A vascular-targeting agent (VTA) or vascular disrupting agent (VDA) is a drug designed to damage the vasculature (blood vessels) of cancer tumors causing central necrosis. A vascular-targeting agent (VTA) or vascular disrupting agent (VDA) is a drug designed to damage the vasculature (blood vessels) of cancer tumors causing central necrosis. VTAs can be small-molecule or ligand-based.