The human gut is home to trillions of microorganisms, collectively called the microbiota, which affect health and disease. For example, in patients receiving hematopoietic stem cell transplantation as treatment for leukemias, lymphomas and other blood cancers, disruptions in the microbiota have been linked to disease relapse, infections and reduced survival. To address these treatment complications, Drs. David and Sung are developing ways to manipulate the microbiota through prebiotics, carbohydrates that a patient can ingest to stimulate the growth and maintenance of various beneficial bacteria. The challenge is that each patient has different microbiota and therefore may respond differently to the same prebiotic therapy. They are developing approaches for personalizing prebiotic treatments for hematopoietic stem cell transplant (HCT) patients based on their individual gut microbiota. After validating their prebiotic personalization with a mouse model, they will test the safety and feasibility of this treatment in a Phase 1 clinical trial with HCT patients.