Biochemical Precision: Enzyme-Responsive Drug Delivery Systems in Cancer Therapy

Abstract: Systemic toxicity and low efficiency hinder effective cancer therapies, but Targeted Drug Delivery Systems (TDDS) offer a promising solution by focusing drug action on tumor sites, sparing healthy tissues. Among these, Enzyme-Responsive Drug Delivery Systems (ERDDS) utilize the elevated enzyme activity in the tumor microenvironment to trigger drug release. Tumor-specific enzymes such as proteases, lipases, hydrolases, lysyl oxidases, glycoxidases and oxidoreductases act as activators, ensuring precise drug release. ERDDS design involves selecting suitable carriers like polymers, nanoparticles, or lipids and incorporating enzymatically sensitive components. Based on their architecture, ERDDS are categorized into polymeric, lipid-based, inorganic, or hybrid types, each with distinct mechanisms of action. These systems have applications in various combination therapies as well as chemotherapy, gene therapy, immunotherapy, radiation therapy and photodynamic therapy, offering enhanced treatment efficacy and reduced side effects compared to conventional DDS. Despite the advantages of enzyme-responsive nano-DDS, significant challenges like scalability, enzymatic variability, resistance, toxicity, poor tumor distribution, premature drug release from liver hydrolases, and issues with solubility, stability, and unpredictable release in TDDS must be addressed for clinical viability, though combinatorial therapies offer promise in overcoming these obstacles. Ongoing clinical trials and market evaluations provide insight into regulatory hurdles and the potential for ERDDS in future therapies. Emerging technologies like CRISPR-based enzyme systems and theranostics are also expected to shape the future of cancer treatments. ERDDS represent a personalized, selective, and effective approach to drug delivery, with the potential to improve patient outcomes and advance cancer care by integrating combination therapies and cutting-edge innovations.