title: Discovery of fully human anti-MET monoclonal antibodies with antitumor activity against colon cancer tumor models in vivo.
abstract: The receptor tyrosine kinase MET is a major component controlling the invasive growth program in embryonic development and in invasive malignancies. The discovery of therapeutic antibodies against MET has been difficult, and antibodies that compete with hepatocyte growth factor (HGF) act as agonists. By applying phage technology and cell-based panning strategies, we discovered two fully human antibodies against MET (R13 and R28), which synergistically inhibit HGF binding to MET and elicit antibody-dependent cellular cytotoxicity. Cell-based phosphorylation assays demonstrate that R13 and R28 abrogate HGF-induced activation of MET, AKT1, ERK1/2, and HGF-induced migration and proliferation. FACS experiments suggest that the inhibitory effect is mediated by "locking" MET receptor in a state with R13, which then increases avidity of R28 for the extracellular domain of MET, thus blocking HGF binding without activating the receptor. In vivo studies demonstrate that the combination of R13/28 significantly inhibited tumor growth in various colon tumor xenograft models. Inhibition of tumor growth was associated with induction of hypoxia. Global gene expression analysis shows that inhibition of HGF/MET pathway significantly upregulated the tumor suppressors KLF6, CEACAM1, and BMP2, the negative regulator of phosphatidylinositol-3-OH-kinase PIK3IP1, and significantly suppressed SCF and SERPINE2, both enhancers of proliferation and invasiveness. Moreover, in an experimental metastasis model, R13/28 increased survival by preventing the recurrence of otherwise lethal lung metastases. Taken together, these results underscore the utility of a dual-antibody approach for targeting MET and possibly other receptor tyrosine kinases. Our approach could be expanded to drug discovery efforts against other cell surface proteins.
authors.affiliation: Department of Cancer Biology, OncoMed Pharmaceuticals Inc., 800 Chesapeake Dr., Redwood City, CA 94063, USA. edward.vanderhorst@oncomed.com
authors.forename: Edward Htun
authors.initials: EH
authors.lastname: van der Horst
authors.forename: Lawrence
authors.initials: L
authors.lastname: Chinn
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Timothy
authors.initials: T
authors.lastname: Velilla
authors.forename: Hoang
authors.initials: H
authors.lastname: Tran
authors.forename: Yarrow
authors.initials: Y
authors.lastname: Madrona
authors.forename: Andrew
authors.initials: A
authors.lastname: Lam
authors.forename: May
authors.initials: M
authors.lastname: Ji
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Hoey
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Sato
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D000918:Antibody Specificity / Q000276:immunology*; D000970:Antineoplastic Agents / Q000276:immunology* / Q000494:pharmacology; D015153:Blotting, Western; D002465:Cell Movement; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000276:immunology*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D017228:Hepatocyte Growth Factor / Q000037:antagonists & inhibitors; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D011518:Proto-Oncogene Proteins / Q000276:immunology*; D019859:Proto-Oncogene Proteins c-met; D017978:Receptors, Growth Factor / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D011518:Proto-Oncogene Proteins; D017978:Receptors, Growth Factor; D017228:Hepatocyte Growth Factor; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met