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Researchers assess pinworm medication for adults, children with glioblastoma
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Researchers at Johns Hopkins University are conducting the first clinical trials to evaluate the potential of a pinworm medication for the treatment of children and adults with newly diagnosed glioblastoma.
Mebendazole has been used for more than 40 years to treat parasitic infections.
Although the medication requires further testing in patients with cancer, results of a phase 1 trial have shown the medication is safe for and tolerated by adults with glioblastoma. An additional phase 1 trial is underway to assess the agent in children.
“The idea to test mebendazole in [patients with cancer] came about after the brain tumors in our lab animals stopped growing when they were treated for a pinworm infection,” Gregory J. Riggins, MD, PhD, director of the division of neurosurgery research, and professor of neurosurgery and oncology at Johns Hopkins University, told HemOnc Today. “It turns out that the entire mouse colony had been treated to prevent the spread of pinworm infection. In turn, mebendazole prevented the growth of the tumors.”
Prior studies showed these antiparasitics potentially could slow the growth of various tumors. However, the effect on brain tumors had not been studied, so Riggins and colleagues decided in 2009 to evaluate mebendazole in a clinical trial for glioblastoma.
Riggins spoke with HemOnc Today about the research and the potential role of this agent in cancer care.
Question: What investigations have been conducted so far , and what have results shown?
Answer: We have conducted preclinical research and molecular research in which we have studied the mechanism of the drugs. We found mebendazole worked best out of this class of antiparasitics. Besides binding tubulin and preventing tubulin formation, it appears the drug acts as a kinase inhibitor to prevent signaling and subsequently prevents blood vessel growth in the tumors. This seems to be one of the factors that contributes to slowed tumor growth. We have also looked at different animal models to determine in which patients mebendazole will work, and we found it is effective in animal models against glioblastoma, medulloblastoma and other types of brain cancers. We have taken the drug to a phase 1 safety study, and we improved the formulation of the drug and studied its pharmacokinetics to make it more effective for cancer use. We established the safety of the drug in 21 adults with newly diagnosed glioblastoma.
Q: What are the next steps in research?
A: The next big step for brain tumors is to show that we have a survival benefit in a randomized phase 2 study. The first phase 2 study will include adults, but we have a parallel phase 1 study for childhood brain tumors that has just begun. The children’s studies take a little longer, so we wanted to establish safety first in adults with brain tumors before we moved on to children. The phase 1 pediatric trial is enrolling, and we are working on raising funding for and designing a new phase 2 trial in adults with newly diagnosed glioblastoma.
Q: How long will it take until researchers can determine whether there is real potential for this agent?
A: The phase 2 trial will most likely take about 1 year to launch. Then it will be about 4 years until we know if there is potential efficacy with this agent.
Q: What are the implications if a readily available, low-cost agent like this is proven safe and effective?
A: This is an unusual situation, as we have come further than initially thought, which is a good surprise. We really need to rethink the overall cancer drug pipeline. A drug can go through the normal pharmaceutical mechanism process, but the implication — if the drug works — is that it could replace more expensive options or it could provide an effective cancer therapy to areas and populations that cannot necessarily afford to develop a new cancer drug. The average new cancer drug costs more than $100,000 per year. This drug would be a magnitude less.
Q: Is this repurposing approach something you and colleagues expect to see more of going forward?
A: Yes, both with this drug and with other drugs. This approach may be the only available option for underserved populations, and we expect to figure out how to identify the different repurposed drugs and how to combine them more effectively for combination therapy. I expect that we will see more of this once we figure out how to develop this new system of cancer research and drug redevelopment.
Q: Is there anything else you would like to mention?
A: There is one important aspect of this that makes it successful. Mebendazole has a 40-year track record of safe use. We already know it is difficult, if not impossible, to reach toxic levels with mebendazole. There is a limited number of compounds that we can safely use in the human body and even less that we have identified for safe use. Many new drugs fail because of toxicity or an adverse event, so if these repurposed drugs have the potential to be efficacious, it could [dramatically reduce] the 15- to 20-year period it normally takes to reach approval. Additionally, we have already established the safety concerns upfront, which affects the cost of development and makes it more likely that the drug will succeed in clinical trials. – by Jennifer Southall
For more information:
Gregory J. Riggins, MD, PhD, can be reached at Johns Hopkins University, 242 Garland Hall, Baltimore, MD 21218; email: griggin1@jhmi.edu.
Disclosure: Riggins is an inventor on intellectual property related to an improved version of mebendazole for cancer use. Johns Hopkins University manages this patent and any associated income through its conflict-of-interest policies.