LYON, France, April 1, 2026
MaaT Pharma has announced the publication of CHRONOS study data in the peer-reviewed Bone Marrow Transplantation journal, highlighting poor survival outcomes in third-line acute Graft-versus-Host Disease (aGvHD) and reinforcing the urgent need for innovative therapeutic approaches in this high-risk patient population. The study provides real-world clinical evidence from 59 patients with steroid- and ruxolitinib-refractory gastrointestinal aGvHD, demonstrating limited efficacy of current treatment options and supporting the development of microbiome-based immunotherapies such as MaaT013 (Xervyteg®).
CHRONOS Study Highlights Poor Outcomes in Third-Line aGvHD
The CHRONOS study is one of the largest multicenter real-world analyses evaluating outcomes in patients receiving third-line therapies after failure of standard treatments, including corticosteroids and ruxolitinib. Conducted across 16 European transplant centers, the study reflects current clinical practice in managing severe aGvHD cases.
Key findings revealed limited treatment effectiveness and poor survival outcomes, with a Day 28 gastrointestinal overall response rate (GI-ORR) of 37% and a rapid decline in response to 22% by Day 56, indicating a lack of durability in treatment response. Additionally, the 12-month overall survival rate was only 29%, with a median survival of just 86 days, underscoring the critical unmet need for more effective therapies in this setting.
The patient population studied was particularly severe, with over 90% showing resistance to both steroids and ruxolitinib, and nearly all patients presenting with advanced Grade III or IV disease, highlighting the complexity and urgency of treating this condition.
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Microbiome-Based Therapy Shows Potential to Improve Outcomes
The CHRONOS findings provide important context for MaaT Pharma’s investigational therapy MaaT013 (Xervyteg®), a microbiome ecosystem therapy designed to restore immune balance through gut microbiota modulation. The study results were included in the company’s Marketing Authorization Application (MAA) submitted to the European Medicines Agency (EMA), supporting regulatory evaluation of the therapy.
Comparative data from the pivotal ARES trial demonstrated significantly improved outcomes with MaaT013, including a Day 28 GI-ORR of 62% and a 12-month survival rate of 54%, nearly doubling survival compared to CHRONOS results. These findings highlight the potential of microbiome-based therapies to transform treatment paradigms in refractory aGvHD and address critical gaps in current care.
MaaT013 works by restoring the symbiotic relationship between the gut microbiome and the immune system, reducing inflammation and improving immune tolerance, which is essential in managing aGvHD, a condition driven by immune-mediated tissue damage following transplantation.
Regulatory and Clinical Implications for Future Treatment Standards
The publication of CHRONOS data in a leading journal and its presentation at the EBMT 2026 Annual Congress underscores its importance as a benchmark study for regulatory and clinical decision-making. By providing a contemporary reference for third-line treatment outcomes, the study establishes a critical baseline against which new therapies can be evaluated.
Acute GvHD remains a life-threatening complication of bone marrow transplantation, with gastrointestinal involvement leading to severe symptoms such as intestinal bleeding, malnutrition, and increased mortality risk. Current treatment options remain limited, particularly after failure of first- and second-line therapies, making innovation in this field essential.
The CHRONOS study also highlights the lack of standardized treatment approaches and the heterogeneity of third-line therapies, emphasizing the need for evidence-based strategies and regulatory-approved treatments to improve patient outcomes.
A Critical Benchmark for aGvHD Treatment Innovation
The CHRONOS study establishes a real-world clinical benchmark for third-line aGvHD, revealing the limitations of existing therapies and reinforcing the need for novel, effective treatment options. With promising data from microbiome-based therapies like MaaT013, the study supports a potential shift toward innovative immunomodulatory approaches, offering hope for improved survival and quality of life in patients with this devastating condition.
Source: MaaT Pharma press release
