ION MICROSCOPY IMAGING OF B-10 FROM P-BORONOPHENYLALANINE IN A BRAIN-TUMOR MODEL FOR BORON NEUTRON-CAPTURE THERAPY

Boron neutron capture therapy (BNCT), a binary treatment modality that can potentially irradiate tumor tissue within cellular dimensions, is critically dependent on the preferential delivery of B-10 to individu al neoplastic cells, In this study, ion microscopy was used to quantit atively evaluate the selectivity of p-boronophenylalanine-fructose (BP A-F) in the rat 9L gliosarcoma brain tumor model. With a spatial resol ution of similar to 0.5 mu m, ion microscopy Images show that BPA-F de livers 3.5 times more boron to the main tumor mass [99 +/- 36 mu g/g t issue (mean +/- SD)] than to the contiguous normal brain (27 +/- 12 mu g/g tissue). A similar, but lower, accumulation was observed away fro m the main tumor mass in small clusters of neoplastic cells (47 +/- 15 mu g/g tissue) invading the surrounding brain (16 +/- 8 mu g/g tissue ), These findings establish for the first time the selectivity of BPA- F to the neoplastic cells invading the normal brain and provide a much -needed baseline measurement of the distribution of a clinically appro ved BNCT drug, Given the propensity for malignant brain tumors to infi ltrate the surrounding normal brain, these observations have particula r significance for clinical trials of BNCT for human glioblastoma mult iforme using the drug BPA-F.