Bevacizumab for Recurrent Malignant Glioma

Background: Bevacizumab is a genetically engineered antibody that blocks the growth of new blood vessels in tumors. Inhibiting the formation of these blood vessels may slow or stop disease progression by diminishing the supply of life-sustaining nutrients and oxygen the blood delivers to the tumor. Bevacizumab is approved for treating colorectal cancer and has shown activity against brain tumor cells in laboratory and animal tests. Objectives: To examine the safety and side effects of bevacizumab in patients with recurrent brain tumors. To determine the anti-tumor activity of bevacizumab in patients with recurrent brain tumors. Eligibility: Patients 18 years of age and older with a brain tumor that continues to grow after receiving standard treatments. Design: Patients complete the following procedures during the study: * Infusions of bevacizumab through a vein once every 2 weeks in 4-week treatment cycles. * Positron emission tomography (PET) scan before the first dose of bevacizumab, at the end of the first treatment cycle, and as needed after that. * Magnetic resonance imaging (MRI) scan before the first dose of bevacizumab, within 48-96 hours after the first dose of bevacizumab in the first treatment cycle, and then every 4 weeks. One tube of blood for research is collected at the time of each MRI scan to look at specific cells. * Physical and neurological examinations every 2 weeks for the first treatment cycle and then every 4 weeks. * Quality-of-life questionnaires every 4 weeks.