In vitro activity: Apatinib is a potent, orally bioavailable, and selective inhibitor of the VEGF (vascular endothelial growth factor receptor) signaling pathway with IC50 of 1 nM for VEGFR2. It has potential antiangiogenic and antineoplastic activities. Apatinib potently suppressed the kinase activities of VEGFR-2, c-kit and c-src, and inhibited cellular phosphorylation of VEGFR-2, c-kit and PDGFRβ. Apatinib effectively inhibited proliferation, migration and tube formation of human umbilical vein endothelial cells induced by FBS, and blocked the budding of rat aortic ring. A phase I study of Apatinib has shown encouraging antitumor activity and a manageable toxicity profile. These findings suggest that Apatinib has promise as an antitumor drug and might have clinical benefits. Apatinib effectively inhibits proliferation, migration and tube formation of human umbilical vein endothelial cells induced by FBS, and blocked the budding of rat aortic ring. Apatinib reverses ABCB1- and ABCG2-mediated MDR by inhibiting their transport function, but not by blocking the AKT or ERK1/2 pathway or downregulating ABCB1 or ABCG2 expression. Apatinib significantly potentiates the cytotoxicity of established ABCB1 and ABCG2 substrates and increased the accumulation of DOX and Rho 123 in ABCB1- or ABCG2-overexpressing cells. Furthermore, apatinib significantly inhibited the photoaffinity labeling of both ABCB1 and ABCG2 with [125I]iodoarylazidoprazosin in a concentration-dependent manner.

Kinase Assay: Apatinib (YN968D1) is a novel, orally bioavailable, selective inhibitor with potential antiangiogenic and antineoplastic activities. Apatinib selectively binds to and inhibits VEGFR2. Apatinib can also potently suppress the activities of Ret, c-kit and c-src with IC50 of 0.013 μM, 0.429 μM and 0.53 μM, respectively. Apatinib inhibits cellular phosphorylation of VEGFR-2, c-kit and PDGFRβ. Apatinib significantly inhibits proliferation stimulated by 20 ng/mL VEGF (IC50 = 0.17μM).

Cell Assay: In HUVEC, Apatinib decreases VEGF-stimulated phosphorylation of VEGFR-2 KDR in a concentration-dependent manner. It also completely inhibits VEGFR-2 activation at a concentration of 0.1 μM. Furthermore, Apatinib abrogates the phosphorylation of c-kit and PDGFRb in Mo7e and NIH-3T3 cells stimulated with the relevant ligand, respectively, in a concentration-dependent manner. In addition, Apatinib inhibits proliferation, migration and tube formation of HUVEC in vitro and blocking of rat aortic ring budding.