OUTLINE: This is a dose-escalation study. Patients receive leflunomide orally (PO) once daily (QD) on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at 30 days and then every 28 days until disease progression (active follow-up) or every 3 months (long term follow-up).