Furthermore, programmed death-ligand 1 (PD-L1) expression in tumor cells was found to be predictive of the response to PD-1 or PD-L1 inhibitors in the treatment of lung cancer, although some methodological problems (i.e., discordance between staining conditions, antibodies, fixation conditions, timing of biopsies, and cut-off values for positive vs. negative staining) were noted [11]. This evidence concerns the gene CD274 and neoplasm.