CEACAM5 and colorectal cancer: The [64Cu]Cu-DO3A-VS-M5A∆CH2-C5 was evaluated for its ability to target CEA-positive tumors in two colorectal cancer mouse models: 1) athymic mice bearing human colorectal cancer LS174T xenografts and 2) immunocompetent CEA-transgenic mice bearing murine colorectal cancer MC-38 cells transfected with human CEA (CEA is only expressed in higher primates, requiring CEA gene transfection) [6, 14].