Background & Objectives: Antibody-based radiopharmaceutical drugs are the great current interest in imaging and radiotherapy of cancers, and provide an important tool for target-specific delivery of radionuclides to specific antigens in the diseased tissues. The monoclonal antibody avastin binds, neutralizes VEGF (Vascular endothelial growth factor) and blocks VEGF-induced angiogenesis in tumor tissues. In this study, the complex of avastin and beta particle was investigated as a first step in the production of a radiopharmaceutical drug.

  Methods: Antibody of avastin was prepared and purified. The antibody was conjugated with freshly prepared DOTA-NHS and then labeled with ¹⁵³Sm-samarium chloride (185 MBq). The efficiency and in vitro stability of antibody labeling were determined using thin layer chromatography. The integrity of the radiolabeled antibody was checked by SDS-PAGE (Sodium Dodecyl Sulfate PolyAcrylamide Gel Electrophoresis) protocol. Biodistribution study of ¹⁵³Sm-DOTA –Avastin was performed in BALB/c mice at 2, 24, 48 and 72 hours after injection.

  Results: The efficiency of antibody labeling was more than 98%. The in vitro stability of the labeled product in human serum after 120h was 83 ±2%. There was no fragmentation in the labeled antibody during SDS-PAGE protocol. The highest (%ID/g) was observed in the liver, lungs and kidneys.

  Conclusion: The monoclonal antibody avastin against angiogenesis was effectively radiolabeled with ¹⁵³Sm. The Biodistribution study showed that it has a high specificity to accumulation in tissues with enriched blood vessels.