Radioimmunotherapy of mice bearing breast tumors with 177Lu-labeled trastuzumab

Aim: In the present study, we investigated the therapeutic efficacy of trastuzumab labeled with lutetium-177 (177Lu) in mice bearing breast tumors. Materials and methods: Trastuzumab was labeled with 177Lu via DOTA as a chelator. In vitro and in vivo quality control tests of incorporated activity, immunoreactivity, stability of 177Lu–trastuzumab, biodistribution, and imaging studies were performed. Therapeutic efficacy and dosimetry studies were carried out in mice with breast tumors. Results: The good in vitro and in vivo quality control results suggested that 177Lu–trastuzumab could be used as a radioimmunotherapy agent. Reductions of 81% and 98% in the mean tumor volume for the group that received 177Lu– trastuzumab [7.4 MBq] were observed at 42 and 45 days after treatment, respectively. Conclusion: The results showed that 177Lu–trastuzumab could be considered as a possible new radiopharmaceutical agent for use in radioimmunotherapy of breast cancer in humans.