Despite the association between PD-L1 expression and clinical benefit from ICBs in diverse cancer types, a poor predictive value of PD-L1 expression by IHC has been reported in some cancers such as small cell lung cancer [15, 16], malignant melanoma [17, 18], hepatocellular carcinoma, and renal cell carcinoma [9]. This evidence concerns the gene CD274 and small cell lung carcinoma.