Athira Pharma (ATHA) 10-K27 Feb 252024 FY Annual reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2024	Feb. 24, 2025	Jun. 28, 2024
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Entity Registrant Name	Athira Pharma, Inc.
Entity Central Index Key	0001620463
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-3368487
Document Period End Date	Dec. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Trading Symbol	ATHA
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity File Number	001-39503
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Address Address Line1	18706 North Creek Parkway,
Entity Address Address Line2	Suite 104
Entity Address City Or Town	Bothell,
Entity Address State Or Province	WA
Entity Address Postal Zip Code	98011
City Area Code	425
Local Phone Number	620-8501
Document Annual Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Common Stock, Shares Outstanding		39,042,445
Entity Public Float			$ 86
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the definitive proxy statement to be delivered to stockholders in connection with the 2025 annual meeting of stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K. Such proxy statement will be filed with the Securities and Exchange Commission not later than 120 days following the end of the Registrant’s fiscal year ended December 31, 2024.
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Seattle, Washington
Auditor Opinion [Text Block]	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of Athira Pharma, Inc. (the Company) as of December 31, 2024 and 2023, the related consolidated statements of operations and comprehensive loss, stockholders’ equity and cash flows for each of the two years in the period ended December 31, 2024, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2024, in conformity with U.S. generally accepted accounting principles.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 48,438	$ 90,584
Short-term investments	2,837	56,835
Prepaid expenses and other current assets	3,566	5,682
Insurance recovery receivable related to legal settlement (Note 7)		1,628
Total current assets	54,841	154,729
Restricted cash	631	631
Property and equipment, net	2,444	3,388
Operating lease right-of-use asset	808	1,049
Other long-term assets	55	448
Total assets	58,779	160,245
Current liabilities:
Accounts payable	319	129
Accrued liabilities	12,402	18,343
Accrued legal settlement (Note 7)		10,000
Current operating lease liability	414	368
Total current liabilities	13,135	28,840
Operating lease liability, less current portion	803	1,217
Total liabilities	13,938	30,057
Stockholders' equity:
Common stock, $0.0001 par value; 900,000,000 shares authorized at December 31, 2024 and December 31, 2023, respectively; 39,040,945 and 38,172,603 shares issued and outstanding at December 31, 2024 and December 31, 2023, respectively	4	4
Additional paid-in capital	450,982	439,739
Accumulated other comprehensive income (loss)	1	(349)
Accumulated deficit	(406,146)	(309,206)
Total stockholders' equity	44,841	130,188
Total liabilities and stockholders' equity	$ 58,779	$ 160,245

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	39,040,945	38,172,603
Common stock, shares outstanding	39,040,945	38,172,603

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Operating expenses:
Research and development	$ 70,682	$ 93,790
General and administrative	26,093	33,304
Legal expense	4,127
Insurance recovery related to legal settlement		(1,628)
Total operating expenses	100,902	125,466
Loss from operations	(100,902)	(125,466)
Grant income		157
Other income, net	3,962	7,637
Net loss	(96,940)	(117,672)
Unrealized gain on available-for-sale securities	350	1,607
Comprehensive loss attributable to common stockholders	$ (96,590)	$ (116,065)
Net loss per share attributable to common stockholders, basic	$ (2.52)	$ (3.09)
Net loss per share attributable to common stockholders, diluted	$ (2.52)	$ (3.09)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic	38,480,875	38,020,182
Weighted-average shares used in computing net loss per share attributable to common stockholders, diluted	38,480,875	38,020,182

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2022	$ 235,137	$ 4	$ 428,623	$ (1,956)	$ (191,534)
Beginning balance, shares at Dec. 31, 2022		37,877,387
Issuance of common stock upon exercise of common stock options	167		167
Issuance of common stock upon exercise of common stock options, shares		128,534
Issuance of common stock under employee stock purchase plan	326		326
Issuance of common stock under employee stock purchase plan, shares		166,682
Stock-based compensation	10,623		10,623
Unrealized gain on available-for-sale securities	1,607			1,607
Net loss	(117,672)				(117,672)
Ending balance at Dec. 31, 2023	130,188	$ 4	439,739	(349)	(309,206)
Ending balance, shares at Dec. 31, 2023		38,172,603
Issuance of common stock upon exercise of common stock options	$ 12		12
Issuance of common stock upon exercise of common stock options, shares	75,660	75,660
Issuance of common stock upon vesting of restricted stock units, shares		620,668
Issuance of common stock under employee stock purchase plan	$ 182		182
Issuance of common stock under employee stock purchase plan, shares		172,014
Stock-based compensation	11,049		11,049
Unrealized gain on available-for-sale securities	350			350
Net loss	(96,940)				(96,940)
Ending balance at Dec. 31, 2024	$ 44,841	$ 4	$ 450,982	$ 1	$ (406,146)
Ending balance, shares at Dec. 31, 2024		39,040,945

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Operating activities
Net loss	$ (96,940,000)	$ (117,672,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	11,049,000	10,623,000
Depreciation expense	970,000	969,000
Non-cash lease expense	241,000	214,000
Amortization of premiums and accretion of discounts on available-for-sale securities, net	(515,000)	(1,414,000)
Loss on disposal of equipment	7,000
Changes in operating assets and liabilities:
Unbilled grant receivable		1,227,000
Prepaid expenses and other current and long-term assets, net	2,509,000	(113,000)
Insurance recovery receivable related to legal settlement	1,628,000	(1,628,000)
Accounts payable and accrued liabilities	(5,751,000)	7,367,000
Accrued legal settlement	(10,000,000)
Operating lease liability	(368,000)	(326,000)
Net cash used in operating activities	(97,170,000)	(100,753,000)
Investing activities
Purchases of available-for-sale securities	(14,134,000)	(27,671,000)
Maturities of available-for-sale securities	68,997,000	123,064,000
Purchases of property and equipment	(33,000)	(304,000)
Net cash provided by investing activities	54,830,000	95,089,000
Financing activities
Proceeds from exercise of common stock options and issuance of common stock under employee stock purchase plan.	194,000	493,000
Net cash provided by financing activities	194,000	493,000
Net decrease in cash, cash equivalents and restricted cash	(42,146,000)	(5,171,000)
Cash, cash equivalents and restricted cash, beginning of period	91,215,000	96,386,000
Cash, cash equivalents and restricted cash, end of period	$ 49,069,000	$ 91,215,000

Cybersecurity Risk Management,

Cybersecurity Risk Management, Strategy, and Governance	12 Months Ended
Cybersecurity Risk Management, Strategy, and Governance	Dec. 31, 2024
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	Item 1C. Cybersecurity. Cybersecurity Risk Management Strategy We have implemented various processes and policies for identifying, assessing, and managing material risks from cybersecurity threats. Our cybersecurity risk management strategy is designed following the Cybersecurity Framework set by the National Institute of Standard and Technology, or NIST. We assess our information technology, or IT, environment against the NIST Cybersecurity Framework, as well as various cyber-attack vectors, working to identify and remediate risks. We implement reasonable administrative, technical and procedural safeguards to manage cybersecurity risks, for example, by enforcing single sign-on or multi-factor authentication where supported, and the use of mobile device management to secure company resources on employee personal devices. Additionally, we engage third-party cybersecurity experts to assess the security of our network and perform continuous system monitoring, and we engage a third party to perform internal audits of our IT General Controls, or ITGCs. We have implemented certain processes to oversee and identify risks from cybersecurity threats associated with our use of third-party service providers , for example, by evaluating such service providers’ own cybersecurity processes and reviewing available certification and audit reports, including International Organization for Standardization, or ISO, certifications for information security management systems, and System and Organization Controls, or SOC, reports. At this time, we have not experienced cybersecurity incidents, or are aware of any risks from cybersecurity threats, that have materially affected or are reasonably likely to materially affect us, including our business strategy, results of operations, or financial condition. Cybersecurity Governance Board of Directors Our board of directors is responsible for general oversight and regular review of information regarding our risks, including cybersecurity risks. Members of management communicate an overview of our current cybersecurity environment to our board of directors at least annually and provide updates to our board of directors regarding cybersecurity matters periodically throughout the year. Additionally, our third-party auditors inform the audit committee of our board of directors of our ITGC framework and control testing results, which include controls related to cybersecurity risks. Further, management has established cybersecurity incident response processes for escalating the communication of cybersecurity incidents up to the board of directors, as appropriate. Management Material risks from cybersecurity threats are assessed and managed by a dedicated team comprised of internal and external IT professionals experienced in cybersecurity threat risk management , who ultimately report to our senior vice president, finance and accounting. Our senior vice president, finance and accounting has extensive operational and leadership experience overseeing accounting and finance functions at various organizations, including oversight of critical accounting and finance IT systems. Our senior IT consultant has over 20 years of experience with IT and cybersecurity risk management, having served in senior executive-level IT positions at multiple Fortune 500 companies and companies within the life sciences industry. Our team of IT professionals, which continuously monitors our IT environment for cybersecurity threats and incidents, routinely reports on cybersecurity incident prevention, detection, mitigation, and remediation efforts to our senior vice president, finance and accounting and chief compliance officer. Additionally, we have established policies addressing processes for responding to potential cybersecurity incidents, including assessment, communication, and remediation protocols. Our incident response processes further provide for the escalation of cybersecurity incidents to our executive management team and board of directors, as appropriate.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	Board of Directors Our board of directors is responsible for general oversight and regular review of information regarding our risks, including cybersecurity risks. Members of management communicate an overview of our current cybersecurity environment to our board of directors at least annually and provide updates to our board of directors regarding cybersecurity matters periodically throughout the year. Additionally, our third-party auditors inform the audit committee of our board of directors of our ITGC framework and control testing results, which include controls related to cybersecurity risks. Further, management has established cybersecurity incident response processes for escalating the communication of cybersecurity incidents up to the board of directors, as appropriate.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	Our board of directors is responsible for general oversight and regular review of information regarding our risks, including cybersecurity risks.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	Members of management communicate an overview of our current cybersecurity environment to our board of directors at least annually and provide updates to our board of directors regarding cybersecurity matters periodically throughout the year.
Cybersecurity Risk Role of Management [Text Block]	Management Material risks from cybersecurity threats are assessed and managed by a dedicated team comprised of internal and external IT professionals experienced in cybersecurity threat risk management , who ultimately report to our senior vice president, finance and accounting. Our senior vice president, finance and accounting has extensive operational and leadership experience overseeing accounting and finance functions at various organizations, including oversight of critical accounting and finance IT systems. Our senior IT consultant has over 20 years of experience with IT and cybersecurity risk management, having served in senior executive-level IT positions at multiple Fortune 500 companies and companies within the life sciences industry. Our team of IT professionals, which continuously monitors our IT environment for cybersecurity threats and incidents, routinely reports on cybersecurity incident prevention, detection, mitigation, and remediation efforts to our senior vice president, finance and accounting and chief compliance officer. Additionally, we have established policies addressing processes for responding to potential cybersecurity incidents, including assessment, communication, and remediation protocols. Our incident response processes further provide for the escalation of cybersecurity incidents to our executive management team and board of directors, as appropriate.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	Material risks from cybersecurity threats are assessed and managed by a dedicated team comprised of internal and external IT professionals experienced in cybersecurity threat risk management
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Our senior vice president, finance and accounting has extensive operational and leadership experience overseeing accounting and finance functions at various organizations, including oversight of critical accounting and finance IT systems. Our senior IT consultant has over 20 years of experience with IT and cybersecurity risk management, having served in senior executive-level IT positions at multiple Fortune 500 companies and companies within the life sciences industry.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	Our team of IT professionals, which continuously monitors our IT environment for cybersecurity threats and incidents, routinely reports on cybersecurity incident prevention, detection, mitigation, and remediation efforts to our senior vice president, finance and accounting and chief compliance officer.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (96,940)	$ (117,672)

Insider Trading Arrangements

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

Description of Business

Description of Business	12 Months Ended
Description of Business	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	1. Description of Business Organization Athira Pharma, Inc., or the Company, was incorporated as M3 Biotechnology, Inc. in the state of Washington on March 31, 2011 and reincorporated in the state of Delaware on October 27, 2015 . In April 2019, the Company changed its name to Athira Pharma, Inc. The Company currently has office and laboratory space in Bothell, Washington. The Company is a clinical-stage biopharmaceutical company focused on developing small molecules to restore neuronal health and slow neurodegeneration. Liquidity and Capital Resources Since the Company’s inception, it has funded its operations primarily with proceeds from the sale and issuance of common stock, convertible preferred stock, common stock warrants, and convertible notes, and to a lesser extent from grant income and stock option exercises. From the Company’s inception through December 31, 2024, it has raised aggregate net cash proceeds of $ 407.4 million primarily from the issuance of its common stock (excluding option exercises), convertible preferred stock, common stock warrants, and convertible notes. As of December 31, 2024, the Company had cash, cash equivalents and investments of $ 51.3 million. The Company’s net loss for the year ended December 31, 2024 was $ 96.9 million and cash used in operations for the year ended December 31, 2024 was $ 97.2 million. Since the Company’s inception, it has devoted substantially all of its resources to its research and development efforts such as small molecule compound discovery, nonclinical studies and clinical trials, as well as manufacturing activities, establishing and maintaining the Company’s intellectual property portfolio, hiring personnel, raising capital, and providing general and administrative support for these operations. Based upon the Company’s current operating plan, it estimates that its $ 51.3 million of cash, cash equivalents and investments at December 31, 2024 will be sufficient to fund its operating expenses and capital expenditure requirements through at least the next 12 months following the date of the Company’s Annual Report on Form 10-K. Historically, the Company has incurred net losses from continuing operations and negative operating cash flows. The Company has not yet established an ongoing source of revenue sufficient to cover its operating costs; therefore, the Company expects it will need to continue to raise additional capital to accomplish its operating plan. The Company has a sales agreement in place with Cantor Fitzgerald & Co., or Cantor Fitzgerald, and BTIG, LLC, or BTIG, for an “at the market” equity offering facility through which it may offer and sell shares of its common stock equaling an aggregate amount up to $ 75.0 million, subject to applicable limitations on sales pursuant to SEC rules and regulations pertaining to the Company’s Registration Statement on Form S-3. The Company has no t sold any securities pursuant to this ATM offering. Should it be determined to be strategically advantageous, the Company could pursue public and private offerings of its equity securities similar to those the Company has previously completed, debt financings, or other strategic transactions, which could include income from collaboration, licensing or similar arrangements with third parties, or receiving research contributions, or grants.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
Significant Accounting Policies	Dec. 31, 2024
Accounting Policies [Abstract]
Significant Accounting Policies	2 . Significant Accounting Policies Basis of Presentation The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles, or U.S. GAAP. The consolidated financial statements include the operations of Athira Pharma, Inc., and its wholly owned Australian subsidiary. All intercompany balances and transactions have been eliminated upon consolidation. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Estimates include those used for fair value of assets and liabilities, accrued liabilities, valuation allowance for deferred tax assets, and stock-based compensation. Management evaluates related assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers highly liquid investments with original maturities of three months or less to be cash equivalents. Restricted Cash Restricted cash consists of collateral pledged in connection with the Company's corporate credit cards. The table below reconciles the balances of cash and cash equivalents and restricted cash reported on the consolidated balance sheets to the balances of cash, cash equivalents and restricted cash reported on the consolidated statements of cash flows. December 31, 2024 2023 Cash and cash equivalents $ 48,438 $ 90,584 Restricted cash 631 631 Cash, cash equivalents and restricted cash $ 49,069 $ 91,215 Short-term Investments The Company generally invests its excess cash in investment grade short- to intermediate-term fixed income securities. Such investments are included in cash and cash equivalents, and short-term investments on the consolidated balance sheets, classified as available-for-sale, and reported at fair value with unrealized gains and losses included in accumulated other comprehensive income (loss). Amortization and accretion are included in other income, net. Realized gains and losses on the sale of these securities are recognized in other income, net. The Company periodically evaluates whether declines in fair values of its investments below their book value are due to expected credit losses, as well as the Company's ability and intent to hold the investment until a forecasted recovery occurs. Expected credit losses are recorded as an allowance through other income, net. Concentration of Credit Risk The Company is exposed to credit risk from its deposits of cash in excess of amounts insured by the Federal Deposit Insurance Corporation. The Company has not experienced any losses on its deposits of cash since inception. Property and Equipment Property and equipment consist of computer equipment, computer software, laboratory equipment, leasehold improvements and furniture and office equipment. Property and equipment, excluding leasehold improvements, are recorded at cost and depreciation is recognized using the straight-line method based on estimated useful life, generally three to five years . Leasehold improvements are amortized over the shorter of their useful life or the remaining lease term. Maintenance and repairs are charged to expense as incurred, and costs of improvements are capitalized. The Company reviews long-lived assets for impairment whenever events or circumstances indicate the carrying amount of an asset group may not be recoverable. Should an impairment exist, the impairment loss would be measured based on the excess of the asset's carrying amount over its fair value. Gains and losses from asset disposals and impairment losses are classified within the consolidated statements of operations and comprehensive loss in accordance with the use of the asset. There were no impairment losses in the years ended December 31, 2024 and 2023 as there have been no events warranting an impairment analysis. Fair Value Measurements The carrying amounts of certain financial instruments, including cash, cash equivalents, restricted cash, investments, accounts payable and accrued expenses approximate their fair values due to the short-term nature of those amounts. Grant Income In December 2020, the Company accepted a grant from the National Institute on Aging, or the NIA, of the National Institutes of Health, or the NIH, to support its ACT-AD Phase 2 clinical trial for fosgonimeton (then-named ATH-1017), the Company’s lead therapeutic candidate being developed for the treatment of individuals with mild-to-moderate Alzheimer’s disease. The Company recognizes income related to the NIH grant in the accompanying consolidated statements of operations and comprehensive loss as qualifying expenses under the grant agreement are incurred. As of December 31, 2024, the Company has recognized aggregate grant income of $ 15.2 million in connection with the NIH grant, equal to the total grant amount approved. The Company will no t recognize any additional grant income in connection with the NIH grant in the future. During the year ended December 31, 2023, the Company recognized grant income of $ 0.2 million, and received cash of $ 1.4 million, in connection with the NIH grant. There was no grant income recognized or cash received in connection with the NIH grant during the year ended December 31, 2024. Research and Development Expenses Research and development expenses consist primarily of direct and indirect costs incurred for research activities, including development of the pipeline from the Company’s drug discovery efforts and the development of its drug candidates. Direct costs include laboratory materials and supplies, contracted research and manufacturing, clinical trial costs, consulting fees, and other expenses incurred to sustain the Company’s research and development program. Indirect costs include personnel-related expenses, consisting of employee salaries, related benefits, and stock-based compensation expense for employees engaged in research and development activities, and facilities and other expenses consisting of direct and allocated expenses for rent and depreciation and lab consumables. Research and development costs are expensed as incurred. In-licensing fees and other costs to acquire technologies used in research and development that have not yet received regulatory approval and that are not expected to have an alternative future use are expensed when incurred. Non-refundable advance payments for goods and services that will be used over time for research and development are capitalized and recognized as goods are delivered or as the related services are performed. The Company estimates the period over which such services will be performed and the level of effort to be expended in each period. If actual timing of performance or the level of effort varies from the estimate, the Company adjusts the amounts recorded accordingly. The Company has not experienced any material differences between accrued or prepaid costs and actual costs since inception. General and Administrative Expenses General and administrative expenses consist primarily of personnel-related costs, consisting of employee salaries, related benefits, and stock-based compensation expense for employees in the executive, legal, finance and accounting, human resources, and other administrative functions. General and administrative expenses also include third-party costs such as legal costs, insurance costs, accounting, auditing and tax related fees, consulting fees and facilities and other expenses not otherwise included as research and development expenses. General and administrative costs are expensed as incurred. Leases The Company adopted Accounting Standards Codification, or ASC, Topic 842 – Leases effective January 1, 2020. The Company determines if an arrangement contains a lease at inception. The Company performed an evaluation of contracts in accordance with ASC 842 and has determined it has an operating lease agreement for the laboratory and office facilities that the Company occupies. Operating lease right-of-use, or ROU, assets and operating lease liabilities are recognized at the date the underlying asset becomes available for the Company’s use. Operating lease liabilities are based on the present value of the future minimum lease payments over the lease term. ROU assets are measured at the amount of the lease liability, adjusted for any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. As the Company’s leases generally do not provide an implicit interest rate, the present value of the future minimum lease payments is determined using the Company’s incremental borrowing rate. This rate is an estimate of the collateralized borrowing rate the Company would incur on its future lease payments over a similar term and is based on the information available to the Company at the lease commencement date. The Company’s leases contain options to extend the leases; lease terms are adjusted for these options only when it is reasonably certain the Company will exercise these options. The Company’s lease agreements do not contain residual value guarantees or covenants. The Company has made a policy election regarding its real estate leases not to separate non-lease components from lease components, to the extent they are fixed. Non-lease components that are not fixed are expensed as incurred as variable lease expense. The Company’s leases include variable non-lease components, such as common-area maintenance costs. The Company has elected not to record on the balance sheet a lease that has a lease term of 12 months or less and does not contain a purchase option that the Company is reasonably certain to exercise. The Company accounts for leases with initial terms of 12 months or less as operating expenses on a straight-line basis over the lease term. Lease expense is recognized within operating expenses on a straight-line basis over the terms of the leases. Incentives granted under the Company’s facilities lease, including rent holidays, are recognized as adjustments to lease expense on a straight-line basis over the term of the lease. Stock-based Compensation The Company measures compensation expense for all stock-based payments to employees, officers and directors based on the estimated fair value of the award at the grant date. For stock options, the Company estimates the grant date fair value of each option award using the Black-Scholes option-pricing model. The grant date fair value of restricted stock units is based upon the fair market value of the Company’s common stock based on its closing price as reported on the date of grant on the Nasdaq Global Select Market. Compensation expense is recognized over the requisite service period on a straight-line basis. Forfeitures are recognized as they occur. The Company records compensation expense for stock option and restricted stock unit grants subject to performance-based milestone vesting over the remaining implicit service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the relative satisfaction of the performance conditions as of the reporting date. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. In assessing the Company’s ability to realize deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences are deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future income, tax planning strategies in making this assessment. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company accrues interest and penalties related to unrecognized tax benefits in its provision for incomes taxes. Comprehensive Loss Attributable to Common Stockholders Comprehensive loss attributable to common stockholders consists of net loss and other gains and losses affecting stockholders’ equity that, under U.S. GAAP, are excluded from net loss. The Company’s comprehensive loss attributable to common stockholders is comprised of net loss and unrealized gains and losses on available-for-sale securities. Net Loss Per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration of potentially dilutive securities. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders since the effect of potentially dilutive securities is anti-dilutive given the net loss of the Company. Foreign Currency Transaction Remeasurement Adjustments Monetary assets and liabilities denominated in foreign currencies were translated into U.S. dollars, the reporting currency, at the exchange rate prevailing at the balance sheet date. Income and expenses denominated in foreign currencies were translated into U.S. dollars at the average exchange rate for the period and the transaction remeasurement adjustments are reported within other income, net in the consolidated statement of operations and comprehensive loss. The functional currency of the Company’s Australian subsidiary is the U.S. dollar. Corporate Restructuring On September 15, 2024, the Company committed to a workforce reduction that resulted in the termination of approximately 70 % of the Company’s workforce, or the Restructuring. In connection with the Restructuring, the Company incurred costs of $ 2.9 million, consisting primarily of cash severance costs and termination benefits, which the Company recognized during the year ended December 31, 2024. The Company substantially completed the Restructuring by December 31, 2024. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012, or JOBS Act. Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it is (1) no longer an emerging growth company and (2) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act, unless early adoption is permitted. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recent Accounting Pronouncements In November 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2023-07, Segment Reporting (Topic 280), Improvements to Reportable Segment Disclosures to improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses on an interim and annual basis. All disclosure requirements of ASU 2023-07 are required for entities with a single reportable segment. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods for the fiscal years beginning after December 15, 2024, and should be applied on a retrospective basis to all periods presented. Early adoption is permitted. The Company adopted the guidance in the fiscal year beginning January 1, 2024 , including the additional required disclosures in Note 6. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740) - Improvements to Income Tax Disclosures. The ASU requires that an entity disclose specific categories in the effective tax rate reconciliation as well as provide additional information for reconciling items that meet a quantitative threshold. Further, the ASU requires certain disclosures of state versus federal income tax expense and taxes paid. The amendments in this ASU are required to be adopted for fiscal years beginning after December 15, 2024. Early adoption is permitted and the amendments should be applied on a prospective basis. The Company does not expect the adoption of this new guidance to have a material impact on its consolidated financial statements and is currently evaluating the effect of adopting the ASU on its disclosures .

Fair Value

Fair Value	12 Months Ended
Fair Value	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value	3 . Fair Value The Company has certain assets and liabilities that are measured at fair value on a recurring basis according to a fair value hierarchy that prioritizes the inputs, assumptions and valuation techniques used to measure fair value. The three levels of the fair value hierarchy are: Level 1 —Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2 —Quoted prices in markets that are not active or financial instruments for which all significant inputs are observable, either directly or indirectly. Level 3 —Inputs are generally unobservable and reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. The fair values are determined using model-based techniques, including probability-based simulation methodologies. The determination of a financial instrument’s level within the fair value hierarchy is based on an assessment of the lowest level of any input that is significant to the fair value measurement. The Company considers observable data to be market data, which is readily available, regularly distributed or updated, reliable and verifiable, not proprietary, and provided by independent sources that are actively involved in the relevant market. The following tables reflect the Company’s financial asset balances measured at fair value on a recurring basis (in thousands): December 31, 2024 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 30 $ — $ — $ 30 U.S. government debt and agency 2 $ 10,297 $ 2 $ — $ 10,299 Commercial paper 2 19,394 — ( 1 ) 19,393 Total cash equivalents $ 29,721 $ 2 $ ( 1 ) $ 29,722 Short-term investments: Commercial paper 2 1,445 — — 1,445 U.S. government debt and agency 2 1,392 — — 1,392 Total short-term investments $ 2,837 $ — $ — $ 2,837 December 31, 2023 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 63 $ — $ — $ 63 Commercial paper 2 59,227 — ( 30 ) 59,197 Total cash equivalents $ 59,290 $ — $ ( 30 ) $ 59,260 Short-term investments: Commercial paper 2 6,431 — ( 4 ) 6,427 U.S. government debt and agency 2 50,723 — ( 315 ) 50,408 Total short-term investments $ 57,154 $ — $ ( 319 ) $ 56,835 All the commercial paper and U.S. government debt and agency securities designated as short-term investments have an effective maturity date that is equal to or less than one year from the respective balance sheet date.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
Property and Equipment, Net	Dec. 31, 2024
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	4. Property and Equipment, Net Property and equipment consisted of the following (in thousands): December 31, 2024 2023 Lab equipment $ 705 $ 688 Office furniture, fixtures, and 712 712 Leasehold improvement 4,322 4,322 Property and equipment, at cost 5,739 5,722 Less: accumulated depreciation ( 3,295 ) ( 2,334 ) Property and equipment, net $ 2,444 $ 3,388 Depreciation expense was $ 970,000 and $ 969,000 for the years ended December 31, 2024 and 2023, respectively.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
Accrued Liabilities	Dec. 31, 2024
Payables and Accruals [Abstract]
Accrued Liabilities	5 . Accrued Liabilities Accrued liabilities consisted of the following (in thousands): December 31, 2024 2023 Research and development $ 3,424 $ 11,916 Employee compensation and benefits 2,990 4,545 Legal expense 4,127 — Professional services and other 1,861 1,882 Total accrued liabilities $ 12,402 $ 18,343

Segment Reporting

Segment Reporting	12 Months Ended
Segment Reporting	Dec. 31, 2024
Segment Reporting [Abstract]
Segment Reporting	6. Segment Reporting The Company operates as a single operating segment, which is the business of developing and commercializing therapeutics. The Company’s chief operating decision maker, or CODM, its chief executive officer , reviews financial information on an aggregate basis for the purpose of allocating resources and assessing performance. When deciding how to allocate resources, the CODM reviews the financial results of the Company's drug candidate programs. The measure of segment assets is reported on the consolidated balance sheet as total assets. The table below is a summary of the segment profit or loss, including significant segment expenses (in thousands): Year Ended December 31, 2024 2023 Research and development expenses: Fosgonimeton (ATH-1017) $ 41,510 $ 66,524 ATH-1105 8,567 $ — ATH-1020 495 704 Preclinical programs and other costs 3,390 8,219 Personnel-related costs, excluding stock- 12,289 13,952 Total research and development expenses 66,251 89,399 General and administrative expenses 22,631 24,475 Other segment expenses (a) 12,020 11,592 Total operating expenses 100,902 125,466 Loss from operations ( 100,902 ) ( 125,466 ) Grant income — 157 Other income, net 3,962 7,637 Net loss $ ( 96,940 ) $ ( 117,672 ) (a) Other segment expenses includes stock-based compensation and depreciation expenses.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Legal Proceedings From time to time, the Company is subject to various legal proceedings or claims that arise in the ordinary course of business. The Company accrues a liability when the Company's management believes that it is both probable that a liability has been incurred and the amount of loss can be reasonably estimated. The following is a brief description of the more significant legal proceedings. Securities Class Actions Starting in June 2021, putative securities class action lawsuits were filed in the U.S. District Court for the Western District of Washington against the Company and certain of its current and former members of management and the board of directors. After these lawsuits were consolidated and lead plaintiffs were appointed to represent the putative class, lead plaintiffs filed a consolidated amended complaint on January 7, 2022, which asserted violations of Sections 10(b) and 20(a) of the Exchange Act and SEC Rule 10b-5 and Sections 11, 12, and 15 of the Securities Act. The consolidated amended complaint alleged that the IPO and SPO registration statements and/or other public statements were materially false and misleading because they omitted to state that certain of the Company's former CEO’s published doctoral research papers at WSU contained allegedly improperly altered images. Lead plaintiffs sought unspecified compensatory damages, as well as equitable and injunctive relief on behalf of themselves and the purported class. On July 29, 2022, the court issued an order granting in part and denying in part the defendants’ motion to dismiss. The order dismissed the Section 10(b) and Section 20(a) claims arising under the Exchange Act, dismissed the Section 11 claim arising under the Securities Act as to all defendants other than the Company and its former CEO, dismissed the Section 12(a)(2) claim arising under the Securities Act as to the lead plaintiffs, and dismissed the Section 15 claim arising under the Securities Act against all defendants other than the Company's former CEO. On November 4, 2022, the Company and its former CEO filed their individual answers to the consolidated amended complaint. In mid-November 2022, the parties began conducting fact discovery. On March 29, 2024, following a mediation and the parties’ agreement in the fourth quarter of 2022 to settle the securities class action for $ 10 million subject to the court’s approval, the court entered an order preliminarily approving a settlement of the securities class action. On November 1, 2024, following class notice and a final approval hearing, the court entered a final written judgment and order granting final approval of the settlement and closed the case. As a result of the foregoing, the Company recorded a legal settlement expense of $ 10.0 million in operating expenses in the fourth quarter of 2022. An accrued liability of $ 10.0 million was recorded on the accompanying condensed consolidated balance sheets as of December 31, 2023. Additionally, the Company recorded an insurance recovery of $ 1.6 million in operating expenses in the fourth quarter of 2023 and an insurance recovery receivable of $ 1.6 million on the accompanying condensed consolidated balance sheets as of December 31, 2023. This insurance recovery represents the amount of the settlement covered by the Company's insurers. The Company and its insurance providers paid the settlement fee during 2024 and no further liability exists following the court granting final approval of the settlement and closing the case in November 2024. Shareholder Derivative Actions Starting in April 2022, shareholder derivative actions were filed in the U.S. District Court for the Western District of Washington against certain current and former members of the Company’s board of directors. The derivative complaints alleged that the Company’s board of directors breached its fiduciary duties by failing to prevent alleged misstatements in the Company’s public filings, failing to discover altered images in certain research papers, and failing to take appropriate action. The derivative complaints asserted claims for violations of Section 14(a) of the Exchange Act as well as claims for breach of fiduciary duty, contribution and indemnification, aiding and abetting, and waste of corporate assets. On May 26, 2022, the court issued an order consolidating the derivative cases and staying them until further order of the court. On March 18, 2024, following a mediation and the parties entering into a stipulation of settlement to settle the consolidated derivative action for certain corporate governance reforms and the payment of a fee and expense award to plaintiffs’ counsel, plaintiffs filed an unopposed motion for preliminary approval of a settlement of the derivative action. On July 18, 2024, the court entered an order and judgment granting plaintiffs’ motion for final approval of derivative settlement, finding the settlement to be fair, reasonable, and adequate to the settling parties and the Company’s shareholders, and dismissing the derivative action with prejudice. The Company paid the fee and expense award related to this shareholder derivative action settlement during the third quarter of 2024. Government Investigation In November 2022, the Company received a Civil Investigative Demand from the Civil Division of the Department of Justice, or the Demand. The Demand sought documents and information relating to the Company’s relationship with WSU, certain of its grant applications in 2016 and 2019 with the NIH, and the Company’s receipt of an NIH grant in 2020. The Company cooperated with the Department of Justice with respect to the Demand. In September 2024, the Company reached an agreement in principle (subject to approvals within the Department of Justice and the Office of Inspector General of the U.S. Department of Health and Humans Service) to settle the Department of Justice’s claims, including alleged violations of the False Claims Act in connection with the NIH grant applications and the Company’s receipt of an NIH grant in connection with one of those applications. This agreement also included the same claims alleged in a confidential, sealed qui tam complaint. On December 31, 2024, the Company entered into a settlement agreement with the Department of Justice, OIG-HHS, and the qui tam lawsuit relator in which the Company agreed to pay approximately $ 4.1 million. The Company recorded a legal expense of $ 4.1 million based on developments in the third quarter of 2024 and a corresponding accrued liability on the accompanying consolidated balance sheets as of December 31, 2024. The Company paid the $ 4.1 million settlement in January 2025. Indemnifications In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. To date the Company has not incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. The Company enters into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by Delaware corporate law. The Company currently has directors’ and officers’ insurance coverage that reduces its exposure and enables the Company to recover a portion of any future amounts paid. Operating Leases The Company has operating leases for laboratory and office facilities in Bothell, Washington that expire in August 2027 . The initial terms of the leases range from 6.3 to 7 years and the Company has options to extend the leases for an additional five years that it is not reasonably certain to exercise . As of December 31, 2024, the Company was not party to any finance leases. The following table reconciles the Company’s undiscounted operating lease cash flows to its operating lease liability (in thousands): December 31, 2025 494 2026 509 Thereafter 346 Total undiscounted lease payments 1,349 Present value adjustment for minimum lease ( 132 ) Net lease liability $ 1,217 The weighted average remaining lease term and the weighted average discount rate used to determine the operating lease liability were as follows: December 31, Weighted average remaining lease term (years) 2.7 Weighted average discount rate 8.1 % Operating lease expense was $ 353,000 and $ 353,000 for the years ended December 31, 2024 and 2023, respectively. Separately, variable lease expense was $ 149,000 and $ 186,000 for operating leases during the years ended December 31, 2024 and 2023, respectively.

Common Stock

Common Stock	12 Months Ended
Common Stock	Dec. 31, 2024
Equity [Abstract]
Common Stock	8. Common Stock Each share of common stock has the right to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and if declared by the Company’s board of directors, subject to the prior rights of holders of all classes of stock outstanding having priority rights as to dividends. No cash dividends have been declared by the board of directors from inception. The Company has reserved the following shares of common stock for future issuance, on an as-converted basis, as follows: December 31, 2024 2023 Shares issuable upon the exercise of outstanding 10,234,971 7,130,956 Shares available for future grant under the 2020 1,666,381 3,158,094 Shares available for future grant under the 1,338,444 1,128,732 Shares available for future grant under the 2024 350,000 — Total 13,589,796 11,417,782 The Company’s 2020 Equity Incentive Plan, or the 2020 Plan, provides for annual increases in the number of shares that may be issued under the 2020 Plan on January 1, 2021 and each subsequent January 1, thereafter, by a number of shares equal to the least of (1) 3,230,000 shares, (2) 5 % of the number of shares of common stock issued and outstanding on the immediately preceding December 31, and (3) an amount determined by the Company’s board of directors. The Company’s 2020 Employee Stock Purchase Plan, or the ESPP, provides for annual increases in the number of shares that may be issued under the ESPP on January 1, 2021 and each subsequent January 1, thereafter, by a number of shares equal to the least of (1) 646,000 shares, (2) 1 % of the number of shares of common stock issued and outstanding on the immediately preceding December 31, and (3) an amount determined by the Company’s board of directors . Effective January 1, 2024, the Company’s 2020 Plan and ESPP reserves increased by 1,908,630 shares and 381,726 shares, respectively . In February 2024, the board of directors adopted the Athira Pharma, Inc. 2024 Inducement Equity Incentive Plan, or the 2024 Inducement Plan, and, subject to the adjustment provisions of the 2024 Inducement Plan, reserved 750,000 shares of the Company's common stock for issuance pursuant to equity awards granted under the 2024 Inducement Plan . Effective January 1, 2025, the Company’s 2020 Plan and ESPP reserves increased by 1,952,047 shares and 390,409 shares, respectively.

Stock-based Compensation

Stock-based Compensation	12 Months Ended
Stock-based Compensation	Dec. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	9. Stock-based Compensation Stock‑based compensation expense recognized was as follows (in thousands): Year Ended December 31, 2024 2023 Research and development $ 4,043 $ 4,003 General and administrative 7,006 6,620 Total stock-based compensation expense $ 11,049 $ 10,623 Valuation Assumptions The fair value of stock options was determined using the Black-Scholes option-pricing model and the assumptions below. Each of these inputs is subjective and generally required significant judgment. • Fair Value of Common Stock —The fair value of each share of common stock is based on the closing price of the Company’s common stock on the date of grant, or other relevant determination date, as reported on The Nasdaq Global Select Market. • Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the option. • Expected Volatility —Because the Company was previously privately held and did not have any trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded life sciences companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on the similar size, stage in life cycle or area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. • Expected Term —The expected term represents the period that the stock-based awards are expected to be outstanding and is determined using the simplified method (based on the midpoint between the vesting date and the end of the contractual term) as the Company has limited history of relevant stock option exercise activity. • Expected Dividend Yield —The Company has never paid dividends on its common stock and has no plans to pay dividends going forward. Therefore, it used an expected dividend yield of zero . The fair value of each stock option was estimated using the Black‑Scholes option‑pricing model with the following weighted-average assumptions: Year Ended December 31, 2024 2023 Risk-free interest rate 4.13 % 3.54 % Expected volatility 97.21 % 99.18 % Expected term (in years) 5.88 5.84 Expected dividend yield — — The grant date fair value of restricted stock units is based upon the fair market value of the Company’s common stock based on its closing price as reported on the date of grant on the Nasdaq Global Select Market. The fair value of options granted during the years ended December 31, 2024 and 2023 was $ 10.6 million and $ 9.8 million, respectively. The fair value of restricted stock units granted during the year ended December 31, 2024 and 2023 was $ 0.4 million and $ 0.5 million, respectively. Stock Option Activity Changes in shares available for grant under the 2020 Plan and the 2024 Inducement Plan during the year ended December 31, 2024 were as follows: Shares Shares available for grant at December 31, 2023 3,158,094 2020 Plan reserve increase on January 1, 2024 1,908,630 Shares reserved upon adoption of the 750,000 Options and restricted stock units granted ( 5,986,613 ) Options and restricted stock units forfeited, 2,186,270 Shares available for grant at December 31, 2024 2,016,381 A summary of stock option activity under the 2020 Plan and the 2024 Inducement Plan for the year ended December 31, 2024 was as follows: Shares Weighted- Weighted- Aggregate Balance at December 31, 2023 6,820,869 $ 7.97 8.24 $ 387 Granted 5,052,871 2.64 Exercised ( 75,660 ) 0.16 Forfeited/expired ( 2,185,770 ) 4.21 Balance at December 31, 2024 9,612,310 $ 6.08 8.08 $ 130 Expected to vest 4,055,037 $ 3.79 8.82 $ 87 Options exercisable 5,557,273 $ 7.75 7.53 $ 43 The total fair value of options granted that vested during the years ended December 31, 2024 and 2023 was $ 11.0 million and $ 9.8 million, respectively. The aggregate intrinsic value in the table above is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the Company’s common stock underlying all options that were in-the-money at December 31, 2024. The aggregate intrinsic value of options exercised was $ 0.2 million and $ 0.2 million during the year ended December 31, 2024 and 2023, respectively, determined as of the date of option exercise. As of December 31, 2024, there was $ 9.8 million of total unrecognized compensation cost related to non-vested stock options. The Company expects to recognize this cost over a remaining weighted-average period of 1.99 years. The Company utilizes newly issued shares to satisfy option exercises. Stock options outstanding and exercisable under the 2020 Plan and the 2024 Inducement Plan consisted of the following at December 31, 2024: Exercise Price ($) Options Options 0.43 to 0.71 964,067 310,581 1.04 to 4.22 5,771,807 2,834,921 8.93 to 19.94 2,528,788 2,136,223 20.55 to 29.41 347,648 275,548 Total 9,612,310 5,557,273 Restricted Stock Unit Activity A summary of restricted stock unit, or RSU, activity for the year ended December 31, 2024 is as follows: Share Weighted- Non-vested at December 31, 2023 310,087 $ 11.44 Granted 933,742 0.46 Cancelled ( 500 ) 2.51 Vested ( 620,668 ) 5.94 Non-vested at December 31, 2024 622,661 $ 0.46 As of December 31, 2024, there was $ 0.2 million of total unrecognized compensation cost related to non-vested RSUs. The Company expects to recognize this cost over a remaining weighted-average period of 0.77 years. Employee Stock Purchase Plan Under the ESPP, eligible employees can authorize payroll deductions for amounts up to the lesser of 15 % of their qualifying wages or the statutory limit under the U.S. Internal Revenue Code. The ESPP provides for offering periods of six months in duration with one purchase period per offering period beginning May 18 and November 18 of each year. Participants in an offering period will be granted the right to purchase shares of our common stock at a price per share that is 85 % of the lesser of the fair market value of the shares at (1) the first day of the offering period or (2) the end of each purchase period within the offering period. A maximum of 10,000 shares of common stock may be purchased by each participant at the purchase date during the offering period. The fair market value of the ESPP options granted is determined using the Black-Scholes model and is amortized on a straight-line basis. Stock-based compensation expense recognized during the years ended December 31, 2024 and 2023 associated with the ESPP was $ 0.1 million and $ 0.1 million, respectively. During the year ended December 31, 2024, the Company issued 172,014 shares of common stock to employees under the ESPP.

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes Components of Income and Income Tax The Company did not record a provision (benefit) for income taxes for the years ended December 31, 2024 and 2023. Net loss is attributable to the following tax jurisdictions (in thousands): Year Ended December 31, 2024 2023 United States $ ( 96,910 ) $ ( 117,440 ) Foreign ( 30 ) ( 232 ) Net Loss $ ( 96,940 ) $ ( 117,672 ) The provision for income taxes differs from the amount expected by applying the federal statutory rates to the net loss before taxes as follows: Year Ended December 31, 2024 2023 Federal statutory income tax rate 21.0 % 21.0 % State taxes — — Stock-based compensation ( 1.8 ) ( 1.1 ) Non-deductible expenses and others ( 0.9 ) ( 0.1 ) Tax credits 3.1 4.2 Change in valuation allowance ( 21.4 ) ( 24.0 ) Effective income tax rate — % — % Deferred Tax Assets and Liabilities The components of the Company’s deferred tax assets and liabilities were as follows (in thousands): Year Ended December 31, 2024 2023 Deferred tax assets: Net operating loss carryforwards $ 43,414 $ 31,342 Research and development tax credit 12,362 9,327 Accrued liabilities 538 2,828 Stock-based compensation 2,867 2,564 Operating lease liability 256 333 Other 258 180 Capitalized research and development 32,540 25,182 Total deferred tax assets 92,235 71,756 Deferred tax liabilities: Right of use asset ( 170 ) ( 221 ) Prepaid expenses and other ( 82 ) ( 75 ) Investments ( 34 ) ( 214 ) Total deferred tax liabilities ( 286 ) ( 510 ) Less valuation allowance ( 91,949 ) ( 71,246 ) Net deferred tax assets $ — $ — Deferred income taxes reflect temporary differences between the carrying amounts of assets and liabilities for financial reporting and income tax purposes, and operating losses and tax credit carryforwards. The Company considers a number of factors concerning the realizability of its net deferred tax assets, including its history of operating losses, the nature of the deferred tax assets, and the timing, likelihood and amount, if any, of future taxable income during the periods in which those temporary differences and carryforwards become deductible, all of which require significant judgment. As of December 31, 2024, the Company has recorded a full valuation allowance on its net deferred tax assets as the Company has concluded that it is not more likely than not that such losses or credits will be utilized. The valuation allowance increased by $ 20.7 million and $ 28.3 million during 2024 and 2023, respectively. At December 31, 2024, the Company has federal net operating loss and tax credit carryforwards of $ 9.5 million and $ 16.5 million, respectively, which expire over a period of 7 to 13 years. Net operating loss carryforwards of $ 196.0 million were generated after 2017, and therefore do not expire. As of December 31, 2024, the Company also had state net operating loss carryforwards of $ 3.9 million, which expire over a period of 17 to 20 years. Uncertain Tax Positions The Company files federal income tax returns. With few exceptions, the Company is no longer subject to income tax examinations by tax authorities for years prior to 2016. However, to the extent allowed by law, the tax authorities may have the right to examine prior periods where net operating losses or tax credits were generated and carried forward and may make adjustments to the amount of the net operating loss or credit carryforward amount. The Company is not currently under examination in any jurisdiction. A reconciliation of the beginning and ending amount of unrecognized tax benefits for uncertain tax positions were as follows (in thousands): Year Ended December 31, 2024 2023 Beginning balance $ 3,109 $ 1,406 Additions for tax positions taken in prior — 182 Additions for tax positions taken in the current 1,012 1,521 Ending balance $ 4,121 $ 3,109 If the unrecognized tax benefits for uncertain tax positions as of December 31, 2024 are recognized, there will be no impact to the effective tax rate due to the valuation allowance. The Company recognizes interest and penalties related to unrecognized tax benefits within the income tax expense line in the accompanying consolidated financial statements. At December 31, 2024, there were no material interest and penalties on uncertain tax benefits. The Company does not anticipate any significant changes to its unrecognized tax benefits in the next 12 months.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2024
Employee Benefit Plans [Abstract]
Employee Benefit Plans	11. Employee Benefit Plans The Company has a 401(k) Plan for all of its employees. The 401(k) Plan allows eligible employees to defer, at the employee’s discretion, up to 100 % of their pretax compensation up to the Internal Revenue Service annual limit. The Company made matching contributions of $ 0.5 million and $ 0.5 million during the years ended December 31, 2024 and 2023, respectively.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	12 Months Ended
Net Loss Per Share Attributable to Common Stockholders	Dec. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	12. Net Loss Per Share Attributable to Common Stockholders The following outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share attributable to common stockholders for the periods presented because their effect would have been anti-dilutive: Year Ended December 31, 2024 2023 Stock options to purchase common stock 9,612,310 6,820,869 Non-vested Restricted Stock Units 622,661 310,087 Employee stock purchase plan 8,507 3,495 Total 10,243,478 7,134,451

Corporate Restructuring

Corporate Restructuring	12 Months Ended
Corporate Restructuring	Dec. 31, 2024
Restructuring and Related Activities [Abstract]
Corporate Restructuring	13. Corporate Restructuring The Company currently estimates that it will incur costs of approximately $ 2.9 million for termination benefits relating to the Restructuring, substantially all of which the Company recognized during the year ended December 31, 2024. The Company expensed the following costs associated with the termination benefit payments resulting from the Restructuring (in thousands): Year Ended December 31, 2024 Research and development expense 1,495 General and administrative expense 1,392 Total severance expense 2,887 As of December 31, 2024, the accrued liability balance associated with the Restructuring is $ 0.4 million and is included in the accrued expenses line of the accompanying consolidated balance sheet. Cash paid during the year ended December 31, 2024 associated with the termination benefits was $ 2.5 million.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles, or U.S. GAAP. The consolidated financial statements include the operations of Athira Pharma, Inc., and its wholly owned Australian subsidiary. All intercompany balances and transactions have been eliminated upon consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Estimates include those used for fair value of assets and liabilities, accrued liabilities, valuation allowance for deferred tax assets, and stock-based compensation. Management evaluates related assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers highly liquid investments with original maturities of three months or less to be cash equivalents.
Restricted Cash	Restricted Cash Restricted cash consists of collateral pledged in connection with the Company's corporate credit cards. The table below reconciles the balances of cash and cash equivalents and restricted cash reported on the consolidated balance sheets to the balances of cash, cash equivalents and restricted cash reported on the consolidated statements of cash flows. December 31, 2024 2023 Cash and cash equivalents $ 48,438 $ 90,584 Restricted cash 631 631 Cash, cash equivalents and restricted cash $ 49,069 $ 91,215
Short-term Investments	Short-term Investments The Company generally invests its excess cash in investment grade short- to intermediate-term fixed income securities. Such investments are included in cash and cash equivalents, and short-term investments on the consolidated balance sheets, classified as available-for-sale, and reported at fair value with unrealized gains and losses included in accumulated other comprehensive income (loss). Amortization and accretion are included in other income, net. Realized gains and losses on the sale of these securities are recognized in other income, net. The Company periodically evaluates whether declines in fair values of its investments below their book value are due to expected credit losses, as well as the Company's ability and intent to hold the investment until a forecasted recovery occurs. Expected credit losses are recorded as an allowance through other income, net.
Concentration of Credit Risk	Concentration of Credit Risk The Company is exposed to credit risk from its deposits of cash in excess of amounts insured by the Federal Deposit Insurance Corporation. The Company has not experienced any losses on its deposits of cash since inception.
Property and Equipment	Property and Equipment Property and equipment consist of computer equipment, computer software, laboratory equipment, leasehold improvements and furniture and office equipment. Property and equipment, excluding leasehold improvements, are recorded at cost and depreciation is recognized using the straight-line method based on estimated useful life, generally three to five years . Leasehold improvements are amortized over the shorter of their useful life or the remaining lease term. Maintenance and repairs are charged to expense as incurred, and costs of improvements are capitalized. The Company reviews long-lived assets for impairment whenever events or circumstances indicate the carrying amount of an asset group may not be recoverable. Should an impairment exist, the impairment loss would be measured based on the excess of the asset's carrying amount over its fair value. Gains and losses from asset disposals and impairment losses are classified within the consolidated statements of operations and comprehensive loss in accordance with the use of the asset. There were no impairment losses in the years ended December 31, 2024 and 2023 as there have been no events warranting an impairment analysis.
Fair Value Measurements	Fair Value Measurements The carrying amounts of certain financial instruments, including cash, cash equivalents, restricted cash, investments, accounts payable and accrued expenses approximate their fair values due to the short-term nature of those amounts.
Grant Income	Grant Income In December 2020, the Company accepted a grant from the National Institute on Aging, or the NIA, of the National Institutes of Health, or the NIH, to support its ACT-AD Phase 2 clinical trial for fosgonimeton (then-named ATH-1017), the Company’s lead therapeutic candidate being developed for the treatment of individuals with mild-to-moderate Alzheimer’s disease. The Company recognizes income related to the NIH grant in the accompanying consolidated statements of operations and comprehensive loss as qualifying expenses under the grant agreement are incurred. As of December 31, 2024, the Company has recognized aggregate grant income of $ 15.2 million in connection with the NIH grant, equal to the total grant amount approved. The Company will no t recognize any additional grant income in connection with the NIH grant in the future. During the year ended December 31, 2023, the Company recognized grant income of $ 0.2 million, and received cash of $ 1.4 million, in connection with the NIH grant. There was no grant income recognized or cash received in connection with the NIH grant during the year ended December 31, 2024.
Research and Development Expenses	Research and Development Expenses Research and development expenses consist primarily of direct and indirect costs incurred for research activities, including development of the pipeline from the Company’s drug discovery efforts and the development of its drug candidates. Direct costs include laboratory materials and supplies, contracted research and manufacturing, clinical trial costs, consulting fees, and other expenses incurred to sustain the Company’s research and development program. Indirect costs include personnel-related expenses, consisting of employee salaries, related benefits, and stock-based compensation expense for employees engaged in research and development activities, and facilities and other expenses consisting of direct and allocated expenses for rent and depreciation and lab consumables. Research and development costs are expensed as incurred. In-licensing fees and other costs to acquire technologies used in research and development that have not yet received regulatory approval and that are not expected to have an alternative future use are expensed when incurred. Non-refundable advance payments for goods and services that will be used over time for research and development are capitalized and recognized as goods are delivered or as the related services are performed. The Company estimates the period over which such services will be performed and the level of effort to be expended in each period. If actual timing of performance or the level of effort varies from the estimate, the Company adjusts the amounts recorded accordingly. The Company has not experienced any material differences between accrued or prepaid costs and actual costs since inception.
General and Administrative Expenses	General and Administrative Expenses General and administrative expenses consist primarily of personnel-related costs, consisting of employee salaries, related benefits, and stock-based compensation expense for employees in the executive, legal, finance and accounting, human resources, and other administrative functions. General and administrative expenses also include third-party costs such as legal costs, insurance costs, accounting, auditing and tax related fees, consulting fees and facilities and other expenses not otherwise included as research and development expenses. General and administrative costs are expensed as incurred.
Leases	Leases The Company adopted Accounting Standards Codification, or ASC, Topic 842 – Leases effective January 1, 2020. The Company determines if an arrangement contains a lease at inception. The Company performed an evaluation of contracts in accordance with ASC 842 and has determined it has an operating lease agreement for the laboratory and office facilities that the Company occupies. Operating lease right-of-use, or ROU, assets and operating lease liabilities are recognized at the date the underlying asset becomes available for the Company’s use. Operating lease liabilities are based on the present value of the future minimum lease payments over the lease term. ROU assets are measured at the amount of the lease liability, adjusted for any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. As the Company’s leases generally do not provide an implicit interest rate, the present value of the future minimum lease payments is determined using the Company’s incremental borrowing rate. This rate is an estimate of the collateralized borrowing rate the Company would incur on its future lease payments over a similar term and is based on the information available to the Company at the lease commencement date. The Company’s leases contain options to extend the leases; lease terms are adjusted for these options only when it is reasonably certain the Company will exercise these options. The Company’s lease agreements do not contain residual value guarantees or covenants. The Company has made a policy election regarding its real estate leases not to separate non-lease components from lease components, to the extent they are fixed. Non-lease components that are not fixed are expensed as incurred as variable lease expense. The Company’s leases include variable non-lease components, such as common-area maintenance costs. The Company has elected not to record on the balance sheet a lease that has a lease term of 12 months or less and does not contain a purchase option that the Company is reasonably certain to exercise. The Company accounts for leases with initial terms of 12 months or less as operating expenses on a straight-line basis over the lease term. Lease expense is recognized within operating expenses on a straight-line basis over the terms of the leases. Incentives granted under the Company’s facilities lease, including rent holidays, are recognized as adjustments to lease expense on a straight-line basis over the term of the lease.
Stock-based Compensation	Stock-based Compensation The Company measures compensation expense for all stock-based payments to employees, officers and directors based on the estimated fair value of the award at the grant date. For stock options, the Company estimates the grant date fair value of each option award using the Black-Scholes option-pricing model. The grant date fair value of restricted stock units is based upon the fair market value of the Company’s common stock based on its closing price as reported on the date of grant on the Nasdaq Global Select Market. Compensation expense is recognized over the requisite service period on a straight-line basis. Forfeitures are recognized as they occur. The Company records compensation expense for stock option and restricted stock unit grants subject to performance-based milestone vesting over the remaining implicit service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the relative satisfaction of the performance conditions as of the reporting date.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. In assessing the Company’s ability to realize deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences are deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future income, tax planning strategies in making this assessment. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company accrues interest and penalties related to unrecognized tax benefits in its provision for incomes taxes.
Comprehensive Loss Attributable to Common Stockholders	Comprehensive Loss Attributable to Common Stockholders Comprehensive loss attributable to common stockholders consists of net loss and other gains and losses affecting stockholders’ equity that, under U.S. GAAP, are excluded from net loss. The Company’s comprehensive loss attributable to common stockholders is comprised of net loss and unrealized gains and losses on available-for-sale securities.
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration of potentially dilutive securities. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders since the effect of potentially dilutive securities is anti-dilutive given the net loss of the Company.
Foreign Currency Transaction Remeasurement Adjustments	Foreign Currency Transaction Remeasurement Adjustments Monetary assets and liabilities denominated in foreign currencies were translated into U.S. dollars, the reporting currency, at the exchange rate prevailing at the balance sheet date. Income and expenses denominated in foreign currencies were translated into U.S. dollars at the average exchange rate for the period and the transaction remeasurement adjustments are reported within other income, net in the consolidated statement of operations and comprehensive loss. The functional currency of the Company’s Australian subsidiary is the U.S. dollar.
Corporate Restructuring	Corporate Restructuring On September 15, 2024, the Company committed to a workforce reduction that resulted in the termination of approximately 70 % of the Company’s workforce, or the Restructuring. In connection with the Restructuring, the Company incurred costs of $ 2.9 million, consisting primarily of cash severance costs and termination benefits, which the Company recognized during the year ended December 31, 2024. The Company substantially completed the Restructuring by December 31, 2024.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012, or JOBS Act. Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it is (1) no longer an emerging growth company and (2) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act, unless early adoption is permitted. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In November 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2023-07, Segment Reporting (Topic 280), Improvements to Reportable Segment Disclosures to improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses on an interim and annual basis. All disclosure requirements of ASU 2023-07 are required for entities with a single reportable segment. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods for the fiscal years beginning after December 15, 2024, and should be applied on a retrospective basis to all periods presented. Early adoption is permitted. The Company adopted the guidance in the fiscal year beginning January 1, 2024 , including the additional required disclosures in Note 6. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740) - Improvements to Income Tax Disclosures. The ASU requires that an entity disclose specific categories in the effective tax rate reconciliation as well as provide additional information for reconciling items that meet a quantitative threshold. Further, the ASU requires certain disclosures of state versus federal income tax expense and taxes paid. The amendments in this ASU are required to be adopted for fiscal years beginning after December 15, 2024. Early adoption is permitted and the amendments should be applied on a prospective basis. The Company does not expect the adoption of this new guidance to have a material impact on its consolidated financial statements and is currently evaluating the effect of adopting the ASU on its disclosures .

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
Significant Accounting Policies (Tables)	Dec. 31, 2024
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	The table below reconciles the balances of cash and cash equivalents and restricted cash reported on the consolidated balance sheets to the balances of cash, cash equivalents and restricted cash reported on the consolidated statements of cash flows. December 31, 2024 2023 Cash and cash equivalents $ 48,438 $ 90,584 Restricted cash 631 631 Cash, cash equivalents and restricted cash $ 49,069 $ 91,215

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
Fair Value (Tables)	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Cash Equivalents and Short-term Investments	The following tables reflect the Company’s financial asset balances measured at fair value on a recurring basis (in thousands): December 31, 2024 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 30 $ — $ — $ 30 U.S. government debt and agency 2 $ 10,297 $ 2 $ — $ 10,299 Commercial paper 2 19,394 — ( 1 ) 19,393 Total cash equivalents $ 29,721 $ 2 $ ( 1 ) $ 29,722 Short-term investments: Commercial paper 2 1,445 — — 1,445 U.S. government debt and agency 2 1,392 — — 1,392 Total short-term investments $ 2,837 $ — $ — $ 2,837 December 31, 2023 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 63 $ — $ — $ 63 Commercial paper 2 59,227 — ( 30 ) 59,197 Total cash equivalents $ 59,290 $ — $ ( 30 ) $ 59,260 Short-term investments: Commercial paper 2 6,431 — ( 4 ) 6,427 U.S. government debt and agency 2 50,723 — ( 315 ) 50,408 Total short-term investments $ 57,154 $ — $ ( 319 ) $ 56,835

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
Property and Equipment, Net (Tables)	Dec. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): December 31, 2024 2023 Lab equipment $ 705 $ 688 Office furniture, fixtures, and 712 712 Leasehold improvement 4,322 4,322 Property and equipment, at cost 5,739 5,722 Less: accumulated depreciation ( 3,295 ) ( 2,334 ) Property and equipment, net $ 2,444 $ 3,388

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
Accrued Liabilities (Tables)	Dec. 31, 2024
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): December 31, 2024 2023 Research and development $ 3,424 $ 11,916 Employee compensation and benefits 2,990 4,545 Legal expense 4,127 — Professional services and other 1,861 1,882 Total accrued liabilities $ 12,402 $ 18,343

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
Segment Reporting (Tables)	Dec. 31, 2024
Segment Reporting [Abstract]
Schedule of Segment Profit or Loss	The table below is a summary of the segment profit or loss, including significant segment expenses (in thousands): Year Ended December 31, 2024 2023 Research and development expenses: Fosgonimeton (ATH-1017) $ 41,510 $ 66,524 ATH-1105 8,567 $ — ATH-1020 495 704 Preclinical programs and other costs 3,390 8,219 Personnel-related costs, excluding stock- 12,289 13,952 Total research and development expenses 66,251 89,399 General and administrative expenses 22,631 24,475 Other segment expenses (a) 12,020 11,592 Total operating expenses 100,902 125,466 Loss from operations ( 100,902 ) ( 125,466 ) Grant income — 157 Other income, net 3,962 7,637 Net loss $ ( 96,940 ) $ ( 117,672 ) (a) Other segment expenses includes stock-based compensation and depreciation expenses.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Reconciliation of Undiscounted Operating Lease Cash Flows to Operating Lease Liability Payments	The following table reconciles the Company’s undiscounted operating lease cash flows to its operating lease liability (in thousands): December 31, 2025 494 2026 509 Thereafter 346 Total undiscounted lease payments 1,349 Present value adjustment for minimum lease ( 132 ) Net lease liability $ 1,217
Weighted Average Remaining Lease Term and Weighted Average Discount Rate to Determine the Operating Lease Liability	The weighted average remaining lease term and the weighted average discount rate used to determine the operating lease liability were as follows: December 31, Weighted average remaining lease term (years) 2.7 Weighted average discount rate 8.1 %

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
Common Stock (Tables)	Dec. 31, 2024
Equity [Abstract]
Schedule of Reserved Shares of Common Stock for Future Issuance	The Company has reserved the following shares of common stock for future issuance, on an as-converted basis, as follows: December 31, 2024 2023 Shares issuable upon the exercise of outstanding 10,234,971 7,130,956 Shares available for future grant under the 2020 1,666,381 3,158,094 Shares available for future grant under the 1,338,444 1,128,732 Shares available for future grant under the 2024 350,000 — Total 13,589,796 11,417,782

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
Stock-based Compensation (Tables)	Dec. 31, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based Compensation Expense Recognized	Stock‑based compensation expense recognized was as follows (in thousands): Year Ended December 31, 2024 2023 Research and development $ 4,043 $ 4,003 General and administrative 7,006 6,620 Total stock-based compensation expense $ 11,049 $ 10,623
Weighted-Average Assumptions used in Estimating Fair Value of each Stock Options using Black-Scholes Option-Pricing Model	The fair value of each stock option was estimated using the Black‑Scholes option‑pricing model with the following weighted-average assumptions: Year Ended December 31, 2024 2023 Risk-free interest rate 4.13 % 3.54 % Expected volatility 97.21 % 99.18 % Expected term (in years) 5.88 5.84 Expected dividend yield — —
Summary of Option Activity Changes in Shares Available for Grant under the 2020 Plan and the 2024 Inducement Plan	Changes in shares available for grant under the 2020 Plan and the 2024 Inducement Plan during the year ended December 31, 2024 were as follows: Shares Shares available for grant at December 31, 2023 3,158,094 2020 Plan reserve increase on January 1, 2024 1,908,630 Shares reserved upon adoption of the 750,000 Options and restricted stock units granted ( 5,986,613 ) Options and restricted stock units forfeited, 2,186,270 Shares available for grant at December 31, 2024 2,016,381
Summary of Option Activity under the 2020 Plan and the 2024 Inducement Plan	A summary of stock option activity under the 2020 Plan and the 2024 Inducement Plan for the year ended December 31, 2024 was as follows: Shares Weighted- Weighted- Aggregate Balance at December 31, 2023 6,820,869 $ 7.97 8.24 $ 387 Granted 5,052,871 2.64 Exercised ( 75,660 ) 0.16 Forfeited/expired ( 2,185,770 ) 4.21 Balance at December 31, 2024 9,612,310 $ 6.08 8.08 $ 130 Expected to vest 4,055,037 $ 3.79 8.82 $ 87 Options exercisable 5,557,273 $ 7.75 7.53 $ 43
Summary of Stock Options Outstanding and Exercisable under the 2020 Plan and the 2024 Inducement Plan	Stock options outstanding and exercisable under the 2020 Plan and the 2024 Inducement Plan consisted of the following at December 31, 2024: Exercise Price ($) Options Options 0.43 to 0.71 964,067 310,581 1.04 to 4.22 5,771,807 2,834,921 8.93 to 19.94 2,528,788 2,136,223 20.55 to 29.41 347,648 275,548 Total 9,612,310 5,557,273
Restricted Stock Units (RSUs)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Restricted Stock Activity	A summary of restricted stock unit, or RSU, activity for the year ended December 31, 2024 is as follows: Share Weighted- Non-vested at December 31, 2023 310,087 $ 11.44 Granted 933,742 0.46 Cancelled ( 500 ) 2.51 Vested ( 620,668 ) 5.94 Non-vested at December 31, 2024 622,661 $ 0.46

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Components of Income (Loss) Before Income Tax	The Company did not record a provision (benefit) for income taxes for the years ended December 31, 2024 and 2023. Net loss is attributable to the following tax jurisdictions (in thousands): Year Ended December 31, 2024 2023 United States $ ( 96,910 ) $ ( 117,440 ) Foreign ( 30 ) ( 232 ) Net Loss $ ( 96,940 ) $ ( 117,672 )
Schedule of Effective Income Tax Rate Reconciliation	The provision for income taxes differs from the amount expected by applying the federal statutory rates to the net loss before taxes as follows: Year Ended December 31, 2024 2023 Federal statutory income tax rate 21.0 % 21.0 % State taxes — — Stock-based compensation ( 1.8 ) ( 1.1 ) Non-deductible expenses and others ( 0.9 ) ( 0.1 ) Tax credits 3.1 4.2 Change in valuation allowance ( 21.4 ) ( 24.0 ) Effective income tax rate — % — %
Components of Deferred Tax Assets and Liabilities	The components of the Company’s deferred tax assets and liabilities were as follows (in thousands): Year Ended December 31, 2024 2023 Deferred tax assets: Net operating loss carryforwards $ 43,414 $ 31,342 Research and development tax credit 12,362 9,327 Accrued liabilities 538 2,828 Stock-based compensation 2,867 2,564 Operating lease liability 256 333 Other 258 180 Capitalized research and development 32,540 25,182 Total deferred tax assets 92,235 71,756 Deferred tax liabilities: Right of use asset ( 170 ) ( 221 ) Prepaid expenses and other ( 82 ) ( 75 ) Investments ( 34 ) ( 214 ) Total deferred tax liabilities ( 286 ) ( 510 ) Less valuation allowance ( 91,949 ) ( 71,246 ) Net deferred tax assets $ — $ —
Schedule of Unrecognized Tax Benefits for Uncertain Tax Positions	A reconciliation of the beginning and ending amount of unrecognized tax benefits for uncertain tax positions were as follows (in thousands): Year Ended December 31, 2024 2023 Beginning balance $ 3,109 $ 1,406 Additions for tax positions taken in prior — 182 Additions for tax positions taken in the current 1,012 1,521 Ending balance $ 4,121 $ 3,109

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2024
Earnings Per Share [Abstract]
Summary of Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders	The following outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share attributable to common stockholders for the periods presented because their effect would have been anti-dilutive: Year Ended December 31, 2024 2023 Stock options to purchase common stock 9,612,310 6,820,869 Non-vested Restricted Stock Units 622,661 310,087 Employee stock purchase plan 8,507 3,495 Total 10,243,478 7,134,451

Corporate Restructuring (Tables

Corporate Restructuring (Tables)	12 Months Ended
Corporate Restructuring (Tables)	Dec. 31, 2024
Restructuring and Related Activities [Abstract]
Summary of Cost Associated With Termination Benefit Payment of Restructuring	The Company expensed the following costs associated with the termination benefit payments resulting from the Restructuring (in thousands): Year Ended December 31, 2024 Research and development expense 1,495 General and administrative expense 1,392 Total severance expense 2,887

Description of Business - Addit

Description of Business - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Description Of Business [Line Items]
Entity incorporation, date of Incorporation		Mar. 31, 2011
Entity reincorporation, date of reincorporation		Oct. 27, 2015
Net cash proceeds from issuance of convertible preferred stock, common stock warrants, and convertible notes		$ 407,400
Cash, cash equivalents, and investments		51,300
Net loss		(96,940)	$ (117,672)
Cash used in operations		$ (97,200)
At The Market Common Stock Offering
Description Of Business [Line Items]
Number of shares issued and sold	0
At The Market Common Stock Offering \| Maximum
Description Of Business [Line Items]
Aggregate Offering Price	$ 75,000

Significant Accounting Polici_4

Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Cash and cash equivalents	$ 48,438	$ 90,584
Restricted cash	631	631
Cash, cash equivalents and restricted cash	$ 49,069	$ 91,215	$ 96,386

Significant Accounting Polici_5

Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Sep. 15, 2024	Dec. 31, 2024 USD ($) Segment	Dec. 31, 2023 USD ($)
Basis Of Presentation And Significant Accounting Policies [Line Items]
Impairment losses		$ 0	$ 0
Grant income			157,000
Number of operating segments \| Segment		1
Percentage of termination in workforce	70%
Restructuring and related cost, incurred cost		$ 2,900,000
ASU 2023-07
Basis Of Presentation And Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2024
ASU 2023-09
Basis Of Presentation And Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted		true
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
National Institutes of Health Grant
Basis Of Presentation And Significant Accounting Policies [Line Items]
Grants received		$ 0	1,400,000
Grant income		0	$ 200,000
Aggregate grant income		15,200,000
Additional grant income		$ 0
Minimum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Property and equipment useful life		3 years
Maximum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Property and equipment useful life		5 years

Fair Value - Schedule of Fair V

Fair Value - Schedule of Fair Value of Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	$ 48,438	$ 90,584
Recurring Basis \| Short-term Investments
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	2,837	57,154
Investments, Unrealized Losses		(319)
Investments, Fair Value	2,837	56,835
Recurring Basis \| Short-term Investments \| Commercial Paper \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	1,445	6,431
Investments, Unrealized Losses		(4)
Investments, Fair Value	1,445	6,427
Recurring Basis \| Short-term Investments \| U.S. Government Debt and Agency Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	1,392	50,723
Investments, Unrealized Losses		(315)
Investments, Fair Value	1,392	50,408
Recurring Basis \| Cash Equivalents
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	29,721	59,290
Cash equivalents, Unrealized Gains	2
Cash equivalents, Unrealized Losses	(1)	(30)
Cash equivalents, Fair Value	29,722	59,260
Recurring Basis \| Cash Equivalents \| Money Market Fund \| Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	30	63
Cash equivalents, Fair Value	30	63
Recurring Basis \| Cash Equivalents \| Commercial Paper \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	19,394	59,227
Cash equivalents, Unrealized Losses	(1)	(30)
Cash equivalents, Fair Value	19,393	$ 59,197
Recurring Basis \| Cash Equivalents \| U.S. Government Debt and Agency Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	10,297
Cash equivalents, Unrealized Gains	2
Cash equivalents, Fair Value	$ 10,299

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 5,739	$ 5,722
Less: accumulated depreciation	(3,295)	(2,334)
Property and equipment, net	2,444	3,388
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	705	688
Office Furniture, Fixtures, and Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	712	712
Leasehold Improvement
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 4,322	$ 4,322

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 970,000	$ 969,000

Accrued Liabilities - Schedule

Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Research and development	$ 3,424	$ 11,916
Employee compensation and benefits	2,990	4,545
Legal expense	4,127
Professional services and other	1,861	1,882
Total accrued Liabilities	$ 12,402	$ 18,343

Segment Reporting - Additional

Segment Reporting - Additional Information (Details)	12 Months Ended
Segment Reporting - Additional Information (Details)	Dec. 31, 2024 Segment
Segment Reporting [Abstract]
Number of operating segments	1
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The Company’s chief operating decision maker, or CODM, its chief executive officer, reviews financial information on an aggregate basis for the purpose of allocating resources and assessing performance. When deciding how to allocate resources, the CODM reviews the financial results of the Company's drug candidate programs. The measure of segment assets is reported on the consolidated balance sheet as total assets.
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	srt:ChiefExecutiveOfficerMember

Segment Reporting - Schedule of

Segment Reporting - Schedule of Segment Profit or Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Research and development expenses	$ 66,251	$ 89,399
General and administrative expenses	22,631	24,475
Other segment expenses	12,020	11,592
Total operating expenses	100,902	125,466
Loss from operations	(100,902)	(125,466)
Grant income		157
Other income, net	3,962	7,637
Net loss	(96,940)	(117,672)
Fosgonimeton (ATH-1017)
Segment Reporting Information [Line Items]
Research and development expenses	41,510	66,524
ATH-1105
Segment Reporting Information [Line Items]
Research and development expenses	8,567
ATH-1020
Segment Reporting Information [Line Items]
Research and development expenses	495	704
Preclinical Programs and Other Costs
Segment Reporting Information [Line Items]
Research and development expenses	3,390	8,219
Personnel-Related Costs, Excluding Stock- Based Compensation
Segment Reporting Information [Line Items]
Research and development expenses	$ 12,289	$ 13,952

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)			3 Months Ended			12 Months Ended
	Dec. 31, 2024	Mar. 29, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2024	Dec. 31, 2023	Jan. 31, 2025
Commitments And Contingencies [Line Items]
Settlement on litigation	$ 4,100,000	$ 10,000,000
Legal settlement expense			$ 4,100,000		$ 10,000,000	$ 4,127,000
Accrued legal liability	$ 4,100,000		$ 4,100,000			4,100,000
Insurance recovery in operating expenses				$ 1,600,000			$ 1,628,000
Insurance recovery receivable				1,628,000			1,628,000
Accrued legal settlement				$ 10,000,000	$ 10,000,000		10,000,000
Operating lease expense						353,000	353,000
Variable lease expense						$ 149,000	$ 186,000
Subsequent Event
Commitments And Contingencies [Line Items]
Accrued legal settlement								$ 4,100,000
Laboratory and Office Facilities \| Bothell, Washington
Commitments And Contingencies [Line Items]
Operating lease expiration month and year						2027-08
Operating lease existence of option to extend						true
Operating lease, additional term of contract	5 years		5 years			5 years
Laboratory and Office Facilities \| Bothell, Washington \| Minimum
Commitments And Contingencies [Line Items]
Operating lease initial term	6 years 3 months 18 days		6 years 3 months 18 days			6 years 3 months 18 days
Laboratory and Office Facilities \| Bothell, Washington \| Maximum
Commitments And Contingencies [Line Items]
Operating lease initial term	7 years		7 years			7 years

Commitments and Contingencies_2

Commitments and Contingencies - Reconciliation of Undiscounted Operating Lease Cash Flows to Operating Lease Liability Payments (Details) $ in Thousands	Dec. 31, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2025	$ 494
2026	509
Thereafter	346
Total undiscounted lease payments	1,349
Present value adjustment for minimum lease commitments	(132)
Net lease liability	$ 1,217

Commitments and Contingencies_3

Commitments and Contingencies - Weighted Average Remaining Lease Term and Weighted Average Discount Rate to Determine the Operating Lease Liability (Details)	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Weighted average remaining lease term (years)	2 years 8 months 12 days
Weighted average discount rate	8.10%

Common Stock - Schedule of Rese

Common Stock - Schedule of Reserved Shares of Common Stock for Future Issuance (Details) - shares	Dec. 31, 2024	Dec. 31, 2023
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	13,589,796	11,417,782
Shares Issuable Upon the Exercise of Outstanding Common Stock Options and the Vesting of Outstanding Common Restricted Stock Units Granted
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	10,234,971	7,130,956
Shares Available for Future Grant under 2020 Equity Incentive Plan
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	1,666,381	3,158,094
Shares Available for Future Grant under Employee Stock Purchase Plan
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	1,338,444	1,128,732
Shares Available for Future Grant under 2024 Inducement Equity Incentive Plan
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	350,000

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - shares	12 Months Ended
Common Stock - Additional Information (Details) - shares	Dec. 31, 2024	Jan. 01, 2025	Feb. 29, 2024	Jan. 01, 2024	Dec. 31, 2023
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	13,589,796				11,417,782
2020 Equity Incentive Plan
Class Of Stock [Line Items]
Share based compensation maximum annual increase in number of shares that may be issued under the plan	3,230,000
Share based compensation percentage of number shares of common stock issued and outstanding on immediate proceeding	5%
Reserved shares of common stock for future issuance				1,908,630
2020 Equity Incentive Plan \| Subsequent Event
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance		1,952,047
2020 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Share based compensation maximum annual increase in number of shares that may be issued under the plan	646,000
Share based compensation percentage of number shares of common stock issued and outstanding on immediate proceeding	1%
Reserved shares of common stock for future issuance				381,726
2020 Employee Stock Purchase Plan \| Subsequent Event
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance		390,409
2024 Inducement Equity Incentive Plan
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance			750,000

Stock-based Compensation - Stoc

Stock-based Compensation - Stock-based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 11,049	$ 10,623
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,043	4,003
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7,006	$ 6,620

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield		0%
Fair value of options granted		$ 10,600	$ 9,800
Fair value of restricted stock units granted		400	500
Fair value of options vested		11,000	9,800
Aggregate intrinsic value of options exercised		200	200
Unrecognized compensation cost		$ 9,800
Remaining weighted-average period expected to recognize unrecognized compensation cost		1 year 11 months 26 days
Stock-based compensation expense		$ 11,049	10,623
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issued common stock, share under employee stock purchase plan		172,014
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Terms of award		Under the ESPP, eligible employees can authorize payroll deductions for amounts up to the lesser of 15% of their qualifying wages or the statutory limit under the U.S. Internal Revenue Code. The ESPP provides for offering periods of six months in duration with one purchase period per offering period beginning May 18 and November 18 of each year.
Offering periods	6 months
Percentage of fair market value of common shares	85%
Stock-based compensation expense		$ 100	$ 100
Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum percentage of payroll deductions for qualifying wages or statutory limit	15%
Shares of common stock purchased by each participant		10,000
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost		$ 200
Remaining weighted-average period expected to recognize unrecognized compensation cost		9 months 7 days

Stock-based Compensation - Weig

Stock-based Compensation - Weighted-Average Assumptions used in Estimating Fair Value of each Stock Options using Black-Scholes Option-Pricing Model (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Risk-free interest rate	4.13%	3.54%
Expected volatility	97.21%	99.18%
Expected term (in years)	5 years 10 months 17 days	5 years 10 months 2 days
Expected dividend yield	0%

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Option Activity Changes in Shares Available for Grant under the 2020 Plan and the 2024 Inducement Plan (Details)	12 Months Ended
	Dec. 31, 2024 shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares Available for Grant, Beginning Balance	3,158,094
Options and restricted stock units granted	(5,986,613)
Options and restricted stock units forfeited, cancelled, or expired	2,186,270
Shares Available for Grant, Ending Balance	2,016,381
2020 Equity Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares reserved	1,908,630
2024 Inducement Equity Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares reserved	750,000

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Option Activity under the 2020 Plan and the 2024 Inducement Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Shares, Beginning Balance	6,820,869
Shares, Granted	5,052,871
Shares, Exercised	(75,660)
Shares, Forfeited/expired	(2,185,770)
Shares, Ending Balance	9,612,310	6,820,869
Shares, Expected to vest	4,055,037
Shares, Options exercisable	5,557,273
Weighted-Average Exercise price per Share, Beginning Balance	$ 7.97
Weighted-Average Exercise price per Share, Granted	2.64
Weighted-Average Exercise price per Share, Exercised	0.16
Weighted-Average Exercise price per Share, Forfeited/expired	4.21
Weighted-Average Exercise price per Share, Ending Balance	6.08	$ 7.97
Weighted-Average Exercise price per Share, Expected to vest	3.79
Weighted-Average Exercise price per Share, Options exercisable	$ 7.75
Weighted-Average Remaining Contractual Term (in years)	8 years 29 days	8 years 2 months 26 days
Weighted-Average Remaining Contractual Term, Expected to vest (in years)	8 years 9 months 25 days
Weighted-Average Remaining Contractual Term, Options exercisable (in years)	7 years 6 months 10 days
Aggregate Intrinsic Value, Outstanding Balance	$ 130	$ 387
Aggregate Intrinsic Value, Expected to vest	87
Aggregate Intrinsic Value, Options exercisable	$ 43

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Stock Options Outstanding and Exercisable under the 2020 Plan and the 2024 Inducement Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding	9,612,310	6,820,869
Options Exercisable	5,557,273
Exercise Price $0.43 to 0.71
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding	964,067
Options Exercisable	310,581
Exercise Price $0.43 to 0.71 \| Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 0.43
Exercise Price $0.43 to 0.71 \| Maximum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 0.71
Exercise Price $1.04 to 4.22
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding	5,771,807
Options Exercisable	2,834,921
Exercise Price $1.04 to 4.22 \| Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 1.04
Exercise Price $1.04 to 4.22 \| Maximum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 4.22
Exercise Price $8.93 to 19.94
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding	2,528,788
Options Exercisable	2,136,223
Exercise Price $8.93 to 19.94 \| Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 8.93
Exercise Price $8.93 to 19.94 \| Maximum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 19.94
Exercise Price $20.55 to 29.41
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding	347,648
Options Exercisable	275,548
Exercise Price $20.55 to 29.41 \| Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 20.55
Exercise Price $20.55 to 29.41 \| Maximum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 29.41

Stock-based Compensation - Su_4

Stock-based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2024 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share Equivalent, Non-vested, Beginning Balance \| shares	310,087
Share Equivalent, Granted \| shares	933,742
Share Equivalent, Cancelled \| shares	(500)
Share Equivalent, Vested \| shares	(620,668)
Share Equivalent, Non-vested, Ending Balance \| shares	622,661
Weighted-Average Grant Date Fair Value, Non-vested, Beginning Balance \| $ / shares	$ 11.44
Weighted-Average Grant Date Fair Value, Non-vested, Granted \| $ / shares	0.46
Weighted-Average Grant Date Fair Value, Non-vested, Cancelled \| $ / shares	2.51
Weighted-Average Grant Date Fair Value, Non-vested, Vested \| $ / shares	5.94
Weighted-Average Grant Date Fair Value, Non-vested, Ending Balance \| $ / shares	$ 0.46

Income Taxes - Components of In

Income Taxes - Components of Income (Loss) Before Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
United States	$ (96,910)	$ (117,440)
Foreign	(30)	(232)
Net loss	$ (96,940)	$ (117,672)

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21%	21%
Stock-based compensation	(1.80%)	(1.10%)
Non-deductible expenses and others	(0.90%)	(0.10%)
Tax credits	3.10%	4.20%
Change in valuation allowance	(21.40%)	(24.00%)
Effective income tax rate	0%	0%

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Net operating loss carryforwards	$ 43,414	$ 31,342
Research and development tax credit carryforwards	12,362	9,327
Accrued liabilities	538	2,828
Stock-based compensation	2,867	2,564
Operating lease liability	256	333
Other	258	180
Capitalized research and development	32,540	25,182
Total deferred tax assets	92,235	71,756
Deferred tax liabilities:
Right of use asset	(170)	(221)
Prepaid expenses and other	(82)	(75)
Investments	(34)	(214)
Total deferred tax liabilities	(286)	(510)
Less valuation allowance	(91,949)	(71,246)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
Income Taxes - Additional Information (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Income Tax Contingency [Line Items]
Change in valuation allowance	$ 20,700,000	$ 28,300,000
Net operating loss carryforwards	196,000,000
Material interest and penalties on uncertain tax benefits	0
Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards	9,500,000
Tax credit carryforwards	16,500,000
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 3,900,000
Minimum \| Federal
Income Tax Contingency [Line Items]
Net operating loss and tax credit carryforwards, expiration period	7 years
Minimum \| State
Income Tax Contingency [Line Items]
Operating loss carryforwards, expiration period	17 years
Maximum \| Federal
Income Tax Contingency [Line Items]
Net operating loss and tax credit carryforwards, expiration period	13 years
Maximum \| State
Income Tax Contingency [Line Items]
Operating loss carryforwards, expiration period	20 years

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits for Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Beginning balance	$ 3,109	$ 1,406
Additions for tax positions taken in prior year		182
Additions for tax positions taken in the current year	1,012	1,521
Ending balance	$ 4,121	$ 3,109

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Employee Benefit Plans [Abstract]
Percentage of pretax compensation eligible to defer	100%
Matching contributions	$ 0.5	$ 0.5

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Summary of Dilutive Securities excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share	10,243,478	7,134,451
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share	9,612,310	6,820,869
Non-vested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share	622,661	310,087
Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share	8,507	3,495

Corporate Restructuring - Addit

Corporate Restructuring - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, estimated to incur	$ 2.9
Accrued liability associated with restructuring	0.4
Termination Benefits
Restructuring Cost and Reserve [Line Items]
Cash paid	$ 2.5

Corporate Restructuring - Summa

Corporate Restructuring - Summary of Cost Associated With Termination Benefit Payment of Restructuring (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Total severance expense	$ 2,887
Research and Development
Restructuring Cost and Reserve [Line Items]
Total severance expense	1,495
General and Administrative
Restructuring Cost and Reserve [Line Items]
Total severance expense	$ 1,392