Microbial Allies: How Gut Microbiota Influence the Effectiveness of Immune Checkpoint Inhibitors

Abstract

The importance of the gut microbiota in human health and disease has been known for a long time. Current investigations involving preclinical and clinical studies have presented numerous lines of evidence indicating that gut microbiota can influence the effectiveness of cancer immunotherapies, particularly immune checkpoint inhibitors (ICIs). The gut microbiota can alter the immune response in the tumor microenvironment (TME) by engaging with innate and adaptive immune cells. Notably, one of the primary methods by which the gut microbiota modulates antitumor immunity is through the production of metabolites, which are small molecules capable of traveling from the gut to other parts of the body and influencing local and systemic antitumor immune responses. This exploration of mechanisms has yielded valuable insights for developing microbiota-based therapeutic strategies such as fecal microbiota transplantation (FMT), probiotics, engineered microbiomes, and specific microbial metabolites. In this review, we explored several possible interventions that could enhance the efficacy of ICIs, thereby potentially restoring or augmenting patient responses to these therapeutic agents.