Study identifies key drivers of microbiome-linked cancer immunotherapy side effect

University of Pittsburgh researchers report that 20%-40% of immune checkpoint inhibitor users experience related adverse events, and that diet and the gut microbiome can influence severity through regulatory T cell fragility. Combining a Western-diet mouse model, patient samples, and fecal microbiota transplantation, they found regulatory T cell fragility in patients with severe adverse events; in mice, blocking a signaling protein on regulatory T cells, switching to a high-fiber diet, or supplementing a metabolite each reduced severity.