PDCD1 and neoplasm: In the CT26 colon carcinoma mouse model, the combination therapy for anti-VISTA and anti-PD-L1 mAbs (VISTA-Ig and PD-L1 Ig) may induce 80% tumor regression by enhancing the response and increasing the count of T cells, boosting the antigen presentation and T cells’ activation [89], which may be attributed to the synergistic effect of VISTA and PD-1 in tumor immune regulation.