Development of a Theranostic Agent for Bone Metastases: Integration of Nuclear Medicine Imaging and Boron Neutron...

Boron neutron capture therapy (BNCT) is one of the promising cancer treatment methods with ¹⁰B-labeled compounds and neutron irradiation. The ¹⁰B(n,α)⁷Li reaction produces a ⁷Li 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 ¹⁰B at metastatic lesion sites. In this study, we designed, synthesized, and evaluated [^nat/67Ga]Ga-DOTA-K(ε-closo-dodecaborate)D₁₁ ([^nat/67Ga]6), a compound integrating closo-dodecaborate for BNCT, a [^nat/67Ga]Ga-DOTA derivative for nuclear imaging, and D₁₁, an aspartic acid peptide, for bone targeting. [⁶⁷Ga]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/67/68Ga]6 as an effective theranostic agent for bone metastases.