Current Issues of Targeted Therapy in Metastatic Triple-Negative Breast Cancer

Patients with triple-negative breast cancer are characterized by a poor prognosis compared with patients with other breast cancer subtypes. The angiogenesis inhibitor bevacizumab is effective in the palliative treatment of patients with triple-negative breast cancer as well as in other breast cancer subtypes. PARP inhibitors represent the first group of targeted agents to be developed under the particular aspect of treating patients with hereditary and triple-negative breast cancer. In addition, an increasing number of studies have demonstrated a significant and clinically relevant change in phenotype between primary tumor and metastasis. Consequently, it should be an essential component of the design of modern clinical trials of targeted agents in metastatic breast cancer to determine the relevant tumor phenotype and, depending on the clinical situation, confirm the presence of the therapeutic target in metastatic lesions.