Application of radioiodinated (2S,{alpha}S)-2-[{alpha}-(2-iodophenoxy)benzyl]morpholine to neuroendocrine tumor imaging.

1907 Objectives Neuroendocrine tumors are capable of causing severe disease due to the excessive secretion of a variety of hormones. Surgical resection and debulking offer the best palliation for those affected, but treatment is rarely curative due to the extent of the disease. It is much important to detect these tumors in the early stage. These tumors express norepinephrine transporters (NET). Recently, we developed radioiodinated (2S,αS)-2-[α-(2-iodophenoxy)benzyl]morpholine ((SS)-IPBM) as a NET imaging probe. In this study, we estimated the application of (SS)-[124I]IPBM to neuroendocrine tumor imaging. Methods Non-carrier added (SS)-[124I]IPBM was synthesized by a bromine-radioiodine exchange reaction. Using the neuroendocrine tumor cell lines (PC-12, SK-N-SH, BON), cell uptake studies were performed. Then, PET imaging studies were performed using PC-12 cell bearing nude mice. Results In cell uptake studies, (SS)-IPBM highly bound to these cell lines and these bindings were dose-dependently decreased to add a NET binding agent, desipramine. In PET studies, (SS)-IPBM clearly visualized tumor after 30 min post-injection. Moreover, the pre-treatment of desipramine suppressed the accumulation of (SS)-IPBM in tumors. These results suggested that (SS)-IPBM selectively bound to NET in tumors in vivo. Conclusions (SS)-[124I]IPBM can be applied to the neuroendocrine tumor imaging.