Cerenkov Radiation-Induced Photoimmunotherapy with F-FDG.

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with toxicity induced by photoabsorbers after irradiation with NIR light. A limitation of NIR-PIT is the inability to deliver NIR light to a tumor located deep inside the body. Cerenkov radiation (CR) is the ultraviolet and blue light that is produced by a charged particle traveling through a dielectric medium faster than the speed of light in that medium and is commonly produced during radioactive decay. Here, we demonstrate the feasibility of using CR generated by F-FDG accumulated in tumors to induce photoimmunotherapy. Using A431-luc cells, we evaluated the therapeutic effects of CR-PIT in vitro and in vivo using bioluminescence imaging. CR-PIT showed significant suppression of tumor size, but the decrease of bioluminescence after CR-PIT was not observed consistently over the entire time course. Although CR-PIT can induce tumor killing deep within body, it is less effective than NIR-PIT, possibly related to the relatively lower efficiency of short wavelength light than NIR.