Faecal Microbiota Transplantation After Allogeneic Stem Cell Transplantation

Inclusion Criteria: * Patient aged 18 or over * Men and women * Patients affiliated with a social-security organization * Patients undergoing a myelo-ablative allo-HSCT for a controlled haematologic malignant disease, with peripheral stem cells, whatever the type of donor (except cord blood) * Signed and dated informed consent Exclusion Criteria: * Status of tumor progression at the time of allo-HSCT * Inability to understand the protocol (linguistic barrier, cognitive difficulties) * Medical history of another progressive cancer or occurrence in the 3 previous years (excluding basal cell carcinoma) * Presence of a simultaneous serious and uncontrolled disease (severe cardiac, renal, hepatic or respiratory failure, severe sepsis) * Fecal incontinence * Participation in another clinical trial studying an allograft procedure including the type of graft, the type of immunosuppression, a preventive or a curative treatment of GvHD, or studying the effectiveness of a FMT in another indication. * Pregnant women * Patient under guardianship, curatorship or protection of justice