This clinical trial is focused on patients with hematologic malignancies, which are types of blood cancers. These patients are undergoing a procedure called allogeneic hematopoietic cell transplantation (alloHCT), a treatment that involves replacing diseased bone marrow with healthy cells from a donor. The study is testing a new treatment called MaaT033, which is an oral medication in the form of a prolonged-release capsule. MaaT033 contains a special mixture known as allogeneic fecal microbiota, which is designed to help prevent complications that can occur after the transplantation.

The purpose of the study is to compare the effectiveness of MaaT033 with a placebo in improving overall survival rates at 12 months after the treatment begins. Participants in the study will be randomly assigned to receive either MaaT033 or a placebo, which is a capsule that looks like the treatment but does not contain the active substance. The study is conducted in a way that neither the participants nor the researchers know who is receiving the actual treatment or the placebo, ensuring unbiased results.

Throughout the study, participants will take the medication orally, and their health will be monitored over a period of time to assess the treatment’s impact on their survival and any potential side effects. The study aims to provide valuable information on whether MaaT033 can effectively prevent complications in patients undergoing alloHCT, potentially leading to better outcomes for those with blood cancers.