CD274 and neoplasm: It has been reported that on a biologic level, PD-L1 expression is a marker for activated CD8+ TILs, indicating that elevated levels are correlated to an enhanced immune response [101], whereas on the therapeutic level, T cells that were originally inhibited by PD-L1 would reactivate again after a PD-L1 blockade, inducing an anti-tumor immune response.