PDCD1 and renal cell carcinoma: Considering that it has been proposed that anti-PD-L1 antibodies activate PD-L1+ NK cells to control tumor growth [98] and that the mutated VHL gene induces PD-L1 expression in RCC cells [181], treating patients that have a high frequency of PD-L1+ NK cells with anti-PD-L1 rather than anti-PD-1 antibodies should be considered.