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 B-labeled compounds and neutron irradiation. The B(n,α)Li reaction produces a 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 B at metastatic lesion sites. In this study, we designed, synthesized, and evaluated [Ga]Ga-DOTA-K(ε--dodecaborate)D ([Ga]), a compound integrating -dodecaborate for BNCT, a [Ga]Ga-DOTA derivative for nuclear imaging, and D, an aspartic acid peptide, for bone targeting. [Ga] and its precursor , 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 [Ga] as an effective theranostic agent for bone metastases.