Anti-PD-1 therapy is known to stimulate PD-L1 expression in cancer cells, and subsequently induce resistance to Fas or staurosporine-mediated apoptosis, and protect them from the cytotoxic effects of type I and II interferons or the cytotoxic T lymphocyte (CTL)-mediated lysis [61, 62]. This evidence concerns the gene PDCD1 and cancer.