Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed glioblastoma multiforme (GBM), including the following:

- Small or large cell GBM

- Gliosarcoma

- Temozolomide-resistant disease, as defined by the following:

- Unequivocal evidence of tumor progression after receiving adjuvant temozolomide
therapy for 5 consecutive days every 28 days for ≥ 2 courses

- Must have failed prior radiotherapy

- Progression must be documented by MRI (while on a stable steroid dose for ≥ 5
days) ≥ 12 weeks after completion of radiotherapy

- Must have paraffin-embedded tissue blocks or ≥ 4 unstained paraffin-embedded
microscope slides available from diagnosis

PATIENT CHARACTERISTICS:

- Karnofsky performance status 60-100%

- Life expectancy > 8 weeks

- WBC ≥ 3,000/mm³

- Absolute neutrophil count ≥ 1,500/mm³

- Platelet count ≥ 100,000/mm³

- Hemoglobin ≥ 10 g/dL (transfusion allowed)

- AST < 2 times upper limit of normal (ULN)

- Bilirubin < 2 times ULN

- Creatinine < 1.5 mg/dL OR creatinine clearance ≥ 60 mL/min

- No significant medical illness that, in the opinion of the investigator, would
preclude study compliance

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No significant active cardiac, hepatic, renal, or psychiatric disease

- No other known active malignancy except for nonmelanoma skin cancer or carcinoma in
situ of the cervix

- No active infection requiring IV antibiotics

- No disease that would obscure toxicity or alter drug metabolism

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- Recovered from prior temozolomide

- Prior resection of recurrent or progressive tumor allowed if all the following
criteria are met:

- Recovered from prior surgery

- Residual disease after resection of recurrent tumor by CT scan or MRI (while on
a stable steroid dose for ≥ 5 days) ≤ 96 hours OR ≥ 4 weeks after surgery

- At least 12 weeks since prior radiotherapy

- No other prior therapy (i.e., polifeprosan 20 with carmustine implant [Gliadel
wafers] or nitrosoureas)

- No other concurrent chemotherapy, radiotherapy, immunotherapy, or investigational
agents