Efficacy and Safety of FMT Capsule Treating Steroid-refractory GI-aGvHD

Inclusion Criteria: 1. Patients must be willing and able to sign the informed consent form and complete the follow-up visits. 2. 18-75 years old. No gender limitation. 3. Patients who can swallow the capsules without chewing. 4. Patients who were clinically diagnosed as steroid refractory GI-aGvHD. The diagnosis criteria are: experiencing GI-aGvHD clinical manifestations (e.g., abdominal cramps, diarrhea, stool blood) within 100 days after receiving hematopoietic stem cell transplant (HSCT); having Grade 2-4 gastrointestinal clinical symptoms; excluding diarrhea caused solely by pathogen infection; after adequate steroid treatment, disease progression on day 3, or with no change on day 7, or without complete response on day 14. 5. Patients who had complicated infection after the diagnosis of aGvHD, but are able to discontinue all the antibiotic therapy 12 hours before receiving FMT treatment. 6. ECOG scale ≤3 7. Basic body function indexes reach the following criteria: total neutrophil≥0.5\*10\^9/L, platelet count≥100\*10\^9/L, serum creatinine ≤1.5×upper limit of normal (ULN) or creatinine clearance≥40 mL/min, albumin≥25g/L. Exclusion Criteria: 1. Patients with extremely serious grade IV aGvHD (life-threatening or with serious non-GvHD complication). 2. Refractory malignant condition. 3. Patients who have received two or more HSCT. 4. Patients who have active infection that has not been controlled and must receive antibiotic therapy, including diarrhea (non-GvHD diarrhea) caused by infection or antibiotics, excluding GvHD complicated infective diarrhea. 5. Patients who have gastrointestinal perforation or toxic intestinal. 6. Patients who have a history of severe allergic reactions. 7. Any condition in which PI do not consider it appropriate to participate (e.g., any medical history, treatment history, or abnormal history of testing data that may confuse the study results, or interfere with the patient's full participation in the study, or hurt the patient's benefit) 8. Female patients who have positive pregnancy test results or are breastfeeding. Women of childbearing age who refuse to use contraception one month after FMT treatment.