Panitumumab is the human monoclonal antibody against epidermal growth factor receptor (EGFR). The EGFR is a member of a subfamily of type I receptor tyrosine kinases，including EGFR (HERl，c-ErbB-l)，HER2/neu，HER3，and HER4. EGFR is a transmembrane glycoprotein that is constitutively expressed in many normal epithelial tissues，including the skin and hair follicle. Overexpression of EGFR is also detected in many human cancers，including those of the colon and rectum. Panitumumab binds specifically and selectively to the EGFR，preventing binding of activating ligands，such as the EGF and transforming growth factor-. This binding results in blockade of the essential downstream signaling pathways that are known to govern apoptosis，proliferation and differentiation of both normal and neoplastic cell types in a wide array of tissues.
