PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy and recovered Chemotherapy: Prior chemotherapy, including fluorouracil and cisplatin, allowed At least 4 weeks since prior chemotherapy (6 weeks for mitomycin and nitrosoureas) and recovered Endocrine therapy: Not specified Radiotherapy: At least 4 weeks since prior radiotherapy and recovered Surgery: Recovered from prior surgery Other: At least 30 days since other prior investigational drugs No other concurrent investigational or commercial agents or therapies No concurrent antiretroviral therapy (HAART)