Advanced Triple-Negative Breast Cancer: Emerging Therapies and a Changing Treatment Landscape

Triple-negative breast cancer (TNBC) is characterized by the lack of estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2 overexpression. Historically, treatment options for TNBC have been limited, because of the absence of actionable targets. The addition of immune checkpoint inhibitors to chemotherapy improved outcomes for a subset of patients with metastatic PD-L1-positive disease; however, a critical need for more effective therapies remains. Antibody-drug conjugates (ADCs) have been a promising advance in the management of advanced TNBC and are reshaping the landscape as they move earlier into the treatment algorithm. A greater understanding of the molecular heterogeneity of TNBC has enabled the pursuit of more targeted and personalized therapeutic strategies. Despite this, TNBC continues to have the least favorable outcomes compared with other breast cancer subtypes. This review highlights current evidence and future challenges in advanced TNBC, including optimizing therapeutic sequencing and the ongoing need for predictive biomarkers and novel agents.