Neoadjuvant chemotherapy for "Triple Negative" breast cancer: a review of current practice and future outlook

Patients with breast cancer who achieve a complete pathologic response (pCR) after preoperative (neoadjuvant) chemotherapy have an improved prognosis compared to those with residual disease; pCR being a good surrogate of long-term survival and cure from breast cancer. Despite their relative chemosensitivity, less than 25% of all patients with HER2/neu negative (0-2+), and hormone receptors (HR) negative tumors, so-called "Triple Negative" breast cancer (TNBC) treated with standard preoperative chemotherapy achieve pCR. Among patients with residual disease (no pCR) following neoadjuvant chemotherapy, patients with TNBC have the worst prognosis and overall survival. These patients lack the benefit of subsequent targeted therapy. Many studies have addressed improving the efficacy of neoadjuvant chemotherapy by including different cytotoxic agents, biologic modifiers, regimens, and schedules. Up to now, apart from trastuzumab for HRE2/neu+ tumors, none of the targeted agents can be considered a standard therapeutic option for primary systemic treatment. We hereby review the current literature on neoadjuvant chemotherapy for breast cancer, emphasizing treatment of TNBC. We also discuss potentially new therapeutic strategies that target this high risk group.