0000950170-24-034730 | 10-K | XBRL Viewer

Stock-Based Compensation

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock-based compensation

2021 stock option and grant plan

In July 2021, the Company established its 2021 Stock Option and Grant Plan (the “2021 Plan”) which provides for the granting of stock options, restricted and unrestricted stock units and restricted and unrestricted stock awards to employees and consultants of the Company. In connection with the closing of its IPO, on November 14, 2023 the Company's board of directors adopted the 2023 Incentive Award Plan (the “2023 Plan”, collectively with the 2021 Plan, the “Plans”) which became effective immediately. As a result of the 2023 Plan, the Company may not grant any additional awards under the 2021 Plan. The 2021 Plan will continue to govern outstanding equity awards granted thereunder.

2023 Incentive Award Plan

The Company initially reserved 4,212,860 shares of common stock plus the 6,022 remaining shares of common stock available for issuance under the 2021 Plan for issuance under the 2023 Plan. The shares of common stock reserved for issuance as stock options, restricted stock units, stock appreciation rights and restricted stock awards will automatically increase on the first day of January, including January 1, 2024 for a period of up to ten years in an amount equal to 5% of the total number of shares of the Company’s capital stock outstanding on the immediately preceding December 31, or a lesser number of shares as determined by the Company’s board of directors. On December 31, 2023, there were 3,893,858 shares available for issuance under the 2023 Plan.

Options granted under the 2023 Plan may be either incentive stock options (“ISOs”) or nonqualified stock options (“NSOs”). ISOs may be granted only to Company employees (including officers and directors who are also employees). NSOs may be granted to Company employees and consultants. The exercise price of an ISO and NSO shall not be less than 100% of the fair market value of the shares on the date of grant. The exercise price of an ISO granted to an employee who at the time of grant is a 10% stockholder shall not be less than 110% of the fair market value of the shares on the date of grant with a term not exceeding 5 years. To date, options have a term of 10 years and generally vest over a four-year period.

Stock options

Stock option activity for year ended December 31, 2023 was as follows:


	Number of Options			Weighted-Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022		167,882		$	1.09		9.65	$	—
Granted		3,928,714			7.64
Exercised		(27,787	)		1.23
Cancelled and forfeited		(348,354	)		5.32
Outstanding at December 31, 2023		3,720,455		$	7.61		9.49	$	57,821
Vested and expected to vest, December 31, 2023		3,720,455		$	7.61		9.49	$	57,821
Exercisable at December 31, 2023		128,968		$	4.46		9.13	$	2,410

Aggregate intrinsic value in the above table is calculated as the difference between the exercise price of the options and the Company’s estimated fair value of its common stock as of December 31, 2023.

The estimated weighted-average grant-date fair value of options granted during the years ended December 31, 2023 and 2022 was $6.10 and $0.79 per share, respectively. The aggregate intrinsic value of options exercised during the year ended December 31, 2023 was $0.3 million. No options were exercised during the year ended December 31, 2022. As of December 31, 2023, there was $19.8 million of unrecognized stock-based compensation related to stock options, which is expected to be recognized over a weighted-average period of 3.3 years.

Restricted stock awards

The Company has issued restricted stock awards to certain employees, directors and consultants in exchange for cash consideration equal to the fair value of common stock on the grant date. The restricted stock awards are subject to the repurchase right upon termination of services at a repurchase price lower of (i) the fair market value on the date of repurchase or (ii) their original purchase price no later than nine months after such termination. Shares purchased by employees pursuant to restricted stock awards are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules. Proceeds received from issuance of restricted stock awards are recorded as a share repurchase liability within accrued expenses and other current liabilities on the balance sheet and reclassified to additional paid-in capital as such awards vest.

In April 2022, certain restricted stock awards were modified to remove their performance conditions which was accounted for as an improbable-to-probable modification. As the Company determined that the service condition for these awards was not substantive, the Company recorded $0.2 million of stock-based compensation expense equal to the fair value of the modified awards in April 2022.

The following table summarizes the Company’s restricted stock activity:


	Number of Awards			Weighted-Average Grant Date Fair Value
Unvested as of December 31, 2022		529,110		$	0.93
Issued		1,874			3.94
Repurchased		(14,652	)		0.63
Vested		(276,633	)		1.18
Unvested as of December 31, 2023		239,699		$	0.93

The purchase price of the restricted stock awards is the fair value of common stock as determined by the board of directors at the issuance date. The shares generally vest monthly over four years from the grant date.

The Company recorded $0.1 million and $0.2 million in share repurchase liability for restricted stock awards in accrued expenses and other current liabilities in the balance sheets as of December 31, 2023 and 2022, respectively.

As of December 31, 2023, unrecognized stock-based compensation expense related to outstanding unvested restricted stock awards was $0.1 million, which is expected to be recognized over a weighted-average period 2.3 years.

Stock-based compensation expense

Total stock-based compensation expense recorded in the statements of operations and comprehensive loss was as follows:


	Year ended December 31,
	2023		2022
	(in thousands)
General and administrative	$	1,965	$	217
Research and development		1,362		80
Total stock-based compensation expense	$	3,327	$	297

The determination of the fair value of share-based payment awards on the date of grant is affected by the stock price, as well as assumptions regarding a number of complex and subjective variables. These variables include expected stock price volatility over the term of the awards, the expected period of time that stock options are expected to be outstanding, risk-free interest rates, and expected dividends. Estimating the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, is affected by assumptions regarding a number of complex variables. These inputs include:

•

Fair Value of Common Stock – Prior to the IPO, the fair value of the common stock underlying the stock awards was determined by the Company’s board of directors. Given the absence of a public trading market, the board of directors considered numerous objective and subjective factors to determine the fair value of the Company’s common stock at each meeting at which awards were approved. These factors included, but were not limited to (i) contemporaneous third-party valuations of common stock; (ii) the rights, preferences, and privileges of convertible preferred stock relative to common stock; (iii) the Company’s financial condition and operating results; (iv) the conditions of the biotechnology industry and the economy in general, (v) the stock price performance and volatility of comparable public companies; and (vi) the lack of marketability of the Company’s common stock. Subsequent to the IPO, the fair value of the common stock underlying stock awards is based on the closing price of the Company’s common stock as reported on the date of grant on the Nasdaq Global Select Market.

•

Expected Term – The expected term assumption represents the weighted-average period that the Company's share-based awards are expected to be outstanding. The Company has opted to use the “simplified method” for estimating the expected term of the options, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. The expected term of restricted stock awards was determined using the vesting term of the award.

•

Expected Volatility – Because the Company does not have sufficient trading history for its common stock, for all stock options granted to date, the volatility data was estimated based on a study of publicly traded industry peer companies. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size, and financial leverage of potential comparable companies.

•

Expected Dividend –The Black-Scholes option pricing model calls for a single expected dividend yield as an input. The Company currently have no history or expectation of paying cash dividends on our common stock.

•

Risk-Free Interest Rate– The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award.

The estimated grant-date fair value of awards granted was calculated based on the following assumptions:


	Year ended December 31,
	2023		2022
Expected term (in years)	5.2 – 6.4		2.8 – 6.1
Expected volatility	84.6% – 97.7%		84.6% – 89.8%
Expected dividend		—		—
Risk-free interest rate	3.2% – 4.7%		3.0% – 4.7%

Employee Stock Purchase Plan

On November 14, 2023 the Company's board of directors adopted the 2023 Employee Stock Purchase Plan (the “ESPP”) which became effective immediately. The Company initially reserved 386,725 shares of common stock for purchase under the ESPP. The number of shares of common stock reserved for issuance under the ESPP will automatically increase on the first day of January, including January 1, 2024 for a period of up to ten years in an amount equal to 1% of the total number of shares of the Company’s common stock outstanding on the immediately preceding December 31, or a lesser number of shares determined by the Company’s board of directors; however, no more than 6,561,663 share of common stock may be issued under the ESPP.

Purchases are accomplished through the participation of discrete offering periods. For each offering period, ESPP participants will purchase shares of common stock at a price per share equal to 85% of the lesser of the fair market value of the Company’s common stock on (1) the first trading day of the applicable offering period or (2) the last trading day of the applicable offering period. There were no shares issued under the ESPP during the year ended December 31, 2023.

Income Taxes - Summary of Income Tax Effect of Temporary Differences of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Depreciation and amortization		$ 1,220
Capitalized research and development costs	$ 17,935	6,009
Net operating loss carryforwards	2,277	1,244
Accrued expenses and other current liabilities	48	97
Operating lease liabilities	6,133	441
Tax credit carryforwards	2,658	2,350
Capitalized startup costs	7,670
Stock-based compensation	301	3
Total deferred tax assets	37,022	11,364
Deferred tax liabilities
Right of use assets	(6,064)	(465)
Fixed assets	(601)
Total deferred tax liabilities	(6,665)	(465)
Total net deferred tax assets	30,357	10,899
Less: valuation allowance	$ (30,357)	(10,899)
Net deferred tax assets		$ 0

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity

Stock option activity for year ended December 31, 2023 was as follows:


	Number of Options			Weighted-Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022		167,882		$	1.09		9.65	$	—
Granted		3,928,714			7.64
Exercised		(27,787	)		1.23
Cancelled and forfeited		(348,354	)		5.32
Outstanding at December 31, 2023		3,720,455		$	7.61		9.49	$	57,821
Vested and expected to vest, December 31, 2023		3,720,455		$	7.61		9.49	$	57,821
Exercisable at December 31, 2023		128,968		$	4.46		9.13	$	2,410

Summary of Restricted Stock Activity

The following table summarizes the Company’s restricted stock activity:


	Number of Awards			Weighted-Average Grant Date Fair Value
Unvested as of December 31, 2022		529,110		$	0.93
Issued		1,874			3.94
Repurchased		(14,652	)		0.63
Vested		(276,633	)		1.18
Unvested as of December 31, 2023		239,699		$	0.93

Summary of Stock Based Compensation Expense

Total stock-based compensation expense recorded in the statements of operations and comprehensive loss was as follows:


	Year ended December 31,
	2023		2022
	(in thousands)
General and administrative	$	1,965	$	217
Research and development		1,362		80
Total stock-based compensation expense	$	3,327	$	297

Summary of Estimated Grant Date Fair Value of Awards

The estimated grant-date fair value of awards granted was calculated based on the following assumptions:


	Year ended December 31,
	2023		2022
Expected term (in years)	5.2 – 6.4		2.8 – 6.1
Expected volatility	84.6% – 97.7%		84.6% – 89.8%
Expected dividend		—		—
Risk-free interest rate	3.2% – 4.7%		3.0% – 4.7%

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 405,732	$ 1,872
Prepaid expenses and other current assets	3,745	2,055
Total current assets	409,477	3,927
Operating lease right-of-use assets	28,222	2,165
Restricted cash	567
Property and equipment, net	10,379	3,368
Other non-current assets	4,391	783
Total assets	453,036	10,243
Current liabilities:
Accounts payable	5,013	3,483
Accrued clinical and research and development expenses	7,242	1,646
Accrued expenses and other current liabilities	6,629	3,391
Operating lease liabilities, current	2,278	1,006
Convertible notes-related party		11,635
Convertible notes		9,619
Derivative liabilities		12,705
Financial commitment liabilities-related party		412
Financial commitment liabilities		240
Total current liabilities	21,162	44,137
Operating lease liabilities, non-current	26,263	1,092
Other non-current liabilities	225	250
Total liabilities	47,650	45,479
Commitments and contingencies (Note 13)
Stockholders' equity (deficit):
Convertible preferred stock, $0.001 par value; 11,000,000 shares authorized and 810,700 issued and outstanding at December 31, 2022 (aggregate liquidation preference of $11,000 at December 31, 2022)		1
Common stock, $0.001 par value; 500,000,000 and 29,000,000 shares authorized at December 31, 2023 and 2022, respectively; 41,205,551 and 1,091,800 shares issued and outstanding at December 31, 2023 and 2022, respectively	41	1
Additional paid-in capital	550,491	11,761
Accumulated deficit	(145,146)	(46,999)
Total stockholders' equity (deficit)	405,386	(35,236)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	$ 453,036	$ 10,243

Statement of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Commissions and offering costs	$ 5,579
Convertible Preferred Stock
Issuance of tranche asset and liability	7,317
Settlement of tranche asset and liability	16,100
Series A-1 Redeemable Convertible Preferred Stock
Stock Issuance Costs	$ 841

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components [Abstract]
Depreciation expense	$ 1,491	$ 404

License and Research and Development Agreements

12 Months Ended

Dec. 31, 2023

Research and Development [Abstract]

License and Research and Development Agreements

10.

License and research and development agreements

Stanford license agreement

In August 2022, the Company entered into a license agreement with the Board of Trustees of the Leland Stanford Junior University (“Stanford University”) relating to the Company’s platform technologies relating to CAR T-cell therapies (the “Stanford License”). Pursuant to the Stanford License, Stanford University granted the Company a worldwide, exclusive license under certain patent rights, and a worldwide non-exclusive license under certain technology, in each case, owned or controlled by Stanford University, to make, use and sell products, methods or services in the field of human therapeutic and diagnostic products. The licensed patent rights cover platform technology relating to the use of CD2/CD58 co-stimulatory signaling in cell therapy.

As consideration for the licenses granted under the Stanford License, the Company made an upfront payment of $50,000 and issued 67,605 shares of its common stock with a fair value of $0.1 million, of which 22,317 shares were issued to Stanford University, 27,100 shares were issued to two non-profit organizations that supported the

research, and 18,188 shares were issued to various Stanford University inventors. The Company determined that the purchase of the licenses under the Stanford License represented an asset acquisition as it did not meet the definition of a business. As the acquired licenses represented in-process research and development (“IPR&D”) assets with no alternative future use, the Company recorded the upfront consideration of $0.2 million as research and development expense in August 2022, upon entering into the Stanford License. The Company recorded research and development expense pursuant to the Stanford License in the amount of $20,000 and $0.2 million during the years ended December 31, 2023 and 2022, respectively.

In addition to annual license maintenance fees of up to $0.1 million per year, the Company may be required to pay up to $7.5 million for sales milestone payments, up to $4.0 million in development milestone payments for each product covered by licensed patent rights upon initiation of specific clinical trials or receipt of regulatory approvals, up to $50,000 in a milestone payment upon achievement of commercial milestone event, up to $0.5 million in a milestone payment upon achievement of certain additional milestone events, and double-digit percentage milestone payments on the first two licensed non-patent products and, subject to certain royalty reductions, as applicable, low single-digit percentage royalties on net sales of products that are covered by the licensed patent rights or licensed technology. Subject to the terms of the Stanford License, the Company also agreed to pay Stanford University a certain percentage of non-royalty sublicense-related revenue that the Company receives from third-party sublicenses.

Crystal Mackall and Robbie Majzner, who were the Company’s principal owners and directors when the Company entered into the Stanford License, are employees and faculty members leading CAR T-cell therapy research programs at Stanford University.

Oxford license and supply agreement

In June 2022, the Company entered into a License and Supply Agreement (the “Oxford Agreement”), with Oxford Biomedica (UK) Limited (“Oxford”) for the manufacture and supply of lentiviral vectors for clinical and potentially commercial purposes by the Company. Pursuant to the Oxford Agreement, Oxford granted to the Company a non-exclusive worldwide, sub-licensable, royalty-bearing license under certain intellectual property rights for the purposes of research, development and commercialization of products transduced with the vectors manufactured by Oxford or by the Company following a technology transfer by Oxford, which products are directed against certain initial targets, and upon payment of certain fees, additional targets as agreed by Oxford and the Company.

As consideration for the license granted under the Oxford Agreement, the Company paid an upfront license fee of $0.2 million. The Company determined that the purchase of the license under the Oxford Agreement represented an asset acquisition as it did not meet the definition of a business. As the acquired license represented IPR&D assets with no alternative future use, the Company recorded the upfront payment of $0.2 million as research and development expense in June 2022, upon entering into the Oxford Agreement. The Company recorded research and development expense related to the achievement of certain development milestones in the amount of $0.3 million and $0.2 million during the years ended December 31, 2023 and 2022, respectively.

The Company may be required to pay up to an aggregate of $0.3 million of development milestones, $1.0 million of regulatory milestones and $8.0 million of commercial milestones for each target if such milestones are achieved by licensed products directed to such target. Additionally, the Company is obligated to pay an earned royalty on net sales of products manufactured with the Oxford vector at a low single-digit percentage.

Unless terminated earlier, the Oxford Agreement will expire when no further payments are due to Oxford. The Company can terminate the agreement at will upon advance written notice and may be subject to certain manufacturing slot cancellation fees.

National Cancer Institute

In March 2022, the Company entered into an exclusive license agreement (the “2022 NCI License”) with the U.S. Department of Health and Human Services, as represented by The National Cancer Institute (“NCI”), pursuant to which the Company obtained a worldwide, royalty-bearing, exclusive license under certain patent rights to make, use, sell, offer for sale, and import certain autologous products covered by such licensed patents in the field of

CAR-T immunotherapies for the treatment of B-cell malignancies that express CD22, and a non-sublicensable exclusive license to make, use, and import, but not sell, certain allogenic products and to practice processes in the field of certain CAR-T immunotherapies for the treatment of B-cell malignancies that express CD22 for evaluation purposes, with an exclusive option to negotiate a non-exclusive or exclusive commercialization license. The exclusive option can be extended once for one year on payment of an extension royalty of $50,000.

As consideration for the licenses granted under the 2022 NCI License, the Company is required to pay the NCI a non-refundable license fee of $0.6 million, of which $0.2 million was paid in 2022, and $0.1 million was paid in 2023, and the remaining balance of $0.3 million is payable in two equal annual installments beginning on the second anniversary of the effective date of the agreement. The Company accrued the non-refundable upfront fees of $0.4 million upon entering into the 2022 NCI License. As of December 31, 2023 and 2022, $0.1 million and $0.1 million, respectively, of non-refundable upfront fees were accrued in accrued expenses and other current liabilities and $0.2 million and $0.3 million, respectively, are classified as other non-current liabilities on the balance sheet. The Company determined that the purchase of the license under the 2022 NCI License represented an asset acquisition as it did not meet the definition of a business. As the acquired license represented IPR&D assets with no alternative future use, the Company recorded the initial consideration of $0.6 million under the 2022 NCI License as research and development expense in March 2022, upon entering into the 2022 NCI License. During the year ended December 31, 2023, the Company recorded research and development expense of $0.6 million related to the minimum annual royalty and the achievement of certain development milestones.

The Company agreed to pay up to $0.2 million in regulatory milestone payments upon achieving specific regulatory filings, up to $1.8 million in development milestone payments upon achieving specific clinical trials or registration trials, and up to $16.0 million in sales milestones upon achievement of specific commercial milestone events for up to three distinct licensed products, and an earned royalty on net sales of autologous cell therapy products covered by the licensed patent rights and, if the Company chooses to exercise the exclusive option mentioned above, on net sales of allogenic products, at a low single-digit percentage, depending on the amount of annual net sales and subject to the terms of the 2022 NCI License. The Company is also required to make minimum annual royalty payments of $50,000 per year, which will be creditable against royalties due for sales in that year. In addition, the Company is obligated to pay the NCI a percentage of non-royalty revenue received by the Company from its right to sublicense. Additionally, in the event the Company is granted a priority review voucher (“PRV”), the Company would be obligated to pay the NCI a minimum of $5.0 million upon the sale, transfer or lease of the PRV or $0.5 million upon submission of the PRV for use by the U.S. Food and Drug Administration (“FDA”). The Company is also obligated to pay the NCI a royalty based on a percentage of the fair market value of the consideration the Company receives for any assignment of the 2022 NCI License to a non-affiliate (upon the NCI’s prior written consent) or on an allocated portion of the fair value of consideration received in connection with a change in control (including an IPO). On the closing of the Company's IPO in November 2023, the change in control milestone was met.

The NCI may terminate or modify the 2022 NCI License in the event of an uncured material breach, including, but not limited to, if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event. The Company may terminate the license, or any portion thereof, at its sole discretion at any time upon 60 days written notice to the NCI.

In February 2023, the Company entered into an exclusive license agreement (the “2023 NCI License”) with the NCI, pursuant to which the Company obtained a worldwide, royalty-bearing, exclusive license under certain patent rights owned by the NCI to make, use, sell and import products and to practice processes in the field of certain CAR-T immunotherapies for the treatment of B-cell malignancies, wherein the T cells are engineered to express CD22 in combination with binders, CARs or other receptors targeting CD19, CD20, and/or CD79b; and at least one of the following: manufacturing the product with the STASH platform technology and/or a technology to activate CD2 signaling in the CAR T cell.

As consideration for the licenses granted under the 2023 NCI License, the Company must pay the NCI a non-refundable license fee of $0.3 million in three installments whereby the first installment is payable within 60 days of the execution of the agreement and the remaining two payments due on the first and second anniversaries of the effective date of the agreement. Additionally, the Company must reimburse the NCI for $0.1 million in expenses incurred by the NCI prior to January 1, 2022 related to the preparation, filing, prosecution, and maintenance of all

patent applications and patents included in the license under the 2023 NCI License. The Company determined that the purchase of the license under the 2023 NCI License represented an asset acquisition as it did not meet the definition of a business. As the acquired license represented IPR&D assets with no alternative future use, upon entering the 2023 NCI License in February 2023, the Company recorded the initial consideration of $0.4 million under the 2023 NCI License, consisting of the non-refundable upfront fees, as research and development expense. The Company accrued these amounts of which $0.1 million is classified as other non-current liabilities on the balance sheet as of December 31, 2023. During the year ended December 31, 2023, the Company recorded research and development expense of $0.4 million related to the minimum annual royalty.

The Company agreed to pay up to $0.1 million in regulatory milestone payments upon making specific regulatory filings, up to $1.7 million in development milestone payments upon achieving specific clinical trials or registration trials, and up to $16.0 million in sales milestones upon achievement of specific commercial milestone events. Subject to the terms of the 2023 NCI License, the Company also agreed to pay a low single-digit percentage on earned royalties on net sales of products covered by the licensed patent rights. The Company also agreed to make minimum annual royalty payments of $50,000 per year, which will be creditable against royalties due for sales in that year. In addition, the Company is obligated to pay the NCI a percentage of non-royalty revenue received by the Company from its right to sublicense at defined percentages. Additionally, if the Company is granted a PRV, the Company would be obligated to pay the NCI a minimum of $5.0 million upon the sale, transfer or lease of the PRV or $0.5 million upon submission of the PRV for use by the FDA. The Company is also obligated to pay the NCI a royalty based on a percentage of the fair market value of the consideration the Company receives for any assignment of the 2023 NCI License to a non-affiliate (upon the NCI’s prior written consent) or on an allocated portion of the fair value of consideration received in connection with a change in control (including an IPO). On the closing of the Company's IPO in November 2023, the change in control milestone was met.

Unless earlier terminated, the 2023 NCI License will expire upon the expiration of the last to expire licensed patent right. The NCI may terminate or modify the 2023 NCI License in the event of an uncured material breach, including, but not limited to, if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event. The Company may terminate the license, or any portion thereof, at its sole discretion at any time upon 60 days written notice to the NCI.

In connection with the closing of the Company’s IPO in November 2023, the Company accrued a total of $0.3 million of research and development expense within accrued clinical and research and development expenses on the balance sheet related to the change in control royalty for both the 2022 NCI License and the 2023 NCI License.

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Current income tax expense	$ 0	$ 0
Deferred income tax expense	0	0
Net operating loss carryforwards	$ 2,277,000	1,244,000
Net operating loss carryforwards, limitations on use	The Federal net operating loss carryforwards do not expire and are limited to 80% of taxable income and California net operating loss carryforwards begin to expire in 2040.
Percentage of net operating loss carryforwards of taxable income	80.00%
Net increase in the valuation allowance	$ 19,500,000	9,600,000
Research and development credit carryforwards	$ 17,935,000	6,009,000
Percentage of ownership change of equity points	50.00%
Unrecognized tax benefits	$ 1,234,000	872,000	$ 35,000
Unrecognized tax benefits of accrued interest and penalties	0	$ 0
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	10,800,000
Research and development credit carryforwards	2,300,000
Unrecognized tax benefits	800,000
California
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	2,300,000
Research and development credit carryforwards	1,900,000
Unrecognized tax benefits	$ 400,000

Stock-Based Compensation - Summary of Estimated Grant Date Fair Value of Awards (Details) - Stock Options and Restricted Stock Awards	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected volatility, Minimum	84.60%	84.60%
Expected volatility, Maximum	97.70%	89.80%
Risk-free interest rate, Minimum	3.20%	3.00%
Risk-free interest rate, Maximum	4.70%	4.70%
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	5 years 2 months 12 days	2 years 9 months 18 days
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	6 years 4 months 24 days	6 years 1 month 6 days

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

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+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
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

Leases - Summary of Future Payments Associated with Company's Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Leases [Abstract]
2024	$ 2,988
2025	4,676
2026	7,224
2027	7,441
Thereafter	25,784
Total undiscounted lease payments	48,113
Less: imputed interest	(19,572)
Total operating lease liabilities	$ 28,541

Convertible Notes - Additional Information (Details)	1 Months Ended				3 Months Ended	7 Months Ended	12 Months Ended
Convertible Notes - Additional Information (Details)	Feb. 28, 2023 USD ($) $ / shares shares	Jan. 31, 2023 USD ($)	Oct. 31, 2022 USD ($) Tranche	Apr. 30, 2022 USD ($) Tranche	Dec. 31, 2022 USD ($)	Oct. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($)	Jan. 31, 2022 USD ($)
Convertible Notes [Line Items]
Derivative liabilities	$ 8,400,000				$ 12,705,000		$ 0	$ 12,705,000
Loss on extinguishment of convertible notes							$ (2,316,000)
Series A-2 Redeemable Convertible Preferred Stock
Convertible Notes [Line Items]
Preferred stock, convertible, conversion price \| $ / shares	$ 10.18
Issuance of redeemable convertible preferred stock upon conversion of convertible notes, shares \| shares	3,229,851						3,229,851
Outstanding principal and accrued interest	$ 32,900,000
Redeemable convertible preferred stock	35,600,000
Non-cash Interest Expense
Convertible Notes [Line Items]
Non-cash Interest expense							$ 1,600,000	4,900,000
October 2022 Convertible Notes
Convertible Notes [Line Items]
Number of tranches \| Tranche			3
Payments of debt issuance costs			$ 16,000
Maturity date			Oct. 28, 2023
Proceeds from convertible notes			$ 12,000,000
Fair value of financial commitment liabilities			1,200,000			$ 1,200,000
Carrying value of financial commitment liabilities							$ 700,000
2022 Convertible Notes
Convertible Notes [Line Items]
Convertible notes, interest rate							6.00%
Conversion price \| $ / shares							$ 20.36
Convertible preferred stock issued at lowest cash price per share							75.00%
Percentage outstanding convertible debt redeemable in cash							200.00%
Percentage outstanding interest on convertible debt redeemable in cash							100.00%
Percentage of common stock convertible debt other investors							10.00%
Derivative liabilities									$ 13,600,000
Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag							Derivative liabilities
Convertible notes	$ 24,900,000
2022 Convertible Notes \| Minimum
Convertible Notes [Line Items]
Qualified financing amount for conversion of convertible debt							$ 50,000,000
First Two Tranche \| October 2022 Convertible Notes
Convertible Notes [Line Items]
Proceeds from convertible notes					8,500,000
Third Tranche \| October 2022 Convertible Notes
Convertible Notes [Line Items]
Proceeds from convertible notes		$ 3,500,000
Investor [Member] \| Series A-2 Redeemable Convertible Preferred Stock
Convertible Notes [Line Items]
Issuance of redeemable convertible preferred stock upon conversion of convertible notes, shares \| shares	1,833,623
Related Party \| October 2022 Convertible Notes
Convertible Notes [Line Items]
Financial commitment liabilities			700,000			700,000
Related Party \| Three Tranches \| October 2022 Convertible Notes
Convertible Notes [Line Items]
Proceeds from convertible notes			$ 5,400,000
Related Party \| Third Tranche \| October 2022 Convertible Notes
Convertible Notes [Line Items]
Proceeds from convertible notes		$ 2,200,000
April 2022 Convertible Notes
Convertible Notes [Line Items]
Number of tranches \| Tranche				3
Payments of debt issuance costs				$ 100,000
Maturity date				Apr. 26, 2023
Fair value of financial commitment liabilities				$ 700,000
Carrying value of financial commitment liabilities					$ 1,200,000			$ 1,200,000
April 2022 Convertible Notes \| Fourth Tranche
Convertible Notes [Line Items]
Debt instrument, available for issuance				5,000,000
April 2022 Convertible Notes \| Investor [Member]
Convertible Notes [Line Items]
Proceeds from convertible notes				25,000,000
April 2022 Convertible Notes \| Investor [Member] \| Three Tranches
Convertible Notes [Line Items]
Proceeds from convertible notes						$ 20,000,000
April 2022 Convertible Notes \| Related Party
Convertible Notes [Line Items]
Financial commitment liabilities				400,000
April 2022 Convertible Notes \| Related Party \| Three Tranches
Convertible Notes [Line Items]
Proceeds from convertible notes				$ 10,600,000

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) Segment MaterialShortTermLease	Dec. 31, 2022 USD ($) MaterialShortTermLease	Nov. 14, 2023 USD ($)
Debt Instrument [Line Items]
Number of operating segment \| Segment	1
Number of reporting segment \| Segment	1
Impairments of long-lived assets	$ 0	$ 0
Interest or penalties charged in relation to unrecognized tax benefits	$ 0
Number of material short-term leases \| MaterialShortTermLease	0	0
IPO
Debt Instrument [Line Items]
Deferred offering costs			$ 5,600,000

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables summarize the Company’s financial assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy:


	December 31, 2023
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Money market funds	$	398,017	$	—	$	—	$	398,017
Total financial assets	$	398,017	$	—	$	—	$	398,017


	December 31, 2022
	Level 1		Level 2		Level 3		Total
	(in thousands)
Liabilities:
Derivative liabilities	$	—	$	—	$	12,705	$	12,705
Total financial liabilities	$	—	$	—	$	12,705	$	12,705

Summary of Significant Assumptions Used in Valuation of Derivative Liability

The following table summarizes the significant inputs used in the valuation of the derivative liabilities:


	On Issuance Date of January 18, 2023			February 9, 2023
Expected term to achievement underlying triggering event (in years)	0.1 – 0.2				—
Probability of achievement of triggering event	0.0% – 95.0%				100.0	%
Discount rate		75.0	%		75.0	%

Summary of Change in Estimated Fair Value of Derivative Liabilities

The following table provide a summary of the change in the estimated fair value of the Company’s derivative liabilities during the year ended December 31, 2023:


	Derivative Liabilities
	(in thousands)
Balance as of December 31, 2022	$	12,705
Additions(1)		2,133
Change in fair value		(6,453	)
Settlement		(8,385	)
Balance as of December 31, 2023	$	—

(1) The additions to derivative liabilities in the year ended December 31, 2023 relate to the embedded derivative bifurcated from the final tranche of the 2022 Convertible Notes that was issued in January 2023.

Summary of Significant Inputs Used in Valuation of Financial Commitment Liabilities

The following table summarizes the significant inputs used in the valuation of the financial commitment liabilities on issuance:


	April 2022 Convertible Notes	October 2022 Convertible Notes
Expected term to achievement of milestone (in years)	0.3 – 0.5	0.1 – 0.3
Probability of achievement of milestone	81.0% – 90.0%	90.3% – 95.0%
Discount rate	1.2% – 1.9%	3.9% – 4.4%

Summary of Series Seed Tranche Commitment

The Series Seed tranche commitment is considered a contingent forward and the standard forward pricing model was used to measure the fair value on issuance using Level 3 inputs as follows:


	Series Seed Tranche Commitment
Expected term to achievement of milestone (in years)		0.9
Probability of achievement of milestone		90.0	%
Discount rate		0.1	%

Summary of Assumptions used to Redeemable Convertible Preferred Stock Tranche Asset and Liability

The redeemable convertible preferred stock tranche obligations are considered a contingent forward and the standard forward pricing model was used for the option pricing model with the following key assumptions:


	Redeemable Convertible Preferred Stock Tranche Asset						Redeemable Convertible Preferred Stock Tranche Liability
	On Issuance Date February 9, 2023			On Settlement Date of July 7, 2023			On Issuance Date February 9, 2023			On Settlement Date of October 27, 2023
Expected term to achievement of milestone (in years)		0.4			—		0.8				—
Probability of achievement of milestone		90.0	%		100	%		63.0	%		99.0	%
Discount rate		4.9	%		—			4.9	%		5.6	%

Summary of Changes in Fair Value of Redeemable Convertible Preferred Stock Tranche

The following table summarizes the changes in the fair value of the redeemable convertible preferred stock tranche asset and liability:


	Redeemable Convertible Preferred Stock Tranche Asset			Redeemable Convertible Preferred Stock Tranche Liability
	(in thousands)
Balance as of December 31, 2022	$	—		$	—
Initial recognition		1,788			(9,105	)
Change in fair value		122			(8,905	)
Settlement		(1,910	)		18,010
Balance as of December 31, 2023	$	—		$	—

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

+ References + Details

Fair Value Measurement - Summary of Series Seed Tranche Commitment (Details) - Level 3	12 Months Ended
	Dec. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Series Seed tranche commitment, Expected term to achievement of milestone	10 months 24 days
Series Seed tranche commitment, Probability of achievement of milestone	90.00%
Series Seed tranche commitment, Discount rate	0.10%

Subsequent Events

12 Months Ended

Dec. 31, 2023

Subsequent Events [Abstract]

Subsequent Events

15.

Subsequent events

Oxford license and supply agreement

In March 2024, the Company entered into an amendment to the Oxford Agreement to amend the royalty payment structure for vectors manufactured by Oxford. The Company is not obligated to pay royalties on licensed products related to CRG-022 and is obligated to pay an additional target fee of $0.5 million and earned royalty on net sales of licensed products related to targets other than CRG-022. The Company is obligated to pay reduced regulatory and commercial milestone payments for CRG-022 and is obligated to pay up to $1.0 million in regulatory milestones for each target (except for CRG-022) if such milestones are achieved for the licensed product.

Organization

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization

Description of the business

CARGO Therapeutics, Inc. (the “Company”) was incorporated in the state of Delaware in December 2019 as Syncopation Life Sciences, Inc. and changed its name to CARGO Therapeutics, Inc. in September 2022. It is a clinical-stage biotechnology company positioned to advance next generation, potentially curative cell therapies for cancer patients. The Company’s programs, platform technologies, and manufacturing strategy are designed to directly address the key limitations of approved cell therapies, including limited durability of effect, suboptimal safety and unreliable supply. The Company’s lead program, CRG-022, an autologous CD22 chimeric antigen receptor (“CAR”) T-cell therapy, has demonstrated robust safety, activity and manufacturability in clinical trials and is currently being studied in a potentially pivotal Phase 2 clinical trial for the treatment of large B-cell lymphoma (“LBCL”). The Company is also leveraging its proprietary cell engineering platform technologies to develop a pipeline of programs that incorporate multi-functional genetic “cargo” designed to enhance CAR T-cell persistence, as well as help safeguard against tumor resistance and T-cell exhaustion.

Since its founding, the Company has devoted substantially all of its resources to organizing and staffing the Company, business planning, raising capital, establishing licensing arrangements, building its proprietary platform technologies, discovering its product candidates, establishing its intellectual property portfolio, conducting research, preclinical studies, and clinical trials, establishing arrangements with third parties for the manufacture of its product candidates and related raw materials, and providing general and administrative support for these operations.

Reverse Stock Split

On November 1, 2023, the Company’s board of directors approved an amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s common stock and redeemable convertible preferred stock on a 13.5685-for-1 basis (the “Reverse Stock Split”) which was effected on November 3, 2023. The par value and authorized number of shares of common stock and redeemable convertible preferred stock were not adjusted as a result of the Reverse Stock Split. All share data and per share data amounts for all periods presented in the audited financial statements and notes thereto have been retrospectively adjusted to reflect the effect of the Reverse Stock Split.

Initial Public Offering

On November 14, 2023, the Company closed its initial public offering (“IPO”), pursuant to which it issued and sold an aggregate of 18,750,000 shares of its common stock at a public offering price of $15.00 per share and on November 21, 2023, the Company issued and sold 2,512,181 additional shares of its common stock to the underwriters of the IPO pursuant to the partial exercise of their option to purchase additional shares, resulting in net proceeds of $291.0 million, after deducting underwriting discounts, commissions and other offering expenses. Upon the closing of the IPO, the Company’s 18,836,561 outstanding shares of redeemable convertible preferred stock then outstanding automatically converted into 18,836,561 shares of common stock (see Note 7). Following the closing of the IPO, no shares of redeemable convertible preferred stock were authorized or outstanding.

In connection with the closing of its IPO, on November 14, 2023, the Company’s certificate of incorporation was amended and restated to authorize 500,000,000 shares of common stock, par value $0.001 per share and 50,000,000 shares of preferred stock, par value of $0.001 per share.

Liquidity

Since inception, the Company has incurred significant operating losses and negative cash flows, and it expects that it will continue to incur losses and negative cash flows for the foreseeable future as it continues its research and development efforts, advances its product candidates through preclinical and clinical development, enhances its platforms and programs, expands its product pipeline, seeks regulatory approval, prepares for commercialization, hires

additional personnel, protects its intellectual property and grows its business. As of and for the year ended December 31, 2023, the Company had an accumulated deficit of $145.1 million, cash and cash equivalents of $405.7 million and negative cash flows from operations of $81.2 million. The Company believes its existing cash and cash equivalents will be sufficient to support operations for at least 12 months from the issuance of these financial statements.

Fair Value Measurement - Summary of Change in Estimated Fair Value of Derivative Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Balance, start	$ 12,705
Additions	2,133
Change in fair value	(6,453)	$ 1,216
Settlement	(8,385)
Balance, end	$ 0	$ 12,705

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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+ Details

Leases - Schedule of Supplemental Cash Flow and Noncash Information Related to Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 2,495	$ 1,312
Total right-of-use assets capitalized	$ 28,258

Balance Sheet Components - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid research and development	$ 825	$ 1,428
Other receivables	1,739	476
Prepaid other	1,181	151
Total prepaid expenses and other current assets	$ 3,745	$ 2,055

Leases - Summary of Weighted-average Remaining Lease Term and Discount Rate (Details)	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Weighted-average remaining lease term (in years)	6 years 8 months 12 days	1 year 10 months 24 days
Weighted-average discount rate	13.60%	9.60%

Net Loss Per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss Per Share

14.

Net Loss Per Share

A reconciliation of net loss attributable to common stockholders and the number of shares in the calculation of basic and diluted loss per share was as follows:


	Year ended December 31,
	2023			2022
	(in thousands, except share and per share amounts)
Numerator:
Net loss attributable to common stockholders	$	(98,147	)	$	(40,951	)
Denominator:
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted		5,938,782			392,268
Net loss per share attributable to common stockholders, basic and diluted	$	(16.53	)	$	(104.40	)

The following potentially dilutive shares were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been anti-dilutive (on an as-converted basis):


	December 31,
	2023		2022
Outstanding stock options		3,720,455		167,882
Restricted stock awards subject to repurchase		239,699		529,110
Convertible preferred stock, as converted		—		810,700
2022 Convertible Notes, as converted		—		2,870,397
Total		3,960,154		4,378,089

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - Restricted Stock Award - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	$ 3,327	$ 297
General and Administrative
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	1,965	217
Research and Development
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	$ 1,362	$ 80

- Definition

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

+ References

+ Details

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
OPERATING ACTIVITIES
Net loss	$ (98,147)	$ (40,951)
Adjustments to reconcile net loss to net cash used in operating activities:
Net change in fair value of redeemable convertible preferred stock tranche obligations	8,783
Stock-based compensation expense	3,327	297
Loss on extinguishment of convertible notes	2,316
Amortization of operating lease right-of-use assets	2,201	1,040
Noncash interest expense	1,604	4,942
Depreciation	1,491	404
Acquired in-process research and development	1,505	1,013
Change in fair value of derivative liabilities	(6,453)	1,216
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,590)	(1,912)
Other non-current assets	(3,608)	(267)
Accounts payable	757	2,819
Accrued clinical and research and development expenses	4,673	1,222
Accrued expenses and other current liabilities	3,792	2,175
Operating lease liabilities	(1,815)	(1,070)
Net cash used in operating activities	(81,164)	(29,072)
INVESTING ACTIVITIES
Purchase of property and equipment	(8,277)	(2,724)
Purchase of in-process research and development	(715)	(558)
Net cash used in investing activities	(8,992)	(3,282)
FINANCING ACTIVITIES
Proceeds from issuance of common stock on initial public offering, net of commissions	296,607
Proceeds from issuance of redeemable convertible preferred stock and tranche obligations, net of issuance costs	199,918
Proceeds from issuance of convertible notes, net of issuance costs - related party	2,212	15,948
Proceeds from issuance of convertible notes, net of issuance costs	1,286	12,505
Proceeds from issuance of convertible preferred stock and tranche commitment, net of issuance costs		5,500
Proceeds from issuance of restricted stock awards		232
Proceeds from exercise of stock options	34
Payment of deferred initial public offering costs	(5,474)
Net cash provided by financing activities	494,583	34,185
Net increase in cash, cash equivalents and restricted cash	404,427	1,831
Cash and cash equivalents at beginning of period	1,872	41
Cash, cash equivalents, and restricted cash at end of period	406,299	1,872
COMPONENTS OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH
Cash and cash equivalents	405,732	1,872
Restricted cash	567
Total cash, cash equivalents, and restricted cash	406,299	1,872
SUPPLEMENTAL NON-CASH INVESTING AND FINANCING ACTIVITIES
Reclassification of shares of Series Seed redeemable convertible preferred stock to mezzanine equity	9,830
Conversion of convertible notes to shares of Series A-2 redeemable convertible preferred stock	35,576
Reclassification of tranche obligation asset to Series A-1 redeemable convertible preferred stock	1,910
Reclassification of tranche obligation liability to Series A-1 redeemable convertible preferred stock	18,010
Conversion of redeemable convertible preferred stock into common stock on completion of initial public offering	254,107
Purchase of property and equipment in accounts payable and accrued expenses and other current liabilities	883	623
In-process research and development costs in accounts payable, accrued expenses and other current liabilities, and other non-current liabilities	1,273	383
Issuance of shares in exchange for in-process research and development		72
Deferred offering costs related to initial public offering included in accounts payable and accrued expenses and other current liabilities	$ 105
Deferred issuance costs for second tranche of Series A-1 redeemable convertible preferred stock in accounts payable and accrued expenses and other current liabilities		$ 74

Fair Value Measurement - Summary of Changes in Fair Value of Redeemable Convertible Preferred Stock Tranche (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Redeemable Convertible Preferred Stock Tranche Liability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Balance, Start	$ 0
Initial recognition	(9,105)
Change in fair value	8,905
Settlement	(18,010)
Balance, End	0
Redeemable Convertible Preferred Stock Tranche Asset
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Balance, Start	0
Initial recognition	1,788
Change in fair value	122
Settlement	(1,910)
Balance, End	$ 0

Common Stock - Additional Information (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Nov. 14, 2023	Feb. 28, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock voting rights	one
Common stock, shares authorized	500,000,000	500,000,000	320,000,000	29,000,000
Common Stock, par value	$ 0.001	$ 0.001		$ 0.001
IPO
Class of Stock [Line Items]
Common stock, shares authorized		500,000,000
Common Stock, par value		$ 0.001

- Definition

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

+ References

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-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

+ Details

Preferred Stock - Additional Information (Details) $ / shares in Units, $ in Thousands		1 Months Ended					12 Months Ended
	Nov. 14, 2023 $ / shares shares	Oct. 31, 2023 USD ($) shares	Jul. 31, 2023 USD ($) shares	Feb. 28, 2023 USD ($) $ / shares shares	Jan. 31, 2022 USD ($) $ / shares shares	Feb. 28, 2021 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares issued								810,700
Redeemable convertible preferred stock, carrying value \| $								$ 10,855
Shares converted (in shares)	18,836,561
Convertible preferred stock, shares authorized	50,000,000							11,000,000
Convertible preferred stock, shares outstanding								810,700
Convertible preferred stock, par value \| $ / shares	$ 0.001							$ 0.001
Redeemable convertible preferred stock, shares outstanding	0							810,700
Minimum
Class of Stock [Line Items]
Percentage of voting power disposed of redemption event							50.00%
Series Seed Stock Purchase Agreement \| Series Seed Tranche Commitment
Class of Stock [Line Items]
Proceeds from the issue and sale of redeemable convertible preferred stock \| $						$ 100
Series A Preferred Stock Purchase Agreement
Class of Stock [Line Items]
Shares converted (in shares)	18,836,561
Conversion ratio	1
Convertible preferred stock, shares authorized	50,000,000
Convertible preferred stock, shares outstanding							0
Convertible preferred stock, par value \| $ / shares	$ 0.001
Series A Preferred Stock Purchase Agreement \| Series A-1 Tranche 2
Class of Stock [Line Items]
Fair value of redeemable convertible preferred stock tranche asset \| $				$ 1,800
Series A Preferred Stock Purchase Agreement \| Series A-1 Tranche 3
Class of Stock [Line Items]
Fair value of redeemable convertible preferred stock tranche liability \| $				$ 9,100
Series Seed Preferred Stock \| Series Seed Stock Purchase Agreement
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock, shares					405,350
Redeemable convertible preferred stock, par value \| $ / shares					$ 13.57	$ 13.57
Redeemable convertible preferred stock, shares issued						405,350
Issuance of Series Seed convertible preferred stock, shares						405,350
Proceeds from the issue and sale of redeemable convertible preferred stock \| $					$ 5,500	$ 5,500
Stock issuance costs \| $						$ 100
Redeemable convertible preferred stock, carrying value \| $					$ 100
Series Seed Preferred Stock \| Series Seed Stock Purchase Agreement \| Maximum
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock, shares						810,700
Series A-1 Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock, shares							14,796,010
Stock issuance costs \| $							$ 841
Series A-1 Redeemable Convertible Preferred Stock \| Series A Preferred Stock Purchase Agreement
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock, shares				5,072,919
Proceeds from the issue and sale of redeemable convertible preferred stock \| $				$ 68,100
Series A-1 Redeemable Convertible Preferred Stock \| Series A Preferred Stock Purchase Agreement \| Series A-1 Tranche 2
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock, shares			3,381,941	3,381,941
Redeemable convertible preferred stock, par value \| $ / shares				$ 13.57
Proceeds from the issue and sale of redeemable convertible preferred stock \| $			$ 45,800
Fair value of redeemable convertible preferred stock tranche asset \| $			$ 1,900
Series A-1 Redeemable Convertible Preferred Stock \| Series A Preferred Stock Purchase Agreement \| Series A-1 Tranche 3
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock, shares		6,341,150
Proceeds from the issue and sale of redeemable convertible preferred stock \| $		$ 86,000
Issuance of redeemable convertible preferred stock, shares							6,341,150
Redeemable convertible preferred stock, par value \| $ / shares							$ 13.57
Fair value of redeemable convertible preferred stock tranche liability \| $		$ 18,000
Series A-2 Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock upon conversion of convertible notes, shares				3,229,851			3,229,851
Preferred stock, convertible, conversion price \| $ / shares				$ 10.18
Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Redeemable convertible preferred stock, carrying value \| $								$ 0
Redeemable convertible preferred stock, shares outstanding								0

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Summary of significant accounting policies

Basis of presentation

The Company has prepared the accompanying financial statements in accordance with U.S. generally accepted accounting principles (“GAAP”). The financial statements are presented in U.S. dollars.

Use of estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting period. The Company bases its estimates on historical experience and on various other assumptions believed to be reasonable. Actual results could differ from those estimates and such differences could be material to the financial position and results of operations.

Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual of research and development expenses, the fair value of derivative liabilities and the initial fair value of the financial commitment liabilities related to the convertible notes, valuation of the redeemable convertible preferred stock tranche asset and liability, valuation of deferred tax assets, the fair value of equity instruments, equity-based instruments, stock-based compensation, and the determination of the incremental borrowing rate used to measure right-of-use assets and lease liabilities for the Company’s operating leases.

Risks and uncertainties

The Company is subject to all of the risks inherent in an early-stage company advancing new biotechnologies. These risks include, but are not limited to, the need for substantial additional financing, limited management resources, dependence upon medical acceptance of the product in development, regulatory approvals, successful clinical trials, availability, and willingness of patients to participate in human trials, and competition in the biopharmaceutical industry. The Company’s operating results may be materially affected by the preceding factors.

Segments

Operating segments are defined as components of an entity for which separate financial information is available and regularly reviewed by the chief operating decision maker, its Chief Executive Officer, in deciding how to allocate resources to an individual segment and in assessing performance. The Company has determined that it operates as one operating and reporting segment.

Cash, cash equivalents, and restricted cash

The Company considers all highly liquid investments purchased with an original maturity of three months or less on the date of purchase to be cash equivalents. Cash equivalents primarily consist of money market funds that are stated at fair value.

The Company considers restricted cash as cash and cash equivalents that cannot be withdrawn or used for general operating activities. Restricted cash consists of a letter of credit with a financial institution related to one of the Company's leases.

Issuance costs related to equity

The Company allocates issuance costs between the individual freestanding instruments identified on a relative fair value basis. Issuance costs associated with the issuance of stock or equity contracts (i.e., redeemable convertible preferred stock) are recorded as a charge against the gross proceeds of the offering.

The Company capitalizes certain legal, accounting, and other third-party fees that are directly related to the Company’s equity offering until such offering is consummated. On November 14, 2023, upon completion of IPO the Company recognized offering costs of $5.6 million as a reduction from gross proceeds associated with the IPO through additional paid-in capital in the accompanying balance sheet.

Property and equipment, net

Property and equipment, net is stated at cost, subject to adjustments for impairment, less accumulated depreciation. Depreciation is calculated using the straight-line method over the useful lives of the assets as follows:


Laboratory equipment	3 to 5 years
Furniture and fixtures	3 to 5 years
Computer equipment	3 to 5 years
Leasehold improvements	Shorter of useful life or remaining lease term

Maintenance and repairs are charged to expense as incurred, and improvements are capitalized and depreciated over their useful life as indicated above. Upon retirement or sale of the assets, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gains or losses are recorded in the statement of operations and comprehensive loss.

Impairment of long-lived assets

The Company reviews long lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future net undiscounted cash flows the assets are expected to generate. If such assets are considered to be impaired, the impairment charge is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. There have been no such impairments of long-lived assets during the periods presented.

Asset Acquisitions

The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the assets, which includes transaction costs. Goodwill is not recognized in asset acquisitions. In an asset acquisition, the cost allocated to acquire in-process research and development, (“IPR&D”) with no alternative future use is charged to research and development expense at the acquisition date.

Financial commitment liabilities

The Company’s convertible note purchase agreements executed in April 2022 and October 2022 (“2022 Convertible Notes”) included financial commitments to issue additional convertible notes to the noteholders in tranches (see Note 6) that were determined to be freestanding instruments that should be classified as liabilities. The freestanding instruments met the scope exception from derivative accounting. The proceeds of the first tranche of each of the 2022 Convertible Notes were allocated to the convertible notes and financial commitment liabilities based on their relative fair value at the date of issuance and not subsequently remeasured. The proceeds allocated to the financial commitment liabilities create a discount on the respective convertible note that is amortized as interest expense in the statements of operations and comprehensive loss using the effective interest rate method over the term of the respective convertible note. Upon settlement of each tranche, the respective portion of the financial commitment liabilities is reclassified to the carrying amount of the respective convertible note.

Income taxes

The Company accounts for income taxes using the asset and liability method whereby deferred tax asset and liability accounts are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that are currently in effect. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Financial statement effects of uncertain tax positions are recognized when it is more likely than not, based on the technical merits of the position, that it will be sustained upon examination. Interest and penalties related to unrecognized tax benefits are included within the provision (benefit) for income tax. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.

Derivative liabilities

The 2022 Convertible Notes contain certain embedded redemption features that are not clearly and closely related to the debt host instruments (see Note 6). These features are bifurcated from the host instruments and recorded at fair value on the date of issuance as derivative liabilities in accordance with Accounting Standards Codification (“ASC”) 815-15, Derivatives and Hedging—Embedded Derivatives. The derivative liabilities are remeasured to fair value each reporting period until settlement or extinguishment, with changes in the fair value recorded as a change in fair value of derivative liabilities in the statements of operations and comprehensive loss. Derivative liabilities are classified in the balance sheets as current or non-current based on whether or not net-cash settlement of the derivative instrument could be required within 12 months of the balance sheet date.

Redeemable convertible preferred stock tranche obligations

The obligations to issue additional shares of the Company’s Series A-1 redeemable convertible preferred stock in two tranches at a fixed price at future dates were determined to be freestanding financial instruments within the scope of ASC 480, Distinguishing Liabilities from Equity (“ASC 480”). On issuance, the Company recorded the redeemable convertible preferred stock tranche asset and liability on the balance sheet at their respective fair values. These tranche obligations are subject to remeasurement at each balance sheet date, with the net change in fair value recognized as a gain or loss on remeasurement within net change in fair value of redeemable convertible preferred stock tranche obligations in the statements of operations and comprehensive loss until settlement.

Leases

The Company is a lessee in a non-cancellable operating lease for laboratory and office facilities. The Company determines if an arrangement is or contains a lease at inception, which is the date on which the terms of the contract are agreed to, and the agreement creates enforceable rights and obligations. A contract is or contains a lease when (i) explicitly or implicitly identified assets have been deployed in the contract and (ii) the customer obtains substantially all of the economic benefits from the use of that underlying asset and has the right to control how and for what purpose the asset is used during the term of the contract. The Company also considers whether its service arrangements include the right to control the use of an asset.

For arrangements that meet the definition of a lease, the Company determines the initial classification and measurement of its right-of-use (“ROU”) asset and lease liability at the lease commencement date and thereafter if modified. Operating lease ROU assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make the contractual lease payments over the lease term. The operating lease ROU asset is initially measured at cost, which comprises the initial amount of the operating lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred less any lease incentives received. The operating lease liability is initially measured at the present value of the unpaid lease payments at the lease commencement date. The operating lease liability is subsequently measured at amortized cost using the effective-interest method. The lease term includes any renewal options that the Company is reasonably assured to exercise. As the rate implicit on the Company’s leases is not readily determinable, the Company uses its secured incremental borrowing rate to determine the present value of lease payments. The incremental borrowing rate is the rate of interest that the Company would have to pay to borrow an amount equal to the lease payments on a collateralized basis over a similar term and in a similar economic environment. The Company has elected not to record leases with an original term of 12 months or less on its balance sheets and recognizes those lease

payments in operating expenses in the statements of operations and comprehensive loss. During the years ended December 31, 2023 and 2022, there were no material short-term leases.

In addition, the Company’s leases may require payment of additional costs, such as utilities, maintenance, and other operating costs, which are generally referred to as non-lease components and vary based on future outcomes. The Company has elected not to separate lease and non-lease components. Only the fixed costs for lease components and their associated non-lease components are accounted for as a single lease component and recognized as part of an operating ROU asset and lease liability. Any variable expenses are recognized in operating expenses as incurred. Rent expense for an operating lease liability is recognized on a straight-line basis over the lease term and is included in operating expenses in the statements of operations and comprehensive loss.

Research and development expenses and accruals

Research and development expenses consist of direct costs, including manufacturing and technical operations, preclinical and clinical fees paid to clinical research organizations, supplies, health authority filings, technology licenses and in-process research and development (IPR&D) assets as well as indirect costs consisting of employee-related costs and allocated facilities and other operating costs. Research and development costs are expensed as incurred. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized as prepaid expenses until the related goods are delivered or services are performed. Such payments are evaluated for current or long-term classification based on when such services are expected to be received.

The Company estimates manufacturing and technical operations, preclinical study and clinical trial and research and development expenses based on the services performed, pursuant to contracts with research institutions and third-party service providers that conduct and manage preclinical studies and clinical trials and research services on its behalf. The Company records the costs of research and development activities based on the estimated services provided but not yet invoiced and includes these costs in accrued expenses and other current liabilities in the balance sheets. These costs are a component of the Company’s research and development expenses.

The Company accrues these costs based on factors such as estimates of the work completed in accordance with agreements established with its third-party service providers. The Company makes judgments and estimates in determining the accrued expenses balance. As actual costs become known, the Company adjusts its accrued expenses. The Company has not experienced any material differences between accrued costs and actual costs incurred. However, the status and timing of actual services performed may vary from the Company’s estimates, resulting in adjustments to expenses in future periods. Changes in these estimates that result in material changes to the Company’s accrued expenses could materially affect the Company’s results of operations. Contingent milestone payments, if any, are expensed when the milestone results are probable and estimable, which is generally upon the achievement of the milestone.

Stock-based compensation

The Company provides share-based payments in the form of stock options and restricted stock awards. For awards only subject to service conditions, the Company uses the straight-line attribution method for recognizing compensation expense over the requisite service period, which is generally the vesting period of the award. Compensation expense is recognized on awards ultimately expected to vest. Forfeitures are recorded when they occur.

For awards with performance vesting conditions, the Company evaluates the probability of achieving the performance condition at each reporting date. No compensation expense is recognized for awards subject to performance conditions until it is probable that the performance condition will be met. If the performance condition is probable of being achieved, the Company recognizes expense for such performance awards over the requisite service period using the accelerated attribution method.

The Company estimates the fair value of stock option awards and restricted stock awards on the grant date using a Black-Scholes option pricing model. The Company estimates the expected option lives using the simplified method, volatility using stock prices of peer companies, risk-free rates using the implied yield currently available on U.S.

Treasury zero-coupon issues with a remaining term equal to the expected term, and dividend yield based on the Company’s history of paying no dividends and expectation of paying no cash dividends on its common stock.

Net loss per share attributable to common stockholders

The Company follows the two-class method when computing net loss per share as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed.

Basic net loss per share attributable to common stockholders is computed using the weighted-average number of shares of common stock outstanding during the period excluding unvested restricted stock subject to repurchase. Diluted net loss per share attributable to common stockholders is computed using the sum of the weighted-average number of shares of common stock outstanding during the period and the effect of dilutive securities.

The Company’s convertible preferred stock contractually entitles the holders of such shares to participate in dividends but does not contractually require the holders of such shares to participate in losses of the Company.

Accordingly, in periods in which the Company reports a net loss, such losses are not allocated to such participating securities. As the Company was in a net loss position for the years ended December 31, 2023 and 2022, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders because the effects of potentially dilutive securities are antidilutive.

Comprehensive loss

Comprehensive loss represents the change in the Company’s stockholders’ deficit from all sources other than investments by or distributions to stockholders. The Company has no items of other comprehensive loss; as such, net loss equals comprehensive loss.

Emerging growth company status

The Company is an emerging growth company (“EGC”), as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued after the enactment of the JOBS Act until those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an EGC or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Recently adopted accounting pronouncements

In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which replaces the existing incurred loss impairment model with an expected credit loss model and requires a financial asset measured at amortized cost to be presented at the net amount expected to be collected. The Company adopted ASU 2016-13 on January 1, 2023, using a modified retrospective approach. The adoption did not have a material impact on the Company’s financial statements.

Recently issued accounting pronouncements not yet adopted

In November 2023, the FASB issued ASU 2023-07, Segment Reporting—Improvements to Reportable Segment Disclosures. ASU 2023-07 requires disclosure of incremental segment information on an interim and annual basis and provides new segment disclosure requirements for entities with a single reportable segment. ASU 2023-07 is effective for all public companies for fiscal years beginning after December 15, 2023, and interim periods within fiscal periods beginning after December 15, 2024, and requires retrospective application to all prior periods presented in the financial statements. The Company is assessing the impact of the adoption of this standard on its financial statements.

In December 2023, the FASB issued ASU 2023-09, Income Taxes—Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires consistent categories and greater disaggregation of information in the rate reconciliation, income taxes paid disaggregated by jurisdiction and certain other amendments to improve the effectiveness of income tax disclosures. ASU 2023-09 is effective for the Company beginning on January 1, 2025, with early adoption permitted. The Company is assessing the impact of the adoption of this standard on its financial statements.

From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the accompanying financial statements and disclosures.

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Summary of Computation of Diluted Net Loss per Share Attributable to Common Stockholders

A reconciliation of net loss attributable to common stockholders and the number of shares in the calculation of basic and diluted loss per share was as follows:


	Year ended December 31,
	2023			2022
	(in thousands, except share and per share amounts)
Numerator:
Net loss attributable to common stockholders	$	(98,147	)	$	(40,951	)
Denominator:
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted		5,938,782			392,268
Net loss per share attributable to common stockholders, basic and diluted	$	(16.53	)	$	(104.40	)

Summary of Potentially Dilutive Shares


	December 31,
	2023		2022
Outstanding stock options		3,720,455		167,882
Restricted stock awards subject to repurchase		239,699		529,110
Convertible preferred stock, as converted		—		810,700
2022 Convertible Notes, as converted		—		2,870,397
Total		3,960,154		4,378,089

Common Stock (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Summary of Reserved Common Stock For Issuance

The Company’s reserved common stock on an as-converted basis for issuance was as follows:


	December 31,
	2023		2022
Convertible preferred stock		—		810,700
Common stock options issued and outstanding under the Plans		3,720,455		167,882
Remaining shares available for issuance under the Plan		3,893,858		22,928
Remaining shares available for issuance under the ESPP		386,725		—
Total reserved common stock		8,001,038		1,001,510

Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 12,291	$ 3,789
Less: accumulated depreciation	(1,912)	(421)
Property and equipment, net	10,379	3,368
Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	9,644	2,712
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment at cost	87	34
Computer Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	593	47
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment at cost	134	105
Construction in Progress
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 1,833	$ 891

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Summary of Reconciliation of Effective Tax Rate for Income Taxes

The reconciliation of the effective tax rate for income taxes from the federal statutory rate were as follows:


	Year ended December 31,
	2023			2022
U.S. federal taxes at statutory rate		21.0	%		21.0	%
State tax – net of federal		0.3			(1.8	)
Federal tax credits		0.2			7.8
Change in valuation allowance		(19.8	)		(23.4	)
Stock-based compensation		(0.4	)		(0.1	)
Non-deductible expenses		(1.3	)		(3.2	)
Other		-			(0.3	)
Total		—	%		—	%

Summary of Income Tax Effect of Temporary Differences of Deferred Tax Assets

The income tax effect of temporary differences that give rise to significant portions of the Company’s deferred tax assets at December 31, 2023 and 2022 is presented below:


	December 31,
	2023			2022
	(in thousands)
Deferred tax assets:
Depreciation and amortization	$	—		$	1,220
Capitalized research and development costs		17,935			6,009
Net operating loss carryforwards		2,277			1,244
Accrued expenses and other current liabilities		48			97
Operating lease liabilities		6,133			441
Tax credit carryforwards		2,658			2,350
Capitalized startup costs		7,670			—
Stock-based compensation		301			3
Total deferred tax assets		37,022			11,364
Deferred tax liabilities
Right of use assets		(6,064	)		(465	)
Fixed assets		(601	)		—
Total deferred tax liabilities		(6,665	)		(465	)
Total net deferred tax assets		30,357			10,899
Less: valuation allowance		(30,357	)		(10,899	)
Net deferred tax assets	$	—		$	—

Summary of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
	2023			2022
	(in thousands)
Balance at the beginning of the year	$	872		$	35
Increases based on tax positions related to current year		717			837
Increases based on tax positions related to prior years		62			-
Reductions based on tax positions related to prior years		(417	)		-
Balance at end of year	$	1,234		$	872

Common Stock

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Common Stock

Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors. The voting, dividend, liquidation, and other rights and powers of the common stock are subject to and qualified by the rights, powers and preferences of preferred stock.

In February 2023, the Company amended and restated its certificate of incorporation to increase the authorized shares of common stock to 320,000,000.

In November 2023, in connection with the closing of its IPO, the Company’s certificate of incorporation was amended and restated to authorize 500,000,000 shares of common stock, par value $0.001 per share and a new class of preferred stock (see Note 7). Additionally, all classes of redeemable convertible preferred stock were cancelled.

Common stock issued and outstanding on the balance sheets and statements of stockholders’ equity (deficit) includes shares related to restricted stock that are subject to repurchase and therefore are excluded from the reserved common stock in the table below.

The Company’s reserved common stock on an as-converted basis for issuance was as follows:


	December 31,
	2023		2022
Convertible preferred stock		—		810,700
Common stock options issued and outstanding under the Plans		3,720,455		167,882
Remaining shares available for issuance under the Plan		3,893,858		22,928
Remaining shares available for issuance under the ESPP		386,725		—
Total reserved common stock		8,001,038		1,001,510

- Definition

The entire disclosure for equity.

+ References

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

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 1
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+ Details

Stock-Based Compensation - Additional Information (Details) - USD ($)		1 Months Ended	12 Months Ended
	Nov. 14, 2023	Apr. 30, 2022	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance			8,001,038	1,001,510
Option granted			$ 7.64
Restricted stock award description			The restricted stock awards are subject to the repurchase right upon termination of services at a repurchase price lower of (i) the fair market value on the date of repurchase or (ii) their original purchase price no later than nine months after such termination. Shares purchased by employees pursuant to restricted stock awards are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules
Share repurchase liability			$ 100,000	$ 200,000
Restricted Stock Award
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense			$ 100,000
Unrecognized stock-based compensation expense, weighted average period of recognition			2 years 3 months 18 days
Number of awards, Granted			1,874
Number of awards, Vested			276,633
Stock-based compensation expense			$ 3,327,000	$ 297,000
Performance Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation expense		$ 200,000
2023 Incentive Award Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance			3,893,858
Percentage of outstanding stock maximum			5.00%
Stock option expiration period			10 years
Percentage of price of shares granted at fair value			100.00%
2023 Incentive Award Plan \| 10% Stockholder
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Percentage of price of shares granted at fair value			110.00%
2023 Incentive Award Plan \| 10% Stockholder \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option expiration period			5 years
2023 Incentive Award Plan \| Incentive Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option expiration period			10 years
Vesting period			4 years
2021 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance			4,212,860
2021 Plan \| Remaining Shares Available For Issuance Under The 2021 Plans
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance			6,022
Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Estimated weighted-average grant-date fair value of options granted			$ 6.1	$ 0.79
Aggregate intrinsic value option exercised			$ 300,000	$ 0
Weighted-average grant-date per share fair value of options			$ 6.1	$ 0.79
Unrecognized compensation expense			$ 19,800,000
Unrecognized stock-based compensation expense, weighted average period of recognition			3 years 3 months 18 days
2023 ESPP Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares authorized for issuance			0
Common stock, capital shares reserved for future issuance	386,725
Percentage of outstanding stock maximum	1.00%
Stock option expiration period	10 years
Percentage of price of shares granted at fair value	85.00%
Number of shares issued under plan	6,561,663

Statement of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Redeemable Convertible Preferred Stock	Convertible Preferred Stock Preferred Stock	Series A-1 Redeemable Convertible Preferred Stock	Series A-2 Redeemable Convertible Preferred Stock
Beginning balance, shares at Dec. 31, 2021		810,699				405,350
Beginning balance, amount at Dec. 31, 2021	$ (175)	$ 1	$ 5,871	$ (6,048)		$ 1
Beginning balance, shares at Dec. 31, 2021		810,699				405,350
Beginning balance, amount at Dec. 31, 2021	(175)	$ 1	5,871	(6,048)		$ 1
Issuance of Series Seed convertible preferred stock, shares						405,350
Issuance of Series Seed convertible preferred stock, amount	5,500		5,500
Issuance of restricted stock awards, shares		213,496
Issuance of restricted stock awards, amount	3		3
Vesting of restricted stock awards	18		18
Issuance of common shares for license, shares		67,605
Issuance of common shares for license, amount	72		72
Stock-based compensation expense	297		297
Net loss	$ (40,951)			(40,951)
Ending balance, shares at Dec. 31, 2022	810,700				0
Ending balance, amount at Dec. 31, 2022	$ 10,855				$ 0
Ending balance, shares at Dec. 31, 2022		1,091,800				810,700
Ending balance, amount at Dec. 31, 2022	(35,236)	$ 1	11,761	(46,999)		$ 1
Reclassification of Series Seed redeemable convertible preferred stock, shares					810,700
Reclassification of Series Seed redeemable convertible preferred stock, amount					$ 9,830
Reclassification of series seed redeemable convertible preferred stock, shares						(810,700)
Reclassification of series seed redeemable convertible preferred stock, amount	(9,830)		(9,829)			$ (1)
Issuance of redeemable convertible preferred stock, shares							14,796,010
Issuance of redeemable convertible preferred stock, amount							$ 208,701
Issuance of redeemable convertible preferred stock upon conversion of convertible notes, shares								3,229,851
Issuance of redeemable convertible preferred stock upon conversion of convertible notes, amount								$ 35,576
Issuance of common stock on initial public offering, net of commissions and offering costs	291,028	$ 21	291,007
Issuance of common stock on initial public offering, net of commissions and offering costs, Shares		21,262,181
Conversion of redeemable convertible preferred stock to common stock on initial public offering					$ (254,107)
Conversion of redeemable convertible preferred stock to common stock on initial public offering, shares					(18,836,561)
Conversion of redeemable convertible preferred stock to common stock on initial public offering	254,107	$ 19	254,088
Conversion of redeemable convertible preferred stock to common stock on initial public offering, Shares		18,836,561
Issuance of restricted stock awards, shares		1,874
Vesting of restricted stock awards	$ 103		103
Repurchase of restricted stock awards		(14,652)
Exercise of stock options, shares	27,787	27,787
Exercise of stock options, amount	$ 34		34
Stock-based compensation expense	3,327		3,327
Net loss	(98,147)			(98,147)
Ending balance, shares at Dec. 31, 2023		41,205,551
Ending balance, amount at Dec. 31, 2023	$ 405,386	$ 41	$ 550,491	$ (145,146)

Common Stock - Summary of Reserved Common Stock For Issuance (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Total reserved common stock	8,001,038	1,001,510
Convertible Preferred Stock
Class of Stock [Line Items]
Total reserved common stock		810,700
Common Stock Options Issued And Outstanding Under The Plans
Class of Stock [Line Items]
Total reserved common stock	3,720,455	167,882
Remaining shares available for issuance under the Plan
Class of Stock [Line Items]
Total reserved common stock	3,893,858	22,928
Remaining Shares Available for Issuance Under the ESPP
Class of Stock [Line Items]
Total reserved common stock	386,725

- Definition

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

+ References

+ Details

Fair Value Measurement - Summary of Significant Inputs Used in Valuation of Financial Commitment Liabilities (Details)	12 Months Ended
	Dec. 31, 2023
Minimum \| April 2022 Convertible Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term to achievement of milestone	3 months 18 days
Probability of achievement of milestone	81.00%
Discount rate	1.20%
Minimum \| October 2022 Convertible Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term to achievement of milestone	1 month 6 days
Probability of achievement of milestone	90.30%
Discount rate	3.90%
Maximum \| April 2022 Convertible Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term to achievement of milestone	6 months
Probability of achievement of milestone	90.00%
Discount rate	1.90%
Maximum \| October 2022 Convertible Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term to achievement of milestone	3 months 18 days
Probability of achievement of milestone	95.00%
Discount rate	4.40%

Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2023

Class of Stock Disclosures [Abstract]

Summary of Convertible Preferred Stock

As of December 31, 2022, convertible preferred stock consisted of the following:


	December 31, 2022
	Shares Authorized		Shares Issued and Outstanding		Original Issuance Price		Liquidation Preference		Carrying Value
	(in thousands, except share and per share amounts)
Series Seed		11,000,000		810,700	$	13.57	$	11,000	$	10,855
Total		11,000,000		810,700			$	11,000	$	10,855

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2023

Balance Sheet Components [Abstract]

Summary of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following:


	December 31,
	2023		2022
	(in thousands)
Prepaid research and development	$	825	$	1,428
Other receivables		1,739		476
Prepaid other		1,181		151
Total prepaid expenses and other current assets	$	3,745	$	2,055

Summary of Property and Equipment, Net

Property and equipment, net consisted of the following:


	December 31,
	2023			2022
	(in thousands)
Laboratory equipment	$	9,644		$	2,712
Furniture and fixtures		87			34
Computer equipment		593			47
Leasehold improvements		134			105
Construction in progress		1,833			891
Property and equipment at cost		12,291			3,789
Less: accumulated depreciation		(1,912	)		(421	)
Property and equipment, net	$	10,379		$	3,368

Summary of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:


	December 31,
	2023		2022
	(in thousands)
Accrued compensation and related expenses	$	5,391	$	2,385
Accrued purchases of property and equipment		112		623
Accrued deferred offering costs related to the initial public offering		95		—
Other		1,031		383
Total accrued expenses and other current liabilities	$	6,629	$	3,391

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (98,147)	$ (40,951)

- Definition

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

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-Subparagraph (SX 210.5-03(20))
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-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, Beginning balance	167,882
Granted	3,928,714
Exercised	(27,787)
Cancelled and forfeited	(348,354)
Outstanding, Ending balance	3,720,455	167,882
Vested and expected to vest, December 31, 2023	3,720,455
Exercisable at December 31, 2023	128,968
Weighted Average Exercise Price
Beginning balance	$ 1.09
Granted	7.64
Exercised	1.23
Cancelled and forfeited	5.32
Ending balance	7.61	$ 1.09
Vested and expected to vest, December 31, 2023	7.61
Exercisable at December 31, 2023	$ 4.46
Weighted Average Remaining Contractual Term (in years)
Outstanding	9 years 5 months 26 days	9 years 7 months 24 days
Vested and expected to vest, December 31, 2023	9 years 5 months 26 days
Exercisable at December 31, 2023	9 years 1 month 17 days
Aggregate Intrinsic Value
Ending balance	$ 57,821
Vested and expected to vest, December 31, 2023	57,821
Exercisable at December 31, 2023	$ 2,410

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Lessee Disclosure [Abstract]

Summary of Future Payments Associated with Company's Operating Lease Liabilities

The future payments associated with the Company’s operating lease liabilities as of December 31, 2023 are as follows:


	Amount
	(in thousands)
2024	$	2,988
2025		4,676
2026		7,224
2027		7,441
Thereafter		25,784
Total undiscounted lease payments		48,113
Less: imputed interest		(19,572	)
Total operating lease liabilities	$	28,541

Summary of Total Lease Costs and Other Information

A summary of total lease costs and other information for the periods relating to the Company’s operating leases was as follows:


	Year ended December 31,
	2023			2022
	(in thousands)
Operating lease cost	$	2,873		$	1,282
Variable lease cost		620			317
Sublease income		(290	)		(240	)
Total lease cost	$	3,203		$	1,359

Summary of Weighted-average Remaining Lease Term and Discount Rate


	December 31,
	2023			2022
Other information:
Weighted-average remaining lease term (in years)		6.7			1.9
Weighted-average discount rate		13.6	%		9.6	%

Schedule of Supplemental Cash Flow and Noncash Information Related to Operating Leases

Supplemental cash flow and noncash information related to the Company’s operating leases were as follows:


	Year ended December 31,
	2023		2022
	(in thousands)
Cash flows from operating activities:
Cash paid for amounts included in the measurement of lease liabilities	$	2,495	$	1,312
Right-of-use assets obtained in exchange for lease obligations:
Total right-of-use assets capitalized	$	28,258	$	—

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

12.

Income taxes

The loss before provision for income taxes for the years ended December 31, 2023 and 2022 is entirely domestic. The Company has no current or deferred income tax expense for federal or state purposes for the years ended December 31, 2023 and 2022.

The reconciliation of the effective tax rate for income taxes from the federal statutory rate were as follows:


	Year ended December 31,
	2023			2022
U.S. federal taxes at statutory rate		21.0	%		21.0	%
State tax – net of federal		0.3			(1.8	)
Federal tax credits		0.2			7.8
Change in valuation allowance		(19.8	)		(23.4	)
Stock-based compensation		(0.4	)		(0.1	)
Non-deductible expenses		(1.3	)		(3.2	)
Other		-			(0.3	)
Total		—	%		—	%

The income tax effect of temporary differences that give rise to significant portions of the Company’s deferred tax assets at December 31, 2023 and 2022 is presented below:


	December 31,
	2023			2022
	(in thousands)
Deferred tax assets:
Depreciation and amortization	$	—		$	1,220
Capitalized research and development costs		17,935			6,009
Net operating loss carryforwards		2,277			1,244
Accrued expenses and other current liabilities		48			97
Operating lease liabilities		6,133			441
Tax credit carryforwards		2,658			2,350
Capitalized startup costs		7,670			—
Stock-based compensation		301			3
Total deferred tax assets		37,022			11,364
Deferred tax liabilities
Right of use assets		(6,064	)		(465	)
Fixed assets		(601	)		—
Total deferred tax liabilities		(6,665	)		(465	)
Total net deferred tax assets		30,357			10,899
Less: valuation allowance		(30,357	)		(10,899	)
Net deferred tax assets	$	—		$	—

As of December 31, 2023, the Company has net operating loss carryforwards of approximately $10.8 million and $2.3 million available to reduce future taxable income, if any, for Federal and California income tax purposes, respectively. The Federal net operating loss carryforwards do not expire and are limited to 80% of taxable income and California net operating loss carryforwards begin to expire in 2040.

The Company has established a full valuation allowance against its deferred tax assets due to the uncertainty surrounding realization of such assets. The net increase in the valuation allowance for the years ended December 31, 2023 and 2022 was $19.5 million and $9.6 million, respectively. In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred income tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred income tax liabilities, projected future taxable income, and tax-planning strategies in making this assessment. Based on these factors, management has provided a full valuation allowance for its deferred tax assets.

As of December 31, 2023, the Company has Federal and California research and development credit carryforwards of $2.3 million and $1.9 million, respectively. The Federal research and development credit carryforwards will expire beginning in 2042 if not utilized. The California research and development credits have no expiration date.

Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the “IRC”), if a corporation undergoes an “ownership change” (generally defined as a greater than 50 percentage points change (by value) in the ownership of its equity over a rolling three-year period), the corporation’s ability to use its pre-change net operating loss carryforwards and certain other pre-change tax attributes to offset its post-change income and taxes may be limited. California has similar rules. The Company conducted a Section 382 study and determined that it has experienced ownership changes in October 2020, February 2021, and February 2023. The ownership changes did not result in a permanent limitation of the pre-change net operating loss and research and development credit carryforwards. In addition, future changes in the Company's stock ownership, some of which are outside of its control, could result in an additional ownership change under Section 382 of the IRC.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
	2023			2022
	(in thousands)
Balance at the beginning of the year	$	872		$	35
Increases based on tax positions related to current year		717			837
Increases based on tax positions related to prior years		62			-
Reductions based on tax positions related to prior years		(417	)		-
Balance at end of year	$	1,234		$	872

As of December 31, 2023, the Company had $1.2 million of unrecognized tax benefits which are comprised of federal of $0.8 million and California of $0.4 million. The Company’s unrecognized gross tax benefits would not reduce its annual effective tax rate if recognized because the Company has recorded a full valuation allowance on deferred tax assets. The Company does not foresee any material changes to its gross unrecognized tax benefit within the next 12 months. The Company recognizes interest and/or penalties related to income tax matters in income tax expense. The Company did not recognize any accrued interest and penalties related to gross unrecognized tax benefits related to the years ended December 31, 2023, and 2022. All years are open for examination by federal and state authorities. The Company currently has no federal or state tax examinations in progress.

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

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

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

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

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

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

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

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

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

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

+ Details

Related Parties

12 Months Ended

Dec. 31, 2023

Related Parties

11.

Related parties

The 2022 Convertible Notes (see Note 7) were issued in part to a related party, a significant investor, for an aggregate principal amount of $16.0 million. As of December 31, 2022, $16.4 million in principal and accrued interest was outstanding to the related party. In February 2023, $18.7 million in principal and accrued interest outstanding to the related party was settled through conversion into 1,833,623 shares of Series A-2 redeemable convertible preferred stock (see Note 6).

Apart from the transactions and balances detailed in Note 6, Note 7 and Note 10, the Company has no other significant or material related party transactions during the years ended December 31, 2023 and 2022.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

+ Details

Net Loss Per Share - Summary of Potentially Dilutive Shares (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potentially dilutive shares excluded from computation of diluted net loss per share	3,960,154	4,378,089
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potentially dilutive shares excluded from computation of diluted net loss per share	3,720,455	167,882
Restricted Stock Awards Subject to Repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potentially dilutive shares excluded from computation of diluted net loss per share	239,699	529,110
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potentially dilutive shares excluded from computation of diluted net loss per share		810,700
2022 Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potentially dilutive shares excluded from computation of diluted net loss per share		2,870,397

Income Taxes - Summary of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 872	$ 35
Increases based on tax positions related to current year	717	837
Increases based on tax positions related to prior years	62
Reductions based on tax positions related to prior years	(417)
Balance at end of year	$ 1,234	$ 872

Income Taxes - Summary of Reconciliation of Effective Tax Rate for Income Taxes (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
U.S. federal taxes at statutory rate	21.00%	21.00%
State tax - net of federal	0.30%	(1.80%)
Federal tax credits	0.20%	7.80%
Change in valuation allowance	(19.80%)	(23.40%)
Stock-based compensation	(0.40%)	(0.10%)
Non-deductible expenses	(1.30%)	(3.20%)
Other		(0.30%)
Total		0.00%

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2023	Mar. 13, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Amendment Flag	false
Document Transition Report	false
Entity Registrant Name	CARGO Therapeutics, Inc.
Document Period End Date	Dec. 31, 2023
Entity Central Index Key	0001966494
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity File Number	001-41859
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-4080422
Entity Address, Address Line One	1900 Alameda Las Pulgas
Entity Address, Address Line Two	Suite 350
Entity Address, City or Town	San Mateo
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94403
City Area Code	650
Local Phone Number	379-6143
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	CRGX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Ex Transition Period	false
Entity Shell Company	false
Documents Incorporated by Reference [Text Block]	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant’s definitive proxy statement relating to the 2024 Annual Meeting of Stockholders, which will be filed with the Securities and Exchange Commission within 120 days after the end of the Registrant’s fiscal year ended December 31, 2023, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		39,363,052
Auditor Name	Deloitte & Touche LLP
Auditor Location	San Francisco, California
Auditor Firm ID	34

Fair Value Measurement - Summary of Significant Assumptions Used in Valuation of Derivative Liability (Details)	Jan. 18, 2023	Feb. 09, 2023
Probability of Achievement of Triggering Event
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, measurement input		1
Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, measurement input	0.75	0.75
Minimum \| Expected Term to Achievement Underlying Triggering Event
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, measurement input, expected term	1 month 6 days
Minimum \| Probability of Achievement of Triggering Event
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, measurement input	0
Maximum \| Expected Term to Achievement Underlying Triggering Event
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, measurement input, expected term	2 months 12 days
Maximum \| Probability of Achievement of Triggering Event
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, measurement input	0.95

Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Convertible preferred stock, par value		$ 0.001
Convertible preferred stock, shares authorized		11,000,000
Convertible preferred stock, shares issued		810,700
Convertible preferred stock, shares outstanding		810,700
Convertible preferred stock, aggregate liquidation preference		$ 11,000
Common Stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	29,000,000
Common stock, shares issued	41,205,551	1,091,800
Common stock, shares outstanding	41,205,551	1,091,800

Fair Value Measurement - Summary of Assumptions used to Redeemable Convertible Preferred Stock Tranche Asset and Liability (Details)	Feb. 09, 2023	Oct. 27, 2023	Jul. 07, 2023
Redeemable Convertible Preferred Stock Tranche Liability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term to achievement of milestone	9 months 18 days
Probability of achievement of milestone	63.00%	99.00%
Discount rate	4.90%	5.60%
Redeemable Convertible Preferred Stock Tranche Asset
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term to achievement of milestone	4 months 24 days
Probability of achievement of milestone	90.00%		100.00%
Discount rate	4.90%

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating expenses:
Research and development	$ 75,791	$ 29,373
General and administrative	20,919	5,398
Total operating expenses	96,710	34,771
Loss from operations	(96,710)	(34,771)
Interest expense	(1,604)	(4,942)
Net change in fair value of redeemable convertible preferred stock tranche obligations	(8,783)
Change in fair value of derivative liabilities	6,453	(1,216)
Loss on extinguishment of convertible notes	(2,316)
Other income (expense), net	4,813	(22)
Net loss and comprehensive loss	$ (98,147)	$ (40,951)
Net loss per share attributable to common stockholders, basic	$ (16.53)	$ (104.4)
Net loss per share attributable to common stockholders, diluted	$ (16.53)	$ (104.4)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic	5,938,782	392,268
Weighted-average shares used in computing net loss per share attributable to common stockholders, diluted	5,938,782	392,268

Subsequent events - Additional Information (Details) - Oxford License and Supply Agreement - Subsequent Event [Member] - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2024	Mar. 13, 2024
Subsequent Event [Line Items]
Additional target fee		$ 0.5
Maximum
Subsequent Event [Line Items]
Milestone Payments	$ 1.0

Leases - Additional Information (Details) $ in Thousands	12 Months Ended
Leases - Additional Information (Details) $ in Thousands	Dec. 31, 2023 USD ($) ft² SubleaseAgreement
Lessee, Lease, Description [Line Items]
Leases, term of contract	7 years
Lessee, Operating Lease, Existence of Option to Extend [true false]	true
Lease renewal term	3 years
Number of sublease agreements \| SubleaseAgreement	2
Area subleased \| ft²	2,300
Payments due within 12 months \| $	$ 2,988
Total undiscounted lease payments \| $	$ 48,113
San Carlos, California
Lessee, Lease, Description [Line Items]
Lease space \| ft²	99,557
San Mateo, California
Lessee, Lease, Description [Line Items]
Lease space \| ft²	31,117
Lease expiration date	Nov. 30, 2024
Letter of Credit
Lessee, Lease, Description [Line Items]
Letter of credit \| $	$ 600

Net Loss Per Share - Summary of Computation of Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net Income (Loss)	$ (98,147)	$ (40,951)
Denominator:
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic	5,938,782	392,268
Weighted-average shares used in computing net loss per share attributable to common stockholders, diluted	5,938,782	392,268
Net loss per share attributable to common stockholders, basic	$ (16.53)	$ (104.4)
Net loss per share attributable to common stockholders, diluted	$ (16.53)	$ (104.4)

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482635/260-10-55-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
-Subparagraph (SX 210.7-04(23))
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Reference 16: http://www.xbrl.org/2003/role/exampleRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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+ 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-Name Accounting Standards Codification
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-Paragraph 1
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

- Definition

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

+ References

+ Details

Fair Value Measurement

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurement

Fair value measurement

The Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Company determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels:

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

Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Carrying amounts of certain of the Company’s financial instruments including, cash, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate fair value due to the short-term nature of these instruments.

On a recurring basis, the Company measures certain financial liabilities at fair value. There were no transfers between levels during the years ended December 31, 2023 and 2022. The following tables summarize the Company’s financial assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy:


	December 31, 2023
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Money market funds	$	398,017	$	—	$	—	$	398,017
Total financial assets	$	398,017	$	—	$	—	$	398,017


	December 31, 2022
	Level 1		Level 2		Level 3		Total
	(in thousands)
Liabilities:
Derivative liabilities	$	—	$	—	$	12,705	$	12,705
Total financial liabilities	$	—	$	—	$	12,705	$	12,705

Derivative liabilities

In April and October 2022, the Company executed convertible note purchase agreements with its existing investors (see Note 7). The 2022 Convertible Notes contained certain embedded features requiring bifurcation as a single compound derivative instrument for each tranche funded. The derivative liabilities were measured at fair value using Level 3 inputs. The fair value of the derivative liabilities was estimated using a “with-and-without” method. The “with-and-without” methodology involves valuing the whole instrument on an as-is basis and then valuing the instrument without the embedded derivative. The difference between the entire instrument with the embedded derivatives and the instrument without the embedded derivatives is the fair value of the derivative liabilities. The estimated probability and timing of underlying events triggering the exercisability of the put option and conversion features contained within the 2022 Convertible Notes, forecasted cash flows and the discount rate were significant unobservable inputs used to determine the estimated fair value of the entire instrument with the embedded derivative. Significant increases (decreases) in any of those inputs in isolation would result in a significantly lower (higher) fair value measurement. The derivative liabilities are remeasured at each reporting period and the changes are recognized as a change in fair value of derivative liabilities on the statement of operations and comprehensive loss. The derivative liabilities were settled in February 2023 upon conversion of the 2022 Convertible Notes into Series A-2 redeemable convertible preferred stock (see Note 6).

The following table summarizes the significant inputs used in the valuation of the derivative liabilities:


	On Issuance Date of January 18, 2023			February 9, 2023
Expected term to achievement underlying triggering event (in years)	0.1 – 0.2				—
Probability of achievement of triggering event	0.0% – 95.0%				100.0	%
Discount rate		75.0	%		75.0	%

The following table provide a summary of the change in the estimated fair value of the Company’s derivative liabilities during the year ended December 31, 2023:


	Derivative Liabilities
	(in thousands)
Balance as of December 31, 2022	$	12,705
Additions(1)		2,133
Change in fair value		(6,453	)
Settlement		(8,385	)
Balance as of December 31, 2023	$	—

Financial commitment liabilities

The 2022 Convertible Notes included financial commitments to issue additional convertible notes to the noteholders in tranches (see Note 6). The proceeds of the issuance of the first tranche of each of the convertible notes issued in April 2022 and October 2022 were allocated to the convertible notes and financial commitment liabilities based on their relative fair value of $0.7 million and $1.2 million, respectively, of which $0.4 million and $0.7 million were associated with a related party, respectively, at the date of issuance and not subsequently remeasured. The fair value of the financial commitment liabilities on issuance was measured using the “with-and-without” method based on Level 3 inputs. The estimated probability and timing of underlying events triggering the closing of the subsequent tranches, forecasted cash flows and the discount rate were significant unobservable inputs used to determine the estimated fair value of the entire instrument.

The following table summarizes the significant inputs used in the valuation of the financial commitment liabilities on issuance:


	April 2022 Convertible Notes	October 2022 Convertible Notes
Expected term to achievement of milestone (in years)	0.3 – 0.5	0.1 – 0.3
Probability of achievement of milestone	81.0% – 90.0%	90.3% – 95.0%
Discount rate	1.2% – 1.9%	3.9% – 4.4%

Series Seed tranche commitment

The Series Seed stock purchase agreement included an obligation to issue additional shares of Series Seed convertible preferred stock in a future closing (see Note 7). The Series Seed tranche commitment was recorded at relative fair value upon the issuance of shares in the first closing and was not subsequently remeasured. The Series Seed tranche commitment is considered a contingent forward and the standard forward pricing model was used to measure the fair value on issuance using Level 3 inputs as follows:


	Series Seed Tranche Commitment
Expected term to achievement of milestone (in years)		0.9
Probability of achievement of milestone		90.0	%
Discount rate		0.1	%

Redeemable convertible preferred stock tranche obligations

The fair value of the Company’s redeemable convertible preferred stock tranche asset and liability (see Note 7) was calculated using an option pricing model using Level 3 inputs not observable in the market. Significant increases (decreases) in any of those inputs in isolation would result in a significantly lower (higher) fair value measurement. On settlement, the fair value of the redeemable convertible preferred stock tranche liability was calculated based on two scenarios, stay-private and IPO with early and late exit dates, each of which were probability weighted. The stay private scenario, weighted at a 30% probability, estimated the fair value using an option pricing model. The IPO scenario, weighted at a 70% probability, estimated the value of the Company upon an IPO at $380.0 million with an early IPO exit in less than 0.1 years and a late IPO exit in 0.3 years.


	Redeemable Convertible Preferred Stock Tranche Asset						Redeemable Convertible Preferred Stock Tranche Liability
	On Issuance Date February 9, 2023			On Settlement Date of July 7, 2023			On Issuance Date February 9, 2023			On Settlement Date of October 27, 2023
Expected term to achievement of milestone (in years)		0.4			—		0.8				—
Probability of achievement of milestone		90.0	%		100	%		63.0	%		99.0	%
Discount rate		4.9	%		—			4.9	%		5.6	%

The following table summarizes the changes in the fair value of the redeemable convertible preferred stock tranche asset and liability:


	Redeemable Convertible Preferred Stock Tranche Asset			Redeemable Convertible Preferred Stock Tranche Liability
	(in thousands)
Balance as of December 31, 2022	$	—		$	—
Initial recognition		1,788			(9,105	)
Change in fair value		122			(8,905	)
Settlement		(1,910	)		18,010
Balance as of December 31, 2023	$	—		$	—

- Definition

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

+ References + Details

Leases - Summary of Total Lease Costs and Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease cost	$ 2,873	$ 1,282
Variable lease cost	620	317
Sublease income	(290)	(240)
Total lease cost	$ 3,203	$ 1,359

Related Parties - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 28, 2023	Dec. 31, 2023	Dec. 31, 2022
Series A-2 Redeemable Convertible Preferred Stock
Related Party Transaction [Line Items]
Issuance of redeemable convertible preferred stock upon conversion of convertible notes, shares	3,229,851	3,229,851
Investor \| Series A-2 Redeemable Convertible Preferred Stock
Related Party Transaction [Line Items]
Issuance of redeemable convertible preferred stock upon conversion of convertible notes, shares	1,833,623
Investor \| 2022 Convertible Notes
Related Party Transaction [Line Items]
Aggregate principal amount		$ 16.0
Related party transaction principal and accrued interest outstanding	$ 18.7		$ 16.4

Preferred Stock

12 Months Ended

Dec. 31, 2023

Class of Stock Disclosures [Abstract]

Preferred Stock

Convertible preferred stock

Series Seed stock purchase agreement

In February 2021, the Company entered into a Series Seed stock purchase agreement for issuance of up to 810,700 shares of the Company’s Series Seed convertible preferred stock at a purchase price of $13.57 per share (the “Original Issuance Price”) in two closings. Concurrent with the execution of the agreement, the Company completed its first closing. In the first closing, the Company issued 405,350 shares of its Series Seed convertible preferred stock for aggregate gross proceeds of $5.5 million, less issuance costs of $0.1 million.

On issuance, the Company determined that its obligation to issue 405,350 shares of Series Seed convertible preferred stock in a future closing was a freestanding instrument that met the requirements of equity classification in accordance with ASC 815-40, Derivatives and Hedging — Contracts in Entity’s Own Equity, as it was indexed to the Company’s shares and could only be settled in shares. The proceeds of the issuance of the Series Seed convertible preferred stock and issuance costs were allocated to the Series Seed convertible preferred stock and the Series Seed tranche commitment based on their relative fair value. The Company recognized $0.1 million of the proceeds of the Series Seed convertible preferred stock in equity for the relative fair value of the Series Seed tranche commitment on issuance, with the remaining proceeds allocated to the Series Seed convertible preferred stock. No subsequent remeasurement of the freestanding instrument was required (see Note 3).

In January 2022, the Company completed the second closing and received aggregate net proceeds of $5.5 million for the issuance of 405,350 shares of Series Seed convertible preferred stock at a purchase price of $13.57 per share. Upon the second closing, the $0.1 million related to the Series Seed tranche commitment was reclassified to the carrying value of the Series Seed convertible preferred stock.

Series A preferred stock purchase agreement

In February 2023, the Company’s existing and new investors executed the Series A Preferred Stock Purchase Agreement (the “Series A Agreement”) pursuant to which the Company was obligated to sell shares of its redeemable convertible preferred stock immediately at execution and through a second and third tranche. In February 2023, the Company received net proceeds of $68.1 million from the issue and sale of 5,072,919 shares of Series A-1 redeemable convertible preferred stock and issued 3,229,851 shares of Series A-2 redeemable convertible preferred stock upon conversion of the 2022 Convertible Notes (see Note 6).

Pursuant to the Series A Agreement, through the second tranche, the Company was obligated to sell 3,381,941 shares of its Series A-1 redeemable convertible preferred stock for $13.57 per share (“Series A-1 Tranche 2”) upon the satisfaction of certain developmental milestones by the end of the third quarter of 2023. Additionally, the Company was obligated to sell 6,341,150 shares of its Series A-1 redeemable convertible preferred stock for $13.57 per share (“Series A-1 Tranche 3”) upon the satisfaction of certain developmental milestones by the middle of the first quarter of 2024. In July 2023, the Company achieved the milestone under the Series A-1 Tranche 2 and issued and sold 3,381,941 shares of its Series A-1 redeemable convertible preferred stock for net proceeds of $45.8 million. In October 2023, the Company issued and sold 6,341,150 shares of its Series A-1 redeemable convertible preferred stock as a part of the Series A-1 Tranche 3 closing for proceeds of $86.0 million.

On issuance, the Company determined that its obligation to issue additional shares of its Series A-1 redeemable convertible preferred stock in future closings were freestanding instruments in accordance with ASC 480. The Series A-1 Tranche 2 obligation was determined to be an asset as the issuance price was deemed to be in excess of the estimated fair value of the stock on the expected milestone achievement date. Conversely, the Series A-1 Tranche 3 obligation was determined to be a liability as the estimated fair value of the stock on the expected milestone achievement date was deemed to be in excess of the issuance price. Accordingly, the Company recognized $1.8 million and $9.1 million for the fair value of the redeemable convertible preferred stock tranche asset and liability, respectively, on the balance sheet and the remaining proceeds were allocated to the first tranche of Series A-1 redeemable convertible preferred stock. Changes in fair value of redeemable convertible preferred stock tranche asset and liability in subsequent reporting periods are recognized as a component of change in fair value of preferred stock tranche obligations in the statement of operations and comprehensive loss. In connection with the closing of Series A-1 Tranche 2 in July 2023, the fair value of the redeemable convertible preferred stock tranche asset of $1.9 million was reclassified to carrying amount of Series A-1 redeemable convertible preferred stock. In connection with the closing of Series A-1 Tranche 3 in October 2023, the fair value of the redeemable convertible preferred stock tranche liability of $18.0 million was reclassified to carrying amount of Series A-1 redeemable convertible preferred stock.

On November 14, 2023, the Company closed its IPO, and 18,836,561 outstanding shares of redeemable convertible preferred stock then outstanding automatically converted into shares of common stock on a 1:1 basis. Following the closing of the IPO, no shares of redeemable convertible preferred stock were authorized or outstanding.

As of December 31, 2022, convertible preferred stock consisted of the following:


	December 31, 2022
	Shares Authorized		Shares Issued and Outstanding		Original Issuance Price		Liquidation Preference		Carrying Value
	(in thousands, except share and per share amounts)
Series Seed		11,000,000		810,700	$	13.57	$	11,000	$	10,855
Total		11,000,000		810,700			$	11,000	$	10,855

Classification

A liquidation or winding up of the Company, including a merger or consolidation in which the Company or a subsidiary of the Company is a constituent party and the Company issues its shares as a part of such merger of consolidation, or the sale of substantially all of the assets, sales or exclusive license of all or substantially all of the intellectual property of the Company, or any other transaction or series of transactions in which more than 50% of the voting power of the Company is disposed of would constitute a redemption event. As of December 31, 2022, these

redemption events were deemed to be within the control of the Company; therefore, in accordance with ASC 480, all shares of Series Seed convertible preferred stock were presented within permanent equity.

Upon closing of the first tranche of shares of Series A-1 redeemable preferred stock and conversion of the 2022 Convertible Notes to shares of Series A-2 redeemable preferred stock on February 9, 2023, the convertible preferred stockholders collectively had the ability to elect a majority of the directors on the Company’s board of directors such that a redemption event pursuant to the various rights of shares of the convertible preferred stock was no longer within the control of the Company. In accordance with ASC 480, all shares of Series Seed convertible preferred stock were reclassified from permanent equity to mezzanine equity at fair value, and, on issuance, all shares of Series A-1 and A-2 redeemable convertible preferred stock were classified as mezzanine equity.

Preferred stock

In connection with the closing of its IPO, the Company’s certificate of incorporation was amended and restated to authorize 50,000,000 shares of preferred stock, par value of $0.001 per share. As of December 31, 2023, no shares of preferred stock were outstanding.

Preferred Stock - Summary of Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 14, 2023	Dec. 31, 2022
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	0	11,000,000
Redeemable convertible preferred stock, shares issued		810,700
Redeemable convertible preferred stock, shares outstanding	0	810,700
Redeemable convertible preferred stock, liquidation preference		$ 11,000
Redeemable convertible preferred stock, carrying value		$ 10,855
Series Seed
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		11,000,000
Redeemable convertible preferred stock, shares issued		810,700
Redeemable convertible preferred stock, shares outstanding		810,700
Redeemable convertible preferred stock, original issuance price		$ 13.57
Redeemable convertible preferred stock, liquidation preference		$ 11,000
Redeemable convertible preferred stock, carrying value		$ 10,855

- Definition

Carrying amount, attributable to parent, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(a)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.E.Q2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479830/718-10-S99-1

Reference 3: 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)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 4: 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 5: 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)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

+ Details

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock Award	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unvested, Number of Awards, Beginning balance \| shares	529,110
Number of Awards, Issued \| shares	1,874
Number of Awards, Repurchased \| shares	(14,652)
Number of Awards, Vested \| shares	(276,633)
Unvested, Number of Awards, Ending balance \| shares	239,699
Unvested, Weighted Average Grant Date Fair Value, Beginning balance \| $ / shares	$ 0.93
Weighted Average Grant Date Fair Value, Issued \| $ / shares	3.94
Repurchased, Weighted Average Grant Date Fair Value \| $ / shares	0.63
Vested, Weighted Average Grant Date Fair Value \| $ / shares	1.18
Unvested, Weighted Average Grant Date Fair Value, Ending balance \| $ / shares	$ 0.93

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Useful Lives of Assets

Depreciation is calculated using the straight-line method over the useful lives of the assets as follows:


Laboratory equipment	3 to 5 years
Furniture and fixtures	3 to 5 years
Computer equipment	3 to 5 years
Leasehold improvements	Shorter of useful life or remaining lease term

Summary of Significant Accounting Policies - Schedule of Useful Lives of Assets (Details)	Dec. 31, 2023
Laboratory Equipment \| Minimum
Property, Plant and Equipment [Line Items]
Useful lives	3 years
Laboratory Equipment \| Maximum
Property, Plant and Equipment [Line Items]
Useful lives	5 years
Furniture and Fixtures \| Minimum
Property, Plant and Equipment [Line Items]
Useful lives	3 years
Furniture and Fixtures \| Maximum
Property, Plant and Equipment [Line Items]
Useful lives	5 years
Computer Equipment \| Minimum
Property, Plant and Equipment [Line Items]
Useful lives	3 years
Computer Equipment \| Maximum
Property, Plant and Equipment [Line Items]
Useful lives	5 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration]	us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember

Balance Sheet Components

12 Months Ended

Dec. 31, 2023

Balance Sheet Components [Abstract]

Balance Sheet Components

Balance sheet components

Prepaid expenses and other current assets

Prepaid expenses and other current assets consisted of the following:


	December 31,
	2023		2022
	(in thousands)
Prepaid research and development	$	825	$	1,428
Other receivables		1,739		476
Prepaid other		1,181		151
Total prepaid expenses and other current assets	$	3,745	$	2,055

Property and equipment, net

Property and equipment, net consisted of the following:


	December 31,
	2023			2022
	(in thousands)
Laboratory equipment	$	9,644		$	2,712
Furniture and fixtures		87			34
Computer equipment		593			47
Leasehold improvements		134			105
Construction in progress		1,833			891
Property and equipment at cost		12,291			3,789
Less: accumulated depreciation		(1,912	)		(421	)
Property and equipment, net	$	10,379		$	3,368

Depreciation expense for the years ended December 31, 2023 and 2022 was $1.5 million and $0.4 million, respectively.

Accrued expenses and other current liabilities

Accrued expenses and other current liabilities consisted of the following:


	December 31,
	2023		2022
	(in thousands)
Accrued compensation and related expenses	$	5,391	$	2,385
Accrued purchases of property and equipment		112		623
Accrued deferred offering costs related to the initial public offering		95		—
Other		1,031		383
Total accrued expenses and other current liabilities	$	6,629	$	3,391

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases

In December 2023, the Company entered into a 7-year lease for 99,557 square feet of lab and office space in San Carlos, California. The agreement provides for two options to renew for three years which the Company is not reasonably certain to exercise. The Company is required to maintain a letter of credit for $0.6 million which has been classified as non-current restricted cash on the balance sheet.

The Company also leases 31,117 square feet of lab and office space in San Mateo, California which expires in November 2024. The Company was a sublessor in two agreements for a combined 2,300 square feet of the Company’s leased premises which expired in May 2023 and October 2023.

The future payments associated with the Company’s operating lease liabilities as of December 31, 2023 are as follows:


	Amount
	(in thousands)
2024	$	2,988
2025		4,676
2026		7,224
2027		7,441
Thereafter		25,784
Total undiscounted lease payments		48,113
Less: imputed interest		(19,572	)
Total operating lease liabilities	$	28,541

A summary of total lease costs and other information for the periods relating to the Company’s operating leases was as follows:


	Year ended December 31,
	2023			2022
	(in thousands)
Operating lease cost	$	2,873		$	1,282
Variable lease cost		620			317
Sublease income		(290	)		(240	)
Total lease cost	$	3,203		$	1,359


	December 31,
	2023			2022
Other information:
Weighted-average remaining lease term (in years)		6.7			1.9
Weighted-average discount rate		13.6	%		9.6	%

Supplemental cash flow and noncash information related to the Company’s operating leases were as follows:


	Year ended December 31,
	2023		2022
	(in thousands)
Cash flows from operating activities:
Cash paid for amounts included in the measurement of lease liabilities	$	2,495	$	1,312
Right-of-use assets obtained in exchange for lease obligations:
Total right-of-use assets capitalized	$	28,258	$	—

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

13.

Commitments and Contingencies

Indemnification agreements

In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to vendors, lessors, business partners, members of its board of directors, officers, and other parties with concerning certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by the Company, negligence or willful misconduct of the Company, violations of law by the Company, or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require the Company, among other things, to indemnify them against certain liabilities that may arise because of their status or service as directors, officers, or employees.

No demands have been made upon the Company to provide indemnification under such agreements, and thus, there are no claims that the Company is aware of that could have a material effect on the Company’s balance sheets, statements of operations and comprehensive loss, or statements of cash flows.

Litigation

Liabilities for loss contingencies arising from claims, assessments, litigation, fines, penalties, and other sources are recorded when it is probable that a liability has been incurred and the amount can be reasonably estimated. There are no matters currently outstanding for which any liabilities have been accrued. The Company was not a defendant in any lawsuit for the years ended December 31, 2023 and 2022.

Balance Sheet Components - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued Expenses and Other Current Liabilities [Abstract]
Accrued compensation and related expenses	$ 5,391	$ 2,385
Accrued purchases of property and equipment	112	623
Accrued deferred offering costs related to the initial public offering	95
Other	1,031	383
Total accrued expenses and other current liabilities	$ 6,629	$ 3,391

License and Research and Development Agreements - Additional Information (Details) - USD ($)	1 Months Ended					12 Months Ended
	Nov. 30, 2023	Feb. 28, 2023	Aug. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense						$ 75,791,000	$ 29,373,000
Other non-current liabilities						225,000	250,000
Stanford License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront payment			$ 50,000
Issuance of common shares for license, shares			67,605
Issuance of common shares for license, fair value			$ 100,000
Research and development expense			200,000			20,000	200,000
Stanford License \| Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual license maintenance fees			100,000
Stanford License \| Maximum \| Development Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments			4,000,000
Stanford License \| Maximum \| Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments			$ 7,500,000
Oxford License and Supply Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront license fee				$ 200,000
Oxford License and Supply Agreement \| Development Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense						300,000	200,000
Oxford License and Supply Agreement \| Regulatory Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments				1,000,000
Oxford License and Supply Agreement \| Commercial Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments				8,000,000
Oxford License and Supply Agreement \| Research and Development
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront license fee				200,000
Oxford License and Supply Agreement \| Maximum \| Development Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments				$ 300,000
2022 NCI License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment of extension royalty					$ 50,000
Non-refundable license fee					600,000	100,000	200,000
Remaining balance of non refundable license fee						$ 300,000
Accrued non refundable license fee					400,000
Minimum payment on sale, transfer or lease of PRV					5,000,000
Termination and expiration clause						NCI may terminate or modify the 2022 NCI License in the event of an uncured material breach, including, but not limited to, if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event. The Company may terminate the license, or any portion thereof, at its sole discretion at any time upon 60 days written notice to the NCI.
2022 NCI License \| Accrued Expenses and Other Current Liabilities Member
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Accrued non-refundable upfront fees						$ 100,000	100,000
2022 NCI License \| Other Noncurrent Liabilities
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Accrued non-refundable upfront fees						200,000	$ 300,000
2022 NCI License \| Accrued Clinical and Research and Development Expenses
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense	$ 300,000
2022 NCI License \| Research and Development
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable license fee					600,000
2022 NCI License \| Minimum Annual Royalty
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense						$ 600,000
2022 NCI License \| Maximum \| Development Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments					1,800,000
2022 NCI License \| Maximum \| Regulatory Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments					200,000
2022 NCI License \| Maximum \| Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments					16,000,000
2022 NCI License \| Minimum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum annual royalty payments					50,000
Minimum payment on submission of PRV					$ 500,000
2023 NCI License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum payment on sale, transfer or lease of PRV		$ 5,000,000
Termination and expiration clause						Unless earlier terminated, the 2023 NCI License will expire upon the expiration of the last to expire licensed patent right. The NCI may terminate or modify the 2023 NCI License in the event of an uncured material breach, including, but not limited to, if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event. The Company may terminate the license, or any portion thereof, at its sole discretion at any time upon 60 days written notice to the NCI.
Non-refundable license fee		300,000
Payment of reimburse in expense incurred on patent		100,000
Other non-current liabilities						$ 100,000
2023 NCI License \| Accrued Clinical and Research and Development Expenses
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense	$ 300,000
2023 NCI License \| Research and Development
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable license fee		400,000
2023 NCI License \| Minimum Annual Royalty
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense						$ 400,000
2023 NCI License \| Maximum \| Development Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments		1,700,000
2023 NCI License \| Maximum \| Regulatory Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments		100,000
2023 NCI License \| Maximum \| Sales Milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments		16,000,000
2023 NCI License \| Minimum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Minimum annual royalty payments		50,000
Minimum payment on submission of PRV		$ 500,000
Stanford University \| Stanford License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuance of common shares for license, shares			22,317
Non-profit Organizations \| Stanford License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuance of common shares for license, shares			27,100
Stanford University Inventors \| Stanford License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuance of common shares for license, shares			18,188
Commercial Milestone Event \| Stanford License \| Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments			$ 50,000
Certain Additional Milestone Events \| Stanford License \| Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments			$ 500,000

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of presentation

The Company has prepared the accompanying financial statements in accordance with U.S. generally accepted accounting principles (“GAAP”). The financial statements are presented in U.S. dollars.

Use of estimates

Risks and uncertainties

Segments

Cash, cash equivalents, and restricted cash

Issuance costs related to equity

Property and equipment, net


Laboratory equipment	3 to 5 years
Furniture and fixtures	3 to 5 years
Computer equipment	3 to 5 years
Leasehold improvements	Shorter of useful life or remaining lease term

Impairment of long-lived assets

Asset Acquisitions

Financial commitment liabilities

Income taxes

Derivative liabilities

Redeemable convertible preferred stock tranche obligations

Leases

payments in operating expenses in the statements of operations and comprehensive loss. During the years ended December 31, 2023 and 2022, there were no material short-term leases.

Research and development expenses and accruals

Stock-based compensation

Net loss per share attributable to common stockholders

Comprehensive loss

Emerging growth company status

Recently adopted accounting pronouncements / Recently issued accounting pronouncements not yet adopted

Recently adopted accounting pronouncements

Recently issued accounting pronouncements not yet adopted

Fair Value Measurement - Additional Information (Details) - USD ($) $ in Millions	Oct. 27, 2023	Oct. 31, 2022	Apr. 30, 2022
October 2022 Convertible Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of financial commitment liabilities		$ 1.2
October 2022 Convertible Notes \| Related Party
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Financial commitment liabilities		$ 0.7
April 2022 Convertible Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of financial commitment liabilities			$ 0.7
April 2022 Convertible Notes \| Related Party
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Financial commitment liabilities			$ 0.4
Stay-Private Scenario
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability weighted percentage	30.00%
IPO Scenario
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability weighted percentage	70.00%
Estimated value of redeemable convertible preferred stock	$ 380.0
Duration of late IPO exit	3 months 18 days
IPO Scenario \| Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Duration of early IPO exit	1 month 6 days

Organization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Nov. 21, 2023	Nov. 14, 2023	Dec. 31, 2023	Dec. 31, 2022	Feb. 28, 2023
Organization [Line Items]
Stockholders' equity, reverse stock split			13.5685-for-1 basis
Aggregate shares issued at public offering		18,750,000
Public offering price of shares		$ 15
Net proceeds from issuance of initial public offering			$ 296,607
Shares converted (in shares)		18,836,561
Redeemable convertible preferred stock, shares outstanding		0		810,700
Temporary Equity, Shares Outstanding		0		810,700
Redeemable convertible preferred stock, shares authorized		0		11,000,000
Common stock, shares authorized		500,000,000	500,000,000	29,000,000	320,000,000
Common Stock, par value		$ 0.001	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized		50,000,000		11,000,000
Convertible preferred stock, par value		$ 0.001		$ 0.001
Accumulated deficit			$ (145,146)	$ (46,999)
Cash and cash equivalents			405,732	1,872
Cash flows from operations			$ (81,164)	$ (29,072)
IPO
Organization [Line Items]
Additional shares issued to underwriters of IPO	2,512,181
Net proceeds from issuance of initial public offering	$ 291,000
Shares converted (in shares)		18,836,561
Common stock, shares authorized		500,000,000
Common Stock, par value		$ 0.001

Fair Value Measurement - Financial Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Feb. 28, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	$ 0	$ 8,400	$ 12,705
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	398,017
Total financial assets	398,017
Derivative liabilities			12,705
Total financial liabilities			12,705
Fair Value, Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	398,017
Total financial assets	$ 398,017
Fair Value, Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities			12,705
Total financial liabilities			$ 12,705

- Definition

+ References

+ Details

Convertible Notes

12 Months Ended

Dec. 31, 2023

Convertible Notes [Abstract]

Convertible Notes

In April 2022, the Company executed a convertible note purchase agreement with its existing investors for total proceeds of up to $25.0 million (the “April 2022 Convertible Notes”). The investors committed to purchase the notes in three tranches upon achievement of certain milestones, which were funded in April, August and October 2022 for aggregate gross proceeds of $20.0 million, of which $10.6 million was from a related party (see Note 11). The Company incurred $0.1 million in issuance costs for the April 2022 Convertible Notes. All three tranches had a maturity date of April 26, 2023. The Company had the option to request a fourth tranche of up to $5.0 million at the discretion of the investors under certain specific criteria. In February 2023, the April 2022 Convertible Notes were settled in connection with the Series A redeemable convertible preferred stock financing (see Note 7) and the option to request the fourth tranche expired.

In October 2022, the Company executed a convertible note purchase agreement with the same terms and with the same investors in the April 2022 Convertible Notes for total proceeds of up to $12.0 million (the “October 2022 Convertible Notes”), of which $5.4 million was from a related party. The investors committed to purchase the notes in three tranches upon achievement of certain milestones, of which the first two tranches were issued in October and December 2022 for aggregate gross proceeds of $8.5 million. The Company incurred $16,000 in issuance costs for the funded October 2022 Convertible Notes. In January 2023, the third tranche was issued upon achieving the third milestone for gross proceeds of $3.5 million, including $2.2 million issued to a related party. All three tranches had a maturity date of October 28, 2023. In February 2023, the October 2022 Convertible Notes were settled in connection with the Series A redeemable convertible preferred stock financing (see Note 7).

The 2022 Convertible Notes bear simple interest at 6.0% per annum. The principal and accrued interest could only be repaid prior to maturity upon consent of a majority of the investors or immediately upon demand.

The 2022 Convertible Notes were subject to automatic conversion upon the next financing whereby the Company issues its preferred equity securities and raises aggregate gross proceeds of at least $50.0 million (a “Qualified Financing”). On automatic conversion, the outstanding principal and accrued interest automatically convert into the convertible preferred stock issued in the Qualified Financing at 75% of the lowest cash price per share. The 2022 Convertible Notes were also subject to settlement by way of voluntary conversion that is not a Qualified Financing (a “Non-Qualified Financing”) where a majority of the active investors (investors who have fulfilled their funding commitments) could elect to convert the outstanding principal and interest into convertible preferred stock issued at 75% of the lowest cash price per share. In the event of a “Strategic Transaction” such as upon a change in control whereby another entity acquires the Company or the Company disposes of substantially all its assets upon sale, lease, liquidation, dissolution or winding up, whether voluntary or involuntary, or an IPO, then each active investor could choose to convert the note into the Company’s common stock at a conversion price of $20.36 per share or redeem the note in cash for 200% of the outstanding balance and 100% of accrued and unpaid interest. For investors who had not fulfilled their funding commitments related to the second and third tranches where the respective milestone conditions have been met, upon a Qualified Financing, a Non-Qualified Financing or a Strategic Transaction, the outstanding principal and interest of the note would automatically convert into shares of common stock at 10% of the then current common stock price.

The Company determined that the financial commitments to issue future tranches were freestanding instruments that did not meet the definition of a derivative and should be classified as liabilities. Upon issuance of the first tranche of the April 2022 Convertible Notes and October 2022 Convertible Notes, the Company recognized $0.7 million and $1.2 million, respectively, for the relative fair value of the financial commitment liabilities, of which $0.4 million and $0.7 million, respectively, were associated with a related party (see Note 3). Upon settlement of the financial commitments, for the years ended December 31, 2023 and 2022, $0.7 million and $1.2 million in financial commitment liabilities, respectively, were reclassified to the carrying amount of the respective convertible notes.

Due to the conversion and redemption features embedded within the 2022 Convertible Notes, the Company bifurcated compound derivative liabilities related to all tranches issued through December 31, 2023 (see Note 3). The aggregate fair value at issuance of the derivative liabilities was $13.6 million and was subsequently remeasured each reporting period. The allocation of proceeds of the 2022 Convertible Notes to the financial commitment liabilities and embedded derivatives created a discount on the respective convertible note that was amortized using the effective interest rate method over the term of the respective note. For the years ended December 31, 2023 and 2022, the Company recognized $1.6 million and $4.9 million, respectively, of non-cash interest expense, including accrued interest, amortization of the debt discount and amortization of debt issuance costs, in the statement of operations and comprehensive loss.

In February 2023, concurrent with the Series A redeemable convertible preferred stock financing (see Note 7), the terms of the 2022 Convertible Notes were amended to specify that the notes would convert into Series A-2 redeemable convertible preferred stock. The other contractual terms including the settlement method and the conversion price of $10.18 per share remained unchanged. Pursuant to the share settled redemption features as per the original contractual terms of the 2022 Convertible Notes, the Company issued 3,229,851 shares thereby settling $32.9 million in outstanding principal and accrued interest. Upon settlement, the carrying values of the 2022 Convertible Notes of $24.9 million and the derivative liabilities of $8.4 million were derecognized and the Series A-2 redeemable convertible preferred stock was recorded at its fair value of $35.6 million. The Company recognized a loss on extinguishment of $2.3 million in the statement of operations and comprehensive loss for the year ended December 31, 2023.