Current State of the Art of New Tubulin Inhibitors in the Clinic

For years the microtubule stabilizing agents docetaxel and paclitaxel belong to the most successful clinical chemotherapeutic agents. Several attempts have been made over the years to equal and better these drugs. Both taxanes are associated with the notorious side effect neurotoxicity and are often accompanied with increased drug resistance and cross resistance with other chemotherapeutic agents. In addition their high lipophilicity demands use of co-solvents, which are associated with less favorable side effects such as hypersensitivity. To prevent these disadvantages and improve the clinical application of the taxanes several new agents have entered clinical testing. The agents that are discussed are the drug class of the discodermolides; XAA296A and the epothilones; BMS-247550, BMS-310705, epo906, kos-862 and the agents ABT-751 and D-24851. Here we present an overview of recently performed clinical studies to determine the current state of the art of the tubulin inhibitors which are intended to enlarge and improve the clinical use of the taxanes docetaxel and paclitaxel.