DISEASE CHARACTERISTICS: Histologically confirmed supratentorial glioblastoma multiforme No prior intracranial or intratumoral hemorrhage

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: Greater than 2 months Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 9 g/dL No history of a bleeding disorder that would interfere with protocol therapy Hepatic: Bilirubin no greater than 1.5 mg/dL Transaminases no greater than 4 times upper limit of normal Renal: Creatinine no greater than 1.7 mg/dL Cardiovascular: No suspected disseminated intravascular coagulation No history of venous thrombosis requiring coumadin Other: No serious concurrent infection or other medical illness that would prevent compliance No other malignancy within the past 5 years except curatively treated basal cell skin cancer or carcinoma in situ of the cervix Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior immunotherapy or biologic agents (e.g., immunotoxins, immunoconjugates, antisense, peptide receptor antagonists, interferons, interleukins, lymphokine activated killer cells, tumor infiltrating lymphocytes, or gene therapy) for brain tumor Chemotherapy: No prior chemotherapy for brain tumor Endocrine therapy: No prior hormonal therapy for brain tumor Prior glucocorticoids allowed Maintenance 5 day stable corticosteroid regimen required postsurgery Radiotherapy: No prior radiotherapy for brain tumor Surgery: Prior surgery for brain tumor allowed if recovered from the immediate post operative period