New research has emerged from the University of Ohio that could transform treatment for mesothelioma patients. Researchers believe that administering a muscle relaxant called papaverine may help to increase the effectiveness of radiation to reduce or eliminate tumors. This could save the lives of those living with asbestos-related diseases, including mesothelioma.

Radiation for Mesothelioma Can Damage Healthy Cells Too

Mesothelioma is a cancer that’s currently considered incurable, though there are several procedures available to extend and improve the life of mesothelioma patients—including radiation therapy. However, because mesothelioma tumors are irregularly shaped, it’s difficult for radiologists to fully target the tumors. New radiology technology is making it easier to accurately target and destroy mesothelioma tumors.

Despite these advancements, radiation for mesothelioma can take its toll on the body. The therapy doesn’t just destroy cancer cells—it can kill nearby healthy cells too. To undergo mesothelioma-related operations and post-operative treatment, a patient must be in optimum health.

Doctors are trying to find ways to reduce the impact that radiation has on healthy cells to improve the chances of a patient’s recovery.

Using Papervine to Improve Radiation Recovery

Researchers have now discovered that highly oxygenated cells are more susceptible to radiation. Unfortunately, cancer cells, by nature, tend to be less oxygenated, meaning they can withstand radiation better than healthy cells that are more oxygenated. Researchers proposed that by oxygenating mesothelioma cells, it could improve the effectiveness of radiation.

In a recent study, researchers found that by injecting the muscle relaxant, papaverine, before radiation therapy, it would oxygenate the mesothelioma cells and increase the chance of tumor reduction.

The principal investigator of this latest research initiative, Nicholas Denko, PhD, MD, professor of radiation oncology at the OSUCCC, says: “We found that one dose of papaverine prior to radiation therapy reduces mitochondrial respiration, alleviates hypoxia, and greatly enhances the responses of model tumors to radiation.”

What Is Papervine’s Impact on Radiation Therapy?

Papaverine was first used as a muscle relaxant in 1948 but it wasn’t until October 2018 that researchers linked the drug to radiation therapies. Though it’s been an FDA-approved product for decades, researchers have only recently discovered that it also inhibits the respiration of microconidia, which consume oxygen in cells. This can help to increase the effectiveness of radiation for mesothelioma.

Oxygen levels play a huge part in response to radiation therapy. Cancer cells typically contain lower oxygen levels than healthy cells, which means that they are less likely to succumb to the effects of radiation. Papaverine works by increasing the levels of oxygen in the blood before radiation, which can make the tumors more sensitive to treatment and, therefore, more targeted. This can help to reduce the tumor size and work towards eliminating cancerous cells.

Researchers at the University of Ohio have been working to increase oxygen delivery to cancerous cells, with inconclusive results. However, after identifying FDA-approved papaverine as an inhibitor of mitochondrial complex I, they found genetic evidence to show that the drug can oxygenate the cells.

Scientists also believe that papaverine may have a positive side effect of radiosensitizing cancer cells only, meaning that well-oxygenated, healthy cells will remain intact.

Future Testing in Clinical Trials Is Promising

Clinical researchers are constantly looking for new ways to improve standard mesothelioma therapies. Because mesothelioma is currently incurable, the goal is to make the current standard of care more effective so patient’s don’t have to undergo as many different treatment rounds.

The research in this field will be continued as doctors look for other varieties of papaverine that may deliver similar results. As of yet, the theory cannot be put into practice, but specialists hope that papaverine will make it to clinical trials in the not-so-distant future.

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Sources
  1. “Papaverine and its derivatives radiosensitize solid tumors by inhibiting mitochondrial metabolism”. Retrieved from: https://www.pnas.org/content/115/42/10756. Accessed on December 15, 2018.
  2. “Abstract 5841: Hypoxic tumors can be sensitized to radiation therapy by repurposing papaverine as an inhibitor of mitochondrial respiration”. Retrieved from: http://cancerres.aacrjournals.org/content/77/13_Supplement/5841. Accessed on December 15, 2018.
  3. “A 150-year-old drug might improve radiation therapy for cancer”. Retrieved from: https://www.sciencedaily.com/releases/2018/10/181017172829.htm. Accessed on December 15, 2018.

Last modified: December 19, 2018