Copper complexes in the triple-negative breast cancer landscape: advances and opportunities

Triple-negative breast cancer (TNBC) is a subset of mammary tumors with heterogeneous biology, lacking estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2). Patients generally exhibit an aggressive course, less favorable disease-specific outcomes, and a higher propensity for early recurrence, with chemotherapy remaining the primary systemic treatment eligible for all patients. In this sense, efforts are urgent to identify new effective compounds, aiming to increase disease-free and overall survival. Copper complexes have emerged as promising in oncology by regulating redox balance and modulating hallmarks such as proliferation, apoptosis, epithelial-mesenchymal transition, and angiogenesis. Furthermore, complexes containing copper tend to have low adverse effects. In TNBC, copper compounds may represent at least one component of a multi-action management strategy, being potentially effective against these tumors. The focus of this review is to provide information on TNBC biology and the role of copper in its signaling pathways, addressing the current copper complexes that have been explored to improve treatment.