A benzimidazole antiparasitic drug used to treat parasitic infections in animals has been reported to be effective in some cancer patients, but the evidence supporting this claim is anecdotal and doesn’t have the backing of randomized clinical trials. Despite this, some cancer patients continue to self-administer the drug because they’ve heard reports that it can cure cancer. Researchers believe that fenbendazole could be an alternative or complementary therapy to conventional treatments for many cancers.
Fenbendazole, marketed as Albenza or Vermox, is used to treat gastrointestinal parasites like pinworms, giardiasis, roundworms and hookworms in a number of animal species. It has also been shown to have anticancer properties, but these aren’t well understood. It’s believed that fenbendazole works by inhibiting the formation of tubulin, a polymer that makes up microtubules. Tubulin is an important component of the cell, acting as both a skeleton and a highway for transport.
It’s thought that fenbendazole stops tubulin polymerization by binding to it, and then prevents the formation of new microtubules. This causes the skeleton of the cell to collapse, which kills the cells. A similar effect was observed in mice with pancreatic cancer that were given mebendazole, another form of the drug. This led the scientists to test if fenbendazole could have the same effect on human cancer cells.
In the study, they used 5-FU-sensitive and -resistant colorectal cancer (SNU-C5 and SNU-C5/5-FUR) cells to determine how fenbendazole affected their growth. They found that fenbendazole caused cell cycle arrest and apoptosis, both in the p53-dependent and -independent pathways, in both cells. It also increased the expression of p21 and decreased mutant p53 in p53-mutant SNU-C5 cells. It activated autophagy, ferroptosis and necroptosis in both p53-sensitive and -mutant SNU-C5 cells.
They also performed experiments in mouse models with a variety of different cancers and found that fenbendazole worked in the same way against them as it did in the colon cancer cells. The drug reduced tumor size and delayed recurrence of the cancers, even when the mice were exposed to other drugs that normally suppress tumors.
The researchers say that the results of their studies should encourage further research into fenbendazole’s effects on humans. However, they emphasize that there isn’t enough evidence from randomized clinical trials to show that fenbendazole can cure cancer in people. They also note that it’s possible that the cancer patient who anecdotally claimed to have cured her of her cancer was receiving other conventional cancer treatments at the same time and that the remission she experienced may be a combination effect rather than due solely to fenbendazole.
Authors Tara Williamson, Michelle Carvalho de Abreu, Dimitri G. Trembath, Cory Brayton, Thais Biude Mendes and Paulo Pimentel de Assumpcao have financial interests in Benizole Therapeutics, which is developing mebendazole. They disclose this in the paper.
This work was supported by the Virginia and D.K Ludwig Fund for Cancer Research. Drs. Riggins and Williamson have intellectual property on mebendazole, and they report ownership and conflict of interest policies. fenbendazole for cancer