Cancer Targeting: Responsive Polymers for Stimuli-Sensitive Drug Delivery

Effective treatment of cancer is limited by the lack of delivery technology to specifically and efficiently deliver chemotherapeutic agents within the tumor vicinity. The tumor targeting based on ligand or antibody conjugation to therapeutics is limited by the chemistry, stability and scalability issues. Recently, functional polymers which are responsive to internal and external stimuli have been developed. Stimuli-responsive carriers show potential to overcome the limitations of cancer targeting. Internal stimuli localized to cancer tissue including pH, redox potential, extracellular enzyme expression can be utilized to target tumors. Furthermore, polymer responsiveness to external stimuli, including temperature, magnetic field, ultrasound and light can be utilized to localize the nanocarriers to specific tumor location after administration. The present review provides an overview of the current status of development of responsive polymers for various stimuli to target cancer.