O(6)-Benzylguanine and Temozolomide in Treating Patients With Glioblastoma Multiforme That Did Not Respond to Previous Temozolomide and Radiation Therapy

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
* White blood cell (WBC) ≥ 3,000/mm(³)
* Absolute neutrophil count ≥ 1,500/mm(³)
* Platelet count ≥ 100,000/mm(³)
* Hemoglobin ≥ 10 g/dL (transfusion allowed)
* Aspartate aminotransaminase (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 intravenous (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 computed tomography (CT) scan or magnetic resonance imaging (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