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