0000950170-22-017401 | 10-Q | XBRL Viewer

Fair Value Measurements

6 Months Ended

Jun. 30, 2022

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-backed 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 Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of June 30, 2022
Assets:
Current:
Cash equivalents	$	7,455	$	7,455	$	—	$	—
Available-for-sale investments:
Commercial paper		26,720		—		26,720		—
Corporate debt securities		44,550		—		44,550		—
Municipal bonds		8,800		—		8,800		—
Total available-for-sale investments		80,070		—		80,070		—
Total assets measured at fair value	$	87,525	$	7,455	$	80,070	$	—


			Fair Value Measurements Using
	Total		Quoted Prices in Active Markets for Identical 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 June 30, 2022 and December 31, 2021, available-for-sale investments are detailed as follows (in thousands):


		June 30, 2022
	Contractual Maturity	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Market Value
Available-for-sale investments:
Commercial paper	Within 1 year	$	26,864	$	—	$	(144	)	$	26,720
Corporate debt securities	1 to 2 years		45,082		—		(532	)		44,550
Municipal bonds	1 to 2 years		8,883		—		(83	)		8,800
		$	80,829	$	—	$	(759	)	$	80,070


		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 June 30, 2022, all available-for-sale investments had a variety of effective maturity dates of less than two years. As of June 30, 2022, all available-for-sale investments were in gross unrealized loss positions and have been in such loss positions less than 12 months.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 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 lease for our existing office and laboratory space and reconciliation to the operating lease liability as of June 30, 2022 were as follows (in thousands):


	Operating Lease
2022	$	536
2023		404
Less: Amount representing interest		(34	)
Present value of lease payments		906
Less: Current portion of operating lease liability		(906	)
Long-term operating lease liability, net of current portion	$	—

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 June 30, 2022 were as follows (in thousands):


	Financing Lease
2022	$	49
2023		99
2024		99
2025		99
2026		97
Less: Amount representing interest		(75	)
Present value of lease payments		368
Less: Current portion of operating lease liability		(70	)
Long-term operating lease liability, net of current portion	$	298

License and Other Agreements - Additional Information (Detail) - USD ($)	1 Months Ended				3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jan. 31, 2020	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront payment received				$ 8,000,000.0
Milestone payments received	$ 2,000,000.0
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					$ 45,000	$ 100,000	$ 100,000	$ 300,000
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				165,000,000.0
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	$ 0	$ 0
Stand-alone selling price of license		$ 100,000		$ 7,900,000

Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail)	Jun. 30, 2022 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares reserved for issuance	4,971,922
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	3,048,636
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	961,351
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	128,200
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	819,975

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 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 first-in-class medicines from our proprietary tRNA synthetase 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 interim unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated 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 the periods presented. These statements do not include all disclosures required by U.S. GAAP and should be read in conjunction with our audited consolidated financial statements and accompanying notes contained in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021, as 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. Further, in February 2022, the U.S. and global financial markets experienced volatility following the invasion of Ukraine by Russia, which has led to, and may continue to lead to, additional disruptions to trade, commerce, pricing stability, credit availability and supply chain continuity globally. It is uncertain what the long-term impact of the ongoing Ukraine-Russia conflict may have on our business.

Liquidity and Financial Condition

We have incurred net losses in each year since our inception in 2005, including a consolidated net loss of $12.4 million and $24.6 million for the three and six months ended June 30, 2022, respectively. As of June 30, 2022, we had an accumulated deficit of $396.9 million. We believe that our existing cash, cash equivalents, restricted cash and available-for-sale investments of $89.3 million as of June 30, 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.

Restricted Cash

As of June 30, 2022, restricted cash consisted of approximately $0.7 million, which was held as a security deposit in conjunction with our new facility lease as discussed further below in Note 4 – Commitments and Contingencies.

Use of Estimates

Our unaudited condensed consolidated financial statements are prepared in accordance with U.S. GAAP. The preparation of our unaudited 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 unaudited condensed consolidated financial statements and accompanying notes. The most significant estimates in our unaudited 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 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 unaudited condensed consolidated statements of operations. For financing leases, interest expense and amortization of the ROU is included in operating expenses in our unaudited condensed 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 an operating lease for our facility headquarters and financing leases for various research and development and information technology equipment.

We do not separate lease and non-lease components of our long-term leases.

Revenue Recognition

We evaluate our agreements under Accounting Standard Codification (ASC) Topic 606, Revenue from Contracts with Customers (Topic 606) 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.

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):


	Six Months Ended June 30,
	2022		2021
Common stock warrants		13,760		13,760
Common stock options and restricted stock units		3,048,636		1,295,447
Employee stock purchase plan		19,062		1,780
Total		3,081,458		1,310,987

Recent Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board (FASB) 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 condensed consolidated financial position or results of operations when such amendment is effective.

Commitments and Contingencies - Schedule of Future Minimum Payments under Non-cancelable Operating Lease and Reconciliation to Operating Lease Liability (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Leases, Operating [Abstract]
2022	$ 536
2023	404
Less: Amount representing interest	(34)
Present value of lease payments	906
Less: Current portion of operating lease liability	$ (906)	$ (980)
Long-term operating lease liability, net of current portion		$ 398

Stockholders' Equity - Summary of Stock Option Activity (Detail)	6 Months Ended
	Jun. 30, 2022 $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number of Outstanding Stock Options, Beginning Balance \| shares	1,412,550
Stock options granted \| shares	1,528,444
Number of Outstanding Stock Options, Exercised \| shares \| shares	(259)
Number of Outstanding Stock Options, Canceled/forfeited/expired \| shares	(13,537)
Number of Outstanding Stock Options, Ending Balance \| shares	2,927,198
Weighted Average Exercise Price, Beginning Balance \| $ / shares	$ 12.01
Weighted Average Exercise Price, Granted \| $ / shares	3.44
Weighted Average Exercise Price, Exercised \| $ / shares \| $ / shares	3.77
Weighted Average Exercise Price, Canceled/forfeited/expired \| $ / shares	18.17
Weighted Average Exercise Price, Ending Balance \| $ / shares	$ 7.51

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			6 Months Ended
	Aug. 08, 2022	Aug. 12, 2022	May 31, 2022	Mar. 31, 2022	Jun. 30, 2022
Subsequent Event [Line Items]
Stock options granted					1,528,444
Inducement Pool Non Qualified Option \| Common Stock [Member]
Subsequent Event [Line Items]
Stock options granted			113,400	58,400
Exercise price, granted			$ 3.48	$ 5.24
Subsequent Event [Member] \| ATM Offering Program [Member]
Subsequent Event [Line Items]
Weighted-average price per share		$ 3.38
Proceeds from issuance of common stock		$ 1.6
Subsequent Event [Member] \| Common Stock [Member] \| ATM Offering Program [Member]
Subsequent Event [Line Items]
Number of shares issued and sold		497,588
Subsequent Event [Member] \| Inducement Pool Non Qualified Option \| Common Stock [Member]
Subsequent Event [Line Items]
Stock options granted	20,600
Exercise price, granted	$ 3.70

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2022 USD ($) ft²	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)
Debt Instruments [Abstract]
Operating lease, cost		$ 200,000	$ 200,000	$ 500,000	$ 500,000
Operating lease, weighted-average remaining lease term		10 months 24 days		10 months 24 days
Operating lease, weighted-average discount rate		9.60%		9.60%
Area of office and laboratory space \| ft²	23,696
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	3.00%
Allowance for tenant improvements	$ 5,500,000
Additional allowance for tenant improvements	$ 600,000
Base rent amortized percentage	8.00%
Security deposit		$ 700,000		$ 700,000
Financing lease, term of contract		48 months		48 months
Financing lease, weighted-average remaining lease term		4 years 1 month 6 days		4 years 1 month 6 days
Financing lease, weighted-average discount rate		8.76%		8.76%

Fair Value Measurements - Additional Information (Detail) - Maximum [Member]	6 Months Ended
	Jun. 30, 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

Stockholders' Equity - Schedule of Allocation of Stock-Based Compensation for All Options and Restricted Stock Units and Stock Issued Pursuant to Our Employee Stock Purchase Plan (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 517	$ 398	$ 934	$ 758
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	131	64	238	128
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 386	$ 334	$ 696	$ 630

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, 2020	31,484	$ 11	370,210	(43)	(338,528)	(166)
Begining balance, Shares at Dec. 31, 2020		11,018,954
Net unrealized loss on investments, net of tax	(18)
Net loss	(17,547)
Ending balance at Jun. 30, 2021	40,805	$ 16	397,091	(61)	(356,070)	(171)
Ending balance, Shares at Jun. 30, 2021		16,307,370
Beginning balance at Mar. 31, 2021	49,532	$ 16	395,422	(57)	(345,679)	(170)
Begining balance, Shares at Mar. 31, 2021		16,011,385
Issuance of common stock upon exercise of stock options	1		1
Issuance of common stock upon exercise of stock options, shares		553
Issuance of common stock pursuant to employee stock purchase plan	5		5
Issuance of common stock pursuant to employee stock purchase plan, shares		1,602
Issuance of common stock from at-the-market offerings, net of offering costs	1,265		1,265
Issuance of common stock from at the market offerings, net of offering costs, shares		293,830
Stock-based compensation	398		398
Net unrealized loss on investments, net of tax	(4)			(4)
Net loss	(10,392)				(10,391)	(1)
Ending balance at Jun. 30, 2021	40,805	$ 16	397,091	(61)	(356,070)	(171)
Ending balance, Shares at Jun. 30, 2021		16,307,370
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
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
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 exercise of stock options, shares	259
Net unrealized loss on investments, net of tax	$ (547)
Net loss	(24,575)
Ending balance at Jun. 30, 2022	86,458	$ 28	484,286	(810)	(396,869)	(177)
Ending balance, Shares at Jun. 30, 2022		28,127,458
Beginning balance at Mar. 31, 2022	98,374	$ 28	483,730	(759)	(384,449)	(176)
Begining balance, Shares at Mar. 31, 2022		28,056,249
Issuance of common stock pursuant to employee stock purchase plan	5		5
Issuance of common stock pursuant to employee stock purchase plan, shares		1,958
Issuance of common stock from at-the-market offerings, net of offering costs	34		34
Issuance of common stock from at the market offerings, net of offering costs, shares		69,251
Stock-based compensation	517		517
Net unrealized loss on investments, net of tax	(51)			(51)
Net loss	(12,421)				(12,420)	(1)
Ending balance at Jun. 30, 2022	$ 86,458	$ 28	$ 484,286	$ (810)	$ (396,869)	$ (177)
Ending balance, Shares at Jun. 30, 2022		28,127,458

Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 7,455	$ 2,052
Total assets measured at fair value	87,525	107,627
Available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	80,070	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	26,720	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	44,550	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	8,800	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	7,455	2,052
Total assets measured at fair value	7,455	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	80,070	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	80,070	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	26,720	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	44,550	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	$ 8,800	$ 12,941

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Significant Accounting Policies [Line Items]
Net loss	$ (12,420)	$ (10,391)	$ (24,573)	$ (17,542)
Accumulated deficit	(396,869)		(396,869)		$ (372,296)
Cash, cash equivalents, restricted cash and available-for-sale investments	89,300		89,300
Restricted cash	$ 733		$ 733
Pangu BioPharma [Member] \| Hong Kong [Member]
Significant Accounting Policies [Line Items]
Majority-owned subsidiary percentage	98.00%		98.00%

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

Condensed Consolidated Statements of Cash Flows (Unaudited) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)
Cash flows from operating activities:
Consolidated net loss	$ (12,421)	$ (24,575)	$ (17,547)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization		144	244
Stock-based compensation	517	934	758
Amortization of premium of available-for-sale investment securities		434	106
Amortization of right-of-use assets		440	411
Gain on disposal of property and equipment		(89)
Changes in operating assets and liabilities:
Other receivables		9	1,949
Prepaid expenses and other assets		831	(405)
Accounts payable and accrued expenses		3,108	1,379
Operating lease liability		(472)	(414)
Net cash used in operating activities		(19,236)	(13,519)
Cash flows from investing activities:
Purchases of property and equipment		(96)	(113)
Purchases of available-for-sale investment securities		(11,176)	(40,024)
Maturities of available-for-sale investment securities		35,700	12,768
Proceeds from sale of property and equipment		169
Net cash provided by (used in) investing activities		24,597	(27,369)
Cash flows from financing activities:
Proceeds from issuance of common stock through option exercises		1	1
Proceeds from issuance of common stock through employee stock purchase plan		5	5
Proceeds from issuance of common stock from at-the-market offerings, net of offering costs		1,514	10,886
Proceeds from issuance of common stock from committed purchase agreement, net of offering costs			15,236
Net cash provided by financing activities		1,520	26,128
Net change in cash, cash equivalents and restricted cash		6,881	(14,760)
Cash, cash equivalents and restricted cash at beginning of period		2,336	16,952
Cash, cash equivalents and restricted cash at the end of period	9,217	9,217	2,192
Cash and cash equivalents at the end of period	8,484	8,484	2,192
Restricted cash at the end of period	733	733
Cash, cash equivalents and restricted cash at the end of period	$ 9,217	9,217	$ 2,192
Supplemental schedule of noncash investing and financing activities:
Purchases of property and equipment in accounts payable		143
Right-of-use assets obtained in exchange for lease obligation		$ 368

Stockholders' Equity

6 Months Ended

Jun. 30, 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 DemandTM Sales Agreement with JonesTrading Institutional Services LLC (JonesTrading) for an at-the-market offering program (the 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 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 Prior ATM Offering Program. During the six months ended June 30, 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 Prior ATM Offering Program. In April 2022, we terminated the Prior ATM Offering Program.

In April 2022, we entered into an Open Market Sale AgreementSM with Jefferies LLC (Jefferies) implementing an “at-the-market” offering program (the 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 ATM Offering Program. During the six months ended June 30, 2022, we sold an aggregate of 69,251 shares of common stock at a weighted-average price of $2.80 per share for gross proceeds of approximately $0.2 million under the ATM Offering Program.

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. During the six months ended June 30, 2021, we sold an aggregate of 3,000,000 shares of common stock at a weighted-average price of $5.09 per share for net proceeds of $15.2 million under the Purchase Agreement. During the six months ended June 30, 2022, there were no issuances or sales under the Purchase Agreement.

Inducement Grants

In March 2022, we adopted and our board of directors approved 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, subject to continuous employment.

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 10 new employees. In May 2022, we granted nonstatutory stock options under our Inducement Plan to purchase an aggregate of 113,400 shares of our common stock, each with an exercise price of $3.48 per share as inducement awards to four new employees.

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance was as follows:


	June 30, 2022
Common stock warrants		13,760
Common stock options and restricted stock units		3,048,636
Shares available under the 2015 equity incentive plan		961,351
Shares available under the 2022 inducement plan		128,200
Shares available under the employee stock purchase plan		819,975
		4,971,922

The following table summarizes our stock option activity under all equity incentive plans for the six months ended June 30, 2022:


	Number of Outstanding Stock Options			Weighted- Average Exercise Price
Outstanding as of December 31, 2021		1,412,550		$	12.01
Granted		1,528,444		$	3.44
Exercises		(259	)	$	3.77
Canceled/forfeited/expired		(13,537	)	$	18.17
Outstanding as of June 30, 2022		2,927,198		$	7.51

The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Expected term (in years)	6.02 – 6.06			5.50 – 6.08			6.02 – 6.08			5.50 – 6.08
Risk-free interest rate	2.8%-3.0%			1.07% – 1.09%			1.7% – 3.0%			0.6% – 1.09%
Expected volatility	84.7% – 84.9%			87.4% – 88.29%			84.7% – 86.5%			88.3% – 104.8%
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%

The following table summarizes our restricted stock unit activity under all equity incentive plans for the six months ended June 30, 2022:


	Number of Outstanding Restricted Stock Units			Weighted-Average Grant Date Fair Value
Balance as of December 31, 2021		7,500		$	4.08
Granted		116,438		$	5.13
Released		(2,500	)	$	4.13
Balance as of June 30, 2022		121,438		$	5.09

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):


	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	131	$	64	$	238	$	128
General and administrative		386		334		696		630
Total stock-based compensation expense	$	517	$	398	$	934	$	758

License and Other Agreements

6 Months Ended

Jun. 30, 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 million milestone payment in January 2021 following completion of enrollment in the Phase 1 clinical trial. Kyorin plans to join our Phase 3 clinical trial of efzofitimod in pulmonary sarcoidosis patients (EFZO-FIT™ study), and all study activity in Japan will be funded by Kyorin. 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.

During the three and six months ended June 30, 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 to September 30, 2022 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 June 30, 2022 and 2021 were $45,000 and $0.1 million, respectively. Expenses for the six months ended June 30, 2022 and 2021 were $0.1 million and $0.3 million, respectively.

Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2022

Summary of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance was as follows:


	June 30, 2022
Common stock warrants		13,760
Common stock options and restricted stock units		3,048,636
Shares available under the 2015 equity incentive plan		961,351
Shares available under the 2022 inducement plan		128,200
Shares available under the employee stock purchase plan		819,975
		4,971,922

Summary of Stock Option Activity

The following table summarizes our stock option activity under all equity incentive plans for the six months ended June 30, 2022:


	Number of Outstanding Stock Options			Weighted- Average Exercise Price
Outstanding as of December 31, 2021		1,412,550		$	12.01
Granted		1,528,444		$	3.44
Exercises		(259	)	$	3.77
Canceled/forfeited/expired		(13,537	)	$	18.17
Outstanding as of June 30, 2022		2,927,198		$	7.51

Schedule of Restricted Stock Unit Activity

The following table summarizes our restricted stock unit activity under all equity incentive plans for the six months ended June 30, 2022:


	Number of Outstanding Restricted Stock Units			Weighted-Average Grant Date Fair Value
Balance as of December 31, 2021		7,500		$	4.08
Granted		116,438		$	5.13
Released		(2,500	)	$	4.13
Balance as of June 30, 2022		121,438		$	5.09

Schedule of Allocation of Stock-Based Compensation for All Options and Restricted Stock Units and Stock Issued Pursuant 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):


	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	131	$	64	$	238	$	128
General and administrative		386		334		696		630
Total stock-based compensation expense	$	517	$	398	$	934	$	758

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:


	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Expected term (in years)	6.02 – 6.06			5.50 – 6.08			6.02 – 6.08			5.50 – 6.08
Risk-free interest rate	2.8%-3.0%			1.07% – 1.09%			1.7% – 3.0%			0.6% – 1.09%
Expected volatility	84.7% – 84.9%			87.4% – 88.29%			84.7% – 86.5%			88.3% – 104.8%
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%

Stockholders' Equity - Schedule of Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member]	6 Months Ended
	Jun. 30, 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 - 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		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	2.80%	1.07%	1.70%	0.60%
Risk-free interest rate, maximum	3.00%	1.09%	3.00%	1.09%
Expected volatility, minimum	84.70%	87.40%	84.70%	88.30%
Expected volatility, maximum	84.90%	88.29%	86.50%	104.80%
Expected dividend yield	0.00%	0.00%	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 6 months	6 years 7 days	5 years 6 months
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 21 days	6 years 29 days	6 years 29 days	6 years 29 days

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating expenses:
Research and development	$ 9,135	$ 7,655	$ 18,031	$ 12,171
General and administrative	3,449	2,790	6,931	5,476
Total operating expenses	12,584	10,445	24,962	17,647
Loss from operations	(12,584)	(10,445)	(24,962)	(17,647)
Total other income (expense), net	163	53	387	100
Consolidated net loss	(12,421)	(10,392)	(24,575)	(17,547)
Net loss attributable to noncontrolling interest in Pangu BioPharma Limited	1	1	2	5
Net loss attributable to aTyr Pharma, Inc.	$ (12,420)	$ (10,391)	$ (24,573)	$ (17,542)
Net loss per share, basic	$ (0.44)	$ (0.64)	$ (0.88)	$ (1.16)
Net loss per share, diluted	$ (0.44)	$ (0.64)	$ (0.88)	$ (1.16)
Shares used in computing net loss per share, basic	28,063,387	16,128,473	27,941,560	15,121,721
Shares used in computing net loss per share, diluted	28,063,387	16,128,473	27,941,560	15,121,721

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended			6 Months Ended		9 Months Ended	12 Months Ended
	May 31, 2022	Mar. 31, 2022	Sep. 30, 2020	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2021	Apr. 30, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Commission Rate Equal To Gross Proceeds1								3.00%	3.00%
Number of common stock shares reserved for issuance				4,971,922
Stock options granted				1,528,444
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
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			$ 20,000,000.0
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 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from Issuance of Common Stock						$ 80,600,000
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			$ 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									$ 25,000,000.0
ATM Offering Program [Member] \| Jefferies LLC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Issued, Price Per Share				$ 2.80
Proceeds from Issuance of Common Stock				$ 200,000
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								$ 65,000,000.0
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	113,400	58,400
Exercise price, granted	$ 3.48	$ 5.24
Common Stock [Member] \| Inducement Pool Non Qualified Option [Member] \| 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 [Member] \| Share-based Payment Arrangement, Tranche Two [Member]
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 [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						$ 8.00
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
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				69,251

Commitments and Contingencies - Schedule of Future Minimum Payments under Non-cancelable Financing Lease and Reconciliation to Financing Lease Liability (Detail) $ in Thousands	Jun. 30, 2022 USD ($)
Finance Lease, Liability [Abstract]
2022	$ 49
2023	99
2024	99
2025	99
2026	97
Less: Amount representing interest	(75)
Present value of lease payments	368
Less: Current portion of operating lease liability	(70)
Long-term operating lease liability, net of current portion	$ 298

Fair Value Measurements - Schedule of Available-for-sale Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	$ 80,829	$ 105,788
Gross Unrealized Losses	(759)	(213)
Market Value	80,070	105,575
Short-term Investments \| Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	26,864	36,956
Gross Unrealized Losses	(144)	(35)
Market Value	26,720	36,921
Short-term Investments \| Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	8,883	12,973
Gross Unrealized Losses	(83)	(32)
Market Value	8,800	12,941
Short-term Investments \| Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Amortized Cost	45,082	55,859
Gross Unrealized Losses	(532)	(146)
Market Value	$ 44,550	$ 55,713

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 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	85,000,000	42,500,000
Common stock, shares issued	28,127,458	27,793,035
Common stock, shares outstanding	28,127,458	27,793,035
Class X Convertible Preferred Stock [Member]
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 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 Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of June 30, 2022
Assets:
Current:
Cash equivalents	$	7,455	$	7,455	$	—	$	—
Available-for-sale investments:
Commercial paper		26,720		—		26,720		—
Corporate debt securities		44,550		—		44,550		—
Municipal bonds		8,800		—		8,800		—
Total available-for-sale investments		80,070		—		80,070		—
Total assets measured at fair value	$	87,525	$	7,455	$	80,070	$	—


			Fair Value Measurements Using
	Total		Quoted Prices in Active Markets for Identical 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 June 30, 2022 and December 31, 2021, available-for-sale investments are detailed as follows (in thousands):


		June 30, 2022
	Contractual Maturity	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Market Value
Available-for-sale investments:
Commercial paper	Within 1 year	$	26,864	$	—	$	(144	)	$	26,720
Corporate debt securities	1 to 2 years		45,082		—		(532	)		44,550
Municipal bonds	1 to 2 years		8,883		—		(83	)		8,800
		$	80,829	$	—	$	(759	)	$	80,070


		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

Subsequent Events

6 Months Ended

Jun. 30, 2022

Subsequent Events [Abstract]

Subsequent Events

6. Subsequent Events

From July 1, 2022 through August 12, 2022, we sold an aggregate of 497,588 shares of common stock at a weighted-average price of $3.38 per share through the ATM Offering Program for net proceeds of $1.6 million.

On August 8, 2022, we granted nonstatutory stock options under our Inducement Plan to purchase an aggregate of 20,600 shares of our common stock, each with an exercise price of $3.70 per share as inducement awards to four new employees.

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2022	Aug. 12, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
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		28,625,046
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 Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Consolidated net loss	$ (12,421)	$ (10,392)	$ (24,575)	$ (17,547)
Other comprehensive loss:
Change in unrealized loss on available-for-sale investments, net of tax	(51)	(4)	(547)	(18)
Comprehensive loss	(12,472)	(10,396)	(25,122)	(17,565)
Comprehensive loss attributable to noncontrolling interest in Pangu BioPharma Limited	1	1	2	5
Comprehensive loss attributable to aTyr Pharma, Inc. common stockholders	$ (12,471)	$ (10,395)	$ (25,120)	$ (17,560)

- Definition

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

- Definition

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

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+ Details

Commitments and Contingencies

6 Months Ended

Jun. 30, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

4. Commitments and Contingencies

Operating Leases


	Operating Lease
2022	$	536
2023		404
Less: Amount representing interest		(34	)
Present value of lease payments		906
Less: Current portion of operating lease liability		(906	)
Long-term operating lease liability, net of current portion	$	—

For each of the three months ended June 30, 2022 and 2021, we recorded an operating lease cost of $0.2 million. For each of the six months ended June 30, 2022 and 2021, we recorded an operating lease cost of $0.5 million. As of June 30, 2022, the weighted-average remaining lease term was 0.9 years and the weighted-average discount rate was 9.6%.

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 eight percent (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 June 30, 2022.

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. Financing lease payments for equipment received in June 2022 will start in July 2022. Future minimum payments under the non-cancelable financing lease and reconciliation to the financing lease liability as of June 30, 2022 were as follows (in thousands):


	Financing Lease
2022	$	49
2023		99
2024		99
2025		99
2026		97
Less: Amount representing interest		(75	)
Present value of lease payments		368
Less: Current portion of operating lease liability		(70	)
Long-term operating lease liability, net of current portion	$	298

As of June 30, 2022, the weighted-average remaining lease term was 4.1 years and the weighted-average discount rate was 8.76%.

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2022

Accounting Policies [Abstract]

Organization and Business

Principles of Consolidation

Unaudited Interim Financial Information

Risks and Uncertainties

Liquidity and Financial Condition

our product candidates.

Restricted Cash

Use of Estimates

Leases

Our ROU assets consist of an operating lease for our facility headquarters and financing leases for various research and development and information technology equipment.

We do not separate lease and non-lease components of our long-term leases.

Revenue Recognition

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):


	Six Months Ended June 30,
	2022		2021
Common stock warrants		13,760		13,760
Common stock options and restricted stock units		3,048,636		1,295,447
Employee stock purchase plan		19,062		1,780
Total		3,081,458		1,310,987

Recent Accounting Pronouncements

Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 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):


	Six Months Ended June 30,
	2022		2021
Common stock warrants		13,760		13,760
Common stock options and restricted stock units		3,048,636		1,295,447
Employee stock purchase plan		19,062		1,780
Total		3,081,458		1,310,987

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 8,484	$ 2,336
Available-for-sale investments	80,070	105,575
Other receivables	426	435
Prepaid expenses	4,375	5,223
Total current assets	93,355	113,569
Restricted cash	733
Property and equipment, net	558	543
Operating lease, right-of-use assets	827	1,267
Financing lease, right-of-use assets	368
Other assets	175	158
Total assets	96,016	115,537
Current liabilities:
Accounts payable	1,674	1,031
Accrued expenses	6,610	4,002
Current portion of operating lease liability	906	980
Current portion of financing lease liability	70
Total current liabilities	9,260	6,013
Long-term operating lease liability, net of current portion		398
Long-term financing lease liability, net of current portion	298
Commitments and contingencies (Note 4)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 undesignated authorized shares as of June 30, 2022 (unaudited) and December 31, 2021; Class X Convertible Preferred Stock, issued and outstanding shares - 0 as of June 30, 2022 (unaudited) and December 31, 2021
Common stock, $0.001 par value per share; 85,000,000 and 42,500,000 authorized shares as of June 30, 2022 (unaudited) and December 31, 2021, respectively; issued and outstanding shares - 28,127,458 and 27,793,035 as of June 30, 2022 (unaudited) and December 31, 2021, respectively	28	28
Additional paid-in capital	484,286	481,832
Accumulated other comprehensive loss	(810)	(263)
Accumulated deficit	(396,869)	(372,296)
Total aTyr Pharma, Inc. stockholders’ equity	86,635	109,301
Noncontrolling interest in Pangu BioPharma Limited	(177)	(175)
Total stockholders’ equity	86,458	109,126
Total liabilities and stockholders’ equity	$ 96,016	$ 115,537

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	6 Months Ended
	Jun. 30, 2022	Jun. 30, 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	3,081,458	1,310,987
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	3,048,636	1,295,447
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	19,062	1,780