Together, the immunotoxin imaging results here demonstrate that CDH17 Nb E8 can specifically deliver inactive toxin PE38mut in tumors positive for CDH17 expression, implicating that, therefore, active immunotoxin, E8-PE38, can efficiently home to CDH17-positive CRC tumors and execute in vivo antitumor functions. This evidence concerns the gene CDH17 and colorectal carcinoma.