Receptor tyrosine-protein kinase erbB-2 (ERBB2) (ERBB2)

Receptor tyrosine-protein kinase erbB-2 (ERBB2), also known as HER2, is a key member of the epidermal growth factor receptor family that plays a critical role in regulating cell growth, survival, and differentiation (UniProt: P04626). Unlike its family members, ERBB2 does not bind a specific ligand but instead acts as a preferred dimerization partner for other ErbB receptors, amplifying downstream signaling (NCBI Gene: 2064). The trastuzumab epitope refers to a specific sequence within Domain IV of the ERBB2 extracellular domain where the therapeutic antibody trastuzumab binds (PubMed: 12192405). Overexpression or amplification of ERBB2 is a major driver in several cancers, particularly HER2-positive breast and gastric cancers, where it correlates with increased metastatic potential and poor prognosis (PubMed: 19117931). Targeting this epitope with monoclonal antibodies or antibody-drug conjugates disrupts oncogenic signaling and induces immune-mediated destruction of tumor cells (StatPearls: NBK532259). While highly effective, therapies targeting this receptor require monitoring for potential cardiotoxicity, as ERBB2 also plays a role in cardiac myocyte maintenance (PubMed: 15781630).

Other names

Human epidermal growth factor receptor 2HER2NEUCD340Proto-oncogene NeuMetastatic lymph node gene 19 protein

Trastuzumab and its derivatives bind to the juxtamembrane region (Domain IV) of the ERBB2 extracellular domain, which sterically hinders the formation of HER2-containing heterodimers and inhibits the proteolytic shedding of the extracellular domain (PubMed: 12192405). This binding suppresses downstream oncogenic signaling via the PI3K/Akt and MAPK pathways, leading to cell cycle arrest in the G1 phase (DrugBank: DB00072). Additionally, the Fc portion of these antibodies facilitates antibody-dependent cellular cytotoxicity (ADCC) by recruiting natural killer cells and other immune effectors to the tumor site (PubMed: 21372202).