Boron Neutron Capture Therapy Against Tumor Cells with Overexpression of the EGF-Receptor

The binary nature of boron neutron capture therapy, BNCT, is an advantage because the tumor-seeking substance can be activated at any chosen time and because the neutron field can be delivered to selected areas so that exposure of critical healthy organs, which might contain significant amounts of boron, can be avoided. The tumor selective action should work in spite of the fact that tumor cells often have an infiltrative growth pattern being mixed with populations of normal cells. The targeting principle should be based on well-characterized properties of the tumor cells such as appearence of tumor-associated antigens or overexpression of receptors. The targeting agent could be antibodies, antibody-fragments or receptor ligands. Presently, mainly monoclonal antibodies are considered as targeting substances but it has been claimed that current approaches are limited by low uptake in the tumors studied. Thus, it seems necessary to also consider other principles such as growth factor mediated targeting (1–4).