Targeted therapy for the HER2 pathway in cancers in general currently relies on three medications with different mechanisms: trastuzumab, an HER2-targeted monoclonal antibody that binds to the extracellular domain; pertuzumab, a recombinant humanized monoclonal antibody that inhibits the heterodimerization of HER2 with other HER2 receptors; and lapatinib, the tyrosine kinase inhibitor against EGFR1 and HER2 [137]. Here, ERBB2 is linked to cancer.