Fractyl Health, Inc. Common Stock (GUTS) 10-Q 13 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 03, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Document Transition Report	false
Current Fiscal Year End Date	--12-31
Entity File Number	001-41942
Entity Registrant Name	Fractyl Health, Inc.
Entity Central Index Key	0001572616
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-3553477
Entity Address, Address Line One	3 Van de Graaff Drive
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Burlington
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01803
City Area Code	781
Local Phone Number	902-8800
Title of 12(b) Security	Common Stock, $0.00001 par value per share
Trading Symbol	GUTS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		47,896,908

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 121,441	$ 33,209
Accounts receivable	15	22
Inventory	73	73
Restricted cash, current	315	315
Prepaid expenses and other current assets	2,628	2,029
Total current assets	124,472	35,648
Restricted cash, long-term	4,255	4,255
Property and equipment, net	1,902	490
Right-of-use lease assets, operating	29,613	30,282
Other long-term assets	3,277	5,537
Total assets	163,519	76,212
Current liabilities:
Accounts payable	1,027	553
Accrued expenses and other current liabilities	8,653	7,331
Operating lease liabilities, current	3,592	2,731
Warrant liabilities, current		573
Total current liabilities	13,272	11,188
Notes payable, long-term	28,695	55,152
Operating lease liabilities, long-term	28,246	28,508
Warrant liabilities, long-term	8,798	19,096
Other long-term liabilities	330
Total liabilities	79,341	113,944
Commitments and contingencies
Stockholders' equity (deficit):
Preferred stock, $0.00001 par value; 10,000,000 shares authorized, no shares issued or outstanding at March 31, 2024; no shares authorized, issued or outstanding at December 31, 2023
Common stock, $0.00001 par value; 300,000,000 shares authorized, 47,896,908 shares issued and outstanding at March 31, 2024; 107,000,000 shares authorized, 2,105,815 shares issued and outstanding at December 31, 2023	0	0
Additional paid-in capital	434,116	21,554
Accumulated deficit	(349,938)	(346,616)
Total stockholders' equity (deficit)	84,178	(325,062)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	$ 163,519	76,212
Series A, B, C-1, C-2, D, E and F Convertible Preferred Stock
Current liabilities:
Convertible preferred stock (Series A, B, C-1, C-2, D, E and F), $0.00001 par value; no shares authorized and no shares issued or outstanding at March 31, 2024; 78,112,639 shares authorized and 77,994,156 shares issued and outstanding at December 31, 2023; aggregate liquidation preference of $0 and $379,081 at March 31, 2024 and December 31, 2023, respectively		$ 287,330

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Temporary Equity [Abstract]
Preferred stock, par value	$ 0.00001	$ 0.00001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	300,000,000	107,000,000
Common stock, shares issued	47,896,908	2,105,815
Common stock, shares outstanding	47,896,908	2,105,815
Series A, B, C-1, C-2, D, E and F Convertible Preferred Stock
Temporary Equity [Abstract]
Convertible preferred stock, par value	$ 0.00001	$ 0.00001
Convertible preferred stock, shares authorized	0	78,112,639
Convertible preferred stock, shares issued	0	77,994,156
Convertible preferred stock, shares outstanding	0	77,994,156
Convertible preferred stock, liquidation preference	$ 0	$ 379,081

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Revenue	$ 33	$ 5
Cost of goods sold	19	3
Gross Profit	14	2
Operating expenses:
Research and development	14,424	9,349
Selling, general and administrative	7,132	2,760
Total operating expenses	21,556	12,109
Loss from operations	(21,542)	(12,107)
Other income (expense), net:
Interest income, net	1,098	417
Change in fair value of notes payable	6,686	(246)
Change in fair value of warrant liabilities	10,446	(5)
Other (expense) income, net	(10)	9
Total other income (expense), net	18,220	175
Net loss and comprehensive loss	(3,322)	(11,932)
Accretion of dividends on convertible preferred stock	(1,737)	(4,236)
Net loss attributable to common stockholders	$ (5,059)	$ (16,168)
Net loss per share attributable to common stockholders, basic	$ (0.17)	$ (7.87)
Net loss per share attributable to common stockholders, diluted	$ (0.17)	$ (7.87)
Weighted-average number of common shares outstanding, basic	29,736,911	2,055,399
Weighted-average number of common shares outstanding, diluted	29,736,911	2,055,399

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series A, B, C-1, C-2, D, E and F Convertible Preferred Stock	2022 Convertible Notes	Common Stock	Common Stock 2022 Convertible Notes	Additional Paid-in Capital	Additional Paid-in Capital 2022 Convertible Notes	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2022		77,994,156
Beginning Balance at Dec. 31, 2022		$ 287,330
Beginning Balance (in shares) at Dec. 31, 2022				2,055,399
Beginning Balance at Dec. 31, 2022	$ (252,319)					$ 17,206		$ (269,525)
Share-based compensation expense	857					857
Net loss	(11,932)							(11,932)
Ending Balance (in shares) at Mar. 31, 2023		77,994,156
Ending Balance at Mar. 31, 2023		$ 287,330
Ending Balance (in shares) at Mar. 31, 2023				2,055,399
Ending Balance at Mar. 31, 2023	(263,394)					18,063		(281,457)
Beginning Balance (in shares) at Dec. 31, 2023		77,994,156
Beginning Balance at Dec. 31, 2023		$ 287,330
Beginning Balance (in shares) at Dec. 31, 2023				2,105,815
Beginning Balance at Dec. 31, 2023	(325,062)					21,554		(346,616)
Issuance of common stock in initial public offering, net of underwriting discounts, commissions and offering costs (in shares)				7,433,332
Issuance of common stock in initial public offering, net of underwriting discounts, commissions and offering costs	100,277					100,277
Conversion of convertible preferred stock into common stock upon initial public offering (in shares)		(77,994,156)
Conversion of convertible preferred stock into common stock upon initial public offering		$ (287,330)
Conversion of convertible preferred stock into common stock upon initial public offering (in shares)				36,343,909	1,841,321
Conversion of convertible preferred stock into common stock upon initial public offering	287,330		$ 19,150			287,330	$ 19,150
Reclassification of warrant liability to equity upon initial public offering	425					425
Exercise of common stock warrants (in shares)				38,544
Exercise of common stock options (in shares)				133,987
Exercise of common stock options	163					163
Share-based compensation expense	5,217					5,217
Net loss	(3,322)							(3,322)
Ending Balance (in shares) at Mar. 31, 2024		0
Ending Balance (in shares) at Mar. 31, 2024				47,896,908
Ending Balance at Mar. 31, 2024	$ 84,178					$ 434,116		$ (349,938)

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Statement of Stockholders' Equity [Abstract]
Issuance of common stock in initial public offering, net of underwriting discounts, commissions and offering costs	$ 11,223

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (3,322)	$ (11,932)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	53	80
Non-cash interest expense	2
Non-cash operating lease expense	669	227
Loss on disposal of fixed assets	1
Stock-based compensation expense	5,217	857
Change in fair value of warrant liabilities	(10,446)	5
Change in fair value of notes payable, non-cash	(7,307)	246
Changes in operating assets and liabilities:
Accounts receivable	7	(5)
Inventory		(73)
Prepaid expenses and other current assets	(599)	711
Accounts payable	494	(222)
Accrued expenses and other current liabilities	2,854	965
Operating lease liabilities	599	(222)
Other long-term assets and liabilities	67	(187)
Net cash used in operating activities	(11,711)	(9,550)
Cash flows from investing activities:
Purchases of property and equipment	(1,059)	(20)
Net cash used in investing activities	(1,059)	(20)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriting discounts and commissions	103,695
Proceeds from exercise of stock options	163
Payments related to offering costs	(2,854)
Principal payments on finance lease obligations	(2)	(2)
Net cash provided by (used in) financing activities	101,002	(2)
Net increase (decrease) in cash, cash equivalents and restricted cash	88,232	(9,572)
Cash, cash equivalents and restricted cash at beginning of period	37,779	53,524
Cash, cash equivalents and restricted cash at end of period	126,011	43,952
Supplemental disclosure of cash flow information:
Interest paid	621
Payment for operating leases within operating activities	482	$ 391
Non-cash investing and financing activities:
Conversion of convertible preferred stock into common stock upon initial public offering	287,330
Conversion of 2022 Convertible Notes into common stock upon initial public offering	19,150
Reclassification of warrant liability to equity upon initial public offering	425
Finance lease right-of-use asset obtained in exchange for lease liability	427
Reclassification of deferred offering costs to additional paid-in capital	3,418
Purchases of property and equipment included in accounts payable	$ 20

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (3,322)	$ (11,932)

Insider Trading Arrangements

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

Nature of the Business

Nature of the Business	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	1. Nature of the Business Fractyl Health, Inc. (the “Company”) was incorporated on August 30, 2010 under the name MedCatalyst, Inc. The Company subsequently changed its name to Fractyl Laboratories Inc. on January 10, 2012 and subsequently to Fractyl Health, Inc. on June 9, 2021. The Company is a metabolic therapeutics company focused on pioneering new approaches to the treatment of metabolic diseases, including type 2 diabetes (“T2D”) and obesity. The Company’s goal is to transform metabolic disease treatment from chronic symptomatic management to durable disease modifying therapies that target the organ level root causes of T2D and obesity. The Revita DMR System (“Revita"), the Company’s lead product candidate, is an outpatient procedural therapy designed to durably modify duodenal dysfunction, a major pathologic consequence of a high fat and high sugar diet, which can initiate T2D and obesity in humans. The Company is evaluating Revita in its pivotal Revitalize-1 study and is currently enrolling patients with inadequately controlled T2D despite being on up to three anti-diabetic agents ("ADAs") and daily insulin. The Company is also planning to evaluate Revita in a two-part, parallel cohort, randomized, open-label clinical study, which is referred to as the Remain-1 study, for weight maintenance in patients with obesity who have lost at least 15% total body weight on GLP-1RA therapy and wish to discontinue their GLP-1RA without weight regain. In addition, the Company is developing Rejuva, a novel, locally administered, adeno-associated virus delivered pancreatic gene therapy platform. Rejuva is designed to enable long term remission of T2D and obesity by durably altering metabolic hormone function in the pancreatic islet cells of patients. The Company believes Revita and Rejuva, if approved, have the potential to revolutionize treatment across the spectrum of T2D and obesity, align the clinical and economic interest of key stakeholders around the long term regression of metabolic disease, and, at their fullest potential, significantly reduce the burden of metabolic disease globally. Initial Public Offering ("IPO") On February 6, 2024, the Company completed its IPO, pursuant to which it issued and sold 7,333,333 shares of its common stock at a price to the public of $ 15.00 per share, resulting in gross proceeds of approximately $ 110,000 and net proceeds of approximately $ 98,882 , after deducting the underwriting discount of approximately $ 7,700 and offering expenses of approximately $ 3,418 . On March 5, 2024, the Company issued an additional 99,999 shares of its common stock pursuant to the partial exercise of the underwriters’ option to purchase additional shares at the IPO public price of $ 15.00 per share, for additional gross proceeds of approximately $ 1,500 and net proceeds of approximately $ 1,395 , after deducting the underwriting discounts and commissions of approximately $ 105 . Liquidity Under ASC 205-40, Going Concern , management must evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved by the Company’s Board of Directors (“Board”) before the date that the financial statements are issued. The future success of the Company is dependent on its ability to develop its product candidates and ultimately upon its ability to attain profitable operations. The Company is subject to a number of risks similar to other early-stage life science companies, including, but not limited to, successful discovery and development of its product candidates, raising additional capital with favorable terms, development by its competitors of new technological innovations, protection of proprietary technology and market acceptance of the Company’s products. The successful discovery and development of product candidates requires substantial working capital which may not be available to the Company on favorable terms or not at all. The Company has a history of operating losses and had an accumulated deficit of $ 349,938 as of March 31, 2024. The Company has financed its operations to date primarily through sales of its convertible preferred stock, sales of its common stock in the IPO and debt financing. While a pilot commercial launch was initiated in Germany in the first quarter of 2023, the Company does not anticipate generating revenue from product sales in the United States unless and until it successfully completes clinical development and obtains marketing approvals from one or more of the product candidates. As a result, management expects continuing operating losses in the future. The Company believes that its cash and cash equivalents of $ 121,441 as of March 31, 2024 will be sufficient to fund the Company’s operating plan through 2025.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared by the Company in accordance with accounting principles generally accepted in the United States, or GAAP, for interim financial reporting and as required by Regulation S-X, Rule 10-01. The unaudited interim condensed consolidated financial statements have been prepared in accordance with GAAP and include the accounts of the Company and its wholly owned subsidiary. All intercompany balances and transactions have been eliminated. These interim financial statements, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair presentation of the Company’s financial position and results of operations for the three months ended March 31, 2024 and 2023. The results of operations for the interim periods are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2023 and notes thereto, included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on April 1, 2024. The accompanying unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements. 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 condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates relied upon in preparing these condensed consolidated financial statements include, but are not limited to, the fair value of common stock, the fair value of preferred and common stock warrants, the fair value of convertible notes payable, the fair value of stock-based awards, the incremental borrowing rate for lease accounting and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ materially from those estimates. Deferred Public Offering Costs Deferred public offering costs, which primarily consist of direct, incremental legal and accounting fees relating to the planned IPO, are capitalized within other long-term assets. The deferred public offering costs are offset against IPO proceeds upon the consummation of the offering. As of December 31, 2023, the Company had deferred offering-related costs of $ 2,180 . Upon closing of the Company’s IPO in February 2024, total deferred offering costs of $ 3,418 were transferred to additional paid-in capital to offset the IPO proceeds. The Company had no deferred offering costs as of March 31, 2024 . Leases The Company has entered into operating leases for office and laboratory spaces and finance leases for certain laboratory equipment, which are accounted for in accordance with ASC 842, Leases . The Company determines whether an arrangement is or contains a lease based on the unique facts and circumstances present in the arrangement at inception. Operating leases are included in right-of-use lease assets (“ROU assets”) and current and long-term lease liabilities on the Company’s condensed consolidated balance sheets. Lease expenses for operating leases are recognized on a straight-line basis over the lease term as an operating expense. Assets subject to finance leases are included in property and equipment, net, on the Company’s condensed consolidated balance sheets. Current and long-term portion of the related lease liabilities of the finance leases are included in accrued expenses and other current liabilities and other long-term liabilities, respectively, on the Company’s condensed consolidated balance sheets. Lease expenses for finance leases consist of depreciation of the assets, which is recognized on a straight-line basis over the useful life of the assets as an operating expense, and interest expense using the effective interest method over the lease term. At the lease commencement date, the Company recognizes an ROU asset and a lease liability based on the present value of fixed lease payments over the expected lease term. The Company typically only includes an initial lease term in its assessment of a lease arrangement. Options to renew a lease are not included in the Company’s assessment unless there is a reasonable certainty that the Company will renew. Certain adjustments to the ROU asset may be required for items such as incentives received. The interest rate implicit in the lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments, which reflects the fixed rate at which the Company could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. The Company has elected the short-term lease recognition exemption for short-term leases, which allows the Company not to recognize lease liabilities and ROU assets on the condensed consolidated balance sheets for leases with an original lease term of twelve months or less. Rent expenses for short-term leases are directly expensed as operating expenses in the condensed consolidated statements of operations and comprehensive loss. The Company has elected to not 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 the ROU asset and lease liability. Variable lease costs such as taxes, operating expenses and other expenses are based on actual costs incurred and are directly expensed as operating expenses in the condensed consolidated statements of operations and comprehensive loss. Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including lease modification. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. Stock-Based Compensation The Company measures all stock options and other stock-based awards based on their fair value on the date of the grant. Those awards typically have a graded vesting schedule and compensation expense for awards with only service conditions is recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the respective award. Compensation costs recognized for performance-based awards reflect the number of awards that are expected to vest during the requisite service period and are recognized using an accelerated attribution method. Upon final determination of the performance conditions achieved, the compensation costs are adjusted to reflect those awards that ultimately vest. Historical performance patterns, to the extent that they are indicative to the performance conditions to be achieved, are used in developing estimates for the probability of attaining these performance conditions. The Company classifies stock-based compensation expense in its condensed consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. Prior to the completion of the Company’s IPO, the Company determined the fair value of the underlying common stock by taking into consideration the results obtained from third-party valuations and additional factors that are deemed relevant, which incorporates significant judgments and estimates. After the completion of the Company’s IPO, the Company considers the fair value of its common stock to equal to the closing price of its common stock traded on the Nasdaq Global Market. The Company uses the Black-Scholes option pricing model, which incorporates assumptions and estimates, to measure the fair value of its option awards on the date of grant of each stock option award. Prior to February 2024, the Company had been a private company and lacked company-specific historical and implied volatility information. The Company estimated its expected stock volatility based on an analysis of reported data for a publicly traded peer group of companies that granted options with substantially similar terms and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The expected term assumption for employee grants is determined by using the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is based on the rate of the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends on common stock and does not expect to pay any cash dividends in the foreseeable future. Forfeitures are accounted for as they occur. Recently Adopted Accounting Pronouncements The Company has not adopted any accounting pronouncements during the three months ended March 31, 2024. Recently Issued Accounting Pronouncements The Company has evaluated recently issued accounting pronouncements and determined that there are no such pronouncements that have a material impact on its condensed consolidated financial statements and related disclosures .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of fair value hierarchy utilized to determine such fair values: Fair Value measurements as of Level 1 Level 2 Level 3 Total Assets: Cash equivalents—money market funds $ 64,949 $ — $ — $ 64,949 $ 64,949 $ — $ — $ 64,949 Liabilities: Warrant liabilities, long-term — — 8,798 8,798 Notes payable, long-term — — 28,695 28,695 $ — $ — $ 37,493 $ 37,493 Fair Value measurements as of Level 1 Level 2 Level 3 Total Assets: Cash equivalents—money market funds $ 9,779 $ — $ — $ 9,779 $ 9,779 $ — $ — $ 9,779 Liabilities: Warrant liabilities, current $ — $ — $ 573 $ 573 Warrant liabilities, long-term — — 19,096 19,096 Notes payable, long-term — — 55,152 55,152 $ — $ — $ 74,821 $ 74,821 During the three months ended March 31, 2024 and 2023 , there were no transfers between Level 1, Level 2 and Level 3. See Note 5—“Notes Payable” for the discussion of the fair value methodology of the notes payable and a rollforward of the fair value. See Note 6—“Warrant Liabilities” for the discussion of the fair value methodology of the stock warrants and a rollforward of the fair value.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 2024
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accrued Expenses and Other Current Liabilities	4. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: March 31, December 31, 2024 2023 Payroll and payroll-related expenses $ 4,965 $ 3,500 External research and development services 2,622 1,711 Professional fees and consulting services 967 2,118 Other current liabilities 99 2 $ 8,653 $ 7,331

Notes Payable

Notes Payable	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Notes Payable	5. Notes Payable Notes payable, long-term consisted of the following: March 31, December 31, 2024 2023 2022 Convertible Notes $ — $ 27,162 2023 Notes 28,695 27,990 $ 28,695 $ 55,152 2022 Convertible Notes On January 11, 2022, the Company entered into a financing arrangement with certain lenders (the “2022 Lenders”) in which the Company issued convertible promissory notes in exchange for an aggregate principal amount of $ 20,075 (the “2022 Convertible Notes"). Under the original terms of the 2022 Convertible Notes, interest accrued on the unpaid principal balance of the 2022 Convertible Notes at the rate of 3 % per year until paid or converted in full. Subject to the conversion provisions, all principal and accrued interest on the 2022 Convertible Notes was to be due and payable on July 11, 2023 (the “Original Maturity Date”). On July 11, 2023 (the "reissuance date"), the Company paid $ 78 to settle in full the outstanding principal and accrued interest owed to one of the lenders under the 2022 Convertible Notes and issued amended and restated convertible promissory notes to certain of the lenders (the “Continuing 2022 Lenders”) in replacement of, but not in payment of, the remainder of the 2022 Convertible Notes. As part of these amendments, among other changes, the Continuing 2022 Lenders agreed to extend the maturity date of the outstanding principal and accrued but unpaid interest on the 2022 Convertible Notes to December 31, 2024 . Following these amendments, $ 20,899 in aggregate principal under the 2022 Convertible Notes remained outstanding and accrued interest at the rate of 10 % per year until they were paid or converted in full. In connection with entering into these amendments, the Company issued to the Continuing 2022 Lenders warrants to purchase shares of the Company’s common stock with par value of $ 0.00001 per share. The warrants were recorded as part of the warrant liabilities on the condensed consolidated balance sheet. The Company elected to apply the fair value option ("FVO") to the 2022 Convertible Notes in accordance with ASC 825. Accordingly, the 2022 Convertible Notes are marked to market at the end of each reporting period, with changes in fair value recognized as a component of other income (expense) in the condensed consolidated statements of operations and comprehensive loss. Prior to the Company's IPO in February 2024, the fair value had been estimated using a Monte Carlo simulation model to calculate equity values at different points in time leading up to a conversion event. The Company assessed the assumptions and estimates used in the valuation model at each financial reporting period as additional information impacting the assumptions is obtained. Assumptions and estimates impacting the fair value measurement included the fair value per share of the underlying shares, the expected time to conversion events (IPO or non-IPO), risk-free interest rate, expected volatility of the price of the underlying shares and scenario weightings. The Company determined the fair value per share of the underlying shares by taking into consideration the most recent sales of its convertible preferred stock, results obtained from third-party valuations and additional factors that are deemed relevant. The Company historically had been a private company and lacked company-specific historical and implied volatility information of its stock. Therefore, it estimated its expected stock volatility based on the historical volatility of publicly traded peer companies for a term equal to the expected time to conversion events. The risk-free interest rate was determined by reference to the U.S. Treasury yield curve for time periods approximately equal to the expected time to conversion events. Scenario weightings were based on management's best estimate of the probabilities of the occurrence of each conversion event considered. Upon the closing of the IPO on February 6, 2024, all of the outstanding principal plus accrued interest under the 2022 Convertible Notes were converted into 1,841,321 shares of the Company’s common stock at a conversion price of $ 12.00 per share, which is 80 % of the IPO price of $ 15.00 per share. The 2022 Convertible Notes were marked to market to its fair value as of the time of the conversion before being reclassified to equity. The fair value at the time of the conversion was calculated by multiplying the number of shares of common stock that the 2022 Convertible Notes were converted into by the fair value per share on the conversion date, which is the closing price of the Company's common stock on the NASDAQ Global Market on that date. The following table provides a rollforward of the fair value of the 2022 Convertible Notes: Fair Value Balance as of December 31, 2023 $ 27,162 Decrease in fair value ( 8,012 ) Conversion into common stock ( 19,150 ) Balance as of March 31, 2024 $ — 2023 Notes On September 7, 2023, the Company entered into a credit agreement with certain lenders (the “2023 Lenders”) that provides for term loans in an aggregate principal amount of $ 45,000 (the "Applicable Commitments") in two tranches (the “2023 Notes”). The first tranche with a principal amount of $ 30,000 was extended on September 7, 2023 . The second tranche with a principal amount of $ 15,000 may be extended upon the Company’s achievement of certain funding milestones as defined in the 2023 Notes, by July 31, 2024 . The 2023 Notes also provide for a third tranche with an uncommitted principal amount of $ 20,000 that may be extended to the Company, subject to the lenders’ prior written consent in their sole discretion. The outstanding balances under the 2023 Notes bear interest at a floating annual rate equal to the greater of 5.5 % above the Wall Street Journal prime rate or 13.25 %. On and prior to September 30, 2024, 6.0 % of the interest is payable in kind (the "PIK interest") and added to the outstanding principal amount of the loans. Beginning September 30, 2026, the Company is required to make principal payments in the amount of 1.5 % of the aggregate principal amount outstanding, including accrued PIK interest, each month. The first principal payment date can be extended to September 30, 2027 , at the Company's option, if certain financing milestones as defined in the 2023 Notes are achieved on or prior to September 30, 2026. In addition, upon any principal payment, the Company is required to make an additional payment to the 2023 Lenders a 6.0 % fee (the "Exit Fee") over the principal and accrued PIK interest paid. The aggregate Exit Fee of the 2023 Notes should equal to 6.0 % of the total Applicable Commitments of $ 45,000 plus all accrued PIK interest. All remaining outstanding principal balance, accrued interest and Exit Fee on the 2023 Notes shall be due and payable on the maturity date of September 7, 2028 . In connection with the issuance of the 2023 Notes, the Company issued to the 2023 Lenders warrants to purchase, at the holders’ choice, shares of the Company’s Series F Convertible Preferred Stock, the most senior series of Preferred Stock of the Company that is then authorized, or the Company’s common stock. The warrants were recorded as part of the warrant liabilities on the condensed consolidated balance sheet. The Company elected to apply the FVO to the 2023 Notes in accordance with ASC 825. Accordingly, the 2023 Notes are marked to market at the end of each reporting period, with changes in fair value recognized as a component of other income (expense) in the condensed consolidated statements of operations and comprehensive loss. The fair value was estimated using a discounted cash flow model by discounting projected future cash flows associated with the 2023 Notes to their present value. The discount rate used in the model is based on observable market yields for similarly rated instruments, adjusted for any specific risks inherent in the 2023 Notes. Accrued interest on the 2023 Notes is incorporated into the determination of the fair value of the 2023 Notes. This fair value measurement is based on significant inputs that are not observable in the market and represent a Level 3 measurement. The following table provides a rollforward of the fair value of the 2023 Notes: Fair Value Balance as of December 31, 2023 $ 27,990 Increase in fair value 1,326 Payment of interest ( 621 ) Balance as of March 31, 2024 $ 28,695 The 2023 Notes are subject to specific financial covenants, which include (i) a minimum liquidity covenant that requires the Company to maintain a minimum $ 10,000 balance in cash and/or certain permitted cash equivalent investments, subject to certain exceptions, and (ii) a financing milestone covenant requiring that (a) we have received proceeds from an equity financing or series of financings (including the net proceeds from the IPO) of at least $ 40,000 during the period commencing on September 7, 2023 and ending on or prior to February 15, 2024, and (b) we have received equity financing or series of financings of at least $ 100,000 (inclusive of such equity financing or series of financings in the preceding clause (a)) during the period commencing as of September 7, 2023 and prior to June 30, 2024. In addition, the 2023 Notes also contain customary events of default, subject to rights and remedies generally applicable to federal law or the laws of the State of Delaware. As of March 31, 2024 , the Company was in compliance with the financial covenants and other terms of the arrangement.

Warrant Liabilities

Warrant Liabilities	3 Months Ended
	Mar. 31, 2024
Warrants and Rights Note Disclosure [Abstract]
Warrant Liabilities	6. Warrant Liabilities 2014 Warrant In January 2014, the Company issued a fully vested warrant to purchase 118,483 shares of the Company’s Series B convertible preferred stock (the “2014 Warrant”) in connection with a loan and security agreement entered into in January 2014. The 2014 Warrant was immediately exercisable at an exercise price of $ 1.266 per share and has a contractual term of ten years from issuance. The fair value of the 2014 Warrant at issuance was $ 48 and was recorded as part of the warrant liabilities in the condensed consolidated balance sheet. In January 2024, the 2014 Warrant was amended to extend the expiration date to the earlier of (i) the date that is 30 calendar days after the closing of the Company’s IPO and (ii) July 31, 2024. Upon the closing of the Company's IPO on February 6, 2024, the amended expiration date of the 2014 Warrant was determined to be March 7, 2024. The Company remeasures the fair value of the 2014 Warrant at the end of each reporting period, with any adjustments being recorded as a component of other income (expense) in the condensed consolidated statements of operations and comprehensive loss. Upon the closing of the IPO on February 6, 2024, the warrant to purchase 118,483 shares of the Company's Series B convertible preferred stock was converted to a warrant to purchase 55,211 shares of the Company's common stock. Accordingly, the 2014 Warrant was remeasured upon the closing of the IPO and marked to market to its fair value before being reclassified to equity. The fair value of the 2014 Warrant was determined using the Black-Scholes valuation model with the following assumptions: February 6, December 31, 2024 2023 Risk-free interest rate 4.8 % 4.7 % Expected term (in years) 0.1 0.1 Expected volatility 38 % 47 % Expected dividend yield 0 % 6 % Fair value of common stock per share $ 10.40 — Fair value of Series B convertible preferred stock per share — $ 6.12 This fair value measurement of the 2014 Warrant was based on significant inputs that are not observable in the market and represented a Level 3 measurement. The following table provides a rollforward of the fair value of the Company’s warrant liability: Fair Value Balance as of December 31, 2023 $ 573 Change in fair value ( 148 ) Reclassification to equity ( 425 ) Balance as of March 31, 2024 $ — The 2014 Warrant was fully cashless exercised on the amended expiration date of March 7, 2024, as a result of which a total of 38,544 shares of common stock were issued to the warrant holder. July 2023 Warrants In July 2023, the Company issued fully vested warrants to purchase shares of the Company’s common stock in connection with the issuance of the amended and restated 2022 Convertible Notes (the “July 2023 Warrants”). The July 2023 Warrants were immediately exercisable for a variable number of shares based on the principal amount of the 2022 Convertible Notes, as amended, of $ 20,899 , and an exercise price, at the holders’ choice, of (a) $ 17.9927 per share, (b) the lowest original issue price of shares of Preferred Stock of the Company issued in the Company’s next bona fide private preferred equity financing round, (c) in the event of any convertible note or similar convertible security financing, the conversion price contemplated by such convertible security, or (d) in the event of an IPO, the per share offering price to the public in such IPO. The July 2023 Warrants have a contractual term of ten years from issuance. They were not exercised from their inception through March 31, 2024. The fair value of the July 2023 Warrants at issuance was $ 9,876 and was recorded as part of the warrant liabilities on the condensed consolidated balance sheet. The Company remeasures the fair value at the end of each reporting period, with any adjustments being recorded as a component of other income (expense) in the condensed consolidated statements of operations and comprehensive loss. Prior to the Company's IPO in February 2 024, the fair value was determined using the Monte-Carlo simulation model, which was based on significant inputs that are not observable in the market and represented a Level 3 measurement. After the completion of its IPO, the fair value of the July 2023 Warrants was determined using the Black-Scholes valuation model with the following assumptions: March 31, 2024 Risk-free interest rate 4.2 % Expected term (in years) 9.3 Expected volatility 57 % Expected dividend yield 0 % The following table provides a rollforward of the fair value of the July 2023 Warrants: Fair Value Balance as of December 31, 2023 $ 16,419 Decrease in fair value ( 8,768 ) Balance as of March 31, 2024 $ 7,651 September 2023 Warrants In September 2023, in connection with the issuance of the 2023 Notes, the Company issued fully vested warrants to purchase, at the holders’ choice, shares of the Company’s Series F Convertible Preferred Stock, the most senior series of Preferred Stock of the Company that is then authorized, or the Company’s common stock (the “September 2023 Warrants”). The September 2023 Warrants are immediately exercisable for a variable number of shares based on a total fixed dollar value of $ 4,200 , and an exercise price, at the holders’ choice, of (a) $ 17.9927 per share of common stock or $ 8.3843 per share of Series F Convertible Preferred Stock, (b) the lowest original issue price of any series of Preferred Stock issued by the Company after the issuance date of the September 2023 Warrants, (c) the conversion or exercise price of any convertible debt security, option, or warrant issued by the Company after the issuance date of the September 2023 Warrants, or (d) the price at which the Company’s common equity was first sold to the public by the Company in a firm-commitment underwritten offering or otherwise. The September 2023 Warrants have a contractual term of ten years from issuance. They were not exercised from their inception through March 31, 2024. The fair value of the September 2023 Warrants at issuance was $ 2,592 and was recorded as part of the warrant liabilities on the condensed consolidated balance sheet. The Company remeasures the fair value at the end of each reporting period, with any adjustments being recorded as a component of other income (expense) in the condensed consolidated statements of operations and comprehensive loss. Prior to the Company's IPO in February 2 024, the fair value was determined using the Monte-Carlo simulation model, which was based on significant inputs that are not observable in the market and represented a Level 3 measurement. After the completion of its IPO, the fair value of the September 2023 Warrants was determined using the Black-Scholes valuation model with the following assumptions: March 31, 2024 Risk-free interest rate 4.2 % Expected term (in years) 9.4 Expected volatility 57 % Expected dividend yield 0 % The following table provides a rollforward of the fair value of the September 2023 Warrants: Fair Value Balance as of December 31, 2023 $ 2,677 Decrease in fair value ( 1,530 ) Balance as of March 31, 2024 $ 1,147

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Leases The following table summarizes the future minimum lease payments for operating and finance leases as of March 31, 2024: Year Ending December 31, 2024 (Remaining) $ 3,095 2025 5,441 2026 5,599 2027 5,638 2028 5,749 Thereafter 34,278 Total future minimum lease payments 59,800 Please see Note 7—“Leases” in the Notes to Consolidated Financial Statements included in Item 8 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 for further discussion of the Company's material lease agreements. Guarantees and Indemnification Obligations The Company enters into standard indemnification agreements in the ordinary course of business. Pursuant to these agreements, the Company indemnifies and agrees to reimburse the indemnified party for losses and costs incurred by the indemnified party in connection with any patent, copyright, trade secret or other intellectual property or personal right infringement claim by any third party with respect to the Company’s technology. The term of these indemnification agreements is generally perpetual after execution of the agreement. In addition, the Company has entered into indemnification agreements with members of its board of directors that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of its status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited. To date, the Company has no t incurred any losses or any material costs related to this indemnification obligation and no claims with respect thereto were outstanding. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations and cash flows, and it has no t accrued any liabilities related to such obligations in its condensed consolidated financial statements as of March 31, 2024 and December 31, 2023 .

Convertible Preferred Stock

Convertible Preferred Stock	3 Months Ended
	Mar. 31, 2024
Class of Stock Disclosures [Abstract]
Convertible Preferred Stock	8. Convertible Preferred Stock The Company issued Series A, Series B, Series C-1, Series C-2, Series D, Series E and Series F convertible preferred stock (collectively, the “Convertible Pre ferred Stock”). The holders of Convertible Preferred Stock had liquidation rights in the event of a deemed liquidation that, in certain circumstances, is not solely within the control of the Company. Therefore, the Convertible Preferred Stock was classified outside of stockholders’ deficit at December 31, 2023. The Company had authorized 78,112,639 shares of $ 0.00001 par value convertible preferred stock as of December 31, 2023. Upon the closing of the IPO on February 6, 2024 , all of the Company’s Convertible Preferred Stock shares were automatically converted into 36,343,909 shares of the Company’s common stock. As of December 31, 2023, Convertible Preferred Stock consisted of the following: December 31, 2023 Convertible Convertible Carrying Liquidation Common Series A Convertible Preferred Stock 5,500,000 5,500,000 $ 6,510 $ 9,633 2,562,900 Series B Convertible Preferred Stock 11,451,453 11,332,970 15,459 23,659 5,280,969 Series C-1 Convertible Preferred Stock 9,064,640 9,064,640 20,114 31,644 4,223,960 Series C-2 Convertible Preferred Stock 15,336,464 15,336,464 47,129 70,214 7,146,525 Series D Convertible Preferred Stock 11,994,461 11,994,461 43,899 61,098 5,589,207 Series E Convertible Preferred Stock 12,838,573 12,838,573 54,373 67,527 5,982,550 Series F Convertible Preferred Stock 11,927,048 11,927,048 99,846 115,306 5,557,798 78,112,639 77,994,156 $ 287,330 $ 379,081 36,343,909 In January 2014, the Company issued a fully vested warrant to purchase 118,483 shares of the Company’s Series B Convertible Preferred Stock. In September 2023, the Company issued fully vested warrants to purchase, at the holders’ choice, a variable number of shares of the Company’s Series F Convertible Preferred Stock, the most senior series of Preferred Stock of the Company that is then authorized, or the Company’s common stock. The number of shares exercisable under these warrants is based on a fixed dollar value and an exercise price at the holders’ choice, as defined in the warrant agreement. In March 2024, all the warrants to purchase the Company's Convertible Preferred Stock were converted into warrants to purchase the Company's common stock. Please see Note 10—“Convertible Preferred Stock” in the Notes to Consolidated Financial Statements included in Item 8 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 for further discussion of the convertible preferred stock.

Preferred and Common Stock

Preferred and Common Stock	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Preferred and Common Stock	9. Preferred and Common Stock Preferred Stock On January 26, 2024, the Company's board of directors approved an Amended and Restated Certificate of Incorporation, authorizing the Company to issue 10,000,000 shares of undesignated preferred stock at $ 0.00001 par value per share. There were no shares of such preferred stock outstanding as of March 31, 2024. Common Stock As of December 31, 2023, the Company’s then effective certificate of incorporation, as amended and restated, authorized the Company to issue 107,000,000 shares of $ 0.00001 par value common stock . On January 26, 2024, the Company's board of directors approved an Amended and Restated Certificate of Incorporation, authorizing the Company to issue 300,000,000 shares of common stock at $ 0.00001 par value per share. On January 26, 2024, the Company's board of directors also approved a 1-for- 2.146 reverse stock split of its issued and outstanding shares of common stock. Accordingly, all share and per share amounts for all periods presented in the accompanying unaudited interim condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect the reverse common stock split and adjustment of the Convertible Preferred Stock conversion ratios.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	10. Stock-Based Compensation 2011 Stock Incentive Plan The Company’s 2011 Stock Incentive Plan, as amended, (the “2011 Plan”) provided for the Company to grant restricted stock, restricted stock units, incentive stock options and nonqualified stock options with respect to shares of common stock to employees, officers, directors, consultants and advisors of the Company. Incentive stock options could only be granted to employees. The 2011 Plan is administered by the board of directors, or at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting schedules and other restrictions of awards were determined at the discretion of the board of directors or by a committee of the board of directors if so delegated, except that the exercise price per share of stock options could not be less than 100 % of the fair market value of a share of common stock on the date of grant and the term of stock option could not be greater than ten years . Upon the effective date of the 2024 Incentive Award Plan, as discussed below, the Company ceased granting equity awards under the 2011 Plan. 2024 Incentive Award Plan On January 26, 2024 , the Company's board of directors adopted t he 2024 Incentive Award Plan (the "2024 Plan"), which became effective on February 1, 2024 . The number of shares of the Company's common stock initially reserved for issuance under the 2024 Plan was 4,298,825 shares, which is eligible for an annual increase on the first day of each calendar year beginning on January 1, 2025 and ending on and including January 1, 2034 equal to the lesser of (i) 5 % of the aggregate number of shares of Common Stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of Common Stock as determined by the Board. 2024 Employee Stock Purchase Plan On January 26, 2024 , the Company's board of directors adopted t he 2024 Employee Stock Purchase Plan (the “2024 ESPP Plan”), which became effective on February 1, 2024 . The number of shares of the Company's common stock initially reserved for issuance under the 2024 ESPP Plan was 487,070 shares, which is eligible for an annual increase on the first day of each calendar year beginning on January 1, 2025 and ending on and including January 1, 2034 equal to the lesser of (i) 1 % of the shares of Common Stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of Common Stock as determined by the Board. Stock-Based Compensation Expense The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories within its condensed consolidated statements of operations and comprehensive loss: Three Months Ended March 31, 2024 2023 Research and development $ 1,975 $ 520 Selling, general and administrative 3,242 337 $ 5,217 $ 857 During the year ended December 31, 2023, the Company granted certain restricted stock units which have a one-year cliff vesting with performance conditions based on the timing of occurrence of certain changes in control or financing event. Upon the completion of the Company's IPO in February 2024, the performance condition was achieved, which resulted in $ 2,749 stock-based compensation expense being recognized in the three months ended March 31, 2024. During the three months ended March 31, 2024 , the Company granted to its employees and directors stock options to purchase a total of 2,138,736 shares of common stock, among which options to purchase 1,157,600 shares of common stock were performance-based awards with the number of shares eligible to vest based on the achievement of certain operational metrics. During the three months ended March 31, 2024 , the Company recognized stock-based compensation expense of $ 961 related to these performance-based awards using an accelerated attribution method based on estimated probability of attaining the operational metrics as of March 31, 2024 .

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	11. Net Loss Per Share The following securities that could potentially dilute basic net loss per share in the future were not included in the computation of diluted net loss per share for the periods presented, because to do so would have been antidilutive: Three Months Ended March 31, 2024 2023 Series A Convertible Preferred Stock — 2,562,900 Series B Convertible Preferred Stock — 5,280,969 Series C-1 Convertible Preferred Stock — 4,223,960 Series C-2 Convertible Preferred Stock — 7,146,525 Series D Convertible Preferred Stock — 5,589,207 Series E Convertible Preferred Stock — 5,982,550 Series F Convertible Preferred Stock — 5,557,798 Outstanding stock options 10,634,230 8,917,324 Outstanding restricted stock units 604,509 — Common stock warrants 161,616 161,616 Series B Convertible Preferred Stock warrants — 55,211 Total 11,400,355 45,478,060 The table presented above does not include the number of shares that may be issued upon exercises of the common stock or prefe rred stock warrants issued in connection with the 2022 Convertible Notes and the 2023 Notes because the number of shares to be issued under these warrants are variable based on a variable exercise price at the warrant holders' option.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared by the Company in accordance with accounting principles generally accepted in the United States, or GAAP, for interim financial reporting and as required by Regulation S-X, Rule 10-01. The unaudited interim condensed consolidated financial statements have been prepared in accordance with GAAP and include the accounts of the Company and its wholly owned subsidiary. All intercompany balances and transactions have been eliminated. These interim financial statements, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair presentation of the Company’s financial position and results of operations for the three months ended March 31, 2024 and 2023. The results of operations for the interim periods are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2023 and notes thereto, included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on April 1, 2024. The accompanying unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements.
Use of Estimates	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 condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates relied upon in preparing these condensed consolidated financial statements include, but are not limited to, the fair value of common stock, the fair value of preferred and common stock warrants, the fair value of convertible notes payable, the fair value of stock-based awards, the incremental borrowing rate for lease accounting and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ materially from those estimates.
Deferred Public Offering Costs	Deferred Public Offering Costs Deferred public offering costs, which primarily consist of direct, incremental legal and accounting fees relating to the planned IPO, are capitalized within other long-term assets. The deferred public offering costs are offset against IPO proceeds upon the consummation of the offering. As of December 31, 2023, the Company had deferred offering-related costs of $ 2,180 . Upon closing of the Company’s IPO in February 2024, total deferred offering costs of $ 3,418 were transferred to additional paid-in capital to offset the IPO proceeds. The Company had no deferred offering costs as of March 31, 2024 .
Leases	Leases The Company has entered into operating leases for office and laboratory spaces and finance leases for certain laboratory equipment, which are accounted for in accordance with ASC 842, Leases . The Company determines whether an arrangement is or contains a lease based on the unique facts and circumstances present in the arrangement at inception. Operating leases are included in right-of-use lease assets (“ROU assets”) and current and long-term lease liabilities on the Company’s condensed consolidated balance sheets. Lease expenses for operating leases are recognized on a straight-line basis over the lease term as an operating expense. Assets subject to finance leases are included in property and equipment, net, on the Company’s condensed consolidated balance sheets. Current and long-term portion of the related lease liabilities of the finance leases are included in accrued expenses and other current liabilities and other long-term liabilities, respectively, on the Company’s condensed consolidated balance sheets. Lease expenses for finance leases consist of depreciation of the assets, which is recognized on a straight-line basis over the useful life of the assets as an operating expense, and interest expense using the effective interest method over the lease term. At the lease commencement date, the Company recognizes an ROU asset and a lease liability based on the present value of fixed lease payments over the expected lease term. The Company typically only includes an initial lease term in its assessment of a lease arrangement. Options to renew a lease are not included in the Company’s assessment unless there is a reasonable certainty that the Company will renew. Certain adjustments to the ROU asset may be required for items such as incentives received. The interest rate implicit in the lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments, which reflects the fixed rate at which the Company could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. The Company has elected the short-term lease recognition exemption for short-term leases, which allows the Company not to recognize lease liabilities and ROU assets on the condensed consolidated balance sheets for leases with an original lease term of twelve months or less. Rent expenses for short-term leases are directly expensed as operating expenses in the condensed consolidated statements of operations and comprehensive loss. The Company has elected to not 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 the ROU asset and lease liability. Variable lease costs such as taxes, operating expenses and other expenses are based on actual costs incurred and are directly expensed as operating expenses in the condensed consolidated statements of operations and comprehensive loss. Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including lease modification. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease.
Stock-Based Compensation	Stock-Based Compensation The Company measures all stock options and other stock-based awards based on their fair value on the date of the grant. Those awards typically have a graded vesting schedule and compensation expense for awards with only service conditions is recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the respective award. Compensation costs recognized for performance-based awards reflect the number of awards that are expected to vest during the requisite service period and are recognized using an accelerated attribution method. Upon final determination of the performance conditions achieved, the compensation costs are adjusted to reflect those awards that ultimately vest. Historical performance patterns, to the extent that they are indicative to the performance conditions to be achieved, are used in developing estimates for the probability of attaining these performance conditions. The Company classifies stock-based compensation expense in its condensed consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. Prior to the completion of the Company’s IPO, the Company determined the fair value of the underlying common stock by taking into consideration the results obtained from third-party valuations and additional factors that are deemed relevant, which incorporates significant judgments and estimates. After the completion of the Company’s IPO, the Company considers the fair value of its common stock to equal to the closing price of its common stock traded on the Nasdaq Global Market. The Company uses the Black-Scholes option pricing model, which incorporates assumptions and estimates, to measure the fair value of its option awards on the date of grant of each stock option award. Prior to February 2024, the Company had been a private company and lacked company-specific historical and implied volatility information. The Company estimated its expected stock volatility based on an analysis of reported data for a publicly traded peer group of companies that granted options with substantially similar terms and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The expected term assumption for employee grants is determined by using the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is based on the rate of the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends on common stock and does not expect to pay any cash dividends in the foreseeable future. Forfeitures are accounted for as they occur.
Recently Adopted/Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company has not adopted any accounting pronouncements during the three months ended March 31, 2024. Recently Issued Accounting Pronouncements The Company has evaluated recently issued accounting pronouncements and determined that there are no such pronouncements that have a material impact on its condensed consolidated financial statements and related disclosures

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of fair value hierarchy utilized to determine such fair values: Fair Value measurements as of Level 1 Level 2 Level 3 Total Assets: Cash equivalents—money market funds $ 64,949 $ — $ — $ 64,949 $ 64,949 $ — $ — $ 64,949 Liabilities: Warrant liabilities, long-term — — 8,798 8,798 Notes payable, long-term — — 28,695 28,695 $ — $ — $ 37,493 $ 37,493 Fair Value measurements as of Level 1 Level 2 Level 3 Total Assets: Cash equivalents—money market funds $ 9,779 $ — $ — $ 9,779 $ 9,779 $ — $ — $ 9,779 Liabilities: Warrant liabilities, current $ — $ — $ 573 $ 573 Warrant liabilities, long-term — — 19,096 19,096 Notes payable, long-term — — 55,152 55,152 $ — $ — $ 74,821 $ 74,821

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Accounts Payable and Accrued Liabilities, Current [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: March 31, December 31, 2024 2023 Payroll and payroll-related expenses $ 4,965 $ 3,500 External research and development services 2,622 1,711 Professional fees and consulting services 967 2,118 Other current liabilities 99 2 $ 8,653 $ 7,331

Notes Payable (Tables)

Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2024
Debt Instrument [Line Items]
Schedule of Notes Payable, Long-Term	Notes payable, long-term consisted of the following: March 31, December 31, 2024 2023 2022 Convertible Notes $ — $ 27,162 2023 Notes 28,695 27,990 $ 28,695 $ 55,152
2022 Convertible Notes
Debt Instrument [Line Items]
Schedule of Rollforward of Fair Value of Notes	The following table provides a rollforward of the fair value of the 2022 Convertible Notes: Fair Value Balance as of December 31, 2023 $ 27,162 Decrease in fair value ( 8,012 ) Conversion into common stock ( 19,150 ) Balance as of March 31, 2024 $ —
2023 Notes
Debt Instrument [Line Items]
Schedule of Rollforward of Fair Value of Notes	This fair value measurement is based on significant inputs that are not observable in the market and represent a Level 3 measurement. The following table provides a rollforward of the fair value of the 2023 Notes: Fair Value Balance as of December 31, 2023 $ 27,990 Increase in fair value 1,326 Payment of interest ( 621 ) Balance as of March 31, 2024 $ 28,695

Warrant Liabilities (Tables)

Warrant Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
2014 Warrant
Class of Warrant or Right [Line Items]
Summary of Fair Value of Warrant Determined Using Black Scholes Valuation Model	The fair value of the 2014 Warrant was determined using the Black-Scholes valuation model with the following assumptions: February 6, December 31, 2024 2023 Risk-free interest rate 4.8 % 4.7 % Expected term (in years) 0.1 0.1 Expected volatility 38 % 47 % Expected dividend yield 0 % 6 % Fair value of common stock per share $ 10.40 — Fair value of Series B convertible preferred stock per share — $ 6.12
Summary of Fair Value of Warrant Liability	The following table provides a rollforward of the fair value of the Company’s warrant liability: Fair Value Balance as of December 31, 2023 $ 573 Change in fair value ( 148 ) Reclassification to equity ( 425 ) Balance as of March 31, 2024 $ —
July 2023 Warrants
Class of Warrant or Right [Line Items]
Summary of Fair Value of Warrant Determined Using Black Scholes Valuation Model	Prior to the Company's IPO in February 2 024, the fair value was determined using the Monte-Carlo simulation model, which was based on significant inputs that are not observable in the market and represented a Level 3 measurement. After the completion of its IPO, the fair value of the July 2023 Warrants was determined using the Black-Scholes valuation model with the following assumptions: March 31, 2024 Risk-free interest rate 4.2 % Expected term (in years) 9.3 Expected volatility 57 % Expected dividend yield 0 %
Summary of Fair Value of Warrant Liability	The following table provides a rollforward of the fair value of the July 2023 Warrants: Fair Value Balance as of December 31, 2023 $ 16,419 Decrease in fair value ( 8,768 ) Balance as of March 31, 2024 $ 7,651
September 2023 Warrants
Class of Warrant or Right [Line Items]
Summary of Fair Value of Warrant Determined Using Black Scholes Valuation Model	Prior to the Company's IPO in February 2 024, the fair value was determined using the Monte-Carlo simulation model, which was based on significant inputs that are not observable in the market and represented a Level 3 measurement. After the completion of its IPO, the fair value of the September 2023 Warrants was determined using the Black-Scholes valuation model with the following assumptions: March 31, 2024 Risk-free interest rate 4.2 % Expected term (in years) 9.4 Expected volatility 57 % Expected dividend yield 0 %
Summary of Fair Value of Warrant Liability	The following table provides a rollforward of the fair value of the September 2023 Warrants: Fair Value Balance as of December 31, 2023 $ 2,677 Decrease in fair value ( 1,530 ) Balance as of March 31, 2024 $ 1,147

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Minimum Lease Payments for Operating and Finance Leases	The following table summarizes the future minimum lease payments for operating and finance leases as of March 31, 2024: Year Ending December 31, 2024 (Remaining) $ 3,095 2025 5,441 2026 5,599 2027 5,638 2028 5,749 Thereafter 34,278 Total future minimum lease payments 59,800 Please see Note 7—“Leases” in the Notes to Consolidated Financial Statements included in Item 8 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 for further discussion of the Company's material lease agreements.

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	3 Months Ended
	Mar. 31, 2024
Class of Stock Disclosures [Abstract]
Summary of Convertible Preferred Stock	As of December 31, 2023, Convertible Preferred Stock consisted of the following: December 31, 2023 Convertible Convertible Carrying Liquidation Common Series A Convertible Preferred Stock 5,500,000 5,500,000 $ 6,510 $ 9,633 2,562,900 Series B Convertible Preferred Stock 11,451,453 11,332,970 15,459 23,659 5,280,969 Series C-1 Convertible Preferred Stock 9,064,640 9,064,640 20,114 31,644 4,223,960 Series C-2 Convertible Preferred Stock 15,336,464 15,336,464 47,129 70,214 7,146,525 Series D Convertible Preferred Stock 11,994,461 11,994,461 43,899 61,098 5,589,207 Series E Convertible Preferred Stock 12,838,573 12,838,573 54,373 67,527 5,982,550 Series F Convertible Preferred Stock 11,927,048 11,927,048 99,846 115,306 5,557,798 78,112,639 77,994,156 $ 287,330 $ 379,081 36,343,909

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Summary of Share-Based Compensation Expense Related to Stock Options and Restricted Stock Units	The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories within its condensed consolidated statements of operations and comprehensive loss: Three Months Ended March 31, 2024 2023 Research and development $ 1,975 $ 520 Selling, general and administrative 3,242 337 $ 5,217 $ 857

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Summary of Securities That Could Potentially Dilute Basic Net Loss Per Share in Future Were Not Included in Computation of Diluted Net Loss Per Share	The following securities that could potentially dilute basic net loss per share in the future were not included in the computation of diluted net loss per share for the periods presented, because to do so would have been antidilutive: Three Months Ended March 31, 2024 2023 Series A Convertible Preferred Stock — 2,562,900 Series B Convertible Preferred Stock — 5,280,969 Series C-1 Convertible Preferred Stock — 4,223,960 Series C-2 Convertible Preferred Stock — 7,146,525 Series D Convertible Preferred Stock — 5,589,207 Series E Convertible Preferred Stock — 5,982,550 Series F Convertible Preferred Stock — 5,557,798 Outstanding stock options 10,634,230 8,917,324 Outstanding restricted stock units 604,509 — Common stock warrants 161,616 161,616 Series B Convertible Preferred Stock warrants — 55,211 Total 11,400,355 45,478,060

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	Mar. 05, 2024	Feb. 06, 2024	Mar. 31, 2024	Dec. 31, 2023
Nature of Business and Organization Details [LIne items]
Proceeds from issuance of common stock			$ 103,695
Payments related to offering costs			(2,854)
Offering costs			11,223
Accumulated deficit			349,938	$ 346,616
Cash and cash equivalents			$ 121,441	$ 33,209
Common Stock
Nature of Business and Organization Details [LIne items]
Number of shares issued			7,433,332
IPO | Common Stock
Nature of Business and Organization Details [LIne items]
Number of shares issued	99,999	7,333,333
Sale of stock issue price per share	$ 15	$ 15
Net proceeds from issuance of common stock	$ 1,395	$ 98,882
Proceeds from issuance of common stock	1,500	110,000
Offering costs		3,418
Underwriting discount		$ 7,700
Underwriting discount and commissions	$ 105

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Mar. 31, 2024	Feb. 29, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Deferred offering costs	$ 0	$ 3,418,000	$ 2,180,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value on Recurring Basis - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets:
Assets	$ 64,949	$ 9,779
Liabilities:
Warrant liabilities, current		573
Warrant liabilities, long-term	8,798	19,096
Notes payable, long-term	28,695	55,152
Liabilities	37,493	74,821
Money Market Funds
Assets:
Cash equivalents	64,949	9,779
Level 1
Assets:
Assets	64,949	9,779
Level 1 | Money Market Funds
Assets:
Cash equivalents	64,949	9,779
Level 3
Liabilities:
Warrant liabilities, current		573
Warrant liabilities, long-term	8,798	19,096
Notes payable, long-term	28,695	55,152
Liabilities	$ 37,493	$ 74,821

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Transfers between level 1, level 2 and level 3	$ 0	$ 0

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Accounts Payable and Accrued Liabilities, Current [Abstract]
Payroll and payroll-related expenses	$ 4,965	$ 3,500
External research and development services	2,622	1,711
Professional fees and consulting services	967	2,118
Other current liabilities	99	2
Accrued expenses and other current liabilities	$ 8,653	$ 7,331

Notes Payable - Schedule of Not

Notes Payable - Schedule of Notes Payable, Long-Term (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
2022 Convertible Notes		$ 27,162
2023 Notes	$ 28,695	27,990
Notes payable, long-term	$ 28,695	$ 55,152

Notes Payable - Additional Info

Notes Payable - Additional Information (Details) - USD ($)					3 Months Ended	5 Months Ended	10 Months Ended
	Feb. 06, 2024	Sep. 07, 2023	Jul. 11, 2023	Jan. 11, 2022	Mar. 31, 2024	Feb. 15, 2024	Jun. 29, 2024	Jan. 26, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Common stock, Par value					$ 0.00001			$ 0.00001	$ 0.00001
Outstanding principal amount									$ 27,162,000
Cash and/or certain permitted cash equivalent investments					$ 121,441,000				$ 33,209,000
2022 Convertible Notes
Debt Instrument [Line Items]
Convertible notes converted into common stock	1,841,321
Convertible price	$ 12
Percentage of initial public offering per share	80%
Price per share	$ 15
Amount paid off			$ 78,000
Principal amount				$ 20,075,000
Interest accrued on the unpaid principal balance, Rate				3%
Original maturity date				Jul. 11, 2023
2022 Convertible Notes | After Amendments
Debt Instrument [Line Items]
Common stock, Par value				$ 0.00001
Extended maturity date			Dec. 31, 2024
Outstanding principal amount					$ 20,899,000
Interest rate upon amendments					10%
2023 Notes
Debt Instrument [Line Items]
Interest rate		13.25%
Interest rate terms		The outstanding balances under the 2023 Notes bear interest at a floating annual rate equal to the greater of 5.5% above the Wall Street Journal prime rate or 13.25%.
Principal amount		$ 45,000,000
Financial covenants, Description					The 2023 Notes are subject to specific financial covenants, which include (i) a minimum liquidity covenant that requires the Company to maintain a minimum $10,000 balance in cash and/or certain permitted cash equivalent investments, subject to certain exceptions, and (ii) a financing milestone covenant requiring that (a) we have received proceeds from an equity financing or series of financings (including the net proceeds from the IPO) of at least $40,000 during the period commencing on September 7, 2023 and ending on or prior to February 15, 2024, and (b) we have received equity financing or series of financings of at least $100,000 (inclusive of such equity financing or series of financings in the preceding clause (a)) during the period commencing as of September 7, 2023 and prior to June 30, 2024. In addition, the 2023 Notes also contain customary events of default, subject to rights and remedies generally applicable to federal law or the laws of the State of Delaware.
Financial covenants, Compliance					As of March 31, 2024, the Company was in compliance with the financial covenants and other terms of the arrangement.
First principal payment date		Sep. 30, 2027
Maturity date		Sep. 07, 2028
Exit fee percentage		6%
2023 Notes | On and prior to September 30, 2024
Debt Instrument [Line Items]
Interest rate paid in kind		6%
2023 Notes | Beginning September 30, 2026
Debt Instrument [Line Items]
Periodic payment percentage of principal		1.50%
2023 Notes | Minimum
Debt Instrument [Line Items]
Cash and/or certain permitted cash equivalent investments					$ 10,000,000
Proceeds from equity financing or series of financings						$ 40,000,000
2023 Notes | Minimum | Scenario Forecast
Debt Instrument [Line Items]
Proceeds from equity financing or series of financings							$ 100,000,000
2023 Notes | First Tranche
Debt Instrument [Line Items]
Principal amount		$ 30,000,000
First principal payment date		Sep. 07, 2023
2023 Notes | Second Tranche
Debt Instrument [Line Items]
Principal amount		$ 15,000,000
First principal payment date		Jul. 31, 2024
2023 Notes | Third Tranche
Debt Instrument [Line Items]
Principal amount		$ 20,000,000
2023 Notes | Wall Street Journal Prime Rate
Debt Instrument [Line Items]
Interest rate margin		5.50%

Notes Payable - Schedule of Rol

Notes Payable - Schedule of Rollforward of Fair Value of 2022 Convertible Notes (Details) - Level 3 - 2022 Convertible Notes $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	$ 27,162
Decrease in fair value	(8,012)
Conversion into common stock	(19,150)
Balance	$ 0

Notes Payable - Schedule of R_2

Notes Payable - Schedule of Rollforward of Fair Value of 2023 Notes (Details) - Level 3 - 2023 Notes $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	$ 27,990
Increase in fair value	1,326
Payment of interest	(621)
Balance	$ 28,695

Warrant Liabilities - Additiona

Warrant Liabilities - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 31, 2024	Feb. 06, 2024	Sep. 30, 2023	Jul. 31, 2023	Jan. 31, 2014
2014 Warrant
Class of Warrant or Right [Line Items]
Warrant purchase		118,483			118,483
Convertible preferred stock converted to warrant		55,211
Exercise price of warrants					$ 1.266
Warrant liabilities					$ 48
Issuance of shares	38,544
July 2023 Warrants
Class of Warrant or Right [Line Items]
Principal amount of convertible notes				$ 20,899
Exercise price of warrants				$ 17.9927
Warrant liabilities				$ 9,876
September 2023 Warrants
Class of Warrant or Right [Line Items]
Immediately exercisable warrants amount			$ 4,200
Warrant liabilities			$ 2,592
September 2023 Warrants | Series F Convertible Preferred Stock
Class of Warrant or Right [Line Items]
Exercise price of warrants			$ 8.3843
September 2023 Warrants | Common Stock
Class of Warrant or Right [Line Items]
Exercise price of warrants			$ 17.9927

Warrant Liabilities - Summary o

Warrant Liabilities - Summary of Fair Value of Warrant Determined Using Black Scholes Valuation Model (Details) - $ / shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
2014 Warrant
Class of Warrant or Right [Line Items]
Risk-free interest rate	4.80%	4.70%
Expected term (in years)	1 month 6 days	1 month 6 days
Expected volatility	38%	47%
Expected dividend yield	0%	6%
Fair value of common stock per share	$ 10.4	$ 0
Fair value of Series B convertible preferred stock per share	$ 0	$ 6.12
July 2023 Warrants
Class of Warrant or Right [Line Items]
Risk-free interest rate	4.20%
Expected term (in years)	9 years 3 months 18 days
Expected volatility	57%
Expected dividend yield	0%
September 2023 Warrants
Class of Warrant or Right [Line Items]
Risk-free interest rate	4.20%
Expected term (in years)	9 years 4 months 24 days
Expected volatility	57%
Expected dividend yield	0%

Warrant Liabilities - Summary_2

Warrant Liabilities - Summary of Fair Value of warrant liability (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Class of Warrant or Right [Line Items]
Change/Decrease in fair value	$ 10,446	$ (5)
2014 Warrant
Class of Warrant or Right [Line Items]
Beginning balance	573
Change/Decrease in fair value	(148)
Reclassification to equity	(425)
Ending balance	0
July 2023 Warrants
Class of Warrant or Right [Line Items]
Beginning balance	16,419
Change/Decrease in fair value	(8,768)
Ending balance	7,651
September 2023 Warrants
Class of Warrant or Right [Line Items]
Beginning balance	2,677
Change/Decrease in fair value	(1,530)
Ending balance	$ 1,147

Commitments and Contingencies -

Commitments and Contingencies - Summary of Future Minimum Lease Payments for Operating and Finance Leases (Details) $ in Thousands	Mar. 31, 2024 USD ($)
Operating Lease
2024 (Remaining)	$ 3,095
2025	5,441
2026	5,599
2027	5,638
2028	5,749
Thereafter	34,278
Total future minimum lease payments	59,800
Finance Lease
2024 (Remaining)	3,095
2025	5,441
2026	5,599
2027	5,638
2028	5,749
Thereafter	34,278
Total future minimum lease payments	$ 59,800

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Loss or material costs related to indemnification obligation	$ 0
Claims outstanding	0
Liabilities related to obligation	$ 0	$ 0

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Iformation (Details) - $ / shares	Feb. 06, 2024	Mar. 31, 2024	Dec. 31, 2023	Jan. 31, 2014
Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized		0	78,112,639
Convertible preferred stock, par value		$ 0.00001	$ 0.00001
IPO closing date	Feb. 06, 2024
Shares converted	36,343,909
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized			5,500,000
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized			11,451,453
Issued fully vested warrant to purchase convertible preferred stock				118,483
Series C-1 Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized			9,064,640
Series C-2 Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized			15,336,464
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized			11,994,461
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized			12,838,573
Series F Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized			11,927,048

Convertible Preferred Stock - S

Convertible Preferred Stock - Summary of Convertible Preferred Stock (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2022
Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	78,112,639	0
Convertible preferred shares issued	77,994,156	0
Convertible preferred shares outstanding	77,994,156	0	77,994,156	77,994,156
Carrying value	$ 287,330		$ 287,330	$ 287,330
Liquidation preference	$ 379,081	$ 0
Common stock issuable upon conversion	36,343,909
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	5,500,000
Convertible preferred shares issued	5,500,000
Convertible preferred shares outstanding	5,500,000
Carrying value	$ 6,510
Liquidation preference	$ 9,633
Common stock issuable upon conversion	2,562,900
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	11,451,453
Convertible preferred shares issued	11,332,970
Convertible preferred shares outstanding	11,332,970
Carrying value	$ 15,459
Liquidation preference	$ 23,659
Common stock issuable upon conversion	5,280,969
Series C-1 Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	9,064,640
Convertible preferred shares issued	9,064,640
Convertible preferred shares outstanding	9,064,640
Carrying value	$ 20,114
Liquidation preference	$ 31,644
Common stock issuable upon conversion	4,223,960
Series C-2 Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	15,336,464
Convertible preferred shares issued	15,336,464
Convertible preferred shares outstanding	15,336,464
Carrying value	$ 47,129
Liquidation preference	$ 70,214
Common stock issuable upon conversion	7,146,525
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	11,994,461
Convertible preferred shares issued	11,994,461
Convertible preferred shares outstanding	11,994,461
Carrying value	$ 43,899
Liquidation preference	$ 61,098
Common stock issuable upon conversion	5,589,207
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	12,838,573
Convertible preferred shares issued	12,838,573
Convertible preferred shares outstanding	12,838,573
Carrying value	$ 54,373
Liquidation preference	$ 67,527
Common stock issuable upon conversion	5,982,550
Series F Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred shares authorized	11,927,048
Convertible preferred shares issued	11,927,048
Convertible preferred shares outstanding	11,927,048
Carrying value	$ 99,846
Liquidation preference	$ 115,306
Common stock issuable upon conversion	5,557,798

Preferred and Common Stock - Ad

Preferred and Common Stock - Additional information (Details)		3 Months Ended
	Jan. 26, 2024 $ / shares shares	Mar. 31, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares
Class of Stock Disclosures [Abstract]
Preferred stock, shares authorized	10,000,000	10,000,000	0
Preferred stock, par value | $ / shares	$ 0.00001	$ 0.00001	$ 0.00001
Preferred stock, shares outstanding		0	0
Common stock, shares authorized	300,000,000	300,000,000	107,000,000
Common stock, par value | $ / shares	$ 0.00001	$ 0.00001	$ 0.00001
Reverse stock split, description		1-for-2.146 reverse stock split
Reverse stock split conversion ratio	0.466

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Thousands				3 Months Ended
	Feb. 06, 2024	Feb. 01, 2024	Jan. 26, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares issued				47,896,908		2,105,815
Stock-based compensation expense recognized				$ 2,749
Number of Shares, Grant				2,138,736
Stock-based compensation expense				$ 5,217	$ 857
Performance-Based Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares, Grant				1,157,600
Stock-based compensation expense				$ 961
2011 Stock Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Exercise price per share of stock options as percentage of fair market value of common stock				100%
Expected term of stock option				10 years
2024 Incentive Award Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Plan adoption date			Jan. 26, 2024
Plan effective date		Feb. 01, 2024
Percentage of common stock shares outstanding	5%
Number of common stock reserved for issuance			4,298,825
2024 Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Plan adoption date			Jan. 26, 2024
Plan effective date		Feb. 01, 2024
Percentage of common stock shares outstanding	1%
Number of common stock reserved for issuance	487,070

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Share-Based Compensation Expense Related to Stock Options and Restricted Stock Units (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 5,217	$ 857
Research and Development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	1,975	520
Selling, General and Administrative
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 3,242	$ 337

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Securities That Could Potentially Dilute Basic Net Loss Per Share in Future Were Not Included in Computation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares	11,400,355	45,478,060
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		2,562,900
Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		5,280,969
Series C-1 Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		4,223,960
Series C-2 Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		7,146,525
Series D Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		5,589,207
Series E Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		5,982,550
Series F Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		5,557,798
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares	10,634,230	8,917,324
Outstanding Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares	604,509
Common Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares	161,616	161,616
Series B Convertible Preferred Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares		55,211