Comparative evaluation of radionuclide therapy usingY andLu.

Abstract

OBJECTIVE: BothY andLu are attractive β-emitters for radionuclide therapy and have been used in clinical practice. Nevertheless, comparative evaluation betweenY- andLu-labeled molecules has not been fully conducted. Thus, in this study, the features ofY andLu for radionuclide therapy were assessed in tumor-bearing mice. METHODS: Two tumor cell lines with different growth rates were used. Biodistribution studies ofLu-labeled antibodies (Lu-Abs) were conducted in each tumor-bearing mouse model. Subsequently, the therapeutic effect ofY- andLu-Ab were assessed in tumor-bearing mice. The absorbed radiation dose for the tumor was estimated using the Monte Carlo simulation. RESULTS: Lu-Abs demonstrated high tumor accumulation in both tumor-xerograph. In the fast-growing tumor model,Y-Ab showed a better therapeutic effect thanLu-Ab, reflecting a higher absorbed radiation dose ofY-Ab than that ofLu-Ab. In the slow-growing tumor model, bothY- andLu-Ab showed an excellent therapeutic effect; however,Lu-Ab had a longer efficacy period thanY-Ab, which could be attributed to the longer half-life and better dose uniformity ofLu than those ofY. CONCLUSIONS: To accomplish a maximum therapeutic effect, selectingY orLu, to depend on the growth rate of individual cancer, would be helpful.