Preparation of 211At-Labeled Humanized Anti-Tac Using 211At Produced in Disposable Internal and External Bismuth Targets

Abstract

These studies describe the production and purification of 211At as well as the procedure for labeling humanized anti-Tac, the antibody to the α-chain of the IL-2 receptor (IL-2Rα), which has been shown to be a useful target for immunotherapy. The optimized protocol combines the advantages of the two-stage dry distillation procedure with the astatination of trialkylstannyl substances as labeling compounds for proteins. The 211At was produced by bombarding either an external or a recently developed disposable internal bismuth target with α-particles from a Cyclotron Corporation CS-30 cyclotron. The 211At was found to contain less than 0.01% 210At. The production rate for the external target was 0.15 mCi ± 0.056 μA −1 h −1 ( n = 9) (5.55 MBq μA −1 h −1). The production rate for the internal target was 0.44 ± 0.14 mCi μA −1 h −1 ( n = 16) (16.28 MBq μA −1 h −1).