Irinotecan Plus Temozolomide in Treating Patients With Recurrent Primary Malignant Glioma

DISEASE CHARACTERISTICS: * Histologically confirmed recurrent primary malignant glioma * Anaplastic astrocytoma * Glioblastoma multiforme * Anaplastic oligodendroglioma * Gliosarcoma * Anaplastic mixed oligoastrocytoma * Measurable disease by MRI or CT * No immediate radiotherapy required * Neurologically stable for at least 2 weeks prior to study PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * Karnofsky 60-100% Life expectancy: * Greater than 12 weeks Hematopoietic: * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Hemoglobin at least 10 g/dL Hepatic: * Bilirubin less than 1.5 times upper limit of normal (ULN) * SGOT and SGPT less than 2.5 times ULN * Alkaline phosphatase less than 2 times ULN Renal: * Blood urea nitrogen and creatinine less than 1.5 times ULN Other: * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * HIV negative * No other nonmalignant systemic disease * No acute infection treated with IV antibiotics * No frequent vomiting or other condition that would preclude oral medication administration (e.g., partial bowel obstruction) * No other prior malignancies except surgically cured carcinoma in situ of the cervix or basal or squamous cell skin cancer PRIOR CONCURRENT THERAPY: Biologic therapy: * No more than 1 prior biologic therapy regimen Chemotherapy: * No more than 1 prior chemotherapy regimen * At least 6 weeks since prior chemotherapy, unless evidence of disease progression * No prior failure of irinotecan or temozolomide Endocrine therapy: * Concurrent corticosteroids allowed Radiotherapy: * See Disease Characteristics * At least 6 weeks since prior radiotherapy, unless evidence of disease progression Surgery: * At least 3 weeks since prior surgery, unless evidence of disease progression, and recovered Other: * No concurrent immunosuppressive agents