Boron neutron capture therapy prolongs survival in a rat model of multifocal brain metastases

Boron neutron capture therapy (BNCT) is a tumor-selective radiation modality that delivers high-linear energy transfer alpha and Lithium-7 particles to boron-containing cells following neutron irradiation. While both preclinical and clinical investigations of BNCT for intracranial tumors have primarily focused on solitary lesions, brain metastases frequently present as multifocal disease in clinical practice. The therapeutic efficacy of BNCT in this setting remains insufficiently explored.

We evaluated the therapeutic efficacy of BNCT in rat models of solitary and multiple brain metastases established using a syngeneic breast cancer cell line. Boronophenylalanine was administered intravenously prior to neutron irradiation. Survival outcomes were compared among untreated controls, neutron irradiation alone, and BNCT groups. Boron biodistribution was analyzed to determine optimal irradiation timing, and treatment safety was assessed by longitudinal monitoring of body weight.

BNCT significantly prolonged post-irradiation survival compared with neutron irradiation alone and untreated controls in both solitary and multiple tumor models. Notably, a substantial survival benefit was maintained even in the multiple brain metastasis model, despite the presence of spatially distributed intracranial tumor burden. Biodistribution analysis demonstrated preferential boron accumulation in tumor tissue relative to normal brain. Body weight monitoring indicated no significant treatment-related toxicity.

BNCT demonstrated therapeutic efficacy and feasibility in a preclinical model of multiple brain metastases, providing a survival benefit without excessive toxicity. These findings support further investigation of BNCT as a potential treatment strategy for multifocal intracranial disease.