PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy and recovered No concurrent immunotherapy No concurrent colony stimulating factors (unless evidence of neutropenic infection) Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for nitrosourea or mitomycin) Prior taxanes and vinca alkaloids allowed with recovery (excluding alopecia any grade and peripheral neuropathy no greater than grade 1) No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: At least 4 weeks since prior radiotherapy and recovered At least 6 weeks since prior extensive radiotherapy to greater than 20% of bone marrow No concurrent radiotherapy Surgery: Not specified Other: No other concurrent experimental drugs At least 30 days since other investigational drug