Onartuzumab (Anti-HGFR / c-Met) is a unique, humanized and affinity-matured monovalent (one-armed) monoclonal antibody against the MET receptor. Onartuzumab potently inhibits HGF binding and receptor phosphorylation and signaling. Onartuzumab has antibody-like pharmacokinetics and antitumor activity. MW: 144.64 KD.