OUTLINE: This is an open label, multicenter study. Patients receive leflunomide (SU101) IV over 6 hours on days 1-4. Patients then receive SU101 IV over 6 hours weekly for 6 weeks (beginning between days 8-12). Patients exhibiting complete response, partial response, or stable disease may continue on treatment for up to a year or until disease progression or unacceptable toxicity occurs. Patients continuing therapy receive SU101 IV over 6 hours every week for 7 weeks, followed by 1 week of rest. Quality of life is assessed every 8 weeks and at the end of the study. Patients are followed every 8 weeks or until tumor progression.