definiens: means a small - molecule receptor tyrosine kinase inhibitor that binds to and inhibits signaling ofVEGFRl, VEGFR2, or VEGFR3 . An RTKI may, but need not, bind to and inhibit receptor tyrosine kinases in addition to a VEGFR, such as PDGFRa, PDGFRb, RET and c - Met . Likewise, an RTKI may, but need not, inhibit a different class ofkinases that are not cell surface receptors, such as the serine kinases B - raf and c - raf kinase . Each of the following compounds is a non - limiting example of an RTKI : sorafenib, pazopanib, axitinib, tivozanib, sunitinib, vandetanib, motesanib, vatalanib and samaxanib