Lactobacillus Rhamnosus GG in Reducing Incidence of Graft-Versus-Host Disease in Patients Who Have Undergone Donor Stem Cell Transplant

PRIMARY OBJECTIVES: I. To determine if hematopoietic stem cell transplant (HSCT) patients treated with a probiotic (Lactobacillus GG \[Lactobacillus rhamnosus GG\])-containing diet compared to those not assigned to receive probiotic have a lower incidence of grade 1 upper gastrointestinal (GI) or grade 2-4 lower GI acute graft-versus-host disease (GVHD) (aGVHD) using Center for International Blood and Marrow Transplant Research (CIBMTR) scoring than those not prescribed a probiotic. II. To determine if HSCT patients treated with a probiotic-containing diet compared to those not assigned to receive a probiotic have a: a) lower rate of organ-specific acute aGVHD (intestinal tract, skin, liver); b) lower rate of moderate or severe chronic GVHD (National Institutes of Health \[NIH\] consensus scoring) at 6 months and 1 year post transplant; c) shorter duration of immunosuppressive therapy (normalized for age and degree of human leukocyte antigen \[HLA\] match); d) lower rate of bacterial and/or opportunistic infection. SECONDARY OBJECTIVES: I. To determine if allogeneic hematopoietic stem cell patients treated with a probiotic compared to those not assigned to receive a probiotic have differences in: a) composition and proportion of the major gut bacterial phylotypes in stool (to be analyzed for changes pre- and post-initiation of probiotics and for association with development of aGVHD); b) measures of inflammation as assessed by cytokine or receptor production (interleukin \[IL\]-6, IL-8, tumor necrosis factor \[TNF\]-alpha, TNF-receptor 1, interferon-gamma, IL-2R, IL-10); c) qualitative measures of immune reconstitution as determined by sequential measurements of conventional T cells, regulatory T regulatory, B cells and natural killer (NK) cells; d) antibody class/subclass production; e) biomarkers associated with GVHD-elafin, regenerating islet-derived 3 alpha (Reg3a), suppressor of tumorigenicity-2 (ST2), hepatocyte growth factor (HGF); and/or urinary tryptophan metabolites; f) markers of gut barrier function including blood levels of endotoxin and microbial deoxyribonucleic acid (DNA). OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive Lactobacillus rhamnosus GG orally (PO) once daily (QD) for 1 year. ARM II: Patients receive no intervention.