Semaxanib is a potent and selective vascular endothelial growth factor (VEGF) receptor protein tyrosine kinase 1/2 inhibitor that also inhibits other tyrosine kinases KIT, MET, FLT3, and RET. Semaxanib inhibited cell migration of human vascular endothelial cells expressing both Flt-1 and KDR in response to VEGF and also inhibited the cell migration in response to placenta growth factor (PIGF), a specific ligand for Flt-1. Chemotaxis of monocytes expressing only Flt-1 was also inhibited by SU5416 in a dose-dependent manner. Semaxanib targets the VEGF pathway, and both in vivo and in vitro studies have demonstrated antiangiogenic potential. On February 2002, Pharmacia, the then-parent of Sugen, prematurely ended Phase III clinical trials of Semaxinib in the treatment of advanced colorectal cancer due to discouraging results.