MaaT013 (Xervyteg®): Positive Results from the Pivotal Study in Acute
Graft-vs-Host Disease

Inclusion criteria:

  • Age ≥ 18 years old
  • Allo-HSCT with any type of donor, stem cell source, GvHD prophylaxis or conditioning regimen
  • Patients who develop aGvHD episode with GI involvement per MAGIC guidelines (=grades II to IV), with or without involvement of other organs (Harris et al. 2016)
  • Patients resistant to steroids AND either resistant to OR with intolerance to ruxolitinib (intolerant patients: who had grade 3 or higher treatment-emergent and ruxolitinib-attributed adverse event that did not resolve within 7 days of discontinuing ruxolitinib). The diagnosis must be confirmed within 48h prior to study pre-treatment start.


The study was conducted in 6 European countries (Austria, Belgium, France,Germany, Italy and Spain) accross 50 sites.

ARES: Strong Response to MaaT013 (Xervyteg®) in aGvHD Following Steroid and Ruxolitinib Failure

  • 62% GI-ORR with high CR and VGPR rates.

  • 64% ORR indicating efficacy beyond the GI tract.

  • Day 56: Durable efficacy with GI-ORR 47% and all-organ ORR 45%.
  • Month 3: GI-ORR and all-organ ORR both at 44%, confirming sustained response.

MaaT013 (Xervyteg®) achieves a 54% 1‑year OS, outperforming expectations, whereas the contemporaneous European CHRONOS1 cohort with ARES overlapping centers and inclusion aligned criteria reported 29% survival at EBMT Congress 2026 and published in BMT journal, with retrospective design considerations.

1: 3rd-line with aligned eligibility. Non-randomized, non-matched; descriptive only – CHRONOS STUDY – Clausen et al., BMT 2026

“These results confirm that MaaT013 offers a durable clinical benefit for patients with GI-aGvHD. Achieving a 62% GI-ORR 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.”

Prof. Malard, MD, hematology professor at Saint-Antoine Hospital and Sorbonne University, lead investigator for the ARES pivotal trial

 

📰 MaaT013 (Xervyteg®) is currently under evaluation by the European Medicines Agency (EMA) following the submission of a Marketing Authorization Application in June, for the treatment of adult patients with aGvHD, including gastrointestinal involvement, who have received two prior lines of therapy.

 

  • 1SR-GI-aGvHD in ARES Study is defined as patients resistant to steroids AND either resistant to OR with intolerance to ruxolitinib (intolerant patients: who had grade 3 or higher treatment-emergent and ruxolitinib-attributed adverse event that did not resolve within 7 days of discontinuing ruxolitinib). SR-aGvHD includes patients administered high-dose systemic CS (methylprednisolone 2 mg/kg/day – or equivalent prednisone dose 2.5 mg/kg/day), given alone or combined with CNI or mTOR inhibitor and either:
    • Lack of improvement (i.e., no decrease in stage in at least 1 involved organ system) after ≥ 5 days of treatment with CS at 2 mg/Kg/d methylprednisolone equivalent dose, or
    • Progression (i.e., increase in any organ system or any new organ involvement) after ≥ 3 days of treatment with CS at 2 mg/Kg/d methylprednisolone equivalent dose, or
    • Patients treated with 1 mg/Kg/d of CS because the physician deemed that they would not tolerate 2 mg/Kg/d and who correspond to the definition of SR patients, or
    • Patients who previously began CS therapy at a lower dose (at least 1 mg/Kg/d methylprednisolone equivalent) but develop new GvHD in another organ system, or
    • Patients who cannot tolerate CS tapering, i.e., begin CS at 2.0 mg/Kg/d, demonstrate response, but show disease progress before a 50% decrease from the initial starting dose of CS is achieved.
  • Resistance to ruxolitinib is defined as any of the following (Mohty M. 2020):
    • Progression of GvHD compared to baseline after at least 5 days of treatment with ruxolitinib, based either on objective increase in stage/grade, or new organ involvement, or
    • Lack of improvement in GvHD (partial response or better) compared to baseline after at least 14 days of treatment with ruxolitinib, or
    • Loss of response, defined as objective worsening of GvHD determined by increase in stage, grade or new organ involvement at any time after initial improvement, or
    • Absence of complete response or very good partial response at day 28 after ruxolitinib.
  • Intolerance to ruxolitinib is defined as GvHD manifestations persisting without improvement in patients who had grade 3 or higher treatment-emergent and ruxolitinib-attributed adverse event that did not resolve within 7 days of discontinuing ruxolitinib.
  • aGVHD: acute graft-versus-host disease
  • GI:gastrointestinal
  • MAGIC: Mount Sinai Acute GVHD International Consortium
  • ORR: overall response rate
  • SR: steroid-refractory
  • D: Day
  • M: Month

Acting Chief Scientific Officer

Sheri Simmons

Sheri Simmons, Ph.D., is Acting Chief Scientific Officer at MaaT Pharma. Sheri brings extensive experience in biotechnology, particularly in the microbiome field, having held scientific leadership positions at Seres Therapeutics, Johnson & Johnson’s Microbiome Solutions team, and most recently at Seed Health, a leading probiotics company. In her role, she strengthens the Company’s scientific leadership, overseeing preclinical research, AI/data initiatives, and supporting efforts toward the Marketing Authorization Application of Xervyteg® in aGvHD.

Sheri holds a PhD in Biological Oceanography from the Massachusetts Institute of Technology (MIT) and completed an A.B. in Ecology & Evolutionary Biology at Princeton University, graduating summa cum laude and as a Phi Beta Kappa member, receiving one of six awards for the best senior thesis in the sciences. Sheri holds a PhD in Biological Oceanography from the Massachusetts Institute of Technology (MIT) and completed an A.B. in Ecology & Evolutionary Biology at Princeton University, graduating summa cum laude and as a Phi Beta Kappa member, receiving one of six awards for the best senior thesis in the sciences.

CEO and co-founder

Hervé Affagard

Hervé Affagard is the CEO and co-founder of MaaT Pharma. For the past 15 years, Hervé has been an intra/entrepreneur in the healthcare industry, after starting his career in IT in the steel industry. In late 2014, Hervé co-founded the company alongside Dr. Joël Doré, author of nearly 500 publications, and
one of the world’s most cited authors in the microbiome sphere today, after a professional career that spanned multiple industries. Hervé has led MaaT Pharma’s development from its early concept in 2013 and has been at the forefront of the development of the microbiome healthcare ecosystem in France and Europe. In January 2022, Hervé has been elected President of Allliance Promotion Microbiote, an organization founded in 2021 to support the microbiome sector development in France.

Engineer, MBA