What do an anti-parasitic drug used to treat pinworms and a frequently used anti-malarial drug have in common? According to recent studies from the labs of Johns Hopkins and University of Kentucky investigators, both mebendazole and chloroquine could be promising medicines to combat cancer.
Mebendazole has been in use as an anti-helminthic drug since 1971. Within the last few years, mebendazole has been added to the growing list of medications that are part of a movement to repurpose already FDA-approved drugs for novel or unexpected purposes. This renewed interested in already approved pharmaceuticals has stemmed from the immense amount of time, money and research that must be put in after identifying a novel compound before the drug can move on to clinical trials, with the time from target identification to FDA approval averaging 14 years.
By testing compounds that have already passed the rigorous testing requirements for human consumption, researchers are able to circumvent a lot of the costly and time-consuming parts of drug development, speeding up the time to clinical trials significantly. Mebendazole has already been the focus of several preclinical and clinical trials, including as a treatment for lung cancer, but it has been also found to be potentially beneficial for other cancers, including glioblastoma, the most common and aggressive form of primary brain cancer.
In a serendipitous turn of events, Gregory Riggins of Johns Hopkins and his team at the Brain Cancer Biology and Therapy Research Laboratory discovered that pinworm-infected mice, which were treated with mebendazole, did not develop appreciable brain tumors, even though the researchers had implanted brain cancer cells weeks before. In subsequent experiments, his team demonstrated that administration of mebendazole prevented tumor proliferation and improved survival times in mice by an average of 63 percent. Currently, mebendazole is part of a phase I clinical trial for patients with newly diagnosed, high-grade glioma and glioblastoma.
Similarly, the anti-malarial compound chloroquine showed surprising properties in combating cancer and tumor growth in a series of experiments led by a group at the University of Kentucky. In a metastatic cancer mouse model, chloroquine led to the production of a specific tumor suppressor protein called Par-4. Par-4 plays a key role in inhibiting tumor cell proliferation, especially in tumor cells that lack p53, which is a well-studied, important tumor suppressor that is commonly inactive in cancerous cells, allowing growth to occur uncontrolled. Tumor cells missing p53 are often refractory to treatment, but compounds that increase production of other tumor suppressors can often compensate for p53 deficiencies and control cancerous growth, leading to hope that chloroquine as a repurposed drug could be promising for treating such cancers.
Both highlighted drugs still need to pass a rigorous battery of studies and clinical trials, and more in-depth research regarding the mechanism by which each combats cancer needs to be done. However, with pre-existing FDA-approved drugs potentially serving double duty as powerful oncologic therapies, cancer patients may soon have more options at hand for improved health and quality of life.
References:
Repurposing an Antiparasite Drug to Fight Glioblastoma
A Pinworm Medication Is Being Tested As A Potential Anti-Cancer Drug
Chloroquine-Inducible Par-4 Secretion Is Essential for Tumor Cell Apoptosis and Inhibition of Metastasis
New Study Shows Promise for Repurposing Anti-Malarial Drug for Cancer Treatment
Antiparasitic mebendazole shows survival benefit in 2 preclinical models of glioblastoma multiforme
Tackling the Bottlenecks in the Drug Development Pipeline
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