Boron neutron capture radiation therapy of cerebral gliomas: an analysis of the possible use of boron-loaded tumor-specific antibodies for the selective concentration of boron in gliomas.

The possibility of achieving a therapeutically useful tissue boron distribution for boron neutron capture therapy (BNCT) of cerebral gliomas with boron loaded tumor-specific antibodies is discussed. Using a theoretical tumor-immunological model and RBE dose-depth calculations, the effects of various parameters, e.g. antibody-antigen association constant, antigen site density, number of boron atoms per antibody molecule, etc., on the advantage depth, a relative measure of the resulting radiation dose distributions, are determined. It is shown that with this model a maximum in the advantage depth as a function of the blood boron concentration occurs, the position of which is dependent on the value of the parameters used. Frequently this maximum corresponds to a blood boron-10 concentration range of between 0.1 to 0.5 microgram 10B/g blood. It is concluded that given the pharmacodynamic properties of potentially useful antibody preparations for this type of tumor therapy, advantage depths significantly greater than those obtainable with existing "blood-brain-barrier" compounds are not likely to be easily achieved.