A fully human monoclonal antibody to the insulin-like growth factor I receptor blocks ligand-dependent signaling and inhibits human tumor growth in vivo.

Abstract

The insulin-like growth factor I receptor (IGF-IR) is overexpressed in many diverse tumor types and is a critical signaling molecule for tumor cell proliferation and survival. Therapeutic strategies targeting the IGF-IR may therefore be effective broad-spectrum anticancer agents. Through screening of a Fab phage display library, we have generated a fully human antibody (A12) that binds to the IGF-IR with high affinity (4.11 x 10(-11) M) and inhibits ligand binding with an IC(50) of 0.6-1 nM. Antibody-mediated blockade of ligand binding to the IGF-IR inhibited downstream signaling of the two major insulin-like growth factor (IGF) pathways, mitogen-activated protein kinase and phosphatidylinositol 3'-kinase/Akt, in MCF7 human breast cancer cells. As a result, the mitogenic and proliferative potential of IGF-I and IGF-II were significantly reduced. A12 did not block insulin binding to the insulin receptor but could block binding to atypical IGF-IR in MCF7 cells. In addition, A12 was shown to induce IGF-IR internalization and degradation on specific binding to tumor cells, resulting in a significant reduction in cell surface receptor density. In xenograft tumor models in vivo, IGF-IR blockade by A12 was shown to occur rapidly, resulting in significant growth inhibition of breast, renal, and pancreatic tumors. Histological analysis of tumor sections demonstrated a marked increase in apoptotic tumor cells in antibody-treated animals. These results demonstrate that A12 possesses strong antitumor activity in vitro and in vivo and may therefore be an effective therapeutic candidate for the treatment of cancers that are dependent on IGF-IR signaling for growth and survival.

• Authors: Douglas Burtrum, Zhenping Zhu, Dan Lu, Donna Marie Anderson, Marie Prewett, Daniel S Pereira, Rajiv Bassi, Rashed Abdullah, Andrea T Hooper, Henry Koo, Xenia Jimenez, Danielle Johnson, Robin Apblett, Paul Kussie, Peter Bohlen, Larry Witte, Daniel J Hicklin, Dale L Ludwig
• Journal: Cancer research (Cancer Res) Vol. 63 Issue 24 Pg. 8912-21 (Dec 15 2003) ISSN: 0008-5472 [Print] United States
• PMID: 14695208 (Publication Type: Journal Article)

Chemical References

• Antibodies, Monoclonal
• Ligands
• Peptide Library
• Recombinant Proteins
• Insulin-Like Growth Factor I
• Receptor, IGF Type 1

Topics

• Animals
• Antibodies, Monoclonal (pharmacology)
• Antibody Specificity
• Breast Neoplasms (therapy)
• Cell Division (drug effects)
• Female
• Humans
• Insulin-Like Growth Factor I (antagonists & inhibitors, metabolism)
• Ligands
• Mice
• Mice, Nude
• Peptide Library
• Phosphorylation
• Receptor, IGF Type 1 (antagonists & inhibitors, immunology, metabolism)
• Recombinant Proteins (pharmacology)
• Signal Transduction (drug effects)
• Xenograft Model Antitumor Assays