DISEASE CHARACTERISTICS:

• Histologically confirmed malignant glioma (anaplastic astrocytoma, anaplastic oligodendroglioma, or glioblastoma multiforme)

  • Progressive or recurrent disease after prior radiotherapy with or without chemotherapy
  • Low-grade glioma that progressed to high-grade glioma after prior radiotherapy with or without chemotherapy allowed
• Measurable disease by MRI or CT scan

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• Karnofsky 60-100%

Life expectancy

• Not specified

Hematopoietic

• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• No bleeding diathesis

Hepatic

• Bilirubin ≤ 1.5 mg/dL
• Transaminases ≤ 4 times upper limit of normal
• PT/PTT normal
• INR normal

Renal

• Creatinine ≤ 1.7 mg/dL

Cardiovascular

• No uncontrolled hypertension
• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective barrier contraception during and for 8 weeks after study participation
• Mini Mental State exam score ≥ 15
• No serious infection
• No psychiatric illness or social situation that would preclude study compliance
• No other medical illness that would preclude study participation
• No other malignancy within the past 5 years except curatively treated carcinoma in situ or basal cell skin cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No concurrent prophylactic filgrastim (G-CSF)
• No concurrent immunotherapy

Chemotherapy

• See Disease Characteristics
• At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas)
• No concurrent chemotherapy

Endocrine therapy

• Concurrent steroids allowed
• No concurrent hormonal therapy

Radiotherapy

• See Disease Characteristics
• At least 3 months since prior radiotherapy
• No concurrent radiotherapy

Surgery

• No concurrent surgery

Other

• Recovered from all prior therapy
• No enzyme-inducing anticonvulsant drugs for at least 10 days before starting non-enzyme-inducing anticonvulsant drugs
• No more than 1 prior treatment for cancer

• No concurrent therapeutic anticoagulation

  • Concurrent prophylactic anticoagulation (i.e., low-dose warfarin) for venous or arterial access devices allowed
• No other concurrent investigational agents
• No other concurrent anticancer therapy