Conversion of a murine monoclonal antibody A13 targeting epidermal growth factor receptor to a human monoclonal antibody by guided selection

Ki-Hwan Chang,Se-Ho Kim,Gwang-Won Hong,Min-Soo Kim,Yong-Nam Shin

doi:10.3858/emm.2012.44.1.005

Abstract

Epidermal growth factor receptor (EGFR) is an attractive target for tumor therapy because it is overexpressed in the majority of solid tumors and the increase in receptor expression levels has been linked with a poor clinical prognosis. Also it is well established that blocking the interaction of EGFR and the growth factors could lead to the arrest of tumor growth and possibly result in tumor cell death. A13 is a murine monoclonal antibody (mAb) that specifically binds to various sets of EGFR-expressing tumor cells and inhibits EGF-induced EGFR phosphorylation. We isolated human immunoglobulin genes by guided selection based on the mAb A13. Four different human single chain Fvs (scFvs) were isolated from from hybrid scFv libraries containing a human VH repertoire with the VL of mAb A13 and a human VL repertoire with the VH of mAb A13. All the 4 scFvs bound to EGFR-expressing A431 cells. One scFv (SC414) with the highest affinity was converted to IgG1 (ER414). The ER414 exhibited ∼17 fold lower affinity compared to the A13 mAb. In addition the ER414 inhibited an EGF-induced tyrosine phosphorylation of EGFR with much lower efficacy compared to the A13 mAb and Cetuximab (Merck KgaA, Germany). We identified that the epitope of A13 mAb is retained in ER414. This approach will provide an efficient way of converting a murine mAb to a human mAb.

Highlights

Epidermal growth factor receptor (EGFR) is a 170 kDa membrane-spanning glycoprotein comprising an extracellular ligand-binding domain, a transmembrane domain, and an intracellular cytoplasmic protein domain with tyrosine kinase activity (Carpenter, 1987)
EGFR belongs to the human epidermal receptor (HER) family of receptor tyrosine kinases, which consists of four closely related receptors - EGFR (HER1, erbB1), HER2, HER3, and HER4 - that mediate cellular signaling pathways involved in growth and proliferation in response to the binding of a variety of growth factor ligands (Yarden and Sliwkowski, 2001; Laskin and Sandler, 2004)
Monoclonal antibodies directed against the extracellular domain of EGFR and small-molecule compounds that interfere with intracellular EGFR tyrosine kinase activity are major molecules for therapeutics (Herbst, 2004)

Summary

Introduction

Epidermal growth factor receptor (EGFR) is a 170 kDa membrane-spanning glycoprotein comprising an extracellular ligand-binding domain, a transmembrane domain, and an intracellular cytoplasmic protein domain with tyrosine kinase activity (Carpenter, 1987). EGFR belongs to the human epidermal receptor (HER) family of receptor tyrosine kinases, which consists of four closely related receptors - EGFR (HER1, erbB1), HER2 (neu, erbB2), HER3 (erbB3), and HER4 (erbB4) - that mediate cellular signaling pathways involved in growth and proliferation in response to the binding of a variety of growth factor ligands (Yarden and Sliwkowski, 2001; Laskin and Sandler, 2004). The clear potential for EGFR-targeted therapies in the treatment of cancer has prompted the development of a variety of agents targeted to the extracellular ligand-binding domain, the intracellular tyrosine kinase domain, the ligand, or to synthesis of the EGFR (Baselga, 2002; Thomas and Grandis, 2004). Monoclonal antibodies (mAbs) directed against the extracellular domain of EGFR and small-molecule compounds that interfere with intracellular EGFR tyrosine kinase activity are major molecules for therapeutics (Herbst, 2004)

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Conclusion