Nowadays, PD-L1 expression (at different cut-offs) is determined only to select metastatic NSCLC candidates to be treated with pembrolizumab both in first and second line, since a clear association between PD-L1 positive tumors and an enhanced clinical benefit with this anti PD-1 antibody was detected in pivotal studies (9, 11). This evidence concerns the gene PDCD1 and non-small cell lung carcinoma.