Impact of Gut Microbiome on Immune Response to Cancer Immunotherapy

Researchers at MD Anderson Cancer Center have discovered that specific gut bacteria can dramatically influence how well patients respond to immune checkpoint inhibitor therapies, a groundbreaking form of cancer treatment that helps the immune system recognize and attack cancer cells. In a study involving 438 melanoma patients receiving checkpoint inhibitor therapy, those with high levels of certain bacterial species, particularly Akkermansia muciniphila and several Ruminococcaceae species, had response rates nearly double those of patients lacking these bacteria. The researchers also found that patients who had received antibiotics in the months before treatment had significantly reduced response rates and shorter survival times. In follow-up experiments, the team found they could transfer the benefit by transplanting fecal material from responding patients into germ-free mice. Mice receiving microbiome transplants from human responders showed tumor reduction when treated with checkpoint inhibitors, while those receiving transplants from non-responders showed little benefit from the therapy. This discovery has already led to clinical trials of microbiome modification strategies, including fecal transplantation, probiotic supplementation, and specialized diets designed to encourage beneficial bacteria growth. Initial results suggest that these interventions could potentially increase the number of patients who benefit from immunotherapy treatments.