Could a probiotic help stem cell transplant recovery?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative. * Assent, when appropriate, will be obtained per institutional guidelines. * Willingness to be followed for the planned duration of the trial (2 years). * Karnofsky performance status must be \>= 60%. * Any hematologic disorders receiving allogeneic hematopoietic stem cell transplant with reduced intensity conditioning. * Planned 8/8 or 7/8 (human leukocyte antigens \[HLA\]-A, B, C, DR) related or unrelated donor hematopoietic cell transplantation (HCT). * Clinical Laboratory and Organ Function Criteria: Consistent with City of Hope (COH) standard operating procedure (SOP) for "patient evaluation for selection for hematopoietic cell transplantation. * Patient is eligible to receive allogeneic hematopoietic cell transplantation with reduced intensity conditioning. * Agreement by females and males of childbearing potential to use an effective method of birth control or abstain from heterosexual activity for the course of the study through at least 3 months after the last dose of protocol therapy. * Childbearing potential defined as not being surgically sterilized (men and women) or have not been free from menses for \> 1 year (women only). Exclusion Criteria: * Failure of research participant to understand the basic elements of the protocol and/or the risks/benefits of participating in this pilot study. A legal guardian may substitute for the research participant. * Refusing to use contraception up to 90 days post-HCT. * Pregnant and/or breast feeding if a female recipient. * Patients with history of chronic intestinal disease (e.g., Crohn's disease, ulcerative colitis). * In the opinion of the principal investigator (PI), the participant has a condition that will preclude them from complying with study treatment. * Research participants receiving any other investigational agents. * Known or documented history of hypersensitivity to all the listed antibiotics, used for severe infections related to CBM588: * Ampicillin. * Chloramphenicol. * Clindamycin. * Erythromycin. * Metronidazole. * Tetracycline. * Vancomycin. * Research participants with presence of other active malignancy within 2 years of study entry. Participants with history of prior malignancy treated with curative intent who achieved complete response (CR) more than 2 years before study entry are eligible. This exclusion rule does not apply to non-melanoma skin tumors and in-situ cervical cancer. * History of allergic reactions attributed to compounds of similar chemical or biologic composition to study agent (i.e., research participants whom are severe lactose intolerance or intolerance to milk products). * Research participants having any uncontrolled illness including ongoing or active infection. Research participants with known active hepatitis B or C infection; research participants who are human immunodeficiency virus (HIV) seropositive based on testing performed within 4 weeks of enrollment; research participants with any signs or symptoms of active infection, positive blood cultures, or radiological evidence of infections. * Any other condition that would, in the investigator's judgment, contraindicate the patient's participation in the clinical study due to safety concerns with clinical study procedures. * Prospective participants who, in the opinion of the investigator, may not be able to comply with all study procedures (including compliance issues related to feasibility/logistics).