Evidence supporting the role of the human gut microbiome in cancer prevention, Microbiota microorganisms such as Akkermansia muciniphila, Bifidobacterium spp., Faecalibacterium spp, and Bacteroides fragilis were shown to have regulatory effects on PD-1, PD-L1, and CTLA-4 blocked anticancer therapy outcome. This evidence concerns the gene CTLA4 and cancer.