aTyr Pharma (ATYR) 10-K 14 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2022	Mar. 10, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Document Annual Report	true
Document Transition Report	false
Security Exchange Name	NASDAQ
Trading Symbol	LIFE
Entity Registrant Name	ATYR PHARMA, INC.
Entity Central Index Key	0001339970
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Common Stock, Shares Outstanding		53,162,052
Entity Public Float			$ 77,194,107
Entity File Number	001-37378
Entity Tax Identification Number	20-3435077
Entity Address, Address Line One	10240 Sorrento Valley Road
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Incorporation, State or Country Code	DE
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	731-8389
Title of 12(b) Security	Common Stock, par value $0.001 per share
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement to be filed with the Securities and Exchange Commission (SEC), pursuant to Regulation 14A in connection with the registrant’s 2023 Annual Meeting of Stockholders, which will be filed subsequent to the date hereof, are incorporated by reference into Part III of this Annual Report on Form 10-K. Such proxy statement will be filed with the SEC not later than 120 days following the end of the registrant’s fiscal year ended December 31, 2022
Auditor Name	Ernst & Young LLP
Auditor Location	San Diego, California
Auditor Firm ID	42

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 9,981	$ 2,336
Available-for-sale investments	56,165	105,575
Other receivables	11,775	435
Prepaid expenses	2,950	5,223
Total current assets	80,871	113,569
Restricted cash	3,165	0
Property and equipment, net	3,059	543
Operating lease, right-of-use assets	7,250	1,267
Financing lease, right-of-use assets	1,248	0
Other assets	193	158
Total assets	95,786	115,537
Current liabilities:
Accounts payable	3,106	1,031
Accrued expenses	9,862	4,002
Current portion of operating lease liability	630	980
Current portion of financing lease liability	264	0
Total current liabilities	13,862	6,013
Long-term operating lease liability, net of current portion	9,633	398
Long-term financing lease liability, net of current portion	1,007	0
Commitments and contingencies (Note 6)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 undesignated authorized shares as of December 31, 2022 and 2021, respectively; no shares issued or outstanding as of December 31, 2022 and 2021, respectively
Common stock, $0.001 par value per share; 85,000,000 and 42,500,000 authorized shares as of December 31, 2022 and 2021, respectively; issued and outstanding shares - 29,498,488 and 27,793,035 as of December 31, 2022 and 2021, respectively	29	28
Additional paid-in capital	489,502	481,832
Accumulated other comprehensive loss	(433)	(263)
Accumulated deficit	(417,634)	(372,296)
Total aTyr Pharma stockholders’ equity	71,464	109,301
Noncontrolling interest in Pangu BioPharma Limited	(180)	(175)
Total stockholders' equity	71,284	109,126
Total liabilities and stockholders’ equity	$ 95,786	$ 115,537

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	85,000,000	42,500,000
Common stock, shares issued	29,498,488	27,793,035
Common stock, shares outstanding	29,498,488	27,793,035

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues:
Total revenues	$ 10,386		$ 10,455
Operating expenses:
Research and development	42,808	$ 23,264	17,291
General and administrative	13,982	10,751	9,075
Total operating expenses	56,790	34,015	26,366
Loss from operations	(46,404)	(34,015)	(15,911)
Total other income (expense), net	1,061	238	(319)
Consolidated net loss	(45,343)	(33,777)	(16,230)
Net loss attributable to noncontrolling interest in Pangu BioPharma Limited	5	9	6
Net loss attributable to aTyr Pharma, Inc.	$ (45,338)	$ (33,768)	$ (16,224)
Net loss per share - basic	$ (1.60)	$ (1.77)	$ (1.77)
Net loss per share - diluted	$ (1.60)	$ (1.77)	$ (1.77)
Shares used in computing net loss per share, basic	28,419,569	19,080,878	9,160,269
Shares used in computing net loss per share, diluted	28,419,569	19,080,878	9,160,269
License and Collaboration Revenues [Member]
Revenues:
Total revenues	$ 10,386		$ 10,455

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Consolidated net loss	$ (45,343)	$ (33,777)	$ (16,230)
Other comprehensive loss:
Change in unrealized loss on available-for-sale investments, net of tax	(170)	(220)	(3)
Comprehensive loss	(45,513)	(33,997)	(16,233)
Comprehensive loss attributable to noncontrolling interest in Pangu BioPharma Limited	5	9	6
Comprehensive loss attributable to aTyr Pharma, Inc. common stockholders	$ (45,508)	$ (33,988)	$ (16,227)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Other Comprehensive Gain/(Loss) [Member]	Accumulated Deficit [Member]	Noncontrolling Interest [Member]	Convertible Preferred Stock Preferred Stock
Beginning balance at Dec. 31, 2019	$ 21,026	$ 4	$ 343,524	$ (40)	$ (322,304)	$ (160)	$ 2
Beginning balance, Shares at Dec. 31, 2019		3,891,787					1,643,961
Conversion of preferred stock to common stock		$ 1	1				$ (2)
Conversion of preferred stock to common stock, shares		587,444					(1,643,961)
Issuance of common stock from underwritten follow-on offering, net of offering costs	18,779	$ 4	18,775
Issuance of common stock from underwritten follow-on offering, net of offering costs, Shares		4,870,588
Issuance of common stock upon release of restricted stock units, Shares		8,678
Issuance of common stock pursuant to employee stock purchase plan	10		10
Issuance of common stock pursuant to employee stock purchase plan, Shares		3,382
Issuance of common stock from at-the-market offerings, net of offering costs	6,437	$ 2	6,435
Issuance of common stock from at the market offerings, net of offering costs, Shares		1,657,075
Stock-based compensation	1,465		1,465
Net unrealized loss on investments, net of tax	(3)			(3)
Net loss	(16,230)				(16,224)	(6)
Ending balance at Dec. 31, 2020	31,484	$ 11	370,210	(43)	(338,528)	(166)
Ending balance, Shares at Dec. 31, 2020		11,018,954
Issuance of common stock from underwritten follow-on offering, net of offering costs	80,646	$ 11	80,635
Issuance of common stock from underwritten follow-on offering, net of offering costs, Shares		10,781,250
Issuance of common stock upon release of restricted stock units, Shares		4,177
Issuance of common stock upon exercise of stock options	62		62
Issuance of common stock upon exercise of stock options, Shares		10,751
Issuance of common stock pursuant to employee stock purchase plan	11		11
Issuance of common stock pursuant to employee stock purchase plan, Shares		3,382
Issuance of common stock from at-the-market offerings, net of offering costs	14,070	$ 3	14,067
Issuance of common stock from at the market offerings, net of offering costs, Shares		2,974,521
Issuance of common stock from committed purchase agreement, net of offering costs	15,236	$ 3	15,233
Issuance of common stock from committed purchase agreement, net of offering costs, Shares		3,000,000
Stock-based compensation	1,614		1,614
Net unrealized loss on investments, net of tax	(220)			(220)
Net loss	(33,777)				(33,768)	(9)
Ending balance at Dec. 31, 2021	109,126	$ 28	481,832	(263)	(372,296)	(175)
Ending balance, Shares at Dec. 31, 2021		27,793,035
Issuance of common stock upon release of restricted stock units, Shares		2,500
Issuance of common stock upon exercise of stock options	$ 1		1
Issuance of common stock upon exercise of stock options, Shares	259	259
Issuance of common stock pursuant to employee stock purchase plan	$ 44		44
Issuance of common stock pursuant to employee stock purchase plan, Shares		20,612
Issuance of common stock from at-the-market offerings, net of offering costs	5,472	$ 1	5,471
Issuance of common stock from at the market offerings, net of offering costs, Shares		1,682,082
Stock-based compensation	2,154		2,154
Net unrealized loss on investments, net of tax	(170)			(170)
Net loss	(45,343)				(45,338)	(5)
Ending balance at Dec. 31, 2022	$ 71,284	$ 29	$ 489,502	$ (433)	$ (417,634)	$ (180)
Ending balance, Shares at Dec. 31, 2022		29,498,488

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Consolidated net loss	$ (45,343)	$ (33,777)	$ (16,230)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	232	475	569
Stock-based compensation	2,154	1,614	1,465
Debt discount accretion and non-cash interest expense	0	0	346
Amortization of premium of available-for-sale investment securities	533	366	110
Amortization of right-of-use assets	1,463	829	697
Gain (loss) on disposal of property and equipment	(92)	6	3
Changes in operating assets and liabilities:
Other receivables	(11,923)	1,604	(1,939)
Prepaid expenses and other assets	2,238	(3,378)	(1,122)
Accounts payable and accrued expenses	6,741	47	1,763
Contract liability	0	0	(208)
Operating lease liability	2,111	(861)	(755)
Net cash used in operating activities	(41,886)	(33,075)	(15,301)
Cash flows from investing activities:
Purchases of property and equipment	(1,641)	(192)	(202)
Purchases of available-for-sale investment securities	(42,118)	(126,506)	(21,066)
Maturities of available-for-sale investment securities	90,825	35,082	28,150
Proceeds from sale of property and equipment	179	50	18
Net cash (used in) provided by investing activities	47,245	(91,566)	6,900
Cash flows from financing activities:
Proceeds from issuance of common stock through option exercises	1	62	0
Proceeds from issuance of common stock through employee stock purchase plan	44	11	10
Proceeds from issuance of common stock from at-the-market offerings, net of offering costs	5,472	14,070	6,437
Proceeds from issuance of common stock from committed purchase agreement, net of offering costs	0	15,236	0
Proceeds from issuance of common stock from underwritten follow-on offering, net of offering costs	0	80,646	18,779
Principal paid on finance lease liabilities	(66)	0	0
Repayments on borrowings	0	0	(9,083)
Net cash provided by financing activities	5,451	110,025	16,143
Net change in cash, cash equivalents and restricted cash	10,810	(14,616)	7,742
Cash, cash equivalents and restricted cash at beginning of period	2,336	16,952	9,210
Cash, cash equivalents and restricted cash at end of period	13,146	2,336	16,952
Cash and cash equivalents at the end of period	9,981	2,336	16,952
Restricted cash at the end of period	3,165	0	0
Cash, cash equivalents and restricted cash at the end of period	13,146	2,336	16,952
Supplemental disclosure of cash flow information:
Interest paid	54	0	308
Purchases of property and equipment in accounts payable	1,194	0	17
Right-of-use assets obtained in exchange for lease obligation	$ 8,695	$ 0	$ 0

Organization, Business and Basi

Organization, Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Organization, Business and Basis of Presentation	1. Organization, Business and Basis of Presentation Organization and Business We were incorporated in the state of Delaware on September 8, 2005. We are focused on the discovery and development of first-in-class medicines from our proprietary tRNA synthetase platform. Principles of Consolidation Our consolidated financial statements include our accounts and our 98 % majority-owned subsidiary in Hong Kong, Pangu BioPharma Limited (Pangu BioPharma). All intercompany transactions and balances are eliminated in consolidation. Liquidity and Financial Condition We have incurred losses and negative cash flows from operations since our inception. As of December 31, 2022, we had an accumulat ed deficit of $ 417.6 million and we expect to continue to incur net losses for the foreseeable future. As of December 31, 2022, our cash, cash equivalents, available-for-sale investments and restricted cash were $ 69.3 million. Additionally, in February 2023, we completed an underwritten follow-on public offering of 23,125,000 shares of our common stock, including the partial exercise of the underwriters’ option to purchase additional shares, at a price to the public of $ 2.25 per share. The total gross proceeds from the offering were approximately $ 52.0 million, before deducting underwriting discounts, commissions and offering expenses payable by us. We also received a $ 10.0 million milestone payment from the Kyorin Agreement in February 2023. We believe that our current cash, cash equivalents, available-for-sale investments and restricted cash, will be sufficient to meet our anticipated cash requirements for a period of at least one year from the date of this Annual Report. We do not expect to generate any revenues from product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our product candidates, which we expect will take a number of years at a minimum. If we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Accordingly, we will need to raise substantial additional capital to fund our operations. The amount and timing of our future funding requirements will depend on many factors, including the pace and results of our preclinical and clinical development efforts and the timing and nature of the regulatory approval process for our product candidates. We anticipate that we will seek to fund our operations through equity offerings, grant funding, collaborations, strategic partnerships and/or licensing arrangements, and when we are closer to commercialization of our product candidates potentially through debt financings. However, we may be unable to raise additional capital or enter into such arrangements when needed on favorable terms or at all. Our failure to raise capital or enter into such arrangements when needed would have a negative impact on our financial condition and ability to develop our product candidates. Restricted Cash As of December 31, 2022, restricted cash was approximately $ 3.2 million, which was held as a security deposit in conjunction with our new facility lease and financing leases as discussed further in Note 6 - Commitments and Contingencies. Use of Estimates Our consolidated financial statements are prepared in accordance with generally accepted accounting principles (GAAP). The preparation of our consolidated financial statements requires us to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure for these items in our consolidated financial statements and accompanying notes. The most significant estimates in our consolidated financial statements relate to the fair value of equity issuances and awards, and clinical trial and research and development expenses. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ materially from these estimates and assumptions. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. We view our operations and manage our business in one operating segment.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Cash and Cash Equivalents and Restricted Cash Cash and cash equivalents and restricted cash consist primarily of readily available checking, money market accounts and money market funds. We consider all highly liquid investments that mature in three months or less when purchased to be cash equivalents. Investment Securities Investment securities primarily consist of investment grade corporate and municipal bond securities and commercial paper. We classify all investment securities as available-for-sale. Investment securities are carried at fair value, with the unrealized gains and losses, if any, reported as a component of other comprehensive income (loss) in stockholders’ equity until realized. Realized gains and losses from the sale of investment securities, if any, are determined on a specific identification basis. A decline in the market value of any investment security below cost that is determined to be other than temporary will result in an impairment charge to earnings and a new cost basis for the security is established. No such impairment charges were recorded for any period presented. Premiums and discounts are amortized or accreted over the life of the related security as an adjustment to yield using the straight-line method and are included in interest income. Interest income is recognized when earned. As of December 31, 2022, we held an aggregate total of $ 56.2 million of investment securities which consisted of corporate debt securities, municipal bonds and commercial paper all of which will mature in less than two years , and there was an unrealized loss of approximately $ 0.4 million between the amortized cost and fair value of these investment securities. As of December 31, 2021, we held $ 105.6 million of corporate debt securities, municipal bonds and commercial paper, all of which mature in less than one year , and there was an unrealized loss of approximately $ 0.2 million between the amortized cost and fair value of these investment securities. Concentration of Credit Risk Financial instruments that potentially subject us to significant concentration of credit risk consist primarily of cash, cash equivalents, restricted cash and investment securities. We have established guidelines regarding diversification of investments and their maturities, which are designed to maintain principal and maximize liquidity. We maintain deposits in federally insured financial institutions in excess of federally insured limits. We have not experienced any losses in such accounts and we believe that we are not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. Property and Equipment Property and equipment are stated at cost and depreciated on a straight-line basis over the estimated useful life of the related assets (generally three to seven years ). Leasehold improvements are stated at cost and amortized on a straight-line basis over the lesser of the remaining term of the related lease or the estimated useful life of the leasehold improvements. Repairs and maintenance costs are charged to expense as incurred . Impairment of Long-Lived Assets Long-lived assets consist primarily of property and equipment and right-of-use assets (ROU) associated with our operating and financing leases. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. While our current and historical operating losses are indicators of impairment, we believe that future cash flows to be received support the carrying value of our long-lived assets and, accordingly, have no t recognized any impairment losses since inception. Accrued Expenses Accrued expenses include salaries, wages, benefits costs, consulting fees, legal, tenant improvement costs for our new corporate headquarters facility and research and development costs. We have entered into contractual arrangements related to our clinical studies with clinical research organizations (CROs) and contracted development and manufacturing organizations (CDMOs) and recognize expense based on work completed and efforts expended pursuant to our contractual arrangements. We make estimates of our accrued CRO costs as of each balance sheet date based on facts and circumstances known at the time and include total trial management costs, sites activated, patients enrolled and number of patient visits. We estimate the time period over which services will be performed and the level of effort to be expended in each period. There may be instances in which payments made to our service providers including CROs and CDMOs, will temporarily exceed the level of services provided and result in a prepayment of the expense. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual or prepaid expense balance accordingly. Historically, our estimated accrued liabilities have materially approximated actual expenses incurred. Leases We determine if an arrangement is a lease at inception. Short-term leases with an initial term of 12 months or less are not recorded on our balance sheet. For long-term leases with an initial term of greater than 12 months, we recognize a right-of-use asset (ROU) and a lease liability based on the present value of future lease payments using an estimated rate of interest that we would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. We determine the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. Rent expense for operating leases is recognized on a straight-line basis over the lease term and is included in operating expenses in our consolidated statements of operations. For financing leases, interest expense and amortization of the ROU is included in operating expenses in our consolidated statements of operations and variable lease payments are recorded as incurred. If a lease is modified, the modified contract is evaluated to determine whether it is or contains a lease. If a lease continues to exist, the lease modification is determined to be a separate contract when the modification grants the lessee an additional ROU that is not included in the original lease and the lease payments increase commensurate with the standalone price for the additional ROU. A lease modification that results in a separate contract will be accounted for in the same manner as a new lease. For a modification that is not a separate contract, we reassess the lease classification using the modified terms and conditions and the facts and circumstances as of the effective date of the modification and recognize the amount of the remeasurement of the lease liability for the modified lease as an adjustment to the corresponding lease ROU asset. Our ROU assets consist of non-cancelable operating lease and financing leases. Non-cancelable operating leases include our existing office and laboratory space and new corporate headquarters. Financing leases include various research and development and information technology equipment. We do not separate lease and non-lease components for our long-term leases. Revenue Recognition We evaluate our agreements under ASC Topic 606, Revenue from Contracts with Customers and ASC Topic 808, Collaborative Arrangements . We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under our agreement, we perform the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) we satisfy each performance obligation. As part of the accounting for these arrangements, we must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. We use key assumptions to determine the stand-alone selling price, which may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success. We recognize revenue in one of two ways, over time or at a point in time. We recognize revenue over time when we are executing on our performance obligation over time and our partner receives benefit over time. For example, we recognize revenue over time when we provide research and development services. We recognize revenue at a point in time when we transfer control of a distinct performance obligation to our partner. For example, if a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. Research and Development Costs Research and development costs are expensed as incurred. Research and development costs include: salaries and employee-related expenses, including stock-based compensation and benefits for personnel in research and product development functions; costs associated with conducting our preclinical, development and regulatory activities, including fees paid to third-party professional consultants, service providers and our scientific, therapeutic and clinical advisors; costs to acquire, develop and manufacture preclinical study and clinical trial materials; costs incurred under clinical trial agreements with clinical research organizations and investigative sites; costs for laboratory supplies; payments related to licensed products and technologies; allocated facilities and information technology costs; and depreciation. Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain. Stock-Based Compensation We evaluate our stock-based compensation arrangements under ASC Topic 718, Compensation – Stock Compensation. Stock-based compensation expense represents the grant date fair value of employee stock option and restricted stock unit grants recognized as expense over the requisite service period of the awards (usually the vesting period) on a straight-line basis. We estimate fair value of stock option grants using the Black-Scholes option pricing model. We estimate the fair value using assumptions, including the risk-free interest rate, the expected volatility of a peer group of similar companies, the expected term of the awards and the expected dividend yield. These estimates involve inherent uncertainties and the application of management’s judgment. If factors change and different assumptions are used, our stock-based compensation expense could be materially different in the future. Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized as income in the period that includes the enactment date. We recognize net deferred tax assets to the extent that we believe these assets are more likely than not to be realized. In making such a determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations. If we determine that we would be able to realize the deferred tax assets in the future in excess of their net recorded amount, we would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. We record uncertain tax positions on the basis of a two-step process whereby (1) we determine whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, we recognize the largest amount of tax benefit that is more than 50 % likely to be realized upon ultimate settlement with the related tax authority. We recognize interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted 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 common stock and common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of convertible preferred stock, warrants for common stock, options and restricted stock units outstanding under our stock option plans and inducement grants and estimated shares to be purchased under our employee stock purchase plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common share equivalents): Years Ended December 31, 2022 2021 2020 Common stock warrants 13,760 13,760 13,904 Common stock options and restricted stock units 3,077,608 1,420,050 584,211 Employee stock purchase plan 34,588 2,045 1,602 Total 3,125,956 1,435,855 599,717 The following table summarizes our net loss per share (in thousands, except per share data): Years Ended December 31, 2022 2021 2020 Numerator: Net loss attributable to aTyr Pharma, Inc. $ ( 45,338 ) $ ( 33,768 ) $ ( 16,224 ) Denominator: Weighted average common shares outstanding 28,419,569 19,080,878 9,160,269 Weighted average common shares subject to repurchase — — — Shares used in computing net loss per share, basic and diluted 28,419,569 19,080,878 9,160,269 Net loss per share - basic and diluted $ ( 1.60 ) $ ( 1.77 ) $ ( 1.77 ) Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses (Topic 326), to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in Topic 326 replace the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Topic 326 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years for smaller reporting companies. We do not expect the adoption of the amendments in Topic 326 to have a material effect on our consolidated financial position or results of operations when such amendment is effective.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The carrying amounts of cash equivalents, prepaid and other assets, accounts payable and accrued liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. Investment securities are recorded at fair value. The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Financial assets measured at fair value on a recurring basis consist of investment securities. Investment securities are recorded at fair value, defined as the exit price in the principal market in which we would transact, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Level 2 securities are valued using quoted market prices for similar instruments, non-binding market prices that are corroborated by observable market data, or discounted cash flow techniques and include our investments in asset-backed securities, commercial paper, corporate debt securities and municipal bonds. We have no financial liabilities measured at fair value on a recurring basis. None of our non-financial assets and liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented. Assets measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements Using Total Quoted Prices in Markets Identical Significant Significant As of December 31, 2022 Assets: Current: Cash equivalents $ 8,585 $ 8,585 $ — $ — Available-for-sale investments: Commercial paper 28,074 — 28,074 — Corporate debt securities 26,094 — 26,094 — Municipal bonds 1,997 — 1,997 — Total available-for-sale investments 56,165 — 56,165 — Total assets measured at fair value $ 64,750 $ 8,585 $ 56,165 $ — Fair Value Measurements Using Total Quoted Prices in Markets Identical Significant Significant As of December 31, 2021 Assets: Current: Cash equivalents $ 2,052 $ 2,052 $ — $ — Available-for-sale investments: Commercial paper 36,921 — 36,921 — Corporate debt securities 55,713 — 55,713 — Municipal bonds 12,941 — 12,941 — Total available-for-sale investments 105,575 — 105,575 — Total assets measured at fair value $ 107,627 $ 2,052 $ 105,575 $ — As of December 31, 2022 and 2021, available-for-sale investments are detailed as follows (in thousands): December 31, 2022 Contractual Maturity Gross Gross Gross Market Value Available-for-sale investments: Commercial paper Within 1 year $ 28,121 $ — $ ( 47 ) $ 28,074 Corporate debt securities 1 to 2 years 26,401 — ( 307 ) 26,094 Municipal bonds Within 1 year 2,026 — ( 29 ) 1,997 $ 56,548 $ — $ ( 383 ) $ 56,165 December 31, 2021 Contractual Maturity Gross Gross Gross Market Value Available-for-sale investments: Commercial paper Within 1 year $ 36,956 $ — $ ( 35 ) $ 36,921 Corporate debt securities 1 to 2 years 55,859 — ( 146 ) 55,713 Municipal bonds 1 to 2 years 12,973 — ( 32 ) 12,941 $ 105,788 $ — $ ( 213 ) $ 105,575 At each reporting date, we perform an evaluation of impairment to determine if the unrealized losses are other-than-temporary. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition of the issuer, and our intent and ability to hold the investment until recovery of its amortized cost basis. Based on our evaluation, we determined that the unrealized losses were not other-than-temporary as of December 31, 2022. As of December 31, 2022, 20 out of 25 available-for-sale investments, were in a gross unrealized loss position of which 12 available-for-sale investments with a market value of $ 24.2 million were at such position for greater than 12 months . As of December 31, 2021, all available-for-sale investments were in a gross unrealized loss position and had been in such position for less than twelve months .

License, Collaboration and Othe

License, Collaboration and Other Agreements	12 Months Ended
	Dec. 31, 2022
License Agreement [Abstract]
License, Collaboration and Other Agreements	4. License, Collaboration and Other Agreements Kyorin Pharmaceutical Co., Ltd. In January 2020, we entered into a collaboration and license agreement (Kyorin Agreement) with Kyorin Pharmaceutical Co., Ltd. (Kyorin) for the development and commercialization of efzofitimod for the treatment of interstitial lung disease ( ILD) in Japan. Under the Kyorin Agreement, Kyorin received an exclusive right to develop and commercialize efzofitimod in Japan for all forms of ILD, and is obligated to fund all research, development, regulatory, marketing and commercialization activities in Japan. In September 2020, Kyorin began dosing patients in a Phase 1 clinical trial of efzofitimod (known as KRP-R120 in Japan) and completed the last subject visit in December 2020. The Phase 1 clinical trial, which was conducted and funded by Kyorin, was a placebo-controlled clinical trial to evaluate the safety, pharmacokinetics (PK) and immunogenicity of efzofitimod in 32 healthy Japanese male volunteers. Efzofitimod was observed to be generally well-tolerated with no drug-related serious adverse events, and PK findings were consistent with previous studies of efzofitimod. Kyorin is also participating in the EFZO-FIT study as the local sponsor in Japan. In February 2023, Kyorin dosed the first patient in Japan in the EFZO-FIT study which triggered a $ 10.0 million milestone payment to us. To date, the Kyorin Agreement has generated $ 20.0 million in upfront and milestone payments to us and we are eligible to receive up to an additional $ 155.0 million in the aggregate upon achievement of certain development, regulatory and sales milestones, as well as tiered royalties on any net sales in Japan. Either party may terminate the Kyorin Agreement in the event that the other party breaches the agreement and fails to cure the breach, becomes insolvent or challenges certain of the intellectual property rights licensed under the agreement. We assessed our license and collaboration with Kyorin in accordance with Topic 606 and concluded that Kyorin is a customer. We identified the following performance obligations under the Kyorin Agreement: 1) the license of efzofitimod for ILD in Japan; and 2) free clinical trial material for Kyorin’s Phase 1 clinical trial. Kyorin is participating in the EFZO-FIT study and received approval from the Pharmaceuticals and Medical Devices Agency (PMDA) to commence the EFZO-FIT study in Japan during the year ended December 31, 2022. As of December 31, 2022, Kyorin had scheduled site visits for patient screenings which led to the first patient dosing in February 2023. We determined that the development milestone achieved in February 2023 became probable of achievement as of December 31, 2022. Because our performance obligations were already completed, we recorded the $ 10.0 million collaboration revenue and a receivable from Kyorin as of December 31, 2022. We also recorded an additional $ 0.4 million in collaboration revenue from Kyorin during the year ended December 31, 2022 for drug product material sold to Kyorin for the Japan portion of the EFZO-FIT study. The remaining milestones and royalty payments under the Kyorin Agreement are variable consideration. Since the milestone payments are binary in nature, we will use the “most-likely” method to evaluate whether the milestones should be included as revenue. We will constrain these amounts until the milestone is probable of being achieved. The royalties are dependent on future sales by Kyorin which are at the full discretion of Kyorin. Accordingly, we will apply a constraint to these amounts until the future sale sales have occurred.

Balance Sheet Details

Balance Sheet Details	12 Months Ended
	Dec. 31, 2022
Balance Sheet Details [Abstract]
Balance Sheet Details	5. Balance Sheet Details Prepaid expenses consist of the following (in thousands): December 31, 2022 2021 Prepaid clinical and research expense $ 334 $ 557 Prepaid manufacturing expenses 2,049 4,188 Other prepaid expenses 567 478 $ 2,950 $ 5,223 Property and equipment consist of the following (in thousands): December 31, 2022 2021 Computer and office equipment $ 620 $ 616 Scientific and laboratory equipment 4,379 4,383 Tenant improvements 4,414 1,701 9,413 6,700 Less accumulated depreciation and amortization ( 6,354 ) ( 6,157 ) $ 3,059 $ 543 As of December 31, 2022, 2021 and 2020, depreciation expense was $ 0.2 million, $ 0.5 million and $ 0.6 million, respectively. Accrued expenses consist of the following (in thousands): December 31, 2022 2021 Accrued salaries, wages and benefits $ 2,781 $ 2,326 Accrued clinical and manufacturing 5,151 $ 1,004 Other accrued expenses 1,930 672 $ 9,862 $ 4,002

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Operating Leases Existing Corporate Headquarters Facility Lease We have a non-cancelable facility lease that is subject to base lease payments, which escalate over the term of the lease, additional charges for common area maintenance and other costs. In July 2018, we entered into a lease amendment that reduced the space we lease from 24,494 square feet to 20,508 square feet and extended the lease term to May 2023 . With the lease amendment, we do not have an option to extend the lease. New Corporate Headquarters Facility Lease In May 2022, we entered into a lease (the Lease) with San Diego Creekside, LLC (Landlord), as lessor, pursuant to which we agreed to lease from Landlord approximately 23,696 rentable square feet (subject to increase pursuant to the terms of the Lease) of office and laboratory space. The term of the lease (the Lease Term) will commence upon the earlier of April 1, 2023 or the completion of certain leasehold improvements to the Premises (as defined in the Lease), but not sooner than March 1, 2023 (the Lease Commencement Date) and continue for 124 months from the Lease Commencement Date. We also have one option to extend the Lease Term for five years . Base rent during such extension period would be at the fair market rent for the Premises. Under the terms of the Lease, the base rent during the first 12 months of the Lease Term will be $ 5.75 per square foot of rentable area per month, subject to certain upward adjustments of approximately 3.0 % annually. We are entitled to an allowance of $ 5.5 million for tenant improvements, including an option to utilize an additional allowance of up to $ 0.6 million, which, if used by us, would be repaid by us as additional monthly base rent, amortized at 8.0 % per annum during the Lease Term. We provided a $ 0.7 million security deposit in the form of a letter of credit which is included in restricted cash as of December 31, 2022. Future minimum payments under the non-cancelable operating leases and reconciliation to the operating lease liability as of December 31, 2022 were as follows (in thousands): Operating Leases 2023 $ 1,363 2024 1,961 2025 1,895 2026 1,777 2027 1,831 2028 and thereafter 11,102 Less: Amount representing interest ( 6,911 ) Present value of lease payments 13,018 Less: Current portion of operating lease liability ( 630 ) Less: Tenant improvement allowance not yet received ( 2,755 ) Long-term operating lease liability, net of current portion $ 9,633 Operating lease expense was $ 1.5 million, $ 1.0 million and $ 1.0 million for the years ended December 31, 2022, 2021 and 2020, respectively. As of December 31, 2022 and 2021, the weighted average remaining lease term was 9.9 years and 1.4 years, respectively. As of December 31, 2022 and 2021, the weighted average discount rate was 8.8 % and 9.6 %, respectively. Financing Leases In April 2022, we entered into a master financing lease agreement to lease various research and development and information technology equipment over a 48-month term. Future minimum payments under the non-cancelable financing lease and reconciliation to the financing lease liability as of December 31, 2022 were as follows (in thousands): Financing Leases 2023 $ 352 2024 352 2025 352 2026 395 2027 33 Less: Amount representing interest ( 213 ) Present value of lease payments 1,271 Less: Current portion of financing lease liability ( 264 ) Long-term financing lease liability, net of current portion $ 1,007 As of December 31, 2022, the weighted-average remaining lease term was 3.7 years and the weighted-average discount rate was 7.9 %. We provided a $ 2.4 million deposit to be held as collateral for the leased equipment, and this deposit is included in restricted cash as of December 31, 2022.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Underwritten Follow-On Public Offerings In February 2023, we completed an underwritten follow-on public offering of 23,125,000 shares of our common stock, including the partial exercise of the underwriters’ option to purchase additional shares, at a price to the public of $ 2.25 per share. The total gross proceeds from the offering were approximately $ 52.0 m illion, before deducting underwriting discounts, commissions and offering expenses payable by us. In September 2021, we completed an underwritten follow-on public offering of 10,781,250 shares of our common stock, including the full exercise of the underwriters’ option to purchase additional shares, at a price to the public of $ 8.00 per share. The total net proceeds from the offering were approximately $ 80.6 million, after deducting underwriting discounts, commissions and offering expenses payable by us. At-the-Market Offering Programs In April 2022, we entered into an Open Market Sale Agreement SM with Jefferies LLC (Jefferies) implementing an “at-the-market” offering program (the Jefferies ATM Offering Program), pursuant to which we may offer and sell, from time to time and at our option, up to an aggregate of $ 65.0 million of shares of our common stock through Jefferies, acting as sales agent. Jefferies is entitled to a fixed commission rate of up to 3.0 % of the gross sales proceeds of shares sold under the Jefferies ATM Offering Program. During the year ended December 31, 2022, we sold an aggregate of 1,421,627 shares of common stock at a weighted-average price of $ 3.09 per share for net proceeds of approximately $ 4.0 million under the Jefferies ATM Offering Program In March 2021, we entered into a Capital on Demand TM Sales Agreement with JonesTrading Institutional Services LLC (JonesTrading) for an at-the-market offering program (the JonesTrading ATM Offering Program), pursuant to which we were entitled to sell from time to time, at our option, up to an aggregate of $ 25.0 million of shares of our common stock through JonesTrading, as sales agent or principal. JonesTrading was entitled to a commission at a fixed rate of up to 3.0 % of the gross proceeds. During 2021, we sold an aggregate of 986,267 shares of common stock at a weighted-average price of $ 4.75 per share for net proceeds of $ 4.4 million under the JonesTrading ATM Offering Program. In April 2022, we terminated the JonesTrading ATM Offering Program. During 2022 and prior to termination in April 2022, we sold an aggregate of 260,455 shares of common stock at a weighted-average price of $ 6.07 per share for net proceeds of approximately $ 1.5 million under the JonesTrading ATM Offering Program. In May 2019, we entered into a sales agreement with H.C. Wainwright & Co., LLC (Wainwright) for an ATM Offering Program (the Wainwright ATM Offering Program) under which we could offer and sell shares of our common stock having an aggregate offering price of up to $ 10.0 million. In November 2020, we amended our sales agreement with Wainwright to increase the amount of the ATM Offering Program to $ 20.0 million. Wainwright was entitled to a commission at a fixed commission rate equal to 3 % of the gross proceeds. In March 2021, the ATM Offering Program with Wainwright automatically terminated upon the issuance and sale of all of the shares having an aggregate offering price of $ 20.0 million. Under the Wainwright ATM Offering Program, during 2020, we sold an aggregate of 1,657,075 shares of common stock at an average price of $ 4.07 per share for net proceeds of $ 6.4 million. Prior to the termination of the sales agreement with Wainwright, in 2021, we sold an aggregate of 1,988,254 shares of common stock at an average price of $ 4.99 per share for net proceeds of $ 9.6 million. Purchase Agreement In September 2020 , we entered into a common stock purchase agreement (the Purchase Agreement) with Aspire Capital Fund, LLC (Aspire Capital), which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $ 20.0 million of shares of our common stock at our request from time to time during the 30 month term of the Purchase Agreement. Concurrently with entering into the Purchase Agreement , we also entered into a registration rights agreement with Aspire Capital, in which we agreed to file one or more registration statements, as permissible and necessary to register under the Securities Act of 1933, as amended, for the resale of the shares of our common stock that have been and may be issued to Aspire Capital under the Purchase Agreement. In 2021, we sold an aggregate of 3,000,000 shares of common stock at a weighted-avera ge price of $ 5.09 per share for net proceeds of $ 15.2 million under the Purchase Agreement. There were no issuances or sales under the Purchase Agreement during the year ended December 31, 2022, and this agreement has terminated effective March 11, 2023. 2014 Stock Plan We adopted a stock option plan in 2007 (the 2007 Plan), which was subsequently amended, restated and renamed in July 2014 (the 2014 Plan) to provide for the incentive stock options, nonstatutory stock options, stock and rights to purchase restricted stock to eligible recipients. Recipients of incentive stock options are eligible to purchase shares of our common stock at an exercise price equal to no less than the estimated fair market value of such stock on the date of grant. The maximum term of options under the 2014 Plan is ten years . Options granted generally vest over four years . We ceased granting under the 2014 Plan after our IPO in May 2015. Shares underlying any awards under the 2014 Plan that are forfeited, canceled, reacquired by us prior to vesting, satisfied without the issuance of stock or otherwise terminated (other than by exercise) will be added to shares available for issuance under the 2015 Plan. 2015 Stock Plan In April 2015, our board of directors adopted, and our stockholders approved, the 2015 Stock Plan (the 2015 Plan) which became effective on May 6, 2015 . Awards granted under the 2014 Plan prior to our IPO that are forfeited, canceled, reacquired by us prior to vesting satisfied without the issuance of stock or otherwise terminated (other than by exercise) will be added to shares available for issuance under the 2015 Plan. Total shares available for issuance under the 2015 Plan as of December 31, 2022 were 962,179 . Shares underlying any awards under the 2015 Plan that are forfeited, canceled, reacquired by us prior to vesting, satisfied without the issuance of stock or otherwise terminated (other than by exercise) will be added to shares available for issuance under the 2015 Plan. The maximum term of options granted under 2015 Plan is ten years . For an initial grant to an employee, 25 % of the options generally vest on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years. For subsequent grants to an employee, the options generally vest monthly over a four-year term. Inducement Plan In March 2022, our board of directors approved and adopted our 2022 Inducement Plan (our Inducement Plan). Awards granted under our Inducement Plan are in accordance with Nasdaq Listing Rule 5635(c)(4). A total of 300,000 shares of our common stock were initially reserved for the issuance under our Inducement Plan. The maximum term of options granted under our Inducement Plan is ten years . Each option vests over a period of four years , with 25 % of the shares vesting on the one-year anniversary of the applicable vesting commencement date and the remaining 75 % vesting in equal monthly installments over three years , thereafter, subject to continuous employment. During year ended December 31, 2022, we granted nonstatutory stock options under our Inducement Plan to purchase an aggregate of 205,600 shares of our common stock, with a weighted-average exercise price of $ 3.94 per share as inducement awards to new employees. Employee Stock Purchase Plan In April 2015, our board of directors adopted, and our stockholders approved, our 2015 Employee Stock Purchase Plan (the 2015 ESPP) which became effective on May 6, 2015 . As of December 31, 2022, total shares reserved for issuance under the 2015 ESPP were 801,321 . Stock-based Compensation Stock Options Stock option activity is summarized as follows: Number of Weighted- Weighted Aggregate Outstanding as of December 31, 2021 1,412,550 $ 12.01 Granted 1,590,844 $ 3.43 Exercises ( 259 ) $ 3.77 Canceled/forfeited/expired ( 46,965 ) $ 8.59 Outstanding as of December 31, 2022 2,956,170 $ 7.45 8.47 $ — The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows: Years Ended December 31, 2022 2021 2020 Expected term (in years) 5.98 – 6.08 5.50 – 6.08 5.50 – 6.08 Risk-free interest rate 1.7 % – 4.2 % 0.6 % – 1.3 % 0.3 % – 1.5 % Expected volatility 84.2 % – 86.5 % 86.3 % – 104.8 % 102.2 % – 109.7 % Expected dividend yield 0.0 % 0.0 % 0.0 % The assumptions used in the Black-Scholes option pricing model to determine the fair value of the ESPP offering were as follows: Years Ended December 31, 2022 2021 2020 Expected term (in years) 0.50 0.50 0.50 Risk-free interest rate 0.06 % – 4.54 % 0.04 % – 0.12 % 0.1 % – 1.6 % Expected volatility 51.9 % – 95.9 % 89.7 % – 108.12 % 89.7 % – 143.2 % Expected dividend yield 0.0 % 0.0 % 0.0 % Expected term . The expected term represents the period of time that options are expected to be outstanding. Because we do not have sufficient history of exercise behavior, we determine the expected life assumption using the simplified method, which is an average of the contractual term of the option and its vesting period. Risk-free interest rate. We base the risk-free interest rate assumption on the U.S. Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued. Expected volatility. The expected volatility assumption is based on our historical volatility as well as the volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology industry. Expected dividend yield. We base the expected dividend yield assumption on the fact that we have never paid cash dividends and have no present intention to pay cash dividends. Restricted Stock Units Occasionally, we grant restricted stock units to employees. The fair value of restricted stock is determined by the closing price of the our common stock reported on the Nasdaq Capital Market on the date of grant. Restricted stock unit activity is summarized as follows: Number of Outstanding Weighted-Average Balance as of December 31, 2021 7,500 $ 4.08 Granted 116,438 $ 5.13 Released ( 2,500 ) $ 4.13 Balance as of December 31, 2022 121,438 $ 5.09 The allocation of stock-based compensation for all options, including performance options with market condition and restricted stock units is as follows (in thousands): Years Ended December 31, 2022 2021 2020 Research and development $ 528 $ 295 $ 254 General and administrative 1,626 1,319 1,211 Total stock-based compensation expense $ 2,154 $ 1,614 $ 1,465 The weighted-average grant date fair value per share of stock options granted by us, during the years ended December 31, 2022, 2021 and 2020 was $ 2.49 , $ 3.82 and $ 3.39 , respectively. The total grant date fair value of restricted stock units granted by us during the years ended December 31, 2022, 2021, and 2020 was approximately $ 597,000 , $ 16,000 and $ 21,000 , respectively. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2022, 2021 and 2020 was approximately $ 1,000 , $ 80,000 and $ 0 , respectively. The aggregate intrinsic value of restricted stock units released during the years ended December 31, 2022, 2021 and 2020 was approximately $ 6,000 , $ 31,000 and $ 34,000 , respectively. As of December 31, 2022, total unrecognized share-based compensation expense related to unvested stock options and restricted stock units was approximately $ 5.5 million and $ 0.4 million, respectively. As of December 31, 2022, these unrecognized costs for options and restricted stock units are expected to be recognized ratably over a weighted-average period of approximately 3.0 years and 2.2 years, respectively. Warrants Warrants outstanding for the purchase of common stock as of December 31, 2022 were as follows: Number Exercise Price Expiration Outstanding Per Share Date 1,066 $ 281.50 July 2023 6,830 $ 43.93 November 2023 2,978 $ 50.37 June 2024 2,886 $ 51.98 December 2024 13,760 Common Stock Reserved for Future Issuance Common stock reserved for future issuance was as follows: December 31, 2022 Common stock warrants 13,760 Common stock options and restricted stock units 3,077,608 Shares available under the 2015 equity incentive plan 962,179 Shares available under the 2022 inducement plan 98,400 Shares available under the employee stock purchase plan 801,321 4,953,268

Income Tax

Income Tax	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Tax	8. Income Tax Pretax losses were generated by both domestic and foreign operations as follows (in thousands): Years Ended December 31, 2022 2021 2020 United States $ ( 45,086 ) $ ( 33,316 ) $ ( 15,950 ) Foreign ( 254 ) ( 458 ) ( 280 ) Worldwide pre-tax loss $ ( 45,340 ) $ ( 33,774 ) $ ( 16,230 ) For the years ended December 31, 2022, 2021, and 2020, we did no t record a provision for income taxes due to a full valuation allowance against our deferred taxes. A reconciliation of the expected statutory federal income tax provision to the actual income tax provision is summarized as follows (in thousands): Years Ended December 31, 2022 2021 2020 Expected income taxes benefit at federal statutory rate $ ( 9,521 ) $ ( 7,093 ) $ ( 3,408 ) State income taxes, net of federal benefit ( 380 ) ( 2,313 ) ( 12 ) Permanent items and other 438 592 169 Stock compensation 44 90 804 Research credits ( 4,415 ) ( 1,253 ) ( 835 ) Unrecognized tax benefits 2,454 500 334 Foreign rate differential 11 21 13 Change in tax rate 34 52 ( 7 ) Change in valuation allowance 11,335 9,404 2,942 Income tax (benefit) expense $ — $ — $ — Deferred income taxes are provided for temporary differences in recognizing certain income and expense items for financial and tax reporting purposes. The deferred tax assets consisted primarily of the income tax benefits from net operating loss (NOL) carryforwards, research and development credits and capitalized research and development expenses, along with other accruals and reserves. Valuation allowances of $ 95.5 million and $ 84.1 million as of December 31, 2022 and 2021, respectively, have been recorded to offset deferred tax assets as realization of such assets does not meet the more-likely-than-not threshold under ASC 740, Accounting for Income Taxes . Significant components of our deferred tax assets are summarized as follows (in thousands): December 31, 2022 2021 Deferred tax assets: Net operating loss carryforwards $ 52,752 $ 48,833 Capitalized research and development expenses 22,576 18,086 Research credits and other state credits 16,021 13,695 Intangible assets 1,278 1,465 Reserve and accruals 596 641 Share-based compensation expense 1,628 1,369 Lease liability 2,157 290 Total tax assets 97,008 84,379 Valuation allowance ( 95,484 ) ( 84,112 ) Total deferred tax assets $ 1,524 $ 267 Deferred tax liabilities: Right of use lease assets ( 1,524 ) ( 267 ) Total deferred tax liabilities ( 1,524 ) ( 267 ) Net deferred tax assets $ — $ — The Tax Cuts and Jobs Act of 2017 requires taxpayers to capitalize and amortize research and development (R&D) expenditures under section 174 for tax years beginning after December 31, 2021. This rule became effective at the beginning of 2022 which resulted in a capitalization of R&D costs of approximately $ 41.0 million. We will amortize these costs for tax purposes over 5 years if the R&D was performed in the U.S. and over 15 years if the R&D was performed outside the U.S. As of December 31, 2022, we had federal NOL carryforwards of approximately $ 221.0 million, with $ 108.5 million of NOLs generated after December 31, 2017 carrying forward indefinitely and $ 112.5 million of NOLs that will begin to expire in 2025 . NOL carryforwards generated after January 1, 2018 are subject to an 80% of taxable income limitation in accordance with the Tax Cuts and Jobs Act of 2017. We had state net operating loss carryforwards of approximately $ 194.4 million, and foreign net operating loss carryforwards of $ 9.0 million. The state net operating losses began to expire in 2022 . The foreign net operating losses carry over indefinitely. As of December 31, 2022, we had federal and state research and development credit carryforwards of approximately $ 8.3 million and $ 5.2 million, respectively, which begin to expire in 2026 for both federal and state purposes. We had $ 15.4 million of federal Orphan Drug Credits as of December 31, 2022, which will begin to expire in 2035 . Utilization of the domestic NOL and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that may have occurred or that could occur in the future, as required by Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the Code), as well as similar state and foreign provisions. These ownership changes may limit the amount of NOL and research and development credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders. Since the Company’s formation, we raised capital through the issuance of capital stock on several occasions which on its own or combined with the purchasing stockholders’ subsequent disposition of those shares, has resulted in such an ownership change, and could result in an ownership change in the future. Upon the occurrence of an ownership change under Section 382 as outlined above, utilization of the NOL and research and development credit carryforwards become subject to an annual limitation under Section 382 of the Code, which is determined by first multiplying the value of our stock at the time of the ownership change by the applicable long-term, tax-exempt rate, which could be subject to additional adjustments. Any limitation may result in expiration of a portion of our NOL or research and development credit carryforwards before utilization. Due to the existence of the valuation allowance, any impact to the NOL and research and development tax credit carryforwards from Section 382 analysis will be offset by a corresponding adjustment to valuation allowance, resulting in no tax provision impact. We recognize a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more-likely-than-not recognition threshold to be recognized. Our practice is to recognize interest and penalties related to income tax matters in income tax expense. We had no accrual for interest and penalties on our balance sheet and had not recognized interest or penalties in the consolidated statements of operations for the years ended December 31, 2022, 2021 and 2020. Due to the existence of the valuation allowance, future changes in unrecognized tax benefits will not impact our effective tax rate. Uncertain tax positions are evaluated based upon the facts and circumstances that exist at each reporting period. Subsequent changes in judgment based upon new information may lead to changes in recognition, derecognition, and measurement. Adjustments may result, for example, upon resolution of an issue with the taxing authorities, or expiration of a statute of limitations barring an assessment for an issue. The activity related to our unrecognized tax benefits is summarized as follows (in thousands): December 31, 2022 2021 2020 Balance as of beginning of year $ 22,232 $ 21,707 $ 21,302 Increase (decrease) related to prior year tax positions ( 48 ) ( 9 ) 3 Increase related to current year tax positions 2,961 534 402 Balance as of end of year $ 25,145 $ 22,232 $ 21,707 We do no t anticipate that the amount of unrecognized tax benefits as of December 31, 2022 will change within the next twelve months. We are subject to taxation in the United States, Hong Kong and state jurisdictions. Our tax years from inception are subject to examination by the United States, Hong Kong and various state authorities due to carry forward of unutilized NOLs and research and development credits.

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Employee Benefits	9. Employee Benefits 401(k) Plan We maintain a defined contribution 401(k) plan available to eligible employees. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under federal tax regulations. In April 2015 , our Board of Directors approved a policy, beginning on June 1, 2015 , to match employee contributions equal to 50 % of the participant’s contribution of up to a maximum of 6 % of the participant’s annual salary. We made discretionary contributions totaling $ 0.2 million during each of the years ended December 31, 2022, 2021 and 2020.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events Achievement of Development Milestone by Kyorin On February 6, 2023, we announced that our partner Kyorin dosed the first patient in Japan in the EFZO-FIT study. This achievement triggered a $ 10.0 million milestone payment by Kyorin to us pursuant to the Kyorin Agreement and we received the cash payment of $ 10.0 million in February 2023. Kyorin is our partner for the development and commercialization of efzofitimod for ILD in Japan. Under the Kyorin Agreement, we have generated $ 20.0 million in upfront and milestone payments to date and are eligible to receive up to an additional $ 155.0 million in the aggregate upon the achievement of certain development, regulatory and sales milestones, as well as tiered royalties on any net sales in Japan. Kyorin has the exclusive rights to develop and commercialize efzofitimod in Japan for all forms of ILD. Follow-On Public Offering In February 2023, we completed an underwritten follow-on public offering of 23,125,000 shares of our common stock, including the partial exercise of the underwriters’ option to purchase additional shares, at a price to the public of $ 2.25 per share. The tota l gross proceeds from the offering were approximately $ 52.0 m illion, before deducting underwriting discounts, commissions and offering expenses payable by us. Sales of Common Stock through the ATM Offering Program From January 1, 2023 through March 14, 2023, we sold an aggregate of 516,453 shares of common stock at a weighted-average price of $ 2.35 per share through the ATM Offering Program for net proceeds of $ 1.2 million. Silicon Valley Bank Closure On March 10, 2023, we became aware of reports indicating the closure of Silicon Valley Bank (SVB) and the appointment of the Federal Deposit Insurance Corporation as receiver. As of March 10, 2023, we hold less than 2 % of our current cash, cash equivalents, restricted cash and available-for-sale investments with SVB.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Organization and Business	Organization and Business We were incorporated in the state of Delaware on September 8, 2005. We are focused on the discovery and development of first-in-class medicines from our proprietary tRNA synthetase platform.
Principles of Consolidation	Principles of Consolidation Our consolidated financial statements include our accounts and our 98 % majority-owned subsidiary in Hong Kong, Pangu BioPharma Limited (Pangu BioPharma). All intercompany transactions and balances are eliminated in consolidation.
Liquidity and Financial Condition	Liquidity and Financial Condition We have incurred losses and negative cash flows from operations since our inception. As of December 31, 2022, we had an accumulat ed deficit of $ 417.6 million and we expect to continue to incur net losses for the foreseeable future. As of December 31, 2022, our cash, cash equivalents, available-for-sale investments and restricted cash were $ 69.3 million. Additionally, in February 2023, we completed an underwritten follow-on public offering of 23,125,000 shares of our common stock, including the partial exercise of the underwriters’ option to purchase additional shares, at a price to the public of $ 2.25 per share. The total gross proceeds from the offering were approximately $ 52.0 million, before deducting underwriting discounts, commissions and offering expenses payable by us. We also received a $ 10.0 million milestone payment from the Kyorin Agreement in February 2023. We believe that our current cash, cash equivalents, available-for-sale investments and restricted cash, will be sufficient to meet our anticipated cash requirements for a period of at least one year from the date of this Annual Report. We do not expect to generate any revenues from product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our product candidates, which we expect will take a number of years at a minimum. If we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Accordingly, we will need to raise substantial additional capital to fund our operations. The amount and timing of our future funding requirements will depend on many factors, including the pace and results of our preclinical and clinical development efforts and the timing and nature of the regulatory approval process for our product candidates. We anticipate that we will seek to fund our operations through equity offerings, grant funding, collaborations, strategic partnerships and/or licensing arrangements, and when we are closer to commercialization of our product candidates potentially through debt financings. However, we may be unable to raise additional capital or enter into such arrangements when needed on favorable terms or at all. Our failure to raise capital or enter into such arrangements when needed would have a negative impact on our financial condition and ability to develop our product candidates.
Restricted Cash	Restricted Cash As of December 31, 2022, restricted cash was approximately $ 3.2 million, which was held as a security deposit in conjunction with our new facility lease and financing leases as discussed further in Note 6 - Commitments and Contingencies.
Use of Estimates	Use of Estimates Our consolidated financial statements are prepared in accordance with generally accepted accounting principles (GAAP). The preparation of our consolidated financial statements requires us to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure for these items in our consolidated financial statements and accompanying notes. The most significant estimates in our consolidated financial statements relate to the fair value of equity issuances and awards, and clinical trial and research and development expenses. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ materially from these estimates and assumptions.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. We view our operations and manage our business in one operating segment.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted Cash Cash and cash equivalents and restricted cash consist primarily of readily available checking, money market accounts and money market funds. We consider all highly liquid investments that mature in three months or less when purchased to be cash equivalents.
Investment Securities	Investment Securities Investment securities primarily consist of investment grade corporate and municipal bond securities and commercial paper. We classify all investment securities as available-for-sale. Investment securities are carried at fair value, with the unrealized gains and losses, if any, reported as a component of other comprehensive income (loss) in stockholders’ equity until realized. Realized gains and losses from the sale of investment securities, if any, are determined on a specific identification basis. A decline in the market value of any investment security below cost that is determined to be other than temporary will result in an impairment charge to earnings and a new cost basis for the security is established. No such impairment charges were recorded for any period presented. Premiums and discounts are amortized or accreted over the life of the related security as an adjustment to yield using the straight-line method and are included in interest income. Interest income is recognized when earned. As of December 31, 2022, we held an aggregate total of $ 56.2 million of investment securities which consisted of corporate debt securities, municipal bonds and commercial paper all of which will mature in less than two years , and there was an unrealized loss of approximately $ 0.4 million between the amortized cost and fair value of these investment securities. As of December 31, 2021, we held $ 105.6 million of corporate debt securities, municipal bonds and commercial paper, all of which mature in less than one year , and there was an unrealized loss of approximately $ 0.2 million between the amortized cost and fair value of these investment securities.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject us to significant concentration of credit risk consist primarily of cash, cash equivalents, restricted cash and investment securities. We have established guidelines regarding diversification of investments and their maturities, which are designed to maintain principal and maximize liquidity. We maintain deposits in federally insured financial institutions in excess of federally insured limits. We have not experienced any losses in such accounts and we believe that we are not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.
Property and Equipment	Property and Equipment Property and equipment are stated at cost and depreciated on a straight-line basis over the estimated useful life of the related assets (generally three to seven years ). Leasehold improvements are stated at cost and amortized on a straight-line basis over the lesser of the remaining term of the related lease or the estimated useful life of the leasehold improvements. Repairs and maintenance costs are charged to expense as incurred .
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist primarily of property and equipment and right-of-use assets (ROU) associated with our operating and financing leases. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. While our current and historical operating losses are indicators of impairment, we believe that future cash flows to be received support the carrying value of our long-lived assets and, accordingly, have no t recognized any impairment losses since inception.
Accrued Expenses	Accrued Expenses Accrued expenses include salaries, wages, benefits costs, consulting fees, legal, tenant improvement costs for our new corporate headquarters facility and research and development costs. We have entered into contractual arrangements related to our clinical studies with clinical research organizations (CROs) and contracted development and manufacturing organizations (CDMOs) and recognize expense based on work completed and efforts expended pursuant to our contractual arrangements. We make estimates of our accrued CRO costs as of each balance sheet date based on facts and circumstances known at the time and include total trial management costs, sites activated, patients enrolled and number of patient visits. We estimate the time period over which services will be performed and the level of effort to be expended in each period. There may be instances in which payments made to our service providers including CROs and CDMOs, will temporarily exceed the level of services provided and result in a prepayment of the expense. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual or prepaid expense balance accordingly. Historically, our estimated accrued liabilities have materially approximated actual expenses incurred.
Leases	Leases We determine if an arrangement is a lease at inception. Short-term leases with an initial term of 12 months or less are not recorded on our balance sheet. For long-term leases with an initial term of greater than 12 months, we recognize a right-of-use asset (ROU) and a lease liability based on the present value of future lease payments using an estimated rate of interest that we would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. We determine the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. Rent expense for operating leases is recognized on a straight-line basis over the lease term and is included in operating expenses in our consolidated statements of operations. For financing leases, interest expense and amortization of the ROU is included in operating expenses in our consolidated statements of operations and variable lease payments are recorded as incurred. If a lease is modified, the modified contract is evaluated to determine whether it is or contains a lease. If a lease continues to exist, the lease modification is determined to be a separate contract when the modification grants the lessee an additional ROU that is not included in the original lease and the lease payments increase commensurate with the standalone price for the additional ROU. A lease modification that results in a separate contract will be accounted for in the same manner as a new lease. For a modification that is not a separate contract, we reassess the lease classification using the modified terms and conditions and the facts and circumstances as of the effective date of the modification and recognize the amount of the remeasurement of the lease liability for the modified lease as an adjustment to the corresponding lease ROU asset. Our ROU assets consist of non-cancelable operating lease and financing leases. Non-cancelable operating leases include our existing office and laboratory space and new corporate headquarters. Financing leases include various research and development and information technology equipment. We do not separate lease and non-lease components for our long-term leases.
Revenue Recognition	Revenue Recognition We evaluate our agreements under ASC Topic 606, Revenue from Contracts with Customers and ASC Topic 808, Collaborative Arrangements . We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under our agreement, we perform the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) we satisfy each performance obligation. As part of the accounting for these arrangements, we must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. We use key assumptions to determine the stand-alone selling price, which may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success. We recognize revenue in one of two ways, over time or at a point in time. We recognize revenue over time when we are executing on our performance obligation over time and our partner receives benefit over time. For example, we recognize revenue over time when we provide research and development services. We recognize revenue at a point in time when we transfer control of a distinct performance obligation to our partner. For example, if a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development costs include: salaries and employee-related expenses, including stock-based compensation and benefits for personnel in research and product development functions; costs associated with conducting our preclinical, development and regulatory activities, including fees paid to third-party professional consultants, service providers and our scientific, therapeutic and clinical advisors; costs to acquire, develop and manufacture preclinical study and clinical trial materials; costs incurred under clinical trial agreements with clinical research organizations and investigative sites; costs for laboratory supplies; payments related to licensed products and technologies; allocated facilities and information technology costs; and depreciation.
Patent Costs	Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain.
Stock-Based Compensation	Stock-Based Compensation We evaluate our stock-based compensation arrangements under ASC Topic 718, Compensation – Stock Compensation. Stock-based compensation expense represents the grant date fair value of employee stock option and restricted stock unit grants recognized as expense over the requisite service period of the awards (usually the vesting period) on a straight-line basis. We estimate fair value of stock option grants using the Black-Scholes option pricing model. We estimate the fair value using assumptions, including the risk-free interest rate, the expected volatility of a peer group of similar companies, the expected term of the awards and the expected dividend yield. These estimates involve inherent uncertainties and the application of management’s judgment. If factors change and different assumptions are used, our stock-based compensation expense could be materially different in the future.
Income Taxes	Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized as income in the period that includes the enactment date. We recognize net deferred tax assets to the extent that we believe these assets are more likely than not to be realized. In making such a determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations. If we determine that we would be able to realize the deferred tax assets in the future in excess of their net recorded amount, we would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. We record uncertain tax positions on the basis of a two-step process whereby (1) we determine whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, we recognize the largest amount of tax benefit that is more than 50 % likely to be realized upon ultimate settlement with the related tax authority. We recognize interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted 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 common stock and common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of convertible preferred stock, warrants for common stock, options and restricted stock units outstanding under our stock option plans and inducement grants and estimated shares to be purchased under our employee stock purchase plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common share equivalents): Years Ended December 31, 2022 2021 2020 Common stock warrants 13,760 13,760 13,904 Common stock options and restricted stock units 3,077,608 1,420,050 584,211 Employee stock purchase plan 34,588 2,045 1,602 Total 3,125,956 1,435,855 599,717 The following table summarizes our net loss per share (in thousands, except per share data): Years Ended December 31, 2022 2021 2020 Numerator: Net loss attributable to aTyr Pharma, Inc. $ ( 45,338 ) $ ( 33,768 ) $ ( 16,224 ) Denominator: Weighted average common shares outstanding 28,419,569 19,080,878 9,160,269 Weighted average common shares subject to repurchase — — — Shares used in computing net loss per share, basic and diluted 28,419,569 19,080,878 9,160,269 Net loss per share - basic and diluted $ ( 1.60 ) $ ( 1.77 ) $ ( 1.77 )
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses (Topic 326), to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in Topic 326 replace the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Topic 326 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years for smaller reporting companies. We do not expect the adoption of the amendments in Topic 326 to have a material effect on our consolidated financial position or results of operations when such amendment is effective.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss Per Share	Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common share equivalents): Years Ended December 31, 2022 2021 2020 Common stock warrants 13,760 13,760 13,904 Common stock options and restricted stock units 3,077,608 1,420,050 584,211 Employee stock purchase plan 34,588 2,045 1,602 Total 3,125,956 1,435,855 599,717
Summary of Net Loss Per Share	The following table summarizes our net loss per share (in thousands, except per share data): Years Ended December 31, 2022 2021 2020 Numerator: Net loss attributable to aTyr Pharma, Inc. $ ( 45,338 ) $ ( 33,768 ) $ ( 16,224 ) Denominator: Weighted average common shares outstanding 28,419,569 19,080,878 9,160,269 Weighted average common shares subject to repurchase — — — Shares used in computing net loss per share, basic and diluted 28,419,569 19,080,878 9,160,269 Net loss per share - basic and diluted $ ( 1.60 ) $ ( 1.77 ) $ ( 1.77 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of Assets Measured at Fair Value on Recurring Basis	Assets measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements Using Total Quoted Prices in Markets Identical Significant Significant As of December 31, 2022 Assets: Current: Cash equivalents $ 8,585 $ 8,585 $ — $ — Available-for-sale investments: Commercial paper 28,074 — 28,074 — Corporate debt securities 26,094 — 26,094 — Municipal bonds 1,997 — 1,997 — Total available-for-sale investments 56,165 — 56,165 — Total assets measured at fair value $ 64,750 $ 8,585 $ 56,165 $ — Fair Value Measurements Using Total Quoted Prices in Markets Identical Significant Significant As of December 31, 2021 Assets: Current: Cash equivalents $ 2,052 $ 2,052 $ — $ — Available-for-sale investments: Commercial paper 36,921 — 36,921 — Corporate debt securities 55,713 — 55,713 — Municipal bonds 12,941 — 12,941 — Total available-for-sale investments 105,575 — 105,575 — Total assets measured at fair value $ 107,627 $ 2,052 $ 105,575 $ —
Schedule of Available-for-sale Investments	As of December 31, 2022 and 2021, available-for-sale investments are detailed as follows (in thousands): December 31, 2022 Contractual Maturity Gross Gross Gross Market Value Available-for-sale investments: Commercial paper Within 1 year $ 28,121 $ — $ ( 47 ) $ 28,074 Corporate debt securities 1 to 2 years 26,401 — ( 307 ) 26,094 Municipal bonds Within 1 year 2,026 — ( 29 ) 1,997 $ 56,548 $ — $ ( 383 ) $ 56,165 December 31, 2021 Contractual Maturity Gross Gross Gross Market Value Available-for-sale investments: Commercial paper Within 1 year $ 36,956 $ — $ ( 35 ) $ 36,921 Corporate debt securities 1 to 2 years 55,859 — ( 146 ) 55,713 Municipal bonds 1 to 2 years 12,973 — ( 32 ) 12,941 $ 105,788 $ — $ ( 213 ) $ 105,575

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	12 Months Ended
	Dec. 31, 2022
Balance Sheet Details [Abstract]
Schedule of Prepaid Expenses	Prepaid expenses consist of the following (in thousands): December 31, 2022 2021 Prepaid clinical and research expense $ 334 $ 557 Prepaid manufacturing expenses 2,049 4,188 Other prepaid expenses 567 478 $ 2,950 $ 5,223
Summary of Property and Equipment	Property and equipment consist of the following (in thousands): December 31, 2022 2021 Computer and office equipment $ 620 $ 616 Scientific and laboratory equipment 4,379 4,383 Tenant improvements 4,414 1,701 9,413 6,700 Less accumulated depreciation and amortization ( 6,354 ) ( 6,157 ) $ 3,059 $ 543
Summary of Accrued Expenses	Accrued expenses consist of the following (in thousands): December 31, 2022 2021 Accrued salaries, wages and benefits $ 2,781 $ 2,326 Accrued clinical and manufacturing 5,151 $ 1,004 Other accrued expenses 1,930 672 $ 9,862 $ 4,002

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Instruments [Abstract]
Schedule of Future Minimum Payments under Non-cancelable Operating Lease and Reconciliation to Operating Lease Liability	Future minimum payments under the non-cancelable operating leases and reconciliation to the operating lease liability as of December 31, 2022 were as follows (in thousands): Operating Leases 2023 $ 1,363 2024 1,961 2025 1,895 2026 1,777 2027 1,831 2028 and thereafter 11,102 Less: Amount representing interest ( 6,911 ) Present value of lease payments 13,018 Less: Current portion of operating lease liability ( 630 ) Less: Tenant improvement allowance not yet received ( 2,755 ) Long-term operating lease liability, net of current portion $ 9,633
Schedule of Future Minimum Payments under Non-cancelable Financing Lease and Reconciliation to Financing Lease Liability	Future minimum payments under the non-cancelable financing lease and reconciliation to the financing lease liability as of December 31, 2022 were as follows (in thousands): Financing Leases 2023 $ 352 2024 352 2025 352 2026 395 2027 33 Less: Amount representing interest ( 213 ) Present value of lease payments 1,271 Less: Current portion of financing lease liability ( 264 ) Long-term financing lease liability, net of current portion $ 1,007

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Summary of Stock Option Activity	Stock option activity is summarized as follows: Number of Weighted- Weighted Aggregate Outstanding as of December 31, 2021 1,412,550 $ 12.01 Granted 1,590,844 $ 3.43 Exercises ( 259 ) $ 3.77 Canceled/forfeited/expired ( 46,965 ) $ 8.59 Outstanding as of December 31, 2022 2,956,170 $ 7.45 8.47 $ —
Summary of Assumptions Used to Determine Fair Value of Employee Stock Purchase Plan	The assumptions used in the Black-Scholes option pricing model to determine the fair value of the ESPP offering were as follows: Years Ended December 31, 2022 2021 2020 Expected term (in years) 0.50 0.50 0.50 Risk-free interest rate 0.06 % – 4.54 % 0.04 % – 0.12 % 0.1 % – 1.6 % Expected volatility 51.9 % – 95.9 % 89.7 % – 108.12 % 89.7 % – 143.2 % Expected dividend yield 0.0 % 0.0 % 0.0 %
Schedule of Restricted Stock Units Activity	Occasionally, we grant restricted stock units to employees. The fair value of restricted stock is determined by the closing price of the our common stock reported on the Nasdaq Capital Market on the date of grant. Restricted stock unit activity is summarized as follows: Number of Outstanding Weighted-Average Balance as of December 31, 2021 7,500 $ 4.08 Granted 116,438 $ 5.13 Released ( 2,500 ) $ 4.13 Balance as of December 31, 2022 121,438 $ 5.09
Schedule of Allocation of Stock-Based Compensation for All Options Including Performance Options with Market Condition and Restricted Stock Units	The allocation of stock-based compensation for all options, including performance options with market condition and restricted stock units is as follows (in thousands): Years Ended December 31, 2022 2021 2020 Research and development $ 528 $ 295 $ 254 General and administrative 1,626 1,319 1,211 Total stock-based compensation expense $ 2,154 $ 1,614 $ 1,465
Summary of Warrants Outstanding	Warrants Warrants outstanding for the purchase of common stock as of December 31, 2022 were as follows: Number Exercise Price Expiration Outstanding Per Share Date 1,066 $ 281.50 July 2023 6,830 $ 43.93 November 2023 2,978 $ 50.37 June 2024 2,886 $ 51.98 December 2024 13,760
Summary of Common Stock Reserved for Future Issuance	Common Stock Reserved for Future Issuance Common stock reserved for future issuance was as follows: December 31, 2022 Common stock warrants 13,760 Common stock options and restricted stock units 3,077,608 Shares available under the 2015 equity incentive plan 962,179 Shares available under the 2022 inducement plan 98,400 Shares available under the employee stock purchase plan 801,321 4,953,268
Employee Stock Option [Member]
Summary of Assumptions Used to Determine Fair Value of Employee Stock Option Grants and Performance Options with Market Condition	The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows: Years Ended December 31, 2022 2021 2020 Expected term (in years) 5.98 – 6.08 5.50 – 6.08 5.50 – 6.08 Risk-free interest rate 1.7 % – 4.2 % 0.6 % – 1.3 % 0.3 % – 1.5 % Expected volatility 84.2 % – 86.5 % 86.3 % – 104.8 % 102.2 % – 109.7 % Expected dividend yield 0.0 % 0.0 % 0.0 %

Income Tax (Tables)

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Pretax Losses for Domestic and Foreign Operations	Pretax losses were generated by both domestic and foreign operations as follows (in thousands): Years Ended December 31, 2022 2021 2020 United States $ ( 45,086 ) $ ( 33,316 ) $ ( 15,950 ) Foreign ( 254 ) ( 458 ) ( 280 ) Worldwide pre-tax loss $ ( 45,340 ) $ ( 33,774 ) $ ( 16,230 )
Schedule of Reconciliations of the Expected Statutory Federal Income Tax	A reconciliation of the expected statutory federal income tax provision to the actual income tax provision is summarized as follows (in thousands): Years Ended December 31, 2022 2021 2020 Expected income taxes benefit at federal statutory rate $ ( 9,521 ) $ ( 7,093 ) $ ( 3,408 ) State income taxes, net of federal benefit ( 380 ) ( 2,313 ) ( 12 ) Permanent items and other 438 592 169 Stock compensation 44 90 804 Research credits ( 4,415 ) ( 1,253 ) ( 835 ) Unrecognized tax benefits 2,454 500 334 Foreign rate differential 11 21 13 Change in tax rate 34 52 ( 7 ) Change in valuation allowance 11,335 9,404 2,942 Income tax (benefit) expense $ — $ — $ —
Schedule of Significant Components of Deferred Tax Assets	Significant components of our deferred tax assets are summarized as follows (in thousands): December 31, 2022 2021 Deferred tax assets: Net operating loss carryforwards $ 52,752 $ 48,833 Capitalized research and development expenses 22,576 18,086 Research credits and other state credits 16,021 13,695 Intangible assets 1,278 1,465 Reserve and accruals 596 641 Share-based compensation expense 1,628 1,369 Lease liability 2,157 290 Total tax assets 97,008 84,379 Valuation allowance ( 95,484 ) ( 84,112 ) Total deferred tax assets $ 1,524 $ 267 Deferred tax liabilities: Right of use lease assets ( 1,524 ) ( 267 ) Total deferred tax liabilities ( 1,524 ) ( 267 ) Net deferred tax assets $ — $ —
Schedule of Activity Related to Unrecognized Tax Benefits	The activity related to our unrecognized tax benefits is summarized as follows (in thousands): December 31, 2022 2021 2020 Balance as of beginning of year $ 22,232 $ 21,707 $ 21,302 Increase (decrease) related to prior year tax positions ( 48 ) ( 9 ) 3 Increase related to current year tax positions 2,961 534 402 Balance as of end of year $ 25,145 $ 22,232 $ 21,707

Organization, Business and Ba_2

Organization, Business and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Feb. 28, 2023 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Description Of Business [Line Items]
Accumulated deficit			$ (417,634)	$ (372,296)
Cash equivalents, available-for-sale investments and restricted cash			69,300
Restricted cash			$ 3,165	$ 0	$ 0
Number of operating segment | Segment			1
Kyorin Pharmaceutical Co Ltd [Member] | Subsequent Events [Member]
Description Of Business [Line Items]
Milestone payments received	$ 10,000
Public Offerings [Member]
Description Of Business [Line Items]
Proceeds from Issuance of Common Stock		$ 80,600
Public Offerings [Member] | Subsequent Events [Member]
Description Of Business [Line Items]
Proceeds from Issuance of Common Stock	$ 52,000
Public Offerings [Member] | Common Stock [Member]
Description Of Business [Line Items]
Number of shares issued and sold | shares		10,781,250
Shares Issued, Price Per Share | $ / shares		$ 8
Public Offerings [Member] | Common Stock [Member] | Subsequent Events [Member]
Description Of Business [Line Items]
Number of shares issued and sold | shares	23,125,000
Shares Issued, Price Per Share | $ / shares	$ 2.25
Pangu BioPharma [Member] | Hong Kong [Member]
Description Of Business [Line Items]
Majority-owned subsidiary percentage			98%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Significant Accounting Policies [Line Items]
Impairment charges on investment securities	$ 0
Aggregate value of investment securities	56,165,000	$ 105,575,000
Unrealized gain between amortized cost and fair value of investment securities	400,000	$ 200,000
Impairment of long lived assets	$ 0
Maximum [Member]
Significant Accounting Policies [Line Items]
Maturity period of investment securities	2 years	1 year
Estimated useful life of property and equipment	7 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment	3 years
Percentage of tax benefit to be realized upon settlement	50%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in calculation of diluted net loss per share	3,125,956	1,435,855	599,717
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in calculation of diluted net loss per share	13,760	13,760	13,904
Common Stock Options and Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in calculation of diluted net loss per share	3,077,608	1,420,050	584,211
Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in calculation of diluted net loss per share	34,588	2,045	1,602

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss attributable to aTyr Pharma, Inc.	$ (45,338)	$ (33,768)	$ (16,224)	$ (16,224)
Denominator:
Weighted average common shares outstanding	28,419,569	19,080,878	9,160,269
Weighted average common shares subject to repurchase	0	0	0
Shares used in computing net loss per share, basic	28,419,569	19,080,878	9,160,269
Shares used in computing net loss per share, diluted	28,419,569	19,080,878	9,160,269
Net loss per share - basic	$ (1.60)	$ (1.77)	$ (1.77)
Net loss per share - diluted	$ (1.60)	$ (1.77)	$ (1.77)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 8,585	$ 2,052
Total assets measured at fair value	64,750	107,627
Available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	56,165	105,575
Available-for-sale [Member] | Short-term Investments | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	28,074	36,921
Available-for-sale [Member] | Short-term Investments | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	26,094	55,713
Available-for-sale [Member] | Short-term Investments | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,997	12,941
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	8,585	2,052
Total assets measured at fair value	8,585	2,052
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	56,165	105,575
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	56,165	105,575
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Short-term Investments | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	28,074	36,921
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Short-term Investments | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	26,094	55,713
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Short-term Investments | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	$ 1,997	$ 12,941

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Available-for-sale Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	$ 56,548	$ 105,788
Gross Unrealized Losses	(383)	(213)
Market Value	56,165	105,575
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	28,121	36,956
Gross Unrealized Losses	(47)	(35)
Market Value	28,074	36,921
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	2,026	12,973
Gross Unrealized Losses	(29)	(32)
Market Value	1,997	12,941
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	26,401	55,859
Gross Unrealized Losses	(307)	(146)
Market Value	$ 26,094	$ 55,713

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Position	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Available for sale investments number of positions	25
Available-for-sale, investments in unrealized loss positions, number of positions	20
Available-for-sale, investments in unrealized loss positions, greater than 12 months	12
Available-for-sale, investments in unrealized loss positions, greater than twelve months, market value | $	$ 24.2
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments gross unrealized loss positions, period		12 months
Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments gross unrealized loss positions, period	12 months

License, Collaboration and Ot_2

License, Collaboration and Other Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2023	Dec. 31, 2022	Dec. 31, 2020
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue		$ 10,386	$ 10,455
Collaboration Revenue [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue		10,000
Additional Collaboration Revenue [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue		$ 400
Kyorin Pharmaceutical Co Ltd [Member] | Subsequent Events [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront payment received	$ 20,000
Milestone payments received	10,000
Development Regulatory And Sales Milestones [Member] | Kyorin Pharmaceutical Co Ltd [Member] | Subsequent Events [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Remaining receivable based on achievement of research milestones	$ 155,000

Balance Sheet Details - Summary

Balance Sheet Details - Summary of Prepaid Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Prepaid Expenses [Line Items]
Prepaid expenses	$ 2,950	$ 5,223
Prepaid Clinical and Research Expense [Member]
Prepaid Expenses [Line Items]
Prepaid expenses	334	557
Prepaid Manufacturing Expenses [Member]
Prepaid Expenses [Line Items]
Prepaid expenses	2,049	4,188
Other Prepaid Expenses [Member]
Prepaid Expenses [Line Items]
Prepaid expenses	$ 567	$ 478

Balance Sheet Details - Summa_2

Balance Sheet Details - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, Gross	$ 9,413	$ 6,700
Less accumulated depreciation and amortization	(6,354)	(6,157)
Property and equipment, Net	3,059	543
Computer and Office Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, Gross	620	616
Scientific and Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, Gross	4,379	4,383
Tenant Improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, Gross	$ 4,414	$ 1,701

Balance Sheet Details - Additio

Balance Sheet Details - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 232	$ 475	$ 569

Balance Sheet Details - Summa_3

Balance Sheet Details - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accrued Liabilities, Current [Abstract]
Accrued salaries, wages and benefits	$ 2,781	$ 2,326
Accrued clinical and manufacturing	5,151	1,004
Other accrued expenses	1,930	672
Accrued expenses	$ 9,862	$ 4,002

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended		12 Months Ended
	May 31, 2022 USD ($) ft²	Jul. 31, 2018 ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 13, 2023 ft²
Commitments and Contingencies [Line Items]
Lease space | ft²	23,696	20,508				24,494
Lease extended maturity Term		2023-05
Operating lease, lease not yet commenced, term of contract	124 months
Operating lease, lease not yet commenced, option to extend			We also have one option to extend the Lease Term for five years.
Operating lease, lease not yet commenced, existence of option to extend	true
Operating lease, lease not yet commenced, extension term	5 years
Base rent per square foot	$ 5.75
Annual upward adjustments on base rate, percentage	3%
Allowance for tenant improvements	$ 5,500,000
Additional allowance for tenant improvements	$ 600,000
Base rent amortized percentage	8%
Security deposit			$ 700,000
Lease, option to extend		false
Operating lease expense			$ 1,500,000	$ 1,000,000	$ 1,000,000
Operating lease, weighted average remaining lease term			9 years 10 months 24 days	1 year 4 months 24 days
Operating lease, weighted average discount rate			8.80%	9.60%
Financing lease, term of contract			48 months
Financing lease, weighted-average remaining lease term			3 years 8 months 12 days
Financing lease, weighted-average discount rate			7.90%
Leased Equipment [Member] | Restricted Cash [Member]
Commitments and Contingencies [Line Items]
Security deposit			$ 2,400,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Payments under Non-cancelable Operating Lease and Reconciliation to Operating Lease Liability (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases, Operating [Abstract]
2023	$ 1,363
2024	1,961
2025	1,895
2026	1,777
2027	1,831
2028 and thereafter	11,102
Less: Amount representing interest	(6,911)
Present value of lease payments	13,018
Less: Current portion of operating lease liability	(630)	$ (980)
Less: Tenant improvement allowance not yet received	(2,755)
Long-term operating lease liability, net of current portion	$ 9,633	$ 398

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Future Minimum Payments under Non-cancelable Financing Lease and Reconciliation to Financing Lease Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Finance Lease, Liability [Abstract]
2023	$ 352
2024	352
2025	352
2026	395
2027	33
Less: Amount representing interest	(213)
Present value of lease payments	1,271
Less: Current portion of financing lease liability	(264)	$ 0
Long-term financing lease liability, net of current portion	$ 1,007	$ 0

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)

1 Months Ended

2 Months Ended

3 Months Ended

12 Months Ended

Feb. 28, 2023

Mar. 31, 2022

Sep. 30, 2021

Sep. 30, 2020

Apr. 30, 2015

Mar. 14, 2023

Mar. 31, 2022

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Apr. 30, 2022

Mar. 31, 2021

Nov. 30, 2020

May 31, 2019

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Commission Rate Equal To Gross Proceeds1

3%

3%

Number of common stock shares reserved for issuance

4,953,268

Stock options granted

1,590,844

Weighted average exercise price, granted

$ 3.43

Weighted average grant date fair value of options granted

$ 2.49

$ 3.82

$ 3.39

Total grant date fair value of restricted stock units vested

$ 597,000

$ 16,000

$ 21,000

Aggregate intrinsic value of stock options exercised

1,000

80,000

0

Aggregate intrinsic value of restricted stock units

6,000

$ 31,000

34,000

Unrecognized share based compensation expense related to unvested stock options

5,500,000

Unrecognized share based compensation expense related to restricted stock units

$ 400,000

Inducement Pool Non Qualified Option [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of common stock shares reserved for issuance

300,000

300,000

Employee Stock Option [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Unrecognized cost expected to be recognized over a weighted average period

3 years

Restricted Stock Unit [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Unrecognized cost expected to be recognized over a weighted average period

2 years 2 months 12 days

2014 Plan [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Maximum term for stock option plan grant

10 years

Options vesting period

4 years

2015 Stock Option and Incentive Plan [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Maximum term for stock option plan grant

10 years

Options vesting period

4 years

Options vesting period, description

For an initial grant to an employee, 25% of the options generally vest on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years. For subsequent grants to an employee, the options generally vest monthly over a four-year term.

2015 Stock Option and Incentive Plan [Member] | One Year Anniversary [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Option vesting percentage

25%

Aspire Capital [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares issued and sold

0

3,000,000

Shares Issued, Price Per Share

$ 5.09

Proceeds from Issuance of Common Stock

$ 15,200,000

Commitment to purchase shares

$ 20,000,000

Long-term purchase commitment, period

30 months

Long-term purchase commitment, description

upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $20.0 million of shares of our common stock at our request from time to time during the 30 month term of the Purchase Agreement. Concurrently with entering into the Purchase Agreement

Public Offerings [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Proceeds from Issuance of Common Stock

$ 80,600,000

Public Offerings [Member] | Subsequent Event [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Proceeds from Issuance of Common Stock

$ 52,000,000

ATM Offering Program [Member] | Subsequent Event [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Proceeds from Issuance of Common Stock

$ 1,200,000

ATM Offering Program [Member] | H.C. Wainwright & Co., LLC [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Proceeds from Issuance of Common Stock

$ 9,600,000

$ 6,400,000

Commission rate equal to gross proceeds

3%

ATM Offering Program [Member] | H.C. Wainwright & Co., LLC [Member] | Sale Agreement [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Agreed upon value of sale of common stock per transaction

$ 20,000,000

ATM Offering Program [Member] | H.C. Wainwright & Co., LLC [Member] | Sale Agreement [Member] | Maximum [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Agreed upon value of sale of common stock per transaction

$ 20,000,000

$ 10,000,000

ATM Offering Program [Member] | Jefferies LLC [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Shares Issued, Price Per Share

$ 3.09

Proceeds from Issuance of Common Stock

$ 4,000,000

ATM Offering Program [Member] | Jefferies LLC [Member] | Sale Agreement [Member] | Maximum [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Agreed upon value of sale of common stock per transaction

$ 65,000,000

ATM Offering Program [Member] | Jones Trading Institutional Services LLC [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Shares Issued, Price Per Share

$ 6.07

$ 6.07

$ 4.75

Proceeds from Issuance of Common Stock

$ 1,500,000

$ 4,400,000

ATM Offering Program [Member] | Jones Trading Institutional Services LLC [Member] | Sale Agreement [Member] | Maximum [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Agreed upon value of sale of common stock per transaction

$ 25,000,000

IPO [Member] | 2015 Stock Option and Incentive Plan [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Effective date of plan

May 06, 2015

Number of common stock shares reserved for issuance

962,179

IPO [Member] | 2015 Employee Stock Purchase Plan [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Effective date of plan

May 06, 2015

Number of common stock shares reserved for issuance

801,321

Common Stock [Member] | Inducement Pool Non Qualified Option [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Options vesting period

4 years

Stock options granted

205,600

Exercise price, granted

$ 3.94

Common Stock [Member] | One Year Anniversary [Member] | Inducement Pool Non Qualified Option [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Options vesting period

1 year

Option vesting percentage

25%

Common Stock [Member] | Share-Based Payment Arrangement, Tranche Two [Member] | Inducement Pool Non Qualified Option [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Options vesting period

3 years

Option vesting percentage

75%

Common Stock [Member] | Maximum [Member] | Inducement Pool Non Qualified Option [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Options vesting period

10 years

Common Stock [Member] | Public Offerings [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares issued and sold

10,781,250

Shares Issued, Price Per Share

$ 8

Common Stock [Member] | Public Offerings [Member] | Subsequent Event [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares issued and sold

23,125,000

Shares Issued, Price Per Share

$ 2.25

Common Stock [Member] | ATM Offering Program [Member] | Subsequent Event [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares issued and sold

516,453

Shares Issued, Price Per Share

$ 2.35

Common Stock [Member] | ATM Offering Program [Member] | H.C. Wainwright & Co., LLC [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares issued and sold

1,988,254

1,657,075

Shares Issued, Price Per Share

$ 4.99

$ 4.07

Common Stock [Member] | ATM Offering Program [Member] | Jefferies LLC [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares issued and sold

1,421,627

Common Stock [Member] | ATM Offering Program [Member] | Jones Trading Institutional Services LLC [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares issued and sold

260,455

986,267

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number of Outstanding Stock Options, Beginning Balance | shares	1,412,550
Number of Outstanding Stock Options, Granted | shares	1,590,844
Number of Outstanding Stock Options, Exercises | shares	(259)
Number of Outstanding Stock Options, Canceled/forfeited/expired | shares	(46,965)
Number of Outstanding Stock Options, Ending Balance | shares	2,956,170
Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 12.01
Weighted Average Exercise Price, Granted | $ / shares	3.43
Weighted Average Exercise Price, Exercises | $ / shares	3.77
Weighted Average Exercise Price, Canceled/forfeited/expired | $ / shares	8.59
Weighted Average Exercise Price, Ending Balance | $ / shares	$ 7.45
Weighted Average Contractual Term, Outstanding	8 years 5 months 19 days

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Assumptions Used to Determine Fair Value of Employee Stock Option Grants, Employee Stock Purchase Plan and Performance Options with Market Condition (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months
Risk-free interest rate, minimum	0.06%	0.04%	0.10%
Risk-free interest rate, maximum	4.54%	0.12%	1.60%
Expected volatility, minimum	51.90%	89.70%	89.70%
Expected volatility, maximum	95.90%	108.12%	143.20%
Expected dividend yield	0%	0%	0%
Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.70%	0.60%	0.30%
Risk-free interest rate, maximum	4.20%	1.30%	1.50%
Expected volatility, minimum	84.20%	86.30%	102.20%
Expected volatility, maximum	86.50%	104.80%	109.70%
Expected dividend yield	0%	0%	0%
Employee Stock Option [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 11 months 23 days	5 years 6 months	5 years 6 months
Employee Stock Option [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 29 days	6 years 29 days

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Restricted Stock Unit Activity (Detail) - Restricted Stock Unit [Member]	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of Outstanding Restricted Stock Units, Beginning Balance | shares	7,500
Number of Outstanding Restricted Stock Units, Granted | shares	116,438
Number of Outstanding Restricted Stock Units, Released | shares	(2,500)
Number of Outstanding Restricted Stock Units, Ending Balance | shares	121,438
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 4.08
Weighted Average Grant Date Fair Value, Granted | $ / shares	5.13
Weighted Average Grant Date Fair Value, Released | $ / shares	4.13
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 5.09

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Allocation of Stock-Based Compensation for All Options Including Performance Options with Market Condition and Restricted Stock Units (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,154	$ 1,614	$ 1,465
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	528	295	254
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,626	$ 1,319	$ 1,211

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Warrants Outstanding (Detail)	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Warrant One [Member]
Class Of Warrant Or Right [Line Items]
Number Outstanding	1,066
Exercise Price Per Share | $ / shares	$ 281.50
Expiration Date	2023-07
Warrant Two [Member]
Class Of Warrant Or Right [Line Items]
Number Outstanding	6,830
Exercise Price Per Share | $ / shares	$ 43.93
Expiration Date	2023-11
Warrant Three [Member]
Class Of Warrant Or Right [Line Items]
Number Outstanding	2,978
Exercise Price Per Share | $ / shares	$ 50.37
Expiration Date	2024-06
Warrant Four [Member]
Class Of Warrant Or Right [Line Items]
Number Outstanding	2,886
Exercise Price Per Share | $ / shares	$ 51.98
Expiration Date	2024-12
Warrant Five [Member]
Class Of Warrant Or Right [Line Items]
Number Outstanding	13,760

Stockholders' Equity - Summar_4

Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2022 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	4,953,268
Common Stock Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	13,760
Common Stock Options and Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	3,077,608
Shares Available Under the 2015 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	962,179
Shares Available Under the 2022 Inducement Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	98,400
Shares Available Under the Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	801,321

Income Tax - Schedule of Pretax

Income Tax - Schedule of Pretax Losses for Domestic and Foreign Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
United States	$ (45,086)	$ (33,316)	$ (15,950)
Foreign	(254)	(458)	(280)
Worldwide pre-tax loss	$ (45,340)	$ (33,774)	$ (16,230)

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax [Line Items]
Income tax (benefit) provision	$ 0	$ 0	$ 0
Valuation allowance	95,484,000	84,112,000
Capitalized R&D costs	$ 41,000,000
Period of change in ownership	3 years
Percentage of change in ownership	50%
Unrecognized tax benefits, income tax penalties and interest accrued	$ 0	$ 0	$ 0
Change in unrecognized tax benefits	$ 0
Federal [Member]
Income Tax [Line Items]
Amortization period of capitalized R&D costs	5 years
NOLs carryforwards	$ 221,000,000
NOLs carryforwards not subject to expiration	108,500,000
NOLs carryforwards subject to expiration	$ 112,500,000
NOLs carryforwards expiration year	2025
Research and development credit carryforward	$ 8,300,000
Research and development credit carryforward expiration year	2026
Federal [Member] | Orphan Drug Credits [Member]
Income Tax [Line Items]
Research and development credit carryforward	$ 15,400,000
Research and development credit carryforward expiration year	2035
State [Member]
Income Tax [Line Items]
NOLs carryforwards subject to expiration	$ 194,400,000
NOLs carryforwards expiration year	2022
Research and development credit carryforward	$ 5,200,000
Foreign [Member]
Income Tax [Line Items]
Amortization period of capitalized R&D costs	15 years
NOLs carryforwards not subject to expiration	$ 9,000,000

Income Tax - Schedule of Reconc

Income Tax - Schedule of Reconciliations of the Expected Statutory Federal Income Tax (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Expected income taxes benefit at federal statutory rate	$ (9,521,000)	$ (7,093,000)	$ (3,408,000)
State income taxes, net of federal benefit	(380,000)	(2,313,000)	(12,000)
Permanent items and other	438,000	592,000	169,000
Stock compensation	44,000	90,000	804,000
Research credits	(4,415,000)	(1,253,000)	(835,000)
Unrecognized tax benefits	2,454,000	500,000	334,000
Foreign rate differential	11,000	21,000	13,000
Change in tax rate	34,000	52,000	(7,000)
Change in valuation allowance	11,335,000	9,404,000	2,942,000
Income tax (benefit) expense	$ 0	$ 0	$ 0

Income Tax - Schedule of Signif

Income Tax - Schedule of Significant Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 52,752	$ 48,833
Capitalized research and development expenses	22,576	18,086
Research credits and other state credits	16,021	13,695
Intangible assets	1,278	1,465
Reserve and accruals	596	641
Share-based compensation expense	1,628	1,369
Lease liability	2,157	290
Total tax assets	97,008	84,379
Valuation allowance	(95,484)	(84,112)
Total deferred tax assets	1,524	267
Deferred tax liabilities:
Right of use lease assets	(1,524)	(267)
Total deferred tax liabilities	$ (1,524)	$ (267)

Income Tax - Schedule of Activi

Income Tax - Schedule of Activity Related to Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Balance as of beginning of year	$ 22,232	$ 21,707	$ 21,302
Increase (decrease) related to prior year tax positions	(48)	(9)	3
Increase related to current year tax positions	2,961	534	402
Balance as of end of year	$ 25,145	$ 22,232	$ 21,707

Employee Benefits - Additional

Employee Benefits - Additional Information (Detail) - 401 (k) Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Contribution Plan Disclosure [Line Items]
Policy approved month and year	2015-04
Date of Policy beginning	Jun. 01, 2015
Percentage of match employee contribution	50%
Percentage of participants's annual salary	6%
Discretionary contribution	$ 0.2	$ 0.2	$ 0.2

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended		2 Months Ended
	Feb. 06, 2023	Feb. 28, 2023	Sep. 30, 2021	Mar. 14, 2023	Mar. 10, 2023
Public Offerings [Member]
Subsequent Event [Line Items]
Proceeds from Issuance of Common Stock			$ 80.6
Public Offerings [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares issued and sold			10,781,250
Shares Issued, Price Per Share			$ 8
Subsequent Events [Member] | Public Offerings [Member]
Subsequent Event [Line Items]
Proceeds from Issuance of Common Stock		$ 52
Subsequent Events [Member] | Public Offerings [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares issued and sold		23,125,000
Shares Issued, Price Per Share		$ 2.25
Subsequent Events [Member] | ATM Offering Program [Member]
Subsequent Event [Line Items]
Proceeds from Issuance of Common Stock				$ 1.2
Subsequent Events [Member] | ATM Offering Program [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares issued and sold				516,453
Shares Issued, Price Per Share				$ 2.35
Subsequent Events [Member] | Kyorin Pharmaceutical Co Ltd [Member]
Subsequent Event [Line Items]
Milestone payments received		$ 10
Milestone payment triggered amount	$ 10
Upfront payment received		20
Subsequent Events [Member] | Kyorin Pharmaceutical Co Ltd [Member] | Development Regulatory And Sales Milestones [Member]
Subsequent Event [Line Items]
Remaining receivable based on achievement of research milestones		$ 155
Subsequent Events [Member] | Silicon Valley Bank [Member]
Subsequent Event [Line Items]
Current cash, cash equivalents, restricted cash and available-for-sale investments percentage					2%