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