IMMEDIATE RELEASE Contact: Joyce Allaire Managing Director, LifeSci Advisors, LLC jallaire@lifesciadvisors.com aTyr Pharma Announces First Quarter 2019 Results and Provides Corporate Update Phase 1b/2a proof-of-concept c

aTyr Pharma Announces First Quarter 2019 Results and Provides Corporate Update

Phase 1b/2a proof-of-concept clinical trial of ATYR1923 in pulmonary sarcoidosis patients ongoing

Advanced lead position in Neuropilin-2 (NRP-2) biology with inaugural NRP-2 summit

Company to host conference call and webcast today at 5:00pm EDT / 2:00 PDT

SAN DIEGO - May 13, 2019 - aTyr Pharma, Inc. (Nasdaq: LIFE), a biotherapeutics company engaged in the discovery and development of innovative medicines based on novel immunological pathways, today announced first quarter 2019 results and provided a corporate update.

"During the first quarter, we continued to execute on our Phase 1b/2a study of our lead therapeutic candidate, ATYR1923, a selective NRP-2 inhibitor, in patients with pulmonary sarcoidosis, and we look forward to reporting interim results in the fourth quarter of this year," said Dr. Sanjay Shukla, President and Chief Executive Officer of aTyr. "At the same time, we continued to advance our understanding of the emerging role of NRP-2 in the modulation of immune responses. We recently held an inaugural summit meeting of leading experts in the field of NRP-2 biology to discuss the down-regulation of the innate and adaptive immune systems and potential clinical utility across a broad range of inflammatory disease states."

First Quarter 2019 and Subsequent Period Highlights

First Quarter 2019 Financial Results and Cash Position

Research and development expenses were $3.3 million and $6.2 million for the three months ended March 31, 2019 and 2018, respectively. General and administrative expenses were $2.5 million and $4.1 million for the three months ended March 31, 2019 and 2018, respectively. The decreases for both research and development expenses and general and administrative expenses were primarily related to the Company's corporate restructuring announced in May 2018, where aTyr announced its focused development efforts on the clinical advancement of ATYR1923 along with related reductions in headcount and personnel-related costs and other cost saving measures.

As of March 31, 2019, aTyr had $43.0 million in cash, cash equivalents and investments. Subsequent to the end of the quarter, the Company raised $5.0 million in gross proceeds through a registered direct investment led by Federated Kaufmann Small Cap Fund.

Conference Call and Webcast Details

aTyr Pharma will host a conference call and webcast today at 5:00 p.m. Eastern Time / 2:00 p.m. Pacific Time to discuss its financial results and provide a corporate update. Interested parties may access the call by dialing toll-free (844) 358-9116 from the US, or (209) 905-5951 internationally, and using conference ID 4868007. Links to a live audio webcast and replay may be accessed on the aTyr website events page at: http://investors.atyrpharma.com/events-and-webcasts. An audio replay will be available for at least 90 days following the event.

aTyr is developing ATYR1923 as a potential therapeutic for patients with interstitial lung diseases. ATYR1923, a fusion protein comprised of the immuno-modulatory domain of histidyl tRNA synthetase (HARS) fused to the FC region of a human antibody, is a selective modulator of Neuropilin-2 that downregulates the innate and adaptive immune response in inflammatory disease states. aTyr initiated a proof-of-concept Phase 1b/2a trial evaluating ATYR1923 in patients with pulmonary sarcoidosis in the fourth quarter of 2018. This Phase 1b/2a study is a multi-ascending dose, placebo-controlled, first-in-patient study of ATYR1923 that has been designed to evaluate the safety, tolerability, steroid sparing effect, immunogenicity and pharmacokinetics (PK) profile of multiple doses of ATYR1923. For the Phase 1b/2a trial, aTyr is collaborating with the Foundation for Sarcoidosis Research (FSR), the nation's leading nonprofit organization dedicated to finding a cure for sarcoidosis and improving care for sarcoidosis patients. Under the terms of the collaboration, FSR will assist with clinical trial site initiation and patient enrollment.

aTyr is a biotherapeutics company engaged in the discovery and development of innovative medicines based on novel immunological pathways. aTyr's research and development efforts are concentrated on a newly discovered area of biology, the extracellular functionality of tRNA synthetases. aTyr has built a global intellectual property estate directed to a potential pipeline of protein compositions derived from 20 tRNA synthetase genes. aTyr is focused on the therapeutic translation of the Resokine pathway, comprised of extracellular proteins derived from the histidyl tRNA synthetase gene family. ATYR1923 is a clinical-stage product candidate which binds to the neuropilin-2 receptor and is designed to down-regulate immune engagement in interstitial lung diseases and other immune-mediated diseases. For more information, please visit http://www.atyrpharma.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Litigation Reform Act. Forward-looking statements are usually identified by the use of words such as "anticipates," "believes," "estimates," "expects," "intends," "may," "plans," "projects," "seeks," "should," "will," and variations of such words or similar expressions. We intend these forward-looking statements to be covered by such safe harbor provisions

for forward-looking statements and are making this statement for purposes of complying with those safe harbor provisions. These forward-looking statements, including statements regarding our projected cash expenditures, the potential therapeutic benefits and applications of our product candidates; our ability to successfully advance our product candidates, undertake certain development activities (such as the initiation of clinical trials, clinical trial enrollment, the conduct of clinical trials and the announcement of top-line results) and accomplish certain development goals, and the timing of such events; and the scope and strength of our intellectual property portfolio. These forward-looking statements also reflect our current views about our plans, intentions, expectations, strategies and prospects, which are based on the information currently available to us and on assumptions we have made. Although we believe that our plans, intentions, expectations, strategies and prospects, as reflected in or suggested by these forward-looking statements, are reasonable, we can give no assurance that the plans, intentions, expectations or strategies will be attained or achieved. All forward-looking statements are based on estimates and assumptions by our management that, although we believe to be reasonable, are inherently uncertain. Furthermore, actual results may differ materially from those described in these forward-looking statements and will be affected by a variety of risks and factors that are beyond our control including, without limitation, risks associated with the discovery, development and regulation of our product candidates, the risk that we may cease or delay preclinical or clinical development activities for any of our existing or future product candidates for a variety of reasons (including difficulties or delays in patient enrollment in current and planned clinical trials), and the risk that we may not be able to raise the additional funding required for our business and product development plans, as well as those risks set forth in our most recent Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and in our other SEC filings. Except as required by law, we assume no obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise.