44/47 Scandium Labelled Cholecystokinin Derivative for Cancer Theragnostics

Abstract The cholecystokinin (CCK) receptors are known to overexpress in various types of tumors. Through a previous study, a cyclic CCK analogue, DOTA-[Nle]-cCCK, was confirmed to have high in vivo stability and the tumor target ability of DOTA-[Nle]-cCCK capable of binding to the CCK receptor was confirmed through Lu-177 labeling. In this study, DOTA-[Nle]-cCCK was labeled with the pair-isotope, Sc-44/47, to confirm a technology that possibly could be applicable to radiopharmaceutical. First, we confirmed that the CCK receptor was overexpressed in AR42J, a cancer cell overexpressed in cancer tissue, and measured the binding ability of the receptor and DOTA-[Nle]-cCCK. We established the labeling method of radioactive scandium, and we confirmed that the Sc-44 labeled DOTA-[Nle]-cCCK administered to mice remained mostly in the bladder within an hour. Cell experiments with Sc-47 labeled DOTA-[Nle]-cCCK confirmed that more than half of the cancer cells were killed at a concentration of 5 MBq/ml. Through this study, we were able to confirm the diagnostic/therapeutic applicability of the DOTA-[Nle]-cCCK label with pair-isotope Sc-44/47.