Exosomal nanocarriers for targeted drug delivery in cancer therapy

Cancer continues to pose a major global health burden, with conventional therapies often hindered by systemic toxicity, drug resistance, and poor tumor specificity. Exosomes, nanoscale extracellular vesicles (EVs) naturally secreted by cells, have emerged as superior nanocarriers for targeted cancer therapy compared with synthetic carriers such as liposomes or polymeric nanoparticles, due to their intrinsic biocompatibility, low immunogenicity, and ability to cross biological barriers. This review explores the therapeutic potential of exosome-based nanocarriers, highlighting their applications in the delivery of chemotherapeutic agents, RNA therapeutics, and CRISPR/Cas9 systems. EVs have been successfully engineered to encapsulate drugs such as paclitaxel, doxorubicin, and cisplatin, achieving improved targeting efficiency, reduced off-target toxicity, and enhanced therapeutic outcomes across multiple cancer models. Notably, studies indicate that paclitaxel-loaded exosomes have exhibited 50-fold higher cytotoxicity against resistant cells in vitro, and achieved in vivo efficacy comparable to 1000 times the dose of free drug. Moreover, EVs have demonstrated remarkable capabilities in delivering functional RNAs (miRNAs, lncRNAs, siRNAs) and genome-editing tools, allowing for gene silencing or correction in tumor environments. Despite these advances, challenges remain regarding their isolation, heterogeneity, scalability, and stability. Addressing these limitations is crucial for clinical translation. Future directions include the development of multifunctional and hybrid EVs with enhanced drug loading and targeting capacities, and integrating exosome-based platforms into personalized and combinatorial cancer treatment regimens.