In the phase I, multicohort KEYNOTE-028 study, patients with PD-L1-positive recurrent or metastatic SCLC who received pembrolizumab monotherapy achieved an objective response rate (ORR) of up to 33.3%, with a median OS of 9.7 months (95% CI 4.1-not reached), indicating promising antitumor activity of pembrolizumab in PD-L1 positive SCLC patients [43]. This evidence concerns the gene CD274 and small cell lung carcinoma.