EGFR and neoplasm: Given that immune mechanisms are involved in EGFR-TKI resistance and that increased PD-L1 expression has been detected in the context of acquired resistance to EGFR-TKIs [30, 31], it is assumed that PD-L1 expression on tumor and immune cells may predict poor response to EGFR-TKI treatment in NSCLC patients with EGFR mutation.