A new type of immunotherapy that enables T-cells to fight cancer cells is proving hopeful for people with the deadly skin cancer melanoma, and a new study has found that a high-fiber diet improves the effectiveness of the therapy. Researchers from the University of Texas MD Anderson Cancer Center reported in Science that, by analyzing the gut microbiome in hundreds of patients, they found that higher dietary fiber intake was linked with disease non-progression among patients receiving immune checkpoint blockade therapy compared to patients eating little fiber. The results were strongest in patients that ate the most dietary fiber, but did not take probiotics, a finding that was replicated with lab animals.