Lexeo Therapeutics, Inc. Common Stock (LXEO) 10-Q 13 Nov 24 2024 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2024	Nov. 11, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Entity Registrant Name	Lexeo Therapeutics, Inc.
Entity Central Index Key	0001907108
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity File Number	001-41855
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-4012572
Entity Address, Address Line One	345 Park Avenue South
Entity Address, Address Line Two	Floor 6
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10010
City Area Code	212
Local Phone Number	547-9879
Entity Small Business	true
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common Stock ($0.0001 par value)
Trading Symbol	LXEO
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		33,065,947

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 157,020	$ 121,466
Prepaid expenses and other current assets	2,438	2,828
Total current assets	159,458	124,294
Restricted cash	3,252	3,252
Property and equipment, net	1,180	1,056
Lease right-of-use assets - finance, net	1,540	1,763
Lease right-of-use assets - operating	8,435	9,442
Total assets	173,865	139,807
Current liabilities:
Accounts payable	8,438	3,794
Accrued expenses and other current liabilities	15,698	10,840
Current portion of lease liabilities - finance	574	518
Current portion of lease liabilities - operating	2,108	2,087
Total current liabilities	26,818	17,239
Non-current liabilities
Non-current portion of lease liabilities - finance	930	1,247
Non-current portion of lease liabilities - operating	6,791	7,786
Total liabilities	34,539	26,272
Commitments and contingencies (Note 11)
Stockholders' and members' deficit:
Common stock, $0.0001 par value, 500,000,000 shares authorized as of September 30, 2024; 33,070,045 shares issued and 33,058,447 shares outstanding as of September 30, 2024; 500,000,000 shares authorized as of December 31, 2023; 26,668,485 shares issued and 26,646,378 shares outstanding as of December 31, 2023	3	3
Treasury stock, at cost, 2,991 common shares at September 30, 2024 and 0 common shares at December 31, 2023	(13)
Additional paid-in capital	393,585	295,372
Accumulated deficit	(254,249)	(181,840)
Total stockholders' equity	139,326	113,535
Total liabilities and stockholders' equity	$ 173,865	$ 139,807

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2024	Dec. 31, 2023
Common stock, par value per share	$ 0.0001	$ 0.0001
Common stock, Authorized	500,000,000	500,000,000
Common Stock, Shares issued	33,070,045	26,668,485
Common stock, Outstanding	33,058,447	26,646,378
Treasury stock, common shares	2,991	0

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating expenses
Research and development expenses	$ 23,423	$ 17,246	$ 55,725	$ 44,920
General and administrative	8,120	3,027	22,659	8,619
Total operating expenses	31,543	20,273	78,384	53,539
Operating loss	(31,543)	(20,273)	(78,384)	(53,539)
Other income and expense
Loss on fair value adjustment to convertible SAFE Note		(272)		(272)
Other income (expense), net	(3)	1	(9)	(6)
Interest expense	(35)	(52)	(107)	(155)
Interest income	2,092	488	6,091	1,765
Total other income and expense	2,054	165	5,975	1,332
Loss from operations before income taxes	(29,489)	(20,108)	(72,409)	(52,207)
Net loss and comprehensive loss	$ (29,489)	$ (20,108)	$ (72,409)	$ (52,207)
Net loss per common share, basic	$ (0.89)	$ (12.36)	$ (2.31)	$ (32.24)
Net loss per common share, diluted	$ (0.89)	$ (12.36)	$ (2.31)	$ (32.24)
Weighted average number of shares outstanding used in computation of net loss per common share, basic	33,063,153	1,626,734	31,354,821	1,619,152
Weighted average number of shares outstanding used in computation of net loss per common share, diluted	33,063,153	1,626,734	31,354,821	1,619,152

Condensed Consolidated Statemen

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Deficit
Temporary equity, balance, shares at Dec. 31, 2022		143,653,545
Temporary equity, balance, value at Dec. 31, 2022		$ 185,033
Balance, shares at Dec. 31, 2022			1,607,185
Balance, value at Dec. 31, 2022	$ (112,954)				$ 2,492	$ (115,446)
Exercise of stock options, shares			1,494
Exercise of stock options, value	12				12
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, net of proceeds received from early exercise of unvested stock options subject to repurchase and recorded as deposit liabilities, share			5,325
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, net of proceeds received from early exercise of unvested stock options subject to repurchase and recorded as deposit liabilities, value	21				21
Stock-based compensation expense	397				397
Net loss	(18,658)					(18,658)
Temporary equity, balance, shares at Mar. 31, 2023		143,653,545
Temporary equity, balance, value at Mar. 31, 2023		$ 185,033
Balance, shares at Mar. 31, 2023			1,614,004
Balance, value at Mar. 31, 2023	(131,182)				2,922	(134,104)
Temporary equity, balance, shares at Dec. 31, 2022		143,653,545
Temporary equity, balance, value at Dec. 31, 2022		$ 185,033
Balance, shares at Dec. 31, 2022			1,607,185
Balance, value at Dec. 31, 2022	(112,954)				2,492	(115,446)
Net loss	(52,207)
Temporary equity, balance, shares at Sep. 30, 2023		143,653,545
Temporary equity, balance, value at Sep. 30, 2023		$ 185,033
Balance, shares at Sep. 30, 2023			1,633,206
Balance, value at Sep. 30, 2023	(162,808)				4,845	(167,653)
Temporary equity, balance, shares at Dec. 31, 2022		143,653,545
Temporary equity, balance, value at Dec. 31, 2022		$ 185,033
Balance, shares at Dec. 31, 2022			1,607,185
Balance, value at Dec. 31, 2022	(112,954)				2,492	(115,446)
Net loss	(66,400)
Balance, shares at Dec. 31, 2023			26,646,378
Balance, value at Dec. 31, 2023	113,535		$ 3		295,372	(181,840)
Temporary equity, balance, shares at Mar. 31, 2023		143,653,545
Temporary equity, balance, value at Mar. 31, 2023		$ 185,033
Balance, shares at Mar. 31, 2023			1,614,004
Balance, value at Mar. 31, 2023	(131,182)				2,922	(134,104)
Exercise of stock options, shares			2,342
Exercise of stock options, value	9				9
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase. Shares			5,708
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Value	26				26
Stock-based compensation expense	969				969
Net loss	(13,441)					(13,441)
Temporary equity, balance, shares at Jun. 30, 2023		143,653,545
Temporary equity, balance, value at Jun. 30, 2023		$ 185,033
Balance, shares at Jun. 30, 2023			1,622,054
Balance, value at Jun. 30, 2023	(143,619)				3,926	(147,545)
Exercise of stock options, shares			8,080
Exercise of stock options, value	30				30
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase. Shares			3,072
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Value	16				16
Stock-based compensation expense	873				873
Net loss	(20,108)					(20,108)
Temporary equity, balance, shares at Sep. 30, 2023		143,653,545
Temporary equity, balance, value at Sep. 30, 2023		$ 185,033
Balance, shares at Sep. 30, 2023			1,633,206
Balance, value at Sep. 30, 2023	(162,808)				4,845	(167,653)
Balance, shares at Dec. 31, 2023			26,646,378
Balance, value at Dec. 31, 2023	113,535		$ 3		295,372	(181,840)
Exercise of stock options, shares			942
Exercise of stock options, value	10				10
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, net of proceeds received from early exercise of unvested stock options subject to repurchase and recorded as deposit liabilities, share			1,916
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, net of proceeds received from early exercise of unvested stock options subject to repurchase and recorded as deposit liabilities, value	3				3
Issuance of common stock upon private placement offering, Shares			6,278,905
Issuance of common stock upon private placement offering, Value	88,753				88,753
Stock-based compensation expense	2,331				2,331
Net loss	(21,682)					(21,682)
Balance, shares at Mar. 31, 2024			32,928,141
Balance, value at Mar. 31, 2024	182,950		$ 3		386,469	(203,522)
Balance, shares at Dec. 31, 2023			26,646,378
Balance, value at Dec. 31, 2023	113,535		$ 3		295,372	(181,840)
Net loss	$ (72,409)
Balance, shares at Sep. 30, 2024	33,058,447
Balance, value at Sep. 30, 2024	$ 139,326		$ 3	$ (13)	393,585	(254,249)
Balance, shares at Mar. 31, 2024			32,928,141
Balance, value at Mar. 31, 2024	182,950		$ 3		386,469	(203,522)
Exercise of stock options, shares			108,912
Exercise of stock options, value	419				419
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase. Shares			5,849
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Value	26				26
Additional offering costs incurred related to issuance of common stock upon private placement offering	(42)				(42)
Treasury stock repurchase, Shares			(2,991)
Treasury stock repurchase, Value	(13)			(13)
Stock-based compensation expense	2,846				2,846
Net loss	(21,238)					(21,238)
Balance, shares at Jun. 30, 2024			33,039,911
Balance, value at Jun. 30, 2024	164,948		$ 3	(13)	389,718	(224,760)
Exercise of stock options, shares			15,792
Exercise of stock options, value	39				39
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase. Shares			2,744
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, Value	14				14
Additional offering costs incurred related to issuance of common stock upon private placement offering	24				24
Stock-based compensation expense	3,790				3,790
Net loss	$ (29,489)					(29,489)
Balance, shares at Sep. 30, 2024	33,058,447
Balance, value at Sep. 30, 2024	$ 139,326		$ 3	$ (13)	$ 393,585	$ (254,249)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Commissions and Offering Costs
Net of issuance costs	$ 6,246

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net loss	$ (72,409)	$ (52,207)
Adjustments to reconcile net loss to net cash used in operating activities:
Reduction in the carrying amount of ROU assets, operating	1,007	932
Reduction in the carrying amount of ROU assets, finance	245	227
Stock based compensation expense	8,967	2,239
Depreciation and amortization expense	229	194
Change in fair value of convertible SAFE Note liability		272
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	390	292
Accounts payable	4,420	(574)
Accrued expenses and other current liabilities	5,289	4,211
Lease liabilities, operating	(974)	(1,096)
Lease liabilities, finance	11	(5)
Net cash used in operating activities	(52,825)	(45,515)
Cash flows from investing activities:
Purchase of internal use software	(13)	(50)
Purchase of property and equipment	(481)	(42)
Net cash used in investing activities	(494)	(92)
Cash flows from financing activities:
Proceeds from exercise of stock options	468	51
Payments on finance leases	(294)	(320)
Treasury stock repurchase	(13)
Payments of issuance costs on convertible SAFE Note		(11)
Proceeds from issuance of convertible SAFE Note		4,000
Proceeds from issuance of common stock upon private placement offering, net of commissions and offering costs	88,712
Net cash provided by financing activities	88,873	3,720
Net change in cash, cash equivalents and restricted cash	35,554	(41,887)
Cash, cash equivalents and restricted cash at beginning of period	124,718	80,588
Cash, cash equivalents and restricted cash at end of period	160,272	38,701
Supplemental disclosure of non-cash activities
Deferred offering costs included in accounts payable and accrued expenses		1,004
Issuance costs related to convertible debt included in accounts payable and accrued expenses		125
(Property and equipment purchased in the prior period and paid in the current period), net of property and equipment purchased in the current period included in accounts payable and accrued expenses	(141)	73
Finance lease right-of use assets and finance lease liabilities recognized	22
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, (net of proceeds received from early exercise of unvested stock options subject to repurchase and recorded as deposit liabilities)	$ 42	$ 63

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (29,489)	$ (21,238)	$ (21,682)	$ (20,108)	$ (13,441)	$ (18,658)	$ (72,409)	$ (52,207)	$ (66,400)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During our last fiscal quarter, the following officer, as defined in Rule 16a-1(f), adopted a “Rule 10b5-1 trading arrangement” as defined in Regulation S-K Item 408, as follows: On August 30, 2024 , R. Nolan Townsend , our Chief Executive Officer and a member of our board of directors , adopted a Rule 10b5-1 trading arrangement providing for the sale from time to time of an aggregate of up to 115,000 shares of common stock, commencing on January 2, 2025. The trading arrangement is intended to satisfy the affirmative defense in Rule 10b5-1(c). The duration of the trading arrangement is until August 15, 2025 , or earlier if all transactions under the trading arrangement are completed. No other officers, as defined in Rule 16a-1(f), or directors adopted or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” as defined in Regulation S-K Item 408, during the last fiscal quarter.
R. Nolan Townsend
Trading Arrangements, by Individual
Name	R. Nolan Townsend
Title	Chief Executive Officer and a member of our board of directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	August 30, 2024
Expiration Date	August 15, 2025
Aggregate Available	115,000
All Other Officers
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

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Description of Business —Lexeo Therapeutics, Inc. (the “Company”) is a clinical stage genetic medicine company with a focus on hereditary and acquired diseases of high unmet need. The Company’s investigational therapies have the potential to offer gene therapy-based treatments to address many diseases that have eluded today’s existing drug delivery platforms. The Company utilizes adeno-associated viruses (“AAV”) that have been engineered to transfer genes to patients. The Company’s therapeutic investigational treatments include gene therapies primarily in the early clinical and late pre-clinical stages of research and development. The Company is located in New York, NY and was first formed on February 17, 2017, as an LLC under the laws of the State of Delaware under the legal name Lexeo Therapeutics, LLC. The Company filed and executed a certificate of conversion to corporation on November 20, 2020, to convert the LLC to Lexeo Therapeutics, Inc, a Delaware corporation. All of the Company’s tangible assets are held in the United States (“U.S.”). Basis of Presentation and Principles of Consolidation —The Company’s fiscal year ends on December 31, and its fiscal quarters end on March 31, June 30, and September 30. These unaudited condensed financial statements and accompanying notes reflect the operations of the Company that have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. These unaudited condensed financial statements and accompanying notes should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2023 (the “Annual Financial Statements”) included in the Company's Annual Report on Form 10-K, filed with the United States Securities and Exchange Commission on March 11, 2024. The unaudited condensed balance sheet at December 31, 2023 has been derived from the audited consolidated financial statements at that date. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary to present fairly the financial position of the Company and its results of operations and cash flows for the periods presented have been included. Operating results for the three and nine months ended September 30, 2024 are not necessarily indicative of the results that may be expected for the year ending December 31, 2024, for any other interim period, or for any other future year. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). The Company has no unconsolidated subsidiaries. Certain prior period balances have been reclassified to conform to the current period presentation. A 10.594230-for-1 reverse share split of the Company’s series A convertible preferred stock, series B convertible preferred stock, common stock, and options to purchase common stock under the Company’s 2021 Equity Incentive Plan (as defined in Note 8), as well as corresponding adjustments in the respective conversion prices of the series A convertible preferred stock and series B convertible preferred stock, was effected on October 13, 2023 as approved by the Company’s board of directors (the "Board of Directors") and its shareholders (the “Stock Split”). The Stock Split reduced the number of shares of the Company’s authorized, issued and outstanding common stock, as well as the numbers of shares reserved and available for future issuance and underlying outstanding options to purchase common stock under its 2021 Equity Incentive Plan, on a 10.594230-for-1 basis. As such, all references to series A convertible preferred stock and series B convertible preferred stock conversion ratios, conversion share and per share amounts, and post- conversion share and per share amounts, as well as common stock option, option per common share, common share and common per share amounts, in these unaudited condensed financial statements and accompanying notes have been retroactively restated to reflect the Stock Split and the Stock Split’s effect on the respective series A convertible preferred stock and series B convertible preferred stock conversion ratios for each series of convertible preferred stock. The Stock Split did not affect the par values per share. Need for Additional Capital —Since inception, the Company has incurred net losses and negative cash flows from operations, including net losses of $ 72.4 million and $ 66.4 million during the nine months ended September 30, 2024 and the year ended December 31, 2023, respectively. As of September 30, 2024, the Company had cash and cash equivalents of $ 157.0 million and an accumulated deficit of $ 254.2 million and expects to incur substantial operating losses and negative cash flows from operations for the foreseeable future. During the years ended December 31, 2021 and December 31, 2020, the Company raised aggregate total net proceeds of $ 185.0 million in connection with the issuance of series A and series B convertible preferred stock. During the year ended December 31, 2023 the Company raised $ 100.3 million of total net proceeds in connection with the closing of its initial public offering ("IPO") on November 7, 2023 and subsequent partial exercise of the underwriters' option to purchase additional shares, as well $ 3.9 million of net proceeds from the issuance of a convertible Simple Agreement for Future Equity (“SAFE”) note (the "convertible SAFE Note") in August 2023. During the nine months ended September 30, 2024, the Company received total net proceeds of $ 88.7 million after deducting underwriting commissions and offering expenses in a private placement offering of its common stock (see Note 8). Management estimates that the Company's current cash and cash equivalents balance is sufficient to fund its operations for at least 12 months from the issuance date of these unaudited condensed financial statements. If the Company is unable to obtain additional funding before achieving sufficient profitability and positive cash flows from operations, if ever, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue plans to obtain additional funding before achieving sufficient profitability and positive cash flows from operations, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. Risks and Uncertainties —The Company is subject to risks and uncertainties common to early-stage companies in the biopharmaceutical industry, including, but not limited to, successful discovery and development of its product candidates, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, protection of proprietary technology, compliance with governmental regulations, the ability to secure additional capital to fund operations, and commercial success of its product candidates. Any of the Company’s current product candidates and future product candidates that it may develop will require extensive nonclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel, infrastructure, and extensive compliance- reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies There have been no significant changes in the Company’s accounting policies from those disclosed in its Annual Financial Statements. Use of Estimates —The preparation of the financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to the accruals of research and development costs, including accruals of research contract costs, and assumptions used to estimate the fair value of the Company’s stock option awards and, prior to its IPO, to determine the fair value of its common stock. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when facts and circumstances dictate. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates. Net Loss per Share— The Company follows the two-class method when computing net income (loss) per common share as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (loss) per common share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company considers its convertible preferred stock to be participating securities as, in the event a dividend is paid on common stock, the holders of these securities would be entitled to receive dividends on a basis consistent with the common stockholders. The Company also considers the shares issued upon the early exercise of stock options that are subject to repurchase to be participating securities because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. There is no allocation required under the two-class method during periods of loss since the participating securities do not have a contractual obligation to share in the losses of the Company. Basic net income (loss) per common share is computed by dividing the net income (loss) per common share by the weighted-average number of common shares outstanding for the period. Diluted net income (loss) per common share is computed by adjusting net income (loss) to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per common share is computed by dividing the diluted net loss by the weighted-average number of common shares outstanding for the period, including potential dilutive common shares. For the purposes of this calculation, shares of convertible preferred stock are considered potential dilutive common shares. In periods in which the Company reported a net loss, diluted net loss per common share was the same as basic net loss per common share since dilutive common shares were not assumed to have been issued if their effect was anti-dilutive. During (i) the three and nine months ended September 30, 2023, 8,070,027 potential common shares related to the conversion of series A convertible preferred stock and 5,489,573 potential common shares related to the conversion of series B convertible preferred stock, which converted into 8,070,027 common shares and 6,386,337 common shares, respectively, in connection with the Company’s IPO on November 7, 2023 (see Note 8), and 2,322,843 potential common shares related to the exercise of outstanding stock options, and (ii) the three and nine months ended September 30, 2024, 3,744,541 total potential common shares related to the exercise of outstanding stock options and settlement of outstanding restricted stock units ("RSUs") (see Note 9), were excluded from the computation of diluted net loss per common share because including them would have had an anti-dilutive effect as the Company reported net losses for those periods. Concentrations of Credit Risk —Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and restricted cash. The Company’s cash and restricted cash balances exceed Federal Deposit Insurance Corporation insurance limits, and the Company’s cash equivalents consist of investments in a U.S. government money market fund. The Company’s cash and cash equivalents and restricted cash is held with large financial institutions that management believes to be of high credit quality. To date, the Company has no t recognized any losses caused by uninsured balances.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The three levels of inputs that may be used to measure fair value are as follows: Level 1 —Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 —Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 —Inputs are unobservable inputs for the asset or liability. The Company’s cash equivalents consist of investments in a U.S. government money market fund stated at carrying value, which approximates fair value and is based on quoted prices in active markets for identical securities. Cash is stated at carrying value, which approximates fair value due to its short-term nature. The carrying values of the Company’s prepaid expenses, other current assets, accounts payable and accrued expenses approximate their fair values due to their short-term nature. The following table presents information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values: As of September 30, 2024: Level 1 Level 2 Level 3 Total Assets: Cash equivalents (money market) $ 139,021 $ - $ - $ 139,021 $ 139,021 $ - $ - $ 139,021 As of December 31, 2023: Level 1 Level 2 Level 3 Total Assets: Cash equivalents (money market) $ 102,484 $ - $ - $ 102,484 $ 102,484 $ - $ - $ 102,484

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2024
Property, Plant and Equipment [Abstract]
Property and Equipment	4. Property and Equipment The following is the summary of the Company’s property and equipment and related accumulated depreciation and amortization as of September 30, 2024 and December 31, 2023: Useful Life September 30, 2024 December 31, 2023 Internal use software 3 years $ 309 $ 296 Furniture and fixtures 5 years 386 380 Lab equipment 7 years 823 514 Leasehold improvements 7 years 272 247 Total property and equipment 1,790 1,437 Less: accumulated depreciation and amortization ( 610 ) ( 381 ) Total property and equipment, net $ 1,180 $ 1,056

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2024
Accrued Liabilities and Other Liabilities [Abstract]
Accrued Expenses and Other Current Liabilities	5. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: September 30, 2024 December 31, 2023 Accrued research and development expenses $ 10,863 $ 6,384 Accrued bonus expenses 2,961 2,810 Accrued general and administrative expenses and other professional fees 1,320 1,092 Other current liabilities 554 554 Total accrued expenses and other current liabilities $ 15,698 $ 10,840

Leases

Leases	9 Months Ended
	Sep. 30, 2024
Leases [Abstract]
Leases	6. Leases Operating Lease Right-of-Use Asset In January 2022 , the Company entered into a lease agreement for an office facility and laboratory space in New York, New York that commenced in April 2022 and ends in July 2029 with an additional five-year option to extend the lease beyond July 2029 at the then-prevailing effective market rental rate . Upon commencement of this lease, the Company recorded operating lease right-of-use assets and operating lease liabilities of $ 11.6 million based on the present value of payments over the lease term using an estimated incremental borrowing rate of 8.53 % in accordance with the provisions of ASC Topic 842, Leases (“ASC 842”). In connection with the Company’s lease of office space and laboratory space, the Company provided a security deposit to the landlord in the form of a letter of credit totaling $ 1.2 million. The cash collateralizing the letter of credit was included in long-term restricted cash in the Company’s condensed balance sheets as of September 30, 2024 and December 31, 2023. This lease was classified as an operating lease in accordance with the provisions of ASC 842. The Company did no t recognize any right-of-use assets and lease liabilities associated with the potential option to renew or extend. The Company’s operating lease agreement does not contain any significant residual value guarantees or restrictive covenants. The remaining lease terms and payment terms as of September 30, 2024 and December 31, 2023 were 4.8 years and 5.6 years, respectively. The components of this operating lease were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Operating lease expense $ 537 $ 537 $ 1,611 $ 1,611 Variable lease expense 116 295 344 489 Total operating lease expense $ 653 $ 832 $ 1,955 $ 2,100 Cash paid for amounts included in the measurement of lease liabilities, included in operating cash flows $ 528 $ 720 $ 1,578 $ 1,775 The following table provides a reconciliation of the Company’s remaining undiscounted contractual rent obligations due within each year ended December 31 to the operating lease liabilities recognized as of September 30, 2024: Years ended December 31 Operating 2024 $ 535 2025 2,152 2026 2,206 2027 2,261 2028 2,318 Thereafter 1,372 Total lease payments 10,844 Less: present value adjustment ( 1,945 ) Total operating lease liabilities $ 8,899 Included in the balance sheet: Current portion of lease liabilities - operating 2,108 Non-current portion of lease liabilities - operating 6,791 Total operating lease liabilities $ 8,899 Equipment Finance Leases Commencing in April 2022, the Company leases certain laboratory equipment under financing arrangements accounted for as finance leases in accordance with the provision of ASC 842 that are classified in the Company’s condensed balance sheet as finance lease liabilities with related right-of-use assets recorded and depreciated on a straight-line basis over the estimated useful life of 7 years. The total gross, accumulated amortization, and net book values of equipment finance lease right-of-use assets capitalized under such finance lease arrangements at September 30, 2024 were $ 2.2 million, $ 0.7 million and $ 1.5 million, respectively. Under the terms of the equipment finance lease agreements executed through the issuance of these unaudited condensed financial statements, the principal balances plus interest for the equipment are to be repaid in full after 60 monthly installments following lease commencement, with lease commencement dates ranging from April 1, 2022 to April 1, 2023 , annual imputed interest rates ranging from 7.90 % to 9.30 %, and monthly installment payment amounts ranging from approximately $ 4,000 to $ 18,000 . As of September 30, 2024, the total aggregate monthly installment payment amount was approximately $ 49,000 for equipment finance lease agreements executed through the issuance date of these unaudited condensed financial statements. The weighted-average remaining lease payment term, weighted-average remaining amortization term, and weighted-average effective interest rate for the Company's equipment finance lease agreements as of September 30, 2024 were 2.9 years, 5.1 years, and 8.58 %, respectively. The weighted-average remaining lease payment term, weighted-average remaining amortization term, and weighted-average effective interest rate for the Company's equipment finance lease agreements as of December 31, 2023 were 3.7 years, 5.7 years, and 8.59 %, respectively. The components of the equipment finance leases were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Reduction in the carrying amount of ROU assets, finance $ 80 $ 79 $ 245 $ 227 Interest on finance lease liabilities 36 44 96 136 Total finance lease expense $ 116 $ 123 $ 341 $ 363 Cash paid for amounts included in the measurement of lease liabilities, included in financing cash flows $ 111 $ 107 $ 294 $ 320 The following table provides a reconciliation of the Company’s remaining equipment finance lease obligations due within each year ending December 31 to the equipment finance lease liabilities recognized at September 30, 2024: Years ended December 31 Equipment Finance Leases 2024 $ 147 2025 587 2026 587 2027 359 2028 11 Total lease payments 1,691 Less: imputed interest ( 187 ) Total finance lease liabilities $ 1,504 Included in the balance sheet: Current portion of lease liabilities - finance 574 Non-current portion of lease liabilities - finance 930 Total finance lease liabilities $ 1,504

Convertible SAFE Note

Convertible SAFE Note	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Convertible Safe Note	7. Convertible SAFE Note On August 24, 2023, the Company entered into the convertible SAFE Note with Sarepta Therapeutics, Inc. in a principal amount of $ 4.0 million bearing simple interest at an annual rate of 10 % to be repaid after one year in the absence of the occurrence of certain settlement events. The convertible SAFE Note was accounted for as a liability in accordance with the provisions of ASC Topic 480, Distinguishing Liabilities from Equity , with changes in estimated fair value recognized in earnings. In connection with the convertible SAFE Note, the Company incurred issuance costs of $ 0.1 million that were recorded as a discount to the liability balance and amortized to interest expense over the term of the convertible SAFE Note. During the three months ended September 30, 2023 (inception of the convertible SAFE Note), the estimated fair value of the convertible SAFE Note, gross of unamortized discount, increased by $ 272,000 to $ 4.1 million. Upon the declaration of effectiveness of the Company's IPO registration statement on November 2, 2023, the carrying value of the convertible SAFE Note of $ 4.4 million, net of unamortized discount, automatically converted into 411,815 shares of the Company’s common stock (see Note 8).

Capital Stock

Capital Stock	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Capital Stock	8. Capital Stock As of September 30, 2024 and December 31, 2023, the Company’s amended and restated certificate of incorporation provided that the authorized capital stock of the Company was 510,000,000 shares consisting of 500,000,000 shares of common stock and 10,000,000 shares of undesignated preferred stock, both with a par value of $ 0.0001 per share. As of September 30, 2024 and December 31, 2023, 33,070,045 shares and 26,668,485 shares, respectively, of the Company's common stock authorized were issued, including 11,598 shares and 22,107 shares, respectively, that were legally issued upon the early exercise of unvested stock options and that are excluded from the number of shares outstanding until the right to repurchase subsequently lapses upon vesting. The Company did no t repurchase any shares of common stock during the three months ended September 30, 2024, and repurchased a total of 2,991 shares of common stock issued pursuant to the early exercise of stock options granted under the 2021 Plan for a total of approximately $ 13,000 during the nine months ended September 30, 2024, which was recorded to treasury stock in the Company's condensed balance sheet (see Note 9). Each common share entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, if any, as may be declared by the Company’s Board of Directors. No cash dividends have been declared or paid by the Company. Upon the declaration of effectiveness of the Company’s IPO registration statement on November 2, 2023, the Company's outstanding convertible SAFE Note automatically converted into 411,815 shares of common stock (see Note 7). Upon the closing of the Company's IPO on November 7, 2023, the Company issued and sold 9,090,910 shares of its common stock, and subsequently, the underwriters partially exercised their associated 30-day option to purchase additional shares of common stock with 1,048,746 additional shares issued. The net proceeds to the Company from the IPO and subsequent partial exercise of the underwriters’ 30-day option to purchase additional shares were approximately $ 100.3 million based on the initial offering price of $ 11.00 per share, after deducting underwriting discounts, commissions and offering expenses totaling $ 11.3 million. Also upon the closing of the Company's IPO on November 7, 2023, all 85,495,722 then outstanding shares of the Company’s series A convertible preferred stock and all 58,157,823 then outstanding shares of the Company’s series B convertible preferred stock converted into 8,070,027 shares and 6,386,337 shares of common stock, respectively, including 896,764 shares of common stock issued as a result of series B convertible preferred stock antidilution provisions. On March 11, 2024, the Company entered into a common stock purchase agreement to issue and sell an aggregate of 6,278,905 shares of its common stock at a price of $ 15.13 per share, in a private placement that closed on March 13, 2024 (the "Private Placement"). The gross and net proceeds received from the Private Placement were approximately $ 95.0 million and $ 88.7 million, respectively, after deducting approximately $ 6.3 million of commissions and other offering costs. The Company had reserved the following number of shares of common stock for the exercise of outstanding stock options, settlement of outstanding RSUs, and future issuance of stock-based awards: September 30, 2024 December 31, 2023 Options to purchase shares of common stock under the 2021 Plan and 2023 Plan 3,471,849 2,415,740 RSUs subject to settlement in shares of common stock under the 2023 Plan 272,692 - Shares available for issuance under the 2023 Plan 2,175,005 2,293,816 Shares available for issuance under the 2023 ESPP 505,284 238,600 Total shares of common stock reserved for future issuance 6,424,830 4,948,156

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	9. Stock-based Compensation In February 2021, the Company adopted the 2021 Equity Incentive Plan (the “2021 Plan”) for the issuance of stock options to the Company’s key directors, officers, employees and consultants, as a means to secure the benefits arising from capital stock ownership. In connection with the Company’s IPO in November 2023, the Company adopted the 2023 Equity Incentive Plan (the “2023 Plan”) and the 2023 Employee Stock Purchase Plan (the "2023 ESPP" and collectively with the 2021 Plan and 2023 Plan, the “Plans”). The purposes of the Plans are to promote the alignment of the interests of key directors, officers, employees, and consultants with the success of the Company and to provide compensation opportunities to attract, retain and motivate directors, officers, employees, and consultants of the Company. Upon adoption, the maximum number of shares of common stock that may be issued under the 2023 Plan was initially 4,737,000 shares, which was approximately the sum of (i) 1,803,980 new shares, plus (ii) the 2021 Plan’s available reserve, plus (iii) the number of returning shares, if any, upon the cancellation or forfeiture of equity awards that are outstanding under the 2021 Plan. In addition, the number of shares of common stock reserved for issuance under the 2023 Plan will automatically increase on January 1 of each year, beginning on January 1, 2024, and continuing through and including January 1, 2033, by 5 % of the total number of shares of common stock outstanding on December 31 of the immediately preceding calendar year, or a lesser number of shares determined by the Company’s Board of Directors prior to the applicable January 1. Upon adoption, the maximum number of shares of common stock that may be issued under the 2023 ESPP was initially 238,600 shares. The number of shares of common stock reserved for issuance under the 2023 ESPP will automatically increase on January 1 of each calendar year, beginning on January 1, 2024 and continuing through and including January 1, 2033, by the lesser of (i) 1 % of the total number of shares of capital stock outstanding on December 31 of the preceding calendar year, (ii) 477,200 shares and (iii) a number of shares determined by the Company’s Board of Directors. Shares subject to purchase rights granted under the 2023 ESPP that terminate without having been exercised in full will not reduce the number of shares available for issuance under the 2023 ESPP. On January 1, 2024, the number of shares of common stock reserved for issuance under the 2023 Plan and the 2023 ESPP automatically increased by 1,333,424 shares and 266,684 shares, respectively, to totals of 6,070,424 shares and 505,284 shares, respectively. As of September 30, 2024, 2,175,005 shares and 505,284 shares were available for future issuance under the 2023 Plan and 2023 ESPP, respectively. No shares have been issued under the 2023 ESPP through September 30, 2024. Stock option activity Stock options granted under the 2021 Plan generally (i) are subject to requisite service requirements, (ii) vest over a four-year period with 25 % of the options granted vesting after one year and the remainder vesting in equal monthly installments over the following 36 months , and (iii) allow for early exercise subject to repurchase. Stock options granted under the 2021 Plan to certain of the Company’s non-employees vest in equal monthly installments over a four-year period or vested upon the achievement of a certain milestone event. The Company did no t repurchase any shares of common stock during the three months ended September 30, 2024, and repurchased a total of 2,991 shares of common stock issued pursuant to the early exercise of stock options granted under the 2021 Plan for a total of approximately $ 13,000 during the nine months ended September 30, 2024, which was recorded to treasury stock in the Company's condensed balance sheet (see Note 8). Stock options granted under the 2023 Plan generally (i) are subject to requisite service requirements, and (ii) vest over a four-year period with 25 % of the options granted vesting after one year and the remainder vesting in equal monthly installments over the following 36 months . Stock options granted under the 2023 Plan to certain of the Company's non-employees vest in equal annual installments over a three-year period or over a one-year period. The following table summarizes the stock option activity under the 2021 Plan and the 2023 Plan for the three months ended September 30, 2024 (weighted-average remaining contractual term (in years) is not stated in thousands): Number of Weighted- Weighted- Weighted- Aggregate Shares (per share) (per share) (in years) Value Outstanding as of December 31, 2023 2,415,740 $ 8.32 $ 5.80 7.83 $ 13,689 Granted 1,469,580 15.86 11.78 Exercised ( 125,646 ) 3.72 2.39 1,231 Forfeited ( 222,058 ) 10.69 7.82 Expired ( 65,767 ) 12.87 5.37 Outstanding as of September 30, 2024 3,471,849 $ 11.44 $ 8.33 8.40 $ 5,523 Vested options outstanding and exercisable as of September 30, 2024 1,202,058 $ 6.70 $ 4.61 7.25 $ 4,527 Unvested options outstanding and exercisable as of September 30, 2024 751,693 $ 10.41 $ 7.55 8.22 $ 996 Unvested options outstanding and unexercisable as of September 30, 2024 1,518,098 $ 15.71 $ 11.66 9.41 $ - The weighted-average grant date fair value of stock options granted during the nine months ended September 30, 2023 was $ 13.71 per share. The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The total intrinsic value of stock options exercised during the nine months ended September 30, 2023 was $ 39,000 . The total grant date fair values of stock options vested during the three months ended September 30, 2024 and September 30, 2023 were $ 1.3 million and $ 1.0 million, respectively. The total grant date fair values of stock options vested during the nine months ended September 30, 2024 and September 30, 2023 were $ 2.9 million and $ 1.8 million, respectively. The Company estimated the fair value of options granted using a Black-Scholes option pricing model with the following assumptions presented on a weighted average basis during the nine months ended September 30, 2024 (not stated in thousands): Nine Months Ended September 30, 2024 Weighted average risk-free interest rate 4.14 % Expected term (in years) 6.02 Expected volatility 85.78 % Expected dividend yield 0.00 % The expected dividend yield is 0.00 % as the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. RSU activity RSUs granted under the 2023 Plan generally (i) are subject to requisite service requirements, and (ii) vest over a four-year period with 25 % of the RSUs granted vesting after approximately one year and the remainder vesting in equal quarterly installments over the following 12 quarters . The following table summarizes the RSU activity under the 2023 Plan for the nine months ended September 30, 2024: Number of Weighted- Shares (per share) Unvested as of December 31, 2023 - $ - Granted 284,620 15.58 Vested - - Forfeited ( 11,928 ) 14.85 Unvested as of September 30, 2024 272,692 $ 15.61 Stock-based compensation expense Stock-based compensation expense was classified as follows in the Company’s unaudited condensed statements of operations and comprehensive loss: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Research and development expense $ 1,817 $ 503 $ 4,337 $ 1,219 General and administrative expense 1,973 371 4,630 1,020 Total stock-based compensation expense $ 3,790 $ 874 $ 8,967 $ 2,239 As of September 30, 2024, there was $ 20.8 million of unrecognized stock-based compensation expense related to unvested stock options and RSUs estimated to be recognized over a weighted-average period of 1.37 years.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	10. Net Loss per Share Basic and diluted net loss per common share attributable to common stockholders was calculated as follows: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Numerator: Net loss attributable to common stockholders $ ( 29,489 ) $ ( 20,108 ) $ ( 72,409 ) $ ( 52,207 ) Denominator: Weighted-average common shares outstanding, basic and diluted 33,063,153 1,626,734 31,354,821 1,619,152 Net loss per share attributable to common stockholders, basic and diluted $ ( 0.89 ) $ ( 12.36 ) $ ( 2.31 ) $ ( 32.24 )

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies Leases —As of September 30, 2024, the Company had entered into commitments under lease agreements to rent laboratory and office space and finance equipment (see Note 6). Commitments —As of September 30, 2024, the Company had entered into commitments under license, acquisition, research collaboration and sponsored research agreements with third parties (see Note 12). In addition, the Company has entered into services agreements with third parties for pharmaceutical manufacturing and research activities in the normal course of business, which can generally be terminated by the Company with 30 - to 60 -days’ written notice, unless otherwise indicated. Further, certain of the Company’s manufacturing agreements could require early termination and wind-down payments due from the Company upon either the termination of its clinical trials or if the Company terminates such agreements for convenience. Contingencies —From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business. The Company recognizes any associated legal fees as incurred and accrues a liability for such contingent liability matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. For all periods presented, the Company was not a party to any pending material litigation or other material legal proceedings, except that on October 12, 2023, Rocket Pharmaceuticals, Inc. (“Rocket”) filed a lawsuit in the U.S. District Court for the Southern District of New York against the Company and two individuals claiming, among other things, misappropriation of confidential information and trade secrets. The individual defendants are two former employees of the Company’s analytical development team, both of whom were employed at Rocket before joining the Company in 2021. The complaint alleges the individual defendants downloaded confidential Rocket company documents and other proprietary materials prior to leaving Rocket in 2021 and that the Company used this information to advance its programs. The complaint seeks unspecified damages and asks the court to enjoin the Company from competing and working in the market for gene therapy treatments targeting cardiac diseases. The Company retained legal counsel to assist with its ongoing review of the allegations in Rocket’s complaint and is confident in its defenses to the allegations. In addition, in August 2024, the Company asserted counterclaims against Rocket and Spacecraft Seven LLC, a wholly owned subsidiary of Rocket, for misappropriation of trade secrets, correction of inventorship of certain patents, breach of contract, and tortious interference with contract. The case is currently in the discovery phase. While it is not possible to predict the outcome with certainty and an estimate of the possible loss cannot be made, the Company currently does not expect the final outcome will have a material adverse effect on its timelines for development of its product candidates. Indemnification Agreements —In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its Board of Directors and executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. For all periods presented, the Company has not incurred any material costs as a result of such indemnifications.

License, Acquisition, Research

License, Acquisition, Research and Collaboration and Sponsored Research Agreements	9 Months Ended
	Sep. 30, 2024
Business Combinations [Abstract]
License, Acquisition, Research and Collaboration and Sponsored Research Agreements	12. License, Acquisition, Research and Collaboration and Sponsored Research Agreements Adverum Biotechnologies —On January 25, 2021, the Company entered into an exclusive license agreement with Adverum Biotechnologies Inc. (“Adverum”) to in-license materials and technology related to the treatment of cardiomyopathy due to Friedreich ataxia ("FA") (the “Adverum Agreement”). In connection with the Adverum Agreement, the Company gained access to a portfolio of inventions, patent rights, technology, and licensed methods that the Company continues to develop, and the Company will assume all development and commercialization activities worldwide. Pursuant to the Adverum Agreement, the Company paid a one-time up-front non-refundable fee of $ 7.5 million, and is obligated to pay aggregate development and regulatory milestones of up to $ 17.5 million including a $ 3.5 million development milestone that was achieved and paid in the first quarter of 2023, and aggregate sales event and commercialization milestones of up to $ 49.0 million. The Company is obligated to pay Adverum tiered royalties ranging from high single-digits to sub teens based on annual aggregate worldwide net sales of Products (as defined in the Adverum Agreement). As of September 30, 2024, there were no research and development expenses recorded by the Company or payments made to Adverum under the terms of the Adverum Agreement other than the one-time up-front non-refundable fee of $ 7.5 million and the $ 3.5 million development milestone that was achieved and paid in the first quarter of 2023. The Adverum Agreement remains in effect until termination at the date of the last royalty term to expire. The Company can terminate the Adverum Agreement with 120 days’ written notice. The Adverum Agreement can also be terminated as a result of a patent challenge, material breach of contractual terms, or insolvency by either party. Cornell University —On May 27, 2020, the Company entered into two exclusive license agreements with Cornell University (“Cornell”) (the “First Cornell License Agreement” and the “Second Cornell License Agreement,” collectively the “May 2020 Cornell License Agreements”). The First Cornell License Agreement is for the in-license of technology related to portfolios for APOE-associated Alzheimer’s disease and Anti-Tau, although the Company’s license is not restricted by such indications and it includes assignment to the Company of Cornell’s IND for the use of AAVrh10.hAPOE2 vector to treat APOE4 homozygous patients who are at risk for or have Alzheimer’s disease to support development of the Company’s LX1001 program. The Second Cornell License Agreement is for the in-license of technology related to a portfolio for FA although the Company’s license is not restricted by such indications, and it includes assignment to the Company of Cornell’s IND for the use of AAVrh.10cUhCLN2 to treat children with CLN2 Batten disease to support development of the Company’s LX1004 program. Through the May 2020 Cornell License Agreements, the Company gains access to a portfolio of inventions, patent rights, technology, and licensed methods that the Company continues to develop. Under the terms of the May 2020 Cornell License Agreements, the Company has assumed all development and commercialization activities worldwide with respect to the licensed technology. As initial consideration for the May 2020 Cornell License Agreements, the Company paid Cornell an upfront payment in cash of $ 0.3 million and issued $ 1.3 million of notes (“Notes”). In November 2020, Notes with outstanding principal of $ 1.3 million were cancelled in exchange for 1,337,610 shares of series A convertible preferred stock, which converted into 126,258 shares of common stock upon the closing of the Company's IPO on November 7, 2023. As additional consideration, the Company is required to pay Cornell up to $ 8.4 million upon the achievement of specific clinical and regulatory milestones under the First Cornell License Agreement and up to $ 4.3 million in two portfolios and up to $ 0.6 million for a third portfolio upon the achievement of specific clinical and regulatory milestones under the Second Cornell License Agreement. In the second quarter of 2022, a clinical and regulatory milestone of $ 0.1 million was recognized and paid to Cornell in connection with the Second Cornell License Agreement. The Company is also required to pay Cornell a flat royalty in the mid-single-digits based on net sales of the products covered by the licenses, subject to certain adjustments. Upon expiration of the royalty term of a given licensed product in a country, the respective license becomes non-exclusive and royalty-free. In addition, each of the May 2020 Cornell License Agreements may be terminated by the Company for any reason upon ninety ( 90 ) days’ advance notice to Cornell and by Cornell upon the Company’s material uncured breach, and all licenses and rights granted by either party under such agreement will concurrently terminate. On April 21, 2024, the Company entered into the Third License Agreement (the “Third Cornell License Agreement,” together with the May 2020 Cornell License Agreements, the “Cornell License Agreements”) with Cornell. Pursuant to the Third Cornell License Agreement, Cornell has granted the Company an exclusive license to practice under certain patent rights generated in animal studies conducted by Cornell on behalf of the Company and a non-exclusive license to know-how concerning a gene therapy for FA cardiomyopathy and current and future data generated in an ongoing investigator-initiated Phase 1A trial of AAVrh.10hFXN to treat FA cardiomyopathy. Both licenses are worldwide and cover products with human and non-human prophylactic and therapeutic uses. Cornell has also granted the Company a right of reference to Cornell’s Investigation New Drug application for a gene therapy for FA cardiomyopathy. Under the Third Cornell License Agreement, the Company paid a license issue fee and an initial data transfer fee to Cornell totaling $ 0.6 million. Additionally, the Company will be paying an annual data transfer fee of $ 50,000 until data is no longer being gathered. The Company has agreed to pay annual license maintenance fees ranging from $ 2,500 to $ 25,000 until such time the Company commercializes a licensed product. In addition, the Company will pay Cornell up to an aggregate of $ 2.1 million in regulatory milestones and up to an aggregate of $ 100 million in commercial milestones, plus low single digit royalties on net sales. The Third Cornell License Agreement contains other customary license terms including terms related to sublicensing, development, commercialization, milestones, royalties, intellectual property, and termination. Upon expiration of the applicable royalty term for a product in a given country, the Company shall retain a non-exclusive, royalty free license to the data and know-how, including to continue selling such product in that country. Cornell may terminate the Third Cornell License Agreement if the Company (i) breaches the Third Cornell License Agreement (subject to a cure period), (ii) participates in any proceeding challenging the validity of the licensed patents, (iii) publishes the licensed data without Cornell’s prior written consent, or (iv) does not reach certain milestones. Cornell may also terminate the Third Cornell License Agreement in part on product-by-product basis if the Company does not diligently develop and sale a product. The Company may terminate the Third Cornell License Agreement, in whole or in part with respect to the right of reference, or the licensed data, know-how, or patent rights, with 90 days’ prior written notice to Cornell. During the three and nine months ended September 30, 2023, the Company incurred and paid $ 5,000 and $ 10,000 , respectively in connection with the Cornell License Agreements. During the three and nine months ended September 30, 2024, the Company incurred and paid $ 0 and $ 0.7 million, respectively in connection with the Cornell License Agreements. Stelios Therapeutics, Inc. —Stelios Therapeutics, Inc. (“Stelios”) was an early-stage company developing novel adeno-associated AAV-based gene therapies for rare cardiac conditions including arrhythmogenic cardiomyopathy and TNNI3-associated hypertrophic cardiomyopathy. On July 16, 2021 , the Company acquired 100 % of the outstanding stock of Stelios that was accounted for as an asset acquisition pursuant FASB ASC 805, Business Combinations . The Company is required to pay up to a remaining aggregate of $ 12.5 million to the selling shareholders of Stelios upon the achievement of certain development milestones, excluding a $ 6.0 million development milestone that was achieved in the third quarter of 2024 and paid in the fourth quarter of 2024. Dr. Eric Adler, the Company's Chief Medical Officer and Head of Research, was a co-founder of Stelios and a selling shareholder. Of the $ 6.0 million development milestone payment, Dr. Adler received approximately $ 1.3 million. Regents of the University of California, San Diego —Stelios entered into exclusive worldwide license agreements on April 23, 2020, and August 6, 2020 (the “First UCSD Agreement” and the “Second UCSD Agreement”, respectively) with the Regents of UCSD to in-license materials and intellectual property related to gene therapies for arrhythmogenic right ventricular cardiomyopathy and hypertrophic cardiomyopathy, respectively. The First UCSD Agreement and the Second UCSD Agreement relate to the Company’s development efforts for its LX2021 and LX2022 programs, respectively. In connection with the First UCSD Agreement and the Second UCSD Agreement, the Company gained access to inventions, patent rights, technology, and licensed methods that it continues to develop, and it has assumed all worldwide development and commercialization activities with respect to the licensed technologies. The First UCSD Agreement and Second UCSD Agreement required Stelios to pay one-time up-front non-refundable cash fees of $ 20,000 for each agreement and requires the Company to pay aggregate development and commercialization milestones of up to $ 4.8 million and $ 2.4 million, respectively, and low- to mid-single digit royalties and low-single digit royalties, respectively, based on aggregate net sales. The only research and development expenses incurred by Stelios or the Company and payments made to the Regents of UCSD through September 30, 2024 under the terms of the First UCSD Agreement and the Second UCSD Agreement were the one-time up-front non-refundable cash fees of $ 20,000 for each agreement. The Company has the right to terminate the First UCSD Agreement and the Second UCSD Agreement at any time upon sixty ( 60 )-days’ written notice to the Regents of UCSD. On October 4, 2021, the Company entered into an exclusive worldwide license agreement (the “Third UCSD Agreement” and collectively with the First UCSD Agreement and the Second UCSD Agreement, the “UCSD Agreements”) with the Regents of UCSD to in-license materials and intellectual property related to LX2020, a gene therapy for arrhythmogenic right ventricular cardiomyopathy. The Third UCSD Agreement relates to the Company’s development efforts for its LX2020 program. In connection with the Third UCSD Agreement, the Company gained access to inventions, patent rights, technology, and licensed methods that it continues to develop, and it has assumed all worldwide development and commercialization activities with respect to the licensed technology. The Third UCSD Agreement required the Company to pay a one-time up-front non-refundable cash fee of $ 20,000 and requires the Company to pay aggregate development and commercialization milestones of up to $ 4.0 million, and low- to mid-single digit royalties based on aggregate net sales. Research and development expenses incurred by the Company and payments made to the Regents of UCSD under the terms of the Third UCSD Agreement were the one-time up-front non-refundable cash fee of $ 20,000 as well as a $ 0.1 million development milestone that was achieved during the third quarter of 2024. The Company has the right to terminate the Third UCSD Agreement at any time upon sixty ( 60 )-days’ written notice to the Regents of UCSD. On December 3, 2021, the Company entered into two sponsored research agreements with the Regents of UCSD (the "First UCSD SRA", the "Second UCSD SRA", and collectively, the “UCSD SRAs”) for the Company’s LX2020, LX2021 and LX2022 programs in connection with the UCSD Agreements. Under the terms of the UCSD SRAs, the Company has the first rights to obtain non-exclusive or exclusive, sublicensable, royalty-bearing, perpetual and transferable worldwide licenses in any resulting inventions owned by the Regents of UCSD or resulting inventions jointly owned between the Company and the Regents of UCSD, and the Company retains the rights to any resulting inventions owned by the Company. The UCSD SRAs each have a two-year term and may be terminated early by the Company at any time upon the giving of thirty ( 30 ) days’ written notice to the Regents of UCSD. The total costs to be invoiced to the Company over the terms of the UCSD SRAs are $ 5.6 million, of which the Company incurred $ 0.2 million and $ 1.3 million of research and development expenses during the three and nine months ended September 30, 2023, respectively. The Company paid $ 0 and $ 0.2 million to the Regents of UCSD in connection with the UCSD SRAs during the three and nine months ended September 30, 2023, respectively. The Company did no t incur any research and development expenses in connection with the UCSD SRAs during the three and nine months ended September 30, 2024. The Company paid $ 0 and $ 0.7 million to the Regents of UCSD in connection with the UCSD SRAs during the three and nine months ended September 30, 2024, respectively. The Company has paid a cumulative total of $ 4.0 million to the Regents of UCSD as of September 30, 2024, in connection with the UCSD SRAs. On April 13, 2024, the Company entered into a third sponsored research agreement with the Regents of UCSD (the “Third UCSD SRA”) for the Company’s LX2022 program in connection with the Second UCSD Agreement. Under the terms of the Third UCSD SRA, the Company has the first rights to obtain non-exclusive or exclusive, sublicensable, royalty-bearing, perpetual and transferable worldwide licenses in any resulting inventions owned by the Regents of UCSD or resulting inventions jointly owned between the Company and the Regents of UCSD, and the Company retains the rights to any resulting inventions owned by the Company. The Third UCSD SRA has a two-year term and may be terminated early by the Company at any time upon the giving of thirty ( 30 ) days’ written notice to the Regents of UCSD. The costs to be invoiced to the Company over the term of the Third UCSD SRA are $ 0.7 million, and the Company may incur additional costs of $ 0.6 million under the Third UCSD SRA if certain study objectives are met. The Company also entered into an amendment to the Second UCSD SRA for the Company’s LX2022 program that extended the term of the Second UCSD SRA to December 2024. The Company incurred $ 0.1 million and $ 0.5 million of research and development costs during the three and nine months ended September 30, 2024, respectively, and paid $ 0.3 million and $ 0.6 million during the three and nine months ended September 30, 2024, respectively, to the Regents of UCSD in connection with the Third UCSD SRA. On April 19, 2024, the Company entered into an amendment to the First UCSD SRA (as amended, the "Amended First UCSD SRA") for the Company’s LX2021 program in connection with the First UCSD Agreement. The Amended First UCSD SRA extends the term of the First UCSD SRA to December 2026 and provides for additional research and development studies and expenses. The total costs to be invoiced to the Company under the Amended First UCSD SRA are $ 0.8 million. The Company incurred $ 0.1 million and $ 0.5 million of research and development costs during the three and nine months ended September 30, 2024, respectively, and paid $ 0.3 million during each of the three and nine months ended September 30, 2024 to the Regents of UCSD in connection with the Amended First UCSD SRA. Weill Cornell Medical College —On February 2, 2021, the Company entered into a Research Collaboration Agreement with Weill Cornell Medical College (“WCM” and the “WCM Agreement”) in connection with the Cornell License Agreements entered on May 27, 2020. The Company committed to fund scientific research at WCM to investigate further and potentially enhance the technology licensed to the Company pursuant to the License Agreements. Under the terms of the WCM Agreement, each WCM invention, joint invention, and related joint results for which an Improvement, as defined in the WCM Agreement, applies and the Company has made an election to amend the Cornell License Agreements, the Company has the first option to negotiate in good faith with WCM for royalty- bearing, worldwide license, under Cornell patent rights, Cornell rights, and Cornell’s interest in joint patent rights, to develop, make, have made, use, offer for sale, sell, have sold, and import derived products in the field. During the three and nine months ended September 30, 2023 the Company incurred $ 0.1 million and $ 1.0 million, respectively, of research and development costs and paid $ 0 and $ 1.8 million, respectively, to Cornell in connection with the WCM Agreement. During each of the three and nine months ended September 30, 2024 the Company incurred and paid $ 0.3 million of research and development costs to Cornell in connection with the WCM Agreement. The WCM Agreement expired in accordance with its terms in February 2024.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events Subsequent events have been evaluated through November 13, 2024, which is the date that these unaudited condensed financial statements were issued and were available to be issued.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates —The preparation of the financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to the accruals of research and development costs, including accruals of research contract costs, and assumptions used to estimate the fair value of the Company’s stock option awards and, prior to its IPO, to determine the fair value of its common stock. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when facts and circumstances dictate. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates.
Net Loss per Share	Net Loss per Share— The Company follows the two-class method when computing net income (loss) per common share as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (loss) per common share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company considers its convertible preferred stock to be participating securities as, in the event a dividend is paid on common stock, the holders of these securities would be entitled to receive dividends on a basis consistent with the common stockholders. The Company also considers the shares issued upon the early exercise of stock options that are subject to repurchase to be participating securities because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. There is no allocation required under the two-class method during periods of loss since the participating securities do not have a contractual obligation to share in the losses of the Company. Basic net income (loss) per common share is computed by dividing the net income (loss) per common share by the weighted-average number of common shares outstanding for the period. Diluted net income (loss) per common share is computed by adjusting net income (loss) to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per common share is computed by dividing the diluted net loss by the weighted-average number of common shares outstanding for the period, including potential dilutive common shares. For the purposes of this calculation, shares of convertible preferred stock are considered potential dilutive common shares. In periods in which the Company reported a net loss, diluted net loss per common share was the same as basic net loss per common share since dilutive common shares were not assumed to have been issued if their effect was anti-dilutive. During (i) the three and nine months ended September 30, 2023, 8,070,027 potential common shares related to the conversion of series A convertible preferred stock and 5,489,573 potential common shares related to the conversion of series B convertible preferred stock, which converted into 8,070,027 common shares and 6,386,337 common shares, respectively, in connection with the Company’s IPO on November 7, 2023 (see Note 8), and 2,322,843 potential common shares related to the exercise of outstanding stock options, and (ii) the three and nine months ended September 30, 2024, 3,744,541 total potential common shares related to the exercise of outstanding stock options and settlement of outstanding restricted stock units ("RSUs") (see Note 9), were excluded from the computation of diluted net loss per common share because including them would have had an anti-dilutive effect as the Company reported net losses for those periods.
Concentrations of Credit Risk	Concentrations of Credit Risk —Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and restricted cash. The Company’s cash and restricted cash balances exceed Federal Deposit Insurance Corporation insurance limits, and the Company’s cash equivalents consist of investments in a U.S. government money market fund. The Company’s cash and cash equivalents and restricted cash is held with large financial institutions that management believes to be of high credit quality. To date, the Company has no t recognized any losses caused by uninsured balances.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values: As of September 30, 2024: Level 1 Level 2 Level 3 Total Assets: Cash equivalents (money market) $ 139,021 $ - $ - $ 139,021 $ 139,021 $ - $ - $ 139,021 As of December 31, 2023: Level 1 Level 2 Level 3 Total Assets: Cash equivalents (money market) $ 102,484 $ - $ - $ 102,484 $ 102,484 $ - $ - $ 102,484

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2024
Leases [Abstract]
Components of Operating Lease	The components of this operating lease were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Operating lease expense $ 537 $ 537 $ 1,611 $ 1,611 Variable lease expense 116 295 344 489 Total operating lease expense $ 653 $ 832 $ 1,955 $ 2,100 Cash paid for amounts included in the measurement of lease liabilities, included in operating cash flows $ 528 $ 720 $ 1,578 $ 1,775
Reconciliation of Remaining Undiscounted Contractual Rent Obligations	The following table provides a reconciliation of the Company’s remaining undiscounted contractual rent obligations due within each year ended December 31 to the operating lease liabilities recognized as of September 30, 2024: Years ended December 31 Operating 2024 $ 535 2025 2,152 2026 2,206 2027 2,261 2028 2,318 Thereafter 1,372 Total lease payments 10,844 Less: present value adjustment ( 1,945 ) Total operating lease liabilities $ 8,899 Included in the balance sheet: Current portion of lease liabilities - operating 2,108 Non-current portion of lease liabilities - operating 6,791 Total operating lease liabilities $ 8,899
Components of Equipment Finance Leases	The components of the equipment finance leases were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Reduction in the carrying amount of ROU assets, finance $ 80 $ 79 $ 245 $ 227 Interest on finance lease liabilities 36 44 96 136 Total finance lease expense $ 116 $ 123 $ 341 $ 363 Cash paid for amounts included in the measurement of lease liabilities, included in financing cash flows $ 111 $ 107 $ 294 $ 320
Reconciliation of Remaining Equipment Finance Lease Obligations	The following table provides a reconciliation of the Company’s remaining equipment finance lease obligations due within each year ending December 31 to the equipment finance lease liabilities recognized at September 30, 2024: Years ended December 31 Equipment Finance Leases 2024 $ 147 2025 587 2026 587 2027 359 2028 11 Total lease payments 1,691 Less: imputed interest ( 187 ) Total finance lease liabilities $ 1,504 Included in the balance sheet: Current portion of lease liabilities - finance 574 Non-current portion of lease liabilities - finance 930 Total finance lease liabilities $ 1,504

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2024
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	The following is the summary of the Company’s property and equipment and related accumulated depreciation and amortization as of September 30, 2024 and December 31, 2023: Useful Life September 30, 2024 December 31, 2023 Internal use software 3 years $ 309 $ 296 Furniture and fixtures 5 years 386 380 Lab equipment 7 years 823 514 Leasehold improvements 7 years 272 247 Total property and equipment 1,790 1,437 Less: accumulated depreciation and amortization ( 610 ) ( 381 ) Total property and equipment, net $ 1,180 $ 1,056

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2024
Accrued Liabilities and Other Liabilities [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: September 30, 2024 December 31, 2023 Accrued research and development expenses $ 10,863 $ 6,384 Accrued bonus expenses 2,961 2,810 Accrued general and administrative expenses and other professional fees 1,320 1,092 Other current liabilities 554 554 Total accrued expenses and other current liabilities $ 15,698 $ 10,840

Capital Stock (Tables)

Capital Stock (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuances	The Company had reserved the following number of shares of common stock for the exercise of outstanding stock options, settlement of outstanding RSUs, and future issuance of stock-based awards: September 30, 2024 December 31, 2023 Options to purchase shares of common stock under the 2021 Plan and 2023 Plan 3,471,849 2,415,740 RSUs subject to settlement in shares of common stock under the 2023 Plan 272,692 - Shares available for issuance under the 2023 Plan 2,175,005 2,293,816 Shares available for issuance under the 2023 ESPP 505,284 238,600 Total shares of common stock reserved for future issuance 6,424,830 4,948,156

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Summary of Stock Option Activity	The following table summarizes the stock option activity under the 2021 Plan and the 2023 Plan for the three months ended September 30, 2024 (weighted-average remaining contractual term (in years) is not stated in thousands): Number of Weighted- Weighted- Weighted- Aggregate Shares (per share) (per share) (in years) Value Outstanding as of December 31, 2023 2,415,740 $ 8.32 $ 5.80 7.83 $ 13,689 Granted 1,469,580 15.86 11.78 Exercised ( 125,646 ) 3.72 2.39 1,231 Forfeited ( 222,058 ) 10.69 7.82 Expired ( 65,767 ) 12.87 5.37 Outstanding as of September 30, 2024 3,471,849 $ 11.44 $ 8.33 8.40 $ 5,523 Vested options outstanding and exercisable as of September 30, 2024 1,202,058 $ 6.70 $ 4.61 7.25 $ 4,527 Unvested options outstanding and exercisable as of September 30, 2024 751,693 $ 10.41 $ 7.55 8.22 $ 996 Unvested options outstanding and unexercisable as of September 30, 2024 1,518,098 $ 15.71 $ 11.66 9.41 $ -
Summary of Following Assumptions Presented on Weighted Average Basis	The Company estimated the fair value of options granted using a Black-Scholes option pricing model with the following assumptions presented on a weighted average basis during the nine months ended September 30, 2024 (not stated in thousands): Nine Months Ended September 30, 2024 Weighted average risk-free interest rate 4.14 % Expected term (in years) 6.02 Expected volatility 85.78 % Expected dividend yield 0.00 %
Summary of RSU activity	The following table summarizes the RSU activity under the 2023 Plan for the nine months ended September 30, 2024: Number of Weighted- Shares (per share) Unvested as of December 31, 2023 - $ - Granted 284,620 15.58 Vested - - Forfeited ( 11,928 ) 14.85 Unvested as of September 30, 2024 272,692 $ 15.61
Summary of Stock-Based Compensation Expenses	Stock-based compensation expense was classified as follows in the Company’s unaudited condensed statements of operations and comprehensive loss: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Research and development expense $ 1,817 $ 503 $ 4,337 $ 1,219 General and administrative expense 1,973 371 4,630 1,020 Total stock-based compensation expense $ 3,790 $ 874 $ 8,967 $ 2,239

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Schedule of Net Loss Per Share Attributable to Common Stockholders	Basic and diluted net loss per common share attributable to common stockholders was calculated as follows: Three Months Ended Nine Months Ended September 30, September 30, 2024 2023 2024 2023 Numerator: Net loss attributable to common stockholders $ ( 29,489 ) $ ( 20,108 ) $ ( 72,409 ) $ ( 52,207 ) Denominator: Weighted-average common shares outstanding, basic and diluted 33,063,153 1,626,734 31,354,821 1,619,152 Net loss per share attributable to common stockholders, basic and diluted $ ( 0.89 ) $ ( 12.36 ) $ ( 2.31 ) $ ( 32.24 )

Description of Business and B_2

Description of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

24 Months Ended

Nov. 07, 2023

Oct. 13, 2023

Aug. 31, 2023

Sep. 30, 2024

Jun. 30, 2024

Mar. 31, 2024

Sep. 30, 2023

Jun. 30, 2023

Mar. 31, 2023

Sep. 30, 2024

Sep. 30, 2023

Dec. 31, 2023

Dec. 31, 2021

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Reverse stock split

10.594230-for-1

Net Loss

$ 29,489

$ 21,238

$ 21,682

$ 20,108

$ 13,441

$ 18,658

$ 72,409

$ 52,207

$ 66,400

Cash and cash equivalents, including restricted cash

157,020

157,020

121,466

Accumulated deficit

$ (254,249)

(254,249)

$ (181,840)

Proceeds from issuance of common stock

$ 100,300

Series A and Series B Convertible Preferred Stock [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Aggregate total net proceeds raised with issuance of convertible preferred stock

$ 185,000

SAFE [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Net proceeds

$ 3,900

IPO [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Net proceeds

$ 100,300

Private Placement Offering [Member]

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Net proceeds

$ 88,700

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)			3 Months Ended		9 Months Ended		85 Months Ended
	Nov. 07, 2023	Nov. 02, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Mar. 31, 2024
Summary of Significant Accounting Policies [Line Items]
Loss recognized from uninsured balances							$ 0
SAFE | Common Stock | IPO
Summary of Significant Accounting Policies [Line Items]
Number of common shares on conversion of debt instrument		411,815
Exercise of Outstanding Stock Options
Summary of Significant Accounting Policies [Line Items]
Antidilutive securities excluded from Computation of diluted net loss per common share				2,322,843		2,322,843
Exercise of Outstanding Stock Options | Restricted Stock Units [Member]
Summary of Significant Accounting Policies [Line Items]
Antidilutive securities excluded from Computation of diluted net loss per common share			3,744,541		3,744,541
Series A Convertible Preferred Stock
Summary of Significant Accounting Policies [Line Items]
Antidilutive securities excluded from Computation of diluted net loss per common share				8,070,027		8,070,027
Number of shares issued during the period upon conversion of convertible securities	8,070,027
Series A Convertible Preferred Stock | Common Stock
Summary of Significant Accounting Policies [Line Items]
Number of shares issued during the period upon conversion of convertible securities	8,070,027
Series B Convertible Preferred Stock
Summary of Significant Accounting Policies [Line Items]
Antidilutive securities excluded from Computation of diluted net loss per common share				5,489,573		5,489,573
Series B Convertible Preferred Stock | Common Stock
Summary of Significant Accounting Policies [Line Items]
Number of shares issued during the period upon conversion of convertible securities	6,386,337

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 139,021	$ 102,484
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	139,021	102,484
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	139,021	102,484
Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 139,021	$ 102,484

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 1,790	$ 1,437
Less: accumulated depreciation and amortization	(610)	(381)
Total property and equipment, net	1,180	1,056
Internal Use Software
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 309	296
Useful Life	3 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 386	380
Useful Life	5 years
Lab Equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 823	514
Useful Life	7 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 272	$ 247
Useful Life	7 years

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accrued Liabilities and Other Liabilities [Abstract]
Accrued research and development expenses	$ 10,863	$ 6,384
Accrued bonus expenses	2,961	2,810
Accrued general and administrative expenses and other professional fees	1,320	1,092
Other current liabilities	554	554
Total accrued expenses and other current liabilities	$ 15,698	$ 10,840

Leases - Additional Information

Leases - Additional Information (Details)			1 Months Ended			9 Months Ended	12 Months Ended	60 Months Ended
	Apr. 01, 2023	Apr. 01, 2022 USD ($)	Jul. 31, 2029	Apr. 30, 2022	Jan. 31, 2022	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jul. 31, 2034	Aug. 01, 2029 USD ($)	Dec. 11, 2023 USD ($) Installment
Lessee, Lease, Description [Line Items]
Operating lease commencement date				2022-04
Operating lease right-of-use assets						$ 8,435,000	$ 9,442,000
Operating lease liabilities						8,899,000
Net book values						$ 1,540,000	$ 1,763,000
Remaining lease terms						4 years 9 months 18 days	4 years 9 months 18 days
Remaining lease payment terms						5 years 7 months 6 days	5 years 7 months 6 days
Weighted average remaining lease payment term						2 years 10 months 24 days	3 years 8 months 12 days
Weighted average remaining amortization term						5 years 1 month 6 days	5 years 8 months 12 days
Weighted average effective interest rate						8.58%	8.59%
Office Facility and Laboratory Space
Lessee, Lease, Description [Line Items]
Operating lease agreement entered date					2022-01
Operating lease end date			2029-07
Option to extend						additional five-year option to extend the lease beyond July 2029 at the then-prevailing effective market rental rate
Existence of option to extend								true
Operating lease right-of-use assets		$ 11,600,000
Operating lease liabilities		$ 11,600,000
Incremental borrowing rate		8.53%
Office Facility and Laboratory Space | Scenario Forecast
Lessee, Lease, Description [Line Items]
Renewal term									5 years
Operating lease right-of-use assets									$ 0
Operating lease liabilities									$ 0
Office Facility and Laboratory Space | Letter of Credit
Lessee, Lease, Description [Line Items]
Security deposit		$ 1,200,000
Laboratory Equipment
Lessee, Lease, Description [Line Items]
Estimated useful life						7 years
Total gross						$ 2,200,000
Accumulated amortization						700,000
Net book values						1,500,000
Number of monthly installments | Installment										60
Finance lease, commencement date range, start		Apr. 01, 2022
Finance lease, commencement date range, end	Apr. 01, 2023
Total aggregate monthly installment payment amount						$ 49,000
Laboratory Equipment | Minimum
Lessee, Lease, Description [Line Items]
Imputed interest rate										7.90%
Monthly installment payment amounts										$ 4,000
Laboratory Equipment | Maximum
Lessee, Lease, Description [Line Items]
Imputed interest rate										9.30%
Monthly installment payment amounts										$ 18,000

Leases - Components of Operatin

Leases - Components of Operating Lease (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Leases [Abstract]
Operating lease expense	$ 537	$ 537	$ 1,611	$ 1,611
Variable lease expense	116	295	344	489
Total operating lease expense	653	832	1,955	2,100
Cash paid for amounts included in the measurement of lease liabilities, included in operating cash flows	$ 528	$ 720	$ 1,578	$ 1,775

Leases - Reconciliation of Rema

Leases - Reconciliation of Remaining Undiscounted Contractual Rent Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Leases [Abstract]
2024	$ 535
2025	2,152
2026	2,206
2027	2,261
2028	2,318
Thereafter	1,372
Total lease payments	10,844
Less: present value adjustment	(1,945)
Total operating lease liabilities	8,899
Included in the balance sheet:
Current portion of lease liabilities - operating	2,108	$ 2,087
Non-current portion of lease liabilities - operating	$ 6,791	$ 7,786

Leases - Components of Equipmen

Leases - Components of Equipment Finance Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Leases [Abstract]
Reduction in the carrying amount of ROU assets, finance	$ 80	$ 79	$ 245	$ 227
Interest on finance lease liabilities	36	44	96	136
Total finance lease expense	116	123	341	363
Cash paid for amounts included in the measurement of lease liabilities, included in financing cash flows	$ 111	$ 107	$ 294	$ 320

Leases - Reconciliation of Re_2

Leases - Reconciliation of Remaining Equipment Finance Lease Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Leases [Abstract]
2024	$ 147
2025	587
2026	587
2027	359
2028	11
Total lease payments	1,691
Less: imputed interest	(187)
Total finance lease liabilities	1,504
Included in the balance sheet:
Current portion of lease liabilities - finance	574	$ 518
Non-current portion of lease liabilities - finance	$ 930	$ 1,247

Convertible SAFE Note - Additio

Convertible SAFE Note - Additional Information (Details) - SAFE - USD ($)		3 Months Ended
	Nov. 02, 2023	Sep. 30, 2023	Aug. 24, 2023
Debt Instrument [Line Items]
Issuance costs			$ 100,000
Unamortized discount	$ 4,400,000
Total liabilities		$ 4,100,000
Increase in fair value of safe instrument		$ 272,000
Sarepta Therapeutics, Inc
Debt Instrument [Line Items]
Convertible safe note, principal amount			$ 4,000,000
Annual interest rate			10%
IPO | Common Stock
Debt Instrument [Line Items]
Number of common shares on conversion of debt instrument	411,815

Capital Stock - Additional Info

Capital Stock - Additional Information (Details) - USD ($)				3 Months Ended			9 Months Ended
	Mar. 11, 2024	Nov. 07, 2023	Nov. 02, 2023	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Authorized capital stock				510,000,000			510,000,000	510,000,000
Common stock shares authorized				500,000,000			500,000,000	500,000,000
Preferred stock shares authorized				10,000,000			10,000,000	10,000,000
Common stock, par value per share				$ 0.0001			$ 0.0001	$ 0.0001
Preferred stock, par value per share				$ 0.0001			$ 0.0001	$ 0.0001
Common stock, shares issued				33,070,045			33,070,045	26,668,485
Common stock shares issued upon early exercise of unvested stock options				11,598			11,598	22,107
Dividends, common stock, cash							$ 0
Shares repurchased value					$ 13,000
Proceeds from issuance of common stock		$ 100,300,000
Gross proceeds from private placement							88,712,000
2021 Plan
Class of Stock [Line Items]
Repurchase of shares				0
Shares repurchased value							$ 13,000
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares outstanding		85,495,722
Number of shares issued during the period upon conversion of convertible securities		8,070,027
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares outstanding		58,157,823
Series B Convertible Preferred Stock | Antidilutive Securities
Class of Stock [Line Items]
Number of shares issued during the period upon conversion of convertible securities		896,764
Common Stock
Class of Stock [Line Items]
Repurchase of shares					2,991
Number of common shares issued and sold						6,278,905
Common Stock | 2021 Plan
Class of Stock [Line Items]
Repurchase of shares				0			2,991
Shares repurchased value							$ 13,000
Common Stock | Series A Convertible Preferred Stock
Class of Stock [Line Items]
Number of shares issued during the period upon conversion of convertible securities		8,070,027
Common Stock | Series B Convertible Preferred Stock
Class of Stock [Line Items]
Number of shares issued during the period upon conversion of convertible securities		6,386,337
IPO | Common Stock
Class of Stock [Line Items]
Number of common shares issued and sold		9,090,910
Offering price per share		$ 11
Underwriting discounts, commissions and other offering expenses		$ 11,300,000
IPO | SAFE | Common Stock
Class of Stock [Line Items]
Number of common shares on conversion of debt instrument			411,815
Over-Allotment Option | Common Stock
Class of Stock [Line Items]
Number of common shares issued and sold		1,048,746
Private Placement
Class of Stock [Line Items]
Underwriting discounts, commissions and other offering expenses	$ 6,300,000
Gross proceeds from private placement	95,000,000
Net proceeds from private placement	$ 88,700,000
Private Placement | Common Stock
Class of Stock [Line Items]
Number of common shares issued and sold	6,278,905
Offering price per share	$ 15.13

Capital Stock - Schedule of Com

Capital Stock - Schedule of Common Stock Reserved for Future Issuances (Details) - shares	Sep. 30, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	6,424,830	4,948,156
2023 Plan
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	2,175,005	2,293,816
2023 ESPP
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	505,284	238,600
Restricted Stock Units [Member] | 2023 Plan
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	272,692
Common Stock | 2021 Plan and 2023 Plan
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	3,471,849	2,415,740

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)		3 Months Ended			9 Months Ended		11 Months Ended	33 Months Ended	44 Months Ended
	Nov. 07, 2023	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Nov. 07, 2023	Sep. 30, 2024	Jan. 01, 2024	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares reserved for issuance		6,424,830			6,424,830		6,424,830		6,424,830		4,948,156
Stock-based compensation expense					$ 8,967,000	$ 2,239,000
Unrecognized stock-based compensation expense		$ 20,800,000			$ 20,800,000		$ 20,800,000		$ 20,800,000
Unrecognized compensation expense, weighted-average period of recognition					1 year 4 months 13 days
Shares repurchased value			$ 13,000
Common Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Repurchase of shares			2,991
Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted-average grant date fair value of stock options granted						$ 13.71
Intrinsic value of stock options exercised						$ 39,000
Total grant date fair values of options vested		$ 1,300,000		$ 1,000,000	$ 2,900,000	$ 1,800,000
Expected dividend yields percentage					0%
2021 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Repurchase of shares		0
Shares repurchased value					$ 13,000
2021 Plan | Common Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Repurchase of shares		0			2,991
Shares repurchased value					$ 13,000
2021 Plan | Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period									4 years
Vesting period, percentage									25%
2021 Plan | Employee Stock Option | Non-employee
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation payment description								vest over a four-year period with 25% of the options granted vesting after one year and the remainder vesting in equal monthly installments over the following 36 months
2023 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares authorized	4,737,000							4,737,000
Common stock, shares reserved for issuance	1,803,980	2,175,005			2,175,005		2,175,005	1,803,980	2,175,005	6,070,424
Percentage of automatically increase in available shares of common stock on beginning of each calendar year	5%
Increase in aggregate number of shares of common stock reserved for issuance										1,333,424
2023 Plan | Restricted Stock Units [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period							4 years
Vesting period, percentage							25%
Number of shares, granted					284,620
Share based compensation payment description							vest over a four-year period with 25% of the RSUs granted vesting after approximately one year and the remainder vesting in equal quarterly installments over the following 12 quarters
2023 Plan | Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period							4 years
Vesting period, percentage							25%
Share based compensation payment description							vest over a four-year period with 25% of the options granted vesting after one year and the remainder vesting in equal monthly installments over the following 36 months
2023 Plan | Employee Stock Option | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period							3 years
2023 Plan | Employee Stock Option | Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period							1 year
2023 ESPP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares authorized	238,600							238,600
Common stock, shares reserved for issuance		505,284			505,284		505,284		505,284	505,284
Number of shares automatically increase in available shares of common stock under plan	477,200
Increase in aggregate number of shares of common stock reserved for issuance										266,684
Number of shares available for future grants		0			0		0		0
2023 ESPP | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Percentage of automatically increase in available shares of common stock on beginning of each calendar year	1%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - Employee Stock Option [Member] - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average grant date fair value, granted		$ 13.71
Aggregate intrinsic value, exercised		$ 39,000
2021 Plan and 2023 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares outstanding, beginning	2,415,740
Granted, shares	1,469,580
Exercised, shares	(125,646)
Forfeited, shares	(222,058)
Expired, shares	(65,767)
Number of shares outstanding, ending	3,471,849		2,415,740
Number of shares, vested and exercisable	1,202,058
Number of shares, unvested and exercisable	751,693
Number of shares, unvested and unexercisable	1,518,098
Weighted average exercise price, beginning balance	$ 8.32
Weighted average exercise price, granted	15.86
Weighted average exercise price, exercised	3.72
Weighted average exercise price, forfeited	10.69
Weighted average exercise price, Expired	12.87
Weighted average exercise price, ending balance	11.44		$ 8.32
Weighted average exercise price, vested and exercisable	6.7
Weighted average exercise price, unvested and exercisable	10.41
Weighted average exercise price, unvested and unexercisable	15.71
Weighted average grant date fair value, beginning	5.80
Weighted average grant date fair value, granted	11.78
Weighted average grant date fair value, exercised	2.39
Weighted average grant date fair value, forfeited	7.82
Weighted average grant date fair value, expired	5.37
Weighted average grant date fair value, ending	8.33		$ 5.80
Weighted average grant date fair value, vested and exercisable	4.61
Weighted average grant date fair value, Unvested and exercisable	7.55
Weighted average grant date fair value, Unvested and unexercisable	$ 11.66
Weighted average remaining contractual term	8 years 4 months 24 days		7 years 9 months 29 days
Weighted average remaining contractual term, vested and exercisable	7 years 3 months
Weighted average remaining contractual term, unvested and exercisable	8 years 2 months 19 days
Weighted average remaining contractual term, unvested and unexercisable	9 years 4 months 28 days
Aggregate intrinsic value, beginning	$ 13,689,000
Aggregate intrinsic value, exercised	1,231,000
Aggregate intrinsic value, ending	5,523,000		$ 13,689,000
Aggregate intrinsic value, vested and exercisable	4,527,000
Aggregate intrinsic value, unvested and exercisable	$ 996,000

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Following Assumptions Presented on Weighted Average Basis (Details) - Employee Stock Option	9 Months Ended
	Sep. 30, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average risk-free interest rate	4.14%
Expected term (in years)	6 years 7 days
Expected volatility	85.78%
Expected dividend yield	0%

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of RSU activity (Details) - Restricted Stock Units [Member] - 2023 Plan	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares, granted | shares	284,620
Number of shares, forfeited | shares	(11,928)
Number of shares unvested, ending balance | shares	272,692
Weighted average grant date fair value, granted | $ / shares	$ 15.58
Weighted average grant date fair value, unvested, forfeited | $ / shares	14.85
Weighted-average grant date fair value, unvested, ending balance | $ / shares	$ 15.61

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Stock-based Compensation Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 3,790	$ 874	$ 8,967	$ 2,239
Research and development expense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	1,817	503	4,337	1,219
General and administrative expense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 1,973	$ 371	$ 4,630	$ 1,020

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Numerator:
Net Income (Loss)	$ (29,489)	$ (21,238)	$ (21,682)	$ (20,108)	$ (13,441)	$ (18,658)	$ (72,409)	$ (52,207)	$ (66,400)
Denominator:
Weighted-average common shares outstanding, basic	33,063,153			1,626,734			31,354,821	1,619,152
Weighted-average common shares outstanding, diluted	33,063,153			1,626,734			31,354,821	1,619,152
Net loss per share attributable to common stockholders, basic	$ (0.89)			$ (12.36)			$ (2.31)	$ (32.24)
Net loss per share attributable to common stockholders, diluted	$ (0.89)			$ (12.36)			$ (2.31)	$ (32.24)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2024 Employees
Loss Contingencies [Line Items]
Number of former employees	2
Third Parties for Pharmaceutical Manufacturing and Research Activities | Maximum
Loss Contingencies [Line Items]
Termination notice period (in days)	60 days
Third Parties for Pharmaceutical Manufacturing and Research Activities | Minimum
Loss Contingencies [Line Items]
Termination notice period (in days)	30 days

License, Acquisition, Researc_2

License, Acquisition, Research and Collaboration and Sponsored Research Agreements - Additional Information (Details)

1 Months Ended

3 Months Ended

9 Months Ended

34 Months Ended

Apr. 21, 2024 USD ($)

Apr. 19, 2024 USD ($)

Apr. 13, 2024 USD ($)

Dec. 03, 2021 USD ($) IntegerItem

Oct. 04, 2021 USD ($)

Jul. 16, 2021 USD ($)

Jan. 25, 2021 USD ($)

Aug. 06, 2020 USD ($)

May 27, 2020 USD ($) IntegerItem

Apr. 23, 2020 USD ($)

Nov. 30, 2020 USD ($) shares

Sep. 30, 2024 USD ($)

Sep. 30, 2023 USD ($)

Mar. 31, 2023 USD ($)

Sep. 30, 2022 USD ($)

Jun. 30, 2022 USD ($)

Sep. 30, 2024 USD ($)

Sep. 30, 2023 USD ($)

Sep. 30, 2024 USD ($)

Nov. 07, 2023 shares

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Research and development expenses

$ 23,423,000

$ 17,246,000

$ 55,725,000

$ 44,920,000

Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Development milestone paid

6,000,000

Asset acquisition date of acquisition

Jul. 16, 2021

Asset acquisition percentage of outstanding stock acquisition

100%

Payment to selling shareholders

$ 6,000,000

Milestone received

1,300,000

1,300,000

$ 1,300,000

Maximum | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Payment to selling shareholders

$ 12,500,000

Adverum License Agreement | Adverum Biotechnologies Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

One-time up-front non-refundable fee paid

$ 7,500,000

$ 7,500,000

Development milestone paid

$ 3,500,000

Royalty payments description

The Company is obligated to pay Adverum tiered royalties ranging from high single-digits to sub teens based on annual aggregate worldwide net sales of Products (as defined in the Adverum Agreement).

Research and development expenses

$ 0

License agreement termination notice period

120 days

Adverum License Agreement | Adverum Biotechnologies Inc | Maximum

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Development and regulatory milestones due

$ 17,500,000

Commercialization milestones due

$ 49,000,000

Cornell License Agreements | Cornell University

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

License agreement termination notice period

90 days

Number of license agreements | IntegerItem

2

Upfront payment in cash

$ 300,000

Notes issued

1,300,000

Notes with outstanding principal exchanged

$ 1,300,000

Cornell License Agreements | Cornell University | Common Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Converted shares into common stock | shares

126,258

Cornell License Agreements | Cornell University | Series A Convertible Preferred Stock

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Shares issued on debt exchanged | shares

1,337,610

First Cornell License Agreements | Cornell University | Maximum

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Specific clinical and regulatory milestones due

8,400,000

Second Cornell License Agreements | Cornell University

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Clinical and regulatory milestone paid

$ 100,000

Second Cornell License Agreements | Cornell University | Maximum | Two Portfolios

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Specific clinical and regulatory milestones due

4,300,000

Second Cornell License Agreements | Cornell University | Maximum | Third Portfolio

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Specific clinical and regulatory milestones due

$ 600,000

Third Cornell License Agreements | Cornell University

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Research and development expenses

0

5,000

700,000

10,000

License agreement termination notice period

90 days

License fee and initial data transfer fee

$ 600,000

Annual data transfer fee

50,000

Third Cornell License Agreements | Cornell University | Minimum

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Annual license maintenance fees

2,500

Third Cornell License Agreements | Cornell University | Maximum

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Commercialization milestones due

100,000,000

Annual license maintenance fees

25,000

Regulatory milestone to be paid

$ 2,100,000

First UCSD License Agreement | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

One-time up-front non-refundable fee paid

$ 20,000

$ 20,000

License agreement termination notice period

60 days

First UCSD License Agreement | Stelios Therapeutics Inc | Research and Development Expense

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

One-time up-front non-refundable fees

$ 20,000

First UCSD License Agreement | Maximum | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Development and commercialization milestones due

$ 4,800,000

Second UCSD License Agreement | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

License agreement termination notice period

60 days

Second UCSD License Agreement | Stelios Therapeutics Inc | Research and Development Expense

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

One-time up-front non-refundable fees

$ 20,000

Second UCSD License Agreement | Maximum | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Development and commercialization milestones due

$ 2,400,000

Third UCSD License Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Additional costs incurred for research

$ 600,000

Research and development expenses

100,000

500,000

Research agreement term

2 years

Research agreement termination notice period

30 days

Costs incurred for research

$ 700,000

Payment to research and development

300,000

$ 600,000

Third UCSD License Agreement | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

One-time up-front non-refundable fee paid

$ 20,000

License agreement termination notice period

60 days

Development and commercialization milestones description

the Company to pay aggregate development and commercialization milestones of up to $4.0 million, and low- to mid-single digit royalties based on aggregate net sales.

Third UCSD License Agreement | Stelios Therapeutics Inc | Research and Development Expense

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Development milestone paid

100,000

One-time up-front non-refundable fees

$ 20,000

Third UCSD License Agreement | Maximum | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Development and commercialization milestones due

$ 4,000,000

Amended First UCSD Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Research and development expenses

100,000

$ 500,000

Costs incurred for research

$ 800,000

Payment to research and development

300,000

300,000

UCSD Sponsored Research Agreements | Stelios Therapeutics Inc

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Research and development expenses

0

200,000

0

1,300,000

Number of research agreements | IntegerItem

2

Research agreement term

2 years

Research agreement termination notice period

30 days

Costs incurred for research

$ 5,600,000

Payment to research and development

0

0

700,000

200,000

$ 4,000,000

Research Collaboration Agreement | Weill Cornell Medical College

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Research and development expenses

100,000

1,000,000

Payment to research and development

$ 300,000

$ 0

$ 300,000

$ 1,800,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	9 Months Ended
	Mar. 11, 2024	Mar. 31, 2024	Sep. 30, 2024
Subsequent Event [Line Items]
Gross proceeds from private placement			$ 88,712
Common Stock
Subsequent Event [Line Items]
Number of common shares issued and sold		6,278,905
Private Placement
Subsequent Event [Line Items]
Gross proceeds from private placement	$ 95,000
Private Placement | Common Stock
Subsequent Event [Line Items]
Number of common shares issued and sold	6,278,905
Offering price per share	$ 15.13