MaaT Pharma To Present New Promising Preclinical Data at AACR for MaaT034 Aiming To Improve Patients' Responses to Immunotherapies

Lyon, France, March 31, 2025, 6.00pm CET – MaaT Pharma (EURONEXT: MAAT – the "Company"), a clinical-stage biotechnology company and a leader in the development of Microbiome Ecosystem TherapiesTM (MET) dedicated to enhancing survival for patients with cancer through immune modulation, will present new non clinical data at the American Association for Cancer Research (AACR) Annual Meeting, taking place on April 25-30, 2025 in Chicago, Illinois.

MaaT034 is the Company's next-generation full ecosystem synthetic microbiome therapy and the first candidate from its proprietary MET-C platform. Developed using a co-culturing technology optimized for large-scale production, MaaT034 is designed to improve patient responses to immunotherapy in combination with Immune Checkpoint Inhibitors.

The key findings, obtained from studies conducted in germ-free mice, demonstrate that MaaT034:

Effectively engrafts, thus ensuring an enduring presence of beneficial bacteria in the gut environment.
Potentiates anti-tumor effects mediated by anti-PD-1 checkpoint blockade.
Leads to the production of key microbial-derived metabolites in germ-free mice.
Improves gastrointestinal physiological functions.

In parallel, the Company is developing donor-derived microbiome therapies that are being explored in multiple clinical trials. Among these, MaaT013 has been tested in patients with acute Graft-versus-Host Disease (aGvHD) and advanced melanoma receiving immune checkpoint inhibitors (PICASSO trial).

"While the PICASSO trial builds on MaaT013's established safety and efficacy to potentially unlock significant new market opportunities in oncology, our next-generation candidate, MaaT034 — to be featured at AACR — is designed with an optimized microbiome composition that eliminates the need for donors and incorporates defined and reproducible immunomodulatory properties, offering enhanced therapeutic potential across a broader range of oncology indications," stated Hervé Affagard, CEO and co-founder of MaaT Pharma.

AACR Poster Presentation details:

Title: MaaT034, a new co-cultured microbiome ecosystem therapy candidate, is capable to safely colonize the gastro-intestinal tract of germ-free mice to restore a healthy gut physiology and to stimulate immunity
Abstract Number: 2209
Session Category: Immunology
Session Title: Microbiome, Inflammation, and Cancer
Session Date/ Time: Monday April 28th, 2025 9:00:00 AM U.S Central Time

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About Picasso

PICASSO is a Phase 2a clinical trial sponsored by AP-HP and in collaboration with INRAE and Institut Gustave Roussy, evaluating MaaT013 in combination with immune checkpoint inhibitors, ipilimumab (Yervoy®) and nivolumab (Opdivo®). The trial is fully recruited and have enrolled 70 patients. Key study endpoints include MaaT013 safety profile and best-overall response rate vs placebo as add-on treatment to Ipilimumab + Nivolumab. Clinical Trials.gov: NCT04988841

About MaaT034

MaaT034, currently in preclinical 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-culturing proprietary MET-C platform, MaaT034 is optimized for large-scale production in oncology. Previous presented preclinical data showed that MaaT034 produced key metabolites, recognized as promoting gut barrier restoration and modulating immune responses, such as Short-Chain Fatty Acids (SCFA), secondary bile acids, and tryptophan derivatives. These data support the role of MaaT034 in gut barrier repair and in T cell reactivation either in combination with anti-PD1 or with anti-PD-L1. 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 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.

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," "believe," "expect," "aim", "intend," "may," "anticipate," "estimate," "plan," "project," "will," "can have," "likely," "should," "would," "could" and other words and terms of similar meaning orthe negative thereof. Forward-looking statements are subjectto inherent risks and uncertainties beyond the Company's controlthat 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.

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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