Abstract B3: Anti-angiogenic properties of FAK-VEGFR3 scaffold inhibitors, C9 and C10.

Introduction: Focal adhesion kinase (FAK) and vascular endothelial growth factor receptor 3 (VEGFR3) are tyrosine kinases, which function as key modulators of survival and metastasis signals in cancer cells. We have previously shown that VEGFR3 binds to the FAT domain of FAK and this interaction promotes the survival of tumor cells. We developed novel small molecule compounds C9 and C10 which specifically bind and inhibit the FAK-VEGFR3 interaction. Both these compounds inhibit cancer cell proliferation, induce apoptosis, disrupt the FAK-VEGFR3 signaling axis, and significantly inhibit tumor growth in xenograft mouse models of breast and pancreatic cancer. Since FAK and VEGFR3 have been implicated in tumor angiogenesis, we investigated the potential anti-angiogenic effects of C9 and C10. Methods: Binding of C9 and C10 to the FAT domain of FAK was tested using fluorescence polarization. Effects of C9 and C10 were tested in vitro by MTS assay (viability) and tube formation assay using HUVEC cells. Directed in vivo angiogenesis assay (DIVAA) kit was used to determine anti-angiogenic effects of both compounds. Single agent efficacy of C9 and C10 was tested in a pancreatic xenograft mouse model for 30 days. Mouse tumor tissues were analyzed for markers of proliferation (Ki67), endothelial vessels (CD31), and lymphangiogenic vessels (LYVE1) using immunohistochemistry. Results: Fluorescence polarization confirmed that C9 and C10 effectively bind to the FAT domain of FAK. C9 and C10 reduced cell viability of HUVEC cells and dramatically decreased tube formation by reducing total branching points, total loops and total tube length in a dose and time dependent manner. DIVAA assay confirmed that C9 and C10 significantly reduced the formation of endothelial blood vessels as compared to untreated groups. In vivo, 30 days treatment with low doses of C9 and C10 as single agents led to 40% to 45% reduction in tumor volume (P<0.05). Further analyses of these mouse tumors confirmed the anti-angiogenic effects of C9 and C10. Conclusions: We have shown that targeting the FAK-VEGFR3 protein protein interaction site allows for dual inhibition of tumor proliferation as well as tumor angiogenesis. This study highlights the importance of oral-based small molecule inhibitors that might impact the therapeutic management of solid tumors. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B3. Citation Format: Priyanka A. Agharkar, Manivannan Ethirajan, Jianqun Liao, Michael Yemma, Brian Buckley, Mikhail Chernov, William Cance, Ravindra Pandey, Elena Kurenova. Anti-angiogenic properties of FAK-VEGFR3 scaffold inhibitors, C9 and C10. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B3.