CD274 and melanoma: Recently, a link between PD-L1 expression, tumor mutational burden (TMB) and/or microsatellite instability with the response to iCPIs has been reported in different tumor types, including, e.g., non-small lung cell carcinoma (NSCLC), melanoma, renal cell carcinoma (RCC) and colorectal cancer (CRC) [10,11].