EGFR signaling and drug discovery.

Dysregulation of human epidermal growth factor receptor (ErbB/HER) pathways by over-expression or constitutive activation can promote tumor processes including angiogenesis and metastasis and is associated with poor prognosis in many human malignancies. In addition to cancer, ErbB signaling has also been implicated in cardiovascular and neurodegenerative diseases. Conversely, inhibition of ErbB pathways with targeted agents, such as monoclonal antibodies (MoAbs) or tyrosine kinase inhibitors (TKIs), blocks cell cycle progression, inhibits the production of pro-angiogenic factors and induces apoptosis in numerous in vitro and xenograft models. Accordingly, the ErbB receptor family with their most prominent members EGFR and HER-2 represents validated targets for anti-cancer therapy, and anti-ErbB MoAbs (cetuximab, panitumumab, and trastuzumab) and TKIs (gefitinib, erlotinib, and lapatinib) have now been approved for the treatment of advanced colorectal cancer, squamous cell carcinoma of the head and neck, advanced non-small-cell lung cancer, as well as pancreatic and breast cancer. Although results have been encouraging, more work remains to be done.