Cancer and immunotherapy: a role for microbiota composition.

Human microbiota plays a key role in preserving homeostasis; therefore, alteration in its composition is associated with susceptibility to various diseases. Recent findings suggest that gut microbiota may influence response to cancer treatment, especially immune checkpoint blockers (ICBs). The development of ICBs has changed outcomes of patients with cancer and has allowed sustained recovery. Unfortunately, some patients do not respond to ICBs, and microbiota may be a promising new biomarker to identify patients who will have benefit from ICBs. This review presents relationship between microbiome composition or microbiota-derived metabolites and response to ICBs or immune-related adverse events. Furthermore, we will present different strategies to modulate microbiota composition in patients to enhance ICB efficacy or dampen their toxicities which could lead to the emergence of interesting complementary treatments.