Fecal Microbiota Transplant for Hematologic and Oncologic Diseases: Principle and Practice

Understanding of the importance of the normal intestinal microbial community in regulating microbial homeostasis, host metabolism, adaptive immune responses, and gut barrier functions has opened up the possibility of manipulating the microbial composition to modulate the activity of various intestinal and systemic diseases using fecal microbiota transplant (FMT). It is therefore not surprising that use of FMT, especially for treating relapsed/refractory Clostridioides difficile infections (CDI), has increased over the last decade. Due to the complexity associated with and treatment for these diseases, patients with hematologic and oncologic diseases are particularly susceptible to complications related to altered intestinal microbial composition. Therefore, they are an ideal population for exploring FMT as a therapeutic approach. However, there are inherent factors presenting as obstacles for the use of FMT in these patients. In this review paper, we discussed the principles and biologic effects of FMT, examined the factors rendering patients with hematologic and oncologic conditions to increased risks for relapsed/refractory CDI, explored ongoing FMT studies, and proposed novel uses for FMT in these groups of patients. Finally, we also addressed the challenges of applying FMT to these groups of patients and proposed ways to overcome these challenges.