Although sPD-L1 was considered as a potential marker for poor prognosis in patients with SCLC treated with chemotherapy (179), the analysis of sPD-L1 levels in patients with various solid tumors treated with ICI (Ipilimumab) revealed no relevant differences in sPD-L1 levels before and after immunotherapy in patients with SCLC, excluding sPD-L1 as a predictive biomarker of response to therapy with Ipilimumab (178). Here, SPDL1 is linked to small cell lung carcinoma.