ErbB Receptors and ErbB Targeted Therapies in Endometrial Cancer

Abstract

The Epidermal Growth Factor system is present in human organs and plays an important role in cell proliferation, differentiation and apoptosis during embryogenesis and postnatal development. It has four receptors (EGFR, ErbB-2, ErbB-3 and ErbB-4) and numerous ligands. Dysregulation of the Epidermal Growth Factor signaling network is implicated in the pathogenesis of various disorders. Especially in cancer, the Epidermal Growth Factor system becomes hyperactivated with various mechanisms (ligand overproduction, receptor overproduction, constitutive receptor activation). EGFR overexpression may have a dual role in endometrial cancer. It seems that in type I endometrial cancer, EGFR overexpression did not affect disease progression. However in type II endometrial cancer, EGFR overexpression associated with high grade disease and adverse clinical outcome. Moreover ErbB-2 overexpression especially in type II endometrial cancer, is an indicator of a highly aggressive disease with poor overall survival. The potential role of ErbB receptors (especially EGFR and ErbB-2) as targets for cancer therapy has been investigated for over 20 years. There are 2 major classes of ErbB targeted therapies: anti-ErbB monoclonal antibodies (MoAbs) and ErbB-specific tyrosine kinase inhibitors (TKIs). ErbB targeted therapies have still shown modest effect in unselected endometrial cancer patients. However, they may be clinically active as adjuvant therapy in well-defined subgroups of type II endometrial cancer patients with EGFR and ErbB-2 overexpression.