The density of tumoral CD8-positive tumor-infiltrating lymphocytes (TILs) was also investigated as a potential marker of response to anti-PD-1 therapy, and it was found that those with a high density of TILs responded significantly better to treatment (progression free survival: 12.9 months) than those with a low density of TILs (progression free survival: 1.3 months) [72]. This evidence concerns the gene PDCD1 and neoplasm.