CD274 and small cell lung carcinoma: KEYNOTE-028 is a phase Ib multi-cohort, open-label trial that investigated the efficacy and safety of pembrolizumab, a PD-1 inhibitor, in recurrent SCLC with PD-L1 positive tumors, showing promising results in patients with pre-treated SCLC, with one patient out of 24 recruited achieving complete response and an ORR reaching 33% (95% CI of 16–55%).