Final results from the Phase 3 ARES trial, presented at the EBMT 52nd Annual Meeting, show that the fecal microbiotherapy MaaT013 significantly improves survival for patients with life-threatening, drug-resistant gut graft-versus-host disease (aGVHD).
Patients with gastrointestinal aGVHD who fail steroids and ruxolitinib usually face a median survival of about 86 days. In the trial, MaaT013—a high-diversity mix of healthy gut bacteria—achieved a 62.1% overall response rate within 28 days and complete symptom disappearance in 38% of patients. At 12 months, overall survival reached 54%, far above the ~15% typically seen in this group.
MaaT013 is administered as a 150-mL rectal enema on Days 1, 5, and 10, after vancomycin pretreatment to prepare the gut. Safety monitoring showed infections were common, reflecting the vulnerable patient population, but only 12% experienced serious adverse events directly related to the therapy.
This therapy offers a promising new approach for patients with limited options, repairing the gut microbiome and substantially improving survival.