Epothilones and their analogues - a new class of promising microtubule inhibitors

Abstract
Epothilones A and B are naturally occurring microtubule depolymerisation inhibitors, which inhibit the growth of human cancer cells in vitro at nanomolar or even sub-nanomolar concentrations. In contrast to paclitaxel (Taxol®, Bristol-Myers Squibb) epothilones are also active against multi-drug resistant cancer cell lines and epothilone B exhibits potent in vivo antitumour activity against multidrug-resistant tumours. In addition, epothilones A and B have been shown to be active in vitro against cell lines whose paclitaxel-resistance is derived from specific tubulin mutations. Their attractive preclinical profile has made epothilones important lead structures in the search for improved cytotoxic anticancer drugs and hundreds of analogues and derivatives of epothilones have been prepared and biologically characterised over the past four years. While chemical modifications have been reported for almost every position of the epothilone structural framework, the major focus has been on modifications of the ep...