Targeting Multidrug Resistance in Cancer: Advances in Precision Medicine and Exosome Therapeutics

Multidrug resistance (MDR) in cancer remains a major obstacle to effective therapy, accounting for most chemotherapy failures and disease recurrences. This chapter provides a comprehensive overview of the molecular, cellular, and microenvironmental mechanisms underlying MDR, including the overexpression of drug efflux transporters, alterations in drug targets, enhanced DNA damage repair, epithelial-to-mesenchymal transition (EMT), and the modulatory role of the tumor microenvironment. Recent advances in pharmacological modulation, gene-based therapies, and immunotherapy are discussed, with particular attention to emerging modalities that integrate nanotechnology and precision medicine to restore chemosensitivity. Nanocarrier systems such as liposomes, polymeric nanoparticles, dendrimers, and exosomes have shown significant promise in enhancing drug accumulation, overcoming efflux-mediated resistance, and improving therapeutic selectivity. A major emphasis is placed on exosome-based strategies, highlighting their dual roles as mediators of resistance and as engineered drug-delivery vehicles that transport chemotherapeutics, siRNAs, or CRISPR/Cas constructs to reprogram resistant tumor cells. The chapter also explores exosome engineering, tumor microenvironment reprogramming, and combination therapies that synergistically integrate immunomodulation and gene silencing. Collectively, these insights underscore the need for integrated, patient-specific therapeutic approaches that combine nanotechnology, gene editing, and immunotherapy to effectively counteract multidrug resistance and improve clinical outcomes in cancer treatment.