Cell Type Selective Accumulation of Mercaptoundecahydro- Closo-dodecaborate (BSH) in Glioblastoma Multiforme

Background: Boron uptake in glioblastoma tissue for boron neutron capture therapy is of great importance for the clinical outcome of the treatment.

Methods: The cell type specific distribution of mercaptoundecahydro-closo-dodecaborate (BSH) in glioblastoma multiforme tissue sections of seven patients having received BSH prior to surgery was investigated by light and fluorescence microscopy.

Findings: With use of specific antibodies against different tumour specific epitopes and BSH, BSH was found predominantly (approx. 90%) in the cytoplasm of GFAP-positive cells of all but two patients. The latter were younger (33 and 38 years versus 46-71 (mean 60) years). There was no correlation between BSH uptake and expression of EGFR, p53, CD44 and Ki-67.

Interpretation: GFAP-positive cells appear to be the primary cell type for BSH uptake in primary glioblastoma, and an important cell type for localisation of BSH in secondary glioblastoma. The molecular basis and the selective uptake mechanism require further work. If a correlation between histologically distinct patterns and clinical outcome for patients undergoing boron neutron capture therapy could be derived, prognostic factors for the treatment could be developed.