fees; development, regulatory and sales milestone payments; and royalties on net sales of licensed products. Revenue is typically recognized using a cost-to-cost input model as the measure of progress. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete the Company’s performance obligations under an arrangement. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The measure of progress, and thereby periods over which revenue should be recognized, are subject to estimates by management and may change over the course of the research and development and licensing agreement. Such a change could have a material impact on the amount of revenue the Company records in future periods. Amounts received prior to revenue recognition are recorded as deferred revenue in the balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as the current portion of deferred revenue in the balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion in the balance sheets.
Customer Options	Customer Options If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options that are not determined to be material rights are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, or options to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. To date, none of our arrangements have included any material rights. The transaction price is allocated to each performance obligation on a relative standalone selling price basis. The observable price of a good or service sold separately provides the best evidence of standalone selling price. However, when standalone selling prices are not readily available, the Company is required to estimate the standalone selling price of each performance obligation. Key assumptions to determine the standalone selling price. Amounts allocated to a material right are not recognized as revenue until the option is exercised or terminates.
Milestone Payments	Milestone Payments For each arrangement that includes milestone payments upon the achievement of performance-based milestones, such as development and regulatory milestones, 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 reversal of revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. Upfront and ongoing development milestones per the Company’s collaboration and license agreement are not subject to refund if the development activities are not successful. The Company reevaluates the probability of achievement of such milestones and any related constraint at each reporting period, and any adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. To date, the Company has not recognized any milestone revenues.
Royalties	Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license to the Company’s intellectual property is deemed to be the predominant item to which the royalties relate as it is the primary driver of value, the Company recognizes revenue when the related sales occur in accordance with the sales-based royalty exception. To date, the Company has not recognized any royalty revenue resulting from the Company’s collaboration and licensing agreements.
Income Taxes	Income Taxes Deferred tax assets and liabilities are recognized for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on the difference between the consolidated financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided to reduce the deferred tax asset to an amount, which, more likely than not, will be realized. The Company recognizes the tax benefit from any uncertain tax positions only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. Interest and penalties associated with uncertain tax positions are recorded as a component of income tax expense. As of December 31, 2023 and 2022 , the Company has no t identified any uncertain tax positions for which reserves would be required.
Segment Information	Segment Information Operating segments are defined as components of an entity for which discrete information is available for evaluation by the chief operating decision maker, who is the CEO, in deciding how to allocate resources and in assessing performance. The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. All of the Company’s assets are held in the U.S.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock option awards at fair value, which is measured using the Black-Scholes option-pricing model. The measurement date is generally the date of grant. The Company recognizes stock-based compensation expense over the requisite service period, which is generally the vesting period of the respective award. For awards that include performance-based vesting conditions, stock-based compensation expense is recognized using the accelerated attribution method when the performance condition is deemed to be probable. The Company accounts for forfeitures as they occur. The Company determines the fair value of restricted stock awards in reference to the fair value of its common stock less any applicable purchase price The Company classifies stock-based compensation expense in its consolidated statements of operations in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. There was no difference between net loss and comprehensive loss in the accompanying consolidated financial statements.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted average common shares outstanding during the period. Diluted net loss per share is calculated by adjusting weighted average common shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock and if-converted methods. For purposes of the diluted net income (loss) per share calculation, convertible debt and stock options are considered to be common stock equivalents. All common stock equivalents have been excluded from the calculation of diluted net loss per share as their effect would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share were the same for all periods presented.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326) Measurement of Credit Losses on Financial Instruments, or ASU 2016-13 . The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Credit losses relating to available-for-sale debt securities will be recorded through an allowance for credit losses rather than as a direct write-down to the security. The Company adopted ASU 2016-13 effective January 1, 2023, and the adoption did not have a material impact on the Company's financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Property and Equipment Stated at Cost and Depreciated Using Straight-line Method Over Estimated Useful Lives	Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the respective assets as follows: Estimated useful life Laboratory equipment 3 - 5 years Furniture and fixtures 3 - 5 years Office and computer equipment 3 - 5 years Software 3 - 5 years Leasehold improvements Shorter of the asset's estimated useful life or the remaining lease term

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consist of the following (in thousands): December 31, 2023 2022 Laboratory equipment $ 15,653 $ 13,747 Leasehold improvements 3,159 3,447 Furniture and fixtures 1,519 1,638 Office and computer equipment 1,460 1,483 Construction-in-progress 548 5 Property and equipment $ 22,339 $ 20,320 Less: accumulated depreciation and amortization ( 14,597 ) ( 10,220 ) Property and equipment, net $ 7,742 $ 10,100

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Assets Carried at Fair Value on a Hierarchy Basis	The following tables set forth by level, within the fair value hierarchy, the assets carried at fair value (in thousands): Fair value measurements at December 31, 2023 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents – money market funds $ 52,299 $ - $ - $ 52,299 Cash equivalents – government securities 76,483 - - 76,483 Marketable securities – government securities 58,685 - - 58,685 Total financial assets $ 187,467 $ - $ - $ 187,467 Fair value measurements at December 31, 2022 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents – money market funds $ 116,946 $ - $ - $ 116,946 Total financial assets $ 116,946 $ - $ - $ 116,946

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, 2023 2022 Accrued employee compensation and benefits $ 5,478 $ 4,357 Accrued research and development 3,537 1,322 Accrued consulting and professional services 1,026 636 Accrued legal services and license fee 250 92 Other 425 431 Total accrued expenses and other current liabilities $ 10,716 $ 6,838

Stock Based Compensation (Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Weighted-average for Each of The Assumptions The Company Used to Determine The Grant-date Fair Value of Options Granted	The weighted-average for each of the assumptions the Company used to determine the grant-date fair value of options granted were as follows : Year Ended December 31, 2023 2022 Risk free interest rate 3.95 % 2.40 % Expected term (in years) 6.36 6.24 Expected dividend yield 0 % 0 % Expected volatility of underlying common stock 87 % 81 %
Summary of Stock Option Activity	The following table summarizes the stock option a ctivity: Stock Weighted Weighted Intrinsic Outstanding January 1, 2023 5,230,537 $ 5.35 8.49 $ — Granted 8,544,660 2.70 Exercised ( 316,441 ) 2.25 Canceled ( 3,060,506 ) 5.10 Outstanding December 31, 2023 10,398,250 $ 3.34 8.87 $ 28,278 Options vested or expected to vest as of December 31, 2023 10,398,250 $ 3.34 8.87 $ 28,278 Stock options exercisable as of December 31, 2023 1,765,282 $ 4.88 6.97 $ 3,016
Summary of Other Information Related to Option Activity	Other information related to the option activity for the years ended December 31, 2023 and 2022: Year Ended 2023 2022 Weighted-average fair value of options granted $ 2.17 $ 2.80 Intrinsic value of options exercised (in thousands) 152 62
Summary of Stock-based Compensation Expense	Stock-based compensation expense related to stock options and the stock purchase plan for the years ended December 31, 2023 and 2022 was classified in the consolidated statement of operations as follows (in thousands): Year Ended 2023 2022 Research and development $ 2,876 $ 1,626 General and administrative 2,332 2,925 Total stock-based compensation expense $ 5,208 $ 4,551 S

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Reconciliation of the Federal Statutory Income Tax Rate to the Effective Tax Rate	A reconciliation of the federal statutory income tax rate to the effective tax rate is as follows : Year Ended December 31, 2023 2022 Taxes at U.S. statutory rate 21.0 % 21.0 % Changes from statutory rate: State taxes, net of federal benefit 8.5 % 8.3 % Tax credits 5.4 % 5.1 % Share-based compensation ( 0.7 )% ( 0.9 )% Change in valuation allowance ( 34.1 )% ( 33.8 )% Other ( 0.1 )% 0.3 % Effective income tax rate 0.0 % 0.0 %
Summary of Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities were as follows (in thousands): Year Ended December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 23,201 $ 23,391 Tax credits 16,939 10,191 Deferred revenue 4,305 1,332 Depreciation and amortization 1,159 824 Amortization 479 525 Stock-based compensation 1,126 707 Leasehold liability 17,044 15,489 Capitalized R&D costs 31,515 14,380 Other 3,824 1,441 Total deferred tax assets 99,592 68,280 Deferred tax liabilities: Right of use Asset ( 17,346 ) ( 16,411 ) Valuation allowance ( 82,246 ) ( 51,869 ) Net deferred tax assets and liabilities $ - $ -

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Maturity of Future Payments Of Operating Lease Liabilities	As of December 31, 2023, future payments of operating lease liabilities are as follows (in thousands): As of December 31, 2023 2024 $ 9,507 2025 10,463 2026 10,944 2027 11,255 2028 and thereafter 53,734 Total future payments of operating lease liabilities 95,903 Less: imputed interest ( 33,517 ) Present value of operating lease liabilities $ 62,386
Summary Of presentation of operating lease In consolidated balance sheet	The following table summarizes the presentation in the Company's consolidated balance sheets of its operating leases (in thousands): As of December 31, 2023 2022 Assets: Operating lease assets $ 63,492 $ 59,102 Liabilities: Operating lease liabilities, current 3,246 3,681 Operating lease liabilities, net of current portion 59,140 53,013 Total operating lease liabilities $ 62,386 $ 56,694
Lease cost in the Company's consolidated statement of operations	The following table summarizes the effect of lease costs in the Company's consolidated statement of operations (in thousands): Years Ended December 31, 2023 2022 Operating lease costs $ 10,626 $ 3,264 Short-term lease costs 44 332 Variable lease costs 5,120 1,551 Total lease costs $ 15,790 $ 5,147

Loan and Security Agreement (Ta

Loan and Security Agreement (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	Future principal payments as of December 31, 2023 are as follows: 2024 $ 3,427 2025 14,588 2026 11,985 Total principal payments 30,000 Plus: Final payment fee 1,800 Less: unamortized debt discount and final fee ( 1,753 ) Total debt 30,047 Less: current portion of long-term debt ( 3,347 ) Long-term debt, net $ 26,700

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss Per Share	Basic and diluted net loss per share was calculated as follows (in thousands, except share and per share data): Year Ended December 31, 2023 2022 Numerator: Net loss $ ( 89,218 ) $ ( 66,221 ) Denominator: Weighted-average common shares outstanding, basic and diluted 65,599,858 24,048,267 Net loss per share, basic and diluted $ ( 1.36 ) $ ( 2.75 )
Summary of Potential Common Shares Excluded from Computation of Diluted Net Loss per Share	The Company excluded the following potential common shares from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: December 31, 2023 2022 Options to purchase common stock 10,398,250 5,230,537 Common stock issuable upon conversion of Loan Agreement 6,269,592 2,116,780 Total 16,667,842 7,347,317

Nature of Business and Basis _2

Nature of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Jun. 01, 2023
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Date of incorporation	Apr. 17, 2018
Net losses	$ 89,218	$ 66,221
Accumulated deficit	$ 247,597	$ 158,379
Voting Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, shares authorized	300,000,000	300,000,000
Non-voting Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, shares authorized	10,000,000	10,000,000
Initial Public Offering | Voting Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Sale of stock price per share			$ 2

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Restricted cash	$ 5,031,000	$ 5,037,000
Uncertain tax positions	0	$ 0
Letter of Credit
Restricted cash	$ 5,000,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Property and Equipment Stated at Cost and Depreciated Using Straight-line Method Over Estimated Useful Lives (Details)	Dec. 31, 2023
Laboratory Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Laboratory Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Furniture and Fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Furniture and Fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Office and Computer Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office and Computer Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Software | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Software | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration]	us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment	$ 22,339	$ 20,320
Less: accumulated depreciation and amortization	(14,597)	(10,220)
Property and equipment, net	7,742	10,100
Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property and equipment	15,653	13,747
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment	3,159	3,447
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	1,519	1,638
Office and Computer Equipment
Property, Plant and Equipment [Line Items]
Property and equipment	1,460	1,483
Construction-in-Progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 548	$ 5

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 5.4	$ 5.1

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets Carried at Fair Value on a Hierarchy Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets, Fair Value Disclosure [Abstract]
Total financial assets	$ 187,467	$ 116,946
Government Securities
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	76,483
Marketable securities, fair value disclosure	58,685
Cash Equivalents - Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	52,299	116,946
Level 1
Assets, Fair Value Disclosure [Abstract]
Total financial assets	187,467	116,946
Level 1 | Government Securities
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	76,483
Marketable securities, fair value disclosure	58,685
Level 1 | Cash Equivalents - Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	$ 52,299	$ 116,946

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, assets, level 1 to level 2 transfers	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers	0	0
Fair value, assets, transfers into level 3	0	0
Fair value, assets, transfers out of level 3	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-term debt	$ 38,400	$ 29,300

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued employee compensation and benefits	$ 5,478	$ 4,357
Accrued research and development	3,537	1,322
Accrued consulting and professional services	1,026	636
Accrued legal services and license fee	250	92
Other	425	431
Total accrued expenses and other current liabilities	$ 10,716	$ 6,838

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jun. 01, 2023	May 16, 2023	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Issuance of common stock, net of offering cost/ ESPP plan			$ 42,414	$ 193
Net proceeds from common stock and warrants after deducting underwriting discounts, commissions and other offering expenses	$ 134,700
Proceeds from issuance of pre-funded warrants, net of offering costs	92,300		92,318
Proceeds from issuance of common stock, net of offering costs	$ 42,400		$ 42,414
Voting Common Stock
Class of Stock [Line Items]
Common stock, par value			$ 0.0001	$ 0.0001
Voting Common Stock | Common Stock
Class of Stock [Line Items]
Number of shares issued			23,287,134	146,380
Issuance of common stock, net of offering cost/ ESPP plan			$ 2
Voting Common Stock | Public Offering
Class of Stock [Line Items]
Sale of stock price per share	$ 2
Voting Common Stock | Follow On Offering
Class of Stock [Line Items]
Number of shares issued	23,287,134
Voting Common Stock | ATM Program | Wedbush Securities, Inc.
Class of Stock [Line Items]
Issuance of common stock, net of offering cost/ ESPP plan		$ 75,000
Common stock, par value		$ 0.0001
Non-voting Common Stock
Class of Stock [Line Items]
Common stock, par value			$ 0.0001	$ 0.0001
Pre-Funded Warrants [Member]
Class of Stock [Line Items]
Common stock issuable upon exercise warrants			47,010,526
Warrants exercised			0
Warrant exercise price	$ 0.0001
Pre-Funded Warrants [Member] | Voting Common Stock
Class of Stock [Line Items]
Common stock issuable upon exercise warrants	47,010,526
Common stock price per warrant	$ 1.9999
Warrant exercise price	$ 0.0001

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Details) - USD ($)		12 Months Ended
	Jul. 15, 2021	Dec. 31, 2023	Dec. 31, 2022	Jul. 14, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 18,800,000
Weighted average period remaining (in years)		3 years 2 months 26 days
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend-yield assumption		$ 0
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock shares under the plan	3,278,048	4,523,924
Number of awards permitted to grant				0
Percentage of number of common stock issued and outstanding	4%
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock shares under the plan		589,344
Number of awards permitted to grant				0
Percentage of number of common stock issued and outstanding	1%
Common stock, Reserved for future issuance	254,390
2021 Employee Stock Purchase Plan | Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock issued		146,380	146,380

Stock Based Compensation - Summ

Stock Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 5,208	$ 4,551
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	2,876	1,626
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,332	$ 2,925

Stock Based Compensation - Su_2

Stock Based Compensation - Summary of Weighted-average for each of the Assumptions the Company Used to Determine the Grant-date Fair Value of Options Granted (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Risk free interest rate	3.95%	2.40%
Expected term (in years)	6 years 4 months 9 days	6 years 2 months 26 days
Expected dividend yield	0%	0%
Expected volatility of underlying common stock	87%	81%

Stock Based Compensation - Su_3

Stock Based Compensation - Summary of Stock Option Activity (Details) - Stock Options - 2018 and 2021 Equity Incentive Plans - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Options Outstanding, Beginning balance	5,230,537
Stock Options Outstanding, Granted	8,544,660
Stock Options Outstanding, Exercised	(316,441)
Stock Options Outstanding, Cancelled	(3,060,506)
Stock Options Outstanding, Ending balance	10,398,250	5,230,537
Stock Options vested or expected to vest	10,398,250
Stock options exercisable	1,765,282
Stock Options Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 5.35
Stock Options Granted, Weighted Average Exercise Price	2.70
Stock Options Exercised, Weighted Average Exercise Price	2.25
Stock Options Cancelled, Weighted Average Exercise Price	5.1
Stock Options Outstanding, Weighted Average Exercise Price, Ending balance	3.34	$ 5.35
Stock Options vested or expected to vest, Weighted Average Exercise Price	3.34
Stock options exercisable, Weighted Average Exercise Price	$ 4.88
Stock Options Outstanding, Weighted Average Remaining Contractual Life	8 years 10 months 13 days	8 years 5 months 26 days
Stock Options vested or expected to vest, Weighted Average Remaining Contractual Life	8 years 10 months 13 days
Stock options exercisable, Weighted Average Remaining Contractual Life	6 years 11 months 19 days
Stock Options Outstanding, Intrinsic Value, Ending	$ 28,278
Stock Options vested or expected to vest, Intrinsic Value	28,278
Stock options exercisable, Intrinsic Value	$ 3,016

Stock Based Compensation - Su_4

Stock Based Compensation - Summary of Other Information Related to Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Weighted-average fair value of options granted	$ 2.17	$ 2.80
Intrinsic value of options exercised	$ 152	$ 62

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the Federal Statutory Income Tax Rate to the Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Taxes at U.S. statutory rate	21%	21%
Changes from statutory rate:
State taxes, net of federal benefit	8.50%	8.30%
Tax credits	5.40%	5.10%
Share-based compensation	(0.70%)	(0.90%)
Change in valuation allowance	(34.10%)	(33.80%)
Other	(0.10%)	0.30%
Effective income tax rate	0%	0%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Tax Credit Carryforward [Line Items]
Effective tax rate	0%	0%
Taxes at U.S. statutory rate	21%	21%
Increase in valuation allowance	$ 30,400,000	$ 22,400,000
Accrued interest or penalties	$ 0	$ 0
Description of income tax examinations	the Company is subject to examination by these taxing authorities for all years since inception.
Massachusetts
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	$ 85,300,000
Net operating loss carryforwards, expiration year	2042
U.S. Federal
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	$ 84,800,000
U.S. Federal | R&D
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 11,700,000
Tax credit carryforwards, expiration year	2042
State | R&D
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 6,700,000
Tax credit carryforwards, expiration year	2037

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 23,201	$ 23,391
Tax credits	16,939	10,191
Deferred revenue	4,305	1,332
Depreciation and amortization	1,159	824
Amortization	479	525
Stock-based compensation	1,126	707
Leasehold liability	17,044	15,489
Capitalized R&D costs	31,515	14,380
Other	3,824	1,441
Total deferred tax assets	99,592	68,280
Deferred tax liabilities:
Right of use Asset	(17,346)	(16,411)
Valuation allowance	$ (82,246)	$ (51,869)

Collaboration and License Agr_2

Collaboration and License Agreements - Additional Information (Details) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	May 08, 2023	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2023	Dec. 31, 2022
Collaboration And License Agreements [Line Items]
Collaboration and license revenue				$ 21,049	$ 13,535
Incurred costs				114,507	80,171
Deferred revenue, current portion				10,137	$ 3,874
Long-term deferred revenue				$ 5,622
Maximum | Novartis Agreement
Collaboration And License Agreements [Line Items]
Ownership Interest				10%	10%
Minimum | Novartis Agreement
Collaboration And License Agreements [Line Items]
Ownership Interest		10%	10%
Amgen Inc. | Amgen Agreement
Collaboration And License Agreements [Line Items]
License agreement date	May 08, 2023
Upfront payment receivable	$ 30,000
Potential milestone payment	$ 500,000
Expects research term	3 years
Collaboration and license revenue				$ 14,200
Deferred revenue				15,800
Long-term deferred revenue				5,600
Novartis
Collaboration And License Agreements [Line Items]
License agreement date			Mar. 31, 2020
Upfront payment receivable		$ 20,000	$ 20,000
Collaboration and license revenue				5,800	$ 13,500
Reimbursement cost				$ 1,900	$ 4,500
Novartis | Research Funding
Collaboration And License Agreements [Line Items]
Upfront payment received			$ 10,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands			12 Months Ended
	Nov. 08, 2023 USD ($)	Jun. 30, 2018	Dec. 31, 2023 USD ($) Facility	Dec. 31, 2022 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Number of leases facilities | Facility			2
Operating lease, description			On November 8, 2023, the Company entered into a lease amendment extending the expiration date of the 830 Winter Street Lease from September 30, 2024 to October 31, 2029 and provides for one option to renew the 830 Winter Street Lease for a five-year period commencing on November 1, 2029, resulting in an increase in the lease liability of $6.2 million.
Lease security amount			$ 5,031	$ 5,037
Cash deposit			1,647	725
Lease costs			15,790	5,147
Right-of-use assets			63,492	59,102
Increase in lease liability	$ 6,200		62,386	56,694
Operating lease, renewal term	5 years
Operating lease commencing date	Nov. 01, 2029
cash payments for operating leases			$ 9,400	$ 2,000
Weighted-average remaining lease term (in years)			8 years 7 months 6 days	9 years 8 months 12 days
Operating lease weighted average incremental borrowing rate percent.			10.30%	9.80%
Royalty Agreement
Commitments And Contingencies Disclosure [Line Items]
Percentage of aggregate royalty of net sales of any product sold		1%
Minimum
Commitments And Contingencies Disclosure [Line Items]
Lease expiration date	Sep. 30, 2024
Maximum
Commitments And Contingencies Disclosure [Line Items]
Lease expiration date	Oct. 31, 2029
Letter of Credit
Commitments And Contingencies Disclosure [Line Items]
Lease security amount			$ 5,000

Commitments and Contingencies_2

Commitments and Contingencies - Summary Of Presentation Of Operating Lease In Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Nov. 08, 2023	Dec. 31, 2022
Assets [Abstract]
Operating lease assets	$ 63,492		$ 59,102
Liabilities [Abstract]
Operating lease liabilities, current	3,246		3,681
Operating lease liability, net of current portion	59,140		53,013
Total operating lease liabilities	$ 62,386	$ 6,200	$ 56,694

Commitment nad Contigencies - L

Commitment nad Contigencies - Lease Cost in the Company's Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Lease, Cost [Abstract]
Operating lease costs	$ 10,626	$ 3,264
Short-term lease costs	44	332
Variable lease costs	5,120	1,551
Total lease costs	$ 15,790	$ 5,147

Commitments and Contingencies_3

Commitments and Contingencies - Maturity of Future Payments Of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Nov. 08, 2023	Dec. 31, 2022
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2024	$ 9,507
2025	10,463
2026	10,944
2027	11,255
2028 and thereafter	53,734
Total future payments of operating lease liabilities	95,903
Less: imputed interest	(33,517)
Present value of operating lease liabilities	$ 62,386	$ 6,200	$ 56,694

Loan and Security Agreement - A

Loan and Security Agreement - Additional Information (Details) - USD ($)		12 Months Ended
	Sep. 09, 2022	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Debt instrument drew		$ 30,000,000
Interest rate		12.82%
Default interest rate	5%
Interest expense		$ 3,800,000	$ 1,200,000
K2 Health Ventures [Member]
Debt Instrument [Line Items]
Principal amount	$ 60,000,000
Facility fee	$ 400,000
Additional principal amount percentage	1%
Term loan maturity date	Sep. 01, 2026
Interest only payment term	24 months
Interest only payment extended term	36 months
Contractual interest rate	8.75%
Interest rate	9.90%	9.90%
Conversion price	$ 4.785
Final fee	6%
Covenant terms		During the term of the Loan Agreement, the Company must maintain minimum unrestricted cash and cash equivalents equal to 5.0 times the average monthly cash burn measured over the trailing three-month period.
K2 Health Ventures [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Prime rate	4.75%
Tranche One [Member] | K2 Health Ventures [Member]
Debt Instrument [Line Items]
Debt instrument drew	$ 30,000,000
Tranche Two [Member] | K2 Health Ventures [Member]
Debt Instrument [Line Items]
Debt instrument remaining borrowing capacity	10,000,000
Tranche Three [Member] | K2 Health Ventures [Member]
Debt Instrument [Line Items]
Debt instrument remaining borrowing capacity	$ 20,000,000
Maximum [Member] | K2 Health Ventures [Member]
Debt Instrument [Line Items]
Prepayment fee range	4%
Minimum [Member] | K2 Health Ventures [Member]
Debt Instrument [Line Items]
Prepayment fee range	1%
Covenant Terms, Unrestricted Cash and Cash Equivalents		$ 5,000,000

Loan and Security Agreement - S

Loan and Security Agreement - Schedule of Future Principal Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2024	$ 3,427
2025	14,588
2026	11,985
Total principal payments	30,000
Plus: Final payment fee	1,800
Less: unamortized debt discount and final fee	(1,753)
Total debt	30,047
Less: current portion of long-term debt	(3,347)
Long-term debt, net	$ 26,700	$ 29,290

Retirement Plan - Additional In

Retirement Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Defined contribution plan, employer contribution amount	$ 0.7	$ 0.6

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net loss	$ (89,218)	$ (66,221)
Weighted-average common shares outstanding, basic	65,599,858	24,048,267
Weighted-average common shares outstanding, diluted	65,599,858	24,048,267
Net loss per share, basic	$ (1.36)	$ (2.75)
Net loss per share, diluted	$ (1.36)	$ (2.75)

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details)	Dec. 31, 2023 shares
Pre-Funded Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock issuable upon exercise warrants	47,010,526

Net Loss Per Share - Summary _2

Net Loss Per Share - Summary of Potential Common Shares Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	16,667,842	7,347,317
Common stock issuable upon conversion of Loan Agreement
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	6,269,592	2,116,780
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	10,398,250	5,230,537