Two cases of response to pembrolizumab in epidermal growth factor receptor mutated lung adenocarcinoma patients with programmed death-ligand 1 overexpression

Recently, the immune checkpoint inhibitor (ICI) pembrolizumab was demonstrated to be superior to platinum doublet chemotherapy in the first-line setting in patients with tumor programmed death-ligand 1 (PD-L1) expression of at least 50%. However, because patients with epidermal growth factor receptor (EGFR) mutations or anaplastic lymphoma kinase (ALK) rearrangements were not included in that study, the efficacy of pembrolizumab in lung cancers carrying EGFR mutations could not be determined. Here we describe two cases of response to pembrolizumab in EGFR mutated lung adenocarcinoma patients with PD-L1 overexpression. These cases indicate that ICI is an effective treatment for EGFR mutated lung adenocarcinoma patients with PD-L1 overexpression.