Role of microbiota in the outcome of immune checkpoint inhibition therapy of cancer.

Abstract

The realization that the composition and functionality of gut microbiota have an impact on the outcome of immune checkpoint inhibition (ICI) therapy of cancer has initiated research into the potential of microbiota management as adjunctive therapy. Fecal microbiota transplantation can improve the outcome of ICI, but for optimal donor selection, safety, and large-scale implementation, there remain bottlenecks. Alternative strategies, such as the use of selected bacterial species, require fundamental knowledge of the underlying mechanisms governing the interaction between (intestinal) microbiota and the immune system. Gut microbiota also appears to be able to colonize the tumor microenvironment. Some bacterial species directly or indirectly promote tumor growth. Other defined species have tumoricidal properties. These findings and insights are now being used to further optimize the functionality of the immune system and shape the tumor microenvironment in order to improve the outcome of ICI.