A 73-year-old woman with epidermal growth factor receptor (EGFR) L858R-mutant lung adenocarcinoma (cT4N1M1a stage IV, programmed death-ligand 1 (PD-L1) high expression (60%)) received osimertinib as first-line therapy, but disease progression was observed after two months. This evidence concerns the gene CD274 and lung adenocarcinoma.