Astria Reports Positive Phase 1a Data for STAR-0310, a Long-Acting OX40 Antagonist

Astria Therapeutics recently announced positive initial results from the phase 1a trial of STAR-0310, a YTE half-life extended monoclonal antibody antagonist of OX40, in healthy patients. Astria reported that 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.”¹

Based on the early results, STAR-0310 could be a new, novel OX40 antagonist.

Stephan Weidinger, MD, PhD, director and chair of the department of dermatology and allergy at the University Medical Center Kiel, Schleswig-Holstein, will present the 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 the European Academy of Dermatology and Venereology (EADV) Congress 2025.

“The Phase 1a healthy participant initial results of STAR-0310 demonstrate a compelling early differentiation story for the program,” said Christopher Morabito, MD, Chief Medical Officer at Astria Therapeutics, in the news release. “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 was observed to be well-tolerated, with no serious treatment-emergent adverse events (TEAEs) or discontinuations. The company noted that mild, treatment-related TEAEs were observed in 7 participants receiving STAR-0310 that resolved without intervention. No fever or chills were observed, which is consistent with the preclinical observation that STAR-0310 exhibits low ADCC activity.

Biomarker findings showed that one 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. The data support strong target engagement and indicate that STAR-0310 modulates multiple immune pathways beyond Th2 for a prolonged duration, with the potential to benefit a wider patient population than currently approved biologics.

Astria stated that it plans to share an update on plans for STAR-0310’s development in the upcoming months.

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 4 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).

Reference

1. Astria Therapeutics announces positive initial results from the phase 1a healthy subject trial of STAR-0310 at the European Academy of Dermatology and Venereology. News release. Business Wire. September 17, 2025. Accessed September 19, 2025. https://www.businesswire.com/news/home/20250917815272/en/Astria-Therapeutics-Announces-Positive-Initial-Results-from-the-Phase-1a-Healthy-Subject-Trial-of-STAR-0310-at-the-European-Academy-of-Dermatology-and-Venereology