0000950170-24-129274 | 10-Q | XBRL Viewer

Common Stock

9 Months Ended

Sep. 30, 2024

Common Stock, Number of Shares, Par Value and Other Disclosure [Abstract]

Note 7. Common Stock

As of September 30, 2024, the Company was authorized to issue 260,590,689 shares of common stock, par value $0.001 per share. As of December 31, 2023, the Company was authorized to issue 260,590,689 shares of common stock, par value $0.001 per share.

In September 2024, the Company amended the 2021 Stock Option and Grant Plan, as amended (“2021 Plan”) to, among other things, increase the shares reserved for issuance under the 2021 Plan to 5,403,314 shares.

On October 28, 2024, the Company amended and restated its certificate of incorporation, which was filed immediately prior to the closing of its IPO and among other things, increased the number of shares of common stock authorized for issuance to 500.0 million shares of common stock.

In October 2024, the Company completed its IPO of its common stock. In connection with the Company's IPO, the Company issued and sold 18.4 million shares of its common stock, which included an additional 2.4 million shares of common stock that were issued to the underwriters pursuant to the full exercise of their option to purchase additional shares of common stock, at the public offering price of $18.00 per share. As a result, the Company received approximately $302.6 million in net proceeds, after deducting underwriting discounts and commissions and other offering costs payable by the Company of approximately $28.6 million.

The Company reserved the following shares of common stock, on an as-converted basis, for future issuance:


	As of September 30,		As of December 31,
	2024		2023
Series A Convertible Preferred Stock		8,710,490		8,710,490
Series B Convertible Preferred Stock		14,129,284		14,129,284
Restricted stock outstanding under 2021 Plan		508,433		774,225
Restricted stock outstanding outside of 2021 Plan		170,803		227,819
Options issued and outstanding under 2021 Plan		3,018,073		1,123,296
Shares reserved for future grants under 2021 Plan		906,277		1,634,488
		27,443,360		26,599,602

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Payments for Operating Leases

As of September 30, 2024, future minimum rental payments for operating leases, including for the Original Leased Space, were as follows (in thousands):


As of September 30,	Future Payments
2024 (remaining three months)	$	437
2025		4,469
2026		4,612
2027		4,760
2028		4,912
Thereafter		18,921
Total lease payments		38,111
Less: imputed interest		(12,885	)
Total present value of operating lease liability	$	25,226

Operating lease liability, current	$	1,116
Operating lease liability, non-current		24,110
Total operating lease liability	$	25,226

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
Condensed Statements of Cash Flows - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net loss	$ (51,130)	$ (30,714)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,013	605
Non-cash operating lease expense	890	515
Stock-based compensation	1,888	1,045
Amortization of premiums (discounts), net	(601)
Deferred income tax	(338)
Other	52	5
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,249)	(34)
Accounts receivable	(60)	(33)
Other non-current assets	(173)	(215)
Accounts payable	2,419	(1,131)
Accrued expenses and other current liabilities	579	559
Operating lease, net	198	(528)
Net cash used in operating activities	(46,512)	(29,926)
Cash flows from investing activities:
Purchase of property and equipment	(1,491)	(1,639)
Proceeds from sale of non-financial asset	22,625	25,000
Purchases of available-for-sale marketable securities	(65,828)
Maturities of available-for-sale marketable securities	17,335
Net cash (used in) provided by investing activities	(27,359)	23,361
Cash flows from financing activities:
Proceeds from issuance of Series B Convertible Preferred Stock, net of issuance costs	74,942	74,521
Repurchases of unvested restricted common stock	(1)	(1)
Proceeds from exercise of stock options	16
Payments of deferred offering costs	(1,327)
Net cash provided by financing activities	73,630	74,520
Net (decrease) increase in cash, cash equivalents and restricted cash	(241)	67,955
Cash, cash equivalents and restricted cash, beginning of period	89,388	31,469
Cash, cash equivalents and restricted cash, end of period	89,147	99,424
Cash and cash equivalents	88,242	98,519
Restricted Cash	905	905
Total cash, cash equivalents and restricted cash at end of period	89,147	99,424
Supplemental cash flow information:
Cash paid for income taxes	232
Supplemental disclosure for noncash investing and financing activities:
Right-of-use asset obtained in exchange for operating lease liability	(12,462)
Unpaid deferred offering costs included in accounts payable and accrued expenses and other current liabilities	1,882
Property and equipment included in accounts payable and accrued expenses and other current liabilities	$ 321	$ 355

Balance Sheet Components (Tables)

9 Months Ended

Sep. 30, 2024

Balance Sheet Related Disclosures [Abstract]

Summary of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):


	As of September 30,		As of December 31,
	2024		2023
Prepaid expenses	$	1,152	$	874
Prepaid clinical trial costs		679		—
Prepaid bonus		241		378
Prepaid taxes		232		75
Interest receivable		123		—
Other current assets		241		92
Prepaid expenses and other current assets	$	2,668	$	1,419

Summary of Property and Equipment, Net

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


	As of September 30,			As of December 31,
	2024			2023
Lab equipment	$	5,613		$	4,967
Furniture, fixtures, and office equipment		1,222			713
Leasehold improvements		717			389
Computer equipment		401			218
Total property and equipment		7,953			6,287
Less: Accumulated depreciation and amortization		(2,541	)		(1,622	)
Property and equipment, net	$	5,412		$	4,665

Summary of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following (in thousands):


	As of September 30,		As of December 31,
	2024		2023
Accrued compensation expense	$	2,109	$	2,954
Accrued general and administrative expense		1,845		209
Accrued research and development expense		1,699		829
Accrued income taxes payable		200		200
Other current liabilities		134		85
Accrued expenses and other current liabilities	$	5,987	$	4,277

Available-for-Sale Marketable Securities and Fair Value Measurements - Schedule of Fair Value Measurements on Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities, current	$ 42,291
Marketable securities, non-current	6,979
Total measured at fair value	132,671	$ 86,574
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total measured at fair value	60,991	86,574
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total measured at fair value	71,680
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,689
Marketable securities, current	21,722
U.S. Treasury Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,689
Marketable securities, current	21,722
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	694
Marketable securities, current	9,741
Marketable securities, non-current	6,022
U.S. Government Agency Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	694
Marketable securities, current	9,741
Marketable securities, non-current	6,022
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities, current	990
Marketable securities, non-current	957
Corporate Debt Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities, current	990
Marketable securities, non-current	957
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	60,991	86,574
Money Market Funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	60,991	$ 86,574
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20,027
Marketable securities, current	9,838
Commercial Paper \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20,027
Marketable securities, current	$ 9,838

Net Loss Per Share

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Net Loss Per Share

Note 10. Net Loss Per Share

For all periods presented, diluted net loss per share is the same as basic net loss per share since the effect of including potential common shares is anti-dilutive. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive were as follows (in common stock equivalent shares):


	As of September 30,		As of September 30,
	2024		2023
Outstanding stock options		2,380,470		131,812
Unvested restricted stock subject to repurchase		605,879		1,039,033
Total antidilutive securities		2,986,349		1,170,845

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			2 Months Ended	3 Months Ended			9 Months Ended
	May 31, 2024	Jul. 31, 2023	Jun. 30, 2023	Jul. 31, 2023	Jun. 30, 2024	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Oct. 31, 2024	Dec. 31, 2023
Temporary Equity [Line Items]
Proceeds from issuance of Series B Convertible Preferred Stock, net of issuance costs								$ 74,942	$ 74,521
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Issuance of convertible preferred stock, shares					60,828,732	2,027,622	58,801,098
Conversion price per share								$ 1.23297			$ 1.23297
Series B Convertible Preferred Stock \| Tranche One
Temporary Equity [Line Items]
Issuance of convertible preferred stock, shares		2,000,000	58,800,000
Conversion price per share		$ 1.23297		$ 1.23297
Proceeds from issuance of Series B Convertible Preferred Stock, net of issuance costs				$ 74,500
Series B Convertible Preferred Stock \| Tranche Two
Temporary Equity [Line Items]
Issuance of convertible preferred stock, shares	60,800,000
Proceeds from issuance of Series B Convertible Preferred Stock, net of issuance costs	$ 74,900
Subsequent Event \| Initial Public Offering (IPO)
Temporary Equity [Line Items]
Outstanding convertible preferred stock conversion in to common stock										22,839,774
Converted preferred stock outstanding										196,657,452
Conversion price per share										$ 8.6103

Convertible Preferred Stock

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Convertible Preferred Stock

Note 6. Convertible Preferred Stock

Immediately prior to the closing of the Company's IPO in October 2024, the Company’s outstanding convertible preferred stock automatically converted into 22,839,774 shares of common stock. Converted preferred stock outstanding as of the date of the IPO consisted of 196,657,452 shares. Each share of outstanding convertible preferred stock was converted into 8.6103 shares of common stock.

As of September 30, 2024, the Company's convertible preferred stock consisted of the following (in thousands, except for share and per share amounts):


Series	Authorized Shares		Issued and Outstanding		Carrying Value		Liquidation Preference		Conversion Price Per Share
Series A		75,000,000		75,000,000	$	74,694	$	75,000	$	1.00000
Series B		121,657,452		121,657,452		149,463		150,000		1.23297

As of December 31, 2023, the Company's convertible preferred stock consisted of the following (in thousands, except for share and per share amounts):


Series	Authorized Shares		Issued and Outstanding		Carrying Value		Liquidation Preference		Conversion Price Per Share
Series A		75,000,000		75,000,000	$	74,694	$	75,000	$	1.00000
Series B		121,657,452		60,828,720		74,521		75,000		1.23297

In June 2023 and July 2023, the Company issued 58.8 million and 2.0 million, respectively, shares of Series B Convertible Preferred Stock at an issuance price of $1.23297 per share for total net proceeds of $74.5 million under the first tranche.

In May 2024, the Company executed the second tranche of the Series B Convertible Preferred Stock financing arrangement and issued the remaining 60.8 million shares of Series B Convertible Preferred Stock for net proceeds of $74.9 million.

Balance Sheet Components - Summary 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	$ 7,953	$ 6,287
Less: Accumulated depreciation and amortization	(2,541)	(1,622)
Property and equipment, net	5,412	4,665
Lab equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	5,613	4,967
Furniture, fixtures, and office equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	1,222	713
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	717	389
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 401	$ 218

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Summary of Potentially Dilutive Securities Not Included in Calculation of Diluted Loss Per Share


	As of September 30,		As of September 30,
	2024		2023
Outstanding stock options		2,380,470		131,812
Unvested restricted stock subject to repurchase		605,879		1,039,033
Total antidilutive securities		2,986,349		1,170,845

Organization and Basis of Presentation

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Basis of Presentation

Note 1. Organization and Basis of Presentation

Description of the Business

Septerna, Inc. (“Septerna” or the “Company”) is a clinical-stage biotechnology company pioneering a new era of G protein-coupled receptor (“GPCR”) oral small molecule drug discovery powered by its proprietary Native Complex PlatformTM. The Company's industrial-scale platform aims to unlock the full potential of GPCR therapies and has led to the discovery and development of its deep pipeline of product candidates focused on treating patients in three therapeutic areas: endocrinology, immunology and inflammation, and metabolic diseases.

The Company was incorporated in Delaware in December 2019, under the name GPCR NewCo, Inc. In June 2021, the Company changed its name to Septerna, Inc. The Company is headquartered in South San Francisco, California.

Reverse Stock Split

On October 18, 2024, the Company effected a 1-for-8.6103 reverse stock split of its issued and outstanding shares of common stock. Upon the effectiveness of the reverse stock split, (i) all shares of outstanding common stock were adjusted; (ii) the conversion ratio of the convertible preferred stock was adjusted; (iii) the number of shares of common stock for which each outstanding option to purchase common stock is exercisable were adjusted; and (iv) the exercise price of each outstanding option to purchase common stock was adjusted. All of the outstanding common stock (including shares of common stock subject to the Company’s options and as converted for the outstanding convertible preferred stock), share prices, exercise prices and per share amounts contained in the condensed financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. The number of authorized shares did not change.

Initial Public Offering

In October 2024, the Company completed its initial public offering (“IPO”), pursuant to which it issued and sold an aggregate of 18.4 million shares of its common stock at the IPO price of $18.00 per share, including 2.4 million shares that were issued to the underwriters pursuant to the full exercise of their option to purchase additional shares, resulting in net proceeds of approximately $302.6 million, after deducting underwriting discounts, commissions and other offering expenses payable by the Company of approximately $28.6 million. Immediately prior to the closing of the IPO, the Company’s outstanding convertible preferred stock automatically converted into 22,839,774 shares of common stock.

Following the closing of the IPO, no shares of convertible preferred stock were authorized or outstanding. In connection with the completion of the IPO, on October 28, 2024, the Company’s certificate of incorporation was amended and restated to (i) authorize 500.0 million shares of common stock, par value $0.001 per share, which eliminates all references to the previously existing series of convertible preferred stock; and (ii) authorize 10.0 million shares of undesignated preferred stock, par value $0.001 per share, that may be issued from time to time by the Company’s board of directors in one or more series.

The Company’s unaudited condensed financial statements as of September 30, 2024, including share and per share amounts, do not give effect to the IPO and related actions as it closed subsequent to September 30, 2024.

Liquidity and Capital Resources

The accompanying unaudited condensed financial statements have been prepared assuming the Company will continue as a going concern, which assumes that the Company will realize its assets and satisfies its liabilities in the normal course of business. The Company is subject to risks inherent in operating an early-stage biotechnology business. These risks include, but are not limited to, dependence on the development of marketable products, the ability to attract, retain, and motivate qualified personnel, rapid technological changes and the rapidly evolving nature of the biotechnology industry.

The Company has incurred significant losses and negative cash flows from operations since its inception and expects to incur losses as a result of its continued research and development activities. To date, none of the Company’s product candidates have been approved by the U.S. Food and Drug Administration (the “FDA”) for commercial sale and, therefore, the Company has not generated any revenue from product sales.

The Company historically financed its operations primarily through the issuances of convertible promissory notes and convertible preferred stock, and most recently, through sale of its common stock in an IPO.

The Company will need additional financing to support its continuing operations and pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, it expects to finance its operations through equity offerings, debt financings or other capital sources, including collaborations with other companies or other strategic transactions. The Company may not be able to obtain funding on acceptable terms, or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders.

For the nine months ended September 30, 2024 and 2023, the Company incurred net losses of $51.1 million and $30.7 million, respectively. The Company had an accumulated deficit of $97.7 million as of September 30, 2024. The Company expects to continue to generate operating losses for the foreseeable future. The Company believes its cash, cash equivalents, marketable securities, and marketable securities, non-current of $137.5 million as of September 30, 2024, together with the net proceeds of approximately $302.6 million from its IPO, will be sufficient to fund its operations for, at least, 12 months from the date of issuance of the unaudited condensed financial statements.

Basis of Presentation

The accompanying unaudited interim condensed financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act of 1933, as amended (the “Securities Act”), and reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for the fair presentation of the Company’s unaudited interim condensed financial statements as of September 30, 2024 and December 31, 2023, and for the three and nine months ended September 30, 2024 and 2023. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Updates (“ASUs”), of the Financial Accounting Standards Board (“FASB”). The interim condensed financial statements are unaudited. The operating results presented in these unaudited interim condensed financial statements are not necessarily indicative of the results that may be expected for the full year or for any other future annual or interim period. Actual results could differ materially from estimates and assumptions. As appropriate, the Company assesses estimates each period and updates them to reflect current information, and generally reflect any changes in estimates in the period first identified.

These unaudited interim condensed financial statements should be read in conjunction with the Company's audited financial statements for the year ended December 31, 2023 and notes thereto, included in the Company’s final IPO prospectus filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) under the Securities Act on October 25, 2024.

Significant Accounting Policies

During the nine months ended September 30, 2024, there were no changes to the Company’s significant accounting policies as described in Note 2 of the audited financial statements for the year ended December 31, 2023 as referenced above, other than the policies outlined below.

Cash Equivalents and Marketable Securities

The Company holds marketable securities that consist of highly liquid, investment grade debt securities. The Company's cash and marketable securities are held or issued by financial institutions that management believes are of high credit quality. Marketable securities are classified and accounted for as available-for-sale. Available-for-sale marketable securities with original maturities of 90 days or less are classified as cash equivalents. Available-for-sale marketable securities with original maturities over 90 days and remaining maturities of less than 12 months are classified as current. Available-for-sale marketable securities with remaining maturities of more than 12 months for which the Company has the intent and ability to hold the security for more than 12 months are classified as non-current. The Company’s marketable securities are carried at estimated fair value, which is derived from independent pricing sources based on quoted prices in active markets for similar securities. Unrealized gains and losses are reported in stockholders’ deficit as accumulated other comprehensive income (loss). The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in interest income on the condensed statements of operations and comprehensive loss.

The Company has the ability, if necessary, to liquidate any of its cash equivalents and available-for-sale marketable securities to meet its liquidity needs in the next 12 months. After consideration of the Company’s objectives to preserve capital, as well as its liquidity requirements, it may sell these available-for-sale marketable securities prior to their stated maturities.

The Company reviews its portfolio of available-for-sale marketable securities, using both quantitative and qualitative factors, to determine if declines in fair value below amortized cost have resulted from a credit-related loss or other factors. If the decline in fair

value is due to credit-related factors, the Company recognizes a loss in its condensed statement of operations, whereas if the decline in fair value is not due to credit-related factors, the Company recognizes the loss in other comprehensive loss.

The Company excludes the applicable accrued interest from both the fair value and amortized cost basis of available-for-sale marketable securities for purposes of identifying and measuring an impairment. Accrued interest receivable on available-for-sale marketable securities is recorded within prepaid expenses and other current assets on the interim condensed balance sheets. The Company’s accounting policy is to not measure an allowance for credit loss for accrued interest receivable and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which is considered to be in the period in which it is determined the accrued interest will not be collected.

Deferred Offering Costs

The Company’s deferred offering costs consist of legal, accounting and other general and administrative costs directly attributable to the Company’s IPO. As of September 30, 2024, $3.2 million of deferred offering costs were included within other non-current assets in the Company’s condensed balance sheet. As of December 31, 2023, there were no deferred offering costs. Upon the consummation of the Company's IPO in October 2024, these costs will be reclassified to additional paid-in capital in stockholders' equity in the Company's condensed balance sheets.

Accounting Pronouncements Not Yet Adopted

From time to time, new accounting pronouncements are issued by the FASB, under its Accounting Standards Codification (“ASC”) or other standard setting bodies, and adopted by the Company as of the specified date.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. ASU 2023-07 will improve reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses on an interim and annual basis. The ASU is effective for fiscal years beginning after December 15, 2023, and interim periods after December 5, 2024, with early adoption permitted. The Company is currently evaluating the impact of ASU 2023-07 on its financial statements and related disclosures.

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the transparency and decision usefulness of income tax disclosures. The standard is intended to improve income tax disclosures primarily related to the rate reconciliation and income taxes paid information. This update also includes certain other amendments to improve the effectiveness of income tax disclosures. The ASU is effective for fiscal years beginning after December 15, 2024, on a prospective basis with early adoption and retrospective reporting permitted. The Company is currently evaluating the impact of ASU 2023-09 on its financial statements and related disclosures.

Stock-Based Compensation - Schedule of Restricted Stock Award Activity (Details) - Restricted Stock [Member]	9 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance \| shares	227,819
Restricted stock awards vested \| shares	(57,016)
Number of Shares Outstanding, Ending Balance \| shares	170,803
Weighted-Average Grant Date Fair Value Per Share, Beginning Balance \| $ / shares	$ 3.79
Restricted stock awards vested, Weighted Average Fair Value \| $ / shares	3.77
Weighted-Average Grant Date Fair Value Per Share, Ending Balance \| $ / shares	$ 3.75
2021 Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance \| shares	774,225
Restricted stock awards vested \| shares	(251,493)
Restricted stock awards repurchased \| $	$ (14,299)
Number of Shares Outstanding, Ending Balance \| shares	508,433
Weighted-Average Grant Date Fair Value Per Share, Beginning Balance \| $ / shares	$ 2.32
Restricted stock awards vested, Weighted Average Fair Value \| $ / shares	$ 2.54
Restricted stock awards repurchased ,Weighted Average Fair Value \| $	$ 2.31
Weighted-Average Grant Date Fair Value Per Share, Ending Balance \| $ / shares	$ 2.27

- Definition

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

+ References

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

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-Publisher FASB
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+ Details

Available-for-Sale Marketable Securities and Fair Value Measurements - Additional Information (Details)	Sep. 30, 2024 USD ($) Position	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-Sale [Line Items]
Interest receivable	$ 123,000
Number of available-for-sale marketable securities in unrealized loss positions less than 12 months \| Position	13
Prepaid Expenses and Other Current Assets
Debt Securities, Available-for-Sale [Line Items]
Interest receivable	$ 100,000	$ 0

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
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-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

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-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

+ Details

Common Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	9 Months Ended
	Oct. 31, 2024	Sep. 30, 2024	Oct. 28, 2024	Dec. 31, 2023
Over-Allotment Option \| Subsequent Event
Common Stock [Line Items]
Sale of common stock	2,400,000
Initial Public Offering (IPO) \| Subsequent Event
Common Stock [Line Items]
Common stock, shares authorized			500,000,000
Common stock, par value			$ 0.001
Sale of common stock	18,400,000
Public offering price per share	$ 18
Net proceeds from initial public offering	$ 302.6
Underwriting discounts commissions and other offering costs	$ 28.6
Common Stock [Member]
Common Stock [Line Items]
Common stock, shares authorized		260,590,689		260,590,689
Common stock, par value		$ 0.001		$ 0.001
Common Stock [Member] \| 2021 Plan [Member]
Common Stock [Line Items]
Increase in shares reserved for future issuance, in shares		5,403,314

Organization and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended						9 Months Ended
	Oct. 18, 2024	Oct. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Oct. 28, 2024	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net loss			$ (20,523)	$ (16,510)	$ (14,097)	$ (10,945)	$ (10,598)	$ (9,171)	$ (51,130)	$ (30,714)
Accumulated deficit			(97,706)						(97,706)			$ (46,576)
Cash, cash equivalents, marketable securities current and non-current			137,500						137,500
Subsequent Event
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Reverse Stock Split description	1-for-8.6103
Subsequent Event \| Initial Public Offering (IPO)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of common stock		18,400,000
Public offering price per share		$ 18
Net proceeds from initial public offering		$ 302,600
Underwriting discounts commissions and other offering costs		$ 28,600
Converted convertible preferred stock outstanding		22,839,774
Common stock, shares authorized											500,000,000
Common stock, par value											$ 0.001
Undesignated preferred stock authorized											10,000,000
Undesignated common stock, par value											$ 0.001
Subsequent Event \| Over-Allotment Option
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of common stock		2,400,000
Other Noncurrent Assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred offering costs			$ 3,200						$ 3,200

Available-for-Sale Marketable Securities and Fair Value Measurements

9 Months Ended

Sep. 30, 2024

Available-for-Sale Marketable Securities and Fair Value Measurements [Abstract]

Available-for-Sale Marketable Securities and Fair Value Measurements

Note 4. Available-for-Sale Marketable Securities and Fair Value Measurements

The Company records marketable securities and cash equivalents at their estimated fair values, which are based on market prices from a variety of industry standard data providers and generally represent quoted prices for similar assets in active markets or have been derived from observable market data.

Fair value is determined based on a three-tier hierarchy under the authoritative guidance for fair value measurements and disclosures that prioritizes the inputs used in measuring fair value as follows:

Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

Level 2: Quoted prices in markets that are not active or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; and

Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurements and unobservable (i.e., supported by little or no market activity).

The fair value measurements of the Company’s cash equivalents and marketable securities are identified at the following levels within the fair value hierarchy (in thousands):


	September 30, 2024
			Fair Value Measurement
	Total		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	60,991	$	60,991	$	—	$	—
Commercial paper		20,027		—		20,027		—
U.S. treasury securities		1,689		—		1,689		—
U.S. government agency securities		694		—		694		—
Marketable securities, current:
U.S. treasury securities		21,722		—		21,722		—
U.S. government agency securities		9,741		—		9,741		—
Commercial paper		9,838		—		9,838		—
Corporate debt securities		990		—		990		—
Marketable securities, non-current:
U.S. government agency securities		6,022		—		6,022		—
Corporate debt securities		957		—		957		—
Total measured at fair value	$	132,671	$	60,991	$	71,680	$	—


	December 31, 2023
			Fair Value Measurement
	Total		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	86,574	$	86,574	$	—	$	—
Total measured at fair value	$	86,574	$	86,574	$	—	$	—

Available-for-Sale Marketable Securities

As of September 30, 2024, the Company’s available-for-sale marketable securities consist of debt securities, including U.S. Treasury and agency securities, corporate debt securities and commercial paper. These available-for-sale marketable securities are carried at fair value and are included in the tables above. The Company records an allowance for credit losses when unrealized losses are due to credit-related factors. At each reporting date, the Company evaluates securities with unrealized losses to determine whether such losses, if any, are due to credit-related factors. The Company evaluates, among others, whether the Company has the intention to sell any of these available-for-sale marketable securities and whether it is not more likely than not that the Company will be required to sell any of them before recovery of the amortized cost basis. Neither of these criteria were met at September 30, 2024. The credit ratings of the securities held remain of the highest quality. Moreover, the Company continues to receive payments of interest and principal as they become due, and the Company's expectation is that those payments will continue to be received timely. Based on this evaluation, as of September 30, 2024, the Company determined that unrealized losses of its available-for-sale marketable securities were primarily attributable to changes in interest rates and non-credit related factors. As such, no allowances for credit losses were recorded at September 30, 2024. The Company did not hold available-for-sale marketable securities at December 31, 2023.

Interest receivable as of September 30, 2024 was $0.1 million and is recorded as a component of prepaid expenses and other current assets on the Company’s condensed balance sheet. The Company did not have interest receivable at December 31, 2023.

As of September 30, 2024, all available-for-sale marketable securities in an unrealized loss position had been in an unrealized loss position for less than 12 months. As of September 30, 2024, the Company held 13 available-for-sale marketable securities which have been in an unrealized loss position for a period of less than 12 months.

As of September 30, 2024, the following table summarizes the amortized cost and the unrealized gains (losses) of the available-for-sale marketable securities presented within marketable securities, marketable securities, non-current and cash equivalents (in thousands):


	Remaining								Aggregate
	Contractual								Estimated Fair
	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Value
Corporate securities	Less than 1	$	987	$	3	$	—		$	990
Commercial paper	Less than 1		29,851		16		(2	)		29,865
U.S. treasury securities	Less than 1		23,397		14		—			23,411
U.S. government agency securities	Less than 1		10,406		30		(1	)		10,435
Total maturity less than 1 year			64,641		63		(3	)		64,701
Corporate debt securities	1 to 2		942		15		—			957
U.S. government agency securities	1 to 2		5,921		101		—			6,022
Total		$	71,504	$	179	$	(3	)	$	71,680

As of September 30, 2024, the following table summarizes available-for-sale marketable securities in an unrealized loss position (in thousands):


	Less than 12 Months
	Fair Value		Gross Unrealized Loss
Commercial paper	$	16,100	$	(2	)
U.S. treasury securities		5,023		—
U.S. government agency securities		1,592		(1	)
Total	$	22,715	$	(3	)

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense	$ 0.4	$ 0.2	$ 1.0	$ 0.6

Stock-Based Compensation - Summary Of Stock Based Compensation Expense For Restricted Stock Awards And Stock Options (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	$ 683	$ 347	$ 1,888	$ 1,045
Research and Development Expense [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	356	203	968	612
General and Administrative Expense [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 327	$ 144	$ 920	$ 433

Available-for-Sale Marketable Securities and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2024

Available-for-Sale Marketable Securities and Fair Value Measurements [Abstract]

Schedule of Fair Value Measurements on Cash Equivalents and Marketable Securities

The fair value measurements of the Company’s cash equivalents and marketable securities are identified at the following levels within the fair value hierarchy (in thousands):


	September 30, 2024
			Fair Value Measurement
	Total		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	60,991	$	60,991	$	—	$	—
Commercial paper		20,027		—		20,027		—
U.S. treasury securities		1,689		—		1,689		—
U.S. government agency securities		694		—		694		—
Marketable securities, current:
U.S. treasury securities		21,722		—		21,722		—
U.S. government agency securities		9,741		—		9,741		—
Commercial paper		9,838		—		9,838		—
Corporate debt securities		990		—		990		—
Marketable securities, non-current:
U.S. government agency securities		6,022		—		6,022		—
Corporate debt securities		957		—		957		—
Total measured at fair value	$	132,671	$	60,991	$	71,680	$	—


	December 31, 2023
			Fair Value Measurement
	Total		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	86,574	$	86,574	$	—	$	—
Total measured at fair value	$	86,574	$	86,574	$	—	$	—

Summary of Available-for-Sale Marketable Securities by Major Type of Security


	Remaining								Aggregate
	Contractual								Estimated Fair
	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Value
Corporate securities	Less than 1	$	987	$	3	$	—		$	990
Commercial paper	Less than 1		29,851		16		(2	)		29,865
U.S. treasury securities	Less than 1		23,397		14		—			23,411
U.S. government agency securities	Less than 1		10,406		30		(1	)		10,435
Total maturity less than 1 year			64,641		63		(3	)		64,701
Corporate debt securities	1 to 2		942		15		—			957
U.S. government agency securities	1 to 2		5,921		101		—			6,022
Total		$	71,504	$	179	$	(3	)	$	71,680

Schedule of Unrealized Loss Positions of Available-for-Sale Marketable Securities

As of September 30, 2024, the following table summarizes available-for-sale marketable securities in an unrealized loss position (in thousands):


	Less than 12 Months
	Fair Value		Gross Unrealized Loss
Commercial paper	$	16,100	$	(2	)
U.S. treasury securities		5,023		—
U.S. government agency securities		1,592		(1	)
Total	$	22,715	$	(3	)

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
Income Statement [Abstract]
Revenue	$ 176	$ 33	$ 863	$ 33
Operating expenses:
Research and development	17,832	9,281	46,020	25,653
General and administrative	4,894	2,792	10,948	6,622
Total operating expenses	22,726	12,073	56,968	32,275
Loss from operations	(22,550)	(12,040)	(56,105)	(32,242)
Other income, net:
Interest income	1,900	1,096	4,709	1,531
Other expense, net	(9)	(1)	(72)	(3)
Total other income, net	1,891	1,095	4,637	1,528
Loss before benefit for income taxes	(20,659)	(10,945)	(51,468)	(30,714)
Benefit for income taxes	136		338
Net loss attributable to common stockholders	$ (20,523)	$ (10,945)	$ (51,130)	$ (30,714)
Net loss per share attributable to common stockholders - Basic	$ (8.4)	$ (5.45)	$ (21.87)	$ (16.49)
Net loss per share attributable to common stockholders - Diluted	$ (8.4)	$ (5.45)	$ (21.87)	$ (16.49)
Weighted-average shares outstanding - Basic	2,443,678	2,007,620	2,337,891	1,862,036
Weighted-average shares outstanding - Diluted	2,443,678	2,007,620	2,337,891	1,862,036
Comprehensive loss:
Net Income (Loss)	$ (20,523)	$ (10,945)	$ (51,130)	$ (30,714)
Net unrealized gain on available-for-sale marketable securities	184		176
Total other comprehensive income	184		176
Comprehensive loss	$ (20,339)	$ (10,945)	$ (50,954)	$ (30,714)

Subsequent Events - Additional Information (Details) - shares	Jan. 01, 2026	Jan. 01, 2025	Oct. 31, 2024
Forecast [Member] \| 2024 Option and Incentive Plan
Subsequent Event [Line Items]
Percentage of outstanding number of shares of common stock		5.00%
Forecast [Member] \| Maximum [Member] \| 2024 Employee Stock Purchase Plan
Subsequent Event [Line Items]
Number of shares reserved for issuance	369,402
Percentage of outstanding number of shares of common stock	1.00%
Subsequent Event \| 2024 Option and Incentive Plan
Subsequent Event [Line Items]
Number of shares reserved for issuance			3,690,000
Subsequent Event \| Maximum [Member] \| 2024 Employee Stock Purchase Plan
Subsequent Event [Line Items]
Number of shares reserved for issuance			369,402

Condensed Statements of Convertible Preferred Stock and Stockholders' Deficit - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning Balance at Dec. 31, 2022	$ (44,201)			$ 3	$ 6,552		$ (50,756)
Beginning Balance (in shares) at Dec. 31, 2022				3,181,829
Temporary Equity, Beginning Balance at Dec. 31, 2022		$ 74,694
Temporary Equity, Beginning Balance (in shares) at Dec. 31, 2022		75,000,000
Vesting of restricted common stock	6				6
Stock-based compensation expense	343				343
Net loss	(9,171)						(9,171)
Ending Balance at Mar. 31, 2023	(53,023)			$ 3	6,901		(59,927)
Ending Balance (in shares) at Mar. 31, 2023				3,181,829
Temporary Equity, Ending Balance at Mar. 31, 2023		$ 74,694
Temporary Equity, Ending Balance (in shares) at Mar. 31, 2023		75,000,000
Beginning Balance at Dec. 31, 2022	(44,201)			$ 3	6,552		(50,756)
Beginning Balance (in shares) at Dec. 31, 2022				3,181,829
Temporary Equity, Beginning Balance at Dec. 31, 2022		$ 74,694
Temporary Equity, Beginning Balance (in shares) at Dec. 31, 2022		75,000,000
Net loss	(30,714)
Ending Balance at Sep. 30, 2023	(73,849)			$ 3	7,618		(81,470)
Ending Balance (in shares) at Sep. 30, 2023				3,168,134
Temporary Equity, Ending Balance at Sep. 30, 2023		$ 74,694	$ 74,521
Temporary Equity, Ending Balance (in shares) at Sep. 30, 2023		75,000,000	60,828,720
Beginning Balance at Mar. 31, 2023	(53,023)			$ 3	6,901		(59,927)
Beginning Balance (in shares) at Mar. 31, 2023				3,181,829
Temporary Equity, Beginning Balance at Mar. 31, 2023		$ 74,694
Temporary Equity, Beginning Balance (in shares) at Mar. 31, 2023		75,000,000
Issuance of Series B Convertible Preferred Stock, issuance costs			$ 72,021
Issuance of Series B Convertible Preferred Stock, issuance costs (in shares)			58,801,098
Vesting of restricted common stock	9				9
Repurchase of unvested restricted common stock (in shares)				(2,807)
Stock-based compensation expense	355				355
Net loss	(10,598)						(10,598)
Ending Balance at Jun. 30, 2023	(63,257)			$ 3	7,265		(70,525)
Ending Balance (in shares) at Jun. 30, 2023				3,179,022
Temporary Equity, Ending Balance at Jun. 30, 2023		$ 74,694	$ 72,021
Temporary Equity, Ending Balance (in shares) at Jun. 30, 2023		75,000,000	58,801,098
Issuance of Series B Convertible Preferred Stock, issuance costs			$ 2,500
Issuance of Series B Convertible Preferred Stock, issuance costs (in shares)			2,027,622
Vesting of restricted common stock	6				6
Repurchase of unvested restricted common stock (in shares)				(10,888)
Stock-based compensation expense	347				347
Net loss	(10,945)						(10,945)
Ending Balance at Sep. 30, 2023	(73,849)			$ 3	7,618		(81,470)
Ending Balance (in shares) at Sep. 30, 2023				3,168,134
Temporary Equity, Ending Balance at Sep. 30, 2023		$ 74,694	$ 74,521
Temporary Equity, Ending Balance (in shares) at Sep. 30, 2023		75,000,000	60,828,720
Beginning Balance at Dec. 31, 2023	(38,374)			$ 3	8,199		(46,576)
Beginning Balance (in shares) at Dec. 31, 2023				3,168,134
Temporary Equity, Beginning Balance at Dec. 31, 2023	149,215	$ 74,694	$ 74,521
Temporary Equity, Beginning Balance (in shares) at Dec. 31, 2023		75,000,000	60,828,720
Issuance of common stock upon exercise of stock options	1				1
Issuance of common stock upon exercise of stock options (in shares)				217
Vesting of restricted common stock	6				6
Repurchase of unvested restricted common stock (in shares)				(11,517)
Stock-based compensation expense	577				577
Net unrealized gain (loss) on available-for-sale marketable securities	(7)					$ (7)
Net loss	(14,097)						(14,097)
Ending Balance at Mar. 31, 2024	(51,894)			$ 3	8,783	(7)	(60,673)
Ending Balance (in shares) at Mar. 31, 2024				3,156,834
Temporary Equity, Ending Balance at Mar. 31, 2024		$ 74,694	$ 74,521
Temporary Equity, Ending Balance (in shares) at Mar. 31, 2024		75,000,000	60,828,720
Beginning Balance at Dec. 31, 2023	(38,374)			$ 3	8,199		(46,576)
Beginning Balance (in shares) at Dec. 31, 2023				3,168,134
Temporary Equity, Beginning Balance at Dec. 31, 2023	149,215	$ 74,694	$ 74,521
Temporary Equity, Beginning Balance (in shares) at Dec. 31, 2023		75,000,000	60,828,720
Net loss	(51,130)
Ending Balance at Sep. 30, 2024	(87,408)			$ 3	10,119	176	(97,706)
Ending Balance (in shares) at Sep. 30, 2024				3,162,968
Temporary Equity, Ending Balance at Sep. 30, 2024	224,157	$ 74,694	$ 149,463
Temporary Equity, Ending Balance (in shares) at Sep. 30, 2024		75,000,000	121,657,452
Beginning Balance at Mar. 31, 2024	(51,894)			$ 3	8,783	(7)	(60,673)
Beginning Balance (in shares) at Mar. 31, 2024				3,156,834
Temporary Equity, Beginning Balance at Mar. 31, 2024		$ 74,694	$ 74,521
Temporary Equity, Beginning Balance (in shares) at Mar. 31, 2024		75,000,000	60,828,720
Issuance of Series B Convertible Preferred Stock, issuance costs			$ 74,942
Issuance of Series B Convertible Preferred Stock, issuance costs (in shares)			60,828,732
Issuance of common stock upon exercise of stock options	10				10
Issuance of common stock upon exercise of stock options (in shares)				6,186
Vesting of restricted common stock	4				4
Stock-based compensation expense	628				628
Net unrealized gain (loss) on available-for-sale marketable securities	(1)					(1)
Net loss	(16,510)						(16,510)
Ending Balance at Jun. 30, 2024	(67,763)			$ 3	9,425	(8)	(77,183)
Ending Balance (in shares) at Jun. 30, 2024				3,163,020
Temporary Equity, Ending Balance at Jun. 30, 2024		$ 74,694	$ 149,463
Temporary Equity, Ending Balance (in shares) at Jun. 30, 2024		75,000,000	121,657,452
Issuance of common stock upon exercise of stock options	5				5
Issuance of common stock upon exercise of stock options (in shares)				2,730
Vesting of restricted common stock	6				6
Repurchase of unvested restricted common stock (in shares)				(2,782)
Stock-based compensation expense	683				683
Net unrealized gain (loss) on available-for-sale marketable securities	184					184
Net loss	(20,523)						(20,523)
Ending Balance at Sep. 30, 2024	(87,408)			$ 3	$ 10,119	$ 176	$ (97,706)
Ending Balance (in shares) at Sep. 30, 2024				3,162,968
Temporary Equity, Ending Balance at Sep. 30, 2024	$ 224,157	$ 74,694	$ 149,463
Temporary Equity, Ending Balance (in shares) at Sep. 30, 2024		75,000,000	121,657,452

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option awards granted		700,000	0	700,000
Total grant date fair value		$ 10,500,000		$ 12,400,000
Total fair value of shares vested		300,000		900,000
Aggregate fair value of stock options vested		400,000		$ 900,000
Weighted-average period for recognition of expenses related to non-vested share-based compensation arrangements				3 years
Unrecognized stock-based compensation expense		$ 10,200,000		$ 10,200,000
Weighted-average grant-date fair value per share		$ 8.54		$ 6.46
IPO Stock Options [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option awards granted		600,000		600,000
Employees [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option awards granted		1,200,000		1,900,000
Executive Officer And Director Equity Awards [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option awards granted	1,300,000
Incremental stock-based compensation expense				$ 0
Number of shares authorized	900,000
Restricted Stock Awards [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Restricted stock awards, subject to repurchase		679,236		679,236	1,002,044
Performance Conditions [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 5,500,000		$ 5,500,000
unrecognized stock-based compensation expense related to unvested restricted stock awards		$ 300,000		$ 300,000

Balance Sheet Components - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Accrued compensation expense	$ 2,109	$ 2,954
Accrued general and administrative expense	1,845	209
Accrued research and development expense	1,699	829
Accrued income taxes payable	200	200
Other current liabilities	134	85
Accrued expenses and other current liabilities	$ 5,987	$ 4,277

Available-for-Sale Marketable Securities and Fair Value Measurements - Schedule of Fair Values and Continuous Unrealized Loss Positions of Available-for-Sale Marketable Securities (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value	$ 22,715
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses	(3)
U.S. Treasury Securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value	5,023
U.S. Government Agency Securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value	1,592
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses	(1)
Commercial Paper
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value	16,100
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses	$ (2)

Net Loss Per Share - Summary of Potentially Dilutive Securities not Included in Calculation of Diluted Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities	2,986,349	1,170,845
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities	2,380,470	131,812
Unvested Restricted Stock Subject to Repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities	605,879	1,039,033

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2024	Nov. 11, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity File Number	001-42382
Entity Registrant Name	Septerna, Inc.
Entity Central Index Key	0001984086
Entity Tax Identification Number	84-3891440
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	SEPN
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	250 East Grand Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	338-3533
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		44,402,742

Organization and Basis of Presentation (Policies)	9 Months Ended
Organization and Basis of Presentation (Policies)	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reverse Stock Split	Reverse Stock Split On October 18, 2024, the Company effected a 1-for-8.6103 reverse stock split of its issued and outstanding shares of common stock. Upon the effectiveness of the reverse stock split, (i) all shares of outstanding common stock were adjusted; (ii) the conversion ratio of the convertible preferred stock was adjusted; (iii) the number of shares of common stock for which each outstanding option to purchase common stock is exercisable were adjusted; and (iv) the exercise price of each outstanding option to purchase common stock was adjusted. All of the outstanding common stock (including shares of common stock subject to the Company’s options and as converted for the outstanding convertible preferred stock), share prices, exercise prices and per share amounts contained in the condensed financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. The number of authorized shares did not change.
Initial Public Offering	Initial Public Offering In October 2024, the Company completed its initial public offering (“IPO”), pursuant to which it issued and sold an aggregate of 18.4 million shares of its common stock at the IPO price of $18.00 per share, including 2.4 million shares that were issued to the underwriters pursuant to the full exercise of their option to purchase additional shares, resulting in net proceeds of approximately $302.6 million, after deducting underwriting discounts, commissions and other offering expenses payable by the Company of approximately $28.6 million. Immediately prior to the closing of the IPO, the Company’s outstanding convertible preferred stock automatically converted into 22,839,774 shares of common stock. Following the closing of the IPO, no shares of convertible preferred stock were authorized or outstanding. In connection with the completion of the IPO, on October 28, 2024, the Company’s certificate of incorporation was amended and restated to (i) authorize 500.0 million shares of common stock, par value $0.001 per share, which eliminates all references to the previously existing series of convertible preferred stock; and (ii) authorize 10.0 million shares of undesignated preferred stock, par value $0.001 per share, that may be issued from time to time by the Company’s board of directors in one or more series. The Company’s unaudited condensed financial statements as of September 30, 2024, including share and per share amounts, do not give effect to the IPO and related actions as it closed subsequent to September 30, 2024.
Liquidity and Capital Resources	Liquidity and Capital Resources The accompanying unaudited condensed financial statements have been prepared assuming the Company will continue as a going concern, which assumes that the Company will realize its assets and satisfies its liabilities in the normal course of business. The Company is subject to risks inherent in operating an early-stage biotechnology business. These risks include, but are not limited to, dependence on the development of marketable products, the ability to attract, retain, and motivate qualified personnel, rapid technological changes and the rapidly evolving nature of the biotechnology industry. The Company has incurred significant losses and negative cash flows from operations since its inception and expects to incur losses as a result of its continued research and development activities. To date, none of the Company’s product candidates have been approved by the U.S. Food and Drug Administration (the “FDA”) for commercial sale and, therefore, the Company has not generated any revenue from product sales. The Company historically financed its operations primarily through the issuances of convertible promissory notes and convertible preferred stock, and most recently, through sale of its common stock in an IPO. The Company will need additional financing to support its continuing operations and pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, it expects to finance its operations through equity offerings, debt financings or other capital sources, including collaborations with other companies or other strategic transactions. The Company may not be able to obtain funding on acceptable terms, or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. For the nine months ended September 30, 2024 and 2023, the Company incurred net losses of $51.1 million and $30.7 million, respectively. The Company had an accumulated deficit of $97.7 million as of September 30, 2024. The Company expects to continue to generate operating losses for the foreseeable future. The Company believes its cash, cash equivalents, marketable securities, and marketable securities, non-current of $137.5 million as of September 30, 2024, together with the net proceeds of approximately $302.6 million from its IPO, will be sufficient to fund its operations for, at least, 12 months from the date of issuance of the unaudited condensed financial statements.
Basis of Presentation	Basis of Presentation The accompanying unaudited interim condensed financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act of 1933, as amended (the “Securities Act”), and reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for the fair presentation of the Company’s unaudited interim condensed financial statements as of September 30, 2024 and December 31, 2023, and for the three and nine months ended September 30, 2024 and 2023. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Updates (“ASUs”), of the Financial Accounting Standards Board (“FASB”). The interim condensed financial statements are unaudited. The operating results presented in these unaudited interim condensed financial statements are not necessarily indicative of the results that may be expected for the full year or for any other future annual or interim period. Actual results could differ materially from estimates and assumptions. As appropriate, the Company assesses estimates each period and updates them to reflect current information, and generally reflect any changes in estimates in the period first identified. These unaudited interim condensed financial statements should be read in conjunction with the Company's audited financial statements for the year ended December 31, 2023 and notes thereto, included in the Company’s final IPO prospectus filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) under the Securities Act on October 25, 2024.
Significant Accounting Policies	Significant Accounting Policies During the nine months ended September 30, 2024, there were no changes to the Company’s significant accounting policies as described in Note 2 of the audited financial statements for the year ended December 31, 2023 as referenced above, other than the policies outlined below.
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities The Company holds marketable securities that consist of highly liquid, investment grade debt securities. The Company's cash and marketable securities are held or issued by financial institutions that management believes are of high credit quality. Marketable securities are classified and accounted for as available-for-sale. Available-for-sale marketable securities with original maturities of 90 days or less are classified as cash equivalents. Available-for-sale marketable securities with original maturities over 90 days and remaining maturities of less than 12 months are classified as current. Available-for-sale marketable securities with remaining maturities of more than 12 months for which the Company has the intent and ability to hold the security for more than 12 months are classified as non-current. The Company’s marketable securities are carried at estimated fair value, which is derived from independent pricing sources based on quoted prices in active markets for similar securities. Unrealized gains and losses are reported in stockholders’ deficit as accumulated other comprehensive income (loss). The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in interest income on the condensed statements of operations and comprehensive loss. The Company has the ability, if necessary, to liquidate any of its cash equivalents and available-for-sale marketable securities to meet its liquidity needs in the next 12 months. After consideration of the Company’s objectives to preserve capital, as well as its liquidity requirements, it may sell these available-for-sale marketable securities prior to their stated maturities. The Company reviews its portfolio of available-for-sale marketable securities, using both quantitative and qualitative factors, to determine if declines in fair value below amortized cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, the Company recognizes a loss in its condensed statement of operations, whereas if the decline in fair value is not due to credit-related factors, the Company recognizes the loss in other comprehensive loss. The Company excludes the applicable accrued interest from both the fair value and amortized cost basis of available-for-sale marketable securities for purposes of identifying and measuring an impairment. Accrued interest receivable on available-for-sale marketable securities is recorded within prepaid expenses and other current assets on the interim condensed balance sheets. The Company’s accounting policy is to not measure an allowance for credit loss for accrued interest receivable and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which is considered to be in the period in which it is determined the accrued interest will not be collected.
Deferred Offering Costs	Deferred Offering Costs The Company’s deferred offering costs consist of legal, accounting and other general and administrative costs directly attributable to the Company’s IPO. As of September 30, 2024, $3.2 million of deferred offering costs were included within other non-current assets in the Company’s condensed balance sheet. As of December 31, 2023, there were no deferred offering costs. Upon the consummation of the Company's IPO in October 2024, these costs will be reclassified to additional paid-in capital in stockholders' equity in the Company's condensed balance sheets.
Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements Not Yet Adopted From time to time, new accounting pronouncements are issued by the FASB, under its Accounting Standards Codification (“ASC”) or other standard setting bodies, and adopted by the Company as of the specified date. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. ASU 2023-07 will improve reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses on an interim and annual basis. The ASU is effective for fiscal years beginning after December 15, 2023, and interim periods after December 5, 2024, with early adoption permitted. The Company is currently evaluating the impact of ASU 2023-07 on its financial statements and related disclosures. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the transparency and decision usefulness of income tax disclosures. The standard is intended to improve income tax disclosures primarily related to the rate reconciliation and income taxes paid information. This update also includes certain other amendments to improve the effectiveness of income tax disclosures. The ASU is effective for fiscal years beginning after December 15, 2024, on a prospective basis with early adoption and retrospective reporting permitted. The Company is currently evaluating the impact of ASU 2023-09 on its financial statements and related disclosures.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

Note 8. Stock-Based Compensation

Executive Officer and Director Equity Awards Modification

In May 2024, the Company’s board of directors modified the terms of stock option awards for 1.3 million shares of the Company’s common stock and restricted stock awards for 0.9 million shares of the Company's common stock to certain executive officers and members of the Company’s board of directors. Under the modified terms, accelerated vesting provisions were added associated with certain change of control events. No incremental stock-based compensation expense was recognized as a result of the modification.

Restricted Stock Awards

The following summarizes restricted stock award activity under the 2021 Plan:


	Number of Shares Outstanding			Weighted-Average Grant Date Fair Value Per Share
Balance at December 31, 2023		774,225		$	2.32
Restricted stock awards vested		(251,493	)		2.54
Restricted stock awards repurchased		(14,299	)		2.31
Balance at September 30, 2024		508,433			2.27

The following summarizes restricted stock award activity outside of the 2021 Plan:


	Number of Shares Outstanding			Weighted-Average Grant Date Fair Value Per Share
Balance at December 31, 2023		227,819		$	3.79
Restricted stock awards vested		(57,016	)		3.77
Balance at September 30, 2024		170,803			3.75

Restricted stock awards of 679,236 and 1,002,044 shares were subject to repurchase as of September 30, 2024 and December 31, 2023, respectively. The total fair value of shares vested during the three and nine months ended September 30, 2024 was $0.3 million and $0.9 million, respectively.

Stock Options

The following summarizes stock option activity under the 2021 Plan:


	Options Outstanding
	Total Options Outstanding			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2023		1,123,296		$	2.62		9.78	$	2,287
Granted		1,925,905			5.35
Exercised		(9,133	)		1.76
Forfeited		(21,850	)		2.02
Expired		(145	)		2.76
Outstanding as of September 30, 2024		3,018,073			4.37		9.52		19,840
Exercisable as of September 30, 2024		385,048			2.60		9.09		3,212
Vested and expected to vest as of September 30, 2024		3,018,073			4.37		9.52		19,840

The aggregate fair value of stock options that vested for the three and nine months ended September 30, 2024 was $0.4 million and $0.9 million. The stock options granted in the three months ended September 30, 2024 had a weighted-average grant-date fair value per share of $8.54 and a total grant-date fair value of $10.5 million. The options granted in the nine months ended September 30, 2024 had a weighted-average grant-date fair value per share of $6.46 and a total grant date fair value of $12.4 million.

During the three and nine months ended September 30, 2024, the Company granted a total of 1.2 million and 1.9 million shares of stock options to its employees, respectively. A total of 0.6 million of the stock options granted in the three and nine months ended September 30, 2024 include vesting criteria subject to both service conditions and the achievement of performance-based conditions, related to the consummation of the Company’s IPO or a Sale Event, while the remainder include vesting criteria subject to service conditions only. A total of 0.7 million of the stock options granted in the three and nine months ended September 30, 2024 also include accelerated vesting provisions associated with certain change of control events.

Stock Option Valuation

The weighted-average assumptions used to value employee and non-employee stock option awards granted under the 2021 Plan using the Black Scholes option pricing model, were as follows:


	Three Months Ended September 30,					Nine Months Ended September 30,
	2024			2023		2024			2023
Fair value of common stock	$	8.54			—	$	6.46		$	2.74
Risk-free interest rate		3.59	%		—		3.83	%		3.58	%
Expected volatility		90.7	%		—		91.2	%		80.6	%
Expected term (years)		6.05			—		6.03			6.00
Expected dividend yield	—%				—	—%			—%

There were no stock options granted during the three months ended September 30, 2023.

Stock-based Compensation Expense

Stock-based compensation expense for restricted stock awards and stock options recognized in the Company’s condensed statements of operations and comprehensive loss is presented as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development expense	$	356	$	203	$	968	$	612
General and administrative expense		327		144		920		433
Total stock-based compensation expense	$	683	$	347	$	1,888	$	1,045

As of September 30, 2024, total unrecognized stock-based compensation expense related to unvested restricted stock awards and unvested stock options was $10.2 million, which is expected to be recognized over a weighted-average period of 3.0 years.

As of September 30, 2024, total unrecognized stock-based compensation expense related to unvested restricted stock awards and unvested stock options subject to performance conditions, which were improbable of achievement, was $0.3 million and $5.5 million, respectively.

Common Stock (Tables)

9 Months Ended

Sep. 30, 2024

Common Stock, Number of Shares, Par Value and Other Disclosure [Abstract]

Summary of Common Stock Shares Reserved for Future Issuance on Convertible Basis

The Company reserved the following shares of common stock, on an as-converted basis, for future issuance:


	As of September 30,		As of December 31,
	2024		2023
Series A Convertible Preferred Stock		8,710,490		8,710,490
Series B Convertible Preferred Stock		14,129,284		14,129,284
Restricted stock outstanding under 2021 Plan		508,433		774,225
Restricted stock outstanding outside of 2021 Plan		170,803		227,819
Options issued and outstanding under 2021 Plan		3,018,073		1,123,296
Shares reserved for future grants under 2021 Plan		906,277		1,634,488
		27,443,360		26,599,602

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (20,523)	$ (16,510)	$ (14,097)	$ (10,945)	$ (10,598)	$ (9,171)	$ (51,130)	$ (30,714)

- Definition

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

+ References

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+ Details

Related Parties - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Cash proceeds on shares issued			$ 74,942	$ 74,521
Third Rock Ventures \| Series B Preferred Stock
Related Party Transaction [Line Items]
Issuance of Series B Convertible Preferred Stock( in shares)			12,400,000	12,400,000
Cash proceeds on shares issued			$ 15,300	$ 15,200
Third Rock Ventures \| Related Party
Related Party Transaction [Line Items]
General and administrative expenses	$ 100	$ 100	200	200
Outstanding accounts payable	100		100		$ 100
Third Rock Ventures \| Interim Chief Medical Officer
Related Party Transaction [Line Items]
Total fees	$ 100	$ 100	$ 200	$ 200
Options to purchase	23,227		23,227
Exercise price	$ 2.76		$ 2.76
RA Capital \| Series B Preferred Stock
Related Party Transaction [Line Items]
Issuance of Series B Convertible Preferred Stock( in shares)			12,200,000	12,200,000
Cash proceeds on shares issued			$ 15,000	$ 15,000
Samsara BioCapital \| Series B Preferred Stock
Related Party Transaction [Line Items]
Issuance of Series B Convertible Preferred Stock( in shares)			4,300,000	4,300,000
Cash proceeds on shares issued			$ 5,200	$ 5,200

Stock-Based Compensation - Schedule of Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total Options outstanding, Granted	700,000	0	700,000
2021 Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total Options outstanding, Beginning balance			1,123,296
Total Options outstanding, Granted			1,925,905
Total Options outstanding, Exercised			(9,133)
Total Options Outstanding, Forfeited			(21,850)
Total Options Outstanding, Expired			(145)
Total Options outstanding, Ending Balance	3,018,073		3,018,073	1,123,296
Exercisable as of September 30, 2024	385,048		385,048
Vested and expected to vest as of September 30, 2024	3,018,073		3,018,073
Weighted average exercise price, Beginning balance			$ 2.62
Weighted average exercise price, Granted			5.35
Weighted average exercise price, Exercised			1.76
Weighted average exercise price, Forfeited			2.02
Weighted average exercise price, Expired			2.76
Weighted average exercise price, Ending balance	$ 4.37		4.37	$ 2.62
Exercisable as of September 30, 2024	2.6		2.6
Vested and expected to vest as of September 30, 2024	$ 4.37		$ 4.37
Weighted Average Remaining Contractual Life, Outstanding			9 years 6 months 7 days	9 years 9 months 10 days
Exercisable as of September 30, 2024			9 years 1 month 2 days
Vested and expected to vest as of September 30, 2024			9 years 6 months 7 days
Aggregate Intrinsic Value, Outstanding	$ 19,840		$ 19,840	$ 2,287
Exercisable as of September 30, 2024	3,212		3,212
Vested and expected to vest as of September 30, 2024	$ 19,840		$ 19,840

Available-for-Sale Marketable Securities and Fair Value Measurements - Summary of Available-for-Sale Marketable Securities by Major Type of Security (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Debt Securities, Available-for-Sale [Line Items]
Amortized cost of marketable debt securities, contractual maturity, less than one year	$ 64,641
Unrealized gains of marketable debt securites, contractual maturity, less than one year	63
Unrealized losses of marketble debt securities, contractual maturity, less than one year	(3)
Aggregate estimated fair value of marketable debt securities, contractual maturities, less than one year	64,701
Amortized Cost	71,504
Unrealized Gains	179
Unrealized Losses	(3)
Aggregate Estimated Fair Value	71,680
U.S. Treasury Securities
Debt Securities, Available-for-Sale [Line Items]
Amortized cost of marketable debt securities, contractual maturity, less than one year	23,397
Unrealized gains of marketable debt securites, contractual maturity, less than one year	14
Aggregate estimated fair value of marketable debt securities, contractual maturities, less than one year	23,411
U.S. Government Agency Securities
Debt Securities, Available-for-Sale [Line Items]
Amortized cost of marketable debt securities, contractual maturity, less than one year	10,406
Unrealized gains of marketable debt securites, contractual maturity, less than one year	30
Unrealized losses of marketble debt securities, contractual maturity, less than one year	(1)
Aggregate estimated fair value of marketable debt securities, contractual maturities, less than one year	10,435
Amortized cost of marketable debt securities, contractual maturity, one year to two years	5,921
Unrealized gains of marketable debt securities, contractual maturity, one year to two years	101
Aggregate estimated fair value of marketable debt securities, contractual maturities, one year to two year	6,022
Corporate Debt Securities
Debt Securities, Available-for-Sale [Line Items]
Amortized cost of marketable debt securities, contractual maturity, less than one year	987
Unrealized gains of marketable debt securites, contractual maturity, less than one year	3
Aggregate estimated fair value of marketable debt securities, contractual maturities, less than one year	990
Amortized cost of marketable debt securities, contractual maturity, one year to two years	942
Unrealized gains of marketable debt securities, contractual maturity, one year to two years	15
Aggregate estimated fair value of marketable debt securities, contractual maturities, one year to two year	957
Commercial Paper
Debt Securities, Available-for-Sale [Line Items]
Amortized cost of marketable debt securities, contractual maturity, less than one year	29,851
Unrealized gains of marketable debt securites, contractual maturity, less than one year	16
Unrealized losses of marketble debt securities, contractual maturity, less than one year	(2)
Aggregate estimated fair value of marketable debt securities, contractual maturities, less than one year	$ 29,865

Revenue - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
Revenue - Additional Information (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Service revenue	$ 176,000	$ 33,000	$ 863,000	$ 33,000
Vertex Research Service Agreement
Disaggregation of Revenue [Line Items]
Service revenue	$ 200,000		$ 900,000

- Definition

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

+ References + Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

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

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 88,242	$ 88,483
Marketable securities	42,291
Accounts receivable	210	151
Other receivable related to sale of non-financial asset		22,625
Prepaid expenses and other current assets	2,668	1,419
Total current assets	133,411	112,678
Marketable securities, non-current	6,979
Property and equipment, net	5,412	4,665
Operating lease right-of-use asset	24,095	12,522
Restricted cash	905	905
Other non-current assets	3,479	97
Total assets	174,281	130,867
Current liabilities:
Accounts payable	6,128	2,637
Accrued expenses and other current liabilities	5,987	4,277
Operating lease liability, current	1,116
Total current liabilities	13,231	6,914
Operating lease liability, non-current	24,110	12,566
Other non-current liabilities	191	546
Total liabilities	37,532	20,026
Commitments and contingencies (Note 5)
Convertible preferred stock	224,157	149,215
Stockholders' deficit:
Common stock	3	3
Additional paid-in capital	10,119	8,199
Accumulated other comprehensive income	176
Accumulated deficit	(97,706)	(46,576)
Total stockholders' deficit	(87,408)	(38,374)
Total liabilities, convertible preferred stock and stockholders' deficit	$ 174,281	$ 130,867

Common Stock - Summary of Common Stock Shares Reserved for Future Issuance on Convertible Basis (Details) - shares	Sep. 30, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Common stock reserved for future issuance	27,443,360	26,599,602
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	8,710,490	8,710,490
Series B Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	14,129,284	14,129,284
Restricted Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	170,803	227,819
Stock 2021 Plan [Member] \| Restricted Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	508,433	774,225
Stock 2021 Plan [Member] \| Employee Stock Option
Class of Stock [Line Items]
Common stock reserved for future issuance	3,018,073	1,123,296
Stock 2021 Plan [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	906,277	1,634,488

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
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Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
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-URI https://asc.fasb.org/1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Commitments and Contingencies - Additional Information (Details)	Sep. 30, 2024 USD ($) ft²	Dec. 31, 2023 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease right-of-use asset	$ 24,095,000	$ 12,522,000
liabilities associated with indemnification rights and agreements	0	$ 0
Original Leased Space
Lessee, Lease, Description [Line Items]
Operating lease right-of-use asset	$ 12,500,000
Renovations of square foot office and research and development space \| ft²	21,908
Remaining lease term of Original Leased Space	7 years 9 months 18 days
Percentage of present value of lease payments	10.44%

Stock-Based Compensation - Summary of Weighted-Average Assumptions used for Grants Awards (Details) - Stock 2021 Plan [Member] - $ / shares	3 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Fair value of common stock	$ 8.54	$ 6.46	$ 2.74
Risk-free interest rate	3.59%	3.83%	3.58%
Expected volatility	90.70%	91.20%	80.60%
Expected term (years)	6 years 18 days	6 years 10 days	6 years

- Definition

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

+ References

+ Details

Commitments and Contingencies

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 5. Commitments and Contingencies

Leases

During the three months ended September 30, 2024, the Company recorded a $12.5 million operating lease right-of-use asset and operating lease liability upon completion of the renovations of the 21,908 square foot office and research and development space (the "Original Leased Space") and as the Company occupied the property.

As of September 30, 2024, the remaining lease term of the Original Leased Space was approximately 7.8 years. The incremental borrowing rate used for the calculation of the present value of lease payments over the lease term at the lease commencement date was approximately 10.44%.

As of September 30, 2024, future minimum rental payments for operating leases, including for the Original Leased Space, were as follows (in thousands):


As of September 30,	Future Payments
2024 (remaining three months)	$	437
2025		4,469
2026		4,612
2027		4,760
2028		4,912
Thereafter		18,921
Total lease payments		38,111
Less: imputed interest		(12,885	)
Total present value of operating lease liability	$	25,226

Operating lease liability, current	$	1,116
Operating lease liability, non-current		24,110
Total operating lease liability	$	25,226

Legal Proceedings

In the ordinary course of business, the Company may be subject to legal proceedings, claims and litigation, as the Company operates in an industry susceptible to patent or other legal claims. The Company accounts for estimated losses with respect to legal proceedings and claims when such losses are probable and estimable. Legal costs associated with these matters are expensed when incurred. The Company was not subject to any material legal proceedings as of September 30, 2024 and December 31, 2023, and the Company is not currently a party to any legal proceeding that, if determined adversely to the Company, in management’s opinion, is currently expected to individually or in the aggregate have a material adverse effect on the Company’s business, financial condition or results of operations taken as a whole.

Indemnifications

In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. As permitted under Delaware law and in accordance with its bylaws, the Company indemnifies its officers and directors for certain events or occurrences while the officer or director is or was serving in such capacity. The Company is also party to indemnification agreements with its officers and directors.

The maximum potential amount of future payments that the Company could be required to make under these provisions is not determinable; however, the Company currently holds director and officer liability insurance. This insurance limits the Company’s exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. In addition, the Company is not currently aware of any indemnification claims. Accordingly, the Company did not record any liabilities associated with these indemnification rights and agreements as of September 30, 2024 and December 31, 2023.

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2024

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of Restricted Stock Award Activity

The following summarizes restricted stock award activity outside of the 2021 Plan:


	Number of Shares Outstanding			Weighted-Average Grant Date Fair Value Per Share
Balance at December 31, 2023		227,819		$	3.79
Restricted stock awards vested		(57,016	)		3.77
Balance at September 30, 2024		170,803			3.75

Summary Of Stock Based Compensation Expense For Restricted Stock Awards And Stock Options


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development expense	$	356	$	203	$	968	$	612
General and administrative expense		327		144		920		433
Total stock-based compensation expense	$	683	$	347	$	1,888	$	1,045

2021 Plan [Member]

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Schedule of Restricted Stock Award Activity

The following summarizes restricted stock award activity under the 2021 Plan:


	Number of Shares Outstanding			Weighted-Average Grant Date Fair Value Per Share
Balance at December 31, 2023		774,225		$	2.32
Restricted stock awards vested		(251,493	)		2.54
Restricted stock awards repurchased		(14,299	)		2.31
Balance at September 30, 2024		508,433			2.27

Schedule of Stock Options Activity

The following summarizes stock option activity under the 2021 Plan:


	Options Outstanding
	Total Options Outstanding			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2023		1,123,296		$	2.62		9.78	$	2,287
Granted		1,925,905			5.35
Exercised		(9,133	)		1.76
Forfeited		(21,850	)		2.02
Expired		(145	)		2.76
Outstanding as of September 30, 2024		3,018,073			4.37		9.52		19,840
Exercisable as of September 30, 2024		385,048			2.60		9.09		3,212
Vested and expected to vest as of September 30, 2024		3,018,073			4.37		9.52		19,840

Summary of Weighted Average Assumptions used for Grants Awards

The weighted-average assumptions used to value employee and non-employee stock option awards granted under the 2021 Plan using the Black Scholes option pricing model, were as follows:


	Three Months Ended September 30,					Nine Months Ended September 30,
	2024			2023		2024			2023
Fair value of common stock	$	8.54			—	$	6.46		$	2.74
Risk-free interest rate		3.59	%		—		3.83	%		3.58	%
Expected volatility		90.7	%		—		91.2	%		80.6	%
Expected term (years)		6.05			—		6.03			6.00
Expected dividend yield	—%				—	—%			—%

- Definition

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

+ References

+ Details

Commitments and Contingencies - Schedule of Future Minimum Rental Payments for Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
2024 (remaining three months)	$ 437
2025	4,469
2026	4,612
2027	4,760
2028	4,912
Thereafter	18,921
Total lease payments	38,111
Less: imputed interest	(12,885)
Total present value of operating lease liability	25,226
Operating lease liability, current	1,116
Operating lease liability, non-current	$ 24,110	$ 12,566

Convertible Preferred Stock - Summary of Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Temporary Equity [Line Items]
Convertible preferred stock, carrying value	$ 224,157			$ 149,215
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized	75,000,000			75,000,000
Convertible preferred stock, shares issued	75,000,000			75,000,000
Convertible preferred stock, shares outstanding	75,000,000	75,000,000	75,000,000	75,000,000	75,000,000	75,000,000	75,000,000	75,000,000
Convertible preferred stock, carrying value	$ 74,694	$ 74,694	$ 74,694	$ 74,694	$ 74,694	$ 74,694	$ 74,694	$ 74,694
Convertible preferred stock, liquidation preference	$ 75,000			$ 75,000
Conversion price per share	$ 1			$ 1
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized	121,657,452			121,657,452
Convertible preferred stock, shares issued	121,657,452			60,828,720
Convertible preferred stock, shares outstanding	121,657,452	121,657,452	60,828,720	60,828,720	60,828,720	58,801,098
Convertible preferred stock, carrying value	$ 149,463	$ 149,463	$ 74,521	$ 74,521	$ 74,521	$ 72,021
Convertible preferred stock, liquidation preference	$ 150,000			$ 75,000
Conversion price per share	$ 1.23297			$ 1.23297

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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-Section S99
-Paragraph 1
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Convertible Preferred Stock (Tables)

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Summary of Convertible Preferred Stock

As of September 30, 2024, the Company's convertible preferred stock consisted of the following (in thousands, except for share and per share amounts):


Series	Authorized Shares		Issued and Outstanding		Carrying Value		Liquidation Preference		Conversion Price Per Share
Series A		75,000,000		75,000,000	$	74,694	$	75,000	$	1.00000
Series B		121,657,452		121,657,452		149,463		150,000		1.23297

As of December 31, 2023, the Company's convertible preferred stock consisted of the following (in thousands, except for share and per share amounts):


Series	Authorized Shares		Issued and Outstanding		Carrying Value		Liquidation Preference		Conversion Price Per Share
Series A		75,000,000		75,000,000	$	74,694	$	75,000	$	1.00000
Series B		121,657,452		60,828,720		74,521		75,000		1.23297

Subsequent Events

9 Months Ended

Sep. 30, 2024

Subsequent Events [Abstract]

Subsequent Events

Note 11. Subsequent Events

2024 Plan

In October 2024, the Company's board of directors adopted, and its stockholders approved, the 2024 Option and Incentive Plan (the “2024 Plan”), which became effective upon the date immediately preceding the date on which the IPO registration statement was declared effective by the SEC. The 2024 Plan allows for the issuance of equity-based and cash-based incentive awards to the Company's officers, employees, directors and consultants. The 2024 Plan is administered by the Company's compensation committee. The exercise prices, vesting and other restrictions are determined at the discretion of the compensation committee, subject to the provisions of the 2024 Plan.

The Company initially reserved for issuance under the 2024 Plan 3,690,000 shares of its common stock. The 2024 Plan provides that the number of shares reserved and available for issuance under the 2024 Plan will automatically increase on January 1, 2025 and each January 1 thereafter through January 1, 2034, by 5% of the outstanding number of shares of the Company's common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Company's compensation committee.

The number of shares reserved under the 2024 Plan is subject to adjustment in the event of a stock split, stock dividend or other change in the Company's capitalization. The 2024 Plan replaced the 2021 Plan as the Company’s board of directors determined not to make additional awards under the 2021 Plan following the completion of the IPO. However, the 2021 Plan will continue to govern outstanding equity awards granted thereunder. The shares of common stock underlying any awards under the 2024 Plan and the 2021 Plan that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire or are otherwise terminated (other than by exercise) will be added to the shares of the Company's common stock available for issuance under the 2024 Plan.

2024 ESPP

In October 2024, the Company's board of directors adopted, and its stockholders approved, the 2024 Employee Stock Purchase Plan (the “2024 ESPP”), which became effective upon the date immediately preceding the date on which the IPO registration statement was declared effective by the SEC. The 2024 ESPP initially reserved and authorized the issuance of up to a total of 369,402 shares of the Company’s common stock to participating employees. The 2024 ESPP provides that the number of shares reserved and available for issuance will automatically increase on January 1, 2026 and each January 1 thereafter through January 1, 2034, by the lesser of (i) 369,402 shares of common stock, (ii) 1% of the outstanding number of shares of common stock on the immediately preceding December

31, or (iii) such lesser number of shares of common stock as determined by the administrator of the 2024 ESPP. The number of shares reserved under the 2024 ESPP is subject to adjustment in the event of a stock split, stock dividend or other change in the Company's capitalization.

Balance Sheet Components - Summary of Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Prepaid expenses	$ 1,152	$ 874
Prepaid clinical trial costs	679
Prepaid bonus	241	378
Prepaid taxes	232	75
Interest receivable	123
Other current assets	241	92
Prepaid expenses and other current assets	$ 2,668	$ 1,419

Condensed Statements of Convertible Preferred Stock and Stockholders' Deficit (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2024	Sep. 30, 2023	Jun. 30, 2023
Series B Convertible Preferred Stock
Issuance costs	$ 58	$ 0	$ 479

Balance Sheet Components

9 Months Ended

Sep. 30, 2024

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

Note 2. Balance Sheet Components

Restricted Cash

Restricted cash is comprised of cash that is restricted as to withdrawal or use under the terms of certain contractual agreements. In connection with the Company’s lease agreement, the Company is required to maintain a collateral account to secure a letter of credit issued to its landlord. The collateral account is classified as restricted cash on the Company’s condensed balance sheets.

Accounts Receivable and Other Receivables

The Company assessed if an allowance for expected credit losses over the life of its receivables should be reserved for based on a combination of historical experience, aging analysis, current economic trends and information on specific accounts, with related amounts recorded as a reserve against revenue recognized. The reserve is re-evaluated on a regular basis and adjusted as needed. Once a receivable is deemed to be uncollectible, such balance is charged against the reserve. Based on its assessment, as of September 30, 2024 and December 31, 2023, the Company determined that an allowance for credit loss was not required.

As of September 30, 2024, the Company’s accounts receivable was entirely attributed to Vertex Pharmaceuticals Incorporated (“Vertex”). As of December 31, 2023, the Company’s accounts receivable and other receivable related to sale of non-financial asset balances were entirely attributed to Vertex.

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):


	As of September 30,		As of December 31,
	2024		2023
Prepaid expenses	$	1,152	$	874
Prepaid clinical trial costs		679		—
Prepaid bonus		241		378
Prepaid taxes		232		75
Interest receivable		123		—
Other current assets		241		92
Prepaid expenses and other current assets	$	2,668	$	1,419

Property and Equipment, Net

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


	As of September 30,			As of December 31,
	2024			2023
Lab equipment	$	5,613		$	4,967
Furniture, fixtures, and office equipment		1,222			713
Leasehold improvements		717			389
Computer equipment		401			218
Total property and equipment		7,953			6,287
Less: Accumulated depreciation and amortization		(2,541	)		(1,622	)
Property and equipment, net	$	5,412		$	4,665

Depreciation and amortization expense was $0.4 million and $1.0 million for the three and nine months ended September 30, 2024, respectively. Depreciation and amortization expense was $0.2 million and $0.6 million for the three and nine months ended September 30, 2023, respectively.

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following (in thousands):


	As of September 30,		As of December 31,
	2024		2023
Accrued compensation expense	$	2,109	$	2,954
Accrued general and administrative expense		1,845		209
Accrued research and development expense		1,699		829
Accrued income taxes payable		200		200
Other current liabilities		134		85
Accrued expenses and other current liabilities	$	5,987	$	4,277

Related Parties

9 Months Ended

Sep. 30, 2024

Related Parties

Note 9. Related Parties

Third Rock Ventures

During the nine months ended September 30, 2024, the Company issued a total of 12.4 million shares of its Series B Convertible Preferred Stock to Third Rock Ventures VI, L.P., a holder of more than 5% of the Company’s outstanding capital stock, during the second tranche closing in May 2024, for cash proceeds of $15.3 million.

During the nine months ended September 30, 2023, the Company issued a total of 12.4 million shares of its Series B Convertible Preferred Stock to Third Rock Ventures V, L.P., a holder of more than 5% of the Company’s outstanding capital stock, during the first tranche closing in June 2023, for cash proceeds of $15.2 million.

In August 2021, the Company entered into a service agreement with Third Rock Ventures, LLC (“TRV”), a holder of more than 5% of the Company’s outstanding capital stock, (the “TRV service agreement”) under which TRV provides consulting services to the Company. For the three and nine months ended September 30, 2024, under the TRV service agreement, the Company incurred fees of $0.1 million and $0.2 million, respectively, which were recorded within general and administrative expenses in the Company’s condensed statements of operations and comprehensive loss. For the three and nine months ended September 30, 2023, under the TRV service agreement, the Company incurred fees of $0.1 million and $0.2 million, respectively, which were recorded within general and administrative expenses in the Company’s condensed statements of operations and comprehensive loss. As of December 31, 2023 and September 30, 2024, outstanding accounts payable to TRV was $0.1 million.

For the three and nine months ended September 30, 2024, of the total fees under the TRV service agreement, $0.1 million and $0.2 million, respectively, were attributed to the Company's interim Chief Medical Officer. For the three and nine months ended September 30, 2023, of the total fees under the TRV service agreement, $0.1 million and $0.2 million, respectively, were attributed to the Company's interim Chief Medical Officer. Additionally, the Company granted its interim Chief Medical Officer options to purchase 23,227 shares during the nine months ended September 30, 2024, at exercise prices of $2.76 per share.

RA Capital

During the nine months ended September 30, 2024, the Company issued a total of 12.2 million shares of its Series B Convertible Preferred Stock to entities affiliated with RA Capital Management, L.P. (collectively, “RA Capital”), which held more than 5% of the Company’s outstanding capital stock, during the second tranche closing in May 2024, for total cash proceeds of $15.0 million. During the nine months ended September 30, 2023, the Company issued a total of 12.2 million shares of its Series B Convertible Preferred Stock to RA Capital during the first tranche closing in June 2023, for total cash proceeds of $15.0 million.

Samsara BioCapital

During the nine months ended September 30, 2024, the Company issued a total of 4.3 million shares of its Series B Convertible Preferred Stock to Samsara BioCapital, L.P. (“Samsara BioCapital”), a holder of more than 5% of the Company’s outstanding capital stock, during the second tranche closing in May 2024, for cash proceeds of $5.2 million. During the nine months ended September 30, 2023, the Company issued a total of 4.3 million shares of its Series B Convertible Preferred Stock to Samsara BioCapital during the first tranche closing in June 2023, for cash proceeds of $5.2 million.

- Definition

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

+ References

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+ Details

Revenue

9 Months Ended

Sep. 30, 2024

Revenue from Contract with Customer [Abstract]

Revenue

Note 3. Revenue

The Company recognizes service revenue associated with the Vertex Research Service Agreement (the “Vertex Research Service Agreement”) over the performance period of the research services as the services are provided in accordance with ASC Topic 606, Revenue from Contracts with Customers (“ASC Topic 606”).

During the three and nine months ended September 30, 2024, the Company recorded service revenue of $0.2 million and $0.9 million related to research activities performed in connection with the Vertex Research Service Agreement, respectively. During the three and nine months ended September 30, 2023, service revenue related to research activities performed in connection with the Vertex Research Service Agreement was not material.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

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+ Details