Akero Therapeutics (AKRO) 10-Q 8 Nov 24 2024 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2024	Oct. 31, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2024
Entity File Number	001-38944
Entity Registrant Name	Akero Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-5266573
Entity Address, Address Line One	601 Gateway Boulevard, Suite 350
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	487-6488
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	AKRO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		69,799,148
Entity Central Index Key	0001744659
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 316,065	$ 234,207
Short-term marketable securities	401,182	315,803
Prepaid expenses and other current assets	29,641	9,952
Total current assets	746,888	559,962
Long-term marketable securities	69,824	19,283
Property and equipment, net	15	18
Right of use asset	820	1,008
Total assets	817,547	580,271
Current liabilities:
Accounts payable	25,223	7,038
Accrued expenses and other current liabilities	18,068	12,090
Total current liabilities	43,291	19,128
Loan payable, noncurrent	35,123	24,964
Warrant liability	203	54
Operating lease liability, noncurrent	605	819
Total liabilities	79,222	44,965
Commitments and contingencies (Note 12)
Stockholders' equity:
Common stock, $0.0001 par value, 150,000,000 shares authorized as of September 30, 2024 and December 31, 2023; 69,614,587 and 55,754,445 shares issued and outstanding as of September 30, 2024 and December 31, 2023, respectively	7	6
Additional paid-in capital	1,492,347	1,109,126
Accumulated other comprehensive income	2,103	270
Accumulated deficit	(756,132)	(574,096)
Total stockholders' equity	738,325	535,306
Total liabilities and stockholders' equity	$ 817,547	$ 580,271

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Nov. 30, 2024	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized		150,000,000	150,000,000
Common stock, shares issued		69,614,587	55,754,445
Common stock, shares outstanding		69,614,587	55,754,445

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating expenses:
Research and development	$ 72,232	$ 38,634	$ 178,204	$ 88,406
General and administrative	9,471	7,981	29,194	22,591
Total operating expenses	81,703	46,615	207,398	110,997
Loss from operations	(81,703)	(46,615)	(207,398)	(110,997)
Interest expense	(1,246)	(888)	(3,468)	(2,202)
Interest and other income, net	10,244	7,844	28,830	16,626
Net loss	(72,705)	(39,659)	(182,036)	(96,573)
Net unrealized gain (loss) on marketable securities	2,364	(255)	1,833	(543)
Comprehensive loss	$ (70,341)	$ (39,914)	$ (180,203)	$ (97,116)
Net loss per share, basic	$ (1.05)	$ (0.71)	$ (2.76)	$ (1.87)
Net loss per share, diluted	$ (1.05)	$ (0.71)	$ (2.76)	$ (1.87)
Weighted-average number of shares used in computing net loss per common share, basic	69,442,136	55,613,120	65,982,798	51,506,766
Weighted-average number of shares used in computing net loss per common share, diluted	69,442,136	55,613,120	65,982,798	51,506,766

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	ATM Offering	Direct Offering	Follow on Offering	Common Stock	Common Stock ATM Offering	Common Stock Direct Offering	Common Stock Follow on Offering	Additional Paid-In-Capital	Additional Paid-In-Capital ATM Offering	Additional Paid-In-Capital Direct Offering	Additional Paid-In-Capital Follow on Offering	Accumulated Other Comprehensive Gain (Loss)	Accumulated Deficit
Balance at beginning at Dec. 31, 2022	$ 326,562				$ 5				$ 748,857				$ 37	$ (422,337)
Balance at beginning (in shares) at Dec. 31, 2022					46,865,206
Exercise of stock options	456								456
Exercise of stock options (in shares)					105,783
Common stock issued for Vested restricted stock units, Shares					8,067
Vested warrants issued pursuant to loan agreement	330								330
Stock-based compensation expense	4,844								4,844
Net unrealized gain (loss) on marketable securities	(16)												(16)
Net loss	(25,831)													(25,831)
Balance at ending at Mar. 31, 2023	306,345				$ 5				754,487				21	(448,168)
Balance at ending (in shares) at Mar. 31, 2023					46,979,056
Balance at beginning at Dec. 31, 2022	326,562				$ 5				748,857				37	(422,337)
Balance at beginning (in shares) at Dec. 31, 2022					46,865,206
Net unrealized gain (loss) on marketable securities	(543)
Net loss	(96,573)
Balance at ending at Sep. 30, 2023	$ 583,135				$ 6				1,102,545				(506)	(518,910)
Balance at ending (in shares) at Sep. 30, 2023	55,681,026
Balance at beginning at Dec. 31, 2022	$ 326,562				$ 5				748,857				37	(422,337)
Balance at beginning (in shares) at Dec. 31, 2022					46,865,206
Net loss	(151,759)
Balance at ending at Dec. 31, 2023	535,306				$ 6				1,109,126				270	(574,096)
Balance at ending (in shares) at Dec. 31, 2023					55,754,445
Balance at beginning at Mar. 31, 2023	306,345				$ 5				754,487				21	(448,168)
Balance at beginning (in shares) at Mar. 31, 2023					46,979,056
Exercise of stock options	1,556								1,556
Exercise of stock options (in shares)					306,510
Common stock issued for Vested restricted stock units, Shares					9,956
Issuance of common stock pursuant to ESPP purchases	313								313
Issuance of common stock pursuant to ESPP purchases (in shares)					7,885
Issuance of common stock, net of issuance costs		$ 123,824	$ 210,956				$ 1			$ 123,824	$ 210,955
Issuance of common stock (in shares)						3,006,052	5,238,500
Stock-based compensation expense	4,798								4,798
Net unrealized gain (loss) on marketable securities	(272)												(272)
Net loss	(31,083)													(31,083)
Balance at ending at Jun. 30, 2023	616,437				$ 6				1,095,933				(251)	(479,251)
Balance at ending (in shares) at Jun. 30, 2023					55,547,959
Exercise of stock options	$ 873								873
Exercise of stock options (in shares)	123,094
Common stock issued for Vested restricted stock units, Shares	9,973
Stock-based compensation expense	$ 5,739								5,739
Net unrealized gain (loss) on marketable securities	(255)												(255)
Net loss	(39,659)													(39,659)
Balance at ending at Sep. 30, 2023	$ 583,135				$ 6				1,102,545				(506)	(518,910)
Balance at ending (in shares) at Sep. 30, 2023	55,681,026
Balance at beginning at Dec. 31, 2023	$ 535,306				$ 6				1,109,126				270	(574,096)
Balance at beginning (in shares) at Dec. 31, 2023					55,754,445
Exercise of stock options	1,769								1,769
Exercise of stock options (in shares)					233,321
Common stock issued for Vested restricted stock units, Shares					10,663
Vested warrants issued pursuant to loan agreement	431								431
Issuance of common stock, net of issuance costs		$ 10,604		$ 344,438				$ 1		$ 10,604		$ 344,437
Issuance of common stock (in shares)						500,000		12,650,000
Stock-based compensation expense	7,398								7,398
Net unrealized gain (loss) on marketable securities	(349)												(349)
Net loss	(53,344)													(53,344)
Balance at ending at Mar. 31, 2024	846,253				$ 7				1,473,765				(79)	(627,440)
Balance at ending (in shares) at Mar. 31, 2024					69,148,429
Balance at beginning at Dec. 31, 2023	$ 535,306				$ 6				1,109,126				270	(574,096)
Balance at beginning (in shares) at Dec. 31, 2023					55,754,445
Exercise of stock options (in shares)	601,270
Net unrealized gain (loss) on marketable securities	$ 1,833
Net loss	(182,036)
Balance at ending at Sep. 30, 2024	738,325				$ 7				1,492,347				2,103	(756,132)
Balance at ending (in shares) at Sep. 30, 2024					69,614,587
Balance at beginning at Mar. 31, 2024	846,253				$ 7				1,473,765				(79)	(627,440)
Balance at beginning (in shares) at Mar. 31, 2024					69,148,429
Exercise of stock options	3								3
Exercise of stock options (in shares)					334
Common stock issued for Vested restricted stock units, Shares					40,661
Issuance of common stock pursuant to ESPP purchases	324								324
Issuance of common stock pursuant to ESPP purchases (in shares)					16,244
Stock-based compensation expense	7,656								7,656
Net unrealized gain (loss) on marketable securities	(182)												(182)
Net loss	(55,987)													(55,987)
Balance at ending at Jun. 30, 2024	798,067				$ 7				1,481,748				(261)	(683,427)
Balance at ending (in shares) at Jun. 30, 2024					69,205,668
Exercise of stock options	3,131								3,131
Exercise of stock options (in shares)					367,615
Common stock issued for Vested restricted stock units, Shares					41,304
Stock-based compensation expense	7,468								7,468
Net unrealized gain (loss) on marketable securities	2,364												2,364
Net loss	(72,705)													(72,705)
Balance at ending at Sep. 30, 2024	$ 738,325				$ 7				$ 1,492,347				$ 2,103	$ (756,132)
Balance at ending (in shares) at Sep. 30, 2024					69,614,587

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (182,036)	$ (96,573)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	22,522	15,381
Depreciation	3	27
Non-cash lease expense	188	174
Net amortization of premiums and discounts on short-term investments	(10,106)	(5,908)
Amortization of debt issuance costs and discount	433	328
Fair value change in warrant liability	526	118
Write-off of deferred offering costs		337
Unrealized foreign exchange gain and loss	67	(26)
Acquired in-process research and development expense	999
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(19,495)	(17,793)
Accounts payable	18,118	3,584
Accrued expenses and other current liabilities	5,955	3,782
Operating lease liability	(191)	(171)
Net cash used in operating activities	(163,017)	(96,740)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of short-term and long-term marketable securities	(436,316)	(374,909)
Proceeds from maturities of short-term marketable securities	312,335	138,500
Purchase of in-process research and development	(999)
Net cash used in investing activities	(124,980)	(236,409)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the exercise of stock options	4,903	2,817
Proceeds from the issuance of common stock pursuant to employee stock purchase plan purchases	324	313
Proceeds from the issuance of common stock in a follow-on public offering	344,839
Proceeds from the issuance of common stock pursuant to the ATM offering	10,604	124,212
Proceeds from the issuance of common stock pursuant to registered direct offering		211,217
Proceeds from loan payable	10,000	15,000
Payment of debt and equity issuance costs	(815)	(745)
Net cash provided by financing activities	369,855	352,814
Net increase in cash, cash equivalents and restricted cash	81,858	19,665
Cash, cash equivalents and restricted cash at the beginning of the period	234,207	249,881
Cash, cash equivalents and restricted cash at the end of the period	316,065	269,546
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	2,948	1,715
NON-CASH INVESTING AND FINANCING INFORMATION:
Change in net unrealizable gain (loss) on marketable securities	$ 1,833	$ (543)
Warrant liability costs reclassified to additional paid-in equity on vested warrants issued	431	330
Debt and equity issuance costs included in accounts payable and accrued expenses and other current liabilities	$ 15
Deferred offering costs reclassified to additional paid-in equity		$ 364
Stock options exercises included in other current assets		$ 67

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (72,705)	$ (55,987)	$ (53,344)	$ (39,659)	$ (31,083)	$ (25,831)	$ (182,036)	$ (96,573)	$ (151,759)	$ (112,033)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	The following table describes contracts, instructions or written plans for the sale or purchase of our securities adopted by certain officers during the three months ended September 30, 2024, each of which is intended to satisfy the affirmative defense conditions of Exchange Act Rule 10b5-1(c), referred to as Rule 10b5-1 trading plans. Name and Title Date and Action Taken Duration of Trading Arrangement Aggregate Number of Securities to be Sold or Purchased Timothy Rolph , Chief Scientific Officer Plan Adopted on August 12, 2024 365 days 225,119 Andrew Cheng , President and Chief Executive Officer Plan Adopted on August 16, 2024 356 days 360,000
Timothy Rolph
Trading Arrangements, by Individual
Name	Timothy Rolph
Title	Chief Scientific Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	August 12, 2024
Arrangement Duration	365 days
Aggregate Available	225,119
Andrew Cheng
Trading Arrangements, by Individual
Name	Andrew Cheng
Title	President and Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	August 16, 2024
Arrangement Duration	356 days
Aggregate Available	360,000

Nature of the business and basi

Nature of the business and basis of presentation	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the business and basis of presentation	1. Nature of the business and basis of presentation Akero Therapeutics, Inc., together with its subsidiaries, (“Akero” or the “Company”) is a clinical-stage company dedicated to developing transformational treatments for patients with serious metabolic diseases marked by high unmet medical need, including metabolic dysfunction-associated steatohepatitis, or MASH, formerly known as non-alcoholic steatohepatitis, or NASH. MASH is a severe form of metabolic dysfunction-associated steatotic liver disease, or MASLD, formerly known as nonalcoholic fatty liver disease, or NAFLD, characterized by inflammation and fibrosis in the liver that can progress to cirrhosis, liver failure, cancer and death. The company's lead product candidate, efruxifermin, or EFX, is an analog of fibroblast growth factor 21, or FGF21, which is an endogenously expressed hormone that protects against cellular stress and regulates metabolism of lipids, carbohydrates and proteins throughout the body. The company has initiated a Phase 3 program called SYNCHRONY, which is comprised of three ongoing clinical trials ( Outcomes , Histology , and Real-World ) designed to support applications for marketing approval for patients with pre-cirrhotic MASH (F2-F3) and compensated cirrhosis (F4) due to MASH . The SYNCHRONY program builds on two biopsy-based Phase 2b studies in corresponding patient populations, with a combined total of over 300 patients treated for up to 96 weeks. Based on statistically significant fibrosis regression and MASH resolution among patients with biopsy-confirmed pre-cirrhotic MASH, as well as a trend toward fibrosis improvement and statistically significant MASH resolution among patients with cirrhosis due to MASH, we believe EFX has the potential, if approved, to be an important medicine for treating MASH. The Company is subject to risks and uncertainties common to mid-stage companies in the biotechnology industry, including, but not limited to, completion and success of clinical testing, preparation for a potential commercial launch of EFX, if approved, development by competitors of new technological innovations, compliance with governmental regulations, dependence on key personnel and protection of proprietary technology and the ability to secure additional capital to fund operations. EFX will require extensive clinical testing prior to regulatory approval and commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Basis of presentation The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company after elimination of all intercompany accounts and transactions. All adjustments necessary for the fair presentation of the Company’s condensed consolidated financial statements for the periods presented have been reflected. Liquidity In accordance with Accounting Standards Update (“ASU”) No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) , the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. Since its inception, the Company has raised $ 1,427,900 in capital funds, including $ 105,800 in proceeds from its initial public offering (“IPO”) in June 2019, $ 1,196,600 in proceeds from the sales of common stock in equity offerings between 2020 and 2024, which includes a $ 25,000 equity investment from Pfizer, Inc. in 2022, $ 90,500 in proceeds from the sale of redeemable convertible preferred stock and $ 35,000 in venture debt borrowings. The Company has incurred recurring losses since its inception, including net losses of $ 182,036 and $ 96,573 for the nine months ended September 30, 2024 and 2023, respectively, and net losses of $ 151,759 and $ 112,033 for the years ended December 31, 2023 and 2022, respectively. In addition, as of September 30, 2024, the Company had an accumulated deficit of $ 756,132 . The Company expects to continue to generate operating losses for the foreseeable future. As of November 8, 2024, the issuance date of these condensed consolidated financial statements, the Company expects that its existing cash, cash equivalents and short- and long-term marketable securities of $ 787,071 as of September 30, 2024, will be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months from the issuance date of these condensed consolidated financial statements. The Company expects that it will require additional funding to complete the clinical development of EFX, commercialize EFX, if it receives regulatory approval, and pursue in-licenses or acquisitions of other product candidates. If the Company is unable to obtain funding, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.

Summary of significant accounti

Summary of significant accounting policies	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Summary of significant accounting policies	2. Summary of significant accounting policies Unaudited interim financial statements The accompanying unaudited condensed consolidated financial statements have been prepared by the Company in accordance with GAAP for interim financial reporting and as required by Regulation S-X, Rule 10-01. The unaudited condensed consolidated financial statements have been prepared on the same basis as the Company’s audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the Company’s condensed consolidated balance sheet as of September 30, 2024, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2024 and 2023, the condensed consolidated statement of stockholders’ equity (deficit) for the three months ended March 31, 2024 and 2023, three months ended June 30, 2024 and 2023 and the three months ended September 30, 2024 and 2023 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2024 and 2023. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2024 and 2023 are unaudited. The results for the three and nine months ended September 30, 2024 are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. Operating segment information Operating segments are defined as components of an enterprise for which separate and discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company has one operating segment. The Company’s focus is the research and development of treatments for patients with serious metabolic diseases marked by high unmet medical need, including MASH. The Company’s chief operating decision maker, its chief executive officer, manages the Company’s operations on a consolidated basis for the purpose of allocating resources. Use of estimates The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the condensed consolidated financial statements and accompanying notes. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the recognition of research and development expenses, stock-based compensation expense, warrant liabilities and the valuation allowance for deferred tax assets. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. Cash and cash equivalents The Company considers all highly liquid investments with original maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts. The fair value of cash equivalents approximate their carrying values due to the short-term nature of such financial instruments. Short and long-term marketable securities The Company invests in short-term and long-term marketable securities, primarily money market funds, commercial paper, U.S. treasury securities and corporate debt securities. The Company continually evaluates the credit ratings of its investment portfolio and underlying securities. The Company invests in accordance with its investment policy and invests at the date of purchase in securities with high ratings from top rating agencies. The Company classifies its short- and long-term marketable securities as available-for-sale securities and reports them at fair value in short-term and long-term marketable securities on the condensed consolidated balance sheets with related unrealized gains and losses included within accumulated other comprehensive gain (loss) on the condensed consolidated balance sheets. The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in other income on the condensed consolidated statements of operations and comprehensive loss. When the fair value is below the amortized cost of a marketable security, the Company reviews and determines whether the impairment is due to credit-related factors or noncredit-related factors. The credit-related impairment amount is recognized in other income on the condensed consolidated statements of operations and comprehensive loss, with a corresponding allowance for credit losses account in the condensed consolidated balance sheet. Subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in the condensed consolidated statements of operations. There were no credit losses recorded during the periods ended September 30, 2024 and 2023. Concentrations of credit risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents and short- and long-term marketable securities. Periodically, the Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company deposits its cash investments in financial institutions that it believes have high credit quality and has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. At September 30, 2024, all of the Company's cash, cash equivalents and short and long-term investments were held at three accredited financial institutions. Leases The Company determines whether an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether the Company has the right to control the identified asset. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Lease liabilities are recognized at the lease commencement date based on the present value of future lease payments over the lease term. ROU assets are based on the measurement of the lease liability and are further adjusted by any lease payments made prior to or on lease commencement, lease incentives received and initial direct costs incurred, as applicable. The Company has elected to not recognize leases with a lease term of one year or less on its balance sheet. Operating lease costs included in the measurement of the lease are recognized on a straight-line basis over the lease term. Variable lease costs are expensed as incurred as an operating expense. The Company determines the lease classification and the present value of future lease payments at the time of the lease commencement using an incremental borrowing rate that it estimates based upon the Company’s credit risk and term of the lease. The interest rate implicit in lease contracts has not historically been readily determinable and the Company must therefore use the appropriate incremental borrowing rate to measure its leases. To estimate the incremental borrowing rate, a credit rating applicable to the Company is estimated using a synthetic credit rating analysis since the Company does not currently have a rating agency-based credit rating. Research and development costs Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred to discover, research and develop drug candidates, including personnel expenses, stock-based compensation expense, third-party license fees and external costs including fees paid to consultants, contract manufacturing organizations, or CMOs, and clinical research organizations, or CROs, in connection with drug product manufacturing, nonclinical studies and clinical trials, and other related clinical trial fees, such as for investigator grants, patient screening, laboratory work, clinical trial database management, clinical trial material management and statistical compilation and analysis. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered or the services rendered. Foreign currency transaction gains and losses related to the purchase of contract manufacturing services are included as a component of research and development expense. Costs incurred in obtaining technology licenses are charged immediately to research and development expense if the technology licensed has not reached technological feasibility and has no alternative future uses. Accrued and prepaid research and development expenses The Company has entered into various research and development and other agreements with commercial firms, researchers and others for provisions of goods and services. These agreements are generally cancelable, and the related costs are recorded as research and development expenses as incurred. The Company makes estimates of accrued and prepaid research and development expenses as of each balance sheet date based on facts and circumstances known at that time. When evaluating the adequacy of the accrued liabilities and the appropriateness of the prepaid expenses, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued and prepaid balances at the end of any reporting period. Actual results could differ materially from the Company's estimates . Stock-based compensation The Company makes stock-based awards from its stock compensation plans (see Note 8). The Company measures all stock option awards granted to employees and nonemployees based on the fair value on the date of the grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis. The Company accounts for forfeitures as they occur. The Company recognizes stock-based compensation expense for awards that contain performance-based conditions using the accelerated attribution method when management determines it is probable that the performance condition will be satisfied. The Company measures restricted stock unit awards based on the market closing price of the Company's common stock on the grant date. Stock-based compensation expense for these awards is recognized on a straight-line basis over the requisite service period, generally four years. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model, which requires inputs based on certain subjective assumptions, including the expected stock price volatility, the expected term of the option, the risk-free interest rate for a period that approximates the expected term of the option, and the Company's expected dividend yield. The Company currently estimates its share price volatility using a combined weighting of the historical volatility of publicly traded peer companies and the volatility of its traded share price and expects to continue to do so until mid-2025. The expected term of the Company's stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends on common stock and the expectation that it will not pay any cash dividends in the foreseeable future. Compensation expense for purchases under the Employee Stock Purchase Plan is recognized based on the fair value of the common stock estimated based on the closing price of our common stock as reported on the date of offering, less the purchase discount percentage provided for in the plan. The Company classifies stock-based compensation expense in its condensed consolidated statement of operations and comprehensive loss in the same manner in which the award recipient's payroll costs are classified or in which the award recipient's service payments are classified. Loan payable Loan Payable represents borrowings under the Loan and Security Agreement, dated June 15, 2022 (“Loan Agreement”) with Hercules Capital, Inc. (“Hercules”), subsequently amended on June 7, 2023 and February 28, 2024, which the Company has accounted for as a debt financing arrangement. Interest expense is accrued using the effective interest rate method over the estimated period the loan will be repaid. Loan issuance costs have been recorded as a debt discount in the condensed consolidated balance sheets and are being amortized and recorded as interest expense throughout the life of the Loan Agreement using the effective interest rate method. The Company considered whether there were any embedded features in the Loan Agreement that require bifurcation and separate accounting as derivative financial instruments pursuant to Accounting Standards Codification (“ASC”) Topic 815, Derivatives and Hedging . The Loan Agreement was amended on February 28, 2024. The Company accounted for the amendment as a debt modification arrangement pursuant to ASC Topic 470, Debt—Modifications and Extinguishments. Warrant liabilities The Company accounts for warrants anticipated to be issued in the future under the Loan Agreement as liabilities and measures them at fair value using the Black-Scholes valuation model. The warrants are subject to remeasurement at each prospective balance sheet date, with any changes in the fair value recorded in the condensed consolidated statements of operations. Comprehensive loss Comprehensive loss includes net loss as well as other changes in stockholders' equity (deficit) that result from transactions and economic events other than those with stockholders. The Company’s comprehensive loss is comprised of net loss and changes in unrealized gains and losses on its short- and long-term marketable securities . Recently issued accounting standards not yet adopted In November 2023, the FASB, issued ASU No. 2023-07 , Segment Reporting (Topic 280), Improvements to Reportable Segment Disclosures, to improve reportable segment disclosure requirements. The amendment introduced new requirements to disclose significant segment expenses regularly provided to the chief operating decision maker (“CODM”) and extend certain annual disclosures to interim periods. Entities with a single reportable segment must apply ASC 280 in its entirety, are permitted to report more than one measure of segment profit or loss under certain conditions and are required to disclose the title and position of the CODM. ASU No. 2023-07 is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the effect this standard will have on its condensed consolidated financial statements and related disclosures. In December 2023, the Financial Accounting Standards Board (“FASB”), issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740), Improvements to Income Tax Disclosures, to enhance the transparency and decision usefulness of income tax disclosures. The enhancement will provide information to better assess how an entity’s operations and related tax risks and tax planning and operational opportunities affect its tax rate and prospects for future cash flows. Investors currently rely on the rate reconciliation table and other disclosures, including total income taxes paid, to evaluate income tax risks and opportunities. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and early adoption is permitted. The Company is currently evaluating the impact ASU No. 2023-09 will have on its condensed consolidated financial statements and related disclosures.

Fair value measurements

Fair value measurements	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair value measurements	3. Fair value measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are no t active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The following is a summary of the Company's financial assets and liabilities measured at fair value on a recurring basis as of September 30, 2024 and December 31, 2023: September 30, 2024 Total Level 1 Level 2 Level 3 Money market funds $ 303,324 $ 303,324 $ — $ — U.S. Treasury securities 248,440 248,440 — — U.S. Government agency securities 70,258 — 70,258 — Commercial paper 59,078 — 59,078 — Corporate debt securities 93,230 — 93,230 — Total assets $ 774,330 $ 551,764 $ 222,566 $ — Warrant liabilities $ 203 $ — $ — $ 203 Total liabilities $ 203 $ — $ — $ 203 December 31, 2023 Total Level 1 Level 2 Level 3 Money market funds $ 206,879 $ 206,879 $ — $ — U.S. Treasury securities 117,307 117,307 — — U.S. Government agency securities 133,297 — 133,297 — Commercial paper 68,708 — 68,708 — Corporate debt securities 15,774 — 15,774 — Total assets $ 541,965 $ 324,186 $ 217,779 $ — Warrant liabilities $ 54 $ — $ — $ 54 Total liabilities $ 54 $ — $ — $ 54 Level 2 assets were valued using quoted prices in active markets for similar securities. The carrying values of the Company’s prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. During the nine months ended September 30, 2024 and the twelve months ended December 31, 2023, there were no transfers between Level 1, Level 2 and Level 3. The Loan Payable is classified as a Level 3 liability. As of September 30, 2024, the carrying value of the Loan Payable approximates its fair value. The Company estimated the fair value of the warrant liabilities using the Black-Scholes model based on key assumption and inputs (see Note 6). The Company utilizes a probability assessment to estimate the likelihood of vesting for the remaining Loan Agreement warrants and allocated the probability of occurrence percentage to the fair values calculated.

Short and long-term marketable

Short and long-term marketable securities	9 Months Ended
	Sep. 30, 2024
Short and long-term marketable securities
Short and long-term marketable securities	4. Short and long-term marketable securities The following is a summary of short-term and long-term marketable securities as of September 30, 2024 and December 31, 2023 : September 30, 2024 Amortized cost Gross unrealized gains Gross unrealized losses Credit losses Fair value Money market funds $ 303,324 $ — $ — $ — $ 303,324 U.S. Treasury securities 246,981 1,459 — — 248,440 U.S. Government agency securities 70,042 216 — — 70,258 Commercial paper 58,954 124 — — 59,078 Corporate debt securities 92,926 304 — — 93,230 $ 772,227 $ 2,103 $ — $ — $ 774,330 Cash equivalents $ 303,324 Short-term marketable securities 401,182 Long-term marketable securities 69,824 $ 774,330 December 31, 2023 Amortized cost Gross unrealized gains Gross unrealized losses Credit losses Fair value Money market funds $ 206,879 $ — $ — $ — $ 206,879 U.S. Treasury securities 117,058 255 ( 6 ) — 117,307 U.S. Government agency securities 133,279 78 ( 60 ) — 133,297 Commercial paper 68,707 10 ( 9 ) — 68,708 Corporate debt securities 15,773 1 — — 15,774 $ 541,696 $ 344 $ ( 75 ) $ — $ 541,965 Cash equivalents $ 206,879 Short-term marketable securities 315,803 Long-term marketable securities 19,283 $ 541,965 The following table presents the contractual maturities of the Company's short-term and long-term marketable securities as of September 30, 2024 and December 31, 2023. September 30, 2024 December 31, 2023 Due within one year $ 401,182 $ 315,803 Due after one year through two years 69,824 19,283 Total $ 471,006 $ 335,086

Accrued expenses and other curr

Accrued expenses and other current liabilities	9 Months Ended
	Sep. 30, 2024
Accrued expenses and other current liabilities
Accrued expenses and other current liabilities	5. Accrued expenses and other current liabilities The following is a summary of accrued expenses and other current liabilities as of September 30, 2024 and December 31, 2023 : September 30, 2024 December 31, 2023 Accrued external research and development expenses $ 12,789 $ 10,041 Accrued employee compensation and benefits 4,369 1,296 Accrued legal and professional fees 279 231 Short-term lease liability and other 631 522 $ 18,068 $ 12,090

Loan Payable and Warrant Liabil

Loan Payable and Warrant Liability	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Loan Payable and Warrant Liability	6. Loan Payable and Warrant Liability On June 15, 2022, the Company entered into the Loan Agreement with Hercules, which was subsequently amended on June 7, 2023 and February 28, 2024, for an aggregate principal amount of $ 150,000 (“Term Loan”). Pursuant to the amended Loan Agreement, the Term Loan is available to the Company in five tranches, subject to certain terms and conditions. Under the terms of the Loan Agreement, the Company received $ 10,000 upon closing, $ 15,000 was borrowed in March 2023 and an additional $ 10,000 was borrowed in connection with the second amendment on February 28, 2024 (the “Tranche I and Tranche II Commitments”). At the sole discretion of the Company, $ 30,000 is available to be drawn from June 15, 2024 through June 15, 2025 (“Tranche III Commitment”). Also at the sole discretion of the Company, an additional $ 35,000 is available to be drawn at the earlier of the full draw of Tranche III or June 15, 2025 through June 15, 2026 (“Tranche IV Commitment”). An additional $ 50,000 may become available to the Company prior to January 1, 2026, subject to Hercules' approval (“Tranche V Commitment”). The Term Loan will mature on March 1, 2027 (the “Maturity Date”). The Term Loan bears interest at a variable annual rate equal to the greater of (a) 7.65 % and (b) the Prime Rate (as reported in the Wall Street Journal) plus 3.65 % (the “Interest Rate”). The Company makes payments of interest only until January 1, 2026 (the “interest-only period”). After the interest-only period, the principal balance and related interest are required to be repaid in equal monthly installments and continuing until the Maturity Date. The Loan Agreement contains customary closing fees, events of default, and representations, warranties and covenants, including a financial covenant requiring the Company to maintain a minimum cash balance in relation to the outstanding principal balance of the Term Loan. The Loan Agreement provides for a prepayment charge equal to 1 % of the outstanding principal balance of the Term Loan. In addition, the Loan Agreement provides for an End of Term Charge equal to the greater of 5.85 % of the outstanding principal balance, or $ 2,048 , which is recognized as a debt discount and is being accreted into the amortization of debt issuance costs and discount using the effective interest rate method over the term of the loan payable. The Company was in compliance with all covenants of the Loan Agreement as of September 30, 2024. The Loan Agreement requires the Company to issue warrants to Hercules to purchase shares of the Company’s common stock, par value $ 0.0001 per share (“common stock”). The amount of shares that may be purchased for the warrants will not exceed 1.5 % multiplied by the greater of Tranche I and the aggregate original amount of the term loan advances, divided by the exercise price of the warrants. Upon closing, the Company issued to Hercules warrants to purchase 36,718 shares of Company’s common stock and recognized them at their relative fair value of $ 227 as of the date of issuance in the shareholders equity category of the balance sheet. In accordance with ASC 815-40, additional warrants to purchase shares of the Company’s common stock that the Company is contingently required to issue are recognized at their relative fair value in the noncurrent liabilities category of the balance sheet, given the variable settlement amount of the warrant shares. The fair value of the equity and liability classified warrants are collectively recognized as a debt discount and are being accreted into the amortization of debt issuance costs and discount using the effective interest rate method over the term of the loan. The Company reassesses the fair value of the warrant liability at the end of each reporting period. On March 10, 2023, the Company issued warrants to purchase 9,180 shares of the Company's common stock in connection with the $ 15,000 borrowed from Hercules on that date, and the fair value associated with these warrants of $ 330 was reclassified from warrant liability to additional paid in capital. On February 28, 2024, the Company issued warrants to purchase 18,359 shares of the Company's common stock in connection with the $ 10,000 borrowed from Hercules on that date, and the fair value associated with these warrants of $ 431 was reclassified from warrant liability to additional paid in capital. As of September 30, 2024, the Company is contingently liable to issue warrants to purchase up to an additional 211,137 shares of common stock under the Loan Agreement, in connection with future borrowings as they may occur. Future principal debt payments on the currently outstanding loan payable as of September 30, 2024 and December 31, 2023 are as follows (in thousands): September 30, 2024 December 31, 2023 2024 $ — $ — 2025 — 7,343 2026 27,655 16,118 2027 7,345 1,539 Total principal outstanding 35,000 25,000 End of term charge 2,048 1,463 Total principal outstanding and end of term charge 37,048 26,463 Unamortized discount and issuance costs ( 1,925 ) ( 1,499 ) Loan Payable $ 35,123 $ 24,964 Loan Payable - current $ — $ — Loan Payable - noncurrent 35,123 24,964 Loan Payable $ 35,123 $ 24,964 The Company estimated the fair value of the warrant liability as of September 30, 2024 using probability assumptions of achieving the future milestones and using the Black-Scholes model based on the following key assumptions: Nine Months Ended September 30, 2024 2023 Expected term (in years) 4.7 5.7 Expected volatility 88.41 % 79.55 % Risk-free interest rate 3.58 % 4.60 % Expected dividend yield 0.00 % 0.00 %

Stockholder's equity (deficit)

Stockholder's equity (deficit)	9 Months Ended
	Sep. 30, 2024
Stockholders' Equity Note [Abstract]
Stockholder's equity (deficit)	7. Stockholder’s equity (deficit) Common stock As of September 30, 2024 and December 31, 2023, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue 150,000,000 shares of $ 0.0001 par value common stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. The holders of common stock, voting exclusively and as a separate class, have the exclusive right to vote for the election of directors of the Company. Common stockholders are entitled to receive dividends, as may be declared by the board of directors. Through September 30, 2024, no cash dividends had been declared or paid. On June 24, 2019, the Company completed its IPO at which time the Company issued 6,612,500 shares of common stock, including the exercise in full by the underwriters of their option to purchase up to 862,500 additional shares of common stock, at a public offering price of $ 16.00 per share. The Company received $ 98,394 , net of underwriting discounts and commissions, but before deducting offering costs paid by the Company, which were $ 2,942 . Upon the closing of the IPO, all outstanding shares of convertible preferred stock converted into 21,056,136 shares of common stock. On July 10, 2020, the Company completed a follow-on public offering at which time the Company issued 6,012,390 shares of common stock, including the exercise in full by the underwriters of their option to purchase up to 784,224 additional shares of common stock, at a public offering price of $ 36.00 per share. The Company received $ 203,460 net of underwriting discounts and commissions, but before deducting offering costs paid by the Company. In March 2023, the Company entered into a sales agreement with Jefferies LLC (the “Sales Agreement”) activating an At-The-Market (“ATM”) facility. Pursuant to the Sales Agreement, the Company filed a prospectus supplement on March 17, 2023, under which the Company may offer and sell shares of common stock, having an aggregate value of up to $ 200,000 . In April and May 2023, the Company sold 3,006,052 shares of common stock under the Sales Agreement, at an average price of $ 42.38 per share, and received net proceeds of $ 123,824 , after deducting sales agent commissions and issuance costs of approximately $ 3,578 . In February 2024, the Company sold an additional 500,000 shares of common stock under the Sales Agreement, at an average price of $ 21.75 per share, and received net proceeds of $ 10,604 , after deducting sales agent commissions and issuance costs of approximately $ 271 . On June 15, 2022, the Company entered into a securities purchase agreement for the sale of 2,525,252 shares of the Company's common stock to Pfizer Inc. at $ 9.90 per share in a registered direct offering conducted without an underwriter or placement agent and pursuant to the Company’s effective shelf registration statement on Form S-3ASR and a related prospectus supplement filed with the U.S. Securities and Exchange Commission (“SEC”). The offering closed on June 17, 2022 for net proceeds of $ 24,647 , after deducting offering costs paid by the Company. On September 19, 2022, the Company completed a follow-on public offering at which time the Company issued 8,846,154 shares of common stock, including the exercise in full by the underwriters of their option to purchase up to 1,153,846 additional shares of common stock, at a public offering price of $ 26.00 per share. The Company received $ 216,200 net of underwriting discounts and commissions of $ 13,800 , but before deducting offering costs incurred by the Company. On May 16, 2023, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC, (“Jefferies”), as a representative of the several underwriters, pursuant to which the Company agreed to issue and sell 5,238,500 shares of the Company's common stock at $ 42.00 per share in a registered direct offering pursuant to the Company’s effective shelf registration statement on Form S-3ASR and a related prospectus supplement filed with the SEC. The offering closed on May 16, 2023. The Company received net proceeds of $ 210,956 , after deducting underwriters commissions and offering costs incurred by the Company of approximately $ 9,061 . On March 8, 2024, the Company completed a follow-on public offering at which time the Company issued 12,650,000 shares of common stock, including the exercise in full by the underwriters of their option to purchase up to 1,650,000 additional shares of common stock, at a public offering price of $ 29.00 per share. The Company received $ 344,838 net of underwriting discounts and commissions of $ 22,011 , but before deducting offering costs incurred by the Company of approximately $ 401 . On May 10, 2024, the Company entered into an amendment to the Sales Agreement (“Amended Sales Agreement”) to increase the aggregate offering price of the shares of the Company's common stock by an additional $ 200,000 . In accordance with the terms of the Amended Sales Agreement, the Company may now offer and sell shares of its common stock having an aggregate offering price of up to $ 261,723 from time to time. As of September 30, 2024 and December 31, 2023, there were 69,614,587 and 55,754,445 shares of common stock issued and outstanding, respectively. The following shares of common stock were reserved for issuance as follows: September 30, 2024 December 31, 2023 Options outstanding under the 2018 Stock Option and Grant Plan 679,016 1,114,189 Options outstanding under the 2019 Stock Option and Incentive Plan 6,617,378 5,785,788 Unvested restricted stock units outstanding under the 2019 Stock Option and Incentive Plan 536,717 371,952 Warrants to purchase common stock associated with Loan Agreement 64,257 45,898 Options available for future grant 2,892,453 1,917,356 Warrants available for future grant 211,137 137,700 Common stock available for ATM program 11,722,981 2,708,234 2019 Employee Stock Purchase Plan 1,980,783 1,586,224 24,704,722 13,667,341 Undesignated preferred stock The Company’s fourth amended and restated certificate of incorporation authorizes the Company to issue up to 10,000,000 shares of undesignated preferred stock, par value $ 0.0001 per share. There were no undesignated preferred shares issued or outstanding as of September 30, 2024. Warrants Associated with Loan Agreement In connection with the Loan Agreement with Hercules (see Note 6), the Company is obligated to issue warrants to purchase shares of the Company’s common stock. The amount of shares that may be purchased for the warrants will not exceed 1.5 % multiplied by the greater of Tranche I and the aggregate original amount of the term loan advances, divided by the exercise price of the warrants. Upon execution of the Loan Agreement on June 15, 2022, the Company issued warrants to purchase 36,718 shares of the Company’s common stock, which have been recorded at their relative fair value at the time of issuance within shareholder's equity. The Company issued warrants to purchase an additional 9,180 shares of the Company’s common stock to Hercules in connection with the additional $ 15,000 borrowing on March 10, 2023 and warrants to purchase 18,359 shares of the Company’s common stock to Hercules in connection with the additional $ 10,000 borrowing on February 28, 2024.

Stock-based awards

Stock-based awards	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-based awards	8. Stock-based awards 2018 Stock option and grant plan The Company’s 2018 Stock Option and Grant Plan (the “2018 Plan”) provided for the Company to grant incentive stock options or nonqualified stock options, restricted stock awards and other stock-based awards to employees, directors and consultants of the Company. The 2018 Plan was administered by the board of directors or, at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions were determined at the discretion of the board of directors, or its committee if so delegated. The total number of shares of common stock that could have been issued under the 2018 Plan was 3,071,960 shares, of which 107,635 shares remained available for grant on June 18, 2019, the date that the Company’s 2019 Stock Option and Incentive Plan (the “2019 Plan”) became effective. Upon the effectiveness of the 2019 Plan, the 107,635 remaining shares available under the 2018 Plan were transferred and became available for issuance under the 2019 Plan. Shares of common stock underlying outstanding awards under the 2018 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 common stock available for issuance under the 2019 Plan. 2019 Stock option and incentive plan The 2019 Plan was adopted and approved by the Company’s board of directors in May 2019 and by the Company’s stockholders in June 2019. The 2019 Plan became effective on June 18, 2019 and replaced the Company’s 2018 Plan on that date. The 2019 Plan allows the board of directors or the compensation committee of the board of directors to make equity-based incentive awards to the Company’s officers, employees, directors or other key persons (including consultants). The number of shares initially reserved for issuance under the 2019 Plan was 2,572,457 , which included the 107,635 shares transferred from the 2018 Plan, and shall be cumulatively increased on each January 1 by 4 % of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s board of directors or compensation committee of the board of directors. The 2019 Plan was increased by 1,874,608 shares on January 1, 2023 and by 2,230,177 shares on January 1, 2024. The 2019 Plan is administered by the board of directors or, at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or its committee if so delegated, except that the exercise price per share of stock options may not be less than 100 % of the fair market value of the share of common stock on the date of grant and the term of stock option may not be greater than ten years . All incentive options granted to any person possessing more than 10% of the total combined voting power of all classes of shares may not have an exercise price of less than 110 % of the fair market value of the common stock on the grant date. Stock options granted to employees, officers, members of the board of directors and consultants will typically vest over a four-year period. Shares that are expired, terminated, surrendered or canceled under the 2019 Plan without having been fully exercised will be available for future awards. 2019 Employee stock purchase plan The 2019 Employee Stock Purchase Plan (the “2019 ESPP”) was adopted and approved by the Company’s board of directors in May 2019 and by the Company’s stockholders in June 2019. The 2019 ESPP became effective on June 18, 2019, at which time 273,869 shares were reserved for issuance. The 2019 ESPP provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2020 and each January 1 through January 1, 2029, by the least of (i) 1 % of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31, (ii) 410,803 shares or (iii) such number of shares as determined by the compensation committee. The 2019 ESPP was increased by 410,803 shares on January 1, 2023 and by 410,803 shares on January 1, 2024. Stock option valuation The assumptions that the Company used to determine the grant-date fair value of stock options granted to employees, directors and consultants as follows, presented on a weighted average basis: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Expected term (in years) 5.96 5.85 5.93 5.88 Expected volatility 88.06 % 79.75 % 86.38 % 78.37 % Weighted average risk-free interest rate 4.41 % 4.18 % 4.30 % 3.91 % Expected dividend yield 0.00 % 0.00 % 0.00 % 0.00 % Stock options The following table summarizes the Company’s stock option activity since December 31, 2023: Weighted- Weighted- Average Average Aggregate Exercise Remaining Intrinsic Number Price per Contractual Value of Options Share Term (years) (000's) Balance outstanding, December 31, 2023 6,899,977 $ 22.35 7.67 $ 35,133 Options granted 1,018,350 $ 22.31 Options exercised ( 601,270 ) $ 8.15 Options cancelled ( 20,663 ) $ 39.16 Balance outstanding, September 30, 2024 7,296,394 $ 23.47 7.37 $ 56,484 Vested and expected to vest, September 30, 2024 7,296,394 $ 23.47 7.37 $ 56,484 Exercisable, September 30, 2024 4,447,229 $ 22.23 6.50 $ 38,146 The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The weighted average grant-date fair value per share of stock options granted during the three months ended September 30, 2024 and 2023 was $ 17.56 and $ 46.01 , respectively. Additionally, the weighted average grant-date fair value per share of stock options granted during the nine months ended September 30, 2024 and 2023 was $ 16.54 and $ 47.45 , respectively. Restricted Stock Units The 2019 Plan allows for the grants of Restricted Stock Units (“RSUs”). Generally, the RSUs are subject to a four-year vesting period, vesting in equal quarterly or semi-annual installments over the vesting period. The following table summarizes the Company’s RSUs activity since December 31, 2023: Weighted- Weighted- Average Average Aggregate Grant Date Remaining Intrinsic Underlying Fair Value per Contractual Value Shares Share Term (years) (000's) Balance outstanding, December 31, 2023 371,952 $ 28.53 1.98 $ 8,685 Granted 261,288 $ 23.46 Vested ( 92,628 ) $ 29.47 Cancelled or forfeited ( 3,895 ) $ 23.48 Balance outstanding, September 30, 2024 536,717 $ 25.94 1.63 $ 15,398 The aggregate intrinsic value of RSUs is calculated based of the fair value of the Company’s common stock and the outstanding RSUs. The weighted average grant-date fair value per share of RSUs granted during the three months ended September 30, 2024 and 2023 was $ 23.16 and $ 44.52 , respectively. Additionally, the weighted average grant-date fair value per share of RSUs granted during the nine months ended September 30, 2024 and 2023 was $ 23.46 and $ 48.17 , respectively. Stock-based compensation The following table summarizes the Company’s stock-based compensation expense during the three and nine months ended September 30, 2024 and 2023: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Classified within research and development expense $ 2,903 $ 1,986 $ 8,487 $ 5,485 Classified within general and administrative expense 4,565 3,753 14,035 9,896 Total stock-based compensation expense $ 7,468 $ 5,739 $ 22,522 $ 15,381 As of September 30, 2024, total unrecognized compensation cost related to unvested stock options and RSUs was $ 48,430 and $ 12,979 , respectively. These unvested stock options and RSUs are expected to be recognized over a weighted average period of 2.53 years and 3.06 years, respectively.

Amgen license agreement

Amgen license agreement	9 Months Ended
	Sep. 30, 2024
Amgen license agreement
Amgen license agreement	9. Amgen license agreement In June 2018, the Company entered into a license agreement (the “Amgen Agreement”) with Amgen, Inc. (“Amgen”) pursuant to which the Company was granted an exclusive license to certain patents and intellectual property related to a long-acting FGF21 analog in order to commercially develop, manufacture, use and distribute FGF21 as a treatment for MASH and other serious metabolic diseases. The Amgen Agreement provides the Company with exclusive global rights to the licensed products and the right to grant sublicenses that cover EFX to third parties. In exchange for these rights, the Company made an upfront payment of $ 5,000 and issued 2,653,333 shares of Series A Preferred Stock with a fair value of $ 1,353 to Amgen. Amgen was also entitled to maintain a 10 % ownership interest of the outstanding shares of the Company’s common stock, on a fully diluted and converted basis, through the second closing of the Company’s Series A Preferred Stock financing. In November 2018, in connection with the second closing of the Company’s Series A Preferred Stock financing, the Company issued 3,205,128 shares of Series A Preferred Stock to Amgen for a total value of $ 7,404 , satisfying its anti-dilution obligation under the Amgen Agreement. Under the Amgen Agreement, the Company made a milestone payment in the third quarter of 2019 of $ 2,500 in connection with dosing the first patient in the BALANCED study, a second milestone payment of $ 7,500 was paid in December 2023 with dosing the first patient in our Phase 3 SYNCHRONY program, and is obligated to pay Amgen up to $ 30,000 in connection with marketing approvals, and aggregate milestone payments of up to $ 75,000 upon the achievement of specified commercial milestones for all products licensed under the Amgen Agreement. Under the Amgen Agreement, the Company is obligated to pay Amgen tiered royalties ranging from a low to high single-digit percentages on annual net sales of the licensed products, beginning on the first commercial sale of such licensed products in each country and expiring on a country-by-country basis on the latest of (i) the expiration of the last valid patent claim covering such licensed products in such country, (ii) the loss of regulatory exclusivity in such country, and (iii) ten years after the first commercial sale of such licensed product in such country. The royalty payments are subject to reduction under specified conditions set forth in the Amgen Agreement. The Company is solely responsible for all development, manufacturing, and commercial activities and costs of the licensed products, including clinical studies or other tests necessary to support the use of a licensed product. The Company is also responsible for costs related to the filing, prosecution and maintenance of the licensed patent rights. The Amgen Agreement will remain in effect until the expiration of the royalty term in all countries for all licensed products. The Amgen Agreement may be terminated by either party with at least 90 days' notice in the event of material breach by the other party that remains uncured for 90 days, by either party for insolvency or bankruptcy of the other party and immediately by Amgen if the Company challenges the licensed patents. The Company may also terminate the Amgen Agreement with 90 days' written notice for discretionary reasons such as scientific, technical, regulatory or commercial issues, as defined in the Amgen Agreement. During the three and nine months ended September 30, 2024 and 2023, the Company did no t record any research and development expense in connection with the Amgen Agreement.

Income taxes

Income taxes	9 Months Ended
	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income taxes	10. Income taxes During the three and nine months ended September 30, 2024 and 2023, the Company did no t record any income tax benefits for the net operating losses incurred or for the research and development tax credits generated in each period due to its uncertainty of realizing a benefit from those items. All of the Company’s operating losses since inception have been generated in the United States. On August 16, 2022, the Inflation Reduction Act of 2022 (“IRA”) was signed into law. The IRA includes implementation of a new alternative minimum tax, an excise tax on stock buybacks, and significant tax incentives for energy and climate initiatives, among other provisions. The Company is evaluating the provisions included under the IRA and does not expect the provisions to have a material impact to the Company’s condensed consolidated financial statements. Beginning in 2022, the Tax Cuts and Jobs Act of 2017 eliminates the option to deduct research and development expenditures in the period incurred and requires amortization over five years or fifteen years pursuant to the Internal Revenue Code of 1986, as amended (the“IRC”) Section 174. Although Congress is considering legislation that would defer the amortization requirement to later years, there is no assurance that the requirement to amortize will be repealed or otherwise modified. In general, for taxable years beginning on or after January 1, 2015, California law conforms to the IRC as of January 1, 2015. California has not conformed to the federal changes made to the IRC by the Tax Cuts and Jobs Act (Public Law 115-97, enacted on December 22, 2017). In the context of IRC 174, California allows taxpayers to immediately expense R&D costs or capitalize and amortize R&D expenditures over a 5-year recovery period. Thus, the new requirements to capitalize R&D will have no material impact on the state income tax provision.

Net loss per share

Net loss per share	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Net loss per share	11. Net loss per share Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Numerator: Net loss $ ( 72,705 ) $ ( 39,659 ) $ ( 182,036 ) $ ( 96,573 ) Denominator: Weighted average common shares outstanding, basic and diluted 69,442,136 55,613,120 65,982,798 51,506,766 Net loss per share, basic and diluted $ ( 1.05 ) $ ( 0.71 ) $ ( 2.76 ) $ ( 1.87 ) The Company’s potentially dilutive securities, which include stock options, warrants and unvested restricted stock units, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: Three and Nine Months Ended September 30, 2024 2023 Options to purchase common stock 7,296,394 5,750,601 Unvested restricted stock units 536,717 142,498 Warrants to purchase common stock 64,257 45,898 Warrants available for future grant 211,137 137,700 8,108,505 6,076,697

Commitments and contingencies

Commitments and contingencies	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	12. Commitments and contingencies Operating lease In February 2020, the Company entered into a seven-year agreement to occupy 6,647 square feet of office space in South San Francisco, California. The lease commenced on July 10, 2020 when the Company took occupancy of the leased space and the lease was determined to be operating classified. Under the agreement, the Company is required to make approximately $ 2,300 in total minimum payments during the term. The Company is also required to pay its proportionate share of building operating and tax costs after the first year under lease which are not included in the measurement of the lease and treated as variable lease cost and expensed when incurred. As of September 30, 2024, maturities of the Company’s operating lease liability was as follows: 2024 $ 84 2025 341 2026 351 2027 208 Total future minimum lease payments 984 Less imputed interest ( 96 ) Present value of operating lease liabilities $ 888 As of September 30, 2024, the total lease liability was $ 888 , of which $ 605 was noncurrent and $ 283 was short-term and classified within “ Accrued expenses and other current liabilities ” on the condensed consolidated balance sheet. For the three and nine months ended September 30, 2024 and 2023, the components of operating lease cost were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Lease cost: Statement of Operations Classification: Operating lease cost General and administrative expense $ 81 $ 81 $ 243 $ 243 Short-term lease cost General and administrative expense 36 36 126 125 Variable operating lease cost General and administrative expense 14 8 40 27 Total operating lease cost $ 131 $ 125 $ 409 $ 395 Other information: Cash paid for amounts included in the measurement of operating lease liability $ 84 81 $ 247 $ 240 Weighted average remaining lease term (years) 2.8 3.8 2.8 3.8 Weighted average discount rate 7.6 % 7.6 % 7.6 % 7.6 % Research and manufacturing and other commitments The Company has entered into agreements with contract research organizations and contract manufacturing organizations to provide services in connection with its nonclinical studies and clinical trials and to manufacture clinical development materials. As of September 30, 2024, the Company had non-cancelable purchase and other commitments under these agreements totaling $ 26,647 . Indemnification agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not currently aware of any indemnification claims and has not accrued any liabilities related to such obligations in its condensed consolidated financial statements as of September 30, 2024. Legal proceedings The Company does not have contingency reserves established for any litigation liabilities. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses costs related to such legal proceedings as they are incurred. On April 26, 2024, a purported stockholder of the Company filed a lawsuit, captioned Klobus v. Akero Therapeutics, Inc., No. 3:24-cv-02534 (N.D. Cal.), in the U.S. District Court for the Northern District of California against the Company and three of its officers. The suit purports to be filed on behalf of a class of stockholders who purchased or otherwise acquired Company common stock between September 13, 2022 and October 9, 2023. The suit asserts claims under the Exchange Act for alleged misstatements and omissions regarding the Company’s Phase 2b SYMMETRY study. The complaint seeks damages in an unspecified amount. The court appointed lead plaintiffs and lead counsel on August 2, 2024. Lead Plaintiffs filed an amended complaint on September 24, 2024. Defendants’ anticipated motion to dismiss is due on November 18, 2024. A hearing on Defendants’ anticipated motion to dismiss has not yet been scheduled. Due to the early stage of this matter, it is not possible to determine the probability or amount of potential related costs. The Company intends to vigorously defend against the lawsuit.

Subsequent event

Subsequent event	9 Months Ended
	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent event	13. Subsequent event The Company evaluated subsequent events through the date on which these condensed consolidated financial statements were issued. Based on this evaluation, it was determined that no subsequent events occurred that require recognition or disclosure in its financial statements for the three and nine months ended September 30, 2024.

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Unaudited interim financial statements	Unaudited interim financial statements The accompanying unaudited condensed consolidated financial statements have been prepared by the Company in accordance with GAAP for interim financial reporting and as required by Regulation S-X, Rule 10-01. The unaudited condensed consolidated financial statements have been prepared on the same basis as the Company’s audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the Company’s condensed consolidated balance sheet as of September 30, 2024, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2024 and 2023, the condensed consolidated statement of stockholders’ equity (deficit) for the three months ended March 31, 2024 and 2023, three months ended June 30, 2024 and 2023 and the three months ended September 30, 2024 and 2023 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2024 and 2023. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2024 and 2023 are unaudited. The results for the three and nine months ended September 30, 2024 are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period.
Operating segment information	Operating segment information Operating segments are defined as components of an enterprise for which separate and discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company has one operating segment. The Company’s focus is the research and development of treatments for patients with serious metabolic diseases marked by high unmet medical need, including MASH. The Company’s chief operating decision maker, its chief executive officer, manages the Company’s operations on a consolidated basis for the purpose of allocating resources.
Use of estimates	Use of estimates The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the condensed consolidated financial statements and accompanying notes. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the recognition of research and development expenses, stock-based compensation expense, warrant liabilities and the valuation allowance for deferred tax assets. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.
Cash and cash equivalents	Cash and cash equivalents The Company considers all highly liquid investments with original maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts. The fair value of cash equivalents approximate their carrying values due to the short-term nature of such financial instruments.
Short and long-term marketable securities	Short and long-term marketable securities The Company invests in short-term and long-term marketable securities, primarily money market funds, commercial paper, U.S. treasury securities and corporate debt securities. The Company continually evaluates the credit ratings of its investment portfolio and underlying securities. The Company invests in accordance with its investment policy and invests at the date of purchase in securities with high ratings from top rating agencies. The Company classifies its short- and long-term marketable securities as available-for-sale securities and reports them at fair value in short-term and long-term marketable securities on the condensed consolidated balance sheets with related unrealized gains and losses included within accumulated other comprehensive gain (loss) on the condensed consolidated balance sheets. The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in other income on the condensed consolidated statements of operations and comprehensive loss. When the fair value is below the amortized cost of a marketable security, the Company reviews and determines whether the impairment is due to credit-related factors or noncredit-related factors. The credit-related impairment amount is recognized in other income on the condensed consolidated statements of operations and comprehensive loss, with a corresponding allowance for credit losses account in the condensed consolidated balance sheet. Subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in the condensed consolidated statements of operations. There were no credit losses recorded during the periods ended September 30, 2024 and 2023.
Concentrations of credit risk	Concentrations of credit risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents and short- and long-term marketable securities. Periodically, the Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company deposits its cash investments in financial institutions that it believes have high credit quality and has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. At September 30, 2024, all of the Company's cash, cash equivalents and short and long-term investments were held at three accredited financial institutions.
Leases	Leases The Company determines whether an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether the Company has the right to control the identified asset. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Lease liabilities are recognized at the lease commencement date based on the present value of future lease payments over the lease term. ROU assets are based on the measurement of the lease liability and are further adjusted by any lease payments made prior to or on lease commencement, lease incentives received and initial direct costs incurred, as applicable. The Company has elected to not recognize leases with a lease term of one year or less on its balance sheet. Operating lease costs included in the measurement of the lease are recognized on a straight-line basis over the lease term. Variable lease costs are expensed as incurred as an operating expense. The Company determines the lease classification and the present value of future lease payments at the time of the lease commencement using an incremental borrowing rate that it estimates based upon the Company’s credit risk and term of the lease. The interest rate implicit in lease contracts has not historically been readily determinable and the Company must therefore use the appropriate incremental borrowing rate to measure its leases. To estimate the incremental borrowing rate, a credit rating applicable to the Company is estimated using a synthetic credit rating analysis since the Company does not currently have a rating agency-based credit rating.
Research and development costs	Research and development costs Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred to discover, research and develop drug candidates, including personnel expenses, stock-based compensation expense, third-party license fees and external costs including fees paid to consultants, contract manufacturing organizations, or CMOs, and clinical research organizations, or CROs, in connection with drug product manufacturing, nonclinical studies and clinical trials, and other related clinical trial fees, such as for investigator grants, patient screening, laboratory work, clinical trial database management, clinical trial material management and statistical compilation and analysis. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered or the services rendered. Foreign currency transaction gains and losses related to the purchase of contract manufacturing services are included as a component of research and development expense. Costs incurred in obtaining technology licenses are charged immediately to research and development expense if the technology licensed has not reached technological feasibility and has no alternative future uses.
Accrued and prepaid research and development expenses	Accrued and prepaid research and development expenses The Company has entered into various research and development and other agreements with commercial firms, researchers and others for provisions of goods and services. These agreements are generally cancelable, and the related costs are recorded as research and development expenses as incurred. The Company makes estimates of accrued and prepaid research and development expenses as of each balance sheet date based on facts and circumstances known at that time. When evaluating the adequacy of the accrued liabilities and the appropriateness of the prepaid expenses, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued and prepaid balances at the end of any reporting period. Actual results could differ materially from the Company's estimates .
Stock-based compensation	Stock-based compensation The Company makes stock-based awards from its stock compensation plans (see Note 8). The Company measures all stock option awards granted to employees and nonemployees based on the fair value on the date of the grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis. The Company accounts for forfeitures as they occur. The Company recognizes stock-based compensation expense for awards that contain performance-based conditions using the accelerated attribution method when management determines it is probable that the performance condition will be satisfied. The Company measures restricted stock unit awards based on the market closing price of the Company's common stock on the grant date. Stock-based compensation expense for these awards is recognized on a straight-line basis over the requisite service period, generally four years. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model, which requires inputs based on certain subjective assumptions, including the expected stock price volatility, the expected term of the option, the risk-free interest rate for a period that approximates the expected term of the option, and the Company's expected dividend yield. The Company currently estimates its share price volatility using a combined weighting of the historical volatility of publicly traded peer companies and the volatility of its traded share price and expects to continue to do so until mid-2025. The expected term of the Company's stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends on common stock and the expectation that it will not pay any cash dividends in the foreseeable future. Compensation expense for purchases under the Employee Stock Purchase Plan is recognized based on the fair value of the common stock estimated based on the closing price of our common stock as reported on the date of offering, less the purchase discount percentage provided for in the plan. The Company classifies stock-based compensation expense in its condensed consolidated statement of operations and comprehensive loss in the same manner in which the award recipient's payroll costs are classified or in which the award recipient's service payments are classified.
Loan payable	Loan payable Loan Payable represents borrowings under the Loan and Security Agreement, dated June 15, 2022 (“Loan Agreement”) with Hercules Capital, Inc. (“Hercules”), subsequently amended on June 7, 2023 and February 28, 2024, which the Company has accounted for as a debt financing arrangement. Interest expense is accrued using the effective interest rate method over the estimated period the loan will be repaid. Loan issuance costs have been recorded as a debt discount in the condensed consolidated balance sheets and are being amortized and recorded as interest expense throughout the life of the Loan Agreement using the effective interest rate method. The Company considered whether there were any embedded features in the Loan Agreement that require bifurcation and separate accounting as derivative financial instruments pursuant to Accounting Standards Codification (“ASC”) Topic 815, Derivatives and Hedging . The Loan Agreement was amended on February 28, 2024. The Company accounted for the amendment as a debt modification arrangement pursuant to ASC Topic 470, Debt—Modifications and Extinguishments.
Warrant liabilities	Warrant liabilities The Company accounts for warrants anticipated to be issued in the future under the Loan Agreement as liabilities and measures them at fair value using the Black-Scholes valuation model. The warrants are subject to remeasurement at each prospective balance sheet date, with any changes in the fair value recorded in the condensed consolidated statements of operations.
Comprehensive loss	Comprehensive loss Comprehensive loss includes net loss as well as other changes in stockholders' equity (deficit) that result from transactions and economic events other than those with stockholders. The Company’s comprehensive loss is comprised of net loss and changes in unrealized gains and losses on its short- and long-term marketable securities .
Recently issued accounting standards not yet adopted	Recently issued accounting standards not yet adopted In November 2023, the FASB, issued ASU No. 2023-07 , Segment Reporting (Topic 280), Improvements to Reportable Segment Disclosures, to improve reportable segment disclosure requirements. The amendment introduced new requirements to disclose significant segment expenses regularly provided to the chief operating decision maker (“CODM”) and extend certain annual disclosures to interim periods. Entities with a single reportable segment must apply ASC 280 in its entirety, are permitted to report more than one measure of segment profit or loss under certain conditions and are required to disclose the title and position of the CODM. ASU No. 2023-07 is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the effect this standard will have on its condensed consolidated financial statements and related disclosures. In December 2023, the Financial Accounting Standards Board (“FASB”), issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740), Improvements to Income Tax Disclosures, to enhance the transparency and decision usefulness of income tax disclosures. The enhancement will provide information to better assess how an entity’s operations and related tax risks and tax planning and operational opportunities affect its tax rate and prospects for future cash flows. Investors currently rely on the rate reconciliation table and other disclosures, including total income taxes paid, to evaluate income tax risks and opportunities. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and early adoption is permitted. The Company is currently evaluating the impact ASU No. 2023-09 will have on its condensed consolidated financial statements and related disclosures.

Fair value of financial assets

Fair value of financial assets and liabilities (Tables)	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Summary of assets and liabilities measured at fair value on a recurring basis	The following is a summary of the Company's financial assets and liabilities measured at fair value on a recurring basis as of September 30, 2024 and December 31, 2023: September 30, 2024 Total Level 1 Level 2 Level 3 Money market funds $ 303,324 $ 303,324 $ — $ — U.S. Treasury securities 248,440 248,440 — — U.S. Government agency securities 70,258 — 70,258 — Commercial paper 59,078 — 59,078 — Corporate debt securities 93,230 — 93,230 — Total assets $ 774,330 $ 551,764 $ 222,566 $ — Warrant liabilities $ 203 $ — $ — $ 203 Total liabilities $ 203 $ — $ — $ 203 December 31, 2023 Total Level 1 Level 2 Level 3 Money market funds $ 206,879 $ 206,879 $ — $ — U.S. Treasury securities 117,307 117,307 — — U.S. Government agency securities 133,297 — 133,297 — Commercial paper 68,708 — 68,708 — Corporate debt securities 15,774 — 15,774 — Total assets $ 541,965 $ 324,186 $ 217,779 $ — Warrant liabilities $ 54 $ — $ — $ 54 Total liabilities $ 54 $ — $ — $ 54

Short and long-term marketabl_2

Short and long-term marketable securities (Tables)	9 Months Ended
	Sep. 30, 2024
Short and long-term marketable securities
Summary of short-term and long-term marketable securities	The following is a summary of short-term and long-term marketable securities as of September 30, 2024 and December 31, 2023 : September 30, 2024 Amortized cost Gross unrealized gains Gross unrealized losses Credit losses Fair value Money market funds $ 303,324 $ — $ — $ — $ 303,324 U.S. Treasury securities 246,981 1,459 — — 248,440 U.S. Government agency securities 70,042 216 — — 70,258 Commercial paper 58,954 124 — — 59,078 Corporate debt securities 92,926 304 — — 93,230 $ 772,227 $ 2,103 $ — $ — $ 774,330 Cash equivalents $ 303,324 Short-term marketable securities 401,182 Long-term marketable securities 69,824 $ 774,330 December 31, 2023 Amortized cost Gross unrealized gains Gross unrealized losses Credit losses Fair value Money market funds $ 206,879 $ — $ — $ — $ 206,879 U.S. Treasury securities 117,058 255 ( 6 ) — 117,307 U.S. Government agency securities 133,279 78 ( 60 ) — 133,297 Commercial paper 68,707 10 ( 9 ) — 68,708 Corporate debt securities 15,773 1 — — 15,774 $ 541,696 $ 344 $ ( 75 ) $ — $ 541,965 Cash equivalents $ 206,879 Short-term marketable securities 315,803 Long-term marketable securities 19,283 $ 541,965
Schedule of contractual maturities of short-term and long term marketable securities	The following table presents the contractual maturities of the Company's short-term and long-term marketable securities as of September 30, 2024 and December 31, 2023. September 30, 2024 December 31, 2023 Due within one year $ 401,182 $ 315,803 Due after one year through two years 69,824 19,283 Total $ 471,006 $ 335,086

Accrued expenses and other cu_2

Accrued expenses and other current liabilities (Tables)	9 Months Ended
	Sep. 30, 2024
Accrued expenses and other current liabilities
Schedule of accrued expenses and other current liabilities	The following is a summary of accrued expenses and other current liabilities as of September 30, 2024 and December 31, 2023 : September 30, 2024 December 31, 2023 Accrued external research and development expenses $ 12,789 $ 10,041 Accrued employee compensation and benefits 4,369 1,296 Accrued legal and professional fees 279 231 Short-term lease liability and other 631 522 $ 18,068 $ 12,090

Loan Payable and Warrant Liab_2

Loan Payable and Warrant Liability (Tables)	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Schedule of Future principal Debt Payments on Loan Payable	Future principal debt payments on the currently outstanding loan payable as of September 30, 2024 and December 31, 2023 are as follows (in thousands): September 30, 2024 December 31, 2023 2024 $ — $ — 2025 — 7,343 2026 27,655 16,118 2027 7,345 1,539 Total principal outstanding 35,000 25,000 End of term charge 2,048 1,463 Total principal outstanding and end of term charge 37,048 26,463 Unamortized discount and issuance costs ( 1,925 ) ( 1,499 ) Loan Payable $ 35,123 $ 24,964 Loan Payable - current $ — $ — Loan Payable - noncurrent 35,123 24,964 Loan Payable $ 35,123 $ 24,964
Schedule of Assumptions Used to Determine Estimated Fair Value of Warrant Liability	The Company estimated the fair value of the warrant liability as of September 30, 2024 using probability assumptions of achieving the future milestones and using the Black-Scholes model based on the following key assumptions: Nine Months Ended September 30, 2024 2023 Expected term (in years) 4.7 5.7 Expected volatility 88.41 % 79.55 % Risk-free interest rate 3.58 % 4.60 % Expected dividend yield 0.00 % 0.00 %

Stockholder's equity (deficit)

Stockholder's equity (deficit) (Tables)	9 Months Ended
	Sep. 30, 2024
Stockholders' Equity Note [Abstract]
Schedule of common stock reserved for issuance	The following shares of common stock were reserved for issuance as follows: September 30, 2024 December 31, 2023 Options outstanding under the 2018 Stock Option and Grant Plan 679,016 1,114,189 Options outstanding under the 2019 Stock Option and Incentive Plan 6,617,378 5,785,788 Unvested restricted stock units outstanding under the 2019 Stock Option and Incentive Plan 536,717 371,952 Warrants to purchase common stock associated with Loan Agreement 64,257 45,898 Options available for future grant 2,892,453 1,917,356 Warrants available for future grant 211,137 137,700 Common stock available for ATM program 11,722,981 2,708,234 2019 Employee Stock Purchase Plan 1,980,783 1,586,224 24,704,722 13,667,341

Stock-based awards (Tables)

Stock-based awards (Tables)	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Schedule of assumptions used to determine grant-date fair value of stock options granted	The assumptions that the Company used to determine the grant-date fair value of stock options granted to employees, directors and consultants as follows, presented on a weighted average basis: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Expected term (in years) 5.96 5.85 5.93 5.88 Expected volatility 88.06 % 79.75 % 86.38 % 78.37 % Weighted average risk-free interest rate 4.41 % 4.18 % 4.30 % 3.91 % Expected dividend yield 0.00 % 0.00 % 0.00 % 0.00 %
Summary of stock option activity	The following table summarizes the Company’s stock option activity since December 31, 2023: Weighted- Weighted- Average Average Aggregate Exercise Remaining Intrinsic Number Price per Contractual Value of Options Share Term (years) (000's) Balance outstanding, December 31, 2023 6,899,977 $ 22.35 7.67 $ 35,133 Options granted 1,018,350 $ 22.31 Options exercised ( 601,270 ) $ 8.15 Options cancelled ( 20,663 ) $ 39.16 Balance outstanding, September 30, 2024 7,296,394 $ 23.47 7.37 $ 56,484 Vested and expected to vest, September 30, 2024 7,296,394 $ 23.47 7.37 $ 56,484 Exercisable, September 30, 2024 4,447,229 $ 22.23 6.50 $ 38,146
Summary of restricted stock activity	The following table summarizes the Company’s RSUs activity since December 31, 2023: Weighted- Weighted- Average Average Aggregate Grant Date Remaining Intrinsic Underlying Fair Value per Contractual Value Shares Share Term (years) (000's) Balance outstanding, December 31, 2023 371,952 $ 28.53 1.98 $ 8,685 Granted 261,288 $ 23.46 Vested ( 92,628 ) $ 29.47 Cancelled or forfeited ( 3,895 ) $ 23.48 Balance outstanding, September 30, 2024 536,717 $ 25.94 1.63 $ 15,398
Summary of stock-based compensation expense	The following table summarizes the Company’s stock-based compensation expense during the three and nine months ended September 30, 2024 and 2023: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Classified within research and development expense $ 2,903 $ 1,986 $ 8,487 $ 5,485 Classified within general and administrative expense 4,565 3,753 14,035 9,896 Total stock-based compensation expense $ 7,468 $ 5,739 $ 22,522 $ 15,381

Net loss per share (Tables)

Net loss per share (Tables)	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Schedule of basic and diluted net loss per share attributable to common stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Numerator: Net loss $ ( 72,705 ) $ ( 39,659 ) $ ( 182,036 ) $ ( 96,573 ) Denominator: Weighted average common shares outstanding, basic and diluted 69,442,136 55,613,120 65,982,798 51,506,766 Net loss per share, basic and diluted $ ( 1.05 ) $ ( 0.71 ) $ ( 2.76 ) $ ( 1.87 )
Schedule of computation of diluted net loss per share attributable to common stockholders	Three and Nine Months Ended September 30, 2024 2023 Options to purchase common stock 7,296,394 5,750,601 Unvested restricted stock units 536,717 142,498 Warrants to purchase common stock 64,257 45,898 Warrants available for future grant 211,137 137,700 8,108,505 6,076,697

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Schedule of maturity of the Company's operating lease liabilities	As of September 30, 2024, maturities of the Company’s operating lease liability was as follows: 2024 $ 84 2025 341 2026 351 2027 208 Total future minimum lease payments 984 Less imputed interest ( 96 ) Present value of operating lease liabilities $ 888
Schedule of components of operating lease expense	For the three and nine months ended September 30, 2024 and 2023, the components of operating lease cost were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Lease cost: Statement of Operations Classification: Operating lease cost General and administrative expense $ 81 $ 81 $ 243 $ 243 Short-term lease cost General and administrative expense 36 36 126 125 Variable operating lease cost General and administrative expense 14 8 40 27 Total operating lease cost $ 131 $ 125 $ 409 $ 395 Other information: Cash paid for amounts included in the measurement of operating lease liability $ 84 81 $ 247 $ 240 Weighted average remaining lease term (years) 2.8 3.8 2.8 3.8 Weighted average discount rate 7.6 % 7.6 % 7.6 % 7.6 %

Nature of the business and ba_2

Nature of the business and basis of presentation (Details) $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($) Patient Clinicaltrial	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Organization, consolidation and presentation of financial statements [Line Items]
Number of patients treated | Patient							300
Additional Paid in Capital	$ 1,427,900						$ 1,427,900
Proceeds from its initial public offering							105,800
Proceeds from the sale of redeemable convertible preferred stock							90,500
Proceeds from the sales of common stock in equity offerings							1,196,600
Venture debt borrowings	35,000						35,000
Proceeds from equity investment from Pfizer, Inc.							25,000
Net loss	72,705	$ 55,987	$ 53,344	$ 39,659	$ 31,083	$ 25,831	182,036	$ 96,573	$ 151,759	$ 112,033
Accumulated deficit	(756,132)						(756,132)		$ (574,096)
Cash, cash equivalents and short-term marketable securities	$ 787,071						$ 787,071
SYMMETRY Study | Nash Patients with Pre-Cirrhotic and Compensated Cirrhosis
Organization, consolidation and presentation of financial statements [Line Items]
Number of ongoing clinical trials | Clinicaltrial							3

Fair value of financial asset_2

Fair value of financial assets and liabilities - Textual (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers into level 3 Assets	$ 0	$ 0
Transfers out of level 3 Assets	0	0
Transfers into level 3 liabilities	0	0
Transfers out of level 3 liabilities	$ 0	$ 0

Fair value of financial asset_3

Fair value of financial assets and liabilities - Recurring (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 774,330	$ 541,965
Liabilities	203	54
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	303,324	206,879
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	248,440	117,307
U.S. Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	70,258	133,297
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	59,078	68,708
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	93,230	15,774
Warrant liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	203	54
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	551,764	324,186
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	303,324	206,879
Level 1 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	248,440	117,307
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	222,566	217,779
Level 2 | U.S. Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	70,258	133,297
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	59,078	68,708
Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	93,230	15,774
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	203	54
Level 3 | Warrant liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 203	$ 54

Short-term and long-term market

Short-term and long-term marketable securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	$ 772,227	$ 541,696
Gross unrealized gains	2,103	344
Gross unrealized losses		(75)
Fair value	774,330	541,965
Cash equivalents	303,324	206,879
Short-term marketable securities	401,182	315,803
Long-term marketable securities	69,824	19,283
Total	774,330	541,965
Money market funds
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	303,324	206,879
Fair value	303,324	206,879
U.S. Treasury securities
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	246,981	117,058
Gross unrealized gains	1,459	255
Gross unrealized losses		(6)
Fair value	248,440	117,307
Corporate debt securities
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	92,926	15,773
Gross unrealized gains	304	1
Fair value	93,230	15,774
U.S. Government agency securities
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	70,042	133,279
Gross unrealized gains	216	78
Gross unrealized losses		(60)
Fair value	70,258	133,297
Commercial paper
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	58,954	68,707
Gross unrealized gains	124	10
Gross unrealized losses		(9)
Fair value	$ 59,078	$ 68,708

Short and long-term marketabl_3

Short and long-term marketable securities - Schedule of contractual maturities of short-term and long term marketable securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities [Abstract]
Due within one year	$ 401,182	$ 315,803
Due after one year through five years	69,824	19,283
Total	$ 471,006	$ 335,086

Accrued expenses and other cu_3

Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accrued expenses and other current liabilities
Accrued external research and development expenses	$ 12,789	$ 10,041
Accrued employee compensation and benefits	4,369	1,296
Accrued legal and professional fees	279	231
Short-term lease liability and other	631	522
Total accrued expenses and other current liabilities	$ 18,068	$ 12,090

Loan Payable and Warrant Liab_3

Loan Payable and Warrant Liability - Textual (Details)				1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2024 USD ($) shares	Mar. 10, 2023 USD ($) shares	Jun. 15, 2022 USD ($) Tranche	Mar. 31, 2023 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($)	Nov. 30, 2024 $ / shares	Dec. 31, 2023 $ / shares
Debt Instrument [Line Items]
Proceeds from term loan							$ 10,000,000	$ 15,000,000
Amortization of debt issuance costs and discount							$ 433,000	328,000
Common stock, par value (in dollars per share) | $ / shares							$ 0.0001		$ 0.0001	$ 0.0001
Additional warrants to purchase shares	$ 431,000	$ 330,000			$ 431,000	$ 330,000
Fair value change in warrant liability							$ 526,000	$ 118,000
Hercules
Debt Instrument [Line Items]
Issued warrants to purchase shares of common stock | shares	18,359	9,180
Loan Agreement
Debt Instrument [Line Items]
Percentage of prepayment charge of outstanding principal balance			1%
End of term charge of outstanding principal balance, in percentage			5.85%
Amortization of debt issuance costs and discount			$ 2,048,000
Issued warrants to purchase shares of common stock | shares							36,718
Recognized initial warrants at relative fair value							$ 227,000
Loan Agreement | Hercules
Debt Instrument [Line Items]
Proceeds from term loan	$ 10,000,000	$ 15,000,000
Loan Agreement | Term Loan | Hercules
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 150,000,000
Number of tranches available for loan | Tranche			5
Proceeds from term loan			$ 10,000,000
Term loan, description							Under the terms of the Loan Agreement, the Company received $10,000 upon closing, $15,000 was borrowed in March 2023 and an additional $10,000 was borrowed in connection with the second amendment on February 28, 2024 (the “Tranche I and Tranche II Commitments”). At the sole discretion of the Company, $30,000 is available to be drawn from June 15, 2024 through June 15, 2025 (“Tranche III Commitment”). Also at the sole discretion of the Company, an additional $35,000 is available to be drawn at the earlier of the full draw of Tranche III or June 15, 2025 through June 15, 2026 (“Tranche IV Commitment”). An additional $50,000 may become available to the Company prior to January 1, 2026, subject to Hercules' approval (“Tranche V Commitment”).
Maturity date			Mar. 01, 2027
Variable annual rate			7.65%
Issued warrants to purchase shares of common stock | shares							211,137
Loan Agreement | Term Loan | Hercules | Prime Rate
Debt Instrument [Line Items]
Variable annual rate			3.65%
Loan Agreement | Term Loan First Tranche | Hercules
Debt Instrument [Line Items]
Proceeds from term loan	$ 10,000,000	$ 15,000,000		$ 15,000,000
Loan Agreement | Term Loan Second Tranche | Hercules
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 10,000,000
Loan Agreement | Term Loan Third Tranche | Hercules | June 15, 2024 through June 15, 2025
Debt Instrument [Line Items]
Amount available to drawn			$ 30,000,000
Borrowing available start date			Jun. 15, 2024
Borrowing available end date			Jun. 15, 2025
Loan Agreement | Term Loan Fourth Tranche | Hercules | June 15, 2025 through June 15, 2026
Debt Instrument [Line Items]
Additional borrowing capacity			$ 35,000,000
Borrowing available start date			Jun. 15, 2025
Borrowing available end date			Jun. 15, 2026
Loan Agreement | Term Loan Fifth Tranche | Hercules | Prior To January 1, 2026
Debt Instrument [Line Items]
Additional borrowing capacity			$ 50,000,000
Warrants to Purchase Common Stock | Loan Agreement | Term Loan | Hercules
Debt Instrument [Line Items]
Common stock, par value (in dollars per share) | $ / shares							$ 0.0001
Maximum percentage of warrants purchased							1.50%

Loan Payable and Warrant Liab_4

Loan Payable and Warrant Liability - Schedule of Future principal Debt Payments on Loan Payable (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Long-Term Debt, Fiscal Year Maturity [Abstract]
2025		$ 7,343
2026	$ 27,655	16,118
2027	7,345	1,539
Total principal outstanding	35,000	25,000
End of term charge	2,048	1,463
Total principal outstanding and end of term charge	37,048	26,463
Unamortized discount and issuance costs	(1,925)	(1,499)
Loan Payable	35,123	24,964
Loan Payable - noncurrent	$ 35,123	$ 24,964

Loan Payable and Warrant Liab_5

Loan Payable and Warrant Liability - Schedule of Assumptions Used to Determine Estimated Fair Value of Warrant Liability (Details)	Sep. 30, 2024	Sep. 30, 2023
Measurement Input, Expected Term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term (in years)	4 years 8 months 12 days	5 years 8 months 12 days
Measurement Input, Price Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of the Warrants, Measurement input	0.8841	0.7955
Measurement Input, Risk-Free Interest Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of the Warrants, Measurement input	0.0358	0.046
Measurement Input, Expected Dividend Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of the Warrants, Measurement input	0	0

Stockholder's equity (deficit_2

Stockholder's equity (deficit) - Common stock (Details)										1 Months Ended		9 Months Ended
	May 10, 2024 USD ($)	Mar. 08, 2024 USD ($) $ / shares shares	May 16, 2023 USD ($) $ / shares shares	Mar. 17, 2023 USD ($)	Sep. 19, 2022 USD ($) $ / shares shares	Jun. 17, 2022 USD ($)	Jun. 15, 2022 $ / shares shares	Jul. 10, 2020 USD ($) $ / shares shares	Jun. 24, 2019 USD ($) $ / shares shares	Feb. 29, 2024 USD ($) $ / shares shares	Apr. 30, 2023 $ / shares shares	Sep. 30, 2024 USD ($) Vote $ / shares shares	Nov. 30, 2024 $ / shares	Dec. 31, 2023 $ / shares shares	May 31, 2023 $ / shares	Jun. 18, 2019 shares
Class of Stock [Line Items]
Common stock, shares authorized												150,000,000		150,000,000
Common stock, par value (in dollars per share) | $ / shares												$ 0.0001	$ 0.0001	$ 0.0001
Number of votes per share | Vote												1
Cash dividend declared | $ / shares												$ 0
Cash dividend paid | $ / shares												$ 0
Net proceeds from the sales of common stock in equity offerings | $												$ 1,196,600,000
Common stock, shares issued												69,614,587		55,754,445
Common stock, shares outstanding												69,614,587		55,754,445
Common stock were reserved for issuance
Options available for future grant												24,704,722		13,667,341
Jeffries
Class of Stock [Line Items]
Net proceeds from the sales of common stock in equity offerings | $			$ 210,956,000
Offering costs | $			$ 9,061,000
Sale of stock under agreement			5,238,500
Sale of stock, price per share | $ / shares			$ 42
Employee Stock Option
Common stock were reserved for issuance
Options available for future grant												2,892,453		1,917,356
Common stock Available under ATM Offering
Class of Stock [Line Items]
Net proceeds from the sales of common stock in equity offerings | $						$ 24,647,000				$ 10,604,000		$ 123,824,000
Offering costs | $										$ 271,000		$ 3,578,000
Sale of stock under agreement										500,000	3,006,052
Sale of stock, price per share | $ / shares										$ 21.75	$ 42.38				$ 42.38
Common stock were reserved for issuance
Options available for future grant												11,722,981		2,708,234
Common stock Available under ATM Offering | Pfizer Inc
Class of Stock [Line Items]
Sale of stock under agreement							2,525,252
Sale of stock, price per share | $ / shares							$ 9.9
Warrants to Purchase Common Stock
Common stock were reserved for issuance
Options available for future grant												64,257		45,898
Warrants Available for Future Grant
Common stock were reserved for issuance
Options available for future grant												211,137		137,700
2018 Stock option and grant plan
Common stock were reserved for issuance
Options available for future grant												679,016		1,114,189		107,635
2019 Stock Option and Incentive plan
Common stock were reserved for issuance
Options available for future grant												6,617,378		5,785,788
2019 Stock Option and Incentive plan | Unvested Restricted Stock Units
Common stock were reserved for issuance
Options available for future grant												536,717		371,952
2019 Employee Stock Purchase Plan
Common stock were reserved for issuance
Options available for future grant												1,980,783		1,586,224
Maximum | Common stock Available under ATM Offering
Class of Stock [Line Items]
Share Issued value under agreement | $				$ 200,000,000
IPO
Class of Stock [Line Items]
Public offering price | $ / shares									$ 16
Net proceeds from the sales of common stock in equity offerings | $									$ 98,394,000
Offering costs | $									$ 2,942,000
Number of shares converted									21,056,136
Common stock, shares issued									6,612,500
Follow Up Public Offering
Class of Stock [Line Items]
Share Issued under agreement					8,846,154			6,012,390
Public offering price | $ / shares		$ 29			$ 26			$ 36
Net proceeds from the sales of common stock in equity offerings | $		$ 344,838,000			$ 216,200,000			$ 203,460,000
Offering costs | $		$ 22,011,000			$ 13,800,000
Common stock, shares issued		12,650,000
Proceeds from issuance of common stock before deducting offering costs | $		$ 401,000
Over allotment | Maximum
Class of Stock [Line Items]
Share Issued under agreement		1,650,000			1,153,846			784,224
Common stock, shares issued									862,500
Amended Sales Agreement
Class of Stock [Line Items]
Share Issued value under agreement | $	$ 200,000,000
Amended Sales Agreement | Maximum
Class of Stock [Line Items]
Share Issued value under agreement | $	$ 261,723,000

Stockholder's equity (deficit_3

Stockholder's equity (deficit) - Undesignated preferred stock and Restricted common stock (Details) - Undesignated Preferred Stock	Sep. 30, 2024 $ / shares shares
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Maximum
Class of Stock [Line Items]
Preferred stock, shares authorized	10,000,000

Stockholder's equity (deficit_4

Stockholder's equity (deficit) - Warrants Associated with Loan Agreement (Details) - USD ($)				3 Months Ended		9 Months Ended
	Feb. 28, 2024	Mar. 10, 2023	Jun. 15, 2022	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Class of Stock [Line Items]
Additional warrants to purchase shares	$ 431,000	$ 330,000		$ 431,000	$ 330,000
Proceeds from term loan						$ 10,000,000	$ 15,000,000
Loan Agreement
Class of Stock [Line Items]
Issued warrants to purchase shares of common stock						36,718
Hercules Capital Inc and Hercules Private Global Venture Growth Fund I L.P.
Class of Stock [Line Items]
Maximum percentage of warrants purchased						1.50%
Issued warrants to purchase shares of common stock	18,359	9,180	36,718
Hercules Capital, Inc
Class of Stock [Line Items]
Issued warrants to purchase shares of common stock	18,359	9,180
Hercules Capital, Inc | Loan Agreement
Class of Stock [Line Items]
Proceeds from term loan	$ 10,000,000	$ 15,000,000
Hercules Capital, Inc | Term Loan | Loan Agreement
Class of Stock [Line Items]
Issued warrants to purchase shares of common stock						211,137
Proceeds from term loan			$ 10,000,000

Stock-based awards - Textual (D

Stock-based awards - Textual (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 18, 2019	Jun. 30, 2019	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jan. 31, 2024	Dec. 31, 2023	Jan. 31, 2023
Share-based awards
Number of shares remained available for grant			24,704,722		24,704,722			13,667,341
Weighted average grant-date fair value per share of stock options granted			$ 17.56	$ 46.01	$ 16.54	$ 47.45
Stock options granted ( in shares)					1,018,350
Exercise price					$ 22.31
Stock compensation expense			$ 7,468	$ 5,739	$ 22,522	$ 15,381
Total unrecognized compensation cost related to unvested stock-based awards			48,430		$ 48,430
Weighted average period of recognition for unrecognized compensation cost					2 years 6 months 10 days
Total unrecognized compensation cost related to RSU			$ 12,979		$ 12,979
Restricted Stock Units
Share-based awards
Weighted average grant date fair value per share granted			$ 23.16	$ 44.52	$ 23.46	$ 48.17
Weighted average period of recognition for unrecognized compensation cost					3 years 21 days
RSU granted (shares)					261,288
2018 Stock option and grant plan
Share-based awards
Number of shares of common stock issued	3,071,960
Number of shares remained available for grant	107,635		679,016		679,016			1,114,189
2019 Stock option and incentive plan
Share-based awards
Number of shares remained available for grant	107,635
Number of shares initially reserved for issuance		2,572,457
Number of additional shares reserved for issuance							2,230,177		1,874,608
Percent of shares reserved and available for issuance automatically increase annually on January 1		4%
Percentage of exercise price per share of stock options		100%
Percentage of minimum exercise price, holding more than 10% of voting power		110%
Stock options vesting period		4 years
2019 Employee stock purchase plan
Share-based awards
Number of shares initially reserved for issuance	273,869
Number of additional shares reserved for issuance							410,803		410,803
Percent of shares reserved and available for issuance automatically increase annually on January 1		1%
Number of shares reserved and available for issuance automatically increase annually on January 1 (in shares)		410,803
Maximum | 2019 Stock option and incentive plan
Share-based awards
Term of stock option		10 years

Stock-based awards - Stock opti

Stock-based awards - Stock option valuation (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Assumptions to determine grant-date fair value of stock options granted
Expected term (in years)	5 years 11 months 15 days	5 years 10 months 6 days	5 years 11 months 4 days	5 years 10 months 17 days
Expected volatility	88.06%	79.75%	86.38%	78.37%
Weighted average risk-free interest rate	4.41%	4.18%	4.30%	3.91%
Expected dividend yield	0%	0%	0%	0%

Stock based awards - Stock opti

Stock based awards - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2024	Dec. 31, 2023
Number of Options
Balance Outstanding, Beginning of the period (in shares)		6,899,977
Options granted ( in shares)		1,018,350
Options exercised ( in shares)	(123,094)	(601,270)
Options cancelled (in shares)		(20,663)
Balance Outstanding, End of the period (in shares)		7,296,394	6,899,977
Vested and expected to vest ( in shares)		7,296,394
Exercisable ( in shares)		4,447,229
Weighted-Average Exercise Price per Share
Weighted-average exercise price, Beginning of the period (in dollars per share)		$ 22.35
Weighted-average exercise price, Granted (in dollars per share)		22.31
Weighted-average exercise price, Exercised (in dollars per share)		8.15
Weighted-Average Exercise price, cancelled (in dollars per share)		39.16
Weighted-average exercise price, End of the period (in dollars per share)		23.47	$ 22.35
Weighted-average exercise price, Vested and expected to vest at end of the period (in dollars per share)		23.47
Weighted-average exercise price, Exercisable ( in dollars per share )		$ 22.23
Weighted-Average remaining contractual term (years) and Aggregate Intrinsic Value
Weighted-average remaining contractual term outstanding (in years)		7 years 4 months 13 days	7 years 8 months 1 day
Weighted-average remaining contractual term vested and expected to vest (in years)		7 years 4 months 13 days
Weighted-average remaining contractual term , Options Exercisable(in years)		6 years 6 months
Aggregate Intrinsic Value Balance outstanding		$ 56,484	$ 35,133
Aggregate Intrinsic Value Vested and Expected to vest		56,484
Aggregate Intrinsic Value Exercisable		$ 38,146

Stock-based awards - Summary of

Stock-based awards - Summary of Restricted Stock activity (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance Outstanding, Beginning of the period (in shares)			371,952
Underlying shares, Granted			261,288
Underlying shares, vested			(92,628)
Underlying shares Cancelled or forfeited			(3,895)
Balance Outstanding, End of the period (in shares)	536,717		536,717		371,952
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value per share beginning balance			$ 28.53
Weighted average grant date fair value per share granted	$ 23.16	$ 44.52	23.46	$ 48.17
Weighted average grant date fair value per share vested			29.47
Weighted average grant date fair value per share cancelled or forfeited			23.48
Weighted average grant date fair value per share ending balance	$ 25.94		$ 25.94		$ 28.53
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Weighted-Average remaining contractual term (years)			1 year 7 months 17 days		1 year 11 months 23 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value [Abstract]
Aggregate Intrinsic Value (000's)	$ 15,398		$ 15,398		$ 8,685

Stock based awards - Stock-base

Stock based awards - Stock-based compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Stock-based compensation
Total stock-based compensation expense	$ 7,468	$ 5,739	$ 22,522	$ 15,381
Research and development expense
Stock-based compensation
Total stock-based compensation expense	2,903	1,986	8,487	5,485
General and administrative expense
Stock-based compensation
Total stock-based compensation expense	$ 4,565	$ 3,753	$ 14,035	$ 9,896

Amgen license agreement (Detail

Amgen license agreement (Details) - USD ($)	1 Months Ended		3 Months Ended			9 Months Ended
	Nov. 30, 2018	Jun. 30, 2018	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2019	Sep. 30, 2024	Sep. 30, 2023
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense			$ 72,232,000	$ 38,634,000		$ 178,204,000	$ 88,406,000
Amgen Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Initial fair value of the anti-dilution right liability	$ 7,404,000
Payment for clinical trail					$ 2,500,000
Obligation for payment in connection with dosing of the first patient					7,500,000
Amgen Agreement | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate milestone payments upon the achievement of specified commercial milestones					75,000,000
Payment in connection with dosing of the first patient					$ 30,000,000
Amgen Agreement | Research and development expense
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense			$ 0	$ 0		$ 0	$ 0
Amgen Agreement | Amgen
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront payment		$ 5,000,000
Amgen Agreement | Series A Preferred Stock
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Share Issued under agreement	3,205,128
Amgen Agreement | Series A Preferred Stock | Amgen
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Share Issued under agreement		2,653,333
Share Issued value under agreement		$ 1,353,000
Ownership Interest [Member] | Amgen Agreement | Amgen
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership interest of the outstanding shares (as a percent)		10%

Income taxes - Textual (Details

Income taxes - Textual (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating Loss Carryforwards [Line Items]
Income tax benefit related to operating losses and research and development tax credits	$ 0	$ 0	$ 0	$ 0

Net loss per share - Basic and

Net loss per share - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net loss	$ (72,705)	$ (55,987)	$ (53,344)	$ (39,659)	$ (31,083)	$ (25,831)	$ (182,036)	$ (96,573)	$ (151,759)	$ (112,033)
Denominator:
Weighted average common shares outstanding, basic	69,442,136			55,613,120			65,982,798	51,506,766
Weighted average common shares outstanding, diluted	69,442,136			55,613,120			65,982,798	51,506,766
Net loss per share, basic	$ (1.05)			$ (0.71)			$ (2.76)	$ (1.87)
Net loss per share, diluted	$ (1.05)			$ (0.71)			$ (2.76)	$ (1.87)

Net loss per share - Anti-Dilut

Net loss per share - Anti-Diluted (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings per share, total	8,108,505	6,076,697	8,108,505	6,076,697
Options to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings per share, total	7,296,394	5,750,601	7,296,394	5,750,601
Unvested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings per share, total	536,717	142,498	536,717	142,498
Warrants to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings per share, total	64,257	45,898	64,257	45,898
Warrants Available for Future Grant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from the calculation of diluted earnings per share, total	211,137	137,700	211,137	137,700

Commitments and contingencies_2

Commitments and contingencies (Details) $ in Thousands	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jul. 10, 2020 ft²	Feb. 29, 2020 USD ($)
Lease agreement term				7 years
Square feet of office | ft²			6,647
Minimum payments during the term				$ 2,300
Non-cancelable purchase and other commitments with contract research organizations and contract manufacturing organizations	$ 26,647
Total lease liability	888
Operating lease liability, noncurrent	$ 605	$ 819
Accounting Standards Update 2016-13 [Member]
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Operating lease liability, noncurrent, Prepaid Expense and Other Assets, Current
Short-term Liabilities	$ 283

Commitments and contingencies -

Commitments and contingencies - Maturities Of Operating Leases (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2024	$ 84
2025	341
2026	351
2027	208
Total future minimum lease payments	984
Less imputed interest	(96)
Present value of operating lease liabilities	$ 888

Commitments and contingencies_3

Commitments and contingencies - Components of operating lease expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating lease expense:
Total operating lease cost	$ 131	$ 125	$ 409	$ 395
Other information:
Cash paid for amounts included in the measurement of operating lease liability	$ 84	$ 81	$ 247	$ 240
Weighted average remaining lease term (years)	2 years 9 months 18 days	3 years 9 months 18 days	2 years 9 months 18 days	3 years 9 months 18 days
Weighted average discount rate	7.60%	7.60%	7.60%	7.60%
General and administrative expense
Operating lease expense:
Operating lease cost	$ 81	$ 81	$ 243	$ 243
Short-term lease cost	36	36	126	125
Variable operating lease cost	$ 14	$ 8	$ 40	$ 27