Abstract
Abstract Developing monoclonal antibodies labeled with beta-emitters has led to the introduction of important agents in radioimmunotherapy. In this work, Sc-46 chloride was obtained by thermal neutron activation flux of natural metallic scandium sample followed by dissolution in acidic media (radionuclidic purity via beta and gamma ray spectroscopy, 99.9% ; radiochemical purity via ITLC, >99%) and used in radiolabeling of rituximab after conjugation with DOTA-NHS-ester. The specific activity was however not high. The conjugates were purified by molecular filtration and used in the radiolabeling. The radiochemical purity (ITLC), stability studies (ITLC and size exclusion chromatography), determination of average number of DOTA conjugated per mAb (chelate: antibody ratio, 5.8:1) and gel electrophoresis of [ 46Sc]Sc-DOTA-anti-CD20 were determined followed by biodistribution studies for 46Sc and [ 46Sc]Sc-DOTA-anti-CD20 i n wild type rats up to 72 h. The binding of the radiolabeled antibody was showed to be 60% on Raji cells. The final compound was stable in presence of PBS at 37 ºC and room temperature. The accumulation of the radiolabeled antibody in liver, spleen, kidney, heart and other tissues demonstrates a pattern similar to the other radiolabeled anti-CD20 immunoconjugates. The present study shows the possibility of antibody labeling for future use in radioimmunotherapy by 47Sc.
Published Version
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