Acute graft-versus-host-disease (aGvHD) is a typical complication after allogeneic hematopoetic stem cell transplantation (ASCT). About 30-60% of patients after ASCT are affected by aGvHD, which constitutes a relevant burden of morbidity and mortality in these patients.

Fecal microbiota transplantation (FMT) is a therapeutic concept to treat intestinal dysbiosis of various origin by infusion of the stool microbiota of a healthy donor into the gastrointestinal tract (GI) of a patient. FMT can be performed endoscopically by colonoscopic deployment of the donor microbiota into the patient´s caecum and terminal ileum.

Patients with gastrointestinal aGvHD (GI-aGvHD) are known to comprise a significant dysbiotic colonic microbiota that can be attenuated by FMT.

Inclusion Criteria:

• first episode of histologically confirmed, steroid-refractory GI-aGvHD
• reduced bacterial diversity in the patient´s stool microbiota evidenced by 16s-rDNA measurement
• eligibility for repeated colonoscopic procedures
• informed consent

Exclusion Criteria:

• complications during a previous colonoscopy
• recurrent episode of GI-aGvHD
• lacking cardiopulmonary fitness for repeated colonoscopic procedures
• septic infection
• acute extraintestinal organ failure (excluding bone marrow)
• mechanical ileus