CD274 and small cell lung carcinoma: In addition, a total of 54 ES-SCLC patients received ICIs combined with chemotherapy as the first-line treatment were retrospective reviewed form January 2013 to December 2021, of which 34 patients treated with EP/EC combined with a PD-L1 inhibitor (atezolizumab or durvalumab) were selected as the historical control group.