Matuzumab Binding to EGFR Prevents the Conformational Rearrangement Required for Dimerization

• Published in: Cancer cell 2008-04, Vol.13 (4), p.365-373
• Main Authors: Schmiedel, Judith, Blaukat, Andree, Li, Shiqing, Knöchel, Thorsten, Ferguson, Kathryn M.
• Format: Article
• Language: English
• Subjects: Antibodies, Monoclonal - chemistry; Antibodies, Monoclonal - metabolism; Antibodies, Monoclonal - pharmacology; Antibodies, Monoclonal, Humanized; Antineoplastic Agents - chemistry; Antineoplastic Agents - metabolism; Antineoplastic Agents - pharmacology; Binding Sites; Cell Line, Tumor; Cell Membrane - drug effects; Cell Membrane - enzymology; CELLCYCLE; Cetuximab; CHEMBIO; Crystallography, X-Ray; Dimerization; Enzyme Activation - drug effects; Epitopes - chemistry; ErbB Receptors - antagonists & inhibitors; ErbB Receptors - chemistry; ErbB Receptors - metabolism; Humans; Immunoglobulin Fab Fragments - chemistry; Ligands; Models, Molecular; Protein Conformation - drug effects; Protein Structure, Tertiary; PROTEINS; Solubility
• ISSN: 1535-6108; 1878-3686
• DOI: 10.1016/j.ccr.2008.02.019

An increasing number of therapeutic antibodies targeting tumors that express the epidermal growth factor receptor (EGFR) are in clinical use or late stages of clinical development. Here we investigate the molecular basis for inhibition of EGFR activation by the therapeutic antibody matuzumab (EMD72000). We describe the X-ray crystal structure of the Fab fragment of matuzumab (Fab72000) in complex with isolated domain III from the extracellular region of EGFR. Fab72000 interacts with an epitope on EGFR that is distinct from the ligand-binding region on domain III and from the cetuximab/Erbitux epitope. Matuzumab blocks ligand-induced receptor activation indirectly by sterically preventing the domain rearrangement and local conformational changes that must occur for high-affinity ligand binding and receptor dimerization.