PD-L1 expression is widely used today for the selection of anti-PD-1 therapy in patients with non-small cell lung cancer and melanoma [141,142]; as for HCC, this association has not yet been sufficiently investigated and PD-L1 expression cannot be considered a binary marker to help decide which patients should receive anti- PD-1 therapy. This evidence concerns the gene PDCD1 and non-small cell lung carcinoma.