Biodistribution ex vivo of 213Bi-KHEDP − a promising boneseeking agent for targeted alpha therapy

Abstract

Alpha-emitters are increasingly used for targeted alpha therapy because of their emission of high linear energy transfer (LET) particles with a relative short path length. Bismuth-213 (213Bi, T1/2 = 46 min) is one of the most suitable radiation sources for medical applications. In the present work the biodistribution of 213Bi-monopotassium salt of 1-hydroxyethylidene diphosphonic acid (213Bi-KHEDP) in intact mice was studied. It was shown that bones uptake of 213Bi-KHEDP were higher than in the most soft tissue organs throughout the study. The bone-to-soft tissue ratios for 213Bi-KHEDP were higher than the corresponding data for 213BiCl5. Among the soft tissue organs, only kidneys had a high uptake of Bi-KHEDP and free 213Bi. In conclusion, 213Bi-KHEDP had a strong and selective bone affinity, indicating that this complex could be useful to deliver alpha-particle radiation to primary bone cancer and skeletal metastases.