Cara B. Gonzales, D.D.S., Ph.D.

Two for one: Drug kills cancer cells and blocks pain

Cara B. Gonzales, D.D.S., Ph.D., is investigating the anti-pain drug capsazepine and its impact on oral cancer tumors.

Cara B. Gonzales, D.D.S., Ph.D., is investigating the anti-pain drug capsazepine and its impact on oral cancer tumors. Photo by Lester Rosebrock, Creative Media Services

An anti-pain agent has been found to also dramatically shrink human oral cancer tumors in mouse models. The agent, capsazepine, caused no damage to surrounding tissues, researchers from the School of Dentistry and School of Medicine found.

“That’s the beauty,” said Cara B. Gonzales, D.D.S., Ph.D., assistant professor of comprehensive dentistry and an investigator with the Cancer Therapy & Research Center. “Capsazepine kills cancers selectively, leaving normal tissues unharmed, and also acts on neurons to block pain, a desirable combination in a potential medication.”

Oral squamous cell carcinoma is the eighth most common cancer in the U.S. with 40,000 new cases and nearly 8,000 deaths reported annually. Typically, tumors develop on the side of the tongue, and 60 percent of patients have large tumors before seeking help. The five-year survival rate is 30 percent.

But if caught early, the disease is curable, said Randal A. Otto, M.D., FACS, professor and chairman of the Department of Otolaryngology-Head & Neck Surgery in the School of Medicine.

“Anything that selectively attacks the tumor while not injuring the normal tissues can only help the patient,” he said.

Capsazepine was developed to block TRPV1, a calcium channel found in pain-sensing neurons. When TRPV1 is activated, a pain signal is sent to the brain. Capsazepine may reduce oral cancer pain because it blocks tumor-secreted factors from stimulating TRPV1 on these neurons. Dr. Gonzales found that capsazepine also has anti-cancer activity that may be linked with its ability to increase oxidative damage in tumors. Enhanced oxidative stress leads to auto-destruction of the tumor cells, the researchers theorize.

So far, only local administration of capsazepine, directly into the primary tumors, has been tested.

“We would like to be able to deliver this therapy systemically to target metastatic disease,” Dr. Gonzales said. “Our laboratory is working with the Center for Innovation in Drug Discovery, a partnership between the Health Science Center and The University of Texas at San Antonio, to develop novel drugs that are similar to capsazepine, with improved efficacy for the purpose of systemic administration to treat tumors that are inaccessible to local injection or that have metastasized.”

The Health Science Center has claimed intellectual property on results of the study, which is described in the journal Oral Oncology.

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