Emerging clinical principles on the use of bevacizumab for the treatment of malignant gliomas

Abstract

Despite advances in adjuvant therapy, the prognosis for most patients with high-grade glioma (HGG) is poor, and almost all HGGs have a likelihood of disease recurrence. HGGs are highly vascularized tumors with elevated expression levels of vascular endothelial growth factor (VEGF), an important mediator of angiogenesis. A compelling biologic rationale, a pressing need for improved therapeutics and positive results from studies of bevacizumab in other tumor types, led to the evaluation of bevacizumab in the treatment of HGG. It was demonstrated previously that bevacizumab, which is a humanized monoclonal antibody that targets VEGF, improved outcomes when combined with chemotherapy (most commonly irinotecan) in patients with recurrent HGG; and, on the basis of an improved objective response rate in 2 prospective phase 2 studies, bevacizumab was granted accelerated approval by the US Food and Drug Administration as a single agent in patients with previously treated glioblastoma (GB). Bevacizumab-containing therapy has been associated with manageable, class-specific toxicity; however, severe treatment-related adverse events are observed in a minority of patients. Preliminary data on bevacizumab-based therapy in recurrent anaplastic gliomas, in the frontline treatment of GB, and in additional patient populations are also encouraging. With the goal of addressing unanswered questions regarding the optimal use of bevacizumab, the objective of the current review was to provide a summary of the clinical efficacy and safety data on bevacizumab in patients with HGG, the practical issues surrounding the administration of bevacizumab, and ongoing investigations of bevacizumab in additional brain tumor treatment settings.