Pre-Therapeutic Dosimetry Employing Scandium-44 for Radiolabeling PSMA-617

Abstract

In recent years, the positron emitter scandium-44 moved into the focus of research pro- viding favorable nuclide properties for an application in nuclear medicine. Radiolabeling of PSMA-617 with scandium-44 as diagnostic match for [ 177 Lu]Lu-PSMA-617 instead of gallium-68 would enable pre-therapeutic dosimetry in clinical setting. Due to the chemical similarities of scandium and lutetium, the in vitro and in vivo characteristics of [ 177 Lu]Lu-PSMA-617 are more similar to [ 44 Sc]Sc-PSMA-617 than to the 68 Ga-compounds [ 68 Ga]Ga-PSMA-617 or [ 68 Ga]Ga-PSMA-11. [ 44 Sc]Sc-PSMA-617 showed its potential in a clinical setting as a PET imaging agent of prostate cancer providing several advan- tages over gallium-68 labeled tracers. The longer half-life of the nuclide would allow, for example, an optimized patient management and treatment, long-term or late time point imaging as well as transportation to more distant PET centers. However, especially clinical applications like individual dosimetry or intraoperative applications are still under investigation.