PANITUMUMAB IS A RECOMBINANT, HUMAN IGG2 KAPPA MONOCLONAL ANTIBODY THAT BINDS SPECIFICALLY TO THE HUMAN EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR). PANITUMUMAB BINDS SPECIFICALLY TO EGFR ON BOTH NORMAL AND TUMOR CELLS, AND COMPETITIVELY INHIBITS THE BINDING OF LIGANDS FOR EGFR. NONCLINICAL STUDIES SHOW THAT BINDING OF PANITUMUMAB TO THE EGFR PREVENTS LIGAND-INDUCED RECEPTOR AUTOPHOSPHORYLATION AND ACTIVATION OF RECEPTOR-ASSOCIATED KINASES, RESULTING IN INHIBITION OF CELL GROWTH, INDUCTION OF APOPTOSIS, DECREASED PROINFLAMMATORY CYTOKINE AND VASCULAR GROWTH FACTOR PRODUCTION, AND INTERNALIZATION OF THE EGFR. IN VITRO ASSAYS AND IN VIVO ANIMAL STUDIES DEMONSTRATE THAT PANITUMUMAB INHIBITS THE GROWTH AND SURVIVAL OF SELECTED HUMAN TUMOR CELL LINES EXPRESSING EGFR.