Discovery of novel anti-angiogenesis agents. Part 8: Diaryl thiourea bearing 1H-indazole-3-amine as multi-target RTKs inhibitors

VEGFR-2, TIE-2, and EphB4 are essential for both angiogenesis and tumorigenesis. Herein, we designed and prepared three classes of multi-target inhibitors based on the extensive sequence homology along the kinase domain of angiogenic RTKs. Biological evaluation indicated that these multi-target inhibitors exhibited considerable potential as novel anti-angiogeneic and anticancer agents. Among them, a diaryl thiourea bearing 1H-indazole-3-amine (16a) displayed the most potent RTK inhibition and excellent selectivity. It also showed inhibition on viability of human umbilical vein endothelial cells and anti-proliferation against a broad spectrum of cancer cells. Therefore, 1H-indazole-3-amine could serve as a promising hinge binding group for multi-target inhibitors of VEGFR-2, Tie-2, and EphB4.