An orally bioavailable anilinophthalazine with potential antineoplastic activity. Vatalanib binds to and inhibits the protein kinase domain of vascular endothelial growth factor receptors 1 and 2; both receptor tyrosine kinases are involved in angiogenesis. This agent also binds to and inhibits related receptor tyrosine kinases, including platelet-derived growth factor (PDGF) receptor, c-Kit, and c-Fms. OR A substance that is being studied in the treatment of cancer. It belongs to the families of drugs called protein tyrosine kinase inhibitors and VEGF receptor kinase inhibitors. Also called PTK787/ZK 222584.