O(6)-Benzylguanine in Treating Patients With Malignant Glioma

DISEASE CHARACTERISTICS: Must be undergoing a diagnostic/therapeutic craniotomy for biopsy/resection of recurrent or newly diagnosed (or presumed) cerebral anaplastic astrocytoma or glioblastoma multiforme Patients undergoing stereotactic biopsy or partial resection are eligible PATIENT CHARACTERISTICS: Age: 18 and over Performance status: SWOG 0-2 OR Karnofsky 60-100% Hematopoietic: WBC at least 3,500/mm3 Absolute neutrophil count at least 1,800/mm3 Platelet count at least 125,000/mm3 Hemoglobin at least 9 g/dL Hepatic: Bilirubin less than 1.5 mg/dL SGOT less than 2 times upper limit of normal Renal: Creatinine less than 1.5 mg/dL OR Creatinine clearance greater than 70 mL/min Cardiovascular: No cardiovascular illnesses that cannot be adequately controlled with appropriate therapy or would increase risk, e.g.: Severe cardiac disease such as uncontrolled arrhythmias or conduction defects Major problems with edema (e.g., residual leg swelling from deep venous thrombosis) Recent coronary artery disease Poorly controlled hypertension (systolic pressure greater than 180 mm Hg, diastolic pressure greater than 110 mm Hg) Other: No other medical illnesses that cannot be adequately controlled with appropriate therapy or would increase risk, e.g.: Major problems with edema (e.g., Cushing's syndrome) Major psychiatric illness No other malignancy requiring active therapy Not pregnant or nursing Fertile patients must us effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Must have failed or received no prior treatment with a nitrosourea, procarbazine, or temozolomide No prior O6-benzylguanine At least 4 weeks since prior chemotherapy and recovered Endocrine therapy: Not specified Radiotherapy: At least 6 weeks since prior radiotherapy No prior radiotherapy to greater than 10-20% of bone marrow Other: No concurrent therapy for any other malignancy At least 2 weeks since other prior investigational drug