Advanced Targeted Drug Delivery Systems for Cancer Therapy: From Conventional Approaches to Precision Medicine

Cancer remains one of the major causes of morbidity and mortality worldwide, despite substantial advances in surgery, radiotherapy, chemotherapy, molecularly targeted therapy, and immunotherapy. Conventional antineoplastic chemotherapy remains an important component of cancer treatment; however, its clinical utility is frequently limited by nonspecific distribution, systemic toxicity, poor pharmacokinetics, inadequate tumor accumulation, multidrug resistance, and tumor heterogeneity. Targeted drug delivery systems have emerged as an important strategy for improving the therapeutic index of anticancer agents by modifying drug distribution and facilitating preferential delivery to tumors or specific cellular and molecular targets. Early nanomedicine approaches primarily relied on passive tumor accumulation associated with the enhanced permeability and retention effect, whereas contemporary systems increasingly incorporate active ligand-mediated targeting, stimuli-responsive release, biomimetic carriers, and molecularly guided therapeutic strategies. Major platforms include liposomes, polymeric nanoparticles, polymeric micelles, lipid-based nanoparticles, dendrimers, antibody–drug conjugates, and biomimetic or extracellular-vesicle-based systems. These systems can improve drug solubility, stability, circulation time, cellular uptake, and controlled release while potentially reducing exposure of healthy tissues. Nevertheless, clinical translation remains challenging because of tumor heterogeneity, biological barriers, variable tumor accumulation, protein-corona formation, manufacturing complexity, scalability, toxicity, and regulatory requirements. Precision medicine provides an emerging framework in which molecular profiling, biomarkers, and patient-specific tumor characteristics can guide the selection and design of targeted delivery systems. This review discusses the evolution, principles, major platforms, targeting strategies, stimuli-responsive systems, clinical translation, limitations, and future prospects of targeted drug delivery for antineoplastic therapy, with particular emphasis on the transition from conventional chemotherapy toward precision nanomedicine.