DISEASE CHARACTERISTICS:

• Radiographically proven recurrent intracranial malignant glioma, including any of the following subtypes:

  • Glioblastoma multiforme
  • Gliosarcoma
  • Anaplastic astrocytoma
  • Anaplastic oligodendroglioma
  • Anaplastic mixed oligoastrocytoma
  • Malignant astrocytoma not otherwise specified
• Original histological diagnosis of low-grade glioma with subsequent histological diagnosis of malignant glioma allowed

• Must show unequivocal radiographic evidence of tumor progression by MRI or CT scan while on a stable dose of steroids for ≥ 5 days

  • A new baseline MRI or CT scan is required if the steroid dose is increased between the date of imaging and the date of registration

• Must have received prior treatment with ≥ 1 course of standard adjuvant 5-day dose schedule of temozolomide

  • May have had tumor progression while on 5 -day temozolomide schedule or while on another agent
• Failed prior external-beam radiotherapy
• Confirmation of true progressive disease (not radiation necrosis) by PET, thallium scanning, MR spectroscopy, or surgical documentation required if patient received prior interstitial brachytherapy or stereotactic radiosurgery

• Patients having undergone recent resection of recurrent or progressive tumor are eligible provided all of the following conditions apply:

  • Recovered from surgery
  • Residual disease following resection of recurrent intracranial malignant glioma is not mandated for eligibility into the study

PATIENT CHARACTERISTICS:

• Karnofsky performance status 60-100%
• Life expectancy > 8 weeks
• WBC ≥ 3,000/µL
• ANC ≥ 1,500/mm³
• Platelet count ≥ 100,000/mm³
• Hemoglobin ≥ 10 g/dL
• SGOT < 2 times upper limit of normal (ULN)
• Bilirubin < 2 times ULN
• Creatinine < 1.5 mg/dL
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 3 months after discontinuation of study treatment
• No significant medical illness that cannot be adequately controlled with appropriate therapy or would compromise the patient's ability to tolerate this therapy, in the investigator's opinion
• No other cancer except nonmelanoma skin cancer or carcinoma in situ of the cervix unless patient is in complete remission and off all therapy for that disease for at least 3 years
• No active infection or serious intercurrent medical illness
• No other disease that will obscure toxicity or dangerously alter drug metabolism

PRIOR CONCURRENT THERAPY:

• No limitation to the number of prior treatment
• Recovered from prior therapy
• At least 42 days since prior radiotherapy
• At least 28 days since prior cytotoxic therapy (42 days for nitrosoureas)
• At least 28 days since investigational agent
• At least 21 days since prior procarbazine
• At least 14 days since prior vincristine
• At least 7 days since prior noncytotoxic agents (e.g., interferon, tamoxifen, thalidomide, or isotretinoin), except radiosensitizers
• Concurrent neurosurgical management allowed if not for tumor progression
• No prior Gliadel wafers at time of original resection
• No concurrent prophylactic filgrastim (G-CSF)
• No other concurrent investigational agent
• No other concurrent anticancer therapy (i.e., chemotherapy, radiotherapy, hormonal treatment, or immunotherapy)