DISEASE CHARACTERISTICS:

• Diagnosis of 1 of the following:

  • Histologically confirmed high-grade glioma (WHO grade III or IV) at any site within the brain, including the following:

    • Anaplastic astrocytoma
    • Glioblastoma multiforme (including giant cell and gliosarcoma subtypes)
    • Anaplastic oligodendroglioma
    • Anaplastic ganglioglioma
    • Anaplastic oligoastrocytoma

  • Diffuse brain stem glioma

    • Histologic confirmation not required
  • Histologically confirmed medulloblastoma
  • Histologically confirmed ependymoma

  • Primary spinal cord malignant glioma with measurable metastatic disease within the brain

    • Histologic confirmation required
  • Neuraxis dissemination allowed provided there is bidimensionally measurable disease within the brain and spinal cord
  • Low grade glioma at any site within the brain with or without spinal cord disease

• Recurrent, progressive, or refractory disease (must have received prior chemoradiotherapy)

  • No more than 2 prior chemotherapy regimens following relapse

• Bidimensionally measurable disease, defined as ≥ 1 lesion that can be accurately measured in ≥ 2 planes

  • If there is spinal cord disease as well, response assessment will be based only upon the measurable tumor in the brain
• No diffuse gliomatosis cerebri with < 1 discrete, measurable lesion
• No evidence of new symptomatic CNS hemorrhage (> grade 2) within the past 2 weeks
• No central non-cerebellar PNET's (e.g., cerebral PNET or pineoblastoma)
• No spinal cord tumors only

PATIENT CHARACTERISTICS:

• Karnofsky performance status (PS) 50-100% (> 16 years of age) OR Lansky PS 50-100% (≤ 16 years of age)
• Absolute neutrophil count ≥ 1,500/mm³ (unsupported)
• Platelet count ≥ 100,000/mm³ (unsupported)
• Hemoglobin > 8 g/dL (support allowed)
• Creatinine normal
• BUN < 25 mg/dL
• Bilirubin ≤ 1.5 times upper limit of normal (ULN)
• ALT and AST ≤ 3 times ULN
• Neurological deficits must be stable for ≥ 1 week prior to study entry
• No active renal, cardiac (congestive cardiac failure, myocarditis), or pulmonary disease
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for ≥ 6 months after completion of study treatment

• No clinically significant unrelated systemic illness that would preclude study treatment, including any of the following:

  • Serious infections
  • Significant cardiac, pulmonary, hepatic, or other organ dysfunction
• No uncontrolled systemic hypertension, defined as systolic blood pressure (BP) and/or diastolic BP > 95th percentile for age
• No stroke, myocardial infarction, or unstable angina within the past 6 months
• No clinically significant peripheral vascular disease
• No significant traumatic injury within the past 6 weeks
• No evidence of bleeding diathesis, coagulopathy, or PT INR > 1.5
• Urine protein/creatinine ratio ≤ 1.0
• No abdominal fistula or gastrointestinal perforation within the past 6 months
• No serious nonhealing wound, ulcer, or bone fracture

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• At least 3 weeks since prior myelosuppressive anticancer chemotherapy (6 weeks for nitrosoureas)
• At least 7 days since prior investigational or biologic agents (3 weeks if patient experienced ≥ grade 2 myelosuppression or if agent has a prolonged half-life)
• More than 7 days since prior minor surgery
• More than 12 weeks since prior craniospinal or focal irradiation to primary tumor or other sites
• At least 4 weeks since prior major surgery and recovered
• At least 3 months since prior autologous bone marrow or stem cell transplantation
• At least 2 weeks since prior colony-forming growth factors (i.e., filgrastim [G-CSF], sargramostim [GM-CSF], epoetin alfa)
• No prior bevacizumab or irinotecan hydrochloride
• No anticipated surgery during treatment
• No concurrent prophylactic G-CSF, GM-CSF, or epoetin alfa
• No other concurrent anticancer or investigational drugs
• Concurrent dexamethasone allowed provided the dose is stable or decreasing over the past week
• No concurrent medications that may interfere with study (e.g., immunosuppressive agents other than corticosteroids)
• No concurrent therapeutic anticoagulation
• No concurrent nonsteroidal anti-inflammatory drugs, clopidogrel bisulfate, dipyridamole, or acetylsalicylic acid (aspirin) > 81 mg/day