We have previously identified that activation of receptor tyrosine kinases (RTKs), MET and RON contributed to resistance to the EGF receptor (EGFR)-directed therapeutic antibody, cetuximab. These findings originated from our in vitro 3D type I collagen cultures of human colorectal cancer (CRC) cell line HCA-7 derivatives CC, SC, and CC-CR. CC are sensitive to cetuximab, while SC and CC-CR are resistant. Both de novo and acquired modes of cetuximab resistance in SC and CC-CR, respectively, could be overcome by crizotinib, a multi-RTK inhibitor that also targets MET and RON. Conversely, exogenous administration of MET ligand, HGF could transiently induce cetuximab resistance which could be further overcome by crizotinib addition. HGF/HGFL are synthesized as inactive precursors and require cleavage by proteases (HGFA, Matriptase, and Hepsin) to be biologically active. To inhibit HGF/HGFL cleavage in cetuximab-resistant cells, we employed inhibitors of HGF/HGFL proteases (ZFH7116 and VD2173) and were able to overcome both de novo and acquired cetuximab resistance. A survey of TCGA datasets indicated that HGF/HGFL were overexpressed in several CRC CMS subtypes. We next expressed human HGF in cetuximab-sensitive CC cells and observed that HGF overexpression imparts cetuximab resistance. Moreover, cetuximab resistance induced by HGF overexpression could be overcome by the downstream MET inhibition (with crizotinib), and we are now testing if the upstream inhibition of HGF proteases (with ZFH7116/VD2173) also overcomes cetuximab resistance. Combined these results indicate that inhibition of HGF cleavage and maturation may be a novel way to overcome resistance to EGFR-targeted therapies in CRC.

Citation Format: Ramona Graves-Deal, Vivian T. Jones, Galina T. Bogatcheva, Zheng Cao, Sarah J. Harmych, Vishnu Damalanka, Lidija Klampfer, Robert J. Coffey, James W. Janetka, Bhuminder Singh. Inhibition of HGF maturation overcomes cetuximab resistance in colorectal cancer [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr PR010.