Synthesis and biodistribution studiesof 177Lu‐trastuzumab as a therapeutic agent in the breast cancer mice model

Abstract Trastuzumab is a humanized monoclonal antibody against the HER2 that has the potential to be used as radioimmunotherapy (RIT) agent in treatment of breast cancer. Lutetium‐177 has beta energy suitable for therapy and gamma photons for imaging. We labeled trastuzumab with lutetium‐177 via DOTA as chelator and performed some necessary tests for the first stage in using complex as a RIT agent. Radiochemical purity, immunoreactivity and stability of complex were determined. The biodistribution and imaging studies were determined in mice bearing breast tumor. The radiochemical purity was 94±0.9%. Lutetium‐Trastuzumab showed a good stability at biological condition. The tumor to blood ratio was calculated 3.29(±0.09) after 7 days. The good tumor uptake in biodistribution studies was agreed with gamma camera images after 7 days. The results showed that the new complex could be considered for further evaluation in animals and possibly in humans as a new radiopharmaceutical for use in RIT against breast cancer. Copyright © 2010 John Wiley & Sons, Ltd.