Wet harvesting of no-carrier-added 211At from an irradiated 209Bi target for radiopharmaceutical applications

Abstract

Astatine-211 is one of the most promising α-emitters for targeted cancer radiotherapy. However, research and clinical trials involving 211At-labeled radiopharmaceuticals have often been impeded due to the irregular and sometimes inconveniently low recovery yields obtained by the currently used dry distillation procedure. Therefore, a wet harvesting procedure isolating 211At from an irradiated 209Bi target was explored. The procedure involves target dissolution in concentrated HNO3 and extraction of the high oxidation state 211At activity with butyl or isopropyl ether. This method resulted in consistent and nearly quantitative yields. The activity was re-extracted in aqueous phase and applied to NIS6 UVW human glioma cells transfected with cDNA encoding the human sodium/iodide symporter (NIS). The significant and specific uptake of 211At activity by these cells suggests that in the ether phase, high oxidation state 211At is reduced to [211At]astatide anion. The synthesis of the first astatinated organic compound derived from wet harvested 211At, 3-astatobenzoic acid (ABA), was achieved.