A benzimidazole, fenbendazole is an over-the-counter antiparasitic medication used to treat parasitic infections (e.g. pinworms, giardiasis, roundworms, hookworms and pulmonary paragonimiasis) in many animal species including dogs, cats, rats, rabbits, cattle and horses. It’s also used to treat parasites that cause gastrointestinal upset in humans, including stomach ulcers.
The pharmacological properties of fenbendazole are derived from its ability to interfere with the polymerization process of tubulin, the cytoskeleton structure that gives shape and support to cells. Interestingly, tubulin is also affected by the cytotoxic properties of many chemotherapeutic drugs including vinca alkaloids and taxanes.
In an early study, researchers treated human non-small cell lung cancer cells with fenbendazole and found that it partially disrupted the microtubule network around the nucleus and induced cell death. In addition, the drug was found to reduce tumour growth and metastasis in genetically engineered mice that developed pancreatic cancer.
Other studies have shown that fenbendazole has in vitro and in vivo antitumor effects. For example, in SNU-C5 colorectal cancer cells with a KRAS mutation, fenbendazole caused apoptosis by inhibiting the cell cycle and causing apoptotic pathways to activate such as mitochondrial injury and caspase-3-dependent apoptosis. It also suppressed the RAS-related signaling pathway expression.
Another study found that fenbendazole was effective in treating colorectal cancer with wild type p53 tumour suppressor genes. When researchers fed fenbendazole to athymic nu/nu mice with SNU-C5 colorectal carcinoma, they observed that the drug reduced tumor size and weight.
However, there’s no evidence that fenbendazole can cure cancer in people. Specialist cancer information nurse at Cancer Research UK, Caroline Geraghty told Full Fact that although fenbendazole has been shown to work in studies of cells and animal models, it’s not been proven to be a cancer treatment in humans and hasn’t been through any clinical trials to find out whether it’s safe and works in real patients.
Tippens himself has been clear that his remission was not due solely to fenbendazole. He says that he received other conventional cancer treatments during his remission, which aren’t being accounted for and which may have helped him overcome the recurrence of his kidney cancer. He’s also been open about the fact that his remission was anecdotal and that he only began taking fenbendazole after seeing social media posts claiming that it could kill cancer. As a result, we can’t reliably attribute his remission to fenbendazole alone. You can read more about his story here and here. If you want to add fenbendazole to your treatment, speak with your doctor before doing so. They will be able to discuss the risks and benefits of this treatment with you. They’ll also be able to recommend other treatment options that are right for you. fenbendazole for cancer