Leflunomide in Treating Patients With Anaplastic Astrocytoma in First Relapse

DISEASE CHARACTERISTICS: Histologically confirmed anaplastic astrocytoma or anaplastic oligoastrocytoma in first relapse Recurrence or progression at least 6 months from initial diagnosis Must have received maximally feasible surgical resection and fractionated external beam radiotherapy Must have received no more than 1 prior systemic cytotoxic chemotherapy regimen for initial disease Bidimensionally measurable disease by MRI scan (stable dose of corticosteroids for at least 7 days prior to scan) PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 75,000/mm3 Hemoglobin at least 9 g/dL Hepatic: AST no greater than 3 times upper limit of normal (ULN) Bilirubin less than 1.5 times ULN Renal: Creatinine no greater than 2 mg/dL OR Creatinine clearance at least 40 mL/min Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 3 months after the study No known allergy to etoposide No other acute or chronic medical illness or psychiatric disorder PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior epoetin alfa, filgrastim (G-CSF), or sargramostim (GM-CSF) and recovered No concurrent immunotherapy Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy (2 weeks since vincristine; 6 weeks since nitrosoureas or mitomycin) and recovered No prior leflunomide (SU101) therapy No other concurrent chemotherapy Endocrine therapy: No concurrent hormonal therapy (except medroxyprogesterone acetate for appetite stimulation) Radiotherapy: See Disease Characteristics No more than 1 prior course of radiotherapy At least 8 weeks since prior radiotherapy and recovered No prior interstitial radiotherapy or implanted carmustine wafers Prior radiosensitizer(s) concurrent with radiotherapy or used as neoadjuvant therapy allowed No concurrent radiotherapy Surgery: See Disease Characteristics No more than 2 prior surgical resections At least 1 week since prior surgery or biopsy for anaplastic astrocytoma No concurrent surgery (including resection, stereotactic surgery, or interstitial implants) Other: At least 4 weeks since prior investigational agents No other concurrent investigational agents