DISEASE CHARACTERISTICS:

• Histologically proven supratentorial malignant primary glioma, including:

  • Glioblastoma multiforme
  • Anaplastic astrocytoma
  • Anaplastic oligodendroglioma
  • Anaplastic mixed oligoastrocytoma
  • Malignant astrocytoma not otherwise specified
  • Benign or malignant meningiomas, including brain and spinal meningiomas
• Patients with meningiomas are excluded from phase II portion of study
• Must have shown unequivocal evidence of tumor recurrence or progression by CT scan or MRI
• Must have failed prior radiotherapy

• Must have prestudy contrast MRI or contrast CT scan of brain on stable steroid dose within the past 14 days

  • Must be on stable (unchanged) dose of steroids for at least 5 days before scans

• Phase II:

  • Must have completed radiotherapy at least 2 months prior to enrollment

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Karnofsky 60-100%

Life expectancy:

• More than 8 weeks

Hematopoietic:

• WBC at least 2,300/mm^3
• Platelet count at least 100,000/mm^3
• Hemoglobin at least 8 g/dL (transfusion allowed)

Hepatic:

• SGOT less than 2.5 times upper limit of normal
• Bilirubin normal
• No significant active hepatic disease

Renal:

• Creatinine less than 1.5 mg/dL OR
• Creatinine clearance at least 60 mL/min
• No significant active renal disease

Cardiovascular:

• No uncompensated coronary artery disease on ECG or physical examination
• No history of myocardial infarction or severe/unstable angina within the past 6 months
• No deep venous or arterial thrombosis within the past 3 months

Pulmonary:

• No pulmonary embolism within the past 3 months

Other:

• Not pregnant or nursing
• Fertile patients must use effective contraception during and for 2 months after study
• No other serious concurrent illness
• No significant active psychiatric disease
• No diabetes mellitus with severe peripheral vascular disease
• No other malignancy within the past 3 years except nonmelanoma skin cancer or carcinoma in situ of the cervix
• No serious active infection
• No other concurrent disease that would obscure toxic effects or dangerously alter drug metabolism

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 3 weeks since prior biologic therapy (e.g., interferon) and recovered
• No concurrent immunotherapy

Chemotherapy:

• Phase I:

  • No more than 2 prior chemotherapy regimens for recurrent disease

• Phase II:

  • No more than 1 prior chemotherapy regimen for recurrent disease
• At least 2 weeks since prior vincristine
• At least 6 weeks since prior nitrosoureas
• At least 3 weeks since prior procarbazine
• Recovered from prior chemotherapy
• No concurrent chemotherapy

Endocrine therapy:

• See Disease Characteristics
• At least 3 weeks since prior endocrine therapy (e.g., tamoxifen) and recovered

Radiotherapy:

• See Disease Characteristics
• No concurrent radiotherapy

Surgery:

• Recovered from prior surgery
• Recent prior resection of recurrent or progressive tumor allowed

Other:

• No other concurrent investigational agents