Taxol, Taxotere and other new taxanes

Paclitaxel (Taxol ® ) and docetaxel (Taxotere ® ) are two new antineo-plastic agents which share a novel mechanism of action. Through promotion of microtubular aggregation, these compounds interfere with essential cellular processes including mitosis, motility, transport and maintenance of cellular structure. Both agents possess a broad spectrum of antitumour activity in vitro and in vivo. Although limited supply of paclitaxel slowed its early clinical development, this problem has recently been overcome. Both paclitaxel and docetaxel have significant clinical activity against a variety of solid tumours including ovarian, breast and lung cancers. Toxicity profiles are similar, with both agents associated with dose-limiting myelosuppression. Paclitaxel is more prone to result in cardiac conduction defects and acute hypersensitivity reactions, while docetaxel is more likely to result in dermatitis and extravascular fluid accumulation. Major pharmaceutical efforts currently centre around improving drug extraction, semisynthetic production of the parent compound, enhancement of water solubility and identification of non-cross resistant taxane analogues. Given the impressive clinical activity seen with paclitaxel and docetaxel, the taxanes will remain an important focus for predinical and clinical drug development in oncology.