Nanocarriers for Anticancer Drug Targeting: Recent Trends and Challenges

Nanocarriers are nanostructured vehicles employed to deliver anticancer drugs to the targeted tumor sites in the body. Nanocarriers have been successfully employed to circumvent certain limitations of conventional anticancer drug delivery while providing greater bioavailability, prolonged circulation time and higher tumor accumulation for enhanced therapeutic outcomes in cancer treatment. Nanocarriers are also responsive to functionalization to tailor their pharmaco-kinetics and achieve enhanced therapeutic outcomes in cancer therapy. Among organic, inorganic and hybrid type, several nanocarriers have gained approval for use in cancer patients, while many more are under clinical development. For the last two decades, cancer immunotherapy-based advanced targeting approaches such as monoclonal antibodies, antibody drug conjugates and immune checkpoint inhibitors that utilize human immune system functions have vastly developed which furnish better treatment options in several intractable cancers compared with traditional cancer therapies. This review discusses the imperative role of tumor vasculature in passive and active targeting of anticancer drugs using organic and inorganic nanocarriers and the current research efforts underway. The advanced targeting approaches for treatment of various cancers and their most recent clinical development scenario have been comprehensively explored. Further, potential challenges associated with each type of nanocarrier, and their translational obstacles are addressed.