DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed glioblastoma multiforme

  • Recurrent disease by CT scan or MRI
  • No prior chemotherapy OR
  • No more than 1 prior chemotherapy regimen in adjuvant setting or for recurrent disease OR

• Histologically or cytologically confirmed anaplastic oligodendroglioma, mixed oligoastrocytoma, anaplastic astrocytoma, or recurrent low-grade astrocytoma

  • Failed prior radiotherapy

  • No more than 1 prior chemotherapy regimen

    • Failed adjuvant chemotherapy OR
    • Failed first-line chemotherapy

• At least 1 bidimensionally measurable target lesion

  • At least 2 cm on contrast-enhanced CT scan or MRI

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• Not specified

Hematopoietic:

• Neutrophil count at least 2,000/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• AST and ALT no greater than 2.5 times ULN
• Alkaline phosphatase no greater than 2.5 times ULN

Renal:

• Creatinine less than 1.7 mg/dL

Cardiovascular:

• Cardiac function normal
• No ischemic heart disease within the past 6 months
• Normal 12-lead ECG

Other:

• No other prior or concurrent malignancy except cone-biopsied carcinoma of the cervix or adequately treated basal cell or squamous cell skin cancer
• No unstable systemic disease
• No active uncontrolled infection
• No psychological, familial, sociological, or geographical condition that would preclude study compliance
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 3 months after study

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No concurrent anticancer biologic agents
• No concurrent cytokines (e.g., filgrastim [G-CSF] or sargramostim [GM-CSF])

Chemotherapy:

• See Disease Characteristics
• At least 4 weeks since prior chemotherapy (6 weeks for nitrosourea)
• No concurrent chemotherapy

Endocrine therapy:

• Must be on stable or decreasing dose of corticosteroids for at least 2 weeks

Radiotherapy:

• See Disease Characteristics
• At least 3 months since prior brain irradiation
• No prior high-dose radiotherapy (more than 65 Gy), stereotactic radiosurgery, or internal radiotherapy unless the recurrence is histologically confirmed
• No concurrent radiotherapy

Surgery:

• Prior surgery for primary brain tumor within the past 3 months allowed provided one of the following conditions are present:

  • Postoperative imaging within 72 hours after surgery shows a clearly limited target lesion of at least 2 cm
  • Postoperative follow-up shows a progressive and measurable target lesion
  • A second measurable target lesion is present outside the surgical area

Other:

• No concurrent warfarin or other anticoagulants
• No other concurrent anticancer agents
• No other concurrent investigational agents