These data suggests that expression of PD-L1 at a certain level, even at a level of approximately 17% of cells, could sensitize cancer cells to PD-1/PD-L1 blockage, whereas even if up to about 50% of cells express PD-L1 in some tumors, such as 597-T1-3 and 607, their sensitivity remained low. This evidence concerns the gene PDCD1 and cancer.