OUTLINE: This is a multicenter study. Patients receive SU5416 IV over 30-60 minutes twice weekly and interferon alfa-2b subcutaneously every 12 hours daily. Treatment continues every 6 weeks for a minimum of 2 courses. Patients who achieve partial response or stable disease after completion of course 2 receive additional courses in the absence of disease progression or unacceptable toxicity. Patients who achieve complete response may receive additional courses, at the discretion of the protocol investigator, in the absence of disease progression or unacceptable toxicity. Patients with disease progression are allowed to stay on the study until any measurable lesion increases to over 100% of baseline measurement. Patients are followed for survival.