Vascular Disrupting Agents, or VDAs, are a new type of potential cancer therapy that works by collapsing the blood vessels inside of a tumor and ‘starving' the tumor from within. As VDAs enter the bloodstream, they bind to tubulin, which is a protein found in the cells lining blood vessels. In normal blood vessels, this tubulin-binding has little effect because these vessels also have a well-organized ‘scaffolding' system to keep them intact. In abnormal cells, however, such as those found in tumors or on the retina in some eye diseases, such supports are not present and the VDA causes the cell to become round. As these cells round up, they block the flow of blood to the tumor.