Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of any of the following malignant gliomas:

- Glioblastoma multiforme

- Anaplastic astrocytoma

- Grade 3 or greater WHO astrocytic, oligodendroglial, or mixed glial tumors that
were initially diagnosed by histologic examination of a tumor specimen obtained
from biopsy or resection

- Recurrent disease

- No more than 3 prior recurrences

- Measurable recurrent or residual primary CNS neoplasm on contrast-enhanced MRI or CT
scan

- No evidence of CNS hemorrhage on baseline MRI or CT scan

PATIENT CHARACTERISTICS:

- Karnofsky performance status 60-100%

- Hematocrit > 29%

- Absolute neutrophil count > 1,500/mm³

- Platelet count > 125,000/mm³

- Creatinine < 1.5 mg/dL

- SGOT < 1.5 times upper limit of normal (ULN)

- Bilirubin < 1.5 times ULN

- Not pregnant or nursing

- Fertile patients must use effective contraception

- No active infection

- No significant traumatic injury within the past 28 days

PRIOR CONCURRENT THERAPY:

- At least 6 weeks since prior surgical resection

- More than 28 days since prior major surgical procedure or open biopsy

- More than 7 days since prior minor surgical procedure, fine-needle aspirations, or
core biopsies

- At least 6 weeks since prior chemotherapy*

- At least 4 weeks since prior radiotherapy*

- No concurrent immunosuppressive agents

- No concurrent therapeutic anticoagulation

- Concurrent corticosteroids allowed if dose has been stable for 1 week prior to study
entry NOTE: * Unless there is unequivocal evidence of progressive disease