DISEASE CHARACTERISTICS:

• Histologically confirmed malignant glioma

  • Anaplastic astrocytoma (AA) OR
  • Glioblastoma multiforme (GBM)
• Recurrent or progressive disease by contrast-enhanced CT scan or MRI after primary surgery and radiotherapy

• At least 1 bidimensionally measurable lesion

  • At least 1 cm by 1 cm on contrast-enhanced CT scan or MRI

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• At least 12 weeks

Hematopoietic:

• Absolute granulocyte count at least 1,500/mm3
• Platelet count at least 120,000/mm3

Hepatic:

• Bilirubin normal
• AST and ALT no greater than 2.5 times upper limit of normal

Renal:

• Creatinine normal OR
• Creatinine clearance at least 60 mL/min

Cardiovascular:

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

Pulmonary:

• DLCO at least 70% of predicted
• FVC at least 70% of predicted

Other:

• No other malignancy within the past 5 years except adequately treated nonmelanoma skin cancer or curatively treated carcinoma in situ of the cervix
• No ongoing or active uncontrolled infection
• No other serious illness or medical condition that would preclude study
• No history of significant neurologic or psychiatric disorder that would preclude study
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for at least 3 months after study

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 6 weeks since prior immunotherapy
• No concurrent immunotherapy

Chemotherapy:

• At least 6 weeks since prior chemotherapy
• No more than 1 prior adjuvant chemotherapy regimen for AA
• No prior chemotherapy for recurrent disease
• No other concurrent chemotherapy

Endocrine therapy:

• Patients must be on a stable dose of steroids for at least 2 weeks prior to study

Radiotherapy:

• See Disease Characteristics
• At least 4 weeks since prior radiotherapy
• No prior radiotherapy for recurrent disease
• No concurrent radiotherapy

Surgery:

• See Disease Characteristics
• Prior surgery for recurrent disease (e.g., stereotactic biopsy or partial resection) allowed
• At least 4 weeks since prior surgery (except for biopsy)

Other:

• At least 6 weeks since prior investigational agents
• No other concurrent investigational agents
• No other concurrent anticancer treatment