Modulation of cancer immunotherapy efficacy by gut microbiota.

The microbial community is present abundantly in mucosal organs including the intestine, the oral cavity, and the vagina, and is referred to as the microbiota. The microbiota is composed of commensal bacteria and other microorganisms. Intestinal colonization by commensal microorganisms is essential for host physiological functions from the maintenance of barrier homeostasis locally to the regulation of metabolism, hematopoiesis, inflammation, immune development, and other functions systemically. Evidence is growing that the gut microbiota can modulate the host response to cancer immunotherapy. In this review, we discuss the evidence for the ability of the microbiota to modulate immunotherapy, their mechanisms of action, and the possibility of altering the microbiota to improve immunotherapy efficacy.