The activity of PD-1/PD-L1 axis is immunosuppressive: in particular, excessive induction of PD-1 pathway in the setting of chronic antigen exposure as well as in cancer has been shown to induce an exhausted or anergic phenotype in T cells [1, 2], thus impairing the antitumor activity of the immune system. This evidence concerns the gene PDCD1 and cancer.