Herceptin (Trastuzumab), a humanized monoclonal antibody targeting HER-2/neu, has shown some benefit as a treatment for patients with HER-2/neu-expressing breast cancer, but clinical studies show that patients with high levels of HER-2/neu who are treated with a single dose of Herceptin progress to metastatic disease within one year [1]–[5]. Here, ERBB2 is linked to breast cancer.