ERBB2 and neoplasm: Examples that illustrate the power of this approach are the HER2-targeting antibody trastuzumab (Herceptin®), which was successfully developed specifically in patients with tumor overexpression or amplification of HER2 [5], and the EGFR tyrosine kinase inhibitors gefitinib (Iressa) and erlotinib (Tarceva®), which have shown dramatic anti-tumor activity in patients whose tumors harbor oncogenic mutations in EGFR [6].