Over the past few years many biological technologies have been invented to prepare therapeutic antibody drugs, including chimeric, humarized or fully human antibodies, radioimmunotherapeutic agents, antibody-drug conjugates (ADCs), and bi-specific T cell engagers (BiTEs), etc. As early as 1998, the FDA approved the use of Trastuzumab, the first anti-HER2 humanized antibody, for HER2-positive breast cancer. This evidence concerns the gene ERBB2 and breast cancer.