Erik Orberg, MD, PhD, University Hospital of the Technical University of Munich, Munich, Germany, discusses the link between the microbiome and graft-versus-host disease (GvHD) in patients undergoing allogeneic stem cell transplantation. The metabolic profile of patients were analyzed and the presence of indole and desaminotyrosine indicated a lower risk of GvHD. The presence of metabolites can additionally stimulate epithelial growth, suggesting the use of metabolites as a prophylactic treatment in patients undergoing transplant. This interview took place at the 63rd ASH Annual Meeting and Exposition congress in Atlanta, GA.