Aim and Background: Herceptin is a human monoclonal antibody that is being used in treatment of the breast cancer. In this study, this monoclonal antibody was labeled with lutetium-177 via PA-DOTA chelator and at the first stage its therapeutic effects on SKBR3, MCF7 and A431 breast cancer cell lines was investigated.

Material and Methods: The in vitro quality control tests included labeling efficiency, immunoreactivity, in vitro stability in buffer and blood serum were performed .The cytotoxicity effect of the complex was considered upon 168 hours on the SKBR3, MCF7 and A431 breast cancer cell lines.

Results: The labeling efficiency was 85±5%. The stability in phosphate buffer and human blood serum was 73±5% and 65±3% respectively up to 96 hours. The immunoreactivity of the complex was 72± 8%. It was calculated 5 folds increasing in toxicity of Herceptin-177Lu compared with unlabeled Herceptin on SKBR3 cells.

Conclusion:The results showed that this new complex could be a promising candidate for further evaluation in animals and possibly in humans as a new radiopharmaceutical for use in radioimmunotherapy of breast cancer.