Intel Appoints Dr. Craig H. Barratt to Board of Directors

-- Results Support Potential for STAR-0310 to be Best-in-Class OX40 Antagonist --

-- STAR-0310 Exhibits Longest-in-Class Half-Life of 68 Days and Cytokine Suppression Lasting At Least 20 Weeks After a Single 300 mg SC Injection, Supporting Potential Every-Six-Month Administration --

-- STAR-0310 Was Well-Tolerated, with no ADCC-Related Treatment-Emergent Adverse Events, Supporting a Wider Therapeutic Window with the Potential to Drive Greater Efficacy than First-Generation OX40 Antibodies --

-- Results to be Presented by Dr. Stephan Weidinger, M.D., Ph.D. on September 18, at 4:00pm CEST --

BOSTON--(BUSINESS WIRE)-- Astria Therapeutics, Inc. (NASDAQ:ATXS), a biopharmaceutical company focused on developing life-changing therapies for allergic and immunologic diseases, today announced positive initial results from the Phase 1a trial of STAR-0310, a YTE half-life extended monoclonal antibody antagonist of OX40, in healthy subjects. STAR-0310 demonstrated a best-in-class half-life of up to 68 days, consistent with administration every six months, durable cytokine inhibition, and was well-tolerated with no antibody-dependent cellular cytotoxicity (ADCC)-related side effects. Based on these results, STAR-0310 has the potential to be the best-in-class OX40 antagonist.

Dr. Stephan Weidinger, M.D., Ph.D., Director and Chair of the Department of Dermatology and Allergy at the University Medical Center Kiel, Schleswig-Holstein, will present these results in a late-breaking oral presentation titled “Demonstration of Early Proof-of-Concept for STAR-0310, a Long-Acting OX40 Receptor Antagonist: Initial Safety, PK, and PD Results from a Phase 1a Trial” at 4:00pm CEST on September 18 in the Paris Nord room at the European Academy of Dermatology and Venereology Congress.

“The Phase 1a healthy participant initial results of STAR-0310 demonstrate a compelling early differentiation story for the program,” said Christopher Morabito, M.D., Chief Medical Officer at Astria Therapeutics. “Importantly, we observed no fever and chills while seeing rapid and sustained target engagement and durable pharmacodynamic effects, demonstrating that STAR-0310 has the potential to drive greater efficacy without dose-limiting ADCC-related side effects seen in first-generation OX40 antagonists. Additionally, based on these Phase 1a results, STAR-0310’s half-life is the longest of any investigational OX40/OX40L antibody, supporting the potential for infrequent, every six-month administration with a low treatment burden. We believe that STAR-0310 could have a wider therapeutic window than other OX40 therapies that could potentially drive differentiated lasting efficacy for people living with atopic dermatitis, particularly the significant portion of patients who do not respond to existing biologics like Dupixent.”

STAR-0310 exhibited dose-proportional increases in concentrations, with slow clearance and an extended half-life of up to 68 days.

STAR-0310 was observed to be well-tolerated at all dose levels, with no serious treatment-emergent adverse events (TEAEs) or discontinuations. Mild, treatment-related TEAEs were observed in seven participants receiving STAR-0310 that resolved without intervention. No fever or chills were observed, consistent with the preclinical observation that STAR-0310 exhibits low ADCC activity.

Biomarker results showed that a single, subcutaneous injection of STAR-0310 resulted in sustained and durable ex vivo cytokine inhibition (IL-2, IL-22, IL-31, IL-4) for the duration of the observation period of 16 to 20 weeks, supporting robust target engagement and suggesting that STAR-0310 is modulating a broad spectrum of immune pathways beyond Th-2 for a long duration of effect, and could benefit a broader patient population than existing approved biologics.

The Phase 1a trial of STAR-0310 is a randomized, double-blind, placebo-controlled single ascending dose trial evaluating the safety, tolerability, pharmacokinetics, and immunogenicity of STAR-0310 in 32 adults. Participants were randomized to receive a single subcutaneous dose of STAR-0310 or placebo across four dose cohorts: 150 mg, 300 mg, 600 mg, and 1200 mg. This interim analysis includes available safety, PK and PD data from all cohorts through the following follow-up windows: Day 168 for Cohort 1 (150 mg), Day 140 for Cohort 2 (300 mg), Day 112 for Cohort 3 (600 mg), and Day 84 for Cohort 4 (1200 mg). The Company plans to share an update on plans for STAR-0310’s development in the coming months.

About Astria Therapeutics:

Astria Therapeutics is a biopharmaceutical company, and our mission is to bring life-changing therapies to patients and families affected by allergic and immunologic diseases. Our lead program, navenibart (STAR-0215), is a monoclonal antibody inhibitor of plasma kallikrein in clinical development for the treatment of hereditary angioedema. Our second program, STAR-0310, is a monoclonal antibody OX40 antagonist in clinical development for the treatment of atopic dermatitis. Learn more about our company on our website, www.astriatx.com, or follow us on Instagram @AstriaTx and on Facebook and LinkedIn.

Forward Looking Statements:

This press release contains forward-looking statements within the meaning of applicable securities laws and regulations including, but not limited to, statements regarding: the significance of the initial results from the Phase 1a trial of STAR-0310, including the potential for STAR-0310 to be the best overall OX40 antagonist, with a favorable safety and tolerability profile, administration as infrequently as every 6 months and potential for strong efficacy; our plans to share an update on STAR-0310 development; and our corporate strategy and vision, including our mission is to bring life-changing therapies to patients and families affected by allergic and immunologic diseases; and statements about the Company’s current operating plan and cash runway. The use of words such as, but not limited to, “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “goals,” “intend,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will,” “would,” or "vision," and similar words expressions are intended to identify forward-looking statements. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on Astria’s current beliefs, expectations and assumptions regarding the future of its business, future plans and strategies, future financial performance, results of pre-clinical and clinical results of the Astria’s product candidates and other future conditions. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including risks and uncertainties related to: changes in applicable laws or regulations; the possibility that we may be adversely affected by other economic, business, and/or competitive factors; risks inherent in pharmaceutical research and development, such as: adverse results in our drug discovery, preclinical and clinical development activities, the risk that the results of preclinical studies may not be replicated in clinical trials, that the preliminary, initial or interim results from clinical trials may not be indicative of the final results, that the results of early stage clinical trials, such as the results from the ALPHA-STAR Phase 1b/2 clinical trial and the initial results from the STAR-0310 Phase 1a trial, may not be replicated in later stage clinical trials, such as navenibart Phase 3 development program, the risk that we may not be able to enroll sufficient patients in our clinical trials on a timely basis, and the risk that any of our clinical trials may not commence, continue or be completed on time, or at all; decisions made by, and feedback received from, the U.S. Food and Drug Administration and other regulatory authorities on our regulatory and clinical trial submissions and other feedback from potential clinical trial sites, including investigational review boards at such sites, and other review bodies with respect to navenibart, STAR-0310, and any other future development candidates; our ability to manufacture sufficient quantities of drug substance and drug product for navenibart, STAR-0310, and any other future product candidates on a cost-effective and timely basis, and to develop dosages and formulations for navenibart, STAR-0310, and any other future product candidates that are patient-friendly and competitive; our ability to develop biomarker and other assays, along with the testing protocols therefor; our ability to obtain, maintain and enforce intellectual property rights for navenibart, STAR-0310 and any other future product candidates; our potential dependence on collaboration partners; competition with respect to navenibart, STAR-0310, or any of our other future product candidates; the risk that survey results, modeling data and market research may not be accurate predictors of the commercial landscape for HAE, the ability of navenibart to compete in HAE and the anticipated position and attributes of navenibart in HAE based on clinical data to date, its preclinical profile, pharmacokinetic modeling, market research and other data; risks that any of our clinical trials of STAR-0310 may not commence, continue or be completed on time, or at all; risks that results of preclinical studies of STAR-0310 will not be replicated in clinical trials; our ability to manage our cash usage and the possibility of unexpected cash expenditures; our ability to obtain necessary financing to conduct our planned activities, including the costs associated with commercializing navenibart if regulatory approval is obtained, and to manage unplanned cash requirements; the risks and uncertainties related to our ability to recognize the benefits of any additional acquisitions, licenses or similar transactions; and general economic and market conditions; as well as the risks and uncertainties discussed in the “Risk Factors” sections of our Annual Report on Form 10-K for the period ended December 31, 2024 and our Quarterly Report for the period ended June 30, 2025, and in other filings that we may make with the Securities and Exchange Commission. New risks and uncertainties may emerge from time to time, and it is not possible to predict all risks and uncertainties. Astria may not actually achieve the forecasts or expectations disclosed in our forward-looking statements, and investors and potential investors should not place undue reliance on Astria’s forward-looking statements.

Neither Astria, nor its affiliates, advisors or representatives, undertake any obligation to publicly update or revise any forward-looking statement, whether as result of new information, future events or otherwise, except as required by law. These forward-looking statements should not be relied upon as representing Astria’s views as of any date subsequent to the date hereof.

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Astria Contact:

Investor Relations and Media:

Elizabeth Higgins

investors@astriatx.com

Source: Astria Therapeutics, Inc.