Thalidomide, Celecoxib, and Combination Chemotherapy in Treating Patients With Relapsed or Refractory Malignant Glioma

DISEASE CHARACTERISTICS: * Histologically confirmed intracranial malignant glioma, including glioblastoma multiforme, gliosarcoma, anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic mixed oligoastrocytoma, or malignant astrocytoma not otherwise specified * Unequivocal evidence of relapsed or refractory disease by MRI or CT scan and/or tumor resection * Steroid therapy prior to MRI or CT scan must have been at a stable dose for at least 5 days * Failed prior radiotherapy * Must have confirmation of true progression rather than radiation necrosis if previously treated with interstitial brachytherapy or stereotactic radiosurgery PATIENT CHARACTERISTICS: Age * 18 and over Performance status * Karnofsky 60-100% Life expectancy * More than 2 months Hematopoietic * Absolute neutrophil count at least 1,500/mm3 * Platelet count at least 100,000/mm3 * Hemoglobin greater than 9 g/dL * No history of bleeding disorder Hepatic * Bilirubin less than 1.5 mg/dL * SGPT less than 2.5 times normal * Alkaline phosphatase less than 2.5 times normal Renal * Creatinine less than 1.5 times upper limit of normal (ULN) OR * BUN less than 1.5 times ULN Cardiovascular * No deep vein thrombosis within the past 3 weeks (must be clinically stable) Pulmonary * No pulmonary embolism within the past 3 weeks (must be clinically stable) Other * No peripheral neuropathy grade 2 or greater * No active infection * No other serious concurrent medical illness * No concurrent illness that may obscure toxicity or dangerously alter drug metabolism * No other malignancy within the past 3 years except nonmelanoma skin cancer or carcinoma in situ of the cervix * Must participate in the System for Thalidomide Education and Prescribing Safety program * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use 2 forms of effective contraception for 1 month before, during, and for 1 month after study PRIOR CONCURRENT THERAPY: Biologic therapy * No prior oral thalidomide or celecoxib for more than 2 months duration Chemotherapy * No prior oral etoposide or cyclophosphamide for more than 2 months duration * Prior standard-dose IV etoposide and cyclophosphamide allowed Endocrine therapy * See Disease Characteristics * Concurrent steroids allowed Radiotherapy * See Disease Characteristics * At least 4 weeks since prior radiotherapy Surgery * See Disease Characteristics * Prior surgery for relapsed or refractory disease allowed * Recovered from prior surgery * No concurrent surgery Other * No other concurrent investigational agents or treatment * No other concurrent anticancer therapy * Concurrent antiseizure medications allowed