Targeted Drug Delivery Systems for Breast Cancer Therapy: Advances in Nanomedicine

Abstract

Breast cancer remains one of the leading causes of cancer-related morbidity and mortality among women worldwide, despite significant advances in early detection and systemic therapy. Conventional chemotherapy is often limited by poor tumor selectivity, dose-limiting toxicity, multidrug resistance, and inadequate intracellular drug accumulation. Targeted drug delivery systems enabled by nanomedicine have emerged as a transformative strategy to overcome these barriers by improving pharmacokinetics, enhancing tumor localization, and enabling molecularly guided therapy. This review critically examines the design principles, mechanistic foundations, and translational progress of nanotechnology-based targeted drug delivery systems for breast cancer therapy. Passive targeting through the enhanced permeability and retention effect and active targeting using ligand–receptor interactions are discussed in relation to tumor microenvironment heterogeneity, vascular permeability, and cellular internalization pathways. Major nanocarrier platforms, including liposomes, polymeric nanoparticles, dendrimers, inorganic nanostructures, and biomimetic systems, are analyzed with respect to drug loading capacity, release kinetics, biocompatibility, and clinical scalability. Particular attention is given to receptor-specific targeting strategies directed against HER2, estrogen receptors, folate receptors, and CD44, as well as emerging stimuli-responsive and theranostic systems. Recent preclinical and clinical evidence highlights meaningful improvements in therapeutic index, reduced systemic toxicity, and enhanced treatment personalization. Remaining challenges related to immunogenicity, manufacturing reproducibility, regulatory pathways, and long-term safety are critically evaluated. Overall, nanomedicine-based targeted delivery offers a compelling pathway toward precision breast cancer therapy and supports the continued integration of advanced materials science with molecular oncology for improved patient outcomes.