Immunological Approaches in the Treatment of Metastasized Breast Cancer

A better understanding of tumor biology has led to the development of a number of antibody-based targeted therapies in breast cancer. Several of these newer agents, such as trastuzumab and bevacizumab have demonstrated clinical activity and have improved the treatment of patients with metastatic breast cancer (MBC). Trastuzumab is a monoclonal antibody that binds to the extracellular domain of the HER2 receptor. The addition of trastuzumab to chemotherapy and also to endocrine therapy has enhanced efficacy of treatment. New antibody-based strategies directed against HER2 are under development. These new approaches include pertuzumab, an antibody with a different binding epitope that inhibits dimerization of HER2 with other members of the HER receptor family and TDM1, a trastuzumab-based antibody chemotherapeutic conjugate. Another approach to the treatment of solid tumors is inhibition of angiogenesis. The anti-VEGF antibody bevacizumab has been approved for treatment of MBC. Although the mechanism of action is still under investigation, bevacizumab is tested in other clinical settings such as adjuvant therapy, maintenance therapy, and in combination with both chemotherapy and other targeted agents. In this review, we will summarize the most important studies on trastuzumab and bevacizumab, and describe new antibodies currently under clinical development.