Stool Transplant to Control Treatment-related Diarrhea

Inclusion Criteria: * ≥ 18 years old * Patient has been treated with immune checkpoint inhibitors (ICI), including anti-CTLA-4, anti-PD-1 and anti-PDL-1 therapy for any malignant indication * Patient has developed diarrhea ≥ Grade 2 attributed to ICI * Patient has diarrhea ≥ Grade 2 attributed to ICI, that persists despite treatment with corticosteroids for at least 72 hours and/or at least one dose of a biologic medication, such as infliximab or vedolizumab, with symptoms that persist or recur at least 72 hours post-infusion ° If no to the above, patient has a contraindictation to immunosuppressive treatment Exclusion Criteria: * Active GI infection, including untreated viral, bacterial or fungal or alternative identified cause(s) of diarrhea. * Antibiotic exposure within 48 hours prior to FMT * Expected prolonged compromised immunity indicated by at least one of the below: * Known HIV infection with CD4 count \<240 * ANC \<1000/mm3 (use of growth factors to raise ANC is acceptable) * Seronegative for EBV or CMV (i.e. EBV IgG negative or CMV IgG negative) * Contraindications to anesthesia for procedure indicated by at least one of the below: * Serious cardiopulmonary comorbidities * Inability to tolerate anesthesia * Pregnancy * Patient is pregnant * Women of childbearing potential should not have plans to became pregnant or breastfeed an infant and must agree to use a highly effective method of birth control until 2 months after treatment with FMT (e.g. barrier method, oral or parenteral contraceptives, a vasectomized partner, or abstinence from sexual intercourse) * Severe food allergies