Biomarker studies revealed a significant correlation between the pretreatment expression level of the PD-1 ligand PD-L1 in tumor cells (as determined by immunohistochemical analysis) and the likelihood of a response to PD-1 inhibitors, whereas EGFR mutations appear to be a negative predictive factor for PD-1 inhibitor efficacy. This evidence concerns the gene EGFR and neoplasm.