Treatment of Metastatic Triple-Negative Breast Cancer

The triple-negative breast cancer (TNBC) phenotype, defined as the lack of estrogen and progesterone hormone receptors and the HER2 receptor, represents approximately 15% to 20% of all breast cancer cases. Challenges faced in management of these patients arise from the heterogeneity of TNBC and the absence of well-defined molecular targets. Subgroups derive significant benefit from cytotoxics however, patients with TNBC have higher rates of distant recurrence and a poorer prognosis than women with other breast cancer subtypes overall. Currently, cytotoxic chemotherapy is the only systemic treatment option at all stages of disease, and rational drug selection based on tumor biology remains an aspiration. In the context of relapse, the most efficacious regimens remain undefined and the typical clinical picture is one of rapid disease progression and little durable benefit to therapy. This article reviews current approaches in metastatic TNBC and considers novel therapies in development that may improve the outlook for those with this disease.