Body Distribution and Occupational Dispersion of Scandium-47 Chloride: Safety Considerations for Radiopharmaceutical Development

This study investigated the distribution and dispersion of Sc-47 (47Sc), a β-emitting radionuclide that can be produced in large quantities using accelerators. As the stability of labeled compounds inside the body is essential for nuclear medicine therapy, we examined the biodistribution of free 47Sc to distinguish it from the distribution of compounds labeled with 47Sc. [47Sc]ScCl3 was administered to normal mice. Body distribution, excretion routes, and contamination of laboratory equipment were also measured. 47Sc remained in the blood for long periods and accumulated mainly in the liver and kidneys because of its binding to plasma proteins. Therefore, 47Sc released from the labeled compounds could potentially cause non-specific liver and kidney damage. Most of the 47Sc was eliminated through feces, whereas some was excreted through the urinary system. 47Sc was found in both the liquid and solid components of the blood. Although animal cages were contaminated with excreta, they could be effectively cleaned by wiping with paper. We also used 47Sc produced by us to label PSMA-617 and verified its performance as a nuclear medicine therapeutic agent. Although [47Sc]Sc-PSMA-617 did not exhibit a high accumulation rate in tumors, it demonstrated antitumor activity. This might suggest the usefulness of 47Sc.