Recently, posts on social media have gained traction that claim that a dog deworming medication called fenben is also effective against cancer in humans (see examples here and here on Facebook or here on TikTok). This is based on the anecdotal story of a man named Joe Tippens who claims to be in remission from his lung cancer after using fenben on a vet’s recommendation.
Despite these wildly popular online reports, there’s still not enough evidence to support that fenben can cure cancer in people or animals. However, fenben has been found to have some interesting effects on human cancer cells in lab experiments. This has led to a new trend in modern medicine: the repurposing of drugs that were originally meant for other purposes and testing their efficacy against human cancer.
For example, a number of antibacterial drugs have been repurposed as cancer treatments after discovering that they had potent anti-tumor effects in laboratory experiments. Among these are paclitaxel and vincristine, which have been shown to be effective against various tumor types in randomized clinical trials.
The anthelmintic drug fenben, which is used to treat parasites and worms in dogs, cats, horses, cattle, and other livestock, was also recently repurposed after it was discovered that it had anti-cancer effects in mice experiments. Its anti-tumor effects are due to its microtubule-destabilizing and p53 stabilizing properties. This led researchers to conduct additional tests on fenben’s effectiveness against cancer cells, including its ability to inhibit glucose uptake in human cancer cells.
Cancer cells use a large amount of glucose to fuel their rapid growth and proliferation, requiring them to consume multiple times as much glucose as normal cells. This disparity in energy metabolism makes them particularly susceptible to inhibition of glucose uptake by pharmacological agents. Fenben, which is a member of the benzimidazole class of antiparasitic medications, showed promising cytotoxicity against human cancer cells by inhibiting glucose uptake in a cell culture assay.
Results from the study demonstrated that high doses of fenben significantly reduced the survival of EMT6 cancer cells. This effect was observed both in a standard colony formation assay and a more rigorous survival assay that measured the time it takes for tumors to grow from their original volume to four times that size. Additionally, fenbendazole caused a significant increase in the concentration of glucose in culture supernatants, which was consistent with its cytotoxic effects.
The researchers conclude that fenbendazole’s anti-tumor effects may be mediated by moderate microtubule disruption, p53 stabilization, and interference with glucose uptake in cancer cells. Because of its minimal risk to humans, fenbendazole is likely to pose an attractive alternative therapy for the treatment of cancer. This is especially true given that other cancer drugs with similar effects, such as paclitaxel and vincristine, have been successfully tested in randomized clinical trials on fenben for humans