aTyr Pharma (ATYR) 10-Q 10 May 22 2022 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 04, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Document Quarterly 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 Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		28,056,249
Entity File Number	001-37378
Entity Tax Identification Number	20-3435077
Entity Address, Address Line One	3545 John Hopkins Court
Entity Address, Address Line Two	Suite #250
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

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 8,324	$ 2,336
Available-for-sale investments	90,342	105,575
Other receivables	426	435
Prepaid expenses	4,025	5,223
Total current assets	103,117	113,569
Property and equipment, net	433	543
Right-of-use assets	1,050	1,267
Other assets	176	158
Total assets	104,776	115,537
Current liabilities:
Accounts payable	1,563	1,031
Accrued expenses	3,694	4,002
Current portion of operating lease liability	1,012	980
Total current liabilities	6,269	6,013
Long-term operating lease liability, net of current portion	133	398
Commitments and contingencies (Note 4)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 undesignated authorized shares; Class X Convertible Preferred Stock issued and outstanding shares – 0 as of March 31, 2022 (unaudited) and December 31, 2021, respectively
Common stock, $0.001 par value per share; 42,500,000 authorized shares as of March 31, 2022 and December 31, 2021, respectively; issued and outstanding shares – 28,056,249 (unaudited) and 27,793,035 as of March 31, 2022 and December 31, 2021, respectively	28	28
Additional paid-in capital	483,730	481,832
Accumulated other comprehensive loss	(759)	(263)
Accumulated deficit	(384,449)	(372,296)
Total aTyr Pharma, Inc. stockholders’ equity	98,550	109,301
Noncontrolling interest in Pangu BioPharma Limited	(176)	(175)
Total stockholders’ equity	98,374	109,126
Total liabilities and stockholders’ equity	$ 104,776	$ 115,537

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	42,500,000	42,500,000
Common stock, shares issued	28,056,249	27,793,035
Common stock, shares outstanding	28,056,249	27,793,035
Class X Convertible Preferred Stock [Member]
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 8,896	$ 4,516
General and administrative	3,482	2,686
Total operating expenses	12,378	7,202
Loss from operations	(12,378)	(7,202)
Total other income (expense), net	224	47
Consolidated net loss	(12,154)	(7,155)
Net loss attributable to noncontrolling interest in Pangu BioPharma Limited	1	4
Net loss attributable to aTyr Pharma, Inc.	$ (12,153)	$ (7,151)
Net loss per share, basic and diluted	$ (0.44)	$ (0.51)
Shares used in computing net loss per share, basic and diluted	27,818,379	14,103,783

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net loss	$ (12,154)	$ (7,155)
Other comprehensive loss:
Change in unrealized loss on available-for-sale investments, net of tax	(496)	(14)
Comprehensive loss	(12,650)	(7,169)
Comprehensive loss attributable to noncontrolling interest in Pangu BioPharma Limited	1	4
Comprehensive loss attributable to aTyr Pharma, Inc. common stockholders	$ (12,649)	$ (7,165)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Other Comprehensive Gain/(Loss) [Member]	Accumulated Deficit [Member]	Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2020	$ 31,484	$ 11	$ 370,210	$ (43)	$ (338,528)	$ (166)
Begining balance, Shares at Dec. 31, 2020		11,018,954
Issuance of common stock upon release of restricted stock units, shares		4,177
Issuance of common stock from at-the-market offerings, net of offering costs	9,621	$ 2	9,619
Issuance of common stock from at the market offerings, net of offering costs, shares		1,988,254
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	360		360
Net unrealized loss on investments, net of tax	(14)			(14)
Net loss	(7,155)				(7,151)	(4)
Ending balance at Mar. 31, 2021	49,532	$ 16	395,422	(57)	(345,679)	(170)
Ending balance, Shares at Mar. 31, 2021		16,011,385
Beginning balance at Dec. 31, 2021	109,126	$ 28	481,832	(263)	(372,296)	(175)
Begining 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 from at-the-market offerings, net of offering costs	$ 1,480		1,480
Issuance of common stock from at the market offerings, net of offering costs, shares		260,455
Stock-based compensation	417		417
Net unrealized loss on investments, net of tax	(496)			(496)
Net loss	(12,154)				(12,153)	(1)
Ending balance at Mar. 31, 2022	$ 98,374	$ 28	$ 483,730	$ (759)	$ (384,449)	$ (176)
Ending balance, Shares at Mar. 31, 2022		28,056,249

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Consolidated net loss	$ (12,154)	$ (7,155)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	81	121
Stock-based compensation	417	360
Amortization of premium of available-for-sale investment securities	237	51
Amortization of right-of-use assets	217	176
Gain on disposal of property and equipment	(89)
Changes in operating assets and liabilities:
Other receivables	9	1,950
Prepaid expenses and other assets	1,180	395
Accounts payable and accrued expenses	216	(1,521)
Operating lease liability	(233)	(204)
Net cash used in operating activities	(10,119)	(5,827)
Cash flows from investing activities:
Purchases of property and equipment	(43)	(17)
Purchases of available-for-sale investment securities		(25,678)
Maturities of available-for-sale investment securities	14,500	2,300
Proceeds from sale of property and equipment	169
Net cash provided by (used in) investing activities	14,626	(23,395)
Cash flows from financing activities:
Proceeds from issuance of common stock through option exercises	1
Proceeds from issuance of common stock from at-the-market offerings, net of offering costs	1,480	9,621
Proceeds from issuance of common stock from committed purchase agreement, net of offering costs		15,236
Net cash provided by financing activities	1,481	24,857
Net change in cash and cash equivalents	5,988	(4,365)
Cash and cash equivalents at beginning of period	2,336	16,952
Cash and cash equivalents at the end of period	$ 8,324	$ 12,587

Organization, Business, Basis o

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies	1. Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies Organization and Business aTyr Pharma, Inc. (we, us, and our) was incorporated in the State of Delaware on September 8, 2005. We are a biotherapeutics company engaged in the discovery and development of innovative medicines based on our proprietary tRNA synthetase biology platform. Principles of Consolidation Our condensed 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. Unaudited Interim Financial Information The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (U.S. GAAP) and follow the requirements of the U.S. Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. In our opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of our financial position and our results of operations and cash flows for periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with our financial statements and accompanying notes for the fiscal year ended December 31, 2021, contained in our Annual Report on Form 10-K filed with the SEC on March 15, 2022. The results of the interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period. Risks and Uncertainties The impact of the ongoing COVID-19 pandemic has been and will likely continue to be extensive in many aspects of society, which has resulted in and will likely continue to result in significant disruptions to the global economy, as well as businesses and capital markets around the world. Impacts to our business have included delayed enrollment of our now completed Phase 1b/2a clinical trial in patients with pulmonary sarcoidosis and the discontinuation of some patients in that trial, temporary closures of portions of our facilities and those of our licensees and collaborators, disruptions or restrictions on our employee’s ability to travel and delays in certain research and development activities. Other potential impacts to our business include, but are not limited to disruptions to or delays in planned clinical trials, third-party manufacturing supply and other operations, inflation, the potential diversion of healthcare resources away from the conduct of clinical trials to focus on pandemic concerns, interruptions or delays in the operations of the U.S. Food and Drug Administration or other regulatory authorities, and our ability to raise capital and conduct business development activities. Liquidity and Financial Condition We have incurred net losses in each year since our inception in 2005, including a consolidated net loss of $12.2 million for the three months ended March 31, 2022. As of March 31, 2022, we had an accumulated deficit of $384.4 million. We believe that our existing cash, cash equivalents and available-for-sale investments of $98.7 million as of March 31, 2022 will be sufficient to meet our material cash requirements from known contractual and other obligations for a period of at least one year from the filing date of this Quarterly Report on Form 10-Q. 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. Use of Estimates Our condensed consolidated financial statements are prepared in accordance with GAAP. The preparation of our condensed 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 condensed consolidated financial statements and accompanying notes. The most significant estimates in our condensed consolidated financial statements relate to 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. 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 operating leases with an initial term of greater than 12 months, we recognize an operating 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 the operating lease is recognized on a straight-line basis over the lease term and is included in operating expenses in our condensed consolidated statements of operations. 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 operating lease ROU asset. Our ROU asset consists of an operating lease for our facility headquarters. We have a noncancelable operating lease that includes certain tenant improvement allowances and is subject to base lease payments, which escalate over the term of the lease, additional charges for common area maintenance and other costs. We currently do not have any finance leases. We do not separate lease and non-lease components of our long-term leases. Rent expense for the operating lease is recognized on a straight-line basis over the lease term and is included in our condensed consolidated statement of operations. Variable lease payments, including lease operating expenses, are recorded as incurred. Revenue Recognition We evaluate our agreements under Accounting Standard Codification ( ASC) Topic 606, Revenue from Contracts with Customers and ASC Topic 808, Collaborative Arrangements . . 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 Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares outstanding for the period. Diluted net loss per share is calculated by dividing the net loss by the weighted average number of common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of warrants for common stock, options and restricted stock units outstanding under our stock option plan 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 , as the assumed exercise or settlement of stock options, restricted stock units, and warrants, or the conversion of preferred stock are anti-dilutive . Potentially dilutive securities not considered for the calculation of diluted net loss per share are as follows (in common stock equivalents): Three Months Ended March 31, 2022 2021 Common stock warrants 13,760 13,760 Common stock options and restricted stock units 1,824,164 898,306 Employee stock purchase plan 2,045 1,602 Total 1,839,969 913,668 Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses 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 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 expect the adoption of the amendments in Topic 326 to not have a material effect in our condensed consolidated financial position or results of operations when such amendment is adopted.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	2. 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 commercial paper, corporate debt securities and asset-bask securities. 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 Active for Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) As of March 31, 2022 Assets: Current: Cash equivalents $ 8,088 $ 8,088 $ — $ — Available-for-sale investments: Commercial paper 26,828 — 26,828 — Corporate debt securities 50,671 — 50,671 — Municipal bonds 12,843 — 12,843 — Total available-for-sale investments 90,342 — 90,342 — Total assets measured at fair value $ 98,430 $ 8,088 $ 90,342 $ — Fair Value Measurements Using Total Quoted Active for Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) 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 March 31, 2022 and December 31, 2021, available-for-sale investments are detailed as follows (in thousands): March 31, 2022 Contractual Maturity Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Market Value Available-for-sale investments: Commercial paper Within 1 year $ 26,972 $ — $ (144 ) $ 26,828 Corporate debt securities 1 to 2 years 51,152 — (481 ) 50,671 Municipal bonds 1 to 2 years 12,927 — (84 ) 12,843 $ 91,051 $ — $ (709 ) $ 90,342 December 31, 2021 Contractual Maturity Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses 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 any 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. We intend, and have the ability, to hold our investments in unrealized loss positions, if any, until their amortized cost basis has been recovered. As of March 31, 2022, all available-for-sale investments had a variety of effective maturity dates of less than two years. As of March 31, 2022, all available-for-sale investments were in gross unrealized loss positions and have been in such loss positions less than twelve months.

License and Other Agreements

License and Other Agreements	3 Months Ended
	Mar. 31, 2022
License Agreements [Abstract]
License and Other Agreements	3. License 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 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. Kyorin is obligated to fund all research, development, regulatory, marketing and commercialization activities in Japan. In 2020, Kyorin completed a Phase 1 clinical trial of efzofitimod (known as KRP-R120 in Japan). The Phase 1 clinical trial, which was conducted and funded by Kyorin, was a placebo-controlled study to evaluate the safety, pharmacokinetics 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 pharmacokinetics findings were consistent with previous studies of efzofitimod. We received an $8.0 million upfront payment in January 2020 and a $2.0 milestone payment in January 2021 upon completion of enrollment in the Phase 1 clinical trial, and we are eligible to receive up to an additional $165.0 million in the aggregate upon achievement of certain development, regulatory and sales milestones, as well as tiered royalties ranging from the mid-single digits to mid-teens on 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. The $8.0 million upfront payment received from Kyorin is non-refundable and non-creditable and is considered fixed consideration. We determined that the relative stand-alone selling price was $7.9 million when the license was delivered to Kyorin in January 2020. We determined that the relative standalone selling price was $0.1 million for the free clinical trial material delivered to Kyorin in June 2020, using the “expected cost plus a margin” approach. In December 2020, Kyorin completed the last subject visit in its Phase 1 clinical trial of efzofitimod. This achievement triggered a $2.0 million milestone payment which we recognized as license and collaboration revenue in December 2020. We received the $2.0 million from Kyorin in January 2021. For each of the three months ended March 31, 2022 and 2021, there were no activities that triggered additional license and collaboration agreement revenue under the Kyorin Agreement. The remaining milestones and royalty payments under the Kyorin Agreement are variable consideration. Since 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 constrain these amounts until the future sales have occurred. Hong Kong University of Science and Technology In March 2020, our subsidiary, Pangu BioPharma, together with the Hong Kong University of Science and Technology (HKUST) was awarded a grant of approximately $750,000 to build a high-throughput platform for the development of bi-specific antibodies. The project is being funded by the Hong Kong Government’s Innovation and Technology Commission (ITC) under the Partnership Research Program (PRP). The PRP aims to support research and development projects undertaken by companies in collaboration with local universities and public research institutions. The ITC funded approximately 50% of the total estimated project cost and we contributed the remaining 50%. The research grant agreement between Pangu BioPharma, HKUST and the Government of the Hong Kong Special Administration Region became effective April 1, 2020. The term of the project was initially for two years and in December 2021, due to the ongoing COVID-19 pandemic, was extended for an additional six months with no additional costs. All the contributions provided by the ITC are paid to HKUST and we record expenses under this grant award when incurred. Expenses for the three months ended March 31, 2022 and 2021 were $41,000 and $0.2 million, respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	4. Commitments and Contingencies Facility Leases Future minimum payments under the non-cancelable facility lease and reconciliation to the operating lease liability as of March 31, 2022 were as follows (in thousands): Operating Lease 2022 $ 799 2023 404 Less: Amount representing interest (58 ) Present value of lease payments 1,145 Less: Current portion of operating lease liability (1,012 ) Long-term operating lease liability, net of current portion $ 133 For each of the three months ended March 31, 2022 and 2021, we recorded an operating lease cost of $0.2 million.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Stockholders' Equity	5. Stockholders’ Equity Underwritten Follow-On Public Offerings 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 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 (Prior 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 equal of up to 3.0% of the gross proceeds. During 2021, we sold an aggregate of 986,267 shares of common stock at an average price of $4.75 per share for net proceeds of $4.4 million under the Prior ATM Offering Program. For the three months ended March 31, 2022, we sold an aggregate of 260,455 shares of common stock at an average price of $6.07 per share for net proceeds of approximately $1.5 million under the Prior ATM Offering Program. On April 22, 2022, we terminated the Prior ATM Offering Program. Purchase Agreement In September 2020 , we sold an aggregate of 3,000,000 shares of common stock at an average price of $5.09 per share for Inducement Grants In March 2022, we adopted and our Board of Directors approved our 2022 Inducement Plan (Inducement Plan). Awards granted under our Inducement Plan are in accordance with the Nasdaq Listing Rules5635(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 the Inducement Plan is ten years. Each option vests over a period of four years, with 25% of the shares vesting on the one-year In March 2022, we granted nonstatutory stock options under our Inducement Plan to purchase an aggregate of 58,400 shares of our common stock, each with an exercise price of $5.24 per share as inducement awards to ten employees. Common Stock Reserved for Future Issuance Common stock reserved for future issuance was as follows: March 31, 2022 Common stock warrants 13,760 Common stock options and restricted stock units 1,824,164 Shares available under the 2015 equity incentive plan 72,423 Shares available under the 2022 inducement plan 241,600 Shares available under the employee stock purchase plan 71,933 2,223,880 The following table summarizes our stock option activity under all equity incentive plans for the three months ended March 31, 2022: Number of Outstanding Stock Options Weighted Average Exercise Price Outstanding as of December 31, 2021 1,412,550 $ 12.01 Granted 331,912 $ 5.47 Exercises (259 ) $ 3.77 Canceled/forfeited/expired (5,477 ) $ 4.89 Outstanding as of March 31, 2022 1,738,726 $ 10.79 The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows: March 31, 2022 2021 Expected term (in years) 6.02 – 6.08 5.99 – 6.02 Risk-free interest rate 1.7% – 2.4 % 0.6% – 0.9 % Expected volatility 85.8% – 86.5 % 104.0% – 104.8 % Expected dividend yield 0.0 % 0.0 % The following table summarizes our restricted stock unit activity under all equity incentive plans for the three months ended March 31, 2022: Number of Outstanding Restricted Stock Units Weighted Average Grant Date Fair Value Balance as of December 31, 2021 7,500 $ 4.08 Granted 80,438 $ 5.52 Released (2,500 ) $ 4.13 Balance as of March 31, 2022 85,438 $ 5.43 Stock-based Compensation The allocation of stock-based compensation for all options and restricted stock units and stock issued pursuant to our employee stock purchase plan is as follows (in thousands): March 31, 2022 2021 Research and development $ 107 $ 63 General and administrative 310 297 Total stock-based compensation expense $ 417 $ 360

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	6. Subsequent Events In April 2022, we entered into an Open Market Sale Agreement SM 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 ATM Offering Program.

Organization, Business, Basis_2

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Organization and Business	Organization and Business aTyr Pharma, Inc. (we, us, and our) was incorporated in the State of Delaware on September 8, 2005. We are a biotherapeutics company engaged in the discovery and development of innovative medicines based on our proprietary tRNA synthetase biology platform.
Principles of Consolidation	Principles of Consolidation Our condensed 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.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (U.S. GAAP) and follow the requirements of the U.S. Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. In our opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of our financial position and our results of operations and cash flows for periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with our financial statements and accompanying notes for the fiscal year ended December 31, 2021, contained in our Annual Report on Form 10-K filed with the SEC on March 15, 2022. The results of the interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period.
Risks and Uncertainties	Risks and Uncertainties The impact of the ongoing COVID-19 pandemic has been and will likely continue to be extensive in many aspects of society, which has resulted in and will likely continue to result in significant disruptions to the global economy, as well as businesses and capital markets around the world. Impacts to our business have included delayed enrollment of our now completed Phase 1b/2a clinical trial in patients with pulmonary sarcoidosis and the discontinuation of some patients in that trial, temporary closures of portions of our facilities and those of our licensees and collaborators, disruptions or restrictions on our employee’s ability to travel and delays in certain research and development activities. Other potential impacts to our business include, but are not limited to disruptions to or delays in planned clinical trials, third-party manufacturing supply and other operations, inflation, the potential diversion of healthcare resources away from the conduct of clinical trials to focus on pandemic concerns, interruptions or delays in the operations of the U.S. Food and Drug Administration or other regulatory authorities, and our ability to raise capital and conduct business development activities.
Liquidity and Financial Condition	Liquidity and Financial Condition We have incurred net losses in each year since our inception in 2005, including a consolidated net loss of $12.2 million for the three months ended March 31, 2022. As of March 31, 2022, we had an accumulated deficit of $384.4 million. We believe that our existing cash, cash equivalents and available-for-sale investments of $98.7 million as of March 31, 2022 will be sufficient to meet our material cash requirements from known contractual and other obligations for a period of at least one year from the filing date of this Quarterly Report on Form 10-Q. 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.
Use of Estimates	Use of Estimates Our condensed consolidated financial statements are prepared in accordance with GAAP. The preparation of our condensed 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 condensed consolidated financial statements and accompanying notes. The most significant estimates in our condensed consolidated financial statements relate to 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.
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 operating leases with an initial term of greater than 12 months, we recognize an operating 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 the operating lease is recognized on a straight-line basis over the lease term and is included in operating expenses in our condensed consolidated statements of operations. 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 operating lease ROU asset. Our ROU asset consists of an operating lease for our facility headquarters. We have a noncancelable operating lease that includes certain tenant improvement allowances and is subject to base lease payments, which escalate over the term of the lease, additional charges for common area maintenance and other costs. We currently do not have any finance leases. We do not separate lease and non-lease components of our long-term leases. Rent expense for the operating lease is recognized on a straight-line basis over the lease term and is included in our condensed consolidated statement of operations. Variable lease payments, including lease operating expenses, are recorded as incurred.
Revenue Recognition	Revenue Recognition We evaluate our agreements under Accounting Standard Codification ( ASC) Topic 606, Revenue from Contracts with Customers and ASC Topic 808, Collaborative Arrangements . . 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
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares outstanding for the period. Diluted net loss per share is calculated by dividing the net loss by the weighted average number of common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of warrants for common stock, options and restricted stock units outstanding under our stock option plan 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 , as the assumed exercise or settlement of stock options, restricted stock units, and warrants, or the conversion of preferred stock are anti-dilutive . Potentially dilutive securities not considered for the calculation of diluted net loss per share are as follows (in common stock equivalents): Three Months Ended March 31, 2022 2021 Common stock warrants 13,760 13,760 Common stock options and restricted stock units 1,824,164 898,306 Employee stock purchase plan 2,045 1,602 Total 1,839,969 913,668
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses 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 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 expect the adoption of the amendments in Topic 326 to not have a material effect in our condensed consolidated financial position or results of operations when such amendment is adopted.

Organization, Business, Basis_3

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Schedule of Potentially Dilutive Securities Not Considered for Calculation of Diluted Net Loss Per Share	Potentially dilutive securities not considered for the calculation of diluted net loss per share are as follows (in common stock equivalents): Three Months Ended March 31, 2022 2021 Common stock warrants 13,760 13,760 Common stock options and restricted stock units 1,824,164 898,306 Employee stock purchase plan 2,045 1,602 Total 1,839,969 913,668

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 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 Active for Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) As of March 31, 2022 Assets: Current: Cash equivalents $ 8,088 $ 8,088 $ — $ — Available-for-sale investments: Commercial paper 26,828 — 26,828 — Corporate debt securities 50,671 — 50,671 — Municipal bonds 12,843 — 12,843 — Total available-for-sale investments 90,342 — 90,342 — Total assets measured at fair value $ 98,430 $ 8,088 $ 90,342 $ — Fair Value Measurements Using Total Quoted Active for Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) 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 March 31, 2022 and December 31, 2021, available-for-sale investments are detailed as follows (in thousands): March 31, 2022 Contractual Maturity Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Market Value Available-for-sale investments: Commercial paper Within 1 year $ 26,972 $ — $ (144 ) $ 26,828 Corporate debt securities 1 to 2 years 51,152 — (481 ) 50,671 Municipal bonds 1 to 2 years 12,927 — (84 ) 12,843 $ 91,051 $ — $ (709 ) $ 90,342 December 31, 2021 Contractual Maturity Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses 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

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 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 facility lease and reconciliation to the operating lease liability as of March 31, 2022 were as follows (in thousands): Operating Lease 2022 $ 799 2023 404 Less: Amount representing interest (58 ) Present value of lease payments 1,145 Less: Current portion of operating lease liability (1,012 ) Long-term operating lease liability, net of current portion $ 133

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2022
Summary of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance was as follows: March 31, 2022 Common stock warrants 13,760 Common stock options and restricted stock units 1,824,164 Shares available under the 2015 equity incentive plan 72,423 Shares available under the 2022 inducement plan 241,600 Shares available under the employee stock purchase plan 71,933 2,223,880
Summary of Stock Option Activity	The following table summarizes our stock option activity under all equity incentive plans for the three months ended March 31, 2022: Number of Outstanding Stock Options Weighted Average Exercise Price Outstanding as of December 31, 2021 1,412,550 $ 12.01 Granted 331,912 $ 5.47 Exercises (259 ) $ 3.77 Canceled/forfeited/expired (5,477 ) $ 4.89 Outstanding as of March 31, 2022 1,738,726 $ 10.79
Schedule of Restricted Stock Unit Activity	The following table summarizes our restricted stock unit activity under all equity incentive plans for the three months ended March 31, 2022: Number of Outstanding Restricted Stock Units Weighted Average Grant Date Fair Value Balance as of December 31, 2021 7,500 $ 4.08 Granted 80,438 $ 5.52 Released (2,500 ) $ 4.13 Balance as of March 31, 2022 85,438 $ 5.43
Schedule of Allocation of Stock-Based Compensation for All Options and Restricted Stock Units and Stock Issued to Our Employee Stock Purchase Plan	The allocation of stock-based compensation for all options and restricted stock units and stock issued pursuant to our employee stock purchase plan is as follows (in thousands): March 31, 2022 2021 Research and development $ 107 $ 63 General and administrative 310 297 Total stock-based compensation expense $ 417 $ 360
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: March 31, 2022 2021 Expected term (in years) 6.02 – 6.08 5.99 – 6.02 Risk-free interest rate 1.7% – 2.4 % 0.6% – 0.9 % Expected volatility 85.8% – 86.5 % 104.0% – 104.8 % Expected dividend yield 0.0 % 0.0 %

Organization, Business, Basis_4

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Significant Accounting Policies [Line Items]
Net Income Loss	$ (12,153)	$ (7,151)
Accumulated deficit	(384,449)		$ (372,296)
Cash, cash equivalents and available-for-sale investments	$ 98,700
Pangu BioPharma [Member] | Hong Kong [Member]
Significant Accounting Policies [Line Items]
Majority-owned subsidiary percentage	98.00%

Organization, Business, Basis_5

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Not Considered for Calculation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not considered for calculation of diluted net loss per share	1,839,969	913,668
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not considered for calculation of diluted net loss per share	13,760	13,760
Common Stock Options and Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not considered for calculation of diluted net loss per share	1,824,164	898,306
Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not considered for calculation of diluted net loss per share	2,045	1,602

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	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 8,088	$ 2,052
Total assets measured at fair value	98,430	107,627
Available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	90,342	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	26,828	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	50,671	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	12,843	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	8,088	2,052
Total assets measured at fair value	8,088	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	90,342	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	90,342	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	26,828	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	50,671	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	$ 12,843	$ 12,941

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Available-for-sale Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	$ 91,051	$ 105,788
Gross Unrealized Losses	(709)	(213)
Market Value	90,342	105,575
Short-term Investments | Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	26,972	36,956
Gross Unrealized Losses	(144)	(35)
Market Value	26,828	36,921
Short-term Investments | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	12,927	12,973
Gross Unrealized Losses	(84)	(32)
Market Value	12,843	12,941
Short-term Investments | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	51,152	55,859
Gross Unrealized Losses	(481)	(146)
Market Value	$ 50,671	$ 55,713

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - Maximum [Member]	3 Months Ended
	Mar. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments effective maturity period	2 years
Available-for-sale investments gross unrealized loss positions, period	12 months

License and Other Agreements -

License and Other Agreements - Additional Information (Detail) - USD ($)	1 Months Ended				3 Months Ended
	Jan. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jan. 31, 2020	Mar. 31, 2022	Mar. 31, 2021
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront payment received				$ 8,000,000
Milestone payments received	$ 2,000,000
Hong Kong University of Science and Technology [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaborative agreement, funding received			$ 750,000
Funding of project cost, description			The ITC funded approximately 50% of the total estimated project cost and we contributed the remaining 50%. The research grant agreement between Pangu BioPharma, HKUST and the Government of the Hong Kong Special Administration Region became effective April 1, 2020
Expenses					$ 41,000	$ 200,000
Development Regulatory And Sales Milestones [Member] | Kyorin Pharmaceutical Co Ltd [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Remaining receivable based on achievement of research milestones				165,000,000
Development Regulatory And Sales Milestones [Member] | Kyorin Pharmaceutical Co Ltd [Member] | Collaboration Revenue [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront payment received					$ 0	$ 0
Stand-alone selling price of license		$ 100,000		$ 7,900,000

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Payments under Non-cancelable Operating Lease and Reconciliation to Operating Lease Liability (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Leases Operating [Abstract]
2022	$ 799
2023	404
Less: Amount representing interest	(58)
Present value of lease payments	1,145
Less: Current portion of operating lease liability	(1,012)	$ (980)
Long-term operating lease liability, net of current portion	$ 133	$ 398

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Instruments [Abstract]
Operating lease, cost	$ 0.2	$ 0.2

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2022	Sep. 30, 2020	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2021	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Commission Rate Equal To Gross Proceeds1				3.00%
Number of common stock shares reserved for issuance	2,223,880		2,223,880
Stock options granted			331,912
Inducement Pool Non Qualified Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	300,000		300,000
Aspire Capital [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issued and sold				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.
Public Offerings
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from Issuance of Common Stock					$ 80,600,000
A T M Offering Program | 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
A T M Offering Program | 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
Common Stock [Member] | Inducement Pool Non Qualified Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	4 years
Stock options granted	58,400
Exercise price, granted	$ 5.24
Common Stock [Member] | Inducement Pool Non Qualified Option | One Year Anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	1 year
Option vesting percentage	25.00%
Common Stock [Member] | Inducement Pool Non Qualified Option | Share-based Payment Arrangement, Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	3 years
Option vesting percentage	75.00%
Common Stock [Member] | Maximum [Member] | Inducement Pool Non Qualified Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	10 years
Common Stock [Member] | Public Offerings
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] | A T M Offering Program | 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 Common Stock Reserved for Future Issuance (Detail)	Mar. 31, 2022shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	2,223,880
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	1,824,164
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	72,423
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	241,600
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	71,933

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Stock Option Activity (Detail)	3 Months Ended
	Mar. 31, 2022$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Outstanding Stock Options, Beginning Balance | shares	1,412,550
Stock options granted | shares	331,912
Number of Outstanding Stock Options, Exercised | shares | shares	(259)
Number of Outstanding Stock Options, Canceled/forfeited/expired | shares	(5,477)
Number of Outstanding Stock Options, Ending Balance | shares	1,738,726
Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 12.01
Weighted Average Exercise Price, Granted | $ / shares	5.47
Weighted Average Exercise Price, Exercised | $ / shares | $ / shares	3.77
Weighted Average Exercise Price, Canceled/forfeited/expired | $ / shares	4.89
Weighted Average Exercise Price, Ending Balance | $ / shares	$ 10.79

Stockholders' Equity - Summar_3

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) - Employee Stock Option [Member]	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.70%	0.60%
Risk-free interest rate, maximum	2.40%	0.90%
Expected volatility, minimum	85.80%	104.00%
Expected volatility, maximum	86.50%	104.80%
Expected dividend yield	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 7 days	5 years 11 months 26 days
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 7 days

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member]	3 Months Ended
	Mar. 31, 2022$ / sharesshares
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	80,438
Number of Outstanding Restricted Stock Units, Released | shares	(2,500)
Number of Outstanding Restricted Stock Units, Ending Balance | shares	85,438
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 4.08
Weighted Average Grant Date Fair Value, Granted | $ / shares	5.52
Weighted Average Grant Date Fair Value, Released | $ / shares	4.13
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 5.43

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Allocation of Stock-Based Compensation for All Options and Restricted Stock Units and Stock Issued to Our Employee Stock Purchase Plan (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 417	$ 360
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	107	63
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 310	$ 297

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	Apr. 30, 2022	Mar. 31, 2021
Subsequent Event [Line Items]
Commission Rate Equal To Gross Proceeds1		3.00%
Subsequent Event [Member]
Subsequent Event [Line Items]
Commission Rate Equal To Gross Proceeds1	3.00%
Sale Agreement [Member] | A T M Offering Program | Jefferies LLC [Member] | Maximum [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Agreed upon value of sale of common stock per transaction	$ 65,000,000