CD8A and neoplasm: The increased PD-L1 expression further impairs CD8+ T-cell function, promoting tumor immune escape and supporting tumor growth.190 (3) Copper ions contribute to tumor immune escape by upregulating the expression of CD274/PD-L1 (CD274 molecule), which serves as an immune checkpoint in cancer cells.191 (4) The disulfiram (DSF) and copper (DSF/Cu) complex upregulates PD-L1 expression by inhibiting poly (ADP-ribose) polymerase 1 (PARP1) activity and enhancing phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9 site, ultimately suppressing T cell infiltration.192