HER-2/neu expression in glioblastoma multiforme (GBM)

Abstract

e13035 Background: Glioblastoma multiforme (GBM) is a disease in which very few cytotoxic chemotherapy agents have been shown to have activity. This is partly due to their inability to cross the blood brain barrier. Trials with bevacizumab, a VEGF inhibitor that disrupts tumor angiogenesis, have demonstrated activity against this otherwise chemotherapy resistant disease. This has led to interest in other biologic agents that target angiogenic pathways for the treatment of GBM. Over-expression of HER-2/neu by human tumor cells is closely associated with increased angiogenesis and expression of VEGF. Lapatinib is a recently available low molecular weight immunotherapeutic agent that targets HER-2/neu proteins. In a recent study, breast cancer patients treated with lapatinib and capcitabine had decreased brain metastases indicating that lapatinib may cross the blood brain barrier and thus have potential in the treatment of malignant gliomas. Limited studies have evaluated HER-2/neu gene expression in GBM and the results are inconsistent. We evaluated the expression of Her-2/neu protein in 41 consecutive GBM cases to explore the potential utility of targeting this pathway. Methods: Archival histopathologic sections from 41 patients (age 26–89 years) with a diagnosis of GBM from 2004–2008 were reviewed. The diagnosis was confirmed and optimal sections were selected. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue sections using the primary antibody against HER-2/neu (clone 4B5, Ventana). The results were evaluated by three independent investigators. Interpretation was performed using the semi-quantitative criteria (Score 0 to 3+) currently used for primary breast carcinomas. Results: 38 out of 41 cases showed no immunohistochemical staining with HER-2/neu antibody (score 0). Three cases demonstrated weak, incomplete membrane staining of rare tumor cells (score 1+) and were interpreted as negative. The positive and negative controls worked properly. Conclusions: Our study indicates that there is no significant immunohistochemical over-expression of HER-2/neu protein in GBM. This suggests that HER-2/neu over-expression is not a significant oncogenic pathway in GBM, and therefore may not be a potential therapeutic target in this disease. No significant financial relationships to disclose.