Development of a Theranostic Agent for Bone Metastases: Integration of Nuclear Medicine Imaging and Boron Neutron Capture Therapy (BNCT)

Boron neutron capture therapy (BNCT) is one of the promising cancer treatment methods with 10 B-labeled compounds and neutron irradiation. The 10 B(n,α) 7 Li reaction produces a 7 Li nucleus and an α-particle with high linear energy transfer, which are responsible for the therapeutic effects. We hypothesized that BNCT could effectively treat bone metastases by selectively accumulating 10 B at metastatic lesion sites. In this study, we designed, synthesized, and evaluated [ nat/67 Ga]Ga-DOTA-K(ε- closo -dodecaborate)D 11 ([ nat/67 Ga] 6 ), a compound integrating closo -dodecaborate for BNCT, a [ nat/67 Ga]Ga-DOTA derivative for nuclear imaging, and D 11 , an aspartic acid peptide, for bone targeting. [ 67 Ga] 6 and its precursor 5 , which lacks gallium coordination, showed comparable biodistribution in normal mice, with high bone uptake and minimal off-target accumulation. These results support the potential of [ nat/67/68 Ga] 6 as an effective theranostic agent for bone metastases.