Radiolabeling Quality Control and Biodistribution Study of Anti-CD20 Antibody by 67Ga

Nowadays, anti-CD20 antibodies are being used in the therapy of lymphomas in free or radiolabeled form. Conjugation process was performed using native antibody and DOTA-NHS compound, synthesized in our laboratory. Thin layer chromatography and gel filtration were used to control the reaction progress as well as purification of the final antibody conjugate. 67GaCl3 produced at AMIRS was used to label the immunoconjugate and the reaction conditions were optimized for time, temperature and reactant concentrations. Quality control of the radioimmunoconjugate was performed using RTLC and gel filtration. The radiochemical purity was shown to be over 95%. The radioimmunoconjugate was used in the biodistribution studies up to 28 h and it was shown that after 24h most of the activity was accumulated in reticuloendothelial system consisting liver and spleen.