Taxoids: a new class of cytotoxic agents

Taxoids (paclitaxel and docetaxel) are a new class of cytotoxic agents. Their mechanism of action (enhanced polymerization of tubulin and inhibition of its depolymerization) acts thereby as mitotic spindle inhibitors. Significant experimental antitumor activity, although more marked with docetaxel, has been observed with both agents. Their main side-effects are reversible non cumulative neutropenia and alopecia; significant hypersensitivity reactions using cortico-steroids antiHT1/2 premedication are seen in < 5% of patients receiving paclitaxel as a pulsed (3 h) infusion; neurotoxicity appears dose-related; docetaxel can induce a peculiar skin toxicity often associated with edema. Paclitaxel at the recommended dose of 175 mg/m2 achieves responses in 20-30% of patients with relapsed ovarian carcinoma; its activity in advanced breast cancer although significant is clearly dose-related with an optimal dose still debatable; responses are observed in approximately 30% of patients with non small cell lung cancer (NSCLC). Docetaxel (100 mg/2) is active in first line treatment of advanced breast cancer (50-72% RR) as well as 2nd line treatment (> 40% RR); an activity in the range of that observed with paclitaxel is reported in NSCLC.