Ixabepilone (also known as azaepothilone B, or BMS-247550) is an orally bioavailable microtubule inhibitor. Ixabepilone was a semisynthetic analogue of epothilone B with antineoplastic activity. Ixabepilone binds to tubulin and promotes tubulin polymerization and microtubule stabilization, thereby arresting cells in the G2-M phase of the cell cycle and inducing tumor cell apoptosis. This agent demonstrates antineoplastic activity against taxane-resistant cell lines. Ixabepilone was approved in 2007.