Enhanced nanodrug delivery in tumors after near-infrared photoimmunotherapy

To date, the delivery of nanosized therapeutic agents to cancers largely relies on the enhanced permeability and retention (EPR) effects that are caused by the leaky nature of cancer vasculature. Whereas leaky vessels are often found in mouse xenografts, nanosized agents have demonstrated limited success in humans due to the relatively small magnitude of the EPR effect in naturally occurring cancers. To achieve the superior delivery of nanosized agents, alternate methods of increasing permeability and retention are needed. Near-infrared photoimmunotherapy (NIR-PIT) is a recently reported therapy that relies on an antibody-photon absorber conjugate that binds to tumors and then is activated by light. NIR-PIT causes an increase in nanodrug delivery by up to 24-fold compared to untreated tumors in which only the EPR effect is present. This effect, termed super-EPR (SUPR), can enhance the delivery of a wide variety of nanosized agents, including nanoparticles, antibodies, and protein-binding small-molecular-weight agents into tumors. Therefore, taking advantage of the SUPR effect after NIR-PIT may be a promising avenue to use a wide variety of nanodrugs in a highly effective manner.