PDCD1 and colorectal carcinoma: Blocking VISTA with a monoclonal antibody could reverse the immunosuppressive activity, particularly in combination with anti-PD-1, leading to enhanced T cell infiltration, dampened expression of checkpoint receptors on T cells (PD-1, LAG-2, and TIM-3), and subsequent increased anti-tumor activity in MC38 colorectal carcinoma-bearing mice.