Photodynamic therapy (PDT) uses a photoreactive drug or photosensitizer in combination with a specific wavelength of light to kill tumor tissue. PDT destroys tumor tissue through multiple, interacting mechanisms that include direct photodynamic cell kill, microvascular disruption and inflammation.

Clinical trials have shown a palliation of advanced disease and long-term control of early disease. PDT is approved for multiple indications in the U.S., Canada, Japan and the European Union. Numerous pre-clinical studies have demonstrated that PDT enhances the host anti-tumor immune response, but the mechanisms behind this enhancement are unknown. Among the potential contributing factors are alterations in the tumor microenvironment via stimulation of pro-inflammatory cytokines, and direct effects of PDT on the tumor that increase immunogenicity.

You can learn more about the use of PDT in the clinic by following these links from the PDT Center at Roswell Park Cancer Institute; the National Cancer Instituteand the American Cancer Society.