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Press release

MaaT Pharma Receives Negative CHMP Trend Vote for MaaT013 (Xervyteg ®) Following Re -Examination for its Conditional Marketing Authorization Application in Europe

• MaaT Pharma was informed of a negative trend during the Committee for Medicinal Products for Human Use (CHMP) ’s Oral Explanation meet ing which took place on September 14, 2026
• Formal CHMP opinion is expected on September 1 8, 2026
• Based on the feedback received following the Oral Explanation, t he remaining concerns relate primarily to the attribution of clinical benefit and safety in the absence o f a Random ized Con trol T rial
• The Company will provide further updates following the formal CHMP opinion

Lyon, France, September, 15, 2026 – 7:30am CET - MaaT Pharma (EURONEXT: MAAT – the “Company”), a clinical -stage biotechnology company and a leader in the development of Microbiome Ecosystem Therapies TM (MET) dedicated to enhancing survival for patients with cancer through immune modulation, today announced that it has been informed by the CHMP of the European Medicines Agency (EMA) of a “negative trend ” opinion following the Oral Explanation , as part of the re-examination proce dure of its conditional Marketing Authorization Application (MAA) for MaaT013 (Xervyteg ®) for the treatment of aGvHD, following yeste rda y’s CHMP oral explanation.

"We are deeply disappointed by this outcome . Patients suffering from gastrointestinal -aGvHD continue to face a life -threatening condition with significant unmet medical need and limited treatment options," said Hervé Affagard, Chief Executive Officer and co -founder of MaaT Pharma. " Together with the hematology community, w e remain committed to these patients and will evaluate all available options to make this potentially important treatment accessible to patients worldwide."

Based on the feedback received post Oral Explan ation , the C HMP maintained its view that the available clinical data package, primarily in the absence of a randomized control trial , does not allow sufficient characterization of the benefit/risk of MaaT013 (Xervyteg ®).

Th e C omp any wi ll provid e add itional det ails following the form al C HMP o pinion , which is expected to be communicated on September 1 8, 2026. The Company will assess the implications of the decision and evaluate all available options and will provide an update to the market as appropriate.

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 pati ents 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 the only agent approved for treating SR aGvHD after failure of steroid treatment is ru xolitinib, which is currently approved for this indication in USA and has received approval from the European Medicines Agency’s Committee for Human Medicinal Products (CHMP) on March 25, 2022.

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 Therapy TM for acute, hospital use. It is characterized by a consistently high diversity and richness of microbial species and the presence of Butycore TM (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 steroid -resistant, gastrointestinal (GI) -aGvHD. Xe rvyteg ® (MaaT013) has been granted Orphan Drug Designation by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).

Forward -looking Statements

All statements other than statements of historical fact included in this press release about future events are subject to (i) change without notice