A medication once used to treat pinworms may hold new promise in the fight against a rare and deadly skin cancer, according to a new study led by researchers at the University of Arizona Cancer Center.
The study, published in the Journal of Clinical Investigation, reveals that pyrvinium pamoate—a drug approved in the 1950s to treat intestinal parasites—can stop and even reverse tumor growth in models of Merkel cell carcinoma (MCC), an aggressive form of skin cancer.
Merkel cell carcinoma is a fast-growing neuroendocrine cancer that starts in the skin and is known to be three to five times more deadly than melanoma.
Though rare, MCC cases are increasing, and the current treatment options—such as surgery, radiation, and immunotherapy—often fail to produce lasting results. This has left researchers searching for more effective and broadly applicable treatments.
“Even though it’s a rare cancer, Merkel cell carcinoma behaves like many other cancers,” said Dr. Megha Padi, senior author of the study and assistant professor at the University of Arizona College of Science. “It’s increasing in incidence and needs better treatment options.”
In this study, Dr. Padi and her team tested the effects of pyrvinium pamoate in lab-grown MCC cells and in mice with MCC tumors. They found that the drug was able to halt the growth of cancer cells and even reverse some of the cellular characteristics that make Merkel cell carcinoma so aggressive. In mice, the treatment significantly reduced tumor size.
Pyrvinium pamoate has already shown anti-cancer effects in studies of other cancers, including breast, colon, pancreas, and bladder cancers. This is the first time it has been studied specifically in MCC.
Interestingly, the researchers were drawn to pyrvinium pamoate because it blocks a cellular communication system called the Wnt signaling pathway. This pathway plays a role in many biological processes, including how cells grow and develop.
In MCC, it appears the Wnt pathway becomes overactive and contributes to cancer formation. Since pyrvinium pamoate is known to inhibit this pathway, the team saw it as a strong candidate for testing.
The researchers also offered a theory for why a drug developed to kill parasites might be effective against cancer. “Tumors are a little bit like parasites,” Dr. Padi explained. “Both need to steal resources from the body to survive and grow. If they rely on the same survival pathways, then a drug that works against one might work against the other.”
While these early results are encouraging, Dr. Padi emphasized that more research is needed before pyrvinium pamoate can be used as a standard treatment for Merkel cell carcinoma. Future studies will need to determine the most effective doses, possible side effects, and how the drug might be combined with existing treatments.
Still, the discovery offers new hope for patients with MCC and may even help guide treatment development for other cancers with similar biological traits. What began as a simple pinworm medicine could one day become a powerful weapon in the fight against one of the most aggressive forms of skin cancer.
If you care about skin health, please read studies about top signs of diabetic skin disease, and Mediterranean diet could help lower the skin cancer risk.
For more health information, please see recent studies about eating fish linked to higher risk of skin cancer, and results showing how to combat the effects of aging on your skin.
The research findings can be found in Journal of Clinical Investigation.
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