Potential and Applications of Mn Complexes in Breast Cancer

Breast cancer remains one of the leading causes of mortality among women worldwide, and triple-negative breast cancer continues to show poor clinical outcomes due to the absence of actionable targets. As platinum-based therapies face well-recognized limitations related to toxicity, resistance, and restricted mechanisms of action, manganese (Mn) complexes have recently attracted interest as non-platinum metallodrugs with multimodal antitumor activity, including DNA interaction, Fenton-like ROS generation, and immunomodulation such as activation of the cGAS-STING pathway. This narrative review summarizes studies identified through PubMed and Web of Science searches up to April 2025 and integrates current progress on Mn complexes in breast cancer, including their cytotoxic effects, immune-related functions, and emerging theranostic applications. Representative complexes are compared in terms of structure, activity, and early structure-activity features. At the same time, key translational challenges-including solubility, kinetic and redox stability, bioavailability, and Mn-specific toxicity such as neurotoxicity-are highlighted alongside the limited pharmacokinetic and safety data currently available. Overall, this review outlines both the therapeutic potential and the practical limitations of Mn complexes and identifies research priorities needed to advance these agents toward meaningful clinical translation in breast cancer.