A cancer vaccine consisting of a proprietary, recombinant modified vaccinia Ankara (MVA) viral vector encoding an epitope of human epidermal growth factor receptor 2 (HER2) with potential antineoplastic activity. Upon administration, modified vaccinia Ankara (Bavarian Nordic)-HER2 vaccine may stimulate the host immune system to mount humoral and cytotoxic T lymphocyte responses against HER2-expressing tumor cells, resulting in tumor cell lysis. HER2, also known as ErbB-2, is a tyrosine kinase growth factor receptor and a member of the epidermal growth factor receptor family; it plays a significant role in the pathogenesis of some breast cancers.