Photodynamic therapy (PDT) relies on the combination of a photosensitive drug, known as a photosensitizer, with light of the proper wavelength and molecular oxygen to generate cytotoxic reactive oxygen species. PDT is FDA-approved for a number of cancer indications, and is used off-label for many other oncologic and anti-microbial applications. We currently have an open, Phase 1 trial investigating the use of PDT with methylene blue to treat deep tissue infected abscesses (https://clinicaltrials.gov/ct2/show/NCT02240498). Other clinical applications that we are pursuing include cholangiocarcinoma and early stage head and neck cancer.
Our pre-clinical efforts in PDT have focused on optimization of photosensitizer delivery, including drug delivery vehicle and route of administration. One of the main side effects of PDT is systemic skin photosensitivity, caused by skin uptake of photosensitizer administered intravenously. Investigation of intratumor administration of a number of photosensitizers, including methylene blue and Pc 4, is ongoing in mouse models as means to avoid this skin photosensitivity.
T.M. Baran, B.R. Giesselman, R. Hu, M.A. Biel and T.H. Foster. Factors influencing tumor response to photodynamic therapy sensitized by intratumor administration of methylene blue. Lasers in Surgery and Medicine 42, 728-735 (2010).
T.M. Baran and T.H. Foster. Fluence rate-dependent photobleaching of intratumorally-administered Pc 4 does not predict tumor growth delay. Photochemistry and Photobiology 88, 1273-1279 (2012).
T.M. Baran, O. Mironov, A.K. Sharma and T.H. Foster. Indwelling stent embedded with light emitting diodes for photodynamic therapy of malignant biliary obstruction. CardioVascular and Interventional Radiology 39, 916-919 (2016).