Fecal Microbiota Transplantation After HSCT

Inclusion Criteria: * Men or women ≥ 18 and ≤ 65 years old * Patients designated to undergo myeloablative or intermediate intensity allogeneic peripheral blood or bone marrow hematopoietic cell transplantation. Consent will be obtained prior to admission for HSCT. Patients receiving any donor source of stem cells are eligible. Eligible conditioning regimens are those defined as myeloablative by Consensus Criteria (Bacigalupo 2009) as well as the combination of fludarabine with melphalan (100-140 mg/mg2) * Any Graft-vs-Host disease (GVHD) prophylaxis regimen is allowed. * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 (Karnofsky ≥ 60%, see Appendix A) * Patients with adequate physical function as measured by * Cardiac: Left ventricular ejection fraction at rest must be ≥ 40%, or shortening fraction \>25%. * Hepatic: * Bilirubin ≤ 2.5 mg/dL, except for patients with Gilbert's syndrome or hemolysis * Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and Alkaline Phosphatase \< 5 x Upper Limit of Institutional Normal Range (ULN). * Renal: Serum creatinine within normal range, or if serum creatinine is outside normal range, then renal function (measured or estimated creatinine clearance or GFR) ≥ 40millileters/min/1.73m2. * Pulmonary: Diffusing lung capacity for carbon monoxide (DLCO) (corrected for hemoglobin), Forced expiratory volume in 1 second (FEV1) and Forced vital capacity (FVC) ≥ 50% predicted. * Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study and for 3 months after FMT. * Ability to understand and the willingness to sign a written informed consent document, including the willingness to accept risk of unrelated donor stool. * Ability to swallow oral medications. Exclusion Criteria: * Prior allogeneic hematopoietic stem cell transplantation. (Patients may have received a prior autologous hematopoietic stem cell transplant.) * Participants who are receiving any other investigational agents. * Uncontrolled intercurrent illness including, but not limited to, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Patients with active or uncontrolled bacterial, viral, or fungal infection(s) requiring systemic therapy. * Patients with history of primary idiopathic myelofibrosis or any severe marrow fibrosis. * Planned use of prophylactic donor lymphocyte infusion (DLI) therapy. * Delayed gastric emptying syndrome * Known chronic aspiration * Patients with a history of significant allergy to foods not excluded from the donor diet (excluded foods are tree nuts, peanuts, shellfish, eggs) * Pregnant and breast-feeding women are ineligible because they are not eligible for hematopoietic stem cell transplantation. * HIV-positive participants are ineligible. * Participants who are unable to swallow pills. * Participants with end-stage liver disease (cirrhosis) * Participants with acute, active gastrointestinal infection (e.g., typhlitis, diverticulitis, appendicitis) * Participants with inflammatory bowel disease (e.g., ulcerative colitis, Crohn's)