DETROIT - Understanding how light-activated cancer drugs illuminate and destroy malignant tissue is the focus of a recently renewed study by a researcher in WSU's School of Medicine.

David Kessel, Ph.D., professor of Pharmacology in the School of Medicine, and co-Principal Investigator John Reiners, Ph.D., professor in WSU's Institute of Environmental Health Sciences, received $1.2 million from the National Institutes of Health (NIH) to renew research that has been ongoing for 30 years on the use of light-activated drugs, known as photodynamic therapy (PDT), in the treatment of cancer. This extends Kessel's NIH support to a continuous 55 years.

PDT involves intravenously administering a photosensitizing agent designed to bind to cancer cells and tissues. The photosensitized tissues are then irradiated with a red light that penetrates deeply into tissues. The result is the formation of reactive oxygen species that kill the cells and shut down their blood supply. Photosensitizing agents are fluorescent, permitting identification of malignant cells in tissues.

PDT currently is showing some successes in cancer treatment, especially for early-stage cancers that are confined to certain areas, such as skin, esophagus and head and neck. "After surgery, tumor cells often remain at surgical margins," Kessel said. "Photodynamic therapy can be used to clean up these remaining cells, with no adverse effect on adjacent healthy cells."

The technique was originally developed at the Roswell Park Cancer Institute in Buffalo, New York, in the mid-1970s and matured as a feasible medical technology in the 1980s at several institutions throughout the world. Kessel has been studying PDT since 1980, and over time it has become his main focus.

"I found the therapy interesting," he said. "Unlike most cancer drugs, PDT is selective. You can target malignant cells and leave normal cells unharmed."

Kessel's first studies involving PDT focused on determining the composition of some of the early photosensitizing agents, followed by studies on sub-cellular sites of localization. Later, in research aimed at determining the mechanism of PDT, he extended studies relating to the pathway by which irradiation of photosensitized cells leads to death.

Kessel's current study will look at some new effects of PDT, including determining the therapy's effect on cell membrane cycling and whether this plays a role in PDT's ability to destroy cancer cells. "It is very important to understand how a procedure works in order to uncover information about improvements and optimization," he said.

In addition to improved methods for current uses of PDT, Kessel's research could contribute to new applications for cancer treatment. A new focus area being developed at Massachusetts General Hospital is the examination of PDT's potential for use in combination with conventional chemotherapy for the treatment of pancreatic and ovarian cancer. "Cancer treatment is almost always a combination of more than one form of treatment and it is dependent on individual circumstances what combination will work best," Kessel said. "PDT is clearly an excellent tool in eradicating certain cancers and may be useful in the treatment of several others. I look forward to this study helping to uncover valuable information in further utilizing this method."

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