Exploratory analysis performed in the SCLC cohort of KEYNOTE-158 has shown the potential of the PD-L1 combined score, i.e., the ratio of PD-L1-positive cells, including tumor cells, lymphocytes, and macrophages, to the total number of tumor cells, but further validation is necessary before this is incorporated to the standard-of-care [20]. This evidence concerns the gene CD274 and neoplasm.