PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy and recovered Chemotherapy: At least 4 weeks since prior chemotherapy and recovered Endocrine therapy: At least 4 weeks since prior hormonal antitumor therapy No concurrent steroids or hormonal therapy Radiotherapy: At least 4 weeks since prior radiotherapy and recovered Concurrent radiotherapy allowed Surgery: Greater than 4 weeks since prior surgery except biopsy or fine needle aspiration of tumor masses Other: At least 4 weeks since other prior investigational drugs or therapies No other concurrent anticancer treatments No other concurrent investigational therapy