Development of the taxoids has progressed rapidly in the 1990s. In vitro studies have demonstrated that docetaxel (Taxotere) has a longer residence time and higher accumulation within tumor cells than paclitaxel (Taxol), possibly accounting for its greater cytotoxicity. Animal studies have shown docetaxel to possess high antitumor activity. In clinical studies, docetaxel as a single agent has been shown to be highly active against a variety of solid tumors. It is at least as active in metastatic disease as other agents currently used, and it has demonstrated effectiveness against tumors resistant to anthracyclines or paclitaxel. Docetaxel shows some activity in cell lines resistant to fluorouracil (5-FU), vincristine, cisplatin (Platinol), and etoposide (VePesid). Its unique mechanism of action and lack of cross-resistance or overlapping toxicities with many agents may also contribute to its efficacy and safety in combination therapy.