A monoclonal antibody directed against the human epidermal growth factor receptor 2 (HER2) with potential immunomodulating and antineoplastic activity. After binding to HER2 on the tumor cell surface, anti-HER2 monoclonal antibody CT-P6 may induce a cytotoxic T-lymphocyte (CTL) as well as an antibody-dependent cell-mediated cytotoxicity (ADCC) against tumor cells that overexpress HER2. HER2, a tyrosine kinase receptor, is overexpressed by many cancer cell types.