Nanomedicine in Oncology: Targeted Drug Delivery Systems and Their Clinical Applications

Nanomedicine represents a paradigm shift in oncology, offering unprecedented precision in cancer diagnosis and therapy. This review synthesizes advancements in nanoparticle-based drug delivery systems (DDS) designed to overcome biological barriers, enhance tumor targeting, and minimize systemic toxicity. We critically evaluate clinically approved nanotherapeutics including liposomal doxorubicin, albumin-bound paclitaxel, and polymeric micelles detailing their mechanisms, efficacy, and limitations. Emerging platforms such as stimuli-responsive nanoparticles, extracellular vesicles, and multifunctional theranostic agents demonstrate enhanced tumor penetration and real-time treatment monitoring in preclinical models. Clinical trial data reveal that nanoparticle albumin-bound (nab)-paclitaxel improves response rates by 30-50% in metastatic breast and pancreatic cancers compared to solvent-based formulations. However, challenges persist: only 0.7% of administered nanoparticles reach solid tumors due to biological barriers, and scale-up complexities hinder translation. This analysis further explores engineering solutions to enhance the enhanced permeability and retention (EPR) effect, strategies to mitigate immune clearance, and innovations in ligand-based targeting. With over 80 nanomedicines in clinical trials and next-generation platforms enabling tumor microenvironment remodeling, nanomedicine holds transformative potential for precision oncology pending resolution of manufacturing, regulatory, and accessibility hurdles.