Photodynamic Therapy

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 oncological and anti-microbial applications. We currently have an open, Phase 1 clinical trial investigating the use of PDT with methylene blue to treat deep tissue infected abscesses.  Our pre-clinical investigation in antimicrobial PDT is centered on the optimization of PDT drug and light doses in realistic 3D models of complex infection sites, such as abdominal abscesses.

Our pre-clinical efforts in oncological PDT are focused on optimization of photosensitizer delivery, including drug delivery vehicle, route of administration, and tumor targeting. 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 Photofrin, methylene blue, and Pc 4, is ongoing in mouse models as means to avoid this skin photosensitivity and improve uniformity of photosensitizer concentration at the treatment site.

Related publications:

Z. Li, L. Nguyen, D.A. Bass, and T.M. Baran. Effects of patient-specific treatment planning on eligibility for photodynamic therapy of deep tissue abscess cavities: Retrospective Monte Carlo simulation study. Journal of Biomedical Optics 27, 083007 (2022).

S.B. Snell, A.L. Gill, C.G. Haidaris, T.H. Foster, T.M. Baran, and S.R. Gill. Staphylococcus aureus tolerance and genomic response to photodynamic inactivation. mSphere 6, e00762-20 (2021).

T.M. Baran, H.W. Choi, M.J. Flakus, and A.K. Sharma. Photodynamic therapy of deep tissue abscess cavities: Retrospective image-based feasibility study using Monte Carlo simulation. Medical Physics 46, 3259-3267 (2019).

T.M. Baran. Photofrin photodynamic therapy with intratumor photosensitizer injection provides similar tumor response while reducing systemic skin photosensitivity: Pilot murine study. Lasers in Surgery and Medicine 50, 476-482 (2018).

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).