MaaT013 in steroid-refractory and steroid-dependent GI-aGvHD: Outcomes from an early access program and the phase III ARES trial

Patients with steroid-refractory (SR) or steroid-dependent (SD) gastrointestinal (GI) aGvHD – particularly those for whom ruxolitinib therapy has failed – have limited treatment options and poor survival outcomes, highlighting a critical unmet need. GI involvement is especially challenging to manage, and fecal microbiotherapy has shown potential by restoring microbiome diversity and modulating immune responses.

MaaT013 is a standardized, pooled allogeneic microbiota product designed to address this need, without contributing additional immunosuppression. At the European Hematology Association (EHA) 2025 Congress, Mohamad Mohty presented outcomes from 173 patients with refractory GI-aGvHD treated with MaaT013 across 27 sites in Europe between July 2018 and October 2024 through an early access program (EAP). Response was calculated comparing aGvHD grading at Day 28 vs at baseline. Mohty also discussed top-line findings from the ongoing phase III ARES trial (NCT04769895), which is evaluating MaaT013 in third-line settings for patients whose GvHD is refractory to both corticosteroids and ruxolitinib (N = 66), with a primary endpoint of GI ORR at Day 26.¹

Key learnings²

In the EAP, GI-ORR was 53% at Day 28, with 30% achieving CR and 16% VGPR. At Day 56, GI-ORR was 47% (CR: 34%, VGPR: 10%). 12-month OS was higher in Day 28 responders (69%) vs non-responders (25%).

In patients with ruxolitinib-refractory GI-aGvHD (n = 70), GI-ORR was 57% at Day 28 and Day 56, with CR increasing from 44% at Day 28 to 51% at Day 56. 12-month OS was 77% in responders vs 14% in non-responders.

The ARES trial met its primary endpoint, with a significant GI-ORR of 62% at Day 28 (p < 0.0001), including 58% of patients achieving CR or VGPR. 12-month OS was 67% in Day 28 responders vs 28% in non-responders. 

MaaT013 offers a potential microbiota-based treatment for SR/SD GI-aGvHD, with consistent efficacy, durable responses, favorable survival outcomes, and a favorable safety profile across real-world and clinical trial settings, supporting its role in this high-risk, treatment-refractory population.