Biodistribution of Osteotropic 177Lu-EDTMP – a Potential Radiopharmaceutical for Radionuclide Therapy of Bone Metastases

Phosphonates labeled with beta-emitting radionuclides are widely used in nuclear medicine for palliative therapy of bone metastases. This work was aimed at studying the biodistribution of a new osteotropic antitumor agent based on N,N,N′,N′-ethylenediaminetetrakis(methylenephosphonic acid) labeled with 177Lu (177Lu-EDTMP) in intact animals. The biodistribution in vivo in intact Wistar rats of free Lu in the form of 177LuCl3 was also investigated to assess the stability of 177Lu-EDTMP. It was found that 177Lu-EDTMP accumulated mainly in the skeleton (22.67 – 54.89% of the injected dose) with minimal uptake in other organs and tissues. The amount of 177LuCl3 in bone did not significantly differ from 177Lu-EDTMP uptake but the concentration of 177LuCl3 in soft organs was significantly higher (p < 0.05) as compared to that of 177Lu-EDTMP. The results indicated that further studies of 177Lu-EDTMP in clinical application for therapy of skeletal metastases had good prospects. © 2022, Springer Science+Business Media, LLC, part of Springer Nature.