Avastin in Combination With Radiation (XRT) & Temozolomide, Followed by Avastin, Temozolomide and Irinotecan for Glioblastoma (GBM) and Gliosarcomas

Inclusion Criteria: * Patients must have histologically confirmed diagnosis of World Health Organization (WHO) grade IV primary malignant glioma (glioblastoma multiforme or gliosarcoma). Patients have to be within 4 weeks of the last major surgical procedure. * Age \> 18 years. * An interval of at least 2 weeks and not \> 6 weeks between prior major surgical procedure and study enrollment. * No prior radiotherapy or chemotherapy for a brain tumor * Karnofsky ≥ 60 percent. * Hemoglobin ≥ 9.0 g/deciliter (dl), absolute neutrophil count (ANC) ≥ 1,500 cells/ microliter, platelets ≥ 125,000 cells/microliter. * Serum creatinine ≤ 1.5 mg/dl, serum serum glutamic-oxaloacetic transaminase (SGOT) and bilirubin ≤ 1.5 times upper limit of normal (ULN). * For patients on corticosteroids, they must be on a stable or decreasing dose for 1 week prior to entry, and the dose should not be escalated over entry dose level, if clinically possible. * Signed informed consent approved by the Institutional Review Board * No evidence of \> grade 1 central nervous system (CNS) hemorrhage on the baseline MRI or CT scan. * If sexually active, patients will take contraceptive measures for the duration of treatment as stated in the informed consent. Exclusion Criteria: * Pregnancy or breast feeding. * Co-medication that may interfere with study results; e.g. immuno-suppressive agents other than corticosteroids. * Active infection requiring intravenous (IV) antibiotics. * Prior treatment with radiotherapy or chemotherapy for a brain tumor, irrespective of the grade of the tumor. * Evidence of \> grade 1 CNS hemorrhage on baseline MRI on CT scan. Avastin-Specific Concerns: Subjects meeting any of the following criteria are ineligible for study entry: * Current, recent (within 4 weeks of the first infusion of this study), or planned participation in an experimental drug study * Blood pressure of 150/100 mmHg * Unstable angina * New York Heart Association (NYHA) Grade II or greater congestive heart failure * History of myocardial infarction within 6 months * History of stroke within 6 months * Clinically significant peripheral vascular disease * Evidence of bleeding diathesis * Coagulopathy (prothrombin time (PT) or partial thromboplastin time (PTT) \>1.5x normal or a history of \> three grade 2 or greater hemorrhages) * Major surgical procedure, open biopsy, or significant traumatic injury within 28 days prior to first Avastin infusion during XRT/Temodar or anticipation of need for major surgical procedure during the course of the study * Minor surgical procedures, fine needle aspirations or core biopsies within 7 days prior to first Avastin infusion during XRT/Temodar * Pregnant (positive pregnancy test) or lactating * Urine protein \>1.0 + at screening * History of abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within 6 months prior to first Avastin infusion during XRT/Temodar * Serious, non-healing wound, ulcer, or bone fractures. * Inability to comply with study and/or follow-up procedures.