Radiolabeling of trastuzumab with super(177)Lu via DOTA, a new radiopharmaceutical for radioimmunotherapy of breast cancer

Aim - Trastuzumab is a monoclonal antibody that is used in treating breast cancer. We labeled this monoclonal antibody with lutetium-177 and performed in vitro quality control tests as a first step in the production of a new radiopharmaceutical. Material and Methods - Trastuzumab was labeled with lutetium-177 using DOTA as chelator. Radiochemical purity and stability in buffer and human blood serum were determined using thin layer chromatography. Immunoreactivity and toxicity of the complex were tested on MCF7 breast cancer cell line. Results - The radiochemical purity of the complex was 96+/-0.9%. The stabilities in phosphate buffer and in human blood serum at 96 h postpreparation were 93+/-1.2% and 85+/-3.5%, respectively. The immunoreactivity of the complex was 89+/-1.4%. At a concentration of 1 nM, the complex killed 70+/-3% of MCF7 cells. At 1.9 nM, 90+/-5% of the cells were killed. Conclusions - 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 radioimmunotherapy against breast cancer.