On December 8, 2025 MaaT Pharma (EURONEXT: MAAT – the "Company"), a clinical-stage biotechnology company and a leader in the development of Microbiome Ecosystem TherapiesTM (MET) dedicated to enhancing survival for patients with cancer through immune modulation, reported that Prof. Malard, MD, PhD, hematology professor at Saint-Antoine Hospital and Sorbonne University and ARES Trial lead investigator, presented the results for the pivotal ARES, single arm, open label trial evaluating MaaT013 (Xervyteg) in aGvHD during an oral session at the 67th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting and Exposition currently taking place in Orlando, Florida, USA. In addition, the Company announced new data from the pivotal ARES trial including a 1-year overall survival rate of 54%, confirming the global clinical benefit of MaaT013 (Xervyteg).

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"These results confirm that MaaT013 (Xervyteg) offers a durable clinical benefit for patients with GI-aGvHD who have exhausted all currently approved treatment options. Achieving a 62% gastrointestinal response at Day 28, maintaining responses over time, and reaching a 54% one-year overall survival represent a meaningful step forward in addressing this critical unmet need," said Prof. Florent Malard, MD, PhD, Professor of Hematology at Saint-Antoine Hospital and Sorbonne University, and lead investigator of the ARES trial who presented the findings.

Prof. Malard detailed primary and secondary endpoints, noting that GI-Overall Response Rate (GI-ORR) at Day 28 (62% including 38% of complete response) remains high over time, indicating a durable response with a GI-ORR of 47% and all-organ ORR of 45% at Day 56. At three months, GI-ORR and all-organ ORR were both still high at 44%. These results indicate that responses to MaaT013 (Xervyteg) are durable and result in improved survival outcomes, which translates into a 54% 1-year overall survival rate in the study population.

Final efficacy data of MaaT013 (Xervyteg) in the ARES study are summarized below.
The ARES trial is a single-arm, open label trial evaluating MaaT013 (Xervyteg) as third-line treatment in 66 adult patients with severe GI-aGvHD refractory to corticosteroids and ruxolitinib across 50 sites in six European countries:

Patient profile:

91% (n=60) presented with Grade III–IV aGvHD with GI involvement
86% (n=57) were steroid-resistant and 14% (n=9) steroid-dependent; all were refractory to ruxolitinib
Male: 53%, Female: 47%
Final results:

GI-ORR at Day 28 occurred in 41/66 patients (62%) and prevalently consisted of complete response (CR) (38%, 25/66 patients), and very good partial response (VGPR) (20%, 13/66 patients).
All-organ ORR at Day 28 occurred in 42/66 patients (64%) patients and was similarly driven by high rates of CR (36%, 24/66 patients) and VGPR (18%, 12/66 patients).
GI-ORR at Day 56 was maintained at 47% (31/ 66 patients) and prevalently consisted of CR (35%, 23/66 patients).
All-organ ORR at Day 56 was 45% (30/66 patients) and prevalently consisted of CR (35%, 23/66 patients).
GI-ORR and all-organ ORR at 3 months were both 44% (29/ 66 patients), with a prevalence of CR (36%, 24/66 patients).
Overall survival (OS) at 12 months was 54% (median survival not reached), this confirms the 12-month probability of survival of 54% announced in January 2025 for the topline results.
Median overall survival was not reached, indicating that more than half of the patients were still alive at the end of the study. This suggests a durable survival benefit and reinforces the strong efficacy signal observed in the pivotal ARES study. The median OS of responders was not reached, while it was only 54 days for non-responders.
The OS was significantly higher in patients who had a GI response at Day 28 than those who did not respond: 68% vs 28% respectively (p <0.0001), indicating a strong association between early GI response and improved survival in refractory GI-aGvHD.
Safety data showed that MaaT013 (Xervyteg) was associated with an acceptable tolerability profile in severe aGvHD patient population (as reviewed continuously by a Data and Safety Monitoring Board).
The pivotal ARES trial results will soon be submitted for publication in a leading peer-reviewed medical journal. MaaT013 (Xervyteg) is currently under review by the European Medicines Agency (EMA) following the submission of a marketing authorization application in June 2025, with a decision expected in mid- 2026, as previously announced. If approved, MaaT013 (Xervyteg) would become the first microbiotherapy in oncology in the world and the first 3rd line therapy in aGvHD addressing a critical unmet need.

(Press release, MaaT Pharma, DEC 8, 2025, View Source [SID1234661265])