Evaluation of necessary conditions for neutron capture therapy using boronated antibodies

The application of blood-brain-barrier boronated compounds to neutron capture therapy, although demonstrating encouraging clinical results, does not permit large (>2-3) macroscopic tumor-to-blood boron concentration ratios to be achieved. The concept of employing boronated antibodies, specifically targeted toward certain tumor types, to transport boron to the desired cellular sites is superficially attractive. To determine whether such an approach is practically realistic, the authors have carried out a modeling study to examine the interplay of various physical and biochemical variables, such as neutron flux-depth and dose-depth distributions, antibody-antigen association constant, antigen site density, number of boron atoms per antibody molecule, and the amount of boron present in the blood pool, in their impact on the advantage depth (a criterion for therapeutic efficacy). It is concluded that given the pharmacodynamic properties of potentially useful antibody preparations, significant improvements in therapeutic efficacy over the currently available blood-brain-barrier compounds are not likely to be readily achieved