MaaT Pharma to Seek EMA Re-Examination After CHMP Issues Negative Opinion on Conditional Marketing Application for Xervyteg® in Acute Graft-versus-Host Disease
Clinical-stage biotechnology company MaaT Pharma has announced that the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) has formally adopted a negative opinion on the company’s conditional Marketing Authorization Application (MAA) for MaaT013, proposed under the brand name Xervyteg®, for the treatment of adults with acute Graft-versus-Host Disease (aGvHD) involving the gastrointestinal tract who have failed previous lines of therapy.
The decision confirms the negative trend opinion that the company had previously disclosed in May 2026. While the outcome represents a significant regulatory setback, MaaT Pharma has reaffirmed its commitment to pursuing approval through the EMA’s re-examination process and remains confident in the therapeutic potential of MaaT013 based on clinical trial findings and extensive real-world patient experience.
The company believes that patients suffering from severe gastrointestinal aGvHD continue to face a substantial unmet medical need, particularly after failure of existing therapies, and intends to present additional scientific arguments supporting the benefit-risk profile of the investigational microbiome therapy.
CHMP Confirms Earlier Regulatory Concerns
The formal opinion adopted by the CHMP on June 25, 2026, aligns with the committee’s previously communicated concerns regarding the evidence supporting MaaT013’s conditional approval.
According to the committee, the available clinical data do not sufficiently demonstrate that the observed treatment benefits and safety outcomes can be attributed solely to MaaT013 because patients enrolled in the clinical studies also received multiple concomitant therapies commonly used to manage acute Graft-versus-Host Disease.
The CHMP’s assessment focused primarily on results from the ARES study, a single-arm clinical trial that evaluated MaaT013 in patients with severe gastrointestinal aGvHD who had become refractory to previous treatments.
While acknowledging the clinical outcomes observed in the study, the committee maintained that the absence of a randomized control group makes it difficult to isolate the specific contribution of MaaT013 from other therapies administered simultaneously during patient management.
As a result, the committee concluded that the current evidence package does not yet satisfy the requirements necessary to support conditional marketing authorization.
Company Will Pursue Formal Re-Examination
Despite the unfavorable opinion, MaaT Pharma emphasized that the European regulatory process provides an opportunity for applicants to request a formal re-examination of CHMP decisions.
The company confirmed that it will proceed with this process, consistent with plans announced following the earlier negative trend opinion.
Under EMA procedures, the re-examination involves appointing a new rapporteur and co-rapporteur, who will independently reassess the complete marketing authorization dossier without being involved in the original evaluation.
This independent review is intended to provide a fresh scientific assessment of the evidence submitted in support of the application.
MaaT Pharma believes that the re-examination will offer an opportunity to further clarify the clinical data and address the questions raised during the initial review.
Scientific Advisory Group to Provide Additional Clinical Perspective
As part of the re-examination process, MaaT Pharma also plans to request the convening of a Scientific Advisory Group (SAG) composed of independent hematology experts with experience treating acute Graft-versus-Host Disease.
The company expects that these specialists will provide additional context regarding the complexities of managing patients with severe aGvHD, particularly those who require multiple concomitant therapies because of the aggressive and life-threatening nature of the disease.
According to MaaT Pharma, current clinical practice often necessitates combination treatment strategies, making it difficult to evaluate any single intervention in complete isolation.
The company hopes that expert input will help the CHMP better appreciate the realities of treating patients whose disease has progressed despite multiple prior therapies and for whom few effective treatment options currently exist.
The hearing is also expected to highlight the substantial unmet medical need faced by this patient population and the importance of expanding therapeutic choices.
Regulatory Timeline for a New Decision
Based on standard EMA procedures, MaaT Pharma expects the re-examination process to move relatively quickly.
Once the EMA validates the company’s request, the new scientific evaluation is anticipated to take approximately 60 days.
If the review proceeds according to current timelines, the company expects a second CHMP opinion to be issued during the committee’s September 14–17, 2026 meeting.
The outcome of that review will determine whether the committee modifies its original position or maintains the previously adopted negative opinion.
Confidence in MaaT013 Remains Unchanged
Although acknowledging the regulatory challenges, MaaT Pharma reiterated its confidence in MaaT013’s clinical profile and therapeutic potential.
The company maintains that the investigational microbiome therapy has demonstrated encouraging efficacy and safety in patients with severe gastrointestinal acute Graft-versus-Host Disease who have exhausted available treatment options.
Acute Graft-versus-Host Disease remains one of the most serious complications following allogeneic hematopoietic stem cell transplantation.
The disease occurs when donor immune cells attack the recipient’s tissues, frequently affecting the skin, liver, and gastrointestinal tract.
Patients who develop steroid-refractory or treatment-refractory gastrointestinal involvement generally face poor clinical outcomes, with limited therapeutic alternatives available after failure of second-line treatment.
MaaT Pharma believes MaaT013 has the potential to address this significant unmet need by restoring microbiome balance and modulating immune responses through its proprietary Microbiome Ecosystem Therapy™ platform.
Clinical Evidence Supporting the Program
The company’s confidence is supported by multiple sources of clinical evidence.
The primary data package submitted to European regulators includes findings from the ARES clinical study, which evaluated MaaT013 in patients with severe gastrointestinal aGvHD.
In addition, MaaT Pharma points to supportive evidence generated through the CHRONOS study, published by Clausen and colleagues in 2026.
The company believes that together these studies provide meaningful evidence supporting the therapy’s potential clinical benefit in a patient population with otherwise limited treatment options.
Beyond formal clinical trials, MaaT Pharma has also accumulated substantial real-world experience through its Early Access Program.
Early Access Program Continues Across Europe
One of the company’s strongest sources of supporting evidence comes from its ongoing Early Access Program, which has been operating since 2019.
The program currently spans 13 countries and has provided MaaT013 treatment to more than 300 patients suffering from severe acute Graft-versus-Host Disease.
According to MaaT Pharma, the accumulated experience from routine clinical practice complements the findings observed in controlled clinical studies and further supports the therapy’s benefit-risk profile.
Importantly, the company confirmed that the current regulatory review does not affect the continuation of the Early Access Program.
Eligible patients will continue to receive MaaT013 through existing access mechanisms while the EMA re-examination process proceeds.
This continuity ensures that patients with few remaining treatment options will continue to have access to the investigational therapy where permitted.
Building a Broader Microbiome Therapeutics Pipeline
While MaaT013 remains the company’s most advanced clinical program, MaaT Pharma emphasized that its long-term strategy extends well beyond a single product.
The company continues to advance multiple microbiome-based therapies designed to improve outcomes for patients with hematological malignancies and other immune-related conditions.
Among these is MaaT033, an oral microbiome therapy currently being evaluated in a randomized Phase 2 clinical trial.
Unlike MaaT013, which is intended for treatment of established disease, MaaT033 is being investigated primarily as a prophylactic therapy for patients undergoing hematological cancer treatment.
The oral formulation is designed for broader outpatient use and aims to help prevent complications associated with immune dysfunction following stem cell transplantation.
If successful, MaaT033 could expand the application of microbiome therapeutics into earlier stages of patient care.
Expanding into Immuno-Oncology
MaaT Pharma is also investing in the next generation of its microbiome platform through development of MaaT034, a product candidate intended for immuno-oncology applications.
The investigational therapy reflects the company’s broader vision of using microbiome modulation to enhance immune responses against cancer while improving treatment outcomes.
Growing scientific evidence continues to suggest that the gut microbiome plays an important role in regulating immune function and may influence responses to immunotherapies across multiple cancer types.
By leveraging its proprietary Microbiome Ecosystem Therapies™ platform, MaaT Pharma aims to develop treatments capable of modifying immune activity in ways that benefit patients with serious hematological diseases and cancer.
Although the CHMP’s negative opinion represents an important regulatory obstacle, MaaT Pharma remains committed to pursuing European approval for MaaT013 through the formal re-examination process. The company believes that additional scientific review, expert clinical input, and a fresh assessment of the evidence will provide an opportunity to further demonstrate the therapy’s value for patients with severe gastrointestinal acute Graft-versus-Host Disease who have exhausted existing treatment options.
At the same time, MaaT Pharma continues to advance a broader portfolio of microbiome-based therapies, supported by ongoing clinical development, real-world treatment experience, and expanding research into immune modulation. As the company prepares for the next stage of regulatory review, it remains focused on its overarching mission of improving survival and quality of life for patients with cancer and other life-threatening immune-mediated conditions through innovative microbiome therapeutics.
About MaaT Pharma
MaaT Pharma is a leading, late-stage clinical company focused on developing innovative gut microbiome-driven therapies to modulate the immune system and enhance cancer patient survival. Supported by a talented team committed to making a difference for patients worldwide, the Company was founded in 2014 and is based in Lyon, France. As a pioneer, MaaT Pharma is leading the way in bringing the first microbiome-driven immunomodulator in oncology.
Using its proprietary pooling and co-cultivation technologies, MaaT Pharma develops high diversity, standardized drug candidates, aiming at extending life of cancer patients. MaaT Pharma has been listed on Euronext Paris (ticker: MAAT) since 2021.
About acute Graft-versus-Host Disease
Acute Graft-versus-Host Disease 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, causing inflammation of the skin, liver and/or gastrointestinal tract and leading to significant morbidity and mortality. GI involvement is associated with severe complications such as profound diarrhea, abdominal pain, intestinal bleeding, and death. These complications are often life-threatening, with increased mortality risk, due to the challenges of managing severe GI inflammation and the associated risks of infection, malnutrition, and organ failure.
The standard first-line therapy for treating aGvHD is the use of systemic steroids. If patients do not respond to steroids, they are considered steroid resistant (SR) and other agents can be administered. Currently, ruxolitinib is the standard second-line treatment for steroid-refractory acute graft-versus-host disease. More recently, remestemcel‑L (rknd) was approved in December 2024 in the United States, specifically for use in the pediatric population as a second-line treatment.
About MaaT013 (Xervyteg®)
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. MaaT013 (Xervyteg®) is a full-ecosystem, off-the-shelf, standardized, pooled-donors, enema Microbiome Ecosystem TherapyTM for acute, hospital use. It is characterized by a consistently high diversity and richness of microbial species and the presence of ButycoreTM (a group of bacterial species known to produce anti-inflammatory metabolites).
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 the symptoms of 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).
