▪The microbiome comprises all genetic material within a given microbiota. ▪The gut microbiome influences the efficacy of PD-1 treatment in epithelial tumors. ▪Blood microbiome composition were determined according to tumor response and clinical benefit with anti-PD-L1.▪Disadvantages: few studies, larger sample sizes needed for statistical validity, high cost. Here, PDCD1 is linked to neoplasm.