Neoadjuvant and Adjuvant Chemotherapy Considerations for Triple-Negative Breast Cancer

Triple-negative breast cancers (TNBC) are an immunohistochemically defined subset of breast cancer that is negative for the estrogen receptor (ER), progesterone receptor (PR), and HER2, and represent a heterogeneous group of tumors based on expression profiling. Despite strides made in adjuvant chemotherapy regimens and in overall survival for patients with breast cancer, prognosis for patients with TNBC continues to lag behind those with ER+ or HER2+ tumors. Chemotherapy remains the standard of care for TNBC because no targeted therapies have been proven to be effective for this subtype. There is growing interest in the use of platinum agents in the neoadjuvant setting for TNBC but we await data from ongoing, randomized, adjuvant trials to understand if these agents have an impact on long-term outcomes. Patients with BRCA-mutant TNBC are a special subgroup who may benefit more from platinums and, potentially, from poly ADP ribose polymerase (PARP) inhibitors. Immune checkpoint inhibitors are promising in many cancer types and are investigational in combination with chemotherapy in the neoadjuvant setting. Growing attempts to develop biomarkers to guide therapy within TNBC may lead to more effective regimens or to novel therapeutic targets.