MaaT Pharma Announces Positive Phase 3 Results Evaluating Xervyteg® (MaaT013) in Acute Graft-versus-Host Disease Selected for Oral Presentation at ASH Congress 2025

MaaT Pharma, a clinical-stage biotechnology company and a leader in the development of Microbiome Ecosystem Therapies^TM (MET) dedicated to enhancing survival for patients with cancer through immune modulation, today announced that results from its pivotal Phase 3 ARES trial evaluating Xervyteg^® (MaaT013) in patients with gastrointestinal acute Graft-versus-Host Disease refractory to steroids and refractory or intolerant to ruxolitinib (SR GI-aGvHD) will be presented in an oral session at the 67^th American Society of Hematology (ASH) Annual Meeting and Exposition that will take place December 6-9, 2025, in Orlando, Florida, USA. This marks the ninth consecutive year that MaaT Pharma’s clinical data has been selected for presentation at ASH annual meeting, and the first time the Company will present its Phase 3 results at a medical congress.

“For the ninth consecutive year, MaaT Pharma is proud to present data at ASH, reaffirming our position as the undisputed leader in microbiotherapy for hematology-oncology. The ARES study demonstrated a clinically meaningful and durable benefit in patients with gastrointestinal aGvHD, further validating our approach and its potential to redefine the standard of care in this high unmet need,” said Hervé Affagard, CEO and co-founder of MaaT Pharma.

The ARES trial met its primary endpoint and topline results were announced in January 2025.  At the upcoming ASH annual meeting, the Company will detail secondary endpoints, such as GI-ORR at D56 and Month 3 (M3), and some safety data. Final results, including 1-year overall survival, are expected by the end of 2025.

In the single-arm ARES study, 66 adult patients with GI-aGvHD refractory to steroids and refractory to ruxolitinib were treated with Xervyteg^® (MaaT013) as third-line treatment across 50 European sites in 6 countries (Austria, Belgium, France, Germany, Italy and Spain). The vast majority of patients included in the study (91%, n=60) presented with severe gastrointestinal aGvHD, classified as grade III (58%, n=38) or grade IV (33%, n=22). Among them, 86% (n=57) were steroid-resistant and 14% (n=9) steroid-dependent; all were refractory to ruxolitinib.

Efficacy data to be presented at the ASH annual meeting is summarized below (see here for full abstract) – (up to the data cut-off of November 11, 2024):

• GI-Overall Response Rate at Day 28 occurred in 41/66 patients (62%) and prevalently consisted of complete response (CR) (25/66 patients, 38%) and very good partial response (VGPR) (13/66 patients, 20%).
• Overall Response Rate (all organs) at Day 28 occurred in 42/66 patients (64%) patients and was similarly driven by high rates of CR (24/66 patients, 36%) and VGPR (12/66 patients, 18%).
• GI-ORR at Day 56 was maintained in 49% (31/ 63 patients) and prevalently consisted of CR (37%).
• GI-ORR at 3 months was 44% (27/ 62 patients), with a prevalence of GI-CR (36%).
• Average duration of response was 6.4 months.
• Probability of overall survival (OS) at 12 months:
  • The estimated OS was 54% with a median follow-up of 140.5 days (median survival not reached).
  • The estimated OS was significantly higher in patients who had a GI response at Day 28 than those who did not respond (67% vs 28% respectively, p <0.0001), demonstrating Xervyteg^® (MaaT013)’s significant survival benefit in refractory GI-aGvHD.
  • The median OS of responders was not reached while it was 54 days in non-responders.

Xervyteg^® (MaaT013) is currently under review by the European Medicines Agency (EMA) following the submission of a Marketing Authorization Application in June 2025, with a decision anticipated in the second half of 2026.

Details of the Oral Presentation:

• Title: MaaT013 for ruxolitinib-refractory acute graft-versus-host disease with gastrointestinal involvement: Results from the ARES phase III trial
• Publication Number: 817
• Presenting Author: Prof. Malard, MD, hematology professor at Saint-Antoine Hospital and Sorbonne University, lead investigator for the Phase 3 ARES trial
• Session Date: December 8, 2025
• Presentation Time: 10:30 AM – 10:45 AM
• Session Name: 722. Allogeneic Transplantation: Acute and Chronic GVHD and Immune Reconstitution: Clinical and Translational Insights
• Room: OCCC – Sunburst Room (W340)

Upcoming investor and medical conferences participation

• November 5-9, 2025 – 40^th SITC annual meeting in National Harbor, MD, USA
• November 19-21, 2025 – SFGM-TC annual meeting in Geneva, Switzerland
• November 25, 2025 – Investir Day event, Paris, France
• December 6-9, 2025 – 67^th ASH annual meeting in Orlando, FL, USA

For the latest updates and in-depth insights into the world of Pharmaceuticals, including breakthrough treatments, industry trends, and regulatory news, contact Sophie Andrews today!