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.