ERBB2 and metastatic colorectal cancer: To date, several HER targeting agents have been approved for treatment of human cancers including metastatic colorectal cancer [anti-EGFR monoclonal antibodies (mAbs) cetuximab and panitumumab], non-small cell lung cancer [tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib] ,early stage and metastatic breast (anti-HER-2 mAbs trastuzumab and pertuzumab, and dual EGFR/HER2 TKI lapatinib), head and neck (cetuximab), metastatic stomach cancers (trastuzumab) and pancreatic (erlotinib).