Preclinical evaluation of sulfatinib, a novel angio-immuno kinase inhibitor targeting VEGFR, FGFR1 and CSF-1R kinases (AACR 2017)
Authors: Jinghong Zhou, Jun Ni, Min Cheng, Na Yang, Junqing Liang, Liang Ge, Wei Zhang, Jianxing Tang, Qiaoling Sun, Fu Li, Jia Hu, Dongxia Shi, Hongbo Chen, Jingwen Long, Junen Sun, Fang Yin, Xuelei Ge, Hong Jia, Feng Zhou, Yongxin Ren, Weiguo Qing and Weiguo Su
Both VEGFR and FGFR signaling pathways can mediate tumor angiogenesis. CSF-1R plays an important role on functions of macrophages. Recently, the roles in increasing tumor immune evasion of VEGFR, FGFR in regulation of T cells, tumor-associated macrophages (“TAMs”) and myeloid-derived suppressor cells have been demonstrated. Therefore, blockade of tumor angiogenesis and tumor immune evasion by simultaneously targeting VEGFR, FGFR and CSF-1R kinases may represent a promising approach for anti-cancer therapy.
We report here the preclinical studies for sulfatinib (HMPL-012), a potent and highly selective small molecule tyrosine kinase inhibitor against VEGFR, FGFR1 and CSF-1R. Sulfatinib inhibited VEGFR1, 2, and 3, FGFR1 and CSF-1R kinases with IC50s in a range of 1~24 nM, and it strongly blocked VEGF induced VEGFR2 phosphorylation in HEK293KDR cells and colony-stimulating factor-1 stimulated CSF-1R phosphorylation in RAW264.7 cells with IC50 of 2 and 79 nM, respectively. Sulfatinib also attenuated VEGF or FGF stimulated HUVEC cells proliferation with IC50 < 50 nM. In animal studies, a single oral dosing of sulfatinib inhibited VEGF stimulated VEGFR2 phosphorylation in lung tissues of nude mice in an exposure-dependent manner. Furthermore, elevation of FGF23 levels in plasma 24 hours post dosing suggested suppression of FGFR signaling. Sulfatinib demonstrated potent tumor growth inhibition in multiple human xenograft models and decreased CD31 expression remarkably, suggesting strong inhibition on angiogenesis through VEGFR and FGFR signaling. In a syngeneic murine colon cancer model CT-26, sulfatinib demonstrated moderate tumor growth inhibition after single agent treatment. Flow cytometry and immunohistochemistry analysis revealed an increase of CD8+ T cells and a significant reduction in TAMs, (CD163+ or F4/80+CD11b+CD45+) and CSF-1R+ TAMs in tumor tissue indicating strong effect on CSF-1R. Interestingly, combination of sulfatinib with a PD-L1 antibody resulted in enhanced anti-tumor effect. These results suggested that sulfatinib has a strong effect in modulating angiogenesis and cancer immunity.
In summary, sulfatinib is a novel angio-immuno kinase inhibitor targeting VEGFR, FGFR1 and CSF-1R kinases that could simultaneously block tumor angiogenesis and immune evasion. This unique feature seems to support sulfatinib as an attractive candidate for exploration of possible combinations with checkpoint inhibitors against various cancers. Sulfatinib is currently in multiple clinical trials including two Phase III trials against neuroendocrine tumors.