CTLA4 and cancer: Hence, cancer vaccines with ICBs may improve the clinical outcomes of patients with PC by activating T cells and inducing effective anti-tumor immunity because anti PD-1 can increase effector CD8+ T cells and secretion of IFN-γ in the TME, while vaccination could block the immunosuppressive pathways, inhibit immune-inhibiting T cells and reduce CTLA-4 expression on T cells.