Theranostic Agent Targeting Bone Metastasis: A Novel [ 68 Ga]Ga/[ 177 Lu]Lu-DOTA-HBED-bisphosphonate.

Bone metastasis in cancer patients is a major disease advancement for various types of cancer. Previously, [ 68 Ga]Ga-HBED-CC-bisphosphonate ([ 68 Ga]Ga-P15-041) showed excellent bone uptake and efficient detection of bone metastasis in patients. To accommodate different α- or β - -emitting metals for radionuclide therapy, a novel DOTA-HBED-CC-bisphosphonate (P15-073, 1 ) was prepared and the corresponding [ 68 Ga]Ga- 1 and [ 177 Lu]Lu- 1 were successfully synthesized in high yields and purity. Gallium-68 conjugation to HBED-CC at room temperature and lutetium-177 conjugation to DOTA at 95 °C were verified in model compounds through secondary mass confirmation. These bisphosphonates, [ 68 Ga]Ga- 1 and [ 177 Lu]Lu- 1, displayed high binding affinity to hydroxyapatite in vitro . After an iv injection, it showed excellent uptake in the spine of normal mice, and micro-PET/CT imaging of nude mice model of bone metastasis showed high bone uptake in tumor tissue. The results indicated that [ 68 Ga]Ga/[ 177 Lu]Lu- 1 holds promise as a theranostic radioligand agent for managing cancer bone metastases.