Comparative evaluation of radionuclide therapy using 90 Y and 177 Lu.

Objective: Both ⁹⁰ Y and ¹⁷⁷ Lu are attractive β-emitters for radionuclide therapy and have been used in clinical practice. Nevertheless, comparative evaluation between ⁹⁰ Y- and ¹⁷⁷ Lu-labeled molecules has not been fully conducted. Thus, in this study, the features of ⁹⁰ Y and ¹⁷⁷ Lu for radionuclide therapy were assessed in tumor-bearing mice.
Methods: Two tumor cell lines with different growth rates were used. Biodistribution studies of ¹⁷⁷ Lu-labeled antibodies ( ¹⁷⁷ Lu-Abs) were conducted in each tumor-bearing mouse model. Subsequently, the therapeutic effect of ⁹⁰ Y- and ¹⁷⁷ Lu-Ab were assessed in tumor-bearing mice. The absorbed radiation dose for the tumor was estimated using the Monte Carlo simulation.
Results: ¹⁷⁷ Lu-Abs demonstrated high tumor accumulation in both tumor-xerograph. In the fast-growing tumor model, ⁹⁰ Y-Ab showed a better therapeutic effect than ¹⁷⁷ Lu-Ab, reflecting a higher absorbed radiation dose of ⁹⁰ Y-Ab than that of ¹⁷⁷ Lu-Ab. In the slow-growing tumor model, both ⁹⁰ Y- and ¹⁷⁷ Lu-Ab showed an excellent therapeutic effect; however, ¹⁷⁷ Lu-Ab had a longer efficacy period than ⁹⁰ Y-Ab, which could be attributed to the longer half-life and better dose uniformity of ¹⁷⁷ Lu than those of ⁹⁰ Y.
Conclusions: To accomplish a maximum therapeutic effect, selecting ⁹⁰ Y or ¹⁷⁷ Lu, to depend on the growth rate of individual cancer, would be helpful.
(© 2022. The Author(s) under exclusive licence to The Japanese Society of Nuclear Medicine.)