KRN633 is a selective inhibitor of Vascular endothelial growth factor receptors VEGFR-1, -2, and -3. KRN633 also blocked the activation of mitogen-activated protein kinases by VEGF, along with human umbilical vein endothelial cell proliferation and tube formation. KRN633 inhibited tumor growth in several in vivo tumor xenograft models with diverse tissue origins, including lung, colon, and prostate, in athymic mice and rats. Kirin Brewery developed angiogenesis inhibitor KRN 633 as a treatment for solid tumours. It is in phase I clinical trials.