MPC-1 Immunohistological Comprehensive Analysis of Angiogenic Factors Other Than Vegf in Glioblastomas in Relation to the Use of Bevacizumab

Abstract

To date, few clinical observations have been reported for changes of alternative angiogenic factors (other than vascular endothelial growth factor [VEGF]) in human gliomas under bevacizumab (Bev). The elucidation of the mechanism of action and resistance is imperative to overcome resistance to Bev and develop a more effective therapy. This study aims to investigate the status and change of alternative angiogenic factors regarding Bev usage.The present study used 56 glioblastoma tissues obtained at 3 different settings: tumors of initial resection (naive Bev group), tumors resected following Bev therapy (effective Bev group), and recurrent tumors after Bev therapy (refractory/autopsied Bev group). The expression of alternative angiogenic factors including basic fibroblast growth factor (bFGF), placental growth factor (PlGF), Angiopoietin1 (Ang-1), Angiopoietin2(Ang-2) and EphrinA2 were investigated via immunohistochemistry. In large tumor vasculature (diameter >15μm), the expression of PlGF was significantly higher in the effective Bev group than naive Bev group. The expression of Ang-2 was persistently suppressed in the refractory/autopsied Bev group. In microtumor vasculature (diameter <15μm), the expression of Ang-2 was higher in the effective group than naive Bev group. The status of PlGF was similar among these three groups.We provide the first clinicopathological evidence of the status of alternative angiogenic pathway after the Bev usage. These in situ observations will help to optimize therapy.