TY - JOUR
T1 - Enhanced EGFR inhibition and distinct epitope recognition by EGFR antagonistic mAbs C225 and 425
AU - Kamat, Vishal
AU - Donaldson, Joshua M.
AU - Kari, Csaba
AU - Quadros, Marlene R.D.
AU - Lelkes, Peter I.
AU - Chaiken, Irwin
AU - Cocklin, Simon
AU - Williams, John C.
AU - Papazoglou, Elisabeth
AU - Rodeck, Ulrich
PY - 2008/5
Y1 - 2008/5
N2 - Monoclonal antibodies (mAbs) that inhibit activation of the epidermal growth factor receptor (EGFR) have shown therapeutic potential in select malignancies including breast cancer. Here, we describe that combined use of two such mAbs, C225 (Cetuximab) and 425 (EMD55900), reduced growth and survival of EGFR overexpressing MDA-MB-468 breast cancer cells more effectively than either antibody alone. Similarly, the C225/425 antibody combination more effectively inhibited AKT and MAPK phosphorylation in MDA-MB-468 cells. Surface plasmon resonance, size exclusion chromatography and analytical ultracentrifugation demonstrated that mAbs C225 and 425 simultaneously bind to distinct antigenic epitopes on domain III of the soluble wild-type EGFR. Furthermore, neither mAb competed with the other for binding to cells expressing either wild-type EGFR or a mutant EGFR (EGFRvIII) associated with neoplasia. Mutagenesis experiments revealed that residues S460/G461 in EGFR domain III are essential components of the 425 epitope and clearly distinguish it from the EGF/ TGFα binding site and the C225 interaction interface. Collectively, these results support the conclusion that therapeutic EGFR blockade in cancer patients by combined use of mAbs C225 and 425 could provide advantages over the use of the two antibodies as single agents.
AB - Monoclonal antibodies (mAbs) that inhibit activation of the epidermal growth factor receptor (EGFR) have shown therapeutic potential in select malignancies including breast cancer. Here, we describe that combined use of two such mAbs, C225 (Cetuximab) and 425 (EMD55900), reduced growth and survival of EGFR overexpressing MDA-MB-468 breast cancer cells more effectively than either antibody alone. Similarly, the C225/425 antibody combination more effectively inhibited AKT and MAPK phosphorylation in MDA-MB-468 cells. Surface plasmon resonance, size exclusion chromatography and analytical ultracentrifugation demonstrated that mAbs C225 and 425 simultaneously bind to distinct antigenic epitopes on domain III of the soluble wild-type EGFR. Furthermore, neither mAb competed with the other for binding to cells expressing either wild-type EGFR or a mutant EGFR (EGFRvIII) associated with neoplasia. Mutagenesis experiments revealed that residues S460/G461 in EGFR domain III are essential components of the 425 epitope and clearly distinguish it from the EGF/ TGFα binding site and the C225 interaction interface. Collectively, these results support the conclusion that therapeutic EGFR blockade in cancer patients by combined use of mAbs C225 and 425 could provide advantages over the use of the two antibodies as single agents.
KW - Antagonist antibodies
KW - C225
KW - EGFR
KW - Epitope mapping
KW - Synergy
UR - http://www.scopus.com/inward/record.url?scp=45349098002&partnerID=8YFLogxK
UR - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=purepublist2023&SrcAuth=WosAPI&KeyUT=WOS:000257394600018&DestLinkType=FullRecord&DestApp=WOS
U2 - 10.4161/cbt.7.5.6097
DO - 10.4161/cbt.7.5.6097
M3 - Article
C2 - 18424917
SN - 1538-4047
VL - 7
SP - 726
EP - 733
JO - Cancer Biology and Therapy
JF - Cancer Biology and Therapy
IS - 5
ER -