MaaT Pharma has reported a positive outcome from the second safety interim analysis of its Phase 2b Phoebus trial evaluating MaaT033 in patients receiving allogeneic haematopoietic stem cell transplantation (allo-HSCT).

An independent data safety monitoring board (DSMB) completed its review of unblinded safety data from the first 120 enrolled patients, identifying no safety concerns or excess mortality related to MaaT033. Following the analysis, the DSMB recommended that the study continue as planned.

The Phoebus trial, described as the largest randomised controlled trial of a microbiome therapy in oncology to date, is designed to assess the safety and efficacy of MaaT033 compared with placebo in patients undergoing allo-HSCT. These patients face a high risk of complications and mortality in the early post-transplant period, underscoring the need for therapies that can support immune recovery and reduce adverse events.

Hervé Affagard, chief executive officer and co-founder of MaaT Pharma, said: “We are pleased to report another positive safety review for MaaT033 with the DSMB’s recommendation to continue the trial without modification marking a key milestone in its development. We remain fully committed to advancing this Phase 2b trial and to delivering a much-needed therapeutic option for patients fighting blood cancers and undergoing allo-HSCT.”

In line with the study protocol, patients are monitored for 90 days after transplantation, with predefined safety checks and stopping rules in place to ensure patient safety. Regular DSMB reviews are conducted every six months, and all analyses so far have confirmed a favourable safety and tolerability profile for MaaT033.

Patient enrolment is ongoing across France, Germany, Belgium, Spain, the Netherlands and the UK, with a total of 387 participants expected at up to 60 clinical sites. The next DSMB review is scheduled for the first quarter of 2026.

MaaT033 is being developed as an oral microbiome-based therapy intended for use in patients receiving allo-HSCT, with the aim of improving outcomes through immune modulation.