A Study of Bevacizumab Therapy in Patients With Newly Diagnosed High-Grade Gliomas and Diffuse Intrinsic Pontine Gliomas

Inclusion Criteria: * Patients must be ≥ 3 years of age and ≤ 30 years of age at the time of study entry. * Diagnosis: * High-grade glioma;Patients must have had histologically verified anaplastic astrocytoma, glioblastoma multiforme or gliosarcoma.Patients with primary spinal cord tumors are eligible. * Diffuse intrinsic pontine glioma (DIPG) are eligible. * Performance Level: Karnofsky ≥ 50% for patients \> 10 years of age and Lansky ≥ 50 for patients ≤ 10 years of age. Patients who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score. * Prior Therapy: no prior anticancer therapy. * Concomitant Medications: The use of steroids is permissible. * Organ Function Requirements All patients must have adequate organ function as defined below. * Adequate Bone Marrow Function * Adequate Renal Function * Adequate Liver Function * Adequate Blood Clotting Defined As: INR, Fibrinogen, and PTT \< Grade 2 * Central nervous system function. Patients with seizures may be enrolled if the seizures are well-controlled with non-enzyme inducing anticonvulsants. * Informed Consent. Patients and/or parents/legal guardians must have signed an informed consent. Exclusion Criteria: * Patients with metastatic disease (i.e. M+ disease, or disease anywhere other than primary site). * Patients with evidence of a new intracranial hemorrhage that is larger than a punctate size on baseline MRI scan. * Allergies: Patients with a history of allergic reaction to Chinese hamster ovary cell products, or other recombinant human antibodies. * Pregnant or breast feeding women will not be entered on this study. * Patients of childbearing or child-fathering potential must be willing to use a medically acceptable form of birth control, which includes abstinence, while being treated on this study. * Infection: Patients who require IV antibiotics at time of enrollment, or who are currently receiving treatment for Clostridium difficile infection are excluded. * Thrombosis: Patients must not have been previously diagnosed with a deep venous or arterial thrombosis (including pulmonary embolism), and must not have a known thrombophilic condition. * Serious or Non-Healing Wounds * Surgical Procedures: Patients who have had major surgery should not receive the first dose of bevacizumab until 28 days after major surgery. * Patients with uncontrolled systemic hypertension. * Proteinuria with a urine protein (albumin)/creatinine ratio of ≥1.0.