Probiotics for the Prevention of Immunotherapy Induced Colitis in Patients Receiving Immunotherapy

Inclusion Criteria: * Male or female age ≥ 18 years * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 * Histologically confirmed solid malignancy * Will be starting on ICIs or have started ≤ 2 cycles of ICIs * For cohort 1: Ipilimumab with or without anti-PD-1/PD-L1 including but not limited to pembrolizumab, nivolumab, cemiplimab, atezolizumab, avelumab, or durvalumab * For cohort 2: Anti-PD-1/PD-L1 described above with or without chemotherapy * Absolute neutrophil count (ANC) ≥ 1000/mm\^3 * Platelet count ≥ 75,000/mm\^3 * Hemoglobin ≥ 9.0 g/dL * Creatinine ≤ 2 x upper limit of normal (ULN) * Serum glutamic-oxaloacetic transaminase (SGOT) \[aspartate transaminase (AST)\] ≤ 2 x ULN * Albumin ≥ 3 g/dL * Willing and able to provide research stool and blood samples * Negative serum pregnancy test done ≤ 7 days prior to enrollment, for women of childbearing potential only * Capable of providing valid informed consent * Willing to return to enrolling institution for all study visits (blood draws, etc) Exclusion Criteria: * Requires prolonged systemic antibiotic therapy for other condition and recent systemic antibiotic within the past 2 weeks * Fecal microbiota transplant (FMT) within the past 6 months * FMT with an associated serious adverse event related to the FMT product or procedure * Co-morbid systemic illnesses or other severe concurrent disease which, in the judgment of the investigator, would make the patient inappropriate for entry into this stud…