MaaT Pharma Presents Preclinical Data at AACR Annual Meeting Demonstrating Immune Activation and Anti-Tumor Activity of MaaT034

Lyon, France, April 28, 2025, 6.00pm CET - MaaT Pharma (EURONEXT: MAAT - the "Company"), a clinical-stage biotechnology company and a leader in the development of Microbiome Ecosystem Therapies™ (MET) dedicated to enhancing survival for patients with cancer through immune modulation, today presented new preclinical data for MaaT034, the Company's next generation product, showing compelling anti-tumor efficacy results in germ-free mice at the American Association for Cancer Research (AACR) Annual Meeting 2025 in Chicago, Illinois, taking place from April 25 to 30, 2025.

MaaT Pharma has built a versatile platform combining two complementary approaches. The first one leverages a GMP-compliant approach to produce standardized donor-derived therapies (MaaT013, MaaT033) using pooled donations, proven to restore a rich and diverse gut microbiome for patients with severe dysbiosis and currently in late-stage of clinical evaluation (Phases 2 and 3). In parallel, the Company is advancing a next-generation, Al-driven co-culture technology to develop a donor-independent synthetic microbiomeecosystem at large industrial scale targeting indication-specific diseases. MaaT034, the first-in-class co-cultured product, aims to optimize intestinal microbiome functions and to improve patient responses to immunotherapy in combination with Immune Checkpoint Inhibitors.

Below are the key results presented at AACR for MaaT034:

· Metagenomic analysis shows that MaaT034 reproduces the microbial functions of MaaT013 - the Company's lead asset, currently evaluated in the randomized Phase 2 PICASSO trial in combination with immune checkpoint inhibitors (ICI), ipilimumab (Yervoy®) and nivolumab (Opdivo®) for unresectable or metastatic melanoma.
· · MaaT034 improves DC-mediated T cell activation and potentiates anti-tumor effects mediated by anti-PD-1 checkpoint blockade in vitro.
· 70% of MaaT034 microbial species engraft in mice, ensuring an enduring presence of beneficial bacteria in the gut environment.
· MaaT034 increases the production of key microbial-derived metabolites such as shortchain fatty acids in germ-free mice. This translates into an improved gastrointestinal physiology as evidenced by gut mucosal restoration.

· MaaT034 optimizes anti-PD1 mediated activity in tumor-bearing, germ-free mice. While anti-PD1 alone reduced tumor growth by 10%, the combination of anti-PD1 and MaaT034 resulted in a 83.7% tumor growth reduction (compared to a 24.2% reduction when using a single strain of Akkermansia muciniphila' bacteria). These results demonstrate that improved tumor control is achieved with anti-PD1 in combination with MaaT034, as compared to PD-1 alone or in combination with a reference single bacterial strain.

"These positive data in tumor-bearing mice demonstrate the significant potential of MaaT034 as a microbiome ecosystem therapy candidate and provide a robust basis for the progression of this therapy into clinical development for solid tumors. We look forward to further evaluating the potential benefits of MaaT034 in the next phases of our research," said Gianfranco Pittari, MD PhD, Chief Medical Officer, MaaT Pharma.

Upcoming conferences participation

· May 5-6, 2025 Swiss Biotech Day, Basel
· May 13, 2025 Forum Midcaps Gilbert Dupont, Paris
· June 12-15 European Hematology Association (EHA) Congress, Milan, IT
· June 16-19, 2025 Bio International Convention, Boston, MA Company Presentation
· June 18-19, 2025 Portzamparc Conference Mid & Small Caps 2025, Paris
· September 25, 2025 KBC Healthcare Conference, Brussels

About MaaT034

MaaT034, currently in precinical development, is a next-generation donor-independent full ecosystem synthetic microbiome therapy, dedicated to improving patient responses to immunotherapy in combination with Immune Checkpoint Inhibitors. Developed using the Company's co-oulturing proprietary MET-C platform, MaaT034 is optimized for large-scale production in oncology. Previous presented precimical data showed that MaaT034 produced key metablites, recognized as promoting gut barrier restoration and modulating immune responses, such as Short-Chain Fatty Acids, and tryptophan derivatives. These data support the role of MaaT034 in gut barrier repair and in T cell reactivation with anti-PDT or with anti-PD-1. By enhancing gut barrier repair and modulating immune responses, MaaT034 is expected to complement the action of these immunotherapeutic agents, potentially improving their efficacy in treating solid tumors cancer.

About MaaT Pharma

MaaT Pharma is a leading, late-stage clinical company focused on developing innovative 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.

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 and (ii) factors beyond the Company's control. These statements may include, without limitation, any statements preceded by, followed by, or including words such as "target," "aim", "intend," "may," "enticipate," "estimate," "plan," "project," will," "canhave," "likely," "would," "could" and other words and terms of similar meaning or the negative thereof. Forward-lookingstatement sare subject on hertainties beyond the Company's control that could cause the Company's actual results or performance to be materially different from the expected results or performance expressed or implied by such forward-looking statements.

¹ Akkermansia muciniphila is a commensal bacterium naturally present in large quantities in the gut microbiota of healthy people.

Contacts

MaaT Pharma – Investor Relations

Guilhaume DEBROAS, Ph.D. Head of Investor Relations +33 6 16 48 92 50 [email protected]

Rx Communications Group -

U.S. Investor Relations Michael Miller Managing Director +1-917-633-6086 [email protected]

MaaT Pharma – Media Relations

Pauline RICHAUD Senior PR & Corporate Communications Manager +33 6 14 06 45 92 [email protected]

Catalytic Agency -

U.S. Media Relations Heather Shea Media relations for MaaT Pharma +1 617-286-2013 [email protected]

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