Athira Pharma (ATHA) 10-Q 10 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 05, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Registrant Name	Athira Pharma, Inc.
Entity Central Index Key	0001620463
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		37,351,104
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity File Number	001-39503
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-3368487
Entity Address, Address Line One	18706 North Creek Parkway,
Entity Address, Address Line Two	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 Quarterly Report	true
Document Transition Report	false
Security12b Title	Common Stock, $0.0001 par value per share
Trading Symbol	ATHA
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 107,328	$ 60,625
Short-term investments	128,447	124,057
Unbilled grant receivable	2,079	1,300
Prepaid expenses and other current assets	1,138	6,355
Total current assets	238,992	192,337
Property and equipment, net	3,061	2,649
Operating lease right-of-use asset	1,504	936
Long-term investments	103,649	83,509
Other long-term assets	125	132
Total assets	347,331	279,563
Current liabilities:
Accounts payable	959	1,158
Accrued liabilities	8,148	3,123
Current operating lease liability	279	124
Total current liabilities	9,386	4,405
Operating lease liability, less current portion	1,708	876
Total liabilities	11,094	5,281
Stockholders' equity:
Common stock, $0.00012 par value; 900,000,0002 shares authorized at September 30, 2021 and December 31, 2020, respectively; 37,351,1042 and 32,485,7842 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	4	3
Additional paid-in capital	415,785	315,288
Accumulated other comprehensive income	4	33
Accumulated deficit	(79,556)	(41,042)
Total stockholders' equity	336,237	274,282
Total liabilities and stockholders' equity	$ 347,331	$ 279,563

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
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	37,351,104	32,485,784
Common stock, shares outstanding	37,351,104	32,485,784

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating expenses:
Research and development	$ 10,707	$ 5,830	$ 30,176	$ 8,099
General and administrative	7,119	1,567	15,068	2,817
Total operating expenses	17,826	7,397	45,244	10,916
Loss from operations	(17,826)	(7,397)	(45,244)	(10,916)
Grant income	2,079		6,499	22
Other income (expense), net	73	(1,059)	231	(1,359)
Net loss	(15,674)	(8,456)	(38,514)	(12,253)
Unrealized (loss) gain on available-for-sale securities	(33)	7	(29)	7
Comprehensive loss attributable to common stockholders	$ (15,707)	$ (8,449)	$ (38,543)	$ (12,246)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.42)	$ (1.12)	$ (1.12)	$ (2.38)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	37,312,356	7,564,538	34,315,047	5,155,338

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders (Deficit) Equity (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ (19,723)			$ 1,364		$ (21,087)
Temporary equity, beginning balance, shares at Dec. 31, 2019		2,617,386
Temporary equity, beginning balance at Dec. 31, 2019		$ 17,051
Beginning balance, shares at Dec. 31, 2019			3,641,449
Issuance of common stock upon exercise of common stock options	176			176
Issuance of common stock upon exercise of common stock options, shares			220,043
Stock-based compensation	58			58
Net loss	(1,805)					(1,805)
Ending balance at Mar. 31, 2020	(21,294)			1,598		(22,892)
Temporary equity, ending balance, shares at Mar. 31, 2020		2,617,386
Temporary equity, ending balance at Mar. 31, 2020		$ 17,051
Ending balance, shares at Mar. 31, 2020			3,861,492
Beginning balance at Dec. 31, 2019	(19,723)			1,364		(21,087)
Temporary equity, beginning balance, shares at Dec. 31, 2019		2,617,386
Temporary equity, beginning balance at Dec. 31, 2019		$ 17,051
Beginning balance, shares at Dec. 31, 2019			3,641,449
Net loss	(12,253)
Ending balance at Sep. 30, 2020	259,470		$ 3	292,800	$ 7	(33,340)
Ending balance, shares at Sep. 30, 2020			31,087,395
Beginning balance at Mar. 31, 2020	(21,294)			1,598		(22,892)
Temporary equity, beginning balance, shares at Mar. 31, 2020		2,617,386
Temporary equity, beginning balance at Mar. 31, 2020		$ 17,051
Beginning balance, shares at Mar. 31, 2020			3,861,492
Issuance of common stock upon exercise of common stock options	62			62
Issuance of common stock upon exercise of common stock options, shares			58,006
Issuance of Series B convertible preferred stock and common stock warrants, net of issuance costs of $3.5 million	10,591			10,591
Temporary Equity, Issuance of Series B convertible preferred stock and common stock warrants, net, shares		9,372,765
Temporary Equity, Issuance of Series B convertible preferred stock and common stock warrants, net		$ 70,971
Temporary Equity, Issuance of the Series B-1 convertible preferred stock upon conversion of convertible notes, shares		512,858
Temporary Equity, Issuance of the Series B-1 convertible preferred stock upon conversion of convertible notes		$ 4,515
Exercise of common stock warrants	55			55
Exercise of common stock warrants, shares			688,067
Stock-based compensation	49			49
Net loss	(1,992)					(1,992)
Ending balance at Jun. 30, 2020	(12,529)			12,355		(24,884)
Temporary equity, ending balance, shares at Jun. 30, 2020		12,503,009
Temporary equity, ending balance at Jun. 30, 2020		$ 92,537
Ending balance, shares at Jun. 30, 2020			4,607,565
Issuance of common stock upon exercise of common stock options	304			304
Issuance of common stock upon exercise of common stock options, shares			262,285
Proceeds from initial public offering, net of underwriters' discounts and commissions and issuance costs	186,446		$ 1	186,445
Proceeds from initial public offering, net of underwriters' discounts and commissions and issuance costs, Shares			12,000,000
Conversion of convertible preferred stock	92,537		$ 2	92,535
Temporary equity, conversion of convertible preferred stock, shares		(12,503,009)
Temporary equity, conversion of convertible preferred stock		$ (92,537)
Conversion of convertible preferred stock, shares			12,503,009
Exercise of common stock warrants	1,050			1,050
Exercise of common stock warrants, shares			1,714,536
Stock-based compensation	111			111
Other comprehensive income (loss)	7				7
Net loss	(8,456)					(8,456)
Ending balance at Sep. 30, 2020	259,470		$ 3	292,800	7	(33,340)
Ending balance, shares at Sep. 30, 2020			31,087,395
Beginning balance at Dec. 31, 2020	274,282		$ 3	315,288	33	(41,042)
Beginning balance, shares at Dec. 31, 2020			32,485,784
Proceeds from initial public offering, net of underwriters' discounts and commissions and issuance costs	96,762		$ 1	96,761
Proceeds from initial public offering, net of underwriters' discounts and commissions and issuance costs, Shares			4,600,000
Issuance of common stock upon exercise of common stock options and vesting of restricted stock units	70			70
Issuance of common stock upon exercise of common stock options and vesting of restricted stock units, Shares			64,527
Stock-based compensation	974			974
Other comprehensive income (loss)	(5)				(5)
Net loss	(8,866)					(8,866)
Ending balance at Mar. 31, 2021	363,217		$ 4	413,093	28	(49,908)
Ending balance, shares at Mar. 31, 2021			37,150,311
Beginning balance at Dec. 31, 2020	$ 274,282		$ 3	315,288	33	(41,042)
Beginning balance, shares at Dec. 31, 2020			32,485,784
Issuance of common stock upon exercise of common stock options, shares	246,301
Issuance of common stock under employee stock purchase plan, shares			15,867
Net loss	$ (38,514)
Ending balance at Sep. 30, 2021	336,237		$ 4	415,785	4	(79,556)
Ending balance, shares at Sep. 30, 2021			37,351,104
Beginning balance at Mar. 31, 2021	363,217		$ 4	413,093	28	(49,908)
Beginning balance, shares at Mar. 31, 2021			37,150,311
Issuance of common stock upon exercise of common stock options	119			119
Issuance of common stock upon exercise of common stock options, shares			85,593
Issuance of common stock under employee stock purchase plan	229			229
Issuance of common stock under employee stock purchase plan, shares			15,867
Stock-based compensation	1,109			1,109
Other comprehensive income (loss)	9				9
Net loss	(13,974)					(13,974)
Ending balance at Jun. 30, 2021	350,709		$ 4	414,550	37	(63,882)
Ending balance, shares at Jun. 30, 2021			37,251,771
Issuance of common stock upon exercise of common stock options and vesting of restricted stock units	130			130
Issuance of common stock upon exercise of common stock options and vesting of restricted stock units, Shares			99,333
Stock-based compensation	1,105			1,105
Other comprehensive income (loss)	(33)				(33)
Net loss	(15,674)					(15,674)
Ending balance at Sep. 30, 2021	$ 336,237		$ 4	$ 415,785	$ 4	$ (79,556)
Ending balance, shares at Sep. 30, 2021			37,351,104

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders (Deficit) Equity (Parenthetical) (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020
Statement Of Stockholders Equity [Abstract]
Issuance of Series B convertible preferred stock and common stock warrants, issuance costs		$ 3.5
Initial public offering, issuance cost	$ 3.3

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities
Net loss	$ (38,514,000)	$ (12,253,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	3,188,000	218,000
Depreciation expense	353,000	0
Other non-cash expense		1,403,000
Amortization of premiums and accretion of discounts on available-for-sale securities, net	347,000	86,000
Changes in operating assets and liabilities:
Unbilled grant receivable	(779,000)
Prepaid expenses and other current assets	5,152,000	(5,919,000)
Accounts payable and accrued liabilities	4,913,000	3,004,000
Operating lease liability	419,000	13,000
Net cash used in operating activities	(24,921,000)	(13,448,000)
Investing activities
Purchases of available-for-sale securities	(269,378,000)	(94,281,000)
Maturities of available-for-sale securities	226,420,000
Proceeds from sales of available-for-sale securities	18,052,000
Purchases of property and equipment	(546,000)	(65,000)
Principal payments received on stockholder note receivable		36,000
Net cash used in investing activities	(25,452,000)	(94,310,000)
Financing activities
Proceeds from exercise of common stock options	314,000	542,000
Proceeds from initial public offering, net of issuance costs		187,224,000
Proceeds from issuance of convertible preferred stock and common stock warrants, net of issuance costs		81,926,000
Proceeds from exercise of common stock warrants		71,000
Proceeds from follow-on public offering, net of issuance costs	96,762,000
Proceeds from issuance of convertible notes, including derivative, net of issuance costs		1,664,000
Net cash provided by financing activities	97,076,000	271,427,000
Net increase in cash and cash equivalents	46,703,000	163,669,000
Cash and cash equivalents, beginning of period	60,625,000	2,056,000
Cash and cash equivalents, end of period	107,328,000	165,725,000
Supplemental disclosures of cash flow information:
Purchases of property and equipment included in accounts payable and accrued liabilities	219,000	940,000
Deferred offering costs included in accounts payable and accrued liabilities		776,000
Allocation of proceeds to common stock warrants issued in Series B convertible preferred stock financing		10,591,000
Issuance of Series B-1 preferred stock upon conversion of promissory notes		4,515,000
Recognition of warrant liability in connection with Series B convertible preferred stock financing		364,000
Recognition of derivative liability upon issuance of convertible notes		774,000
Conversion of convertible preferred stock upon closing of initial public offering		92,537,000
Right-of-use asset obtained in exchange for new operating lease liability	$ 680,000	$ 975,000

Description of Business

Description of Business	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	1. Description of Business Organization Athira Pharma, Inc. (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 and Seattle, Washington. The Company is a late clinical-stage biopharmaceutical company focused on developing small molecules to restore neuronal health and stop neurodegeneration. Follow-on Public Offering In January 2021, the Company completed a follow-on public offering of its common stock. As part of the follow-on offering, the Company issued and sold 4,000,000 shares of its common stock at a public offering price of $ 22.50 per share. The Company received net proceeds of approximately $ 84.1 million from the follow-on offering, after deducting underwriting discounts and commissions and offering costs. In February 2021, the Company sold an additional 600,000 shares of common stock to the underwriters of the follow-on public offering upon full exercise of the underwriters’ option to purchase additional shares at the follow-on public offering price of $ 22.50 per share, less underwriting discounts and commissions and offering costs resulting in net proceeds to the Company of approximately $ 12.7 million. 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 September 30, 2021, it has raised aggregate net cash proceeds of $ 407.4 million primarily from the issuance of its common stock, convertible preferred stock, common stock warrants, and convertible notes. As of September 30, 2021, the Company had $ 339.4 million in cash, cash equivalents, and investments and had not generated positive cash flows from operations. 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 $ 339.4 million of cash, cash equivalents, and investments at September 30, 2021 will be sufficient to fund its operating expenses and capital expenditure requirements through at least the 12 months following the date of this Quarterly Report on Form 10-Q.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	2 . Significant Accounting Policies Basis of Presentation The unaudited condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”). During the third quarter of 2020, the Company incorporated Athira Pharma Australia PTY LTD in Australia and since its creation, the Australian subsidiary’s financial position and results of operations are consolidated in the accompanying unaudited condensed consolidated financial statements. Unaudited Interim Condensed Consolidated Financial Statements The accompanying unaudited condensed consolidated balance sheet as of September 30, 2021, and condensed consolidated statements of operations and comprehensive loss, cash flows, and convertible preferred stock and stockholders’ (deficit) equity for the three and nine months ended September 30, 2021 and 2020, are unaudited. The balance sheet as of December 31, 2020 was derived from the audited consolidated financial statements as of and for the year ended December 31, 2020. The unaudited interim condensed consolidated financial statements have been prepared on a basis consistent with the audited annual financial statements as of and for the year ended December 31, 2020, and, in the opinion of management, reflect all adjustments, consisting solely of normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2021, and the condensed consolidated results of its operations and its cash flows for the three and nine months ended September 30, 2021 and 2020. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2021 and 2020 are also unaudited. The condensed consolidated results of operations for the three and nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the full year ending December 31, 2021 or any other period. These interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements as of and for the year ended December 31, 2020 included in its Annual Report on Form 10-K filed with the SEC on March 25, 2021. Fair Value Measurements The carrying amounts of certain financial instruments, including cash, cash equivalents, investments, accounts payable and accrued expenses approximate their fair values due to the short-term nature of those amounts. The fair values of the grant liability to Washington Life Sciences Discovery Fund (“LSDF”), currently managed by the Washington State Department of Commerce, the derivative liability, and the convertible preferred stock warrant liability were estimated using level 3 unobservable inputs. Convertible Preferred Stock Warrant Liability Freestanding warrants to purchase shares of the Company’s convertible preferred stock were accounted for as liabilities at fair value, because the shares underlying the warrants contained contingent redemption features outside the control of the Company. Warrants classified as liabilities are recorded on the Company’s balance sheets at their fair value on the date of issuance and remeasured to fair value on each subsequent reporting period, with the changes in fair value recognized as a component of other income (expense), net in the accompanying statements of operations. The Company adjusted the liability for the final change in the fair value of these warrants immediately preceding their automatic exercise in connection with the Company’s initial public offering (“IPO”). Subsequent to the Company’s IPO, the corresponding liability was reclassified to additional paid in capital. Grant Income Grant income in the accompanying statements of operations consisted of the following for the three and nine months ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Alzheimer's Association Part the Cloud $ — $ — $ — $ 22 National Institutes of Health Grant 2,079 — 6,499 — Total grant income $ 2,079 $ — $ 6,499 $ 22 Amounts recorded in the accompanying balance sheets as receivables from these granting agencies were as follows (in thousands): September 30, December 31, Alzheimer's Association Part the Cloud Research $ — $ 224 National Institutes of Health Grant 2,079 1,076 Total grant income $ 2,079 $ 1,300 In January 2019, the Alzheimer’s Association awarded the Company a $ 1.0 million Part the Cloud research grant. Grant proceeds must be used to advance the Company’s ATH-1017 product candidate in the Alzheimer’s disease setting. Reporting of expenses incurred supported by the grant as well as research updates are sent to the Alzheimer’s Association semi-annually. Under the terms of the agreement, the Company received $ 776,000 in 2019 and received the remaining $ 224,000 in March 2021 after having completed certain development milestones in October 2020. The Company recognized income related to the Part the Cloud research grant as qualifying expenses under the grant agreement were incurred. In December 2020, the Company accepted a grant from the National Institute on Aging (“NIA”) of the National Institutes of Health (“NIH”) to support its ACT-AD Phase 2 clinical trial for ATH-1017, the Company’s lead therapeutic candidate being developed for the treatment of individuals with mild-to-moderate Alzheimer’s disease. Under the terms of the agreement, the Company may potentially receive $ 7.8 million with the potential for an additional $ 7.4 million, up to an aggregate of $ 15.2 million. The Company recognizes income related to the NIH grant as qualifying expenses under the grant agreement are incurred. The Company received cash of $ 2.6 million and $ 5.5 million related to the NIH grant during the three and nine months ended September 30, 2021 , respectively. Short-term and Long-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, short-term investments, and long-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 or loss. Realized gains and losses on the sale of these securities are recognized in net loss. The Company periodically evaluates whether declines in fair values of its investments below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the investment until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any investment before recovery of its amortized cost basis. Factors considered include quoted market prices, recent financial results and operating trends, implied values from any recent transactions or offers of investee securities, credit quality of debt instrument issuers, other publicly available information that may affect the value of the investments, duration and severity of the decline in value, and our strategy and intentions for holding the investment. 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. 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 proprietary drug discovery platform (“ATH platform”). The Company’s drug discovery efforts and the development of its product 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. Leases The Company adopted Accounting Standards Codification (“ASC”) Topic 842 - Leases , on July 1, 2020, 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 (“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, discussed in more detail below. 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 lease includes 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 lease. 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. 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 grants subject to performance-based milestone vesting using the accelerated attribution method over the remaining 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. The Company adopted Accounting Standards Update (“ASU”) 2018-07 as of January 1, 2020 . As a result, stock-based payments issued to non-employees prior to January 1, 2020 have been recorded at their fair values as of the transition date and are no longer subject to periodic adjustments as the underlying equity instruments vest. Any remaining compensation expense is recognized over the remaining vesting term on a straight-line basis, which reflects the service period, based on the fair value as of January 1, 2020. 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. Segments The Company has determined that it operates and manages one operating segment, which is the business of developing and commercializing therapeutics. The Company’s chief operating decision maker, its chief executive officer, reviews financial information on an aggregate basis for the purpose of allocating resources. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (“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 (a) no longer an emerging growth company or (b) 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 Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments: Credit Losses (Topic 326) as clarified in ASU 2019-04, ASU 2019-05, and ASU 2020-02. The objective of the standard is to provide information about expected credit losses on financial instruments at each reporting date and to change how other-than-temporary impairments on investment securities are recorded. The ASU will become effective beginning January 1, 2023, with early adoption permitted. The Company is currently evaluating the potential impacts of the ASU on its financial condition, results of operations, cash flows and financial statement disclosures. Although there were several other new accounting pronouncements issued or proposed by the FASB, the Company does not believe any of these have had or will have material impact on its condensed consolidated financial statements.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2021
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 on a recurring basis as of September 30, 2021 and December 31, 2020 (in thousands): September 30, 2021 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 72,487 $ — $ — $ 72,487 Commercial paper 2 21,763 — ( 1 ) 21,762 Total cash equivalents $ 94,250 $ — $ ( 1 ) $ 94,249 Short-term investments: Commercial paper 2 85,642 5 ( 5 ) 85,642 U.S. government debt and agency 2 40,858 11 — 40,869 Corporate bonds 2 1,936 — — 1,936 Total short-term investments $ 128,436 $ 16 $ ( 5 ) $ 128,447 Long-term investments: Corporate bonds 2 3,308 — ( 4 ) 3,304 U.S. government debt and agency 2 100,347 17 ( 19 ) 100,345 Total long-term investments $ 103,655 $ 17 $ ( 23 ) $ 103,649 December 31, 2020 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 5 $ — $ — $ 5 Commercial paper 2 44,318 — ( 2 ) 44,316 U.S. government debt and agency 2 4,999 — — 4,999 U.S. treasury bills 2 4,450 — — 4,450 Total cash equivalents $ 53,772 $ — $ ( 2 ) $ 53,770 Short-term investments: Commercial paper 2 77,272 1 ( 4 ) 77,269 U.S. government debt and agency 2 31,835 7 — 31,842 U.S. treasury bills 2 14,029 — ( 3 ) 14,026 Corporate bonds 2 920 — — 920 Total short-term investments $ 124,056 $ 8 $ ( 7 ) $ 124,057 Long-term investments: U.S. government debt and agency 2 78,924 32 — 78,956 U.S. treasury bills 2 4,551 2 — 4,553 Total long-term investments $ 83,475 $ 34 $ — $ 83,509 All the commercial paper, U.S. government debt and agency securities, U.S. treasury bills, and corporate bonds 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. Those that are designated as long-term investments have an effective maturity date that is more than one year , but less than two years , from the respective balance sheet date. The Company evaluated its investments for other-than-temporary impairment and considers the decline in market value for the securities to be primarily attributable to current economic and market conditions. For the investments, it is not more-likely-than-not that the Company will be required to sell the investments, and the Company does not intend to do so prior to the recovery of the amortized cost basis.

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2021
Property Plant And Equipment [Abstract]
Property and Equipment, Net	. Property and Equipment, Net Property and equipment as of September 30, 2021 and December 31, 2020 consisted of the following (in thousands): September 30, December 31, Lab equipment $ 268 $ 81 Office furniture, fixtures, and 325 — Leasehold improvement 2,563 — Construction in progress 302 2,639 Property and equipment, at cost 3,458 2,720 Less: accumulated depreciation ( 397 ) ( 71 ) Property and equipment, net $ 3,061 $ 2,649 Depreciation expense was $ 123,000 and $ 353,000 for the three and nine months ended September 30, 2021 , respectively. The Company did no t incur depreciation expense during the three and nine months ended September 30, 2020 .

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Accrued Liabilities	5 . Accrued Liabilities Accrued liabilities consisted of the following (in thousands): September 30, December 31, Employee compensation and benefits $ 1,408 $ 1,624 Research and development expenses 5,332 1,169 Professional services and other 1,408 330 Total accrued liabilities $ 8,148 $ 3,123

Other Income (Expense), Net

Other Income (Expense), Net	9 Months Ended
	Sep. 30, 2021
Other Income And Expenses [Abstract]
Other Income (Expense), Net	6 . Other Income (Expense), Net Other income (expense), net consisted of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Interest and other income $ 74 $ 35 $ 232 $ 45 Interest expense ( 1 ) — ( 1 ) ( 366 ) Change in fair value of derivative liability — — — ( 132 ) Change in fair value of grant liability — ( 453 ) — ( 464 ) Change in convertible preferred stock — ( 641 ) ( 641 ) Gain on extinguishment of convertible notes — — — 199 Total other income (expense), net $ 73 $ ( 1,059 ) $ 231 $ ( 1,359 )

Significant Agreements

Significant Agreements	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Significant Agreements	7 . Significant Agreements Washington State University (“WSU”) License Agreement In December 2011, the Company entered into an exclusive license agreement with sublicensing terms with Washington State University Research Fund (“WSURF”), which, after the dissolution of WSURF in 2013, was superseded by an amended and restated exclusive license agreement with sublicensing terms between the Company and Washington State University (“WSU”) in 2015. Under this agreement, the Company has an exclusive license to make, use, sell, and offer for sale products covered by the licensed patents, including dihexa, the chemical compound into which ATH-1017 metabolizes following administration. To keep in good standing, the agreement requires the Company to meet certain development milestones and pay annual maintenance fees. All contractual requirements have been met as of September 30, 2021. During the year ended December 31, 2020, the Phase 2 clinical trial milestone had been reached and a payment of $ 50,000 to WSU was recorded. The Company may also be obligated to pay the following if the related milestones are reached:  $ 300,000 – At initiation of the first Phase 3 clinical trial in the United States, European Union or Japan for the first licensed product; and  $ 600,000 – Upon receipt of marketing approval in the United States, European Union or Japan for the first licensed product. Under the terms of the agreement, the Company will pay a royalty in the mid-single digits of net sales, with the first $ 100,000 of net sales being exempt from royalty payment, and annual minimum royalty payments of $ 25,000 beginning after the first commercial sale of a licensed product. As of September 30, 2021 , no net sales of any licensed products had occurred and the Company had no t incurred a royalty obligation under this agreement. Additionally, the agreement allows the Company to sublicense the rights conveyed by the agreement, subject to additional payments to WSU based upon the sublicense consideration received in such event. Such amounts are dependent on the terms of the underlying sublicense and range from the mid-single digits to mid-teens of any non-sales based payments received, and low twenties of net sales based sublicense royalties. As of September 30, 2021, the Company has not entered into or incurred any liability from a sublicense agreement. Grant Liability In 2014 and 2015, the Company received $ 250,000 and $ 500,000 , respectively, from LSDF under the terms of two matching grant award agreements. In connection with the agreements, LSDF retained the right to receive cash payments of 2.0 times the amounts received, or $ 1.5 million, upon the occurrence of specified triggering events, including:  receipt of license revenue, sales revenue, or consideration related to the underlying IP;  transfers the underlying IP without receiving consideration;  relocation of the Company from Washington state;  completion of an initial public offering;  a third-party acquisition of a controlling interest in the Company, and;  termination of the agreements. To appropriately capture the economics of this arrangement, the grant liability was accounted for under ASC 825-10, Financial Instruments − Overall . The estimated fair value of the grant liability was reassessed at each balance sheet date, with changes in fair value reflected in other income (expense), net. To determine the estimated fair value of the grant liability, the Company used a discounted cash flow simulation methodology that assigns probabilities to the timing and likelihood of each triggering event, a discount rate based on market data for securities with similar durations and credit ratings to the Company, and the expected payment amount. The assumptions used to calculate the fair value of the grant liability were subject to significant judgment, and payment may have been in an amount different from the liability that the Company estimated. However, total payments under the agreements would not exceed $ 1.5 million. The consummation of the Company’s IPO in September 2020 was a triggering event under the terms of the grant and the liability was remeasured to the pay-off amount of $ 1.5 million prior to settlement. The change in the fair value of the liability resulted in expense of approximately $ 464,000 for the year ended December 31, 2020, which was included in other income (expense), net in the accompanying consolidated statements of operations and comprehensive loss.

Convertible Notes

Convertible Notes	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Convertible Notes	8 . Convertible Notes The Company issued unsecured convertible notes with an aggregate principal amount of $ 1.7 million in 2020. Previously, the Company issued unsecured convertible notes with aggregate principal amounts of $ 0.9 million and $ 1.3 million and in 2019 and 2018, respectively. The notes accrued interest at a rate of 5 % per year and mature in December 2021 , unless earlier converted. No principal or interest was payable prior to maturity as the convertible notes and any accrued interest would automatically convert upon a qualified financing event at a conversion price equal to 85 % of the price per share of the qualified financing. Holders may have also elected to convert their notes to shares of common stock upon the maturity of the notes at the then fair value of common stock. If the Company experienced a change in control, holders may have either converted the outstanding principal amount plus any accrued interest into shares of common stock at the then fair value of common stock or may have required the Company to repurchase the notes in cash at a price equal to 200 % of the outstanding principal amount plus any accrued interest. Certain conversion and redemption features as described above were determined to be an embedded derivative requiring bifurcation and separate accounting in accordance with ASC 815, Derivatives and Hedging . The fair value of the embedded derivative was determined using a discounted cash flow simulation methodology that assigns probabilities to the timing and likelihood of each event. The discount rate was determined based on market interest rate data for securities with similar durations and credit ratings to the convertible notes. The fair value of the embedded derivative was recorded as a liability with an offsetting amount recorded as a discount on the convertible notes at each issuance. The discount is being amortized to interest expense using the effective interest method over the contractual term of the notes. In May 2020, the outstanding principal balance of the convertible notes of $ 3.8 million and accrued interest of $ 160,000 converted into 512,858 shares of Series B-1 convertible preferred stock. The excess of the carrying value of the convertible notes and the derivative liability over the fair value of the Series B-1 convertible preferred stock at conversion resulted in a gain upon extinguishment of $ 199,000 .

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9 . Commitments and Contingencies Legal Proceedings From time to time, we are subject to various legal proceedings or claims that arise in the ordinary course of business. We accrue a liability when management believes that it is both probable that a liability has been incurred and the amount of loss can be reasonably estimated, and as of September 30, 2021, we have not recorded any such liabilities. The following is a brief description of the more significant legal proceedings. Securities Class Actions On June 25, 2021 , plaintiffs Fan Wang and Hang Gao filed a putative securities class action lawsuit in the U.S. District Court for the Western District of Washington against the Company and the Company’s former Chief Executive Officer Dr. Leen Kawas, captioned Wang v. Athira Pharma, Inc., et al. , No. 2:21-cv-00861. Plaintiffs Wang and Gao assert claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and SEC Rule 10b-5, alleging that the defendants made materially false and misleading statements and omitted material adverse facts regarding the Company’s business. Specifically, the Wang plaintiffs allege that the Company failed to disclose to investors that certain research conducted by Dr. Kawas was allegedly tainted by scientific misconduct during her doctoral work at WSU, including the manipulation of data, and that as a result, the defendants’ positive statements about the Company’s business, operations, and prospects were materially misleading. The Wang plaintiffs seek unspecified compensatory and punitive damages, and reasonable costs and expenses, including attorneys’ fees. That same day, on June 25, 2021 , plaintiff Harshdeep Jawandha filed a putative securities class action lawsuit in the U.S. District Court for the Western District of Washington against the Company, Dr. Kawas, the Company’s Chief Financial Officer, certain members of the Company’s board of directors at the time of the Company’s IPO, as well as the IPO underwriters, captioned Jawandha v. Athira Pharma, Inc., et al. , No. 2:21-cv-00862. The Jawandha complaint asserts violations of Sections 11 and 15 of the Securities Act of 1933, alleging that that the Company’s IPO registration statement was materially false and misleading because it omitted to state that certain of Dr. Kawas’s published doctoral research papers at WSU contained allegedly improperly altered images, that the research was allegedly foundational to the Company’s efforts to develop treatments for Alzheimer’s disease, and that the defendants’ positive statements about the Company’s business, operations, and prospects were materially misleading. The plaintiff seeks unspecified compensatory damages, and reasonable costs and expenses, including attorneys’ fees. Also on June 25, 2021 , plaintiffs Timothy Slyne and Tai Slyne filed a putative securities class action lawsuit in the U.S. District Court for the Western District of Washington against the Company, Dr. Kawas, the Company’s Chief Financial Officer, and the same members of the Company’s board of directors and underwriters as in the Jawandha complaint, captioned Slyne v. Athira Pharma, Inc. et al. , No. 2:21-cv-00864. The Slyne complaint asserts violations of Sections 11 and 15 of the Securities Act of 1933, alleging that purported issues with Dr. Kawas’s doctoral research at WSU should have been disclosed in the Company’s IPO registration statement. The Slyne plaintiffs seek unspecified compensatory damages, reasonable costs and expenses, including attorneys’ fees, and injunctive and other equitable relief. On August 9, 2021, the Honorable Judge Thomas S. Zilly, the district judge presiding over Wang v. Athira Pharma, Inc., et al. , No. 2:21-cv-00861, issued an order consolidating the three cases under that case number and postponing a response from defendants until after the appointment of a lead plaintiff and the submission or designation of a consolidated complaint. On October 5, 2021, the district court issued an order appointing lead plaintiffs and approved their selection of lead and liaison counsel. The Company cannot predict the outcome of these suits, and failure by the Company to obtain a favorable resolution of these suits could have a material adverse effect on its business, results of operations and financial condition. The Company’s chances of success on the merits are still uncertain and any possible loss or range of loss cannot be reasonably estimated and as such the Company has not recorded a liability as of September 30, 2021. 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. Additionally, the Company has a lease agreement for laboratory and office facilities at the University of Washington in Seattle, Washington with an initial term of 12 months for which the Company recognizes expense on a straight-line basis within operating expenses. As of September 30, 2021, 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): September 30, Remaining 2021 $ 112 2022 452 2023 466 2024 480 2025 494 Thereafter 856 Total undiscounted lease payments 2,860 Present value adjustment for minimum lease commitments ( 593 ) Tenant improvement allowance receivable ( 280 ) Net lease liability $ 1,987 The weighted average remaining lease term and the weighted average discount rate used to determine the operating lease liability were as follows: September 30, Weighted average remaining lease term (years) 5.9 Weighted average discount rate 8.1 % Operating lease expense was $ 89,000 and $ 235,000 for the three and nine months ended September 30, 2021 , respectively. Variable lease expense was $ 33,000 and $ 73,000 for operating leases during the three and nine months ended September 30, 2021 , respectively. Rent expense recognized for short term leases was $ 3,000 and $ 18,000 for the three months ended September 30, 2021 and 2020 , respectively, and $ 16,000 and $ 57,000 for the nine months ended September 30, 2021 and 2020 , respectively.

Convertible Preferred Stock

Convertible Preferred Stock	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Convertible Preferred Stock	0 . Convertible Preferred Stock In May and June 2020, the Company issued an aggregate of 9,372,765 shares of its Series B convertible preferred stock at a purchase price of $ 9.12 per share for aggregate proceeds of $ 81.6 million, net of offering costs. The Company issued warrants to purchase 2,343,168 shares of its common stock, of which 688,067 were exercised concurrently with the shares of Series B convertible preferred stock issuance, for net proceeds of $ 55,000 . In addition, the Company issued warrants to purchase 127,481 shares of its Series B convertible preferred stock at a purchase price of $ 9.12 per share. The Series B convertible preferred stock financing triggered the automatic conversion of the Company’s outstanding convertible promissory notes into 512,858 shares of Series B-1 convertible preferred stock based on a price of $ 7.752 per share ( 85 % of the $ 9.12 original issuance price of the Series B convertible preferred stock). In September 2020, upon the consummation of the Company’s IPO, all outstanding shares of convertible preferred stock converted into 12,503,009 shares of common stock.

Common Stock

Common Stock	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Common Stock	11. 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: September 30, December 31, Shares issuable upon the exercise of outstanding 2,323,821 1,974,870 Shares available for future grant under the 2020 Equity 4,768,090 3,742,235 Shares available for future grant under the Employee 631,984 323,000 Total 7,723,895 6,040,105 The Company’s 2020 Equity Incentive Plan (“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 (a) 3,230,000 shares, (b) 5 % of the number of shares of common stock issued and outstanding on the immediately preceding December 31, or (c) an amount determined by the Company’s board of directors. The Company’s 2020 Employee Stock Purchase Plan (“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 (a) 646,000 shares, (b) 1 % of the number of shares of common stock issued and outstanding on the immediately preceding December 31, or (c) an amount determined by the Company’s board of directors. Effective January 1, 2021, the Company’s 2020 Plan and ESPP reserves increased by 1,624,259 shares and 324,851 shares, respectively. During the nine months ended September 30, 2021 , the Company issued 15,867 shares of common stock to service providers under the ESPP.

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based Compensation	12. Stock-based Compensation Stock‑based compensation expense recognized was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 266 $ 43 $ 811 $ 62 General and administrative 839 68 2,377 156 Total stock-based compensation expense $ 1,105 $ 111 $ 3,188 $ 218 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 grant date fair market value of the shares of common stock underlying stock options has historically been determined by the Company’s board of directors. Because previously there was no public market for the Company’s common stock, the board of directors exercised reasonable judgment and considered a number of objective and subjective factors to determine the best estimate of the fair market value, which include contemporaneous valuations performed by an independent third party, important developments in the Company’s operations, sales of convertible preferred stock, the rights, preferences and privileges of its convertible preferred stock relative to those of its common stock, lack of marketability of its common stock, actual operating results, financial performance, the progress of clinical development, the likelihood of achieving a liquidity event for its security holders, the trends, development and conditions in the life sciences and biotechnology sectors, the economy in general, and the stock price performance and volatility of comparable public companies.  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: Nine Months Ended September 30, 2021 2020 Risk-free interest rate 0.81 % 0.49 % Expected volatility 89.34 % 80.11 % Expected term (in years) 6.12 6.93 Expected dividend yield — — The weighted-average grant-date fair value of options granted to employees and directors during the nine months ended September 30, 2021 and 2020 was $ 10.2 million and $ 2.1 million, respectively. No options were granted to advisors during the nine months ended September 30, 2021. The weighted-average fair value of options granted to advisors during the nine months ended September 30, 2020 was $ 0.7 million. Stock Option Activity Changes in shares available for grant under the 2020 Plan during the nine months ended September 30, 2021 were as follows: Shares Shares available for grant at December 31, 2020 3,742,235 2020 Plan reserve increase on January 1, 2021 1,624,259 Options and restricted stock units granted ( 661,928 ) Options forfeited, cancelled, or expired 63,524 Shares available for grant at September 30, 2021 4,768,090 A summary of stock option activity under the 2020 Plan for the nine months ended September 30, 2021 was as follows: Shares Weighted- Weighted- Aggregate Balance at December 31, 2020 1,974,870 $ 9.31 7.98 $ 49,275 Granted 658,776 20.96 Exercised ( 246,301 ) 1.29 Forfeited/expired ( 63,524 ) 12.01 Balance at September 30, 2021 2,323,821 $ 13.39 7.73 $ 6,002 Expected to vest 1,504,872 $ 17.15 8.97 $ 1,387 Options exercisable 818,949 $ 6.48 5.45 $ 4,615 The total fair value of options granted to employees, directors, and advisors that vested during the nine months ended September 30, 2021 was $ 1.3 million, which included $ 1.0 million for options granted to employees and directors and $ 0.3 million for options granted to advisors. The total fair value of options that vested during the nine months ended September 30, 2020 was $ 219,000 , which included $ 144,000 for options granted to employees and directors and $ 75,000 for options granted to advisors. 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 September 30, 2021 . The aggregate intrinsic value of options exercised was $ 2.0 million and $ 9.4 million during the nine months ended September 30, 2021 and 2020, respectively, determined as of the date of option exercise. As of September 30, 2021 , there was $ 10.8 million of total unrecognized compensation cost related to unvested stock options. The Company expects to recognize this cost over a remaining weighted-average period of 1.64 years. The Company utilizes newly issued shares to satisfy option exercises. Stock options outstanding and exercisable under the 2020 Plan consisted of the following at September 30, 2021: Employees and Directors Non-employees Exercise Price ($) Shares Shares Shares Shares 0.16 to 1.00 226,980 226,980 — — 1.04 to 1.49 375,033 222,659 113,642 93,150 17.00 to 19.94 783,758 201,138 195,453 60,684 20.55 to 29.41 628,955 14,338 — — Total 2,014,726 665,115 309,095 153,834 Restricted Stock Award Activity In 2018, the Company issued a restricted stock award (“RSA”) to an advisor under the Company’s 2014 Equity Incentive Plan. The restricted stock award vests over three years and requires continued service to the Company during the vesting period. The vesting provisions of individual awards may vary as approved by the Company’s board of directors. If continued service terminates for any reason, the Company has the right to repurchase the unvested shares for no consideration. There were 4,204 shares subject to repurchase as of December 31, 2020, all of which were related to non-employee RSAs. A summary of RSA activity for the nine months ended September 30, 2021 is as follows: Share Weighted- Non-vested at December 31, 2020 4,204 $ 1.35 Granted — — Vested ( 4,204 ) 1.35 Non-vested at September 30, 2021 — $ — Restricted Stock Unit Activity During the nine months ended September 30, 2021, the Company issued a restricted stock unit (“RSU”) award to an advisor under the 2020 Plan. A summary of RSU activity for the nine months ended September 30, 2021 is as follows: Share Weighted- Non-vested at December 31, 2020 — $ — Granted 3,152 21.15 Vested ( 3,152 ) 21.15 Non-vested at September 30, 2021 — $ — In November 2021, the Company granted RSUs equivalent to 360,500 shares of the Company's common stock to employees under the 2020 Plan with a grant date fair value of $ 5.5 million. The RSUs will vest upon achievement of certain clinical development milestones, subject to continued service to the Company during the vesting period.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	13. 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: Nine Months Ended September 30, 2021 2020 Non-vested RSAs — 4,204 Stock options to purchase common stock 2,323,821 1,927,428 Employee stock purchase plan 2,584 — Total 2,326,405 1,931,632

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events Independent Special Committee Investigation On October 21, 2021, the Company announced that an independent special committee of the board of directors completed its internal investigation, which was originally announced in June 2021. The special committee, assisted by independent legal counsel, conducted an investigation of allegations raised regarding doctoral research by Dr. Leen Kawas, the Company's former Chief Executive Officer and one of its founders, conducted while at WSU, as well as related matters. The special committee's primary finding was that Dr. Kawas altered images in her 2011 doctoral dissertation and at least four research papers that she co-authored while a graduate student at WSU, and published from 2011 to 2014. Among its other findings, the special committee found that the Company's issued U.S. patent claiming ATH-1017, the Company's lead development candidate, does not cite any paper which the committee found to contain an image altered by Dr. Kawas. Though the committee found that the Company has cited challenged research papers relating to dihexa to support the activity of ATH-1017, a prodrug of dihexa, in certain other communications and applications, it also found that the Company has conducted alternative preclinical studies to support ATH-1017's activity and recently submitted those studies for peer review publication. Among its other findings, the special committee also found that WSU's dihexa patent incorporates images from papers co-authored by Dr. Kawas, certain of which were altered by Dr. Kawas. The Company understands that WSU is undertaking its own investigation into claims of potential misconduct involving research conducted by Dr. Kawas during her doctoral studies at WSU. The Company understands that this review is ongoing, and the Company cannot predict when WSU's investigation will be completed or what conclusions WSU will reach. The Company has filed a patent application claiming the composition of matter of ATH-1017 and methods of treatment using ATH-1017. The ATH-1017 composition of matter patent issued in the U.S. The ATH-1017 patent family is distinct from, and not part of the same patent family as, the dihexa patent licensed from WSU. The Company-owned patent covering ATH-1017 will expire no earlier than June 2037, and the WSU patent covering dihexa would normally expire by April 2032. Management Changes On October 18, 2021, Dr. Leen Kawas submitted her resignation as President and Chief Executive Officer of the Company and as a member of the Company's board of directors, effective October 18, 2021. Concurrently with Dr. Kawas's resignation, the Company's board of directors appointed Mark Litton, Ph.D., MBA as President and Chief Executive Officer, and Ms. Rachel Lenington, MBA, as Chief Operating Officer, each effective as of October 18, 2021. Dr. Litton was also appointed to the Company's board of directors. In connection with the cessation of Dr. Kawas's employment and pursuant to the terms of her separation agreement dated October 18, 2021 (the "Separation Agreement"), Dr. Kawas is eligible to receive severance benefits, including a lump sum equivalent to one year of her base salary of $ 510,000 . In addition, under the Separation Agreement, Dr. Kawas will retain previously granted options vested as of the effective date of the Separation Agreement for 363,535 shares of the Company's common stock. The Company recognized the financial impacts of Dr. Kawas' Separation Agreement in October 2021, as Dr. Kawas's resignation was submitted and effective after the date of these financial statements.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”). During the third quarter of 2020, the Company incorporated Athira Pharma Australia PTY LTD in Australia and since its creation, the Australian subsidiary’s financial position and results of operations are consolidated in the accompanying unaudited condensed consolidated financial statements.
Unaudited Interim Condensed Financial Statements	Unaudited Interim Condensed Consolidated Financial Statements The accompanying unaudited condensed consolidated balance sheet as of September 30, 2021, and condensed consolidated statements of operations and comprehensive loss, cash flows, and convertible preferred stock and stockholders’ (deficit) equity for the three and nine months ended September 30, 2021 and 2020, are unaudited. The balance sheet as of December 31, 2020 was derived from the audited consolidated financial statements as of and for the year ended December 31, 2020. The unaudited interim condensed consolidated financial statements have been prepared on a basis consistent with the audited annual financial statements as of and for the year ended December 31, 2020, and, in the opinion of management, reflect all adjustments, consisting solely of normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2021, and the condensed consolidated results of its operations and its cash flows for the three and nine months ended September 30, 2021 and 2020. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2021 and 2020 are also unaudited. The condensed consolidated results of operations for the three and nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the full year ending December 31, 2021 or any other period. These interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements as of and for the year ended December 31, 2020 included in its Annual Report on Form 10-K filed with the SEC on March 25, 2021.
Fair Value Measurements	Fair Value Measurements The carrying amounts of certain financial instruments, including cash, cash equivalents, investments, accounts payable and accrued expenses approximate their fair values due to the short-term nature of those amounts. The fair values of the grant liability to Washington Life Sciences Discovery Fund (“LSDF”), currently managed by the Washington State Department of Commerce, the derivative liability, and the convertible preferred stock warrant liability were estimated using level 3 unobservable inputs.
Convertible Preferred Stock Warrant Liability	Convertible Preferred Stock Warrant Liability Freestanding warrants to purchase shares of the Company’s convertible preferred stock were accounted for as liabilities at fair value, because the shares underlying the warrants contained contingent redemption features outside the control of the Company. Warrants classified as liabilities are recorded on the Company’s balance sheets at their fair value on the date of issuance and remeasured to fair value on each subsequent reporting period, with the changes in fair value recognized as a component of other income (expense), net in the accompanying statements of operations. The Company adjusted the liability for the final change in the fair value of these warrants immediately preceding their automatic exercise in connection with the Company’s initial public offering (“IPO”). Subsequent to the Company’s IPO, the corresponding liability was reclassified to additional paid in capital.
Grant Income	Grant Income Grant income in the accompanying statements of operations consisted of the following for the three and nine months ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Alzheimer's Association Part the Cloud $ — $ — $ — $ 22 National Institutes of Health Grant 2,079 — 6,499 — Total grant income $ 2,079 $ — $ 6,499 $ 22 Amounts recorded in the accompanying balance sheets as receivables from these granting agencies were as follows (in thousands): September 30, December 31, Alzheimer's Association Part the Cloud Research $ — $ 224 National Institutes of Health Grant 2,079 1,076 Total grant income $ 2,079 $ 1,300 In January 2019, the Alzheimer’s Association awarded the Company a $ 1.0 million Part the Cloud research grant. Grant proceeds must be used to advance the Company’s ATH-1017 product candidate in the Alzheimer’s disease setting. Reporting of expenses incurred supported by the grant as well as research updates are sent to the Alzheimer’s Association semi-annually. Under the terms of the agreement, the Company received $ 776,000 in 2019 and received the remaining $ 224,000 in March 2021 after having completed certain development milestones in October 2020. The Company recognized income related to the Part the Cloud research grant as qualifying expenses under the grant agreement were incurred. In December 2020, the Company accepted a grant from the National Institute on Aging (“NIA”) of the National Institutes of Health (“NIH”) to support its ACT-AD Phase 2 clinical trial for ATH-1017, the Company’s lead therapeutic candidate being developed for the treatment of individuals with mild-to-moderate Alzheimer’s disease. Under the terms of the agreement, the Company may potentially receive $ 7.8 million with the potential for an additional $ 7.4 million, up to an aggregate of $ 15.2 million. The Company recognizes income related to the NIH grant as qualifying expenses under the grant agreement are incurred. The Company received cash of $ 2.6 million and $ 5.5 million related to the NIH grant during the three and nine months ended September 30, 2021 , respectively.
Short-term and Long-term Investments	Short-term and Long-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, short-term investments, and long-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 or loss. Realized gains and losses on the sale of these securities are recognized in net loss. The Company periodically evaluates whether declines in fair values of its investments below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the investment until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any investment before recovery of its amortized cost basis. Factors considered include quoted market prices, recent financial results and operating trends, implied values from any recent transactions or offers of investee securities, credit quality of debt instrument issuers, other publicly available information that may affect the value of the investments, duration and severity of the decline in value, and our strategy and intentions for holding the investment.
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.
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 proprietary drug discovery platform (“ATH platform”). The Company’s drug discovery efforts and the development of its product 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.
Leases	Leases The Company adopted Accounting Standards Codification (“ASC”) Topic 842 - Leases , on July 1, 2020, 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 (“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, discussed in more detail below. 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 lease includes 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 lease. 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. 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 grants subject to performance-based milestone vesting using the accelerated attribution method over the remaining 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. The Company adopted Accounting Standards Update (“ASU”) 2018-07 as of January 1, 2020 . As a result, stock-based payments issued to non-employees prior to January 1, 2020 have been recorded at their fair values as of the transition date and are no longer subject to periodic adjustments as the underlying equity instruments vest. Any remaining compensation expense is recognized over the remaining vesting term on a straight-line basis, which reflects the service period, based on the fair value as of January 1, 2020.
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.
Segments	Segments The Company has determined that it operates and manages one operating segment, which is the business of developing and commercializing therapeutics. The Company’s chief operating decision maker, its chief executive officer, reviews financial information on an aggregate basis for the purpose of allocating resources.
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 (“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 (a) no longer an emerging growth company or (b) 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.
Recently Adopted Accounting Pronouncements Adopted and Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments: Credit Losses (Topic 326) as clarified in ASU 2019-04, ASU 2019-05, and ASU 2020-02. The objective of the standard is to provide information about expected credit losses on financial instruments at each reporting date and to change how other-than-temporary impairments on investment securities are recorded. The ASU will become effective beginning January 1, 2023, with early adoption permitted. The Company is currently evaluating the potential impacts of the ASU on its financial condition, results of operations, cash flows and financial statement disclosures. Although there were several other new accounting pronouncements issued or proposed by the FASB, the Company does not believe any of these have had or will have material impact on its condensed consolidated financial statements.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Grant Income in the Accompanying Statements of Operations	Grant income in the accompanying statements of operations consisted of the following for the three and nine months ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Alzheimer's Association Part the Cloud $ — $ — $ — $ 22 National Institutes of Health Grant 2,079 — 6,499 — Total grant income $ 2,079 $ — $ 6,499 $ 22
Summary of Amounts Recorded in the Accompanying Balance Sheets as Receivables from the Granting Agencies	Amounts recorded in the accompanying balance sheets as receivables from these granting agencies were as follows (in thousands): September 30, December 31, Alzheimer's Association Part the Cloud Research $ — $ 224 National Institutes of Health Grant 2,079 1,076 Total grant income $ 2,079 $ 1,300

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Cash Equivalents, Short-term Investments and Long-term Investments	The following tables reflect the Company’s financial asset balances measured on a recurring basis as of September 30, 2021 and December 31, 2020 (in thousands): September 30, 2021 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 72,487 $ — $ — $ 72,487 Commercial paper 2 21,763 — ( 1 ) 21,762 Total cash equivalents $ 94,250 $ — $ ( 1 ) $ 94,249 Short-term investments: Commercial paper 2 85,642 5 ( 5 ) 85,642 U.S. government debt and agency 2 40,858 11 — 40,869 Corporate bonds 2 1,936 — — 1,936 Total short-term investments $ 128,436 $ 16 $ ( 5 ) $ 128,447 Long-term investments: Corporate bonds 2 3,308 — ( 4 ) 3,304 U.S. government debt and agency 2 100,347 17 ( 19 ) 100,345 Total long-term investments $ 103,655 $ 17 $ ( 23 ) $ 103,649 December 31, 2020 Level Amortized Unrealized Unrealized Fair Cash equivalents: Money market fund 1 $ 5 $ — $ — $ 5 Commercial paper 2 44,318 — ( 2 ) 44,316 U.S. government debt and agency 2 4,999 — — 4,999 U.S. treasury bills 2 4,450 — — 4,450 Total cash equivalents $ 53,772 $ — $ ( 2 ) $ 53,770 Short-term investments: Commercial paper 2 77,272 1 ( 4 ) 77,269 U.S. government debt and agency 2 31,835 7 — 31,842 U.S. treasury bills 2 14,029 — ( 3 ) 14,026 Corporate bonds 2 920 — — 920 Total short-term investments $ 124,056 $ 8 $ ( 7 ) $ 124,057 Long-term investments: U.S. government debt and agency 2 78,924 32 — 78,956 U.S. treasury bills 2 4,551 2 — 4,553 Total long-term investments $ 83,475 $ 34 $ — $ 83,509

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2021
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment as of September 30, 2021 and December 31, 2020 consisted of the following (in thousands): September 30, December 31, Lab equipment $ 268 $ 81 Office furniture, fixtures, and 325 — Leasehold improvement 2,563 — Construction in progress 302 2,639 Property and equipment, at cost 3,458 2,720 Less: accumulated depreciation ( 397 ) ( 71 ) Property and equipment, net $ 3,061 $ 2,649

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): September 30, December 31, Employee compensation and benefits $ 1,408 $ 1,624 Research and development expenses 5,332 1,169 Professional services and other 1,408 330 Total accrued liabilities $ 8,148 $ 3,123

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	9 Months Ended
	Sep. 30, 2021
Other Income And Expenses [Abstract]
Schedule of Other Income (Expense), Net	Other income (expense), net consisted of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Interest and other income $ 74 $ 35 $ 232 $ 45 Interest expense ( 1 ) — ( 1 ) ( 366 ) Change in fair value of derivative liability — — — ( 132 ) Change in fair value of grant liability — ( 453 ) — ( 464 ) Change in convertible preferred stock — ( 641 ) ( 641 ) Gain on extinguishment of convertible notes — — — 199 Total other income (expense), net $ 73 $ ( 1,059 ) $ 231 $ ( 1,359 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
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): September 30, Remaining 2021 $ 112 2022 452 2023 466 2024 480 2025 494 Thereafter 856 Total undiscounted lease payments 2,860 Present value adjustment for minimum lease commitments ( 593 ) Tenant improvement allowance receivable ( 280 ) Net lease liability $ 1,987
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: September 30, Weighted average remaining lease term (years) 5.9 Weighted average discount rate 8.1 %

Common Stock (Tables)

Common Stock (Tables)	9 Months Ended
	Sep. 30, 2021
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: September 30, December 31, Shares issuable upon the exercise of outstanding 2,323,821 1,974,870 Shares available for future grant under the 2020 Equity 4,768,090 3,742,235 Shares available for future grant under the Employee 631,984 323,000 Total 7,723,895 6,040,105

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Stock-based Compensation Expense Recognized	Stock‑based compensation expense recognized was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 266 $ 43 $ 811 $ 62 General and administrative 839 68 2,377 156 Total stock-based compensation expense $ 1,105 $ 111 $ 3,188 $ 218
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: Nine Months Ended September 30, 2021 2020 Risk-free interest rate 0.81 % 0.49 % Expected volatility 89.34 % 80.11 % Expected term (in years) 6.12 6.93 Expected dividend yield — —
Summary of Option Activity Changes in Shares Available for Grant under the 2020 Plan	Changes in shares available for grant under the 2020 Plan during the nine months ended September 30, 2021 were as follows: Shares Shares available for grant at December 31, 2020 3,742,235 2020 Plan reserve increase on January 1, 2021 1,624,259 Options and restricted stock units granted ( 661,928 ) Options forfeited, cancelled, or expired 63,524 Shares available for grant at September 30, 2021 4,768,090
Summary of Option Activity under the 2020 Plan	A summary of stock option activity under the 2020 Plan for the nine months ended September 30, 2021 was as follows: Shares Weighted- Weighted- Aggregate Balance at December 31, 2020 1,974,870 $ 9.31 7.98 $ 49,275 Granted 658,776 20.96 Exercised ( 246,301 ) 1.29 Forfeited/expired ( 63,524 ) 12.01 Balance at September 30, 2021 2,323,821 $ 13.39 7.73 $ 6,002 Expected to vest 1,504,872 $ 17.15 8.97 $ 1,387 Options exercisable 818,949 $ 6.48 5.45 $ 4,615
Summary of Stock Options Outstanding and Exercisable under the 2020 Plan	Stock options outstanding and exercisable under the 2020 Plan consisted of the following at September 30, 2021: Employees and Directors Non-employees Exercise Price ($) Shares Shares Shares Shares 0.16 to 1.00 226,980 226,980 — — 1.04 to 1.49 375,033 222,659 113,642 93,150 17.00 to 19.94 783,758 201,138 195,453 60,684 20.55 to 29.41 628,955 14,338 — — Total 2,014,726 665,115 309,095 153,834
Restricted Stock Award (RSA)
Summary of Restricted Stock Activity	A summary of RSA activity for the nine months ended September 30, 2021 is as follows: Share Weighted- Non-vested at December 31, 2020 4,204 $ 1.35 Granted — — Vested ( 4,204 ) 1.35 Non-vested at September 30, 2021 — $ —
Restricted Stock Units (RSUs)
Summary of Restricted Stock Activity	A summary of RSU activity for the nine months ended September 30, 2021 is as follows: Share Weighted- Non-vested at December 31, 2020 — $ — Granted 3,152 21.15 Vested ( 3,152 ) 21.15 Non-vested at September 30, 2021 — $ —

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2021
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: Nine Months Ended September 30, 2021 2020 Non-vested RSAs — 4,204 Stock options to purchase common stock 2,323,821 1,927,428 Employee stock purchase plan 2,584 — Total 2,326,405 1,931,632

Description of Business - Addit

Description of Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		9 Months Ended
	Feb. 28, 2021	Jan. 31, 2021	Sep. 30, 2021
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			$ 407.4
Cash, cash equivalents, and investments			$ 339.4
Follow-on Public Offering
Description Of Business [Line Items]
Number of shares issued and sold		4,000,000
Public offering price per share		$ 22.50
Net proceeds from public offering		$ 84.1
Underwriters’ Option
Description Of Business [Line Items]
Number of shares issued and sold	600,000
Public offering price per share	$ 22.50
Net proceeds from public offering	$ 12.7

Significant Accounting Polici_4

Significant Accounting Policies - Summary of Grant Income in the Accompanying Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Basis Of Presentation And Significant Accounting Policies [Line Items]
Grant income	$ 2,079	$ 6,499	$ 22
Alzheimer's Association Part the Cloud Research Grant
Basis Of Presentation And Significant Accounting Policies [Line Items]
Grant income			$ 22
National Institutes of Health Grant
Basis Of Presentation And Significant Accounting Policies [Line Items]
Grant income	$ 2,079	$ 6,499

Significant Accounting Polici_5

Significant Accounting Policies - Summary of Amounts Recorded in the Accompanying Balance Sheets as Receivables from the Granting Agencies (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Basis Of Presentation And Significant Accounting Policies [Line Items]
Unbilled grant receivable	$ 2,079	$ 1,300
Alzheimer's Association Part the Cloud Research Grant
Basis Of Presentation And Significant Accounting Policies [Line Items]
Unbilled grant receivable		224
National Institutes of Health Grant
Basis Of Presentation And Significant Accounting Policies [Line Items]
Unbilled grant receivable	$ 2,079	$ 1,076

Significant Accounting Polici_6

Significant Accounting Policies - Additional Information (Details)	1 Months Ended	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2021USD ($)	Mar. 31, 2021USD ($)	Sep. 30, 2021USD ($)Segment	Dec. 31, 2019USD ($)	Jan. 31, 2019USD ($)
Basis Of Presentation And Significant Accounting Policies [Line Items]
Number of operating segments | Segment				1
ASU 2016-02
Basis Of Presentation And Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020		Jan. 1, 2020
ASU 2018-07
Basis Of Presentation And Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted		true		true
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020		Jan. 1, 2020
National Institutes of Health Grant
Basis Of Presentation And Significant Accounting Policies [Line Items]
Grants received		$ 2,600,000		$ 5,500,000
Alzheimers Association
Basis Of Presentation And Significant Accounting Policies [Line Items]
Research grant awarded						$ 1,000,000
Grants received			$ 224,000		$ 776,000
National Institute on Aging of the National Institutes of Health
Basis Of Presentation And Significant Accounting Policies [Line Items]
Research grant awarded	$ 15,200,000
Grants received	7,800,000
Remaining grant to be received	$ 7,400,000

Fair Value - Schedule of Fair V

Fair Value - Schedule of Fair Value of Cash Equivalents, Short-term Investments and Long-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	$ 107,328	$ 60,625
Recurring Basis | Cash Equivalents
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	94,250	53,772
Cash equivalents, Unrealized Losses	(1)	(2)
Cash equivalents, Fair Value	94,249	53,770
Recurring Basis | Cash Equivalents | Money Market Fund | Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	72,487	5
Cash equivalents, Fair Value	72,487	5
Recurring Basis | Cash Equivalents | Commercial Paper | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	21,763	44,318
Cash equivalents, Unrealized Losses	(1)	(2)
Cash equivalents, Fair Value	21,762	44,316
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		4,999
Cash equivalents, Fair Value		4,999
Recurring Basis | Cash Equivalents | U.S. Treasury Bills | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost		4,450
Cash equivalents, Fair Value		4,450
Recurring Basis | Short-term Investments
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	128,436	124,056
Investments, Unrealized Gains	16	8
Investments, Unrealized Losses	(5)	(7)
Investments, Fair Value	128,447	124,057
Recurring Basis | Short-term Investments | Commercial Paper | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	85,642	77,272
Investments, Unrealized Gains	5	1
Investments, Unrealized Losses	(5)	(4)
Investments, Fair Value	85,642	77,269
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	40,858	31,835
Investments, Unrealized Gains	11	7
Investments, Fair Value	40,869	31,842
Recurring Basis | Short-term Investments | Corporate Bonds | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	1,936	920
Investments, Fair Value	1,936	920
Recurring Basis | Short-term Investments | U.S. Treasury Bills | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost		14,029
Investments, Unrealized Losses		(3)
Investments, Fair Value		14,026
Recurring Basis | Long Term Investments
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	103,655	83,475
Investments, Unrealized Gains	17	34
Investments, Unrealized Losses	(23)
Investments, Fair Value	103,649	83,509
Recurring Basis | Long Term Investments | U.S. Government Debt and Agency Securities | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	100,347	78,924
Investments, Unrealized Gains	17	32
Investments, Unrealized Losses	(19)
Investments, Fair Value	100,345	78,956
Recurring Basis | Long Term Investments | Corporate Bonds | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	3,308
Investments, Unrealized Losses	(4)
Investments, Fair Value	$ 3,304
Recurring Basis | Long Term Investments | U.S. Treasury Bills | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost		4,551
Investments, Unrealized Gains		2
Investments, Fair Value		$ 4,553

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - Recurring Basis	9 Months Ended
	Sep. 30, 2021
Minimum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term investments effective maturity date	1 year
Maximum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Short-term investments effective maturity date	1 year
Long-term investments effective maturity date	2 years

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 3,458	$ 2,720
Less: accumulated depreciation	(397)	(71)
Property and equipment, net	3,061	2,649
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	268	81
Office Furniture, Fixtures, and Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	325
Leasehold Improvement
Property Plant And Equipment [Line Items]
Property and equipment, at cost	2,563
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 302	$ 2,639

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Depreciation expense	$ 123,000	$ 0	$ 353,000	$ 0

Accrued Liabilities - Schedule

Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Employee compensation and benefits	$ 1,408	$ 1,624
Research and development expenses	5,332	1,169
Professional services and other	1,408	330
Total accrued Liabilities	$ 8,148	$ 3,123

Other Income (Expense), Net - S

Other Income (Expense), Net - Schedule of Other Income (Expense), Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Income And Expenses [Abstract]
Interest and other income	$ 74	$ 35	$ 232	$ 45
Interest expense	(1)		(1)	(366)
Change in fair value of derivative liability				(132)
Change in fair value of grant liability		(453)		(464)
Change in convertible preferred stock warrant liability		(641)		(641)
Gain on extinguishment of convertible notes				199
Total other income (expense), net	$ 73	$ (1,059)	$ 231	$ (1,359)

Significant Agreements - Additi

Significant Agreements - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2015	Dec. 31, 2014
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Change in fair value of grant liability	$ 453,000		$ 464,000
Washington State University License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments payable upon marketing approval					$ 600,000
Annual minimum royalty payments					25,000
Net sales exempt from royalty payment					100,000
Royalty obligation		$ 0
Washington State University License Agreement | Licensed Products
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Net sales		$ 0
Washington State University License Agreement | Phase 2 Clinical Trial Initiation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments on development milestone achieved				$ 50,000
Washington State University License Agreement | Phase 3 Clinical Trial Initiation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments, amount payable					300,000
Washington Life Services Discovery Fund Grant Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant received					500,000	$ 250,000
Grant liability payable amount, maximum					$ 1,500,000
Estimated fair value of the grant liability	$ 1,500,000		$ 1,500,000
Washington Life Services Discovery Fund Grant Agreement | Other Income (Expense), Net
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Change in fair value of grant liability				$ 464,000

Convertible Notes - Additional

Convertible Notes - Additional Information (Details) - USD ($)	1 Months Ended	9 Months Ended
	May 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Gain on extinguishment of debt			$ 199,000
Unsecured Convertible Notes
Debt Instrument [Line Items]
Debt instrument, principal amount		$ 1,700,000		$ 900,000	$ 1,300,000
Debt instrument, interest rate		5.00%
Debt instrument, maturity month and year		2021-12
Debt instrument, payment terms		No principal or interest was payable prior to maturity as the convertible notes and any accrued interest would automatically convert upon a qualified financing event at a conversion price equal to 85% of the price per share of the qualified financing.
Debt instrument, conversion price, percentage		85.00%
Debt instrument, repurchase price, percentage		200.00%
Debt conversion, converted instrument, amount	$ 3,800,000
Debt instrument, accrued interest	160,000
Gain on extinguishment of debt	$ 199,000
Unsecured Convertible Notes | Series B-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Debt conversion, converted instrument, shares issued	512,858

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Commitments And Contingencies [Line Items]
Operating lease expense	$ 89,000		$ 235,000
Variable lease expense	33,000		73,000
Short term leases, rent expense	$ 3,000	$ 18,000	$ 16,000	$ 57,000
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
Laboratory and Office Facilities | Bothell, Washington | Minimum [Member]
Commitments And Contingencies [Line Items]
Operating lease initial term	6 years 3 months 18 days		6 years 3 months 18 days
Laboratory and Office Facilities | Bothell, Washington | Maximum [Member]
Commitments And Contingencies [Line Items]
Operating lease initial term	7 years		7 years
Laboratory and Office Facilities | University of Washington, Seattle
Commitments And Contingencies [Line Items]
Operating lease initial term	12 months		12 months
Wang V. Athira Pharma Inc.,
Commitments And Contingencies [Line Items]
Lawsuit filing date			June 25, 2021
Name of plaintiff			Fan Wang and Hang Gao
Jawandha V. Athira Pharma Inc.,
Commitments And Contingencies [Line Items]
Lawsuit filing date			June 25, 2021
Name of plaintiff			Harshdeep Jawandha
Slyne V. Athira Pharma Inc.,
Commitments And Contingencies [Line Items]
Lawsuit filing date			June 25, 2021
Name of plaintiff			Timothy Slyne and Tai Slyne

Commitments and Contingencies_2

Commitments and Contingencies - Reconciliation of Undiscounted Operating Lease Cash Flows to Operating Lease Liability Payments (Details) $ in Thousands	Sep. 30, 2021USD ($)
Commitments And Contingencies Disclosure [Abstract]
Remaining 2021	$ 112
2022	452
2023	466
2024	480
2025	494
Thereafter	856
Total undiscounted lease payments	2,860
Present value adjustment for minimum lease commitments	(593)
Tenant improvement allowance receivable	(280)
Net lease liability	$ 1,987

Commitments and Contingencies_3

Commitments and Contingencies - Weighted Average Remaining Lease Term and Weighted Average Discount Rate to Determine the Operating Lease Liability (Details)	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Weighted average remaining lease term (years)	5 years 10 months 24 days
Weighted average discount rate	8.10%

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($)	2 Months Ended	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Class Of Stock [Line Items]
Convertible preferred stock terms of conversion		The Series B convertible preferred stock financing triggered the automatic conversion of the Company’s outstanding convertible promissory notes into 512,858 shares of Series B-1 convertible preferred stock based on a price of $7.752 per share (85% of the $9.12 original issuance price of the Series B convertible preferred stock).
Common Stock | IPO
Class Of Stock [Line Items]
Convertible preferred stock shares issued upon conversion			12,503,009
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Shares issued	9,372,765
Purchase price per share	$ 9.12
Proceeds from issuance of convertible preferred stock	$ 81,600,000
Warrants to purchase preferred stock	2,343,168
Warrants to purchase preferred stock exercised	688,067
Convertible preferred stock issuance for net proceeds	$ 55,000
Series B Convertible Preferred Stock | Purchase Price $1.15 Per Share
Class Of Stock [Line Items]
Warrants to purchase preferred stock	127,481
Class of warrant or right, exercise price	$ 9.12
Series B-1 Convertible Preferred Stock
Class Of Stock [Line Items]
Class of warrant or right, exercise price	$ 9.12
Convertible preferred stock shares issued upon conversion	512,858
Convertible preferred stock conversion price	$ 7.752
Convertible preferred stock conversion price percentage	85.00%

Common Stock - Schedule of Rese

Common Stock - Schedule of Reserved Shares of Common Stock for Future Issuance (Details) - shares	Sep. 30, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	7,723,895	6,040,105
Shares Issuable Upon the Exercise of Outstanding Common Stock Options
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	2,323,821	1,974,870
Shares available for Future Grant under 2020 Equity Incentive Plan
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	4,768,090	3,742,235
Shares available for Future Grant under Employee Stock Purchase Plan
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance	631,984	323,000

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - shares	3 Months Ended	9 Months Ended
	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Reserved shares of common stock for future issuance		7,723,895	6,040,105
Common Stock
Class Of Stock [Line Items]
Issued common stock, share under employee stock purchase plan	15,867	15,867
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		5.00%
Reserved shares of common stock for future issuance		1,624,259
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		1.00%
Reserved shares of common stock for future issuance		324,851

Stock-based Compensation - Stoc

Stock-based Compensation - Stock-based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,105	$ 111	$ 3,188	$ 218
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	266	43	811	62
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 839	$ 68	$ 2,377	$ 156

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	9 Months Ended
	Nov. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield		0.00%
Fair value of options vested		$ 1,300,000	$ 219,000
Aggregate intrinsic value of options exercised		2,000,000	9,400,000
Unrecognized compensation cost		$ 10,800,000
Remaining weighted-average period expected to recognize unrecognized compensation cost		1 year 7 months 20 days
Restricted Stock Award (RSA)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period		3 years
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted, shares		3,152
Forecast | Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted, shares	360,500
Fair value of options granted	$ 5,500,000
Employees and Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant-date fair value of options granted		$ 10,200,000	2,100,000
Fair value of options vested		1,000,000	144,000
Advisors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant-date fair value of options granted		0	700,000
Fair value of options vested		$ 300,000	$ 75,000
Non-employees | Restricted Stock Award (RSA)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares subject to repurchase upon discontinued service				4,204

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)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	0.81%	0.49%
Expected volatility	89.34%	80.11%
Expected term (in years)	6 years 1 month 13 days	6 years 11 months 4 days
Expected dividend yield	0.00%

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Option Activity Changes in Shares Available for Grant under the 2020 Plan (Details)	9 Months Ended
	Sep. 30, 2021shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Available for Grant, Beginning Balance	3,742,235
2020 Plan reserve increase on January 1, 2021	1,624,259
Options and restricted stock units granted	(661,928)
Options forfeited, cancelled, or expired	63,524
Available for Grant, Ending Balance	4,768,090

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Option Activity under the 2020 Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Beginning Balance	1,974,870
Shares, Granted	658,776
Shares, Exercised	(246,301)
Shares, Forfeited/expired	(63,524)
Shares, Ending Balance	2,323,821	1,974,870
Shares, Expected to vest	1,504,872
Shares, Options exercisable	818,949
Weighted-Average Exercise price per Share, Beginning Balance	$ 9.31
Weighted-Average Exercise price per Share, Granted	20.96
Weighted-Average Exercise price per Share, Exercised	1.29
Weighted-Average Exercise price per Share, Forfeited/expired	12.01
Weighted-Average Exercise price per Share, Ending Balance	13.39	$ 9.31
Weighted-Average Exercise price per Share, Expected to vest	17.15
Weighted-Average Exercise price per Share, Options exercisable	$ 6.48
Weighted-Average Remaining Contractual Term (in years)	7 years 8 months 23 days	7 years 11 months 23 days
Weighted-Average Remaining Contractual Term, Expected to vest (in years)	8 years 11 months 19 days
Weighted-Average Remaining Contractual Term, Options exercisable (in years)	5 years 5 months 12 days
Aggregate Intrinsic Value, Beginning Balance	$ 6,002	$ 49,275
Aggregate Intrinsic Value, Expected to vest	1,387
Aggregate Intrinsic Value, Options exercisable	$ 4,615

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Stock Options Outstanding and Exercisable under the 2020 Plan (Details) - $ / shares	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	2,323,821	1,974,870
Shares Exercisable	818,949
Employees and Directors
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	2,014,726
Shares Exercisable	665,115
Non-employees
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	309,095
Shares Exercisable	153,834
Exercise Price $0.16 to 1.00 | Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 0.16
Exercise Price $0.16 to 1.00 | Maximum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 1
Exercise Price $0.16 to 1.00 | Employees and Directors
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	226,980
Shares Exercisable	226,980
Exercise Price $1.04 to 1.49 | Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 1.04
Exercise Price $1.04 to 1.49 | Maximum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 1.49
Exercise Price $1.04 to 1.49 | Employees and Directors
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	375,033
Shares Exercisable	222,659
Exercise Price $1.04 to 1.49 | Non-employees
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	113,642
Shares Exercisable	93,150
Exercise Price $17.00 to 19.94 | Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 17
Exercise Price $17.00 to 19.94 | Maximum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price ($)	$ 19.94
Exercise Price $17.00 to 19.94 | Employees and Directors
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	783,758
Shares Exercisable	201,138
Exercise Price $17.00 to 19.94 | Non-employees
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	195,453
Shares Exercisable	60,684
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
Exercise Price $20.55 to 29.41 | Employees and Directors
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Shares Outstanding	628,955
Shares Exercisable	14,338

Stock-based Compensation - Su_4

Stock-based Compensation - Summary of Restricted Stock Activity (Details)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Restricted Stock Award (RSA)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested at December 31, 2020 | shares	4,204
Vested | shares	(4,204)
Weighted-Average Grant Date Fair Value, Non-vested, Beginning Balance | $ / shares	$ 1.35
Weighted-Average Grant Date Fair Value, Non-vested, Vested | $ / shares	$ 1.35
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share granted | shares	3,152
Vested | shares	(3,152)
Weighted-Average Grant Date Fair Value, Non-vested, Granted | $ / shares	$ 21.15
Weighted-Average Grant Date Fair Value, Non-vested, Vested | $ / shares	$ 21.15

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	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
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	2,326,405	1,931,632
Non-vested RSAs
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		4,204
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	2,323,821	1,927,428
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	2,584

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Subsequent Event	Oct. 18, 2021USD ($)shares
Subsequent Event [Line Items]
Severance benefits recognized | $	$ 510,000
Separation Agreement
Subsequent Event [Line Items]
Number of shares vested | shares	363,535
Date of separation agreement	Oct. 18, 2021