Preparation of ¹⁷⁷Lu-DOTA/DTPA-Bz-Cys-RGD Dimer and  Biodistribution Evaluation in Normal Mice

¹⁷⁷Lu-DOTA-Bz-Cys-RGD dimer and ¹⁷⁷Lu-DTPA-Bz-Cys-RGD dimer were prepared, and the in vitro and in vivoproperties were compared. TLC and HPLC show that the labeling yields of two radiolabeled compounds are more than 95% under optimal conditions (pH=5.0, reacting at 100 ℃ for 15~20 min), and the two radiolabeled compounds show pretty good in vitro stability. HPLC analyses and lg P values reveal that lipophilicity of ¹⁷⁷Lu-DOTA-Bz-Cys-RGD dimer is higher than ¹⁷⁷Lu-DTPA-Bz-Cys-RGD dimer. The uptake of ¹⁷⁷Lu-DTPA-Bz-Cys-RGD dimer in other tissues is significantly higher than that of ¹⁷⁷Lu-DOTA-Bz-Cys-RGD dimer at 4 h postinjection, except for blood and spleen. The in vivostability of ¹⁷⁷Lu-DOTA-Bz-Cys-RGD dimer is much better than ¹⁷⁷Lu-DTPA-Bz-Cys-RGD dimer. Bz-DOTA is an ideal bifunctional chelator for ¹⁷⁷Lu labeling of RGD dimer.