Gimatecan in Treating Patients With Recurrent or Progressive Primary Malignant Glioma

DISEASE CHARACTERISTICS: * Histologically confirmed malignant glioma (glioblastoma multiforme, anaplastic astrocytoma, or anaplastic oligodendroglioma) * Recurrent or progressive primary CNS neoplasm by contrast-enhanced MRI * Tumor progression after prior surgery, radiotherapy, or chemotherapy * Measurable or evaluable disease * Failed prior standard curative or palliative therapy (phase I only) PATIENT CHARACTERISTICS: Age * 18 and over Performance status * Karnofsky 60-100% Life expectancy * At least 3 months Hematopoietic * Absolute neutrophil count ≥ 2,000/mm\^3 * Platelet count ≥ 100,000/mm\^3 Hepatic * SGPT and SGOT ≤ 1.5 times upper limit of normal (ULN) (3 times ULN if liver metastases are present) * Alkaline phosphatase ≤ 2.5 times ULN (5 times ULN if liver metastases are present) * Bilirubin normal Renal * Creatinine ≤ 1.5 times ULN Cardiovascular * No myocardial infarction with the past year * No heart failure (including cardiac insufficiency controlled by digitalis and diuretics) * No irreversible arrhythmias requiring permanent medication * No uncontrolled hypertension Gastrointestinal * No gastrointestinal dysfunction that would alter absorption or motility, such as any of the following: * Active peptic ulcer * Inflammatory bowel disease * Known intolerance to lactose * Malabsorption syndromes * Intestinal sub-occlusion Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective barrier contraception * No active infection * No mentally incapacitated patients * No other concurrent severe disease that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy * No concurrent immunotherapy Chemotherapy * See Disease Characteristics * At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas) * No more than 1 prior chemotherapy regimen * No other concurrent chemotherapy Endocrine therapy * Concurrent corticosteroids allowed if dose stable for the past 2 weeks * No concurrent hormonal therapy Radiotherapy * See Disease Characteristics * At least 4 weeks since prior radiotherapy * No concurrent radiotherapy Surgery * See Disease Characteristics * At least 3 weeks since prior surgical resection * No prior gastrointestinal surgery that would affect drug absorption Other * More than 4 weeks since prior participation in any other investigational drug study * More than 72 hours since prior systemic antibiotics * No concurrent H2 antagonists, antacids, or proton pump inhibitors * If any of these therapies are necessary, ≥ 3 hours must elapse after gimatecan administration * No other concurrent anticancer therapy * No other concurrent investigational drugs * No other concurrent immunosuppressive agents