CD274 and small cell lung carcinoma: However, So Yeon Oh et al. analyzed serum PD-L1 levels in patients with various solid tumors treated with ICI (ipilimumab), and they observed no relevant differences in soluble PD-L1 levels before and after immunotherapy in SCLC patients, thus excluding PD-L1 as a predictive biomarker of response to therapy with ipilimumab [61].