Paclitaxel (Taxol) and docetaxel (Taxotere): active chemotherapeutic agents in lung cancer.
Paclitaxel (Taxol), the prototype of a new class of plant-derived antineoplastic compounds, is a natural product isolated from the Pacific yew. Docetaxel (Taxotere) is a hemisynthetic product derived from the European yew. These agents share a unique mechanism of cytotoxic action by promoting assembly of microtubules and rendering the microtubules resistant to depolymerization. In vitro studies suggest a possible role for radiation sensitization. In Phase I trials, the dose-limiting toxicity was neutropenia for both agents. Other toxicities include infusion-related hypersensitivity reactions, alopecia, neurotoxicity, mucositis, diarrhoea and myalgias. To prevent infusion-related reactions, routine premedication is recommended. Noncumulative cardiac toxicity has been observed with paclitaxel. Fluid retention and rash have been reported with docetaxel. In Phase II studies of paclitaxel in advanced non-small cell lung cancer, response rates of 21% and 24% were observed. In Phase II studies of docetaxel in similar patients, response rates ranging from 28-38% were reported, including patients previously treated with cisplatin. The most common toxicity in these studies was neutropenia. Combination studies with cisplatin and other agents are in progress. Paclitaxel and docetaxel are among the most active chemotherapeutic agents for non-small cell lung cancer patients. Their testing will dominate trials of new therapies in this disease for years to come.