NCIt definition : A humanized monoclonal antibody (MoAb) directed against the human receptor tyrosine-protein
kinase ErbB-3 (HER3) with potential antineoplastic activity. Anti-ErbB3 MoAb AV-203
binds to and inhibits both ligand neuregulin-1 (NRG-1)-dependent and ligand-independent
ErbB3 activation, which may result in inhibition of ErbB3-dependent PI3K/Akt signaling
and may lead to inhibition of cellular proliferation and differentiation. ErbB3, a
member of the epidermal growth factor receptor (EGFR) family, is frequently overexpressed
in solid tumors and its overexpression generally correlates with poor prognosis and
tumor resistance; it has no active kinase domain itself but is activated through heterodimerization
with other members of the EGFR receptor family that do.;