CD274 and small cell lung carcinoma: Recently, however, phase 3 trials have revealed a substantial survival advantage for the addition of antibodies to programmed death-ligand 1 (PD-L1) to first-line chemotherapy for extensive-stage SCLC (ES-SCLC),5,6 although the benefit of this new treatment strategy is restricted to a small subset of patients, in part because of a limited understanding of both the disease and the key determinants of a response to immunotherapy.7