A Study of Gliadel Followed by Avastin + Irinotecan for Glioblastoma Multiforme (GBM)

Inclusion Criteria: * Patients must have histologically confirmed diagnosis of WHO grade IV primary malignant glioma (glioblastoma multiforme or gliosarcoma). Patients have to be able to undergo a GTR. * Age \> or = 18 years * Evidence of a unilateral, single focus of measurable central nervous system (CNS) neoplasm on contrast-enhanced MRI, unless medically contraindicated (CT scan will then be used) * Patients must have \< or = 2 disease progressions * An interval of at least 4 weeks from the end of prior radiotherapy or one week from the end of a cycle of chemotherapy and enrollment on this protocol * Karnofsky \> or = 70% * Hemoglobin \> or = 9.0 g/dl, absolute neutrophil count (ANC) \> or = 1,500 cells/microliters, platelets \> or = 125,000 cells/microliters * Serum creatinine \< or = 1.5 mg/dl, serum glutamic-oxaloacetic transaminase (SGOT) and bilirubin \< or = 1.5 times upper limit of normal * Patients on corticosteroids must have been on a stable dose for 1 week prior to entry, if clinically possible, and the dose should not be escalated over entry dose level * If patient received chemotherapy or investigational agent as part of their prior therapy, the patient must recover from all toxicities (\> or = Grade 1) prior to enrollment on this protocol * Signed informed consent approved by the Institutional Review Board * No evidence of CNS hemorrhage on the baseline MRI or CT scans * 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. Women of childbearing potential must have a negative serum pregnancy test within 72 hours prior to treatment administration * Multifocal disease * Prior treatment with Gliadel * Prior treatment with CPT-11 or Avastin * Prior stereotactic radiosurgery or brachytherapy * Co-medication that may interfere with study results; e.g. immuno-suppressive agents other than corticosteroids * Active infection requiring IV antibiotics * Acute or chronic renal insufficiency (a glomerular filtration rate (GFR) \<30 mL/min/1.73m2) or acute renal insufficiency of any severity due to hepato-renal syndrome or in the peri-operative liver transplantation period * Inability, in the opinion of the study investigator, to comply with study and/or follow-up procedures * Current, recent (within 4 weeks of the first infusion of this study), or planned participation in an experimental drug study other than a Genentech-sponsored Avastin cancer study * Life expectancy of less than 12 weeks * Active malignancy, other than superficial basal cell and superficial squamous (skin) cell, or carcinoma in situ of the cervix within last five years * Inadequately controlled hypertension (defined as systolic blood pressure \>150 and/or diastolic blood pressure \> 100 mmHg) * Prior history of hypertensive crisis or hypertensive encephalopathy * New York Heart Association (NYHA) Grade II or greater congestive heart failure * History of myocardial infarction or unstable angina within 6 months prior to Day 1 * History of stroke or transient ischemic attack within 6 months prior to Day 1 * Significant vascular disease (e.g., aortic aneurysm, requiring surgical repair or recent peripheral arterial thrombosis) within 6 months prior to Day 1 * History of hemoptysis (\> or = 1/2 teaspoon of bright red blood per episode) within 1 month prior to Day 1 * Evidence of bleeding diathesis or significant coagulopathy (in the absence of therapeutic anticoagulation) * Major surgical procedure, open biopsy, or significant traumatic injury within 28 days prior to Day 1 or anticipation of need for major surgical procedure during the course of the study * Core biopsy or other minor surgical procedure, excluding placement of a vascular access device, within 7 days prior to Day 1 * History of abdominal fistula, gastrointestinal perforation within 6 months prior to Day 1 * Serious, non-healing wound, active ulcer, or untreated bone fracture * Proteinuria at screening as demonstrated by urinalysis (urine protein) * Known hypersensitivity to any component of Avastin * Pregnancy (positive pregnancy test) or lactation. Use of effective means of contraception (men and women) in subjects of child-bearing potential