Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis together with the consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K (Annual Report). The following discussion contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those expressed or implied in any forward-looking statements as a result of various factors, including those set forth under the caption “Part I, Item 1A. Risk Factors.”

Overview

We are a clinical stage biotechnology company leveraging evolutionary intelligence to translate tRNA synthetase biology into new therapies for fibrosis and inflammation. tRNA synthetases are ancient, essential proteins that have evolved novel domains that regulate diverse pathways extracellularly in humans. Our discovery platform is focused on unlocking hidden therapeutic intervention points by uncovering signaling pathways driven by our proprietary library of domains derived from all 20 tRNA synthetases.

Efzofitimod

Our lead therapeutic candidate is efzofitimod, a first-in-class biologic immunomodulator in clinical development for the treatment of interstitial lung disease (ILD), a group of immune-mediated disorders that can cause inflammation and fibrosis, or scarring, of the lungs. Efzofitimod is a tRNA synthetase derived therapy that selectively modulates activated myeloid cells through neuropilin-2 (NRP2) to resolve aberrant inflammation without immune suppression and potentially prevent the progression of fibrosis. ILDs are predominantly immune-mediated disorders that are characterized by chronic inflammation, which can lead to progressive fibrosis of the lung. There are limited treatment options for ILD and there remains a high unmet medical need. Sarcoidosis and systemic sclerosis (SSc, also known as scleroderma)-associated ILD (SSc-ILD) are two major forms of ILD. The U.S. Food and Drug Administration (FDA) has

granted efzofitimod orphan drug designations for the treatment of sarcoidosis and for the treatment of SSc, and Fast Track designations for the treatment of pulmonary sarcoidosis and for the treatment of SSc-ILD. The European Commission (EC) has granted efzofitimod orphan drug designations for the treatment of sarcoidosis and for the treatment of SSc, based on the opinion of the European Medicines Agency (EMA) Committee for Orphan Medicinal Products (COMP).

In September 2021, we announced positive results and clinical proof-of-concept from a double-blind, placebo-controlled Phase 1b/2a clinical trial in 37 patients with pulmonary sarcoidosis. The study was designed to evaluate the safety, tolerability, immunogenicity and preliminary efficacy of three doses of intravenous (IV) efzofitimod, 1.0, 3.0 and 5.0 mg/kg, in the context of a forced steroid taper. Efzofitimod was safe and well-tolerated at all doses administered with no serious drug-related adverse events or signal of immunogenicity. Additionally, the study demonstrated consistent dose response for efzofitimod on key efficacy endpoints and improvements compared to placebo, including measures of steroid reduction, lung function, pulmonary sarcoidosis symptom measures and inflammatory biomarkers. These data were subsequently presented at the American Thoracic Society (ATS) International Conference and published in the peer-reviewed journal CHEST during 2022.

In February 2022, we met with the FDA in an end-of-Phase 2 meeting to discuss our plans for subsequent clinical development and path to registration for efzofitimod for pulmonary sarcoidosis. Subsequently, we initiated a global pivotal Phase 3 randomized, double-blind, placebo-controlled clinical trial to evaluate the efficacy and safety of efzofitimod in patients with pulmonary sarcoidosis (the EFZO-FIT study). The EFZO-FIT study is a 52-week study consisting of three parallel cohorts randomized equally to either 3.0 mg/kg or 5.0 mg/kg of efzofitimod or placebo dosed intravenously once a month for a total of 12 doses. The study is currently enrolling and intends to enroll up to 264 subjects with pulmonary sarcoidosis at multiple centers in the United States, Europe, Brazil, and Japan. The study design incorporates a forced steroid taper. The objective of the study is to evaluate the efficacy and safety of efzofitimod in patients with pulmonary sarcoidosis. The primary endpoint of the study is steroid reduction. Secondary endpoints include measures of lung function assessed by forced vital capacity (FVC) and health-related quality of life assessments and questionnaires (KSQ lung score). In September 2022, we dosed the first patient in this study. Additionally, during 2023, we had a data and safety monitoring board (DSMB) review of our EFZO-FIT study. The DSMB concluded that the study could continue unmodified. We expect to complete enrollment in the study in the second quarter of 2024.

In February 2024, we announced an Individual Patient Expanded Access Program (EAP). The Individual Patient EAP has been initiated based on blinded EFZO-FITTM study investigator and patient participant feedback. The program is designed to allow access for patients who complete the Phase 3 EFZO-FITTM study and wish to receive treatment with efzofitimod outside of the clinical trial. The administration of efzofitimod as part of the Individual Patient EAP will occur independent of the EFZO-FIT study protocol, and we, principal investigators and patients will remain blinded to the treatment that occurred as part of the EFZO-FIT study. As this Individual Patient EAP will occur independent of the EFZO-FIT study, this program is not an open-label extension (OLE) and no long-term data will be collected by us.

Based on the results of the Phase 1b/2a clinical trial, we believe efzofitimod has potential applications in the treatment of other ILDs, such as chronic hypersensitivity pneumonitis (CHP) and connective tissue disease related ILD (CTD-ILD), including SSc-ILD and rheumatoid arthritis-associated ILD. As such, we designed a focused Phase 2 proof-of-concept clinical trial of efzofitimod (the EFZO-CONNECT study) in patients with SSc-ILD. The EFZO-CONNECT study is a randomized, double-blind placebo-controlled proof-of-concept study to evaluate the efficacy, safety and tolerability of efzofitimod in patients with SSc-ILD. This is a 28-week study with three parallel cohorts randomized 2:2:1 to either 270 mg or 450 mg of efzofitimod or placebo dosed intravenously monthly for a total of six doses. The study intends to enroll up to 25 patients at multiple centers in the United States. The objective of the study is to evaluate the efficacy of multiple doses of IV efzofitimod on pulmonary, cutaneous and systemic manifestations in patients with SSc-ILD. The primary endpoint is reduction in FVC. Secondary endpoints include certain measures regarding safety and tolerability. The study was initiated in the third quarter of 2023, and in October 2023, we dosed the first patient in this study.

In January 2020, we entered into a collaboration and license agreement (Kyorin Agreement) with Kyorin Pharmaceutical Co., Ltd. (Kyorin) for the development and commercialization of efzofitimod for the treatment of ILD in Japan. Under the Kyorin Agreement, Kyorin received an exclusive right to develop and commercialize efzofitimod in Japan for all forms of ILD, and is obligated to fund all research, development, regulatory, marketing and commercialization activities in Japan. In 2020, Kyorin conducted and funded a Phase 1 clinical trial of efzofitimod (known as KRP-R120 in Japan). The Phase 1 clinical trial was a placebo-controlled clinical trial to evaluate the safety, pharmacokinetics (PK) and immunogenicity of efzofitimod in 32 healthy Japanese male volunteers. Efzofitimod was observed to be generally well-tolerated with no drug-related serious adverse events, and PK findings were consistent with previous studies of efzofitimod. Kyorin is also participating in the EFZO-FIT study as the local sponsor in Japan. In February 2023, Kyorin dosed the first patient in Japan in the EFZO-FIT study which triggered a $10.0 million milestone payment to us. To date, the Kyorin Agreement has generated $20.0 million in upfront and milestone payments to us and we are eligible to receive up to an additional $155.0 million in the aggregate upon achievement of certain development, regulatory and sales milestones, as well as tiered royalties on any net sales in Japan.

Discovery Platform

Using efzofitimod as a model, we have developed a process to advance novel tRNA synthetase domains from a concept to therapeutic candidate. This process leverages our early discovery work as well as current scientific understanding of tRNA synthetase evolution, protein structure, gene splicing and tissue-specific regulation to identify potentially active protein domains. Screening approaches are employed to identify target cells and extracellular receptors for these tRNA synthetase-derived proteins. These cellular systems can then be used in mechanism-of-action studies to elucidate the role these proteins play in cellular responses and their potential therapeutic utility. We are working to identify new tRNA synthetase based drug candidates through our internal discovery efforts and external collaboration efforts.

Impact of Geopolitical and Macroeconomic Conditions

Global economic and business activities continue to face widespread macroeconomic uncertainties, including global geopolitical tension, armed conflicts, labor shortages, inflation and monetary supply shifts, liquidity concerns at, and failures of, banks and other financial institutions or other disruptions in the banking system or financing markets, higher interest rates and financial and credit market fluctuations, volatility in the capital markets and recession risks, which has resulted in further volatility in the U.S. and global financial markets and which has led to, and may continue to lead to, additional disruptions to trade, commerce, pricing stability, credit availability and supply chain continuity globally. The ultimate long-term impact of these evolving geopolitical and macroeconomic conditions on our business is uncertain, although we continue to actively monitor the impact of these factors on our results of operations, financial condition and cash flows. The extent of the impact of these factors on our operational and financial performance, including our ability to execute our business strategies and initiatives in the expected timeframe, will depend on future developments, which are uncertain and cannot be predicted; however, any continued or renewed disruption resulting from these factors could negatively impact our business.

Liquidity and Capital Resources

We have incurred losses and negative cash flows from operations since our inception. As of December 31, 2023, we had an accumulated deficit of $468.0 million, and we expect to continue to incur net losses for the foreseeable future. As of December 31, 2023, we had cash, cash equivalents, restricted cash and available-for-sale investments of $101.7 million. We believe that our current cash, cash equivalents, restricted cash and available-for-sale investments, 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 date of this Annual Report. In addition to the factors discussed under “Material Cash Requirements,” our ability to fund our longer-term operating needs will depend on our ability to raise additional funding through equity or debt offerings, grant funding, collaborations, strategic partnerships and/or licensing arrangements, and other factors, including those discussed in Part I, Item 1A. “Risk Factors - Risks related to our financial condition and need for additional capital—We will need to raise additional capital or enter into strategic partnering relationships to fund our operations.”

Sources of Cash

From our inception through December 31, 2023, we have financed our operations primarily through the sale of equity securities and convertible debt, venture debt, term loans and through license and collaboration agreement revenues.

Public Offerings

In February 2023, we completed an underwritten follow-on public offering of 23,125,000 shares of our common stock, including the partial exercise of the underwriters’ option to purchase additional shares, at a price to the public of $2.25 per share. The total net proceeds from the offering were approximately $48.1 million, after deducting underwriting discounts, commissions and offering expenses payable by us.

In September 2021, we completed an underwritten follow-on public offering of 10,781,250 shares of our common stock, including the full exercise of the underwriters’ option to purchase additional shares, at a price to the public of $8.00 per share. The total net proceeds from the offering were approximately $80.6 million, after deducting underwriting discounts, commissions and offering expenses payable by us.

At-the-Market Offering Programs

In April 2022, we entered into an Open Market Sale AgreementSM with Jefferies LLC (Jefferies) (the Jefferies ATM Offering Program), pursuant to which we may offer and sell, from time to time and at our option, up to an aggregate of $65.0 million of shares of our common stock through Jefferies, acting as sales agent. Jefferies is entitled to a fixed commission rate of up to 3.0% of the gross sales proceeds of shares sold under the Jefferies ATM Offering Program. During the year ended December 31, 2023, we sold an aggregate of 10,530,795 shares of common stock at a weighted-average price of $1.82 per share for net proceeds of approximately $18.4 million under the Jefferies ATM Offering Program. Additionally, from January 1, 2024 through March 13, 2024, we sold an aggregate of 4,441,509 shares of common stock at a weighted-average price of $1.75 per share for net proceeds of approximately $7.6 million under the Jefferies ATM Offering Program.

In May 2019, we entered into a sales agreement with H.C. Wainwright & Co., LLC (Wainwright) for an ATM Offering Program (the Wainwright ATM Offering Program) under which we could offer and sell shares of our common stock having an aggregate offering price of up to $10.0 million. In November 2020, we amended our sales agreement with Wainwright to increase the amount of the ATM Offering Program to $20.0 million. Wainwright was entitled to a commission at a fixed commission rate equal to 3% of the gross proceeds. In March 2021, the ATM Offering Program with Wainwright automatically terminated upon the issuance and sale of all of the shares having an aggregate offering price of $20.0 million. Prior to the termination of the sales agreement with Wainwright, in 2021, we sold an aggregate of 1,988,254 shares of common stock at an average price of $4.99 per share for net proceeds of $9.6 million.

Purchase Agreement

In September 2020, we entered into a common stock purchase agreement (the Purchase Agreement) with Aspire Capital Fund, LLC (Aspire Capital), which provided that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital was 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. In 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. There were no issuances or sales under the Purchase Agreement during the years ended December 31, 2023 and December 31, 2022, respectively, and this agreement was terminated on March 11, 2023.

Kyorin Agreement Milestone Payments

On February 6, 2023, we announced that our partner Kyorin dosed the first patient in Japan in the EFZO-FIT study, which triggered a $10.0 million milestone payment by Kyorin to us pursuant to the Kyorin Agreement. We recorded this $10.0 million milestone as revenue in December 2022 and received the cash in February 2023. Kyorin is our partner for the development and commercialization of efzofitimod for ILD in Japan. Under the Kyorin Agreement, we have generated $20.0 million in upfront and milestone payments to date and are eligible to receive up to an additional $155.0 million in the aggregate upon the achievement of certain development, regulatory and sales milestones, as well as tiered royalties on any net sales in Japan. Kyorin has the exclusive rights to develop and commercialize efzofitimod in Japan for all forms of ILD.

Cash Flows

The following table sets forth a summary of the net cash flow activity for each of the periods indicated (in thousands):

Years Ended December 31,

Net cash provided by (used in):

Operating activities. Net cash used in operating activities was $33.2 million, $41.9 million and $33.1 million for the years ended December 31, 2023, 2022 and 2021, respectively. The net cash used in each period is primarily due to the advancement of efzofitimod into later stage clinical trials and additional manufacturing campaigns to support those trials and potential future clinical trials. Net cash used in operating activities decreased during the year ended December 31, 2023 as we received a $10.0 million milestone payment from the Kyorin Agreement. We expect cash used in operating activities to increase as we advance our clinical and manufacturing efforts toward possible commercialization of efzofitimod.

Investing activities. Net cash (used in) provided by investing activities for the years ended December 31, 2023, 2022 and 2021 was $(20.1) million, $47.2 million and $(91.6) million, respectively. The fluctuation in net cash provided by or used in investing activities resulted primarily from the timing differences in investment purchases, sales and maturities, and the fluctuation of our portfolio mix between cash equivalents and investment holdings. The average term to maturity in our investment portfolio as of December 31, 2023 was less than two years. Net cash used for December 31, 2023 included $4.2 million purchases of property and equipment primarily for tenant improvements associated with our corporate headquarters facility lease.

Financing activities. Net cash provided by financing activities for the year ended December 31, 2023 was $66.2 million and consisted primarily of $48.1 million in proceeds from an underwritten follow-on public offering, net of offering costs, and $18.4 million proceeds from our Jefferies ATM Offering Program, net of issuance costs. Net cash provided by financing activities for the year ended December 31, 2022 was primarily due to cash proceeds from our ATM offering programs, net of issuance costs. Net cash provided by financing activities for the year ended December 31, 2021 was $110.0 million and consisted primarily of $80.6 million in proceeds from an underwritten follow-on public offering, net of offering costs, $15.2 million in proceeds from the issuance of common stock through a common stock purchase agreement, net of offering costs, and $14.1 million proceeds from our ATM offering programs, net of issuance costs.

Material Cash Requirements

To date, we have not generated any revenues from product sales. We expect our expenses to increase in connection with our ongoing activities, particularly as we continue to advance efzofitimod in clinical development, manufacturing and technology transfer activities, continue our research and development activities with respect to other potential therapies based on tRNA synthetase biology and seek marketing approval for product candidates that we may develop. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. We currently have no sales or marketing capabilities and would need to expand our organization to support these activities. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. Our forecast of the period of time through which our financial resources will be adequate to support our operations is a forward-looking statement that involves risks and uncertainties, and actual results could vary materially.

Our future capital requirements are difficult to forecast and will depend on many factors. Refer to Part I, Item 1A, "Risk Factors - Risks related to our financial condition and need for additional capital—We will need to raise additional capital or enter into strategic partnering relationships to fund our operations.” for a discussion of these factors.

Until such time, if ever, as we can generate substantial product revenues, we expect to finance our cash needs through a combination of 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. To the extent we raise additional capital through the sale of equity, the ownership interest of our stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our common stockholders. If we raise additional funds through collaborations, strategic partnerships or licensing arrangements with third parties, we may have to relinquish valuable rights to our product candidates, our other technologies, future revenue streams or research programs or grant licenses on terms that may not be favorable to us. The incurrence of additional indebtedness would increase our fixed payment obligations and may require us to agree to certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. We may be unable to raise additional funds on acceptable terms or at all. If the equity and credit markets deteriorate, it may make any necessary debt or equity financing more difficult, more costly and more dilutive. If we are unable to raise additional funds, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market our product candidates even if we would otherwise prefer to develop and market such product candidates ourselves.

As of December 31, 2023, our material cash requirements from known contractual and other obligations consisted primarily of (i) operating leases for our corporate headquarters and laboratory space, and (ii) our master financing lease agreement for various research and development and informational technology equipment.

Corporate Headquarters Facility Lease

In May 2022, we entered into a lease (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) commenced on March 20, 2023 (the Lease Commencement Date) and will 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 (as that term is defined in the Lease). 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 up to $5.3 million for tenant improvements of which as of December 31, 2023, we received $5.0 million from the Landlord, and we received the remaining $0.3 million in February 2024. We provided a $0.7 million security deposit in the form of a letter of credit which is included in restricted cash as of December 31, 2023. During the second quarter of 2023, additional common area amenities were completed by the Landlord which provided us with access to approximately 1,500 additional rentable square feet. As a result, our base rent increased for this additional rentable square feet at the same monthly base rent per rentable square foot as contemplated in the Lease.

Financing Lease

In April 2022, we entered into a financing lease to lease various research and development and information technology equipment over a 48-month term. Financing lease liabilities total $1.9 million as of December 31, 2023. Additionally, we provided $2.7 million in cash collateral for the financing lease, and this amount is included in restricted cash as of December 31, 2023.

We did not have any off-balance sheet arrangements as of December 31, 2023.

Financial Operations Overview

Organization and Business; Principles of Consolidation

We conduct substantially all of our activities through aTyr Pharma, Inc., a Delaware corporation, at our facility in San Diego, California. aTyr Pharma, Inc. was incorporated in the State of Delaware in September 2005. The consolidated financial statements include our accounts and our 98% majority-owned subsidiary in Hong Kong, Pangu BioPharma, as of December 31, 2023. All intercompany transactions and balances are eliminated in consolidation.

Revenue Recognition

In January 2020, we entered into the Kyorin Agreement with Kyorin for the development and commercialization of efzofitimod for the treatment of ILD in Japan. Under the Kyorin Agreement, Kyorin received an exclusive right to develop and commercialize efzofitimod in Japan for all forms of ILD, and Kyorin is obligated to fund all research, development, regulatory, marketing and commercialization activities in Japan. The Phase 1 clinical trial, which was conducted and funded by Kyorin, was a placebo-controlled clinical trial to evaluate the safety, PK and immunogenicity of efzofitimod in 32 healthy Japanese male volunteers. Efzofitimod was observed to be generally well-tolerated with no drug-related serious adverse events and PK findings were consistent with previous studies of efzofitimod. Kyorin is also participating in the EFZO-FIT study as the local sponsor in Japan. In February 2023, Kyorin dosed the first patient in Japan in the EFZO-FIT study. This achievement triggered a $10.0 million milestone payment by Kyorin to us pursuant to the Kyorin Agreement. This milestone was recorded as revenue during the year ended December 31, 2022, and the payment was received during the year ended December 31, 2023. Under the Kyorin Agreement, we have generated $20.0 million in upfront and milestone payments to date and are eligible to receive up to an additional $155.0 million in the aggregate upon the achievement of certain development, regulatory and sales milestones, as well as tiered royalties on any net sales in Japan. During the year ended December 31, 2023, we recognized $0.4 million in collaboration revenue from Kyorin for drug product material sold to Kyorin for the Japan portion of the EFZO-FIT study.

Research and Development Expenses

To date, our research and development expenses have been related primarily to the development of, and clinical trials for, our product candidates, and to research efforts targeting the potential therapeutic application of other tRNA synthetase-based immunomodulators. These expenses consist primarily of:

•

salaries and employee-related expenses, including stock-based compensation and benefits for personnel in research and product development functions;

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costs associated with conducting our preclinical, development and regulatory activities, including fees paid to third-party professional consultants, service providers and our scientific, therapeutic and clinical advisory board;

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costs to acquire, develop and manufacture preclinical study and clinical trial materials;

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costs incurred under clinical trial agreements with CROs and investigative sites;

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costs for laboratory supplies; and

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allocated facilities, depreciation and other allocable expenses.

Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. We expect that the levels of our research and development expenses will continue to increase in future years and will consist primarily of costs related to our clinical development and manufacturing of efzofitimod for patients with pulmonary sarcoidosis and SSc-ILD, and other potential therapeutics based on tRNA synthetase biology.

At this time, due to the inherently unpredictable nature of preclinical and clinical development and given the early stage of our programs, we are unable to estimate with any certainty the costs we will incur or the timelines we will require in the continued development of our product candidates. Clinical and preclinical development timelines, the probability of success and development

costs can differ materially from expectations. We anticipate that we will make determinations as to which product candidates to pursue and how much funding to direct to each product candidate on an ongoing basis in response to the results of ongoing and future preclinical studies and clinical trials, regulatory developments and our ongoing assessments as to each product candidate’s commercial potential. In addition, we cannot forecast which programs or product candidates may be subject to future collaborations, when such arrangements will be secured, if at all, and to what degree such arrangements would affect our development plans and capital requirements.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries and related costs for employees in executive, finance and administration, corporate development and administrative support functions, including stock-based compensation expenses and benefits. Other significant general and administrative expenses include accounting, legal services, expenses associated with applying for and maintaining patents, cost of insurance, cost of various consultants, occupancy costs, information systems costs and depreciation.

Critical Accounting Policies and Significant Judgments and Estimates

Our management’s discussion and analysis of financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States. The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements, as well as the reported expenses during the reporting periods. We monitor and analyze these items for changes in facts and circumstances, and material changes in these estimates could occur in the future. We base our estimates on our historical experience and on various other factors we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Changes in estimates are reflected in reported results for the period in which they become known. Actual results may differ materially from these estimates under different assumptions or conditions.

We discuss our accounting policies and assumptions that involve a higher degree of judgment and complexity within Note 2 to our audited consolidated financial statements appearing elsewhere in this Annual Report. We believe that our accounting policies related to research and development expense accruals involve the most significant estimation and judgment in accounting for our reported consolidated financial results.

Research and Development Expense Accruals

As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued expenses. This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date in our consolidated financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with the service providers and make adjustments if necessary. Examples of estimated accrued research and development expenses include fees paid to investigative sites and CROs in connection with clinical trials; service providers in connection with preclinical development activities; and service providers related to product manufacturing, development and distribution of clinical supplies.

We currently rely on third parties for the clinical development of our product candidates and the manufacture of our product candidates to support our ongoing and future clinical trials. We pay these third parties, including consultants, CROs, CDMOs and other service providers, pursuant to contractual arrangements, which may include provisions for time and materials-based payments, project-based fees and milestone payments. We base our accrual for these expenses on our estimates of the services received and efforts expended pursuant to our contractual arrangements. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our service providers will exceed the level of services provided and result in a prepayment of the clinical expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical milestones. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust our accrual or prepaid expenses accordingly.

Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differs from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period. To date, there have been no material differences between our estimates and the amounts actually incurred.

Results of Operations

Comparison of the Years Ended December 31, 2023 and 2022

In this section, we discuss the results of our operations for the year ended December 31, 2023, compared to the year ended December 31, 2022. For a discussion of the year ended December 31, 2022 compared to the year ended December 31, 2021, please refer to our Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 14, 2023.

The following table summarizes our results of operations for the years ended December 31, 2023 and 2022 (in thousands):

Years Ended December 31, Increase /

License and collaboration agreement revenues $ 353 $ 10,386 $ (10,033 )

License and collaboration agreement revenues. Revenues of $0.4 million for the year ended December 31, 2023 consisted of drug product material sold to Kyorin for the Japan portion of the EFZO-FIT study while revenues of $10.4 million for the year ended December 31, 2022 consisted primarily of the $10.0 million development milestone earned under the Kyorin Agreement as Kyorin dosed the first patient in the Japan portion of the EFZO-FIT study.

Research and development expenses. Research and development expenses were $42.3 million and $42.8 million for the years ended December 31, 2023 and 2022, respectively. The decrease of $0.5 million was due primarily to a decrease of $3.8 million in manufacturing costs due to the timing of the associated manufacturing activities conducted, a reduction of $1.9 million in earlier stage discovery research and development costs as well a reduction of $0.7 million in personnel costs. The reduction in personnel related expenses was primarily due to the recognition of the ERC benefit made available under the CARES Act as discussed under Note 2 - “Summary of Significant Accounting Policies” of our consolidated financial statements included in this Annual Report. These decreases were partially offset by an increase of $5.9 million in clinical trial costs for the EFZO-FIT and EFZO-CONNECT studies as those studies progressed during the year ended December 31, 2023. We expect research and development expenses to increase as we advance our clinical and manufacturing efforts toward possible commercialization of efzofitimod.

General and administrative expenses. General and administrative expenses were $13.0 million and $14.0 million for the years ended December 31, 2023 and 2022, respectively. The decrease of $1.0 million was due primarily to a decrease of $0.8 million in personnel related expense. The reduction in personnel related expenses was primarily due to the recognition of the ERC benefit made available under the CARES Act as discussed under Note 2 - “Summary of Significant Accounting Policies” of our consolidated financial statements included in this Annual Report.

Other income (expense), net. Other income (expense), net was $4.5 million and $1.1 million for years ended December 31, 2023 and 2022, respectively. The increase was primarily a result of interest earned on higher cash, cash equivalents, restricted cash and available-for-sale investments balances during the year ended December 31, 2023 as compared to the prior year, and increased interest rates.

Recent Accounting Pronouncements

For discussion of recently issued accounting pronouncements, refer to the Section titled “Recent Accounting Pronouncements” within Note 2 of our consolidated financial statements included in this Annual Report.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Not Applicable.

Item 8. Financial Statements and Supplementary Data.

Report of Independent Registered Public Accounting Firm

To the Stockholders and Board of Directors of aTyr Pharma, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of aTyr Pharma, Inc. (the Company) as of December 31, 2023 and 2022, the related consolidated statements of operations, comprehensive loss, stockholders’ equity and cash flows for each of the three years in the period ended December 31, 2023, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2023, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Accrued clinical and manufacturing costs

/s/ Ernst & Young LLP

We have served as the Company’s auditor since 2008.

San Diego, California

March 14, 2024

aTyr Pharma, Inc.

Consolidated Balance Sheets

(in thousands, except share and per share data)

December 31, December 31,

Assets

Current assets:

Operating lease, right-of-use assets 6,727 7,250

Financing lease, right-of-use assets 1,788 1,248

Liabilities and Stockholders’ Equity

Current liabilities:

Current portion of operating lease liability 831 630

Current portion of financing lease liability 497 264

Long-term operating lease liability, net of current portion 12,339 9,633

Long-term financing lease liability, net of current portion 1,428 1,007

Commitments and contingencies (Note 6)

Stockholders’ equity:

Accumulated other comprehensive loss (74 ) (433 )

Total aTyr Pharma, Inc. stockholders’ equity 90,658 71,464

Noncontrolling interest in Pangu BioPharma Limited (188 ) (180 )

Total liabilities and stockholders’ equity $ 120,653 $ 95,786

See accompanying notes.

aTyr Pharma, Inc.

Consolidated Statements of Operations

(in thousands, except share and per share data)

Years Ended December 31,

Revenues:

License and collaboration agreement revenues $ 353 $ 10,386 $ —

Operating expenses:

Net loss attributable to aTyr Pharma, Inc. $ (50,389 ) $ (45,338 ) $ (33,768 )

Net loss per share, basic and diluted $ (0.94 ) $ (1.60 ) $ (1.77 )

See accompanying notes.

aTyr Pharma, Inc.

Consolidated Statements of Comprehensive Loss

(in thousands)

Years Ended December 31,

Other comprehensive loss:

See accompanying notes.

aTyr Pharma, Inc.

Consolidated Statements of Stockholders’ Equity

(in thousands, except share data)

Shares Amount Capital Gain/(Loss) Deficit Interest Equity

Issuance of common stock upon exercise of stock options 10,751 — 62 — — — 62

Stock-based compensation — — 1,614 — — — 1,614

Net unrealized loss on investments, net of tax — — — (220 ) — — (220 )

Issuance of common stock upon exercise of stock options 259 — 1 — — — 1

Stock-based compensation — — 2,154 — — — 2,154

Net unrealized loss on investments, net of tax — — — (170 ) — — (170 )

Stock-based compensation — — 2,600 — — — 2,600

Net unrealized gain on investments, net of tax — — — 359 — — 359

See accompanying notes.

aTyr Pharma, Inc.

Consolidated Statements of Cash Flows

(in thousands)

Years Ended December 31,

Cash flows from operating activities:

Adjustments to reconcile net loss to net cash used in operating activities:

(Gain) loss on disposal of property and equipment (6 ) (92 ) 6

Changes in operating assets and liabilities:

Accounts payable and accrued expenses 3,262 6,741 47

Cash flows from investing activities:

Purchases of property and equipment (4,215 ) (1,641 ) (192 )

Proceeds from sale of property and equipment 15 179 50

Net cash (used in) provided by investing activities (20,127 ) 47,245 (91,566 )

Cash flows from financing activities:

Proceeds from issuance of common stock through option exercises — 1 62

Principal paid on finance lease liabilities (394 ) (66 ) —

Net change in cash, cash equivalents and restricted cash 12,882 10,810 (14,616 )

Cash and cash equivalents at the end of period $ 22,544 $ 9,981 $ 2,336

Restricted cash at the end of period 3,484 3,165 —

Supplemental disclosure of cash flow information:

Interest paid $ 172 $ 54 $ —

Purchases of property and equipment in accounts payable $ 51 $ 1,194 $ —

See accompanying notes.

aTyr Pharma, Inc.

Notes to Consolidated Financial Statements

1. Organization, Business and Basis of Presentation

Organization and Business

We were incorporated in the state of Delaware on September 8, 2005. We are a clinical stage biotechnology company leveraging evolutionary intelligence to translate tRNA synthetase biology into new therapies for fibrosis and inflammation. tRNA synthetases are ancient, essential proteins that have evolved novel domains that regulate diverse pathways extracellularly in humans. Our discovery platform is focused on unlocking hidden therapeutic intervention points by uncovering signaling pathways driven by our proprietary library of domains derived from all 20 tRNA synthetases.

Principles of Consolidation

Our consolidated financial statements include our accounts and our 98% majority-owned subsidiary in Hong Kong, Pangu BioPharma Limited (Pangu BioPharma). All intercompany transactions and balances are eliminated in consolidation.

Liquidity and Financial Condition

We have incurred losses and negative cash flows from operations since our inception. As of December 31, 2023, we had an accumulated deficit of $468.0 million and we expect to continue to incur net losses for the foreseeable future. As of December 31, 2023, our cash, cash equivalents, available-for-sale investments and restricted cash were $101.7 million. We currently have an “at-the-market” offering program (the Jefferies ATM Offering Program) through an Open Market Sale AgreementSM with Jefferies LLC (Jefferies). During the year ended December 31, 2023, we sold an aggregate of 10,530,795 shares of common stock at a weighted-average price of $1.82 per share for net proceeds of approximately $18.4 million under the Jefferies ATM Offering Program. Additionally, from January 1, 2024 through March 13, 2024, we sold an aggregate of 4,441,509 shares of common stock at a weighted-average price of $1.75 per share for net proceeds of approximately $7.6 million under the Jefferies ATM Offering Program. We believe that our current cash, cash equivalents, available-for-sale investments and restricted cash, will be sufficient to meet our anticipated cash requirements for a period of at least one year from the date of this Annual Report.

We do not expect to generate any revenues from product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our product candidates, which we expect will take a number of years at a minimum. If we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Accordingly, we will need to raise substantial additional capital to fund our operations. The amount and timing of our future funding requirements will depend on many factors, including the pace and results of our preclinical and clinical development efforts and the timing and nature of the regulatory approval process for our product candidates. We anticipate that we will seek to fund our operations through equity offerings, grant funding, collaborations, strategic partnerships and/or licensing arrangements, and when we are closer to commercialization of our product candidates potentially through debt financings. However, we may be unable to raise additional capital or enter into such arrangements when needed on favorable terms or at all. Our failure to raise capital or enter into such arrangements when needed would have a negative impact on our financial condition and ability to develop our product candidates.

Restricted Cash

As of December 31, 2023, restricted cash was approximately $3.5 million, which was held as a security deposit in conjunction with our corporate headquarter facility lease and financing leases as discussed further in Note 6 - Commitments and Contingencies.

Use of Estimates

Our consolidated financial statements are prepared in accordance with generally accepted accounting principles (GAAP). The preparation of our consolidated financial statements requires us to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure for these items in our consolidated financial statements and accompanying notes. The most significant estimates in our consolidated financial statements relate to the fair value of equity issuances and awards, and clinical trial and research and development expenses. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ materially from these estimates and assumptions.

Segment Reporting

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. We view our operations and manage our business in one operating segment

2. Summary of Significant Accounting Policies

Cash and Cash Equivalents and Restricted Cash

Cash, cash equivalents and restricted cash consist of checking, money market and highly liquid investments that are readily convertible to cash and that have an original maturity of three months or less from date of purchase. The carrying amounts approximate fair value due to the short maturities of these instruments.

Employee Retention Credit

On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was signed into law providing numerous tax incentives and other stimulus measures, including an employee retention credit (ERC), which is a refundable tax credit against certain employment taxes. The Taxpayer Certainty and Disaster Tax Relief Act of 2020 and the American Rescue Plan Act of 2021 extended and expanded the availability of the ERC.

As a result of the foregoing legislation, we determined that we are eligible to claim an ERC benefit equal to 50% of qualified wages that we paid to our employees between March 17, 2020 and December 31, 2020, and 70% of the qualified wages that we paid to our employees between January 1, 2021 and September 30, 2021. Qualified wages are limited to $10,000 per employee for March 17, 2020 through December 31, 2020, and $10,000 per employee per calendar quarter from January 1, 2021 through September 30, 2021. Our credit was primarily derived from qualified wages during January 1, 2021 through September 30, 2021. To determine eligibility for January 1, 2021 through September 30, 2021, we compared gross receipts for each calendar quarter in 2021 to the corresponding calendar quarter in 2019 and determined that we had met the requirement for a decline in gross receipts.

Accounting Standards Codification (ASC) Topic 105, Generally Accepted Accounting Principles describes the decision-making framework when no guidance exists in U.S. GAAP for a particular transaction. Specifically, ASC 105-10-05-2 instructs companies to look for guidance for a similar transaction within U.S. GAAP and apply that guidance by analogy. We accounted for the ERC by analogy to International Accounting Standards (IAS) 20, Accounting for Government Grants and Disclosure of Government Assistance, of International Financial Reporting Standards (IFRS). Under an IAS 20 analogy, a business entity would recognize the credit on a systematic basis over the periods in which the entity recognizes the payroll expenses for which the ERC is intended to compensate when there is reasonable assurance that the entity will comply with any conditions attached to the ERC and the ERC will be received.

During the year ended December 31, 2023, we amended certain payroll tax filings and applied for a refund of $1.2 million of ERC benefits. The refund was recorded within the other receivables in our consolidated balance sheet, and as a $0.8 million reduction of research and development expenses and a $0.4 million reduction of general and administrative expenses in our consolidated statements of operations for the year ended December 31, 2023.

Allowance of Credit Losses

For available-for-sale securities in an unrealized loss position, we first assess whether we intend to sell, or if it is more likely than not that we will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through earnings. For available-for-sale securities that do not meet the aforementioned criteria, we evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the severity of the impairment, any changes in interest rates, market conditions, changes to the underlying credit ratings and forecasted recovery, among other factors. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded in interest income through an allowance account. Any impairment that has not been recorded through an allowance for credit losses is included in other comprehensive income (loss) on the consolidated statements of operations and comprehensive loss.

We elected the practical expedient to exclude the applicable accrued interest from both the fair value and amortized costs basis of our available-for-sale securities for purposes of identifying and measuring an impairment. Accrued interest receivable on available-for-sale securities is recorded within other receivables on our consolidated balance sheets. Our accounting policy is to not measure an allowance for credit loss for accrued interest receivable and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which we consider to be in the period in which we determine the accrued interest will not be collected by us.

Concentration of Credit Risk

Financial instruments that potentially subject us to significant concentration of credit risk consist primarily of cash, cash equivalents, restricted cash and investment securities. We have established guidelines regarding diversification of investments and their maturities, which are designed to maintain principal and maximize liquidity. We maintain deposits in federally insured financial institutions in excess of federally insured limits. We have not experienced any losses in such accounts and we believe that we are not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.

Property and Equipment

Property and equipment are stated at cost and depreciated on a straight-line basis over the estimated useful life of the related assets (generally three to seven years). Leasehold improvements are stated at cost and amortized on a straight-line basis over the lesser of the remaining term of the related lease or the estimated useful life of the leasehold improvements. Repairs and maintenance costs are charged to expense as incurred.

Impairment of Long-Lived Assets

Long-lived assets consist primarily of property and equipment and right-of-use assets (ROU) associated with our operating and financing leases. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. While our current and historical operating losses are indicators of impairment, we believe that future cash flows to be received support the carrying value of our long-lived assets and, accordingly, have not recognized any impairment losses since inception.

Accrued Expenses

Accrued expenses include salaries, wages, benefits costs, consulting fees, legal and research and development costs. We have entered into contractual arrangements related to our clinical studies with clinical research organizations (CROs) and contracted development and manufacturing organizations (CDMOs) and recognize expense based on work completed and efforts expended pursuant to our contractual arrangements. We make estimates of our accrued CRO costs as of each balance sheet date based on facts and circumstances known at the time and include total trial management costs, sites activated, patients enrolled and number of patient visits. We estimate the time period over which services will be performed and the level of effort to be expended in each period. There may be instances in which payments made to our service providers including CROs and CDMOs, will temporarily exceed the level of services provided and result in a prepayment of the expense. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual or prepaid expense balance accordingly. Historically, our estimated accrued liabilities have materially approximated actual expenses incurred.

Leases

We determine if an arrangement is a lease at inception. Short-term leases with an initial term of 12 months or less are not recorded on our balance sheet. For long-term leases with an initial term of greater than 12 months, we recognize a right-of-use asset (ROU) and a lease liability based on the present value of future lease payments using an estimated rate of interest that we would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. We determine the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. Rent expense for operating leases is recognized on a straight-line basis over the lease term and is included in operating expenses in our consolidated statements of operations. For financing leases, interest expense and amortization of the ROU is included in operating expenses in our consolidated statements of operations and variable lease payments are recorded as incurred.

If a lease is modified, the modified contract is evaluated to determine whether it is or contains a lease. If a lease continues to exist, the lease modification is determined to be a separate contract when the modification grants the lessee an additional ROU that is not included in the original lease and the lease payments increase commensurate with the standalone price for the additional ROU. A lease modification that results in a separate contract will be accounted for in the same manner as a new lease. For a modification that is not a separate contract, we reassess the lease classification using the modified terms and conditions and the facts and circumstances as of the effective date of the modification and recognize the amount of the remeasurement of the lease liability for the modified lease as an adjustment to the corresponding lease ROU asset.

Our ROU assets consist of non-cancelable operating leases and financing leases. Non-cancelable operating leases consist of leases for our corporate headquarters and additional laboratory space. Financing leases consist of leases for various research and development and information technology equipment.

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

Revenue Recognition

We evaluate our agreements under ASC Topic 606, Revenue from Contracts with Customers and ASC Topic 808, Collaborative Arrangements. We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under our agreement, we perform the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) we satisfy each performance obligation. As part of the accounting for these arrangements, we must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. We use key assumptions to determine the stand-alone selling price, which may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success.

We recognize revenue in one of two ways, over time or at a point in time. We recognize revenue over time when we are executing on our performance obligation over time and our partner receives benefit over time. For example, we recognize revenue over time when we provide research and development services. We recognize revenue at a point in time when we transfer control of a distinct performance obligation to our partner. For example, if a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license.

Research and Development Costs

Research and development costs are expensed as incurred. Research and development costs include: salaries and employee-related expenses, including stock-based compensation and benefits for personnel in research and product development functions; costs associated with conducting our preclinical, development and regulatory activities, including fees paid to third-party professional consultants, service providers and our scientific, therapeutic and clinical advisors; costs to acquire, develop and manufacture preclinical study and clinical trial materials; costs incurred under clinical trial agreements with CROs and investigative sites; costs for laboratory supplies; payments related to licensed products and technologies; allocated facilities and information technology costs; and depreciation.

Patent Costs

Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain.

Stock-Based Compensation

We evaluate our stock-based compensation arrangements under ASC Topic 718, Compensation – Stock Compensation. Stock-based compensation expense represents the grant date fair value of employee stock option and restricted stock unit grants recognized as expense over the requisite service period of the awards (usually the vesting period) on a straight-line basis. We estimate fair value of stock option grants using the Black-Scholes option pricing model. We estimate the fair value using assumptions, including the risk-free interest rate, the expected volatility of a peer group of similar companies, the expected term of the awards and the expected dividend yield. These estimates involve inherent uncertainties and the application of management’s judgment. If factors change and different assumptions are used, our stock-based compensation expense could be materially different in the future.

Income Taxes

We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized as income in the period that includes the enactment date.

We recognize net deferred tax assets to the extent that we believe these assets are more likely than not to be realized. In making such a determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations. If we determine that we would be able to realize the deferred tax assets in the future in excess of their net recorded amount, we would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.

We record uncertain tax positions on the basis of a two-step process whereby (1) we determine whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, we recognize the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. We recognize interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted average number of common stock and common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of convertible preferred stock, warrants for common stock, options and restricted stock units outstanding under our stock option plans and inducement grants and estimated shares to be purchased under our 2015 Employee Stock Purchase Plan (the 2015 ESPP). For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position.

Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common share equivalents):

Years Ended December 31,

The following table summarizes our net loss per share (in thousands, except per share data):

Years Ended December 31,

Numerator:

Net loss attributable to aTyr Pharma, Inc. $ (50,389 ) $ (45,338 ) $ (33,768 )

Denominator:

Net loss per share - basic and diluted $ (0.94 ) $ (1.60 ) $ (1.77 )

Recent Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses (Topic 326), to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in Topic 326 replace the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Topic 326 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years for smaller reporting companies. We adopted Topic 326 on January 1, 2023. The adoption did not have a material impact on our consolidated financial statements.

In December 2023, the FASB, issued ASU 2023-09, Improvements to Income Tax Disclosures, which requires entities to disclose disaggregated information about their effective tax rate reconciliation as well as expanded information on income taxes paid by jurisdiction. The disclosure requirements will be applied on a prospective basis, with the option to apply them retrospectively. The standard is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. We are currently evaluating the disclosure requirements related to the new standard.

3. Fair Value Measurements

The carrying amounts of cash equivalents, prepaid and other assets, accounts payable and accrued liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. Investment securities are recorded at fair value.

The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:

Level 1: Observable inputs such as quoted prices in active markets.

Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly.

Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

Financial assets measured at fair value on a recurring basis consist of investment securities. Investment securities are recorded at fair value, defined as the exit price in the principal market in which we would transact, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Level 2 securities are valued using quoted market prices for similar instruments, non-binding market prices that are corroborated by observable market data, or discounted cash flow techniques and include our investments in commercial paper, corporate debt securities and U.S. government agencies. 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

Assets:

Current:

Available-for-sale investments:

Total available-for-sale investments 75,622 — 75,622 —

Fair Value Measurements Using

Assets:

Current:

Available-for-sale investments:

Total available-for-sale investments 56,165 — 56,165 —

As of December 31, 2023 and 2022, available-for-sale investments are detailed as follows (in thousands):

Available-for-sale investments:

We evaluate our available-for-sale debt securities for credit losses when the amortized cost basis exceeds fair value. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded in interest income through an allowance account. Unrealized gains and losses that are not credit-related are included in accumulated other comprehensive income (loss). When evaluating an investment for impairment, we review factors such as the severity of the impairment, changes in underlying credit ratings, our intent to sell or the likelihood that we would be required to sell the investment before its anticipated recovery in market value and the probability that the scheduled cash payments will continue to be made. Based on our evaluation, we did not record allowance for credit losses in the consolidated statement of operations during the year ended December 31, 2023.

As of December 31, 2023, all available-for-sale investments had a variety of effective maturity dates of less than two years. As of December 31, 2023, $74.6 million of our short-term investments had maturities less than one year and $1.0 million had maturities greater than one year. As of December 31, 2023, 19 out of 25 available-for-sale investments were in a gross unrealized loss position of which one available-for-sale investment with a market value of $2.0 million was in such position for greater than 12 months.

As of December 31, 2023 and 2022, accrued interest receivable on available-for-sale securities was $0.3 million and $0.2 million, respectively.

4. License, Collaboration and Other Agreements

Kyorin Pharmaceutical Co., Ltd.

In January 2020, we entered into a collaboration and license agreement (Kyorin Agreement) with Kyorin Pharmaceutical Co., Ltd. (Kyorin) for the development and commercialization of efzofitimod for the treatment of interstitial lung disease (ILD) in Japan. Under the Kyorin Agreement, Kyorin received an exclusive right to develop and commercialize efzofitimod in Japan for all forms of ILD, and is obligated to fund all research, development, regulatory, marketing and commercialization activities in Japan. In 2020, Kyorin conducted and funded a Phase 1 clinical trial of efzofitimod (known as KRP-R120 in Japan). The Phase 1 clinical trial was a placebo-controlled clinical trial to evaluate the safety, pharmacokinetics (PK) and immunogenicity of efzofitimod in 32 healthy Japanese male volunteers. Efzofitimod was observed to be generally well-tolerated with no drug-related serious adverse events, and PK findings were consistent with previous studies of efzofitimod. Kyorin is also participating in the EFZO-FIT study as the local sponsor in Japan. In February 2023, Kyorin dosed the first patient in Japan in the EFZO-FIT study which triggered a $10.0 million milestone payment to us. To date, the Kyorin Agreement has generated $20.0 million in upfront and milestone payments to us and we are eligible to receive up to an additional $155.0 million in the aggregate upon achievement of certain development, regulatory and sales milestones, as well as tiered royalties on any net sales in Japan.

Either party may terminate the Kyorin Agreement in the event that the other party breaches the agreement and fails to cure the breach, becomes insolvent or challenges certain of the intellectual property rights licensed under the agreement.

We assessed our license and collaboration with Kyorin in accordance with Topic 606 and concluded that Kyorin is a customer. We identified the following performance obligations under the Kyorin Agreement: 1) the license of efzofitimod for ILD in Japan; and 2) free clinical trial material for Kyorin’s Phase 1 clinical trial. Kyorin is participating in the EFZO-FIT study and received approval from the Pharmaceuticals and Medical Devices Agency (PMDA) to commence the EFZO-FIT study in Japan in December 2022. Additionally, in February 2023, Kyorin dosed the first patient in Japan in the EFZO-FIT study which triggered a $10.0 million milestone payment to us. We recognized this $10.0 million milestone payment as revenue during the year ended December 2022, as we determined the milestone became probable of achievement with Kyorin having scheduled site visits for patient screenings by that time. We received this $10.0 million milestone payment in February 2023. During the year ended December 31, 2023, we recognized $0.4 million in collaboration revenue from Kyorin for drug product material sold to Kyorin for the Japan portion of the EFZO-FIT study.

The remaining milestones and royalty payments under the Kyorin Agreement are variable consideration. Since the milestone payments are binary in nature, we will use the “most-likely” method to evaluate whether the milestones should be included as revenue. We will constrain these amounts until they become probable of being achieved. The royalties are dependent on future sales by Kyorin which are at the full discretion of Kyorin. Accordingly, we will apply a constraint to these amounts until the future sale sales have occurred.

5. Balance Sheet Details

Prepaid expenses consist of the following (in thousands):

December 31,

Prepaid clinical and research expense $ 1,475 $ 334

Prepaid manufacturing expenses 125 2,049

Property and equipment consist of the following (in thousands):

December 31,

Computer and office equipment $ 448 $ 620

Scientific and laboratory equipment 4,051 4,379

Less accumulated depreciation and amortization (4,621 ) (6,354 )

During the years ended December 31, 2023, 2022 and 2021, depreciation expense was $0.6 million, $0.2 million and $0.5 million, respectively.

Accrued expenses consist of the following (in thousands):

December 31,

Accrued salaries, wages and benefits $ 2,706 $ 2,781

Accrued clinical and manufacturing 7,753 5,151

6. Commitments and Contingencies

Operating Leases

Corporate Headquarters Facility Lease

In May 2022, we entered into a lease (the Lease) with San Diego Creekside, LLC (Landlord), as lessor, pursuant to which we agreed to lease from Landlord approximately 23,696 rentable square feet (subject to increase pursuant to the terms of the Lease) of office and laboratory space. The term of the lease (the Lease Term) commenced on March 20, 2023 (the Lease Commencement Date) and will 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 (as that term is defined in the Lease). 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 up to $5.3 million for tenant improvements of which as of December 31, 2023 we had received $5.0 million, and we received the remaining $0.3 million in February 2024. We provided a $0.7 million security deposit in the form of a letter of credit which is included in restricted cash as of December 31, 2023. During the second quarter of 2023, additional common area amenities were completed by the Landlord which provided us with access to approximately 1,500 additional rentable square feet. As a result, our base rent increased for this additional rentable square feet at the same monthly base rent per rentable square foot as contemplated in the Lease.

Previous Corporate Headquarters Facility Lease

Our operating lease for our previous corporate headquarters was subject to base lease payments, additional charges for common area maintenance and other costs and it expired in May 2023.

Future minimum payments under the facility lease and reconciliation to the operating lease liability as of December 31, 2023 were as follows (in thousands):

Operating Leases

Less: Amount representing interest (6,289 )

Present value of lease payments 13,468

Less: Current portion of operating lease liability (831 )

Less: Tenant improvement allowance not yet received (298 )

Long-term operating lease liability, net of current portion $ 12,339

Operating lease expense was $1.9 million, $1.5 million and $1.0 million for the years ended December 31, 2023, 2022 and 2021, respectively. As of December 31, 2023 and 2022, the weighted average remaining lease term was 9.4 years and 9.9 years, respectively. As of December 31, 2023 and 2022, the weighted average discount rate for each period was 8.8%.

Financing Leases

In April 2022, we entered into a master financing lease agreement to lease various research and development and information technology equipment over a 48-month term. Future minimum payments under the financing lease and reconciliation to the financing lease liability as of December 31, 2023 were as follows (in thousands):

Financing Leases

Less: Amount representing interest (283 )

Present value of lease payments 1,925

Less: Current portion of financing lease liability (497 )

Long-term financing lease liability, net of current portion $ 1,428

As of December 31, 2023 and 2022, the weighted-average remaining lease term was 3.0 years and 3.7 years, respectively and the weighted-average discount rate was 8.3% and 7.9%, respectively. We provided a $2.7 million deposit to be held as collateral for the leased equipment, and this deposit is included in restricted cash as of December 31, 2023.

7. Stockholders’ Equity

Underwritten Follow-On Public Offerings

At-the-Market Offering Programs

In April 2022, we entered into an Open Market Sale AgreementSM with Jefferies implementing the Jefferies ATM Offering Program, pursuant to which we may offer and sell, from time to time and at our option, up to an aggregate of $65.0 million of shares of our common stock through Jefferies, acting as sales agent. Jefferies is entitled to a fixed commission rate of up to 3.0% of the gross sales proceeds of shares sold under the Jefferies ATM Offering Program. During the year ended December 31, 2022, we sold an aggregate of 1,421,627 shares of common stock at a weighted-average price of $3.09 per share for net proceeds of approximately $4.0 million under the Jefferies ATM Offering Program. During the year ended December 31, 2023, we sold an aggregate of 10,530,795 shares of common stock at a weighted-average price of $1.82 per share for net proceeds of approximately $18.4 million under the Jefferies ATM Offering Program.

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 JonesTrading ATM Offering Program), pursuant to which we were entitled to sell from time to time, at our option, up to an aggregate of $25.0 million of shares of our common stock through JonesTrading, as sales agent or principal. JonesTrading was entitled to a commission at a fixed rate of up to 3.0% of the gross proceeds. During 2021, we sold an aggregate of 986,267 shares of common stock at a weighted-average price of $4.75 per share for net proceeds of $4.4 million under the JonesTrading ATM Offering Program. In April 2022, we terminated the JonesTrading ATM Offering Program. During 2022 and prior to termination in April 2022, we sold an aggregate of 260,455 shares of common stock at a weighted-average price of $6.07 per share for net proceeds of approximately $1.5 million under the JonesTrading ATM Offering Program.

Purchase Agreement

2014 Stock Plan

We adopted a stock option plan in 2007 (the 2007 Plan), which was subsequently amended, restated and renamed in July 2014 (the 2014 Plan) to provide for the incentive stock options, nonstatutory stock options, stock and rights to purchase restricted stock to eligible recipients. Recipients of incentive stock options are eligible to purchase shares of our common stock at an exercise price equal to no less than the estimated fair market value of such stock on the date of grant. The maximum term of options under the 2014 Plan is ten years. Options granted generally vest over four years. We ceased granting under the 2014 Plan after our IPO in May 2015. Shares underlying any awards under the 2014 Plan that are forfeited, canceled, reacquired by us prior to vesting, satisfied without the issuance of stock or otherwise terminated (other than by exercise) will be added to shares available for issuance under our 2015 Stock Option and Incentive Plan (the 2015 Stock Plan), which became effective in May 2015.

2015 Stock Plan

Total shares available for issuance under the 2015 Stock Plan as of December 31, 2023 were 3,964,555. Shares underlying any awards under the 2015 Stock Plan that are forfeited, canceled, reacquired by us prior to vesting, satisfied without the issuance of stock or otherwise terminated (other than by exercise) will be added to shares available for issuance under the 2015 Stock Plan.

The maximum term of options granted under 2015 Stock Plan is ten years. For an initial grant to an employee, 25% of the options generally vest on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years. For subsequent grants to an employee, the options generally vest monthly over a four-year term.

Inducement Plan

In March 2022, our board of directors approved and adopted our 2022 Inducement Plan (our Inducement Plan). Awards granted under our Inducement Plan are in accordance with Nasdaq Listing Rule 5635(c)(4). A total of 300,000 shares of our common stock were initially reserved for the issuance under our Inducement Plan.

The maximum term of options granted under our Inducement Plan is ten years. Each option vests over a period of four years, with 25% of the shares vesting on the one-year anniversary of the applicable vesting commencement date and the remaining 75% vesting in equal monthly installments over three years, thereafter, subject to continuous employment.

During the year ended December 31, 2023, we granted nonstatutory stock options under our Inducement Plan to purchase an aggregate of 23,400 shares of our common stock, with a weighted-average exercise price of $2.26 per share as inducement awards to new employees.

2015 Employee Stock Purchase Plan

As of December 31, 2023, total shares reserved for issuance under the 2015 ESPP were 727,311.

Stock-based Compensation

Stock Options

Stock option activity is summarized as follows:

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

Years Ended December 31,

Expected dividend yield 0.0 % 0.0 % 0.0 %

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

Years Ended December 31,

Expected dividend yield 0.0 % 0.0 % 0.0 %

Expected term. The expected term represents the period of time that options are expected to be outstanding. Because we do not have sufficient history of exercise behavior, we determine the expected life assumption using the simplified method, which is an average of the contractual term of the option and its vesting period.

Risk-free interest rate. We base the risk-free interest rate assumption on the U.S. Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued.

Expected volatility. The expected volatility assumption is based on our historical volatility as well as the volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology industry.

Expected dividend yield. We base the expected dividend yield assumption on the fact that we have never paid cash dividends and have no present intention to pay cash dividends.

Restricted Stock Units

Occasionally, we grant restricted stock units to employees. The fair value of restricted stock is determined by the closing price of our common stock reported on the Nasdaq Capital Market on the date of grant. Restricted stock unit activity is summarized as follows:

Number of OutstandingRestricted Stock Units Weighted-AverageGrant DateFair Value

The allocation of stock-based compensation for all options, including performance options with market condition and restricted stock units is as follows (in thousands):

Years Ended December 31,

Total stock-based compensation expense $ 2,600 $ 2,154 $ 1,614

The weighted-average grant date fair value per share of stock options granted by us, during the years ended December 31, 2023, 2022 and 2021 was $1.59, $2.49 and $3.82, respectively. The total grant date fair value of restricted stock units granted by us during the years ended December 31, 2023, 2022, and 2021 was approximately $0, $597,000 and $16,000, respectively. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2023, 2022 and 2021 was approximately $0, $1,000 and $80,000, respectively. The fair value of restricted stock units released during the years ended December 31, 2023, 2022 and 2021 was approximately $123,875, $6,000 and $31,000, respectively. As of December 31, 2023, total unrecognized share-based compensation expense related to unvested stock options and restricted stock units was approximately$4.6 million and $0.2 million, respectively. As of December 31, 2023, these unrecognized costs for options and restricted stock units are expected to be recognized ratably over a weighted-average period of approximately 2.3 years and 2.0 years, respectively.

Warrants

Warrants outstanding for the purchase of common stock as of December 31, 2023 were as follows:

Number Exercise Price Expiration

Outstanding Per Share Date

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance was as follows:

Common stock warrants 5,864

Common stock options and restricted stock units 4,020,154

Shares available under the 2015 equity incentive plan 3,964,555

Shares available under the 2022 inducement plan 95,367

Shares available under the employee stock purchase plan 727,311

8. Income Tax

Pretax losses were generated by both domestic and foreign operations as follows (in thousands):

Years Ended December 31,

For the years ended December 31, 2023, 2022, and 2021, we did not record a provision for income taxes due to a full valuation allowance against our deferred taxes. A reconciliation of the expected statutory federal income tax provision to the actual income tax provision is summarized as follows (in thousands):

Years Ended December 31,

State income taxes, net of federal benefit (2,171 ) (380 ) (2,313 )

Foreign rate differential 19 11 21

Change in tax rate (5 ) 34 52

Income tax (benefit) expense $ — $ — $ —

Deferred income taxes are provided for temporary differences in recognizing certain income and expense items for financial and tax reporting purposes. The deferred tax assets consisted primarily of the income tax benefits from net operating loss (NOL) carryforwards, research and development credits and capitalized research and development expenses, along with other accruals and reserves. Valuation allowances of $108.0 million and $95.5 million as of December 31, 2023 and 2022, respectively, have been recorded to offset deferred tax assets as realization of such assets does not meet the more-likely-than-not threshold under ASC 740, Accounting for Income Taxes.

Significant components of our deferred tax assets are summarized as follows (in thousands):

December 31,

Deferred tax assets:

Capitalized research and development expenses 25,922 22,576

Research credits and other state credits 18,246 16,021

Share-based compensation expense 1,821 1,628

Total deferred tax assets $ 1,414 $ 1,524

Deferred tax liabilities:

Right of use lease assets (1,414 ) (1,524 )

Total deferred tax liabilities (1,414 ) (1,524 )

Net deferred tax assets $ — $ —

The Tax Cuts and Jobs Act of 2017 requires taxpayers to capitalize and amortize research and development (R&D) expenditures under section 174 for tax years beginning after December 31, 2021. This rule was effective at the beginning of 2022 which resulted in a capitalization of R&D costs of approximately $44.2 million and $38.8 million during the years ended December 31, 2023 and 2022, respectively. We will amortize these costs for tax purposes over 5 years if the R&D was performed in the U.S. and over 15 years if the R&D was performed outside the U.S.

As of December 31, 2023, we had federal NOL carryforwards of approximately $257.4 million, with $144.9 million of NOLs generated after December 31, 2017 carrying forward indefinitely and $112.5 million of NOLs that will begin to expire in 2025. NOL carryforwards generated after January 1, 2018 are subject to an 80% of taxable income limitation in accordance with the Tax Cuts and Jobs Act of 2017. We had state net operating loss carryforwards of approximately $225.3 million, and foreign net operating loss carryforwards of $9.4 million. The state net operating losses began to expire in 2025. The foreign net operating losses carry over indefinitely.

As of December 31, 2023, we had federal and state research and development credit carryforwards of approximately $9.3 million and $5.8 million, respectively, which begin to expire in 2026 for both federal and state purposes. We had $18.4 million of federal Orphan Drug Credits as of December 31, 2023, which will begin to expire in 2035.

Utilization of the domestic NOL and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that may have occurred or that could occur in the future, as required by Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the Code), as well as similar state and foreign provisions. These ownership changes may limit the amount of NOL and research and development credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders. Since the Company’s formation, we raised capital through the issuance of capital stock on several occasions which on its own or combined with the purchasing stockholders’ subsequent disposition of those shares, has resulted in such an ownership change, and could result in an ownership change in the future.

Upon the occurrence of an ownership change under Section 382 as outlined above, utilization of the NOL and research and development credit carryforwards become subject to an annual limitation under Section 382 of the Code, which is determined by first multiplying the value of our stock at the time of the ownership change by the applicable long-term, tax-exempt rate, which could be subject to additional adjustments. Any limitation may result in expiration of a portion of our NOL or research and development credit carryforwards before utilization. Due to the existence of the valuation allowance, any impact to the NOL and research and development

tax credit carryforwards from Section 382 analysis will be offset by a corresponding adjustment to valuation allowance, resulting in no tax provision impact.

We recognize a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more-likely-than-not recognition threshold to be recognized.

Our practice is to recognize interest and penalties related to income tax matters in income tax expense. We had no accrual for interest and penalties on our balance sheet and had not recognized interest or penalties in the consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021.

Due to the existence of the valuation allowance, future changes in unrecognized tax benefits will not impact our effective tax rate.

Uncertain tax positions are evaluated based upon the facts and circumstances that exist at each reporting period. Subsequent changes in judgment based upon new information may lead to changes in recognition, derecognition, and measurement. Adjustments may result, for example, upon resolution of an issue with the taxing authorities, or expiration of a statute of limitations barring an assessment for an issue.

The activity related to our unrecognized tax benefits is summarized as follows (in thousands):

December 31,

Increase (decrease) related to prior year tax positions (483 ) (48 ) (9 )

Increase related to current year tax positions 5,416 2,961 534

We do not anticipate that the amount of unrecognized tax benefits as of December 31, 2023 will change within the next twelve months.

We are subject to taxation in the United States, Hong Kong and state jurisdictions. Our tax years from inception are subject to examination by the United States, Hong Kong and various state authorities due to carry forward of unutilized NOLs and research and development credits.

9. Employee Benefits

401(k) Plan

We maintain a defined contribution 401(k) plan available to eligible employees. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under federal tax regulations. In April 2015, our board of directors approved a policy, beginning on June 1, 2015, to match employee contributions equal to 50% of the participant’s contribution of up to a maximum of 6% of the participant’s annual salary. We made discretionary contributions totaling $0.2 million during each of the years ended December 31, 2023, 2022 and 2021.

10. Subsequent Events

Sales of Common Stock through the Jefferies ATM Offering Program

From January 1, 2024 through March 13, 2024, we sold an aggregate of 4,441,509 shares of common stock at a weighted-average price of $1.75 per share through the Jefferies ATM Offering Program for net proceeds of $7.6 million.

Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure.

None

Item 9A. Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

We maintain disclosure controls and procedures, as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act that are designed to ensure that information required to be disclosed in our periodic and current reports that we file with the SEC is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms, and that such information is accumulated and communicated to our management, including our Principal Executive Officer and Principal Financial Officer, as appropriate, to allow timely decisions regarding required disclosure. In designing and evaluating the disclosure controls and procedures, management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable and not absolute assurance of achieving the desired control objectives. In reaching a reasonable level of assurance, management necessarily is required to apply its judgment in evaluating the cost-benefit relationship of possible controls and procedures. In addition, the design of any system of controls also is based in part upon certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions; over time, control may become inadequate because of changes in conditions, or the degree of compliance with policies or procedures may deteriorate. Because of the inherent limitations in a cost-effective control system, misstatements due to error or fraud may occur and not be detected.

We carried out an evaluation, under the supervision and with the participation of our management, including our Principal Executive Officer and Principal Financial Officer, of the effectiveness of the design and operation of our disclosure controls and procedures, as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act. Based on this evaluation, our Principal Executive Officer and Principal Financial Officer concluded that our disclosure controls and procedures were effective at the reasonable assurance level as of December 31, 2023.

Management’s Report on Internal Control Over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting as such term is defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act. Internal control over financial reporting is a process designed by, or under the supervision of, our Principal Executive Officer and Principal Financial Officer, and effected by our board of directors, management and other personnel, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with accounting principles generally accepted in the United States of America.

As of December 31, 2023, our management assessed the effectiveness of our internal control over financial reporting using the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission in Internal Control – 2013 Integrated Framework (2013 Framework). Based on this assessment, our management concluded that our internal control over financial reporting was effective as of December 31, 2023.

This Annual Report does not include an attestation report of our registered public accounting firm under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)).

Changes in Internal Control Over Financial Reporting

During the quarter ended December 31, 2023, there have been no changes in our internal control over financial reporting, as such term is defined in Rules 13a-15(f) and 15d-15(f) promulgated under the Exchange Act, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Item 9B. Other Information.

None.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections.

Not applicable.

PART III

Item 10. Directors, Executive Officers and Corporate Governance.

Except as set forth below, the information required by this item will be contained in our Definitive Proxy Statement to be filed with the SEC in connection with our 2024 Annual Meeting of Stockholders within 120 days after the end of the fiscal year ended December 31, 2023, under the sections headed “Proposal 1 – Election of Directors,” “Executive Officers” and “Delinquent Section 16(a) Reports,” if any, and is incorporated herein by reference.

We have adopted a written code of ethics for directors, officers (including our principal executive officer, principal financial officer and principal accounting officer or controller, or persons performing similar functions) and employees, known as the Code of Business Conduct and Ethics. The Code of Business Conduct and Ethics is available on our website at http://www.atyrpharma.com under the Corporate Governance section of our Investors and Media page. If we make any amendments to, or grant any waivers from, the Code of Business Conduct and Ethics for any officer or director, we intend to satisfy our disclosure obligations, if any, with respect to such amendment or waiver by posting such information on our website or in a Current Report on Form 8-K. Information contained in, or that can be accessed through, our website is not incorporated by reference herein, and you should not consider information on our website to be part of this Annual Report.

Item 11. Executive Compensation.

The information required by this item will be contained in our Definitive Proxy Statement under the section headed “Executive Officers,” and is incorporated herein by reference.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

The information required by this item will be contained in our Definitive Proxy Statement, under the sections headed “Equity Compensation Plan Information and “Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters,” and is incorporated herein by reference.

Item 13. Certain Relationships and Related Transactions, and Director Independence.

The information required by this item will be contained in our Definitive Proxy Statement, under the sections headed “Proposal 1 – Election of Directors” and “Certain Relationships and Related Transactions,” and is incorporated herein by reference.

Item 14. Principal Accountant Fees and Services.

The information required by this item will be contained in our Definitive Proxy Statement, under the section headed “Proposal 2 – Ratification of the Independent Registered Public Accounting Firm,” and is incorporated herein by reference.

PART IV

Item 15. Exhibit and Financial Statement Schedules.

(a) The following documents are filed as part of this Annual Report.

1. Index list toFinancial Statements:

Page

Report of Independent Registered Public Accounting Firm (PCAOB ID: 42) 69

Consolidated Balance Sheets 71

Consolidated Statements of Operations 72

Consolidated Statements of Comprehensive Loss 73

Consolidated Statements of Stockholders’ Equity 74

Consolidated Statements of Cash Flows 75

Notes to Consolidated Financial Statements 76

2. Financial Statement Schedules.

Schedules have been omitted as all required information has been disclosed in the consolidated financial statements and related footnotes.

3. Exhibits.

The Exhibits listed in the Exhibit Index are filed as a part of this Annual Report.

EXHIBIT INDEX

Incorporated by Reference

ExhibitNumber Exhibit Title Form File No. Exhibit Filing Date

4.6 Description of Common Stock of the Registrant — — — Filed herewith

Incorporated by Reference

ExhibitNumber Exhibit Title Form File No. Exhibit Filing Date

10.19* Non-Employee Director Compensation Policy — — — Filed herewith

101.INS Inline XBRL Instance Document — — — Filed herewith

* Indicates a management contract or compensatory plan, contract or arrangement.

† Certain portions have been omitted because the Registrant has determined that the information is not material and is the type that the Registrant treats as private or confidential.

# The information in Exhibits 32.1 and 32.2 shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act or the Exchange Act (including this Annual Report on Form 10-K), unless the Registrant specifically incorporates the foregoing information into those documents by reference.

Item 16. Form 10-K Summary.

None.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

aTyr Pharma, Inc.

Date: March 14, 2024 By /s/ Sanjay S. Shukla

Sanjay S. Shukla, M.D., M.S.

President, Chief Executive Officer and Director

(Principal Executive Officer)

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Sanjay S. Shukla, M.D., M.S. and Jill M. Broadfoot, jointly and severally, and each of them, his or her true and lawful attorneys-in-fact, each with full power of substitution, for him or her in any and all capacities, to sign any amendments to this Annual Report on Form 10-K and to file the same, with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or their substitute or substitutes may do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Signature Title Date

Sanjay S. Shukla, M.D., M.S. (Principal Executive Officer)

/s/ Jill M. Broadfoot Chief Financial Officer March 14, 2024

Jill M. Broadfoot (Principal Financial and Accounting Officer)

/s/ Timothy P. Coughlin Chairman of the Board March 14, 2024

Timothy P. Coughlin

John K. Clarke

/s/ Jane A. Gross Director March 14, 2024

Jane A. Gross, Ph.D.

/s/ Svetlana Lucas Director March 14, 2024

Svetlana Lucas, Ph.D.

/s/ Paul Schimmel Director March 14, 2024

Paul Schimmel, Ph.D.

/s/ Sara L. Zaknoen Director March 14, 2024

Sara L. Zaknoen

ATYR US Equity

ATYR · 10-K · period ended 2023-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Item 8. Financial Statements and Supplementary Data.

Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure.

Item 9A. Controls and Procedures.

Item 9B. Other Information.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections.

Item 10. Directors, Executive Officers and Corporate Governance.

Item 11. Executive Compensation.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

Item 13. Certain Relationships and Related Transactions, and Director Independence.

Item 14. Principal Accountant Fees and Services.

Item 15. Exhibit and Financial Statement Schedules.

Item 16. Form 10-K Summary.

ATYR US Equity☆

ATYR · 10-K · period ended 2023-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Item 8. Financial Statements and Supplementary Data.

Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure.

Item 9A. Controls and Procedures.

Item 9B. Other Information.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections.

Item 10. Directors, Executive Officers and Corporate Governance.

Item 11. Executive Compensation.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

Item 13. Certain Relationships and Related Transactions, and Director Independence.

Item 14. Principal Accountant Fees and Services.

Item 15. Exhibit and Financial Statement Schedules.

Item 16. Form 10-K Summary.

ATYR US Equity