CD274 and melanoma: The expression of PD-L1 is normally increased in an inflammatory microenvironment to down-regulate ongoing immune activation, but this mechanism is hijacked by tumor cells to specifically inhibit T-cell effector functions.49 Taube et al.50 showed that PD-L1+ melanomas correlated with increased PD-1+ expression in TILs and were generally associated with improved long-term survival with anti-PD-1 therapy.