Evaluating the Efficacy of Carborane-Monoclonal Antibody Conjugates in Boron Neutron Capture Therapy Using Particle and Heavy Ion Transport Code System (PHITS)

Abstract

Boron Neutron Capture Therapy (BNCT) offers a promising avenue for treating aggressive cancers by selectively targeting malignant cells while sparing healthy tissue. A key determinant of BNCT efficacy is the precise and sufficient accumulation of boron-10 (10B) atoms at the tumor site, a challenge that remains a major obstacle in BNCT. To address this, this study employs the Particle and Heavy Ion Transport Code System (PHITS) to investigate the feasibility of using a carborane-monoclonal antibody conjugate (CMAC) as a boron-delivery agent. This study integrates a carborane-based monoclonal antibody construct with Monte Carlo particle transport modeling to characterize secondary particle production and penetration behavior relevant to BNCT micro-dosimetry. In the simulation, a soft tissue phantom containing 25 ppm of 10B was irradiated with an epithermal neutron beam at 1.0 × 10⁻² MeV, yielding a neutron flux of 1.2 × 10⁹ cm⁻² s⁻¹. Monte Carlo analysis of the secondary particle fluence showed the production of α particles and 7Li ions with high linear energy transfer and subcellular penetration ranges, along with lower-energy photons with broader dispersion. These results suggest that CMAC may induce sufficient 10B(n,α)7Li reactions to achieve localized cytotoxic effects, indicating its potential viability as an effective boron-delivery agent for BNCT.