aTYR PHARMA INC (ATYR)

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

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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). The Pharmaceutical and Medical Devices Agency (PMDA) has granted efzofitimod orphan drug designation for the treatment of sarcoidosis to Kyorin Pharmaceutical Co., Ltd. (Kyorin), our partner in Japan.

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 October 2024, the same published data for efzofitimod was featured in the Best of CHEST Journals session at the CHEST 2024 Annual Meeting.

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. We expected the study 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 the study. During 2023 and 2024, we have had data and safety monitoring board (DSMB) reviews of our EFZO-FIT study. The DSMB reviews concluded that the study could continue unmodified. In July 2024, we completed enrollment of 268 patients, exceeding target enrollment. Topline data from the study are anticipated in the third quarter of 2025.

In February 2024, we announced an Individual Patient Expanded Access Program (Individual Patient EAP). The Individual Patient EAP has been initiated based on blinded EFZO-FIT study investigator and patient participant feedback. The program is designed to allow access for patients who complete the Phase 3 EFZO-FIT 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 (limited or diffuse) and systemic manifestations in patients with SSc-ILD. The primary endpoint is reduction in FVC. Secondary endpoints include certain measures regarding safety and tolerability. In July 2024, we amended the study to add an open label extension (OLE) to patients. Patients who complete the study and wish to receive ongoing treatment with efzofitimod are eligible to participate in the 24-week OLE. Based on current enrollment projections, we expect to report interim data from the study in the second quarter of 2025.

In January 2020, we entered into a collaboration and license agreement (Kyorin Agreement) with Kyorin for the development and commercialization of efzofitimod for the treatment of ILD in Japan. Under the terms of the Kyorin Agreement, Kyorin received exclusive rights 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. We are responsible for supplying all drug product for Japan, as well as supporting development activities for efzofitimod. 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

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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.

tRNA Synthetase Candidates

Utilizing our novel approach, we have identified target receptors for domains of two additional tRNA synthetases, gaining insights into their potential biological activity in immunology and fibrosis. These fragments form the basis of our additional pipeline candidates. We plan to further elucidate the therapeutic potential of these candidates through mechanistic investigations, including in vitro and in vivo preclinical studies.

ATYR0101

ATYR0101 is a fusion protein derived from a domain of aspartyl-tRNA synthetase (DARS). ATYR0101 binds directly to latent-transforming growth factor beta-binding protein 1 (LTBP1), which regulates transforming growth factor beta (TGFβ), which is at the apex of fibrotic signaling. Derived from a naturally occurring tRNA synthetase, ATYR0101 interacts with LTBP1 in a unique way that presents a differentiated approach to targeting fibrosis. Early data suggest ATYR0101 exerts its antifibrotic effects by inducing apoptosis of myofibroblasts in a TGFβ dependent manner. We believe ATYR0101 may have broad therapeutic applications in multiple fibrotic diseases, such as pulmonary fibrosis, SSc, liver fibrosis and kidney fibrosis.

ATYR0750

ATYR0750 is a fusion protein derived from a domain of alanyl-tRNA synthetase (AARS). ATYR0750 is a novel ligand to fibroblast growth factor receptor 4 (FGFR4), which is involved in many cellular processes, including cell proliferation, differentiation, and tissue repair. FGFR4 is known to play a role in diseases related to inflammation and fibrosis, particularly in the liver. As a novel ligand, ATYR0750 interacts with FGFR4 in a differentiated way to other approaches targeting the receptor, which may lead to improved therapeutic benefit.

Liquidity and Capital Resources

We have incurred losses and negative cash flows from operations since our inception. As of December 31, 2024, we had an accumulated deficit of $532.0 million, and we expect to continue to incur net losses for the foreseeable future. As of December 31, 2024, we had cash, cash equivalents, restricted cash and available-for-sale investments of $75.1 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, 2024, 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.

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At-the-Market Offering Programs

In April 2022, we entered into an Open Market Sale AgreementSM with Jefferies LLC (Jefferies) implementing an “at-the-market” offering program, (the Jefferies ATM Offering Program). In December 2024, we amended the Jefferies ATM Offering Program. Under the Jefferies ATM Offering Program we may offer and sell, from time to time and at our option, up to an aggregate of $215.0 million of shares of our common stock (inclusive of $65.0 million of sales made prior to the amendment) 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. During the year ended December 31, 2024, we sold an aggregate of 20,653,450 shares of common stock at a weighted-average price of $2.02 per share for net proceeds of approximately $40.3 million under the Jefferies ATM Offering Program.

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):

Operating activities. Net cash used in operating activities for the years ended December 31, 2024, 2023 and 2022, was $69.1 million, $33.2 million and $41.9 million, respectively. Net cash used in operating activities increased during the year ended December 31, 2024 primarily due to increased costs for the EFZO-FIT and EFZO-CONNECT studies and upfront payments for manufacturing efforts toward and preparation for a possible biologics license application (BLA) for efzofitimod. Net cash used in operating activities during the year ended December 31, 2023 also included the receipt of a $10.0 million milestone 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 provided by (used in) investing activities for the years ended December 31, 2024, 2023 and 2022 was $17.2 million, $(20.1) million and $47.2 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, 2024 was less than one year. 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, 2024 was $39.9 million and consisted primarily of $40.3 million in proceeds from our Jefferies ATM Offering Program, net of issuance costs. 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 $5.5 million and consisted primarily of cash 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, regulatory and

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pre-commercialization 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, 2024, our material cash requirements from known contractual and other obligations consisted primarily of (i) an operating lease 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 (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 was $5.75 per square foot of rentable area per month, and the base rent following the first 12 months of the Lease Term is subject to certain upward adjustments of approximately 3.0% annually. We received $5.3 million in allowance payments for tenant improvements, which represents the full allowance to which we were entitled under the Lease. 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, 2024. During the second quarter of 2023, additional common area amenities were completed by the Landlord which provided us with access to an estimated 1,500 additional rentable square feet. In April 2024, we finalized an amendment to the Lease (the Lease Amendment), effective June 2023. The additional rentable square feet was adjusted to 1,170 square feet for a total of 24,866 rentable square feet and 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 totaled $1.4 million as of December 31, 2024. Additionally, we provided $2.3 million in cash collateral for the financing lease, and this amount is included in restricted cash as of December 31, 2024.

We did not have any off-balance sheet arrangements as of December 31, 2024.

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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, 2024. 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 terms of the Kyorin Agreement, Kyorin received exclusive rights 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. We are responsible for supplying all drug product for Japan, as well as supporting development activities for efzofitimod. In 2020, Kyorin conducted and funded a Phase 1 clinical trial of efzofitimod (known as KRP-R120 in Japan). The Phase 1 clinical trial, which was conducted and funded by Kyorin, was a placebo-controlled 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 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. During the year ended December 31, 2024, we recognized $0.2 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:

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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, such as efzofitimod, 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 primarily outsource our clinical trial administration to CROs, and we outsource our manufacturing of clinical trial materials to CDMOs. These outsourced expenses are typically substantially higher than the expenses we incur on our other product candidates which are all currently in preclinical development. As such, we separately track and report on the majority of our research and development expenses associated with the advancement of efzofitimod. For our candidates in preclinical development, the nature of the research and development expenses incurred to advance these candidates is primarily internal personnel and laboratory supply expenses. We do not fully track or allocate these internal expenses between preclinical product candidates because the expenses can often be shared between candidates. We also incur other shared expenses to support our research and development efforts such as facilities expenses, and these expenses are not allocated to efzofitimod or our preclinical product candidates. Additionally, non-cash research and development expenses such as depreciation and stock-based compensation are not tracked or allocated between product candidates and are shared among all product candidates.

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

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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.

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Results of Operations

Comparison of the Years Ended December 31, 2024 and 2023

In this section, we discuss the results of our operations for the year ended December 31, 2024, compared to the year ended December 31, 2023. For a discussion of the year ended December 31, 2023 compared to the year ended December 31, 2022, please refer to our Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 14, 2024.

The following table summarizes our results of operations for the years ended December 31, 2024 and 2023 (in thousands):

License and collaboration agreement revenues. Revenues of $0.2 million and $0.4 million for the years ended December 31, 2024 and 2023, respectively, consisted of drug product material sold to Kyorin for the Japan portion of the EFZO-FIT study.

Research and development expenses. Research and development expenses were $54.4 million and $42.3 million for the years ended December 31, 2024 and 2023, respectively. The increase of $12.1 million was due primarily to an increase of $12.2 million in efzofitimod expenses for the advancement of the EFZO-FIT study as well as increased manufacturing efforts for preparation toward a possible BLA. Preclinical development and other shared research and development expenses decreased by $0.3 million, and this decrease was primarily attributable to reduced discovery costs for our preclinical product candidates. Non-cash expenses increased by $0.2 million primarily due to increased non-cash depreciation expense associated with tenant improvements to our corporate headquarters facility. We expect research and development expenses as we advance clinical and manufacturing efforts toward possible commercialization of efzofitimod.

General and administrative expenses. General and administrative expenses were $13.8 million and $13.0 million for the years ended December 31, 2024 and 2023, respectively. The increase of $0.8 million was attributable to higher personnel related costs as well as higher professional fees. Non-cash expenses increased by $0.3 million primarily due to increased non-cash stock-based compensation expenses.

Other income (expense), net. Other income (expense), net was $3.9 million and $4.5 million for years ended December 31, 2024 and 2023, respectively. The change was primarily a result of lower interest income earned on lower cash balances as compared to the same period in the prior year.

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 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

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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-FIT™ study investigator and patient participant feedback. The program is designed to allow access for patients who complete the Phase 3 EFZO-FIT™ 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

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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.

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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):

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.

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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.

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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:

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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

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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.

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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):

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 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 biotherapeutics company engaged in the discovery and development of first-in-class medicines from our proprietary tRNA synthetase platform. We have concentrated our research and development efforts on a newly discovered area of biology, the extracellular functionality and signaling pathways of tRNA synthetases. Built on more than a decade of foundational science on extracellular tRNA synthetase biology and its effect on immune responses, we have built a global intellectual property estate directed to a potential pipeline of protein compositions derived from 20 tRNA synthetase genes and their extracellular targets, such as neuropilin-2 (NRP2).

Efzofitimod

Our primary focus is efzofitimod, a clinical-stage product candidate which targets NRP2 to resolve chronic inflammation that can lead to fibrosis. Efzofitimod has a novel mechanism of action for potentially treating lung inflammation and fibrosis. We believe by targeting NRP2 on myeloid cells during active inflammation, efzofitimod works upstream of currently available immunomodulators to restore immune homeostasis, thereby resolving chronic inflammation and preventing the progression of fibrosis. We are developing efzofitimod as a potential disease-modifying therapy for patients with interstitial lung disease (ILD). 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. During 2022, the U.S. Food and Drug Administration (FDA) 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. In January 2023, the European Commission granted efzofitimod an orphan drug designation for the treatment of sarcoidosis 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 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 264 subjects with pulmonary sarcoidosis at multiple centers in the United States, Europe and Japan. The trial design incorporates a forced steroid taper. The primary endpoint of the study is steroid reduction. Secondary endpoints include measures of lung function and sarcoidosis symptoms. In September 2022, we dosed the first patient in this study.

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 study of efzofitimod in patients with SSc-ILD and we have received FDA clearance for this study. In February 2023, we announced that we plan to initiate this Phase 2 study of efzofitimod in patients with SSc-ILD in 2023. This planned Phase 2 study is expected to be 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 expected to be 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. It is expected the study will enroll 25 patients at multiple centers in the United States. The primary objective of the study will be to evaluate the efficacy of multiple doses of intravenous (IV) efzofitimod on pulmonary, cutaneous and systemic manifestations in patients with SSc-ILD. Secondary objectives will include safety and tolerability.

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,

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

Discovery Pipeline

Extracellular tRNA synthetase biology represents a novel set of potential physiological modulators and therapeutic targets.

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 industry and academic collaborations, including our collaboration with Dualsystems Biotech AG (Dualsystems). Dualsystems has agreed to utilize their proprietary receptor screening technology and research expertise to attempt to identify and validate new target receptors for tRNA synthetases. Through our internal research efforts, the Dualsystems collaboration and other industry and academic collaborators, we intend to continue to advance our product development efforts within our tRNA synthetase biology platform.

We have also advanced our preclinical pipeline of NRP2 targeting antibody candidates through internal research efforts and academic collaborations. ATYR2810 is a product candidate from our NRP2 antibody program that we believe is ready to enter clinical trials. In the third quarter of 2022, we announced that we intend to focus our resources on the efzofitimod program. Therefore, we have made the strategic decision not to use internal resources to initiate a Phase 1 study of ATYR2810 at this time. We intend to pursue alternative avenues to advance this program.

Impact of the COVID-19 Pandemic and Other Geopolitical and Macroeconomic Conditions

The impacts of the COVID-19 pandemic on our business have included the delay in enrollment of our now completed Phase 1b/2a clinical trial in patients with pulmonary sarcoidosis and the discontinuation of some patients in that trial, temporary closures of portions of our facilities and those of our licensees and collaborators, disruptions or restrictions on our employees’ ability to travel and delays in certain research and development activities. Other potential impacts to our business include, but are not limited to, disruptions to or delays in other clinical trials, third-party manufacturing supply and other operations, the potential diversion of healthcare resources away from the conduct of clinical trials to focus on pandemic concerns, interruptions or delays in the operations of the FDA or other regulatory authorities, and our ability to raise capital and conduct business development activities.

In February 2022, the U.S. and global financial markets experienced volatility following the invasion of Ukraine by Russia, which has led to disruptions to trade, commerce, pricing stability, credit availability and supply chain continuity globally. In response to the invasion, the United States, United Kingdom and European Union (EU), along with others, imposed significant new sanctions and export controls against Russia, Russian banks and certain Russian individuals and may implement additional sanctions or take further punitive actions in the future. The full economic and social impact of the sanctions imposed on Russia (as well as possible future punitive measures that may be implemented), as well as the counter measures imposed by Russia, in addition to the ongoing Ukraine-Russia conflict, which could conceivably expand into the surrounding region, remains uncertain; however, both the conflict and related sanctions have resulted and could continue to result in disruptions to trade, commerce, pricing stability, credit availability and supply chain continuity in both Europe and globally, and has introduced significant uncertainty into global markets. As a result, our business and results of operations may be adversely affected by the ongoing Ukraine-Russia conflict, particularly to the extent it escalates to involve additional countries, further economic sanctions or wider military conflict.

In addition to the COVID-19 pandemic and the ongoing Ukraine-Russia conflict, global economic and business activities continue to face widespread macroeconomic uncertainties, including labor shortages, inflation and monetary supply shifts, 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 the COVID-19 pandemic, the ongoing Ukraine-Russia conflict and other 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

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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, 2022, we had an accumulated deficit of $417.6.million, and we expect to continue to incur net losses for the foreseeable future. As of December 31, 2022, we had cash, cash equivalents, restricted cash and available-for-sale investments of $69.3 million. Additionally, in February 2023, we completed an underwritten follow-on public offering of 23,125,000 shares of our common stock, including the partial exercise of the underwriters’ option to purchase additional shares, at a price to the public of $2.25 per share. The total gross proceeds from the offering were approximately $52.0 million, before deducting underwriting discounts, commissions and offering expenses payable by us. We also received a $10.0 million milestone payment from the Kyorin Agreement in February 2023. Additionally, in April 2022, we entered into an Open Market Sale AgreementSM with Jefferies LLC (Jefferies) implementing an “at-the-market” offering program (the Jefferies ATM Offering Program), pursuant to which we may offer and sell, from time to time and at our option, up to an aggregate of $65.0 million of shares of our common stock through Jefferies, acting as sales agent. Jefferies is entitled to a fixed commission rate of up to 3.0% of the gross sales proceeds of shares sold under the Jefferies ATM Offering Program. During the year ended December 31, 2022, we sold an aggregate of 1,421,627 shares of common stock at a weighted-average price of $3.09 per share for net proceeds of approximately $4.0 million under the Jefferies ATM Offering Program. 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. We believe we will meet longer-term material cash requirements from known contractual and other obligations through a combination of cash, cash equivalents, restricted cash and available-for-sale investments. In addition to the factors discussed under “Material Cash Requirements,” our ability to fund our longer-term operating needs beyond the next 12 months 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, 2022, 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 gross proceeds from the offering were approximately $52.0 million, before deducting underwriting discounts, commissions and offering expenses payable by us.

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

In February 2020, we completed an underwritten follow-on public offering of 4,235,294 shares of our common stock at a price to the public of $4.25 per share. In March 2020, the underwriters fully exercised their option to purchase additional shares resulting in the issuance of an additional 635,294 shares of common stock. The total net proceeds from the offering were approximately $18.8 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 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.

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

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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, we sold an aggregate of 260,455 shares of common stock at a weighted-average price of $6.07 per share for net proceeds of approximately $1.5 million under the JonesTrading ATM Offering Program.

In May 2019, we entered into a sales agreement with H.C. Wainwright & Co., LLC (Wainwright) for an “at-the-market” 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 Wainwright ATM Offering Program with Wainwright automatically terminated upon the issuance and sale of all of the shares having an aggregate offering price of $20.0 million. Under the Wainwright ATM Offering Program, during 2020, we sold an aggregate of 1,657,075 shares of common stock at an average price of $4.07 per share for net proceeds of $6.4 million. Prior to the termination of the sales agreement with Wainwright, in 2021, we sold an aggregate of 1,988,254 shares of common stock at an average price of $4.99 per share for net proceeds of $9.6 million.

Purchase Agreement

In September 2020, we entered into a common stock purchase agreement (the Purchase Agreement) with Aspire Capital Fund, LLC (Aspire Capital), which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $20.0 million of shares of our common stock at our request from time to time during the 30 month term of the Purchase Agreement. Concurrently with entering into the Purchase Agreement, we also entered into a registration rights agreement with Aspire Capital, in which we agreed to file one or more registration statements, as permissible and necessary to register under the Securities Act for the resale of the shares of our common stock that have been and may be issued to Aspire Capital under the Purchase Agreement. During 2021, we sold an aggregate of 3,000,000 shares of common stock at a weighted-average price of $5.09 per share for net proceeds of $15.2 million under the Purchase Agreement. During the year ended December 31, 2022, there were no issuances or sales under the Purchase Agreement, and this agreement terminated effective 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 the year ended December 31, 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):

Operating activities. Net cash used in operating activities was $41.9 million, $33.1 million and $15.3 million for the years ended December 31, 2022, 2021 and 2020, respectively. The net cash used in operating activities in each of these periods was primarily due to cash used for our research and development expenses. The increase in 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 trials.

Investing activities. Net cash provided by (used in) investing activities for the years ended December 31, 2022, 2021 and 2020 was $47.2 million, $(91.6) million and $6.9 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, 2022 was less than two years. Net cash used for December 31, 2022 included $1.6 million purchases of property and equipment primarily for tenant improvements associated with our new corporate headquarters facility lease.

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Financing activities. Net cash provided by financing activities for the year ended December 31, 2022 was $5.5 million, primarily due to cash provided by 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 the Purchase Agreement, net of offering costs, and $14.1 million proceeds from our ATM offering programs, net of issuance costs. Net cash provided by financing activities for the year ended December 31, 2020 was $16.1 million and consisted primarily of $18.8 million in proceeds from an underwritten follow-on public offering, net of offering costs, and $6.4 million proceeds from our ATM offering programs, net of issuance costs, offset in part by $9.1 million of principal payments and final payment on term loans.

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 NRP2 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, including:

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the type, number, scope progress, expansions, results, costs and timing of, our clinical trials and preclinical studies for our product candidates or other potential product candidates or indications which we are pursuing or may choose to pursue in the future, including changes in our CROs;

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the costs, timing and outcome of regulatory review of our product candidates;

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potential delays of our planned clinical trials of efzofitimod;

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any resulting cost increases as a result of the COVID-19 pandemic, the ongoing Ukraine-Russia conflict, other geopolitical and macroeconomic conditions, including labor shortages, economic slowdowns, recessions or market corrections, inflation and monetary supply shifts, rising interest rates and tightening of credit markets;

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the number and characteristics of product candidates that we pursue;

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the scope, progress, results and costs of preclinical development, and clinical trials for other product candidates;

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the manufacturing of preclinical study and clinical trial materials, including technology transfers to additional contract development and manufacturing organizations (CDMO), and any delays in the manufacturing of study drug as a result of the COVID-19 pandemic, the ongoing Ukraine-Russia conflict, and other geopolitical and macroeconomic conditions including labor shortages, economic slowdowns, recessions or market corrections, inflation, rising interest rates and tightening of credit markets;

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our ability to maintain existing and enter into new collaboration and licensing arrangements and the timing of any payments we may receive under such arrangements;

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the costs and timing of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending any intellectual property-related claims;

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the costs and timing of future commercialization activities, including product manufacturing, marketing, sales and distribution, for any of our product candidates for which we receive marketing approval; and

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the extent to which we acquire or in-license other products and technologies and the extent to which we are able to collaborate with a third party on ATYR2810.

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

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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, 2022, our material cash requirements from known contractual and other obligations consisted primarily of (i) our non-cancelable operating lease for our existing office and laboratory space, (ii) the lease that we entered into in May 2022 for our new corporate headquarters, and (iii) our master financing lease agreement that we entered into in April 2022 for various research and development and informational technology equipment.

Existing Corporate Headquarters Facility Lease

Our non-cancelable operating lease is subject to base lease payments, which escalate over the term of the lease, additional charges for common area maintenance and other costs. In July 2018, we entered into a lease amendment that reduced the space we lease from 24,494 square feet to 20,508 square feet and extended the lease term to May 2023. With the lease amendment, we do not have an option to extend our non-cancelable operating lease.

New 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) will commence upon the earlier of April 1, 2023 or the completion of certain leasehold improvements to the Premises (as defined in the Lease), but not sooner than March 1, 2023 (the Lease Commencement Date) and continue for 124 months from the Lease Commencement Date. We also have one option to extend the Lease Term for five years. Base rent during such extension period would be at the fair market rent for the Premises. Under the terms of the Lease, the base rent during the first 12 months of the Lease Term will be $5.75 per square foot of rentable area per month, subject to certain upward adjustments of approximately 3.0% annually. We are entitled to an allowance of up to $5.5 million for tenant improvements of which as of December 31, 2022, we received $1.8 million from the Landlord. The Lease also included an option to utilize an additional allowance of up to $0.6 million, which, if used by us, would be repaid by us as additional monthly base rent, amortized at eight percent (8.0%) per annum during the Lease Term. We provided a $0.7 million security deposit in the form of a letter of credit which is included in restricted cash as of December 31, 2022.

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 $0.8 million as of December 31, 2022. Additionally, we provided $2.4 million in cash collateral for the financing lease, and this amount is included in restricted cash as of December 31, 2022.

We did not have any off-balance sheet arrangements as of December 31, 2022.

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, 2022. All intercompany transactions and balances are eliminated in consolidation.

Revenue Recognition

In January 2020, we entered into a collaboration and license agreement with Kyorin for the development and commercialization of efzofitimod for ILD in Japan. Under the Kyorin Agreement, Kyorin received an exclusive right to develop and commercialize efzofitimod in Japan for all forms of ILD. Under the terms of the Kyorin Agreement, Kyorin will fund all research, development, regulatory, marketing and commercialization activities in Japan. The Phase 1 trial, which was conducted and funded by Kyorin, is a placebo-controlled study 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 EFZO-FIT study. This achievement has triggered a $10.0 million milestone payment by Kyorin to us pursuant to the Kyorin Agreement. 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

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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.

Kyorin is participating in the EFZO-FIT study and received approval from the Pharmaceuticals and Medical Devices Agency (PMDA) to commence the EFZO-FIT study in Japan during the year ended December 31, 2022. As of December 31, 2022, Kyorin had scheduled site visits for patient screenings which led to first patient dosing in February 2023. We determined that the development milestone achieved in February 2023 became probable of achievement as of December 31, 2022. Because our performance obligations were already completed, we recorded the $10.0 million collaboration revenue and a receivable from Kyorin as of December 31, 2022. We also recorded an additional $0.4 million in collaboration revenue from Kyorin during the year ended December 31, 2022 for drug product material sold to Kyorin for the Japan portion of the EFZO-FIT study.

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 and, more recently research efforts related to NRP2 biology. These expenses consist primarily of:

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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 clinical research organizations (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 and NRP2 biology.

We cannot determine with certainty the timing of initiation, the duration or the completion costs of current or future preclinical studies and clinical trials of our product candidates. For instance, as a result of the COVID-19 pandemic, many clinical trial sites in our completed Phase 1b/2a clinical trial in patients with pulmonary sarcoidosis temporarily suspended dosing of previously-enrolled patients and/or enrollment of new patients and some patients discontinued from the trial.

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

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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. Though the impact of the COVID-19 pandemic, the ongoing Ukraine-Russian conflict and other geopolitical and macroeconomic conditions on our business and operating results presents additional uncertainty, we continue to use the best information available to us in our critical accounting estimates.

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, 2022 and 2021

The following table summarizes our results of operations for the years ended December 31, 2022 and 2021 (in thousands):

License and collaboration agreement revenues. 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.

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Research and development expenses. Research and development expenses were $42.8 million and $23.3 million for the years ended December 31, 2022 and 2021, respectively. The increase of $19.5 million was due primarily to $8.7 million in clinical trial costs for the EFZO-FIT study that was initiated during the year ended December 31, 2022, an increase of $7.1 million in manufacturing costs for efzofitimod and ATYR2810, an increase of $1.2 million research and development costs for efzofitimod and our discovery programs and an increase of $2.5 million in compensation-related expenses.

General and administrative expenses. General and administrative expenses were $14.0 million and $10.8 million for the years ended December 31, 2022 and 2021, respectively. The increase of $3.2 million was due primarily to an increase of $1.9 million in compensation-related expenses, a $0.5 million increase in professional fees, a $0.2 million increase in travel costs and $0.2 million increase in facilities and information technology costs.

Other income (expense), net. Other income (expense), net was $1.1 million and $0.2 million for years ended December 31, 2022 and 2021, respectively. The increase was primarily a result of interest earned on higher cash, cash equivalents, restricted cash and available-for-sale investments balances, which resulted primarily from the underwritten follow-on offering in September 2021, as well as higher interest rates as of December 31, 2022 compared to the prior year.

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

You should read the following discussion and analysis together with and 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 biotherapeutics company engaged in the discovery and development of innovative medicines based on novel biological pathways. We have concentrated our research and development efforts on a newly discovered area of biology, the extracellular functionality and signaling pathways of tRNA synthetases. Built on more than a decade of foundational science on extracellular tRNA synthetase biology and its effect on immune responses, we have built a global intellectual property estate directed to a potential pipeline of protein compositions derived from 20 tRNA synthetase genes and their extracellular targets, such as neuropilin-2 (NRP2).

Our lead therapeutic candidate, efzofitimod (the non-proprietary name for ATYR1923), is a fusion protein comprised of the immunomodulatory domain of histidyl-tRNA synthetase fused to the fragment crystallizable (Fc) region of a human antibody, and serves as a selective modulator of NRP2 that downregulates innate and adaptive immune response in inflammatory disease states. We are developing efzofitimod as a potential disease-modifying therapy for patients with fibrotic lung diseases with high unmet medical need. This includes interstitial lung diseases (ILD), a group of rare immune-mediated disorders that cause progressive fibrosis of the lung. In December 2018, we designed a Phase 1b/2a multiple-ascending dose, double-blind, placebo-controlled clinical trial in patients with pulmonary sarcoidosis, a major form of ILD, to evaluate the safety, tolerability, immunogenicity and steroid-sparing effect of efzofitimod, and conduct other exploratory assessments of efficacy, such as lung function. In September 2021, we announced positive results and clinical proof-of-concept from the Phase 1b/2a clinical trial in 37 patients with pulmonary sarcoidosis. 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. Based on the results of this study, we met with the U.S. Food and Drug Administration (FDA) in February 2022 and presented these data and our plans for subsequent clinical development and path to registration for efzofitimod for the treatment of pulmonary sarcoidosis. As a result of the meeting, we intend to initiate a planned registrational trial of efzofitimod in the third quarter of 2022. 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).

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 September 2020,

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Kyorin began dosing patients in a Phase 1 clinical trial of efzofitimod (known as KRP-R120 in Japan) and completed the last subject visit in December 2020. The Phase 1 clinical trial, which was conducted and funded by Kyorin, was a placebo-controlled clinical trial to evaluate the safety, pharmacokinetics (PK) and immunogenicity of efzofitimod in 32 healthy Japanese male volunteers. Efzofitimod was observed to be generally well-tolerated with no drug-related serious adverse events, and PK findings were consistent with previous studies of efzofitimod. We received an $8.0 million upfront payment in January 2020 and a $2.0 million milestone payment in January 2021 upon completion of enrollment in the Phase 1 clinical trial, and we are eligible to receive up to an additional $165.0 million in the aggregate upon achievement of certain development, regulatory and sales milestones, as well as tiered royalties ranging from the mid-single digits to mid-teens on net sales in Japan.

In January 2022, the FDA granted efzofitimod an orphan drug designation for the treatment of sarcoidosis.

In parallel with our clinical development of efzofitimod, we have been advancing our discovery pipeline of NRP2 antibodies and tRNA synthetases. In November 2020, we announced ATYR2810 as our lead Investigational New Drug (IND) candidate in oncology from our NRP2 antibody program. ATYR2810 is a fully humanized monoclonal antibody that is designed to specifically and functionally block the interaction between NRP2 and vascular endothelial growth factor (VEGF). NRP2 is a pleiotropic cell surface receptor that is highly expressed on certain tumors and increased NRP2 expression is associated with worse outcomes in many cancers, such as overall survival, metastasis and resistance to targeted therapies. The role of NRP2 and VEGF signaling in the tumor microenvironment and its importance in the progression of certain aggressive cancers is becoming increasingly validated. ATYR2810 is in preclinical development for the potential treatment of certain aggressive cancers where NRP2 is implicated, and we plan to initiate a Phase 1 clinical trial in the second half of 2022.

In March 2020, our subsidiary, Pangu BioPharma Limited (Pangu BioPharma), together with the Hong Kong University of Science and Technology (HKUST) was awarded a grant of approximately $750,000 to build a high-throughput platform for the development of bi-specific antibodies. The project is being funded by the Hong Kong government’s Innovation and Technology Commission (ITC) under the Partnership Research Program (PRP). The PRP aims to support research and development projects undertaken by companies in collaboration with local universities and public research institutions. The ITC funded approximately 50% of the total estimated project cost, and we contributed the remaining 50%. The term of the project was initially for two years and in December 2021, due to complications arising from the ongoing COVID-19 pandemic, was extended for an additional six months with no additional costs. In May 2021, we announced that Pangu and HKUST achieved certain milestones for the first year of the project.

In February 2021, we announced two new discovery programs from our tRNA synthetase platform. These programs will investigate the functionality of selected fragments of Alanyl-tRNA synthetase (AARS) and Aspartyl-tRNA synthetase (DARS) in immunology, fibrosis and cancer. We are also advancing our preclinical pipeline of tRNA synthetases and NRP2 targeting candidates through internal research efforts, industry and academic collaborations. The impacts of the ongoing COVID-19 pandemic on our business have included the delay in enrollment of our now completed Phase 1b/2a clinical trial in patients with pulmonary sarcoidosis and the discontinuation of some patients in that trial, temporary closures of portions of our facilities and those of our licensees and collaborators, disruptions or restrictions on our employees’ ability to travel and delays in certain research and development activities. Other potential impacts to our business include, but are not limited to disruptions to or delays in other clinical trials, third-party manufacturing supply and other operations, the potential diversion of healthcare resources away from the conduct of clinical trials to focus on pandemic concerns, interruptions or delays in the operations of the FDA or other regulatory authorities, and our ability to raise capital and conduct business development activities.

Liquidity and Capital Resources

We have incurred losses and negative cash flows from operations since our inception. As of December 31, 2021, we had an accumulated deficit of $372.3 million and we expect to continue to incur net losses for the foreseeable future. As of December 31, 2021, we had cash, cash equivalents and available-for-sale investments of $107.9 million. We believe that our current cash, cash equivalents 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. We believe we will meet longer-term material cash requirements from known contractual and other obligations through a combination of cash, cash equivalents and available-for-sale investments. 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 – 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, 2021, our primary sources of cash have been the sale of equity securities, convertible debt, venture debt, term loans and revenues generated through license and collaboration agreement.

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Public Offerings

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

In February 2020, we completed an underwritten follow-on public offering of 4,235,294 shares of our common stock at a price to the public of $4.25 per share. In March 2020, the underwriters fully exercised their over-allotment option for the issuance of an additional 635,294 shares of common stock. The total net proceeds from the offering were approximately $18.8 million, after deducting underwriting discounts, commissions and offering expenses payable by us.

At-the-Market Offering Programs

In March 2021, we entered into a Capital on DemandTM Sales Agreement with JonesTrading Institutional Services LLC (JonesTrading) to create an at-the-market offering (ATM Offering Program) under which we may offer and sell shares of our common stock having an aggregate offering price of up to $25.0 million. JonesTrading is entitled to a commission at a commission rate up to 3% of the gross proceeds. For the year ended December 31, 2021, we sold an aggregate of 986,267 shares of common stock at an average price of $4.75 per share for net proceeds of $4.4 million under the JonesTrading ATM Offering Program.

In May 2019, we entered into a sales agreement with H.C. Wainwright & Co., LLC (Wainwright) for an ATM Offering Program under which we could offer and sell shares of our common stock having an aggregate offering price of up to $10.0 million. In November 2020, we amended our sales agreement with Wainwright to increase the amount of the ATM Offering Program to $20.0 million. Wainwright was entitled to a commission at a fixed commission rate equal to 3% of the gross proceeds. In March 2021, the ATM Offering Program with Wainwright automatically terminated upon the issuance and sale of all of the shares having an aggregate offering price of $20.0 million. Under the ATM Offering Program with Wainwright, during 2020, we sold an aggregate of 1,657,075 shares of common stock at an average price of $4.07 per share for net proceeds of $6.4 million. Prior to the termination of the sales agreement with Wainwright, in 2021, we sold an aggregate of 1,988,254 shares of common stock at an average price of $4.99 per share for net proceeds of $9.6 million.

Purchase Agreement

In September 2020, we entered into a common stock purchase agreement (Purchase Agreement) with Aspire Capital Fund, LLC (Aspire Capital), which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $20.0 million of shares of our common stock at our request from time to time during the 30 month term of the Purchase Agreement. Concurrently with entering into the Purchase Agreement, we also entered into a registration rights agreement with Aspire Capital, in which we agreed to file one or more registration statements, as permissible and necessary to register under the Securities Act of 1933, as amended, for the resale of the shares of our common stock that have been and may be issued to Aspire Capital under the Purchase Agreement. For the year ended December 31, 2021, we sold an aggregate of 3,000,000 shares of common stock at an average price of $5.09 per share for net proceeds of $15.2 million under this Purchase Agreement.

Kyorin Agreement Milestone Payments

We received an $8.0 million upfront payment in January 2020 and a $2.0 million milestone payment in January 2021 upon completion of enrollment in the Phase 1 clinical trial, and we are eligible to receive up to an additional $165.0 million in the aggregate upon achievement of certain development, regulatory and sales milestones, as well as tiered royalties ranging from the mid-single digits to mid-teens on net sales in Japan.

HKUST Grant Agreement

In March 2020, our subsidiary, Pangu BioPharma Limited (Pangu BioPharma), together with the Hong Kong University of Science and Technology (HKUST) was awarded a grant of approximately $750,000 to build a high-throughput platform for the development of bi-specific antibodies. The project is being funded by the Hong Kong government’s Innovation and Technology Commission (ITC) under the Partnership Research Program (PRP). The PRP aims to support research and development projects undertaken by companies in collaboration with local universities and public research institutions. The ITC funded approximately 50% of the total estimated project cost, and we contributed the remaining 50%.

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Cash Flows

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

Operating activities. Net cash used in operating activities was $33.1 million, $15.3 million and $20.1 million for the years ended December 31, 2021, 2020 and 2019, respectively. The net cash used in operating activities in each of these periods was primarily due to our net losses. The primary differences between net cash used in operating activities and our net loss in the year ended December 31, 2021 related to non-cash charges including: $0.5 million for depreciation, $1.6 million for stock-based compensation, $0.8 million for amortization of right-of-use asset, and a $2.6 million increase in our net operating assets and liabilities. The primary differences between net cash used in operating activities and our net loss in the year ended December 31, 2020 related to non-cash charges including: $0.6 million for depreciation, $1.5 million for stock-based compensation, $0.7 million for amortization of right-of-use asset and a $2.3 million increase in our net operating assets and liabilities. The primary differences between net cash used in operating activities and our net loss in the year ended December 31, 2019 related to non-cash charges including: $0.6 million for depreciation, $1.8 million for stock-based compensation, $0.7 million for debt discount accretion and non-cash interest expense, $0.7 million for amortization of right-of-use asset and a $0.2 million decrease in our net operating assets and liabilities.

Investing activities. Net cash provided by (used in) investing activities for the years ended December 31, 2021, 2020 and 2019 was $(91.6) million, $6.9 million and $4.9 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, 2021 was less than two years.

Financing activities. 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 the Purchase Agreement, net of offering costs and $14.1 million proceeds from the ATM Offering Program, net of issuance costs. Net cash provided by financing activities for the year ended December 31, 2020 was $16.1 million and consisted primarily of $18.8 million in proceeds from an underwritten follow-on public offering, net of offering costs, and $6.4 million proceeds from the ATM Offering Program, net of issuance costs, offset in part by $9.1 million of principal payments and final payment on the term loans. Net cash provided by financing activities for the year ended December 31, 2019 was $1.3 million and consisted primarily of $4.4 million in proceeds from the ATM Offering Program, net of issuance costs, and $4.9 million in proceeds from a registered direct offering, net of issuance costs, offset in part by $8.0 million of principal payments on the term loans.

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, including manufacturing and technology transfer activities for efzofitimod, continue IND-enabling studies and manufacturing activities for ATYR2810, continue our research and development activities with respect to other potential therapies based on tRNA synthetase biology and NPR2 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, including:

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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. As a result of the ongoing COVID-19 pandemic and actions taken to slow its spread, the global credit and financial markets have experienced extreme volatility and disruptions, including severely diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates and uncertainty about economic stability. 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, 2021, our material cash requirements from known contractual and other obligations consisted primarily of a non-cancelable facility lease that is subject to base lease payments, which escalate over the term of the lease, additional charges for common area maintenance and other costs. In July 2018, we entered into a lease amendment that reduced the space we lease from 24,494 square feet to 20,508 square feet and extended the lease term to May 2023. With the lease amendment, we do not have an option to extend the lease. As of December 31, 2021, the aggregate present value of the lease payments was $1.4 million of which $1.0 million will be incurred in 2022 and $0.4 million will be incurred in 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, 2021. All intercompany transactions and balances are eliminated in consolidation.

Revenue Recognition

In January 2020, we entered into a collaboration and license agreement with Kyorin for the development and commercialization of efzofitimod for ILD in Japan. Under the Kyorin Agreement, Kyorin received an exclusive right to develop and commercialize efzofitimod in Japan for all forms of ILD. Under the terms of the Kyorin Agreement, Kyorin will fund all research, development, regulatory, marketing and commercialization activities in Japan. In September 2020, Kyorin began dosing of its Phase 1 trial of efzofitimod (known as KRP-R120 in Japan) and completed the last subject visit in December 2020. This achievement triggered a $2.0 million milestone payment, which we received in January 2021. The Phase 1 trial, which was conducted and funded by Kyorin, is a placebo-controlled study to evaluate the safety, PK and immunogenicity of efzofitimod in 32 healthy Japanese male volunteers.

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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. We received an $8.0 million upfront payment and a $2.0 milestone payment and we are eligible to receive an additional $165.0 million in the aggregate upon achievement of certain development, regulatory and sales milestones, as well as tiered royalties ranging from the mid-single digits to mid-teens on net sales in Japan.

For the year ended December 31, 2021, there were no activities that triggered additional license and collaboration agreement revenue while we recognized $10.0 million as license and collaboration agreement revenue for the year ended December 31, 2020 under the Kyorin Agreement.

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 and, more recently research efforts related to NRP2 biology. These expenses consist primarily of:

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, including the costs associated with technology transfer to an additional CDMO of efzofitimod, our preclinical development, planned clinical development and manufacturing of ATYR2810 and other potential therapeutics based on tRNA synthetase biology and NRP2 biology.

We cannot determine with certainty the timing of initiation, the duration or the completion costs of current or future preclinical studies and clinical trials of our product candidates. For instance, as a result of the ongoing COVID-19 pandemic, many clinical trial sites in our completed Phase 1b/2a clinical trial in patients with pulmonary sarcoidosis temporarily suspended dosing of previously-enrolled patients and/or enrollment of new patients and some patients discontinued from the trial.

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

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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. Though the impact of the ongoing COVID-19 pandemic to our business and operating results presents additional uncertainty, we continue to use the best information available to us in our critical accounting estimates.

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, 2021 and 2020

The following table summarizes our results of operations for the years ended December 31, 2021 and 2020 (in thousands):

License and collaboration agreement revenues. Revenues of $10.5 million for the year ended December 31, 2020 consisted primarily of $10.0 million from license and collaboration agreement earned under the Kyorin Agreement.

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Research and development expenses. Research and development expenses were $23.3 million and $17.3 million for the years ended December 31, 2021 and 2020, respectively. The increase of $6.0 million was due primarily to an increase of $6.2 million in product development and manufacturing costs for efzofitimod and ATYR2810, an increase of $1.8 million research development for efzofitimod, ATYR2810 and our discovery programs and an increase of $1.1 million in compensation related expenses. The increase was offset by a decrease of $3.1 million in clinical trial expenses due to the completion of the Phase 1b/2a sarcoidosis clinical trial in September 2021 and the COVID-19 clinical trial in December 2020.

General and administrative expenses. General and administrative expenses were $10.8 million and $9.1 million for the years ended December 31, 2021 and 2020, respectively. The increase of $1.7 million was due primarily to a $1.2 million increase in compensation related expenses, a $0.2 million increase in insurance costs, a $0.2 million increase in professional fees and $0.1 million increase in taxes and licenses.

Other income (expense), net. Other income (expense) was $0.2 million and $(0.3) million for years ended December 31, 2021 and 2020, respectively. The change was primarily a result of a reduction in interest expense due to the repayment of our term loans in November 2020.

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.