Clinical-stage biotechnology company MaaT Pharma (EURONEXT: MAAT) announced on Monday that it has commenced its Phase 2b trial, named PHOEBUS, assessing MaaT033, a donor-derived microbiome therapy capsule, as an adjunctive treatment for allogeneic hematopoietic stem cell transplant (allo-HSCT) patients with blood cancer.

This international, randomised, double-blind, placebo-controlled study, set to enroll 387 patients across 56 clinical sites, is reportedly the largest of its kind in oncology microbiome therapy.

Regulatory approvals have been secured in France and Germany, with further expansion planned pending additional regulatory clearance.

PHOEBUS aims to evaluate the efficacy of MaaT033 in improving 12-month overall survival rates for allo-HSCT patients. The primary endpoint is overall survival, to be assessed in late 2026. Secondary endpoints include safety and tolerability assessments before and after allo-HSCT, as well as evaluating engraftment of beneficial microbial species from MaaT033.

MaaT033, MaaT Pharma's second drug candidate, is an oral Microbiome Ecosystem TherapyTM designed for ambulatory care. It contains anti-inflammatory ButycoreTM species and targets optimal microbiota function. The drug, granted Orphan Drug Designation by the European Medicines Agency in August 2023, addresses the impact of harsh conditioning treatments on the gut microbiome during allo-HSCT, potentially improving patient survival rates.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is crucial for treating liquid tumours. However, the associated conditioning treatments can harm the gut microbiome, leading to decreased survival, increased graft-vs-host disease risk and infections. In 2021, nearly 20,000 allo-HSCT transplantations were reported in Europe, with continued growth.

MaaT Pharma is dedicated to restoring patient-microbiome symbiosis in oncology. Beyond the PHOEBUS trial, the company has initiated a Phase 3 clinical trial for acute graft-vs-host disease (GvHD). Its gutPrint discovery and analysis platform enables target identification, drug evaluation and biomarker identification for microbiome-related conditions. The company ensures cGMP manufacturing and quality control for its Microbiome Ecosystem Therapies, providing a diverse microbiome in liquid and oral formulations. MaaT Pharma collaborates with world-leading scientists and regulators to integrate microbiome therapies into clinical practice.