Modificación del hR3 con DOTA-NHS. Marcaje con 90Y y biodistribución.

In this work the conjugation, characterization and biodistribution of radioimmunoconjugate 90Y-DOTA-hR3 is reported. Acid 1, 4, 7, 10 tetraazacyclicdodecane N, N', N'' N''' tetraacetic ligand (DOTA-NHS) was used as bifunctional chelating agent. Molar ratios 320:1, 160:1 and 88:1 DOTA-NHS/monoclonal antibody (hR3) was studied for evaluating their influence on the integrity of conjugate and labeling efficiency. The characterization of conjugates formed was performed using HPLC and SDS-PAGE electrophoresis and isoelectric focusing. Determining the number of DOTA-NHS groups bound to a monoclonal antibody molecule was performed using the radioactive indicators method. In vivo stability of 90Y-DOTA-hR3 radioimmuneconjugates was determined in healthy Wistar rats at 4, 24 and 48 hours. Characterization for HPLC and electrophoresis showed that purity, identity and integrity of biomolecule, after the conjugation process was kept, and the molar ratio have an influence not only on the conjugation process but also on the labeling efficiency. It was more than 90% for molar ratios of 320:1 and 160:1. The specific activity of 90Y-DOTA-hR3 was between 2 and 13 mCi / mg. Stability studies performed by DTPA versus challenge showed that the compound is stable in a wide range of time (up to 216h). In vivo stability studies, based on the uptake in bone (taken into account the affinity of the 3+ metals for phosphates groups) showed that the lost of radiometal in the radioimmuneconjugate is not appreciable up to 48 hours. This study suggests that 90Y-DOTA-hR3 could be a potential candidate for use in radioimmunetherapeutic procedures. [ABSTRACT FROM AUTHOR]