Repurposing an Antiparasitic Drug to Treat Brain Tumors

Researchers examined if a common medication administered to treat pinworms could replace the current treatment used for certain brain cancers. [Pixabay]

With the enormous number of drugs approved for the treatment of disease, many researchers and biopharma companies are looking to repurpose these compounds on diseases for which they were never originally intended. This approach has numerous advantages, as companies would lay out much less in expenditures since these drugs have already gone through extensive development. Moreover, if the repurposed drug proves to be effective, the approval process will be shortened considerably, allowing physicians to offer potentially better treatment options much sooner.

Researchers at the Karches Center for Oncology Research within The Feinstein Institute for Medical Research are taking advantage of this approach and have recently published findings showing that a common medication administered to treat pinworms could replace the current treatment for one of the most common types of brain tumors—low-grade glioma. The findings from this study were published recently in Molecular Medicine in an article entitled “Repurposing Mebendazole as a Replacement for Vincristine for the Treatment of Brain Tumors.”

Low-grade glioma is a tumor that originates from cells that support and protect the brain's nervous system. Treatments for these tumors include surgery, radiotherapy, and chemotherapy. Brain tumor chemotherapy is challenging, as most drugs cannot penetrate the blood–brain barrier, a natural defense mechanism that prevents substances in the bloodstream from getting into the brain. For example, vincristine is commonly used as part of a drug cocktail for the treatment of brain tumors, even though it is rather toxic and very poorly crosses the blood–brain barrier.

In the search for improved alternatives, the Feinstein Institute team focused their attention on mebendazole, a medication that is used to treat parasitic pinworms and that in previous studies had been found to be effective in the treatment of glioma tumors. By studying how mebendazole kills isolated tumor cells in the laboratory, they showed that it works in the same way as vincristine. Furthermore, the researchers found that while mebendazole effectively slowed down the growth of glioma tumors, vincristine did not work at all.

“We were rather surprised to see that vincristine, which is currently used to treat a range of different brain tumors, was totally ineffective in our in vivo glioma model,” explained senior study investigator Marc Symons, Ph.D., a professor at The Feinstein Institute for Medical Research. “In contrast, in the same model, mebendazole performed quite well, most likely because mebendazole crosses the blood–brain barrier and reaches the tumor much better than vincristine. The reason that vincristine may be erroneously believed to be effective for the treatment of brain tumors is that it always has been used in combination with other treatments.”

Based on their new findings—and the fact that vincristine often has severe side effects in comparison to relatively mild reactions to mebendazole—Dr. Symons and his team are now looking to initiate clinical trials to test whether vincristine can be exchanged by mebendazole in the treatment of brain tumors.

“Sometimes innovation can be looking at an existing treatment in a new light,” concluded Kevin Tracey, M.D., president and CEO of the Feinstein Institute. “This new approach needs to be tested in clinical trials, but with Dr. Symons' new findings we may be closer to a new treatment option that could prolong the lives of the patients suffering from low-grade glioma and other brain tumors.”