Orlando, Florida — December 8, 2025 — Leads & Copy —
MaaT Pharma, a clinical-stage biotechnology company, announced that Prof. Malard, MD, PhD, presented results from the pivotal ARES trial evaluating MaaT013 (Xervyteg®) in acute Graft-versus-Host Disease (aGvHD) at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition in Orlando, Florida. The Company also announced new data from the ARES trial, including a one-year overall survival rate of 54%.
Prof. Florent Malard, MD, PhD, Professor of Hematology at Saint-Antoine Hospital and Sorbonne University, the lead investigator of the ARES trial stated that MaaT013 (Xervyteg®) offers a durable clinical benefit for patients with GI-aGvHD who have exhausted all approved treatment options. He noted the 62% gastrointestinal response at Day 28, maintained responses over time, and a 54% one-year overall survival as a meaningful step forward in addressing this unmet need.
Prof. Malard detailed primary and secondary endpoints, noting that the GI-Overall Response Rate (GI-ORR) at Day 28 (62%, including 38% complete response) remained high over time. The GI-ORR was 47% and all-organ ORR was 45% at Day 56.
At three months, GI-ORR and all-organ ORR were both 44%. These results indicate that responses to MaaT013 (Xervyteg®) are durable and result in improved survival outcomes, with a 54% one-year overall survival rate in the study population.
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. Key data from the study includes:
- 91% (n=60) of patients 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.
- 53% of patients were male, and 47% were female.
Final results from the study include:
- GI-ORR at Day 28 occurred in 41/66 patients (62%), consisting 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%), 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 consisted of CR (35%, 23/66 patients).
- All-organ ORR at Day 56 was 45% (30/66 patients) and 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), confirming the 12-month probability of survival 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. The median OS of responders was not reached, while it was 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).
Safety data showed that MaaT013 (Xervyteg®) was associated with an acceptable tolerability profile in severe aGvHD patient population.
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.
If approved, MaaT013 (Xervyteg®) would become the first microbiotherapy in oncology and the first 3rd-line therapy in aGvHD.
MaaT Pharma is focused on developing innovative gut microbiome-driven therapies to modulate the immune system and enhance cancer patient survival. The Company was founded in 2014 and is based in Lyon, France. MaaT Pharma has been listed on Euronext Paris (ticker: MAAT) since 2021.
Acute Graft-versus-Host Disease (aGvHD) occurs in patients within 100 days of undergoing a stem cell or bone marrow transplant, where the transplanted cells initiate an immune response and attack the transplant recipient’s organs. The standard first line therapy for treating aGvHD is the use of systemic steroids. Currently, the second-line treatment for steroid-refractory acute graft-versus-host disease (SR aGvHD) is ruxolitinib and remestemcel—L-rknd was approved in December 2024 in the US specifically for use in the paediatric population as a second-line treatment.
MaaT Pharma’s Microbiome Ecosystem Therapies (MET) are designed to leverage a full microbiome ecosystem to restore balance and maximize clinical benefits for patients with severe, treatment-induced dysbiosis in acute diseases. Xervyteg® (MaaT013) aims to restore the symbiotic relationship between the patient’s functional gut microbiome and their immune system to correct the responsiveness and tolerance of immune functions and thus reduce steroid-resistant, gastrointestinal (GI)-aGvHD. Xervyteg® (MaaT013) has been granted Orphan Drug Designation by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).
Source: MaaT Pharma
