Uncovering the role of the gut microbiota in immune checkpoint blockade therapy: A mini-review

In recent years, the microbiota has been implicated as a key factor associated with both response and toxicity from immune checkpoint blockade therapy. Numerous studies have been published that specifically highlight the importance of the microbiome as a distinct influencer of anti-PD-1/PD-L1 and anti-CTLA-4 activity in cancer patients, but a full understanding of mechanisms behind these interactions has yet to be achieved. With greater insight into how the microbiome can modulate immune checkpoint blockade comes the potential to target the microbiome to improve response rates and minimize toxicities. This mini-review looks at noteworthy studies that have explored the relationship between the microbiome and immune checkpoint blockade response and toxicity in both preclinical and clinical studies, with an emphasis on current hypotheses regarding mechanisms of action and potential microbiome-targeted therapeutic strategies under development.