PDCD1 and colorectal cancer: Published studies explored the combination of single or dual CTLA4/PD-1 blockade together with DNA vaccines targeting the MYB oncoprotein for colorectal cancer [42], SSX2 cancer antigen for sarcoma [43], PSMA prostate-specific antigen, P815 mastocytoma [24] and TRP-2 and gp100 melanoma-specific antigens [44].