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. The gene discussed is PDCD1; the disease is cancer.