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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, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Risk free interest rate	4.03%	3.95%
Expected term (in years)	6 years 2 months 8 days	6 years 4 months 9 days
Expected dividend yield	0.00%	0.00%
Expected volatility of underlying common stock	89.00%	87.00%

Stock Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 9,549	$ 5,208
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	4,846	2,876
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 4,703	$ 2,332

- Definition

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

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+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2024

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, 2024 using:
	Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (Level 3)		Total
Assets
Cash equivalents – money market funds	$	169,744	$	-	$	-	$	169,744
Marketable securities – government securities		111,421		-		-		111,421
Total financial assets	$	281,165	$	-	$	-	$	281,165


	Fair value measurements at December 31, 2023 using:
	Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (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

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 convertible long-term debt was carried at amortized cost. The fair value of the convertible long-term debt was estimated to be $38.4 million at December 31, 2023. 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 Company's convertible long-term debt was extinguished on December 20, 2024.

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. Based on the borrowing rates currently available to the Company for bank loans with similar maturities, the fair value of long-term debt is approximately equal to its carrying amount as of December 31, 2024.

- Definition

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

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+ Details

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2024	Dec. 31, 2023
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
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	52,314,039	43,552,941
Common stock, shares outstanding	52,314,039	43,552,941
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	4,276,588
Common stock, shares outstanding	4,276,588	4,276,588

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (127,499)	$ (89,218)

- Definition

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

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-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Paragraph 1B
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Section S99
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Reference 32: http://www.xbrl.org/2003/role/disclosureRef
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Reference 33: http://www.xbrl.org/2003/role/disclosureRef
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Reference 34: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 35: http://www.xbrl.org/2003/role/disclosureRef
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Reference 36: http://www.xbrl.org/2003/role/disclosureRef
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Reference 37: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Maturity of Future Payments Of Operating Lease Liabilities

As of December 31, 2024, future payments of operating lease liabilities are as follows (in thousands):


	As of December 31, 2024
2025	$	10,089
2026		12,958
2027		13,329
2028		13,712
2029 and thereafter		43,994
Total future payments of operating lease liabilities		94,082
Less: imputed interest		(28,773	)
Present value of operating lease liabilities	$	65,309

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,
	2024		2023
Assets:
Operating lease assets	$	64,357	$	63,492

Liabilities:
Operating lease liabilities, current		4,570		3,246
Operating lease liabilities, net of current portion		60,739		59,140
Total operating lease liabilities	$	65,309	$	62,386

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,
	2024		2023
Operating lease costs	$	11,564	$	10,626
Short-term lease costs		-		44
Variable lease costs		3,408		5,120
Total lease costs	$	14,972	$	15,790

Loan and Security Agreements

12 Months Ended

Dec. 31, 2024

Debt Disclosure [Abstract]

Loan and Security Agreements

11. Loan and Security Agreements

K2 HealthVentures LLC

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 $60.0 million is available to the Company in three tranches, subject to certain terms and conditions. The Company drew the first tranche of $30.0 million from K2HV on the Closing Date. The Company had the option to draw the second tranche of $10.0 million upon the achievement of certain financial and clinical milestones and an uncommitted third tranche of $20.0 million could 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 loan was expected to mature on September 1, 2026 (the Maturity Date), and was subject to interest only payments for 24 months, which could be extended to 36 months upon achievement of certain financial and clinical milestones, following which the term loans would amortize in equal monthly installments until maturity. The Company had 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 accrued 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%.

On September 26, 2024, K2HV confirmed to the Company that the amortization commencement date would be October 1, 2025, thereby extending the interest-only period under the Loan Agreement for 12 months. This extension met the definition of an accounting debt modification in accordance with ASC 470-50 and was accounted for prospectively as a yield adjustment, with no resulting gain or loss recognized.

The lenders could 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 was convertible at the option of K2HV at a conversion price of $4.785 per share and future tranches could 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 met the derivative accounting scope exception since the embedded conversion option was indexed to the Company’s own common stock and qualifies for classification within stockholders’ equity.

The Company had 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 was 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 received 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 would be reduced to zero.

On November 20, 2024, K2HV elected to convert $15.0 million of the outstanding principal balance into 3,134,796 shares of the Company's voting common stock at a price of $4.785, in accordance with the agreement.

On December 20, 2024 the Company repaid the remaining obligation of the debt agreement, which included $15.0 million in remaining principal, a $1.8 million Exit Fee, and a $0.3 million prepayment fee. The Company recognized a loss from extinguishment of $1.1 million.

The Company recorded $3.6 million and $3.8 million in interest expense for the years ended December 31, 2024 and 2023, 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 12.61% upon extinguishment.

Silicon Valley Bank

On December 20, 2024 (the effective date), the Company entered into a Loan and Security Agreement (SVB Loan Agreement) with Silicon Valley Bank, a division of First-Citizens Bank & Trust Company (SVB). Under the SVB Loan Agreement, SVB will extend up to $52.5 million in a term loan facility, consisting of a first tranche of $32.5 million fully funded on the Effective Date and a second tranche of $20.0 million to be available to the Company at the Lender’s sole discretion on or prior to June 30, 2026.

The term loans will mature on September 1, 2029, and will be subject to monthly interest only payments until September 30, 2027, provided the Company achieves certain financial and clinical milestones, following which the term loans will amortize in equal monthly installments until maturity. If the Company does not achieve such financial and clinical milestones by June 30, 2026, the maturity date will be September 1, 2028, and the interest only period will end on September 30, 2026, following which the term loans will amortize in equal monthly installments until maturity.

The term loans will accrue interest at a per annum rate equal to the greater of (i) 7.00% and (ii) the prime rate (as last quoted in The Wall Street Journal), minus 0.75%; provided that such interest rate shall not exceed 9.75% per annum. The Company will be liable for a final payment that is due on the earliest to occur of (a) the maturity date, (b) the repayment of the term loans in full, and (c) the date upon which the term loans are accelerated by the Lender, in an amount equal to the aggregate original principal amount of the term loans extended by the Lender to the Company, multiplied by 5.0% (Exit Fee). In addition, the Company will be liable for a prepayment fee equal to (x) 3.0% of the principal amount of term loans prepaid during the first year of the term, (y) 2.0% of the principal amount of term loans prepaid during the second year of the term, and (z) 1.0% of the principal amount of term loans prepaid thereafter. The term loans will automatically accelerate upon the occurrence of a bankruptcy or insolvency event involving the Company or its subsidiaries.

The SVB Loan Agreement contains customary representations and warranties, events of default and affirmative and negative covenants, including covenants that limit or restrict the Company’s and its subsidiaries’ ability to, among other things, dispose of assets, make changes to its business, management, ownership or business locations, merge or consolidate, incur additional indebtedness, grant liens on its assets, pay dividends or other distributions, repurchase equity, make investments, and enter into certain transactions with affiliates, in each case subject to certain thresholds and exceptions. The New Loan Agreement does not require the Company to comply with a financial maintenance covenant. As collateral for its obligations under the New Loan Agreement, the Company granted the Lender a first-priority security interest on substantially all of the Company’s assets (other than intellectual property), subject to certain exceptions. The Company’s obligations under the SVB Loan Agreement will be guaranteed by each of the Company’s future direct or indirect subsidiaries, subject to certain exceptions.

The Company recorded $0.1 million in interest expense for the year ended December 31, 2024. The effective interest rate on the SVB Loan Agreement, including the amortization of the debt discount and issuance costs, and accretion of the Exit Fee, was 8.46% at December 31, 2024.

Future principal payments as of December 31, 2024 are as follows (in thousands):


2027	$	4,063
2028		16,250
2029		12,187
Total principal payments		32,500
Plus: Final payment fee		1,625
Less: unamortized debt discount and final fee		(2,053	)
Total debt		32,072

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
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-Section 50
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477092/405-40-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477092/405-40-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477092/405-40-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-Publisher FASB
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
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-Paragraph 1B
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
-Section S99
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-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/470/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 1B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1E

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1I
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1I

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
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-Section 50
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-Subparagraph (b)
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1I

+ Details

Commitments and Contingencies - Maturity of Future Payments Of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Oct. 28, 2024	Dec. 31, 2023	Nov. 08, 2023
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2025	$ 10,089
2026	12,958
2027	13,329
2028	13,712
2029 and thereafter	43,994
Total future payments of operating lease liabilities	94,082
Less: imputed interest	(28,773)
Present value of operating lease liabilities	$ 65,309	$ 6,100	$ 62,386	$ 6,200

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

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,
	2024			2023
Taxes at U.S. statutory rate		21.0	%		21.0	%
Changes from statutory rate:
State taxes, net of federal benefit		7.5	%		8.5	%
Tax credits		5.0	%		5.4	%
Share-based compensation		(0.9	)%		(0.7	)%
Change in valuation allowance		(30.9	)%		(34.1	)%
Other		(1.7	)%		(0.1	)%
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,
	2024			2023
Deferred tax assets:
Net operating loss carryforwards	$	31,332		$	23,201
Tax credits		25,427			16,939
Deferred revenue		3,536			4,305
Depreciation and amortization		1,216			1,159
Amortization		432			479
Stock-based compensation		1,681			1,126
Leasehold liability		17,842			17,044
Capitalized R&D costs		48,315			31,515
Other		9,391			3,824
Total deferred tax assets		139,172			99,592
Deferred tax liabilities:
Right of use Asset		(17,582	)		(17,346	)
Valuation allowance		(121,590	)		(82,246	)
Net deferred tax assets and liabilities	$	-		$	-

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, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Options Outstanding, Beginning balance	10,398,250
Stock Options Outstanding, Granted	3,501,849
Stock Options Outstanding, Exercised	(586,081)
Stock Options Outstanding, Cancelled	(846,236)
Stock Options Outstanding, Ending balance	12,467,782	10,398,250
Stock Options vested or expected to vest	12,467,782
Stock options exercisable	3,463,893
Stock Options Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 3.34
Stock Options Granted, Weighted Average Exercise Price	6.45
Stock Options Exercised, Weighted Average Exercise Price	2.93
Stock Options Cancelled, Weighted Average Exercise Price	3.52
Stock Options Outstanding, Weighted Average Exercise Price, Ending balance	4.22	$ 3.34
Stock Options vested or expected to vest, Weighted Average Exercise Price	4.22
Stock options exercisable, Weighted Average Exercise Price	$ 4.2
Stock Options Outstanding, Weighted Average Remaining Contractual Life	8 years 3 months 14 days	8 years 10 months 13 days
Stock Options vested or expected to vest, Weighted Average Remaining Contractual Life	8 years 3 months 14 days
Stock options exercisable, Weighted Average Remaining Contractual Life	7 years 3 months 25 days
Stock Options Outstanding, Intrinsic Value, Beginning	$ 28,278
Stock Options Outstanding, Intrinsic Value, Ending	3,912	$ 28,278
Stock Options vested or expected to vest, Intrinsic Value	3,912
Stock options exercisable, Intrinsic Value	$ 1,116

Segment Reporting - Schedule of Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Revenue
Collaboration and license revenue	$ 2,816	$ 21,049
Operating expenses:
Research and development	107,350	88,153
General and administrative	30,287	26,354
Loss from operations	(134,821)	(93,458)
Other (expense) income:
Interest and other income, net	12,065	7,999
Interest expense	3,653	3,759
Loss on extinguishment of debt	(1,090)
Net loss	(127,499)	(89,218)
Reportable Segment
Revenue
Collaboration and license revenue	2,816	21,049
Operating expenses:
Loss from operations	(134,821)	(93,458)
Other (expense) income:
Interest and other income, net	12,065	7,999
Interest expense	(3,653)	(3,759)
Loss on extinguishment of debt	(1,090)
Net loss	(127,499)	(89,218)
Reportable Segment \| Personnel Expenses
Operating expenses:
Research and development	31,742	24,165
General and administrative	10,900	9,065
Reportable Segment \| Laboratory Supplies, Research Materials and Studies
Operating expenses:
Research and development	31,468	30,101
Reportable Segment \| Clinical Studies
Operating expenses:
Research and development	19,245	10,214
Reportable Segment \| Legal and Professional Fees
Operating expenses:
General and administrative	7,380	7,119
Reportable Segment \| Facility-Related and Other
Operating expenses:
Research and development	16,669	16,298
General and administrative	6,576	6,976
Reportable Segment \| Stock-Based Compensation
Operating expenses:
Research and development	4,846	2,876
General and administrative	4,703	2,332
Reportable Segment \| Depreciation Expense
Operating expenses:
Research and development	3,380	4,499
General and administrative	$ 728	$ 862

Commitments and Contingencies - Summary Of Presentation Of Operating Lease In Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Oct. 28, 2024	Dec. 31, 2023	Nov. 08, 2023
Assets [Abstract]
Operating lease assets	$ 64,357		$ 63,492
Liabilities [Abstract]
Operating lease liabilities, current	4,570		3,246
Operating lease liability, net of current portion	60,739		59,140
Total operating lease liabilities	$ 65,309	$ 6,100	$ 62,386	$ 6,200

Retirement Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Retirement Benefits [Abstract]
Defined contribution plan, employer contribution amount	$ 1.0	$ 0.7

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2024

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, 2024 and 2023, 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. Unrealized gains on available-for-sale debt securities are reported as a component of accumulated other comprehensive loss in stockholders’ equity. 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 other income, net. 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 other income, net. 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, 2024 and 2023, the Company has not 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 that result from transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive income was unrealized gains on marketable securities.

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 November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-07, “Segment Reporting - Improvements to Reportable Segment Disclosures.” The ASU requires disclosure of incremental segment information on an annual and interim basis and also requires companies with a single reportable segment to provide all disclosures required by this ASU and all existing segment disclosures in Accounting Standard Codification (“ASC”) 280, “Segment Reporting.” The Company adopted this standard for this fiscal year ended December 31, 2024. The adoption of ASU 2023-07 did not have a material impact on the Company’s consolidated financial statements and related disclosures.

Recently Issued Accounting Pronouncements Not Yet Effective

In December 2023, the FASB issued ASU No. 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” This ASU updates income tax disclosure requirements primarily by requiring specific categories and greater disaggregation within the rate reconciliation and disaggregation of income taxes paid by jurisdiction. This ASU is effective for annual periods beginning after December 15, 2024, and is applicable to the Company’s fiscal year beginning January 1, 2025, with early application permitted. The Company is currently evaluating the impact of adopting this ASU on its consolidated financial statements and disclosures.

In November 2024, the FASB issued Accounting Standards Update (ASU) 2024-04, Debt-Debt with Conversions and Other Options. ASU 2024-04 is intended to clarify requirements for determining whether certain settlements of convertible debt instruments, including convertible debt instruments with cash conversion features or convertible debt instruments that are not currently convertible, should be accounted for as an induced conversion. This ASU is effective for all entities for annual reporting periods beginning after

December 15, 2025, and interim reporting periods within those annual reporting periods, with early adoption permitted. The Company is currently evaluating the potential impact of this guidance on its disclosures.

In November 2024, the FASB issued Accounting Standards Update (ASU) 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures. ASU 2024-03 is intended to improve disclosures about a public business entity’s expense and provide more detailed information to investors about the types of expenses in commonly presented expense captions. The amendments in this ASU are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the potential impact of this guidance on its disclosures.

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, 2024	Dec. 31, 2023
Earnings Per Share [Abstract]
Net loss	$ (127,499)	$ (89,218)
Weighted-average common shares outstanding, basic	111,990,417	65,599,858
Weighted-average common shares outstanding, diluted	111,990,417	65,599,858
Net loss per share, basic	$ (1.14)	$ (1.36)
Net loss per share, diluted	$ (1.14)	$ (1.36)

- Definition

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

+ References

+ Details

- Definition

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

+ References

+ Details

- Definition

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

+ References

+ Details

Retirement Plan

12 Months Ended

Dec. 31, 2024

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 $1.0 million and $0.7 million for the years ended December 31, 2024 and 2023, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147480266/715-60-50-3

+ Details

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Cash flows from operating activities:
Net loss	$ (127,499)	$ (89,218)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	4,108	5,361
Accretion of marketable securities	(3,897)	(1,072)
Non-cash interest expense related to loan payable	773	757
Loss on extinguishment of debt	1,090
Stock-based compensation	9,549	5,208
Changes in current assets and liabilities:
Prepaid expenses and other assets	(538)	985
Right-of-use assets and lease liabilities, net	1,881	935
Accounts payable	1,994	(52)
Accrued expense and other liabilities	4,532	3,853
Deferred revenue	(2,815)	11,885
Net cash used in operating activities	(110,822)	(61,358)
Cash flows from investing activities:
Purchases of property and equipment	(3,825)	(3,146)
Purchases of marketable securities	(241,445)	(77,613)
Proceeds from maturities of marketable securities	192,657	20,000
Net cash used in investing activities	(52,613)	(60,759)
Cash flows from financing activities:
Repayment of loan payable, net	(17,144)
Proceeds from borrowings under loan agreement, net	32,457
Proceeds from issuance of common stock, net of offering costs	33,131	42,414
Proceeds from issuance of pre-funded warrants, net of offering costs	158,271	92,318
Issuance of common stock under employee stock purchase plan	333
Proceeds from exercise of stock options	1,717	711
Net cash provided by financing activities	208,765	135,443
Net increase in cash, cash equivalents and restricted cash	45,330	13,326
Cash, cash equivalents, and restricted cash - beginning of year	138,390	125,064
Cash, cash equivalents, and restricted cash - end of year	183,720	138,390
Summary of cash, cash equivalents and restricted cash reported within the consolidated balance sheets:
Cash and cash equivalents	178,689	133,359
Restricted cash	5,031	5,031
Total cash, cash equivalents, and restricted cash	183,720	138,390
Supplemental disclosure of cash flow information:
Cash paid for interest	2,881	3,002
Supplemental disclosure of non-cash investing and financing activities:
Debt issuance costs not yet paid	400
Financing costs not yet paid	200
Lease liability arising from obtaining right-of-use asset	6,133	6,214
Purchase of property and equipment in accounts payable and accrued liabilities	84	$ 301
Issuance of common stock upon note conversion	$ 14,750

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2024

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

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 Other Comprehensive Loss	Accumulated Deficit
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
Exercise of stock options	711					711
Exercise of stock options, shares				316,441
Issuance of common stock, net of offering costs	42,414			$ 2		42,412
Issuance of common stock, net of offering costs, 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
Exercise of stock options	1,717					1,717
Exercise of stock options, shares				586,081
Issuance of common stock under employee stock purchase plan	333					333
Issuance of common stock under employee stock purchase plan, shares				82,153
Issuance of common stock, net of offering costs	33,131			$ 1		33,130
Issuance of common stock, net of offering costs, shares				4,958,068
Issuance of pre-funded warrants, net of offering costs	158,071					158,071
Conversion of convertible debt	14,750					14,750
Conversion of convertible debt, shares				3,134,796
Stock-based compensation expense	9,549					9,549
Net loss	(127,499)							(127,499)
Unrealized gain on available-for-sale securities	51						$ 51
Balances at Dec. 31, 2024	$ 240,970			$ 5	$ 1	$ 616,009	$ 51	$ (375,096)
Balances, shares at Dec. 31, 2024		52,314,039	4,276,588	52,314,039	4,276,588

Income Taxes

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Income Taxes

8. Income Taxes

During the years ended December 31, 2024 and 2023, 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,
	2024			2023
Taxes at U.S. statutory rate		21.0	%		21.0	%
Changes from statutory rate:
State taxes, net of federal benefit		7.5	%		8.5	%
Tax credits		5.0	%		5.4	%
Share-based compensation		(0.9	)%		(0.7	)%
Change in valuation allowance		(30.9	)%		(34.1	)%
Other		(1.7	)%		(0.1	)%
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,
	2024			2023
Deferred tax assets:
Net operating loss carryforwards	$	31,332		$	23,201
Tax credits		25,427			16,939
Deferred revenue		3,536			4,305
Depreciation and amortization		1,216			1,159
Amortization		432			479
Stock-based compensation		1,681			1,126
Leasehold liability		17,842			17,044
Capitalized R&D costs		48,315			31,515
Other		9,391			3,824
Total deferred tax assets		139,172			99,592
Deferred tax liabilities:
Right of use Asset		(17,582	)		(17,346	)
Valuation allowance		(121,590	)		(82,246	)
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, 2024, the Company maintains a full valuation allowance against its net deferred tax assets. The valuation allowance increased by $39.3 million and $30.4 million during the years ended December 31, 2024 and 2023, respectively.

As of December 31, 2024, the Company had U.S. federal net operating loss carryforwards of approximately $113.6 million. The U.S. federal net operating losses have an indefinite life carryforward. As of December 31, 2024, the Company had Massachusetts net operating loss carryforwards of approximately $118.3 million that expire at various dates through 2043. As of December 31, 2024, the Company had U.S. R&D federal credit carryforwards of approximately $17.9 million that expire at various dates through 2043. As of December 31, 2024, the Company had U.S. state R&D tax credit carryforwards of approximately $9.5 million that expire at various dates through 2038.

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 is 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, 2024 and 2023, 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, 2024, the Company is subject to examination by these taxing authorities for all years since inception.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
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-Name Accounting Standards Codification
-Section 55
-Paragraph 231
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147477891/740-270-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Loan and Security Agreements - Additional Information (Details) - USD ($)					12 Months Ended
	Dec. 20, 2024	Nov. 20, 2024	Sep. 26, 2024	Sep. 09, 2022	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Debt instrument drew					$ 32,500,000
Rcognized loss from extinguishment					$ (1,090,000)
K2HV [Member]
Debt Instrument [Line Items]
Principal amount				$ 60,000,000
Facility fee				$ 400,000
Additional principal amount percentage				1.00%
Term loan maturity date				Sep. 01, 2026
Interest only payment term				24 months
Interest only payment extended term			12 months	36 months
Contractual interest rate				8.75%
Prime rate				4.75%
Interest rate				9.90%	12.61%
Conversion price		$ 4.785		$ 4.785
Repaid remaining principal amount	$ 15,000,000
Exit fee	1,800,000
Prepayment fee	300,000
Rcognized loss from extinguishment	(1,100,000)
Final fee				6.00%
Convertible outstanding principal balance		$ 15,000,000
Converted instrument, shares issued		3,134,796
Interest expense					$ 3,600,000	$ 3,800,000
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Principal amount	$ 52,500,000
Term loan maturity date	Sep. 01, 2029
Contractual interest rate	7.00%
Prime rate	0.75%
Interest rate					8.46%
Final fee	5.00%
Percentage of loan prepayment fee in first year	3.00%
Percentage of loan prepayment fee in year two	2.00%
Percentage of loan prepayment fee in there after year two	1.00%
Debt instrument payment, description					The term loans will mature on September 1, 2029, and will be subject to monthly interest only payments until September 30, 2027, provided the Company achieves certain financial and clinical milestones, following which the term loans will amortize in equal monthly installments until maturity. If the Company does not achieve such financial and clinical milestones by June 30, 2026, the maturity date will be September 1, 2028, and the interest only period will end on September 30, 2026, following which the term loans will amortize in equal monthly installments until maturity.
Interest expense					$ 100,000
Tranche One [Member] \| K2HV [Member]
Debt Instrument [Line Items]
Debt instrument drew				$ 30,000,000
Tranche One [Member] \| Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Debt instrument drew	$ 32,500,000
Tranche Two [Member] \| K2HV [Member]
Debt Instrument [Line Items]
Debt instrument remaining borrowing capacity				10,000,000
Tranche Two [Member] \| Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Debt instrument remaining borrowing capacity	$ 20,000,000
Tranche Three [Member] \| K2HV [Member]
Debt Instrument [Line Items]
Debt instrument remaining borrowing capacity				$ 20,000,000
Maximum [Member] \| K2HV [Member]
Debt Instrument [Line Items]
Prepayment fee range				4.00%
Maximum [Member] \| Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Contractual interest rate	9.75%
Minimum [Member] \| K2HV [Member]
Debt Instrument [Line Items]
Prepayment fee range				1.00%

Net Loss Per Share - Additional Information (Details) - shares	Dec. 31, 2024	Dec. 27, 2024
Pre-Funded Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock issuable upon exercise warrants	73,087,945	7,500,000

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands					12 Months Ended		20 Months Ended
	Dec. 27, 2024	Apr. 24, 2024	Jun. 01, 2023	May 16, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024
Class of Stock [Line Items]
Issuance of common stock, net of offering costs					$ 33,131	$ 42,414
Net proceeds from common stock and warrants after deducting underwriting discounts, commissions and other offering expenses		$ 161,400	$ 134,700
Proceeds from issuance of pre-funded warrants, net of offering costs		128,300	92,300		158,271	92,318
Proceeds from issuance of common stock, net of offering costs		33,100	42,400		33,131	42,414
Proceeds from issuance of pre-funded warrants, net of offering costs		$ 128,300	$ 92,300		$ 158,271	$ 92,318
Voting Common Stock
Class of Stock [Line Items]
Common stock, par value					$ 0.0001	$ 0.0001	$ 0.0001
Voting Common Stock \| Common Stock
Class of Stock [Line Items]
Number of shares issued					4,958,068	23,287,134
Issuance of common stock, net of offering costs					$ 1	$ 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		4,958,068	23,287,134
Sale of stock price per share		$ 7.13
Underwriter option to purchase number of additional shares		2,485,487
Voting Common Stock \| ATM Program \| Wedbush Securities, Inc.
Class of Stock [Line Items]
Number of shares issued							0
Issuance of common stock, net of offering costs				$ 75,000
Common stock, par value				$ 0.0001
Pre-Funded Warrants [Member]
Class of Stock [Line Items]
Common stock issuable upon exercise warrants	7,500,000				73,087,945		73,087,945
Warrants exercised					0		0
Warrant exercise price			$ 0.0001
Proceeds from issuance of pre-funded warrants, net of offering costs	$ 30,000
Proceeds from issuance of pre-funded warrants, net of offering costs	30,000
Offering expenses	$ 200
Pre-Funded Warrants [Member] \| Voting Common Stock
Class of Stock [Line Items]
Common stock issuable upon exercise warrants		18,577,419	47,010,526
Common stock price per warrant	$ 4	$ 7.1299	$ 1.9999
Warrant exercise price	$ 0.0001	$ 0.0001	$ 0.0001

Stock Based Compensation - Additional Information (Details) - USD ($)		12 Months Ended
	Jul. 15, 2021	Dec. 31, 2024	Dec. 31, 2023	Jul. 14, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 24,000,000
Weighted average period remaining (in years)		2 years 7 months 28 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	5,781,492
Number of awards permitted to grant				0
Percentage of number of common stock issued and outstanding	4.00%
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock shares under the plan		985,486
Number of awards permitted to grant				0
Percentage of number of common stock issued and outstanding	1.00%
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		228,533	146,380

Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
Document and Entity Information - USD ($) $ in Thousands	Dec. 31, 2024	Feb. 28, 2025	Jun. 30, 2024
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2024
Document Fiscal Year Focus	2024
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			$ 201,649,026
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	34
Documents Incorporated by Reference [Text Block]	DOCUMENTS INCORPORATED BY REFERENCE None.
Auditor Opinion [Text Block]	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of TScan Therapeutics, Inc. and subsidiary (the "Company") as of December 31, 2024 and 2023, the related consolidated statements of operations and comprehensive loss, stockholders' equity, and cash flows for the years then ended, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2024, in conformity with accounting principles generally accepted in the United States of America.
Voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		52,314,039
Non-voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		4,276,588

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

Basis of Presentation

Principles of Consolidation

Use of Estimates

Cash and Cash Equivalents

Restricted Cash

Marketable Securities

Concentrations of Credit Risk

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

Impairment of Long-Lived Assets

Fair Value Measurements

•

Level 1—Unadjusted quoted prices in active markets that are accessible to the reporting entity at the measurement date for identical assets and liabilities.

•

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

•

Leases

Research and Development Costs

Accrued Research and Manufacturing Contract Costs

Patent Costs

Revenue Recognition

(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.

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.

Comprehensive Loss

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.

Recently Adopted Accounting Pronouncements/ Recently Issued Accounting Pronouncements Not Yet Effective

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements Not Yet Effective

Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 4.1	$ 5.4

Loan and Security Agreements - Schedule of Future Principal Payments (Details) $ in Thousands	Dec. 31, 2024 USD ($)
Debt Disclosure [Abstract]
2027	$ 4,063
2028	16,250
2029	12,187
Total principal payments	32,500
Plus: Final payment fee	1,625
Less: unamortized debt discount and final fee	(2,053)
Total debt	$ 32,072

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Income Taxes - Reconciliation of the Federal Statutory Income Tax Rate to the Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Taxes at U.S. statutory rate	21.00%	21.00%
Changes from statutory rate:
State taxes, net of federal benefit	7.50%	8.50%
Tax credits	5.00%	5.40%
Share-based compensation	(0.90%)	(0.70%)
Change in valuation allowance	(30.90%)	(34.10%)
Other	(1.70%)	(0.10%)
Effective income tax rate	0.00%	0.00%

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2024

Share-Based Payment Arrangement [Abstract]

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, 2024 and 2023 was classified in the consolidated statement of operations as follows (in thousands):


	Year Ended December 31,
	2024		2023
Research and development	$	4,846	$	2,876
General and administrative		4,703		2,332
Total stock-based compensation expense	$	9,549	$	5,208

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,
	2024			2023
Risk free interest rate		4.03	%		3.95	%
Expected term (in years)		6.19			6.36
Expected dividend yield		0	%		0	%
Expected volatility of underlying common stock		89	%		87	%

Summary of Stock Option Activity

The following table summarizes the stock option activity:


	Stock Options			Weighted Average Exercise Price		Weighted Average Remaining Life (in Years)		Intrinsic Value (in thousands)
Outstanding January 1, 2024		10,398,250		$	3.34		8.87	$	28,278
Granted		3,501,849			6.45
Exercised		(586,081	)		2.93
Canceled		(846,236	)		3.52
Outstanding December 31, 2024		12,467,782		$	4.22		8.29	$	3,912
Options vested or expected to vest as of December 31, 2024		12,467,782		$	4.22		8.29	$	3,912
Stock options exercisable as of December 31, 2024		3,463,893		$	4.20		7.32	$	1,116

Summary of Other Information Related to Option Activity

Other information related to the option activity for the years ended December 31, 2024 and 2023:


	Year Ended December 31,
	2024		2023
Weighted-average fair value of options granted	$	4.90	$	2.17
Intrinsic value of options exercised (in thousands)		1,954		152

Nature of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Date of incorporation	Apr. 17, 2018
Net losses	$ 127,499	$ 89,218
Accumulated deficit	$ 375,096	$ 247,597

- Definition

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

+ References

+ Details

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2024

Segment Reporting [Abstract]

Schedule of Segment Information

The following table provides information about the Company's single operating segment which includes significant expenses by function along with significant non-cash expense items.


	Year Ended December 31,
	2024			2023
Revenue:
Collaboration and license revenue		2,816			21,049
Operating expenses:
Research and development:
Personnel expenses		31,742			24,165
Laboratory supplies, research materials and studies		31,468			30,101
Clinical studies		19,245			10,214
Facility-related and other		16,669			16,298
Stock-based compensation		4,846			2,876
Depreciation expense		3,380			4,499
General and administrative:
Personnel expenses		10,900			9,065
Legal and professional fees		7,380			7,119
Facility-related and other		6,576			6,976
Stock-based compensation		4,703			2,332
Depreciation Expense		728			862
Loss from operations		(134,821	)		(93,458	)
Other (expense) income:
Interest and other income, net		12,065			7,999
Interest expense		(3,653	)		(3,759	)
Loss on extinguishment of debt		(1,090	)		-
Net Loss		(127,499	)		(89,218	)

Collaboration and License Agreements

12 Months Ended

Dec. 31, 2024

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, 2024 and 2023 the Company recognized $2.8 million and $14.2 million, respectively, of revenue associated with the Amgen Agreement. As of December 31, 2024, the Company recorded $12.9 million of deferred revenue, of which $1.2 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, 2024 and 2023, 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 year ended December 31, 2023 the Company recognized $5.8 million of revenue associated with the Novartis Agreement, of which $1.9 million 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

12 Months Ended

Dec. 31, 2024

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.

On October 28, 2024, the Company entered into a second lease amendment expanding the rentable space of 830 Winter Street. The amendment provides for an additional 25,628 square feet of space with a commencement date of December 1, 2024 and an expiration date of October 31, 2029 with one option to review for a five-year period. This amendment resulted in an increase in the lease liability of $6.1 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,
	2024		2023
Assets:
Operating lease assets	$	64,357	$	63,492

Liabilities:
Operating lease liabilities, current		4,570		3,246
Operating lease liabilities, net of current portion		60,739		59,140
Total operating lease liabilities	$	65,309	$	62,386

The following table summarizes the effect of lease costs in the Company's consolidated statement of operations (in thousands):


	Years Ended December 31,
	2024		2023
Operating lease costs	$	11,564	$	10,626
Short-term lease costs		-		44
Variable lease costs		3,408		5,120
Total lease costs	$	14,972	$	15,790

During the years ended December 31, 2024 and 2023, the Company made cash payments for operating leases of $9.8 million and $9.4 million, respectively.

As of December 31, 2024, future payments of operating lease liabilities are as follows (in thousands):


	As of December 31, 2024
2025	$	10,089
2026		12,958
2027		13,329
2028		13,712
2029 and thereafter		43,994
Total future payments of operating lease liabilities		94,082
Less: imputed interest		(28,773	)
Present value of operating lease liabilities	$	65,309

As of December 31, 2024, the weighted average remaining lease term was 7.3 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 10.0%. 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%.

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.

Segment Reporting

12 Months Ended

Dec. 31, 2024

Segment Reporting [Abstract]

Segment Reporting

13. Segment Reporting

Operating segments are defined as components of the entity for which separate financial information is made available and that is regularly evaluated by the chief operating decision maker (CODM) in making decisions regarding resource allocation and assessing performance. The Company's CODM is its chief executive officer and the Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company is focused on the development of T cell receptor (TCR)-engineered T cell (TCR-T) therapies for the treatment of patients with cancer.

The CODM assesses the Company's performance by reviewing GAAP net loss and significant expenses by function along with the annual budget. The chief operating decision maker considers budget-to-actual variances on a quarterly basis when making decisions about the allocation of operating and capital resources.

The following table provides information about the Company's single operating segment which includes significant expenses by function along with significant non-cash expense items.


	Year Ended December 31,
	2024			2023
Revenue:
Collaboration and license revenue		2,816			21,049
Operating expenses:
Research and development:
Personnel expenses		31,742			24,165
Laboratory supplies, research materials and studies		31,468			30,101
Clinical studies		19,245			10,214
Facility-related and other		16,669			16,298
Stock-based compensation		4,846			2,876
Depreciation expense		3,380			4,499
General and administrative:
Personnel expenses		10,900			9,065
Legal and professional fees		7,380			7,119
Facility-related and other		6,576			6,976
Stock-based compensation		4,703			2,332
Depreciation Expense		728			862
Loss from operations		(134,821	)		(93,458	)
Other (expense) income:
Interest and other income, net		12,065			7,999
Interest expense		(3,653	)		(3,759	)
Loss on extinguishment of debt		(1,090	)		-
Net Loss		(127,499	)		(89,218	)

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Stockholders' Equity

12 Months Ended

Dec. 31, 2024

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 under a registration statement on Form S-3 (File No. 333-268260) filed with the SEC, which was declared effective on May 16, 2023. No Voting Common Stock has been sold under this Sales Agreement to date.

Equity Offerings

On June 1, 2023, the Company completed an underwritten public offering resulting in the issuance and sale of (a) 23,287,134 shares of Voting Common Stock, at a price of $2.00 per share, and (b) pre-funded warrants (Pre-Funded Warrants) to purchase up to 47,010,526 shares of the Voting Common Stock, at a price of $1.9999 per warrant with an exercise price of $0.0001 per share. 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.

On April 24, 2024, the Company completed an underwritten public offering resulting in the issuance and sale of (a) 4,958,068 shares of Voting Common Stock, including the partial exercise of the underwriters’ option to purchase 2,485,487 additional shares of Voting Common Stock, at the closing market price on April 16, 2024, of $7.13 per share, and (b) Pre-Funded Warrants to purchase up to 18,577,419 shares of the Voting Common Stock, at a price of $7.1299 per warrant with an exercise price of $0.0001 per share. The Company received aggregate net proceeds of approximately $161.4 million after deducting underwriting discounts, commissions and other offering expenses, with $33.1 million allocated to the Voting Common Stock and $128.3 million allocated to Pre-Funded Warrants.

On December 27, 2024, the Company completed a registered direct offering with an existing investor for the issuance of pre-funded warrants to purchase up to 7,500,000 shares of the Company's Voting Common Stock, with an exercise price of $0.0001 per warrant. The pre-funded warrants were issued at a purchase price of $4.00 per warrant, resulting in gross proceeds of approximately $30.0 million, before deducting offering expenses of $0.2 million.

The Pre-Funded Warrants are immediately exercisable subject to certain ownership limitations, have an exercise price of $0.0001 per share, may be exercised at any time and do not expire. The Pre-Funded Warrants were determined to be equity classified because they are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, permit the holders to receive a fixed number of common shares upon exercise, are indexed to the Company’s common stock and meet the equity classification criteria. In

addition, the Pre-Funded Warrants do not provide any guarantee of value or return. 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, 2024, no Pre-Funded Warrants have been exercised.

- Definition

The entire disclosure for equity.

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+ Details

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Tax Credit Carryforward [Line Items]
Effective tax rate	0.00%	0.00%
Taxes at U.S. statutory rate	21.00%	21.00%
Increase in valuation allowance	$ 39,300,000	$ 30,400,000
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	$ 118,300,000
Net operating loss carryforwards, expiration year	2043
U.S. Federal
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	$ 113,600,000
U.S. Federal \| R&D
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 17,900,000
Tax credit carryforwards, expiration year	2043
State \| R&D
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 9,500,000
Tax credit carryforwards, expiration year	2038

Commitments and Contingencies - Additional Information (Details) $ in Thousands				12 Months Ended
	Oct. 28, 2024 USD ($) ft²	Nov. 08, 2023 USD ($)	Jun. 30, 2018	Dec. 31, 2024 USD ($) Facility	Dec. 31, 2023 USD ($)
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.On October 28, 2024, the Company entered into a second lease amendment expanding the rentable space of 830 Winter Street. The amendment provides for an additional 25,628 square feet of space with a commencement date of December 1, 2024 and an expiration date of October 31, 2029 with one option to review for a five-year period. This amendment resulted in an increase in the lease liability of $6.1 million.
Lease expiration date	Oct. 31, 2029
Lease security amount				$ 5,031	$ 5,031
Cash deposit				1,766	1,647
Lease costs				14,972	15,790
Right-of-use assets				64,357	63,492
Increase in lease liability	$ 6,100	$ 6,200		65,309	62,386
Operating lease, renewal term	5 years	5 years
Lease space for facility \| ft²	25,628
Operating lease commencing date	Dec. 01, 2024	Nov. 01, 2029
cash payments for operating leases				$ 9,800	$ 9,400
Weighted-average remaining lease term (in years)				7 years 3 months 18 days	8 years 7 months 6 days
Operating lease weighted average incremental borrowing rate percent.				10.00%	10.30%
Royalty Agreement
Commitments And Contingencies Disclosure [Line Items]
Percentage of aggregate royalty of net sales of any product sold			1.00%
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

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2024

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,
	2024		2023
Accrued employee compensation and benefits	$	6,845	$	5,478
Accrued research and development		6,735		3,537
Accrued consulting and professional services		1,473		1,026
Accrued legal services and license fee		281		250
Other		76		425
Total accrued expenses and other current liabilities	$	15,410	$	10,716

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, 2024	Dec. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	12,605,915	16,667,842
Potential shares issuable under the ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	138,133
Common stock issuable upon conversion of Loan Agreement
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total		6,269,592
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	12,467,782	10,398,250

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2024

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment

Property and equipment consist of the following (in thousands):


	December 31,
	2024			2023
Laboratory equipment	$	19,371		$	15,653
Leasehold improvements		3,258			3,159
Furniture and fixtures		1,721			1,519
Office and computer equipment		1,496			1,460
Construction-in-progress		100			548
Property and equipment		25,946		$	22,339
Less: accumulated depreciation and amortization		(18,704	)		(14,597	)
Property and equipment, net	$	7,242		$	7,742

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2024

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, 2024 using:
	Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (Level 3)		Total
Assets
Cash equivalents – money market funds	$	169,744	$	-	$	-	$	169,744
Marketable securities – government securities		111,421		-		-		111,421
Total financial assets	$	281,165	$	-	$	-	$	281,165


	Fair value measurements at December 31, 2023 using:
	Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (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

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued employee compensation and benefits	$ 6,845	$ 5,478
Accrued research and development	6,735	3,537
Accrued consulting and professional services	1,473	1,026
Accrued legal services and license fee	281	250
Other	76	425
Total accrued expenses and other current liabilities	$ 15,410	$ 10,716

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
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
Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of convertible long-term debt		$ 38,400

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 178,689	$ 133,359
Marketable securities	111,421	58,685
Prepaid expenses and other current assets	2,612	2,193
Total current assets	292,722	194,237
Property and equipment, net	7,242	7,742
Right-of-use assets	64,357	63,492
Restricted cash	5,031	5,031
Long-term deposit and other assets	1,766	1,647
Total assets	371,118	272,149
Current liabilities:
Accounts payable	4,278	2,374
Accrued expenses and other current liabilities	15,410	10,716
Operating lease liability, current portion	4,570	3,246
Deferred revenue, current portion	11,698	10,137
Current portion of long-term debt		3,347
Total current liabilities	35,956	29,820
Deferred revenue, net of current portion	1,246	5,622
Operating lease liability, net of current portion	60,739	59,140
Long-term debt and accrued interest	32,072	26,700
Other long term liabilities	135
Total liabilities	130,148	121,282
Commitments and contingencies (Note 10)
Stockholders' equity (deficit):
Preferred Stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding at December 31, 2024 and 2023	0	0
Additional paid-in capital	616,009	398,459
Accumulated other comprehensive income	51
Accumulated deficit	(375,096)	(247,597)
Total stockholders' equity	240,970	150,867	$ 99,434
Total liabilities and stockholders' equity	371,118	272,149
Voting Common Stock
Stockholders' equity (deficit):
Common stock	5	4
Non-voting Common Stock
Stockholders' equity (deficit):
Common stock	$ 1	$ 1

Commitment nad Contigencies - Lease Cost in the Company's Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Lease, Cost [Abstract]
Operating lease costs	$ 11,564	$ 10,626
Short-term lease costs		44
Variable lease costs	3,408	5,120
Total lease costs	$ 14,972	$ 15,790

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2024

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,
	2024		2023
Accrued employee compensation and benefits	$	6,845	$	5,478
Accrued research and development		6,735		3,537
Accrued consulting and professional services		1,473		1,026
Accrued legal services and license fee		281		250
Other		76		425
Total accrued expenses and other current liabilities	$	15,410	$	10,716

Stock Based Compensation

12 Months Ended

Dec. 31, 2024

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 governed 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, 2024, there were 5,781,492 shares 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 number of the total outstanding common shares 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, 2024 and 2023, there were 228,533 and 146,380 shares issued under the 2021 ESPP, respectively. As of December 31, 2024, there were 985,486 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


	Year Ended December 31,
	2024		2023
Research and development	$	4,846	$	2,876
General and administrative		4,703		2,332
Total stock-based compensation expense	$	9,549	$	5,208

Stock 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 not 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,
	2024			2023
Risk free interest rate		4.03	%		3.95	%
Expected term (in years)		6.19			6.36
Expected dividend yield		0	%		0	%
Expected volatility of underlying common stock		89	%		87	%

The following table summarizes the stock option activity:


	Stock Options			Weighted Average Exercise Price		Weighted Average Remaining Life (in Years)		Intrinsic Value (in thousands)
Outstanding January 1, 2024		10,398,250		$	3.34		8.87	$	28,278
Granted		3,501,849			6.45
Exercised		(586,081	)		2.93
Canceled		(846,236	)		3.52
Outstanding December 31, 2024		12,467,782		$	4.22		8.29	$	3,912
Options vested or expected to vest as of December 31, 2024		12,467,782		$	4.22		8.29	$	3,912
Stock options exercisable as of December 31, 2024		3,463,893		$	4.20		7.32	$	1,116

Other information related to the option activity for the years ended December 31, 2024 and 2023:


	Year Ended December 31,
	2024		2023
Weighted-average fair value of options granted	$	4.90	$	2.17
Intrinsic value of options exercised (in thousands)		1,954		152

As of December 31, 2024, the unrecognized compensation cost related to outstanding options was $24.0 million, which is expected to be recognized over a weighted-average period of 2.66 years.

Property and Equipment

12 Months Ended

Dec. 31, 2024

Property, Plant and Equipment [Abstract]

Property and Equipment

3. Property and Equipment

Property and equipment consist of the following (in thousands):


	December 31,
	2024			2023
Laboratory equipment	$	19,371		$	15,653
Leasehold improvements		3,258			3,159
Furniture and fixtures		1,721			1,519
Office and computer equipment		1,496			1,460
Construction-in-progress		100			548
Property and equipment		25,946		$	22,339
Less: accumulated depreciation and amortization		(18,704	)		(14,597	)
Property and equipment, net	$	7,242		$	7,742

Depreciation and amortization expense for the years ended December 31, 2024 and 2023 was $4.1 million and $5.4 million, respectively.

Net Loss Per Share

12 Months Ended

Dec. 31, 2024

Earnings Per Share [Abstract]

Net Loss Per Share

14. 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,
	2024			2023
Numerator:
Net loss	$	(127,499	)	$	(89,218	)
Denominator:
Weighted-average common shares outstanding, basic and diluted		111,990,417			65,599,858
Net loss per share, basic and diluted	$	(1.14	)	$	(1.36	)

The 73,087,945 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,
	2024		2023
Options to purchase common stock		12,467,782		10,398,250
Potential shares issuable under the ESPP		138,133		-
Common stock issuable upon conversion of Loan Agreement		-		6,269,592
Total		12,605,915		16,667,842

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2024

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,
	2024			2023
Numerator:
Net loss	$	(127,499	)	$	(89,218	)
Denominator:
Weighted-average common shares outstanding, basic and diluted		111,990,417			65,599,858
Net loss per share, basic and diluted	$	(1.14	)	$	(1.36	)

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,
	2024		2023
Options to purchase common stock		12,467,782		10,398,250
Potential shares issuable under the ESPP		138,133		-
Common stock issuable upon conversion of Loan Agreement		-		6,269,592
Total		12,605,915		16,667,842

Segment Reporting - Additional Information (Details)	12 Months Ended
Segment Reporting - Additional Information (Details)	Dec. 31, 2024 Segment
Segment Reporting [Abstract]
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	srt:ChiefExecutiveOfficerMember
Number of operating segments	1
Segment reporting, CODM, profit (loss) measure, how used, description	The CODM assesses the Company's performance by reviewing GAAP net loss and significant expenses by function along with the annual budget. The chief operating decision maker considers budget-to-actual variances on a quarterly basis when making decisions about the allocation of operating and capital resources.

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Net operating loss carryforwards	$ 31,332	$ 23,201
Tax credits	25,427	16,939
Deferred revenue	3,536	4,305
Depreciation and amortization	1,216	1,159
Amortization	432	479
Stock-based compensation	1,681	1,126
Leasehold liability	17,842	17,044
Capitalized R&D costs	48,315	31,515
Other	9,391	3,824
Total deferred tax assets	139,172	99,592
Deferred tax liabilities:
Right of use Asset	(17,582)	(17,346)
Valuation allowance	$ (121,590)	$ (82,246)

Loan and Security Agreements (Tables)

12 Months Ended

Dec. 31, 2024

Debt Disclosure [Abstract]

Schedule of Future Principal Payments

Future principal payments as of December 31, 2024 are as follows (in thousands):


2027	$	4,063
2028		16,250
2029		12,187
Total principal payments		32,500
Plus: Final payment fee		1,625
Less: unamortized debt discount and final fee		(2,053	)
Total debt		32,072

Nature of Business and Basis of Presentation

12 Months Ended

Dec. 31, 2024

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 (TCR)-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, issuance of term loan in December 2024 and with payments received under its license and collaboration agreements. Since its inception, the Company has incurred recurring losses, including net losses of $127.5 million and $89.2 million for the years ended December 31, 2024 and 2023, respectively. As of December 31, 2024, the Company had an accumulated deficit of $375.1 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, 2024 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.

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Revenue
Collaboration and license revenue	$ 2,816	$ 21,049
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]	Collaboration And License Revenue	Collaboration And License Revenue
Operating expenses:
Research and development	$ 107,350	$ 88,153
General and administrative	30,287	26,354
Total operating expenses	137,637	114,507
Loss from operations	(134,821)	(93,458)
Other (expense) income:
Interest and other income, net	12,065	7,999
Interest expense	(3,653)	(3,759)
Loss on extinguishment of debt	(1,090)
Total other income	7,322	4,240
Net loss	$ (127,499)	$ (89,218)
Net loss per share, basic	$ (1.14)	$ (1.36)
Net loss per share, diluted	$ (1.14)	$ (1.36)
Weighted average common shares outstanding- basic	111,990,417	65,599,858
Weighted average common shares outstanding-diluted	111,990,417	65,599,858
Comprehensive loss:
Net loss	$ (127,499)	$ (89,218)
Other comprehensive gain:
Unrealized gain on available-for-sale securities	51
Comprehensive loss	$ (127,448)	$ (89,218)

Fair Value Measurements - Schedule of Assets Carried at Fair Value on a Hierarchy Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Assets, Fair Value Disclosure [Abstract]
Total financial assets	$ 281,165	$ 187,467
Government Securities
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure		76,483
Marketable securities, fair value disclosure	111,421	58,685
Cash Equivalents - Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	169,744	52,299
Active Markets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Total financial assets	281,165	187,467
Active Markets (Level 1) \| Government Securities
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure		76,483
Marketable securities, fair value disclosure	111,421	58,685
Active Markets (Level 1) \| Cash Equivalents - Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	$ 169,744	$ 52,299

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property and equipment	$ 25,946	$ 22,339
Less: accumulated depreciation and amortization	(18,704)	(14,597)
Property and equipment, net	7,242	7,742
Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property and equipment	19,371	15,653
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment	3,258	3,159
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	1,721	1,519
Office and Computer Equipment
Property, Plant and Equipment [Line Items]
Property and equipment	1,496	1,460
Construction-in-Progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 100	$ 548

Stock Based Compensation - Summary of Other Information Related to Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Weighted-average fair value of options granted	$ 4.90	$ 2.17
Intrinsic value of options exercised	$ 1,954	$ 152

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) Segment	Dec. 31, 2023 USD ($)
Restricted cash	$ 5,031,000	$ 5,031,000
Uncertain tax positions	$ 0	$ 0
Number of reportable segment \| Segment	1
Letter of Credit
Restricted cash	$ 5,000,000

Summary of Significant Accounting Policies - Property and Equipment Stated at Cost and Depreciated Using Straight-line Method Over Estimated Useful Lives (Details)	Dec. 31, 2024
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

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, 2024	Dec. 31, 2023
Collaboration And License Agreements [Line Items]
Collaboration and license revenue				$ 2,816	$ 21,049
Incurred costs				137,637	114,507
Deferred revenue, current portion				11,698	10,137
Long-term deferred revenue				$ 1,246	$ 5,622
Maximum \| Novartis Agreement
Collaboration And License Agreements [Line Items]
Ownership Interest				10.00%	10.00%
Minimum \| Novartis Agreement
Collaboration And License Agreements [Line Items]
Ownership Interest		10.00%	10.00%
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				$ 2,800	$ 14,200
Deferred revenue				12,900
Long-term deferred revenue				$ 1,200
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
Reimbursement cost					$ 1,900
Novartis \| Research Funding
Collaboration And License Agreements [Line Items]
Upfront payment received			$ 10,000