PRIOR CONCURRENT THERAPY: Biologic therapy: At least 8 weeks since prior interleukin-2 and recovered No other prior biologic therapy Chemotherapy: At least 4 weeks since prior chemotherapy and recovered No more than 1 prior chemotherapy regimen Endocrine therapy: Not specified Radiotherapy: At least 4 weeks since prior radiotherapy No concurrent radiotherapy to measurable lesions Surgery: See Disease Characteristics More than 3 weeks since prior major surgery