Primary Objective:

1. To evaluate the safety of orally administered Lactobacillus plantarum strains 299 and 299v, a probiotic, in patients undergoing allogeneic myeloablative HSCT, as measured by incidence of Lactobacillus plantarum bacteremia.

Secondary Objectives:

1. To investigate the feasibility of administering Lactobacillus plantarum 299 and 299v to children and adolescents undergoing HSCT.
2. To describe the overall incidence of bacteremia in HSCT patients who have been administered Lactobacillus plantarum.
3. To describe the overall incidence of acute graft versus host disease (GVHD) in HSCT patients who have been administered Lactobacillus plantarum.

Myeloablative regimens are the backbone of hematopoietic stem cell transplantation (HSCT) and are associated with prolonged periods of cachexia/anorexia, nausea/vomiting, mucositis, and compromised gut integrity (CGI). The toxicities associated with HSCT often lead to prolonged periods of poor oral intake and may result in overt malnutrition. CGI decreases oral tolerance to foods, reduces Quality of Life (QOL) and functional status, delays the transition from the hospital to home setting, and increases the risk of the development of gut-derived infections. Probiotics are nutritional supplements that contain a defined amount of viable microorganisms and upon administration confer a benefit to the host. Clinical trials in adults receiving organ transplants have found probiotics decrease the incidence of infection, the duration of antibiotic use, the incidence of multiorgan failure and systemic inflammation. Children and adolescents undergoing HSCT, experience similar clinical challenges suggesting probiotics may have a therapeutic value in the setting of HSCT. This study is to evaluate the safety and feasibility of administering probiotics to children and adolescents undergoing HSCT.

Inclusion Criteria:

• All patients undergoing myeloablative allogeneic HSCT will be eligible. The source of stem cells can be from bone marrow, umbilical cord blood or cytokine mobilized peripheral blood. Donor can be human leukocyte antigen (HLA) matched sibling or parent, a related donor mismatched for a single HLA locus (class I or II), unrelated marrow or peripheral blood stem cell donor, or unrelated cord blood at least 4/6 antigen match (Class 1 or II).
• Patients of either gender and between 2 and 17.99 years of age
• Patients receiving any type of GVHD prophylaxis are eligible.

Exclusion Criteria:

• Patients who have self-prescribed probiotics within 3 months of starting the conditioning regimen for stem cell transplant (consumption of yogurt products is allowed).
• Patients with known allergy to oats.
• Patients who have had any type of gut damage within the past three months; such as, previous bowel perforations; previous episode of Grade 4 neutropenic colitis or typhlitis.
• Patients with inflammatory bowel syndrome, short small bowel syndrome, Crohns Disease, Ulcerative Colitis, and patients with a history of bowel resections.
• Patients who have undergone a previous allogeneic HSCT.

Adverse event data were collected and reported up to Day +100