Ombrabulin hydrochloride is a synthetic, selective CA-4 phosphate ester or derivative of Ombrabulin to disrupt the tubulin cytoskeleton of endothelial cells and has antivascular effects. Ombrabulin is a tubulin polymerizing inhibitor, a member of the combretastatin A-4 compound class, which is a water-soluble tubulin depolymerizing tumor vascularizing compound.