The results of the present study showed that negative tumor PD-L1 expression in patients with EGFR-mutant NSCLC as evaluated using the 22C3 antibody was associated with a longer PFS and a higher proportion of acquisition of T790M after first-line treatment with an EGFR-TKI in patients with EGFR-mutant NSCLC. This evidence concerns the gene EGFR and non-small cell lung carcinoma.