RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. It is not yet known whether SU-101 is more effective than procarbazine in treating patients with glioblastoma multiforme.

PURPOSE: Randomized phase III trial to compare the effectiveness of SU-101 with that of procarbazine in treating patients with glioblastoma multiforme that has recurred.

OBJECTIVES: I. Compare the median survival of patients with glioblastoma multiforme in first relapse treated with intravenous leflunomide (SU101) administered as a loading dose with weekly maintenance therapy versus oral, single-agent procarbazine administered daily for 28 days every 56 days. II. Compare the median time to progression for these regimens in these patients. III. Assess the objective response of these patients. IV. Assess the safety of SU101 given on this schedule. V. Describe the health-related quality of life of these patients.

OUTLINE: This is a randomized, open label, multicenter study. Patients are stratified according to performance status (Karnofsky 60-80% vs 90-100%), age (less than 50 vs 50 and over), and time from initial diagnosis to recurrence (6 months or greater vs less than 6 months). Patients are randomized to one of two treatment arms. Arm I: Patients receive leflunomide (SU101) IV over 6 hours daily on days 1-4, again 4-8 days later, and weekly thereafter for a total of 4 loading dose infusions and six maintenance infusions in course 1. Patients receive 7 weekly maintenance infusions of SU101 in courses thereafter. Treatment repeats every 8 weeks. Arm II: Patients receive procarbazine orally once or twice daily for 4 weeks. Treatment is repeated every 8 weeks. All patients complete a health-related quality-of-life questionnaire every 8 weeks and at study withdrawal. Treatment courses continue up to a maximum of 1 year in the absence of unacceptable toxicity or disease progression. Patients are followed every 2 months, beginning 30 days after study completion.

PROJECTED ACCRUAL: A maximum of 380 patients will be accrued for this study.

DISEASE CHARACTERISTICS: Histologically proven refractory or recurrent supratentorial glioblastoma multiforme Bidimensionally measurable, enhancing residual disease by T1-weighted gadolinium-enhanced MRI required within 15 days prior to treatment Stable dose of corticosteroids required 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 without blood transfusions for 15 days prior to treatment Hepatic: AST/SGOT 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 allergic to etoposide Effective contraception required of fertile patients Negative serum pregnancy test required of fertile women No other acute or chronic medical or psychiatric condition

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior leflunomide (SU101) therapy No more than one prior single-agent or combination systemic chemotherapy regimen for initial disease Radiosensitizer(s) concurrent with radiotherapy allowed in addition to chemotherapy for primary disease At least 6 weeks since nitrosourea or mitomycin At least 2 weeks since vincristine No prior single-agent procarbazine At least 4 weeks since other chemotherapy No concurrent chemotherapy agents Endocrine therapy: No concurrent hormone therapy (except medroxyprogesterone acetate for appetite stimulation) Less than 4 weeks of prior hormonal therapy (tamoxifen or retinoids) if failed one prior chemotherapy regimen Radiotherapy: Prior conventional radiotherapy for initial disease required No more than one prior course of radiotherapy At least 8 weeks since radiotherapy No prior interstitial radiotherapy No concurrent radiotherapy Surgery: Maximally feasible resection for initial disease required No more than two resections permitted At least 1 week since surgery and/or biopsy for disease No prior interstitial radiotherapy or implanted BCNU-wafers No concurrent surgery (including resection, stereotactic surgery or interstitial implants) Other: No concurrent investigational agent At least 4 weeks since prior investigational agent At least 1 week since cholestyramine or monoamine oxidase inhibitors