Onartuzumab (MetMAb) is a humanized anti-tyrosine kinase c-MET monovalent monoclonal antibody.Onartuzumab has antitumor activity with inhibitory effects on HGF binding, receptor phosphorylation, and signal transduction.

c-Met:1.8 n M

Onartuzumab acts specifically by blocking the binding of the HGF α-chain (but not β-chain) to MET[1].
With an inhibitory concentration (IC50) of 1.8 nM, Onartuzumab effectively blocks HGF binding to human c-Met. This inhibition results in the prevention of c-Met auto-phosphorylation and subsequent cell proliferation in numerous cancer cell lines[2].

Administered twice a week for two months at a dose of 30 mg/kg via intraperitoneal injection, Onartuzumab suppresses tumor growth[3].