Alanosine in Treating Patients With Progressive or Recurrent Malignant Gliomas

DISEASE CHARACTERISTICS: Histologically confirmed malignant glioma of 1 of the following types: Anaplastic astrocytoma Anaplastic oligodendroglioma Glioblastoma multiforme Progressive or recurrent disease after prior radiotherapy with or without chemotherapy Low-grade glioma that progressed after prior radiotherapy with or without chemotherapy and is found to be high-grade glioma after biopsy allowed No more than 2 prior treatment regimens Measurable disease by CT scan or MRI Documented absence of methylthioadenosine phosphorylase (MTAP) on fixed tumor specimens PATIENT CHARACTERISTICS: Age 18 and over Performance status Karnofsky 60-100% Life expectancy Not specified Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic Bilirubin ≤ 1.5 mg/dL Transaminases ≤ 4 times upper limit of normal Renal Creatinine ≤ 1.5 mg/dL Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective barrier contraception before, during, and for 4 weeks after study participation Mini mental state exam score of ≥ 15 No psychological or sociological condition, addictive disorder, or family problem that would preclude study compliance No other malignancy within the past 5 years except curatively treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix or breast No concurrent serious infection or medical illness that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy No concurrent prophylactic growth factors (e.g., filgrastim [G-CSF] or sargramostim [GM-CSF]) Chemotherapy See Disease Characteristics At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas) Endocrine therapy Must be maintained on a stable or lower corticosteroid regimen from the time of the baseline scan until the start of study treatment No concurrent steroids as antiemetics Radiotherapy See Disease Characteristics At least 3 months since prior radiotherapy Surgery Not specified Other Recovered from prior therapy More than 10 days since prior anticonvulsant drugs that induce hepatic metabolic enzymes No other concurrent investigational agents