Although higher rates of irAEs than anti-PD-1 or anti-CTLA-4 monotherapy, responders to combined ICB therapy targeting both CTLA-4 and PD-1 and responders to monotherapy exhibited similar compositional characteristics of gut microbiota with an enrichment of Ruminococcus/Ruminococcaceae consistently observed across diverse melanoma cohorts (41). This evidence concerns the gene CTLA4 and melanoma.