title: Monovalency unleashes the full therapeutic potential of the DN-30 anti-Met antibody.
abstract: Met, the high affinity receptor for hepatocyte growth factor, is one of the most frequently activated tyrosine kinases in human cancer and a validated target for cancer therapy. We previously developed a mouse monoclonal antibody directed against the extracellular portion of Met (DN-30) that induces Met proteolytic cleavage (receptor "shedding") followed by proteasome-mediated receptor degradation. This translates into inhibition of hepatocyte growth factor/Met-mediated biological activities. However, DN-30 binding to Met also results in partial activation of the Met kinase due to antibody-mediated receptor homodimerization. To safely harness the therapeutic potential of DN-30, its shedding activity must be disassociated from its agonistic activity. Here we show that the DN-30 Fab fragment maintains high affinity Met binding, elicits efficient receptor shedding and down-regulation, and does not promote kinase activation. In Met-addicted tumor cell lines, DN-30 Fab displays potent cytostatic and cytotoxic activity in a dose-dependent fashion. DN-30 Fab also inhibits anchorage-independent growth of several tumor cell lines. In mouse tumorigenesis assays using Met-addicted carcinoma cells, intratumor administration of DN-30 Fab or systemic delivery of a chemically stabilized form of the same molecule results in reduction of Met phosphorylation and inhibition of tumor growth. These data provide proof of concept that monovalency unleashes the full therapeutic potential of the DN-30 antibody and point at DN-30 Fab as a promising tool for Met-targeted therapy.
authors.affiliation: Laboratory of Experimental Therapy and Gene Transfer, Institute for Cancer Research and Treatment, Department of Oncological Sciences, University of Turin Medical School, SP 142, km 3.95, I-10060 Candiolo, Turin, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pacchiana
authors.forename: Cristina
authors.initials: C
authors.lastname: Chiriaco
authors.forename: Maria C
authors.initials: MC
authors.lastname: Stella
authors.forename: Fiorella
authors.initials: F
authors.lastname: Petronzelli
authors.forename: Rita
authors.initials: R
authors.lastname: De Santis
authors.forename: Maria
authors.initials: M
authors.lastname: Galluzzo
authors.forename: Paolo
authors.initials: P
authors.lastname: Carminati
authors.forename: Paolo M
authors.initials: PM
authors.lastname: Comoglio
authors.forename: Paolo
authors.initials: P
authors.lastname: Michieli
authors.forename: Elisa
authors.initials: E
authors.lastname: Vigna
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D000915:Antibody Affinity / Q000276:immunology; D017209:Apoptosis / Q000187:drug effects; D001667:Binding, Competitive; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D045325:HCT116 Cells; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D047468:Immunoprecipitation; D051379:Mice; D008819:Mice, Nude; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding; D019859:Proto-Oncogene Proteins c-met / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D019859:Proto-Oncogene Proteins c-met