Fenbendazole (also known as melbendazole) is an antiparasitic medication used to treat parasitic worm infections in animals. It has been repurposed to be a human cancer treatment, and it appears to work by stopping the proper growth of microtubules in tumor cells. Microtubules are part of all living things and give structure to cells. Cancers often grow by ignoring the normal control mechanisms that keep them from growing too much, but this anthelmintic drug is able to inhibit the growth of tubulin, which microtubules use to form their structures.
Besides inhibiting microtubule growth, fenbendazole has also been shown to cause necroptosis in colorectal cancer cells, which is the death of cancerous cells. It accomplishes this by blocking the activity of a protein that normally keeps insulin-fueled sugar absorption from occurring inside the cell. The scientists also found that fenbendazole inhibits the appearance of the glucose transporter isoform 4’s intracellular movement through microtubules, further cutting off the supply of sugar to the cancerous cells.
The team injected EMT6 tumors with three daily injections of fenbendazole or an identical control. The researchers then measured the size of the tumors and compared their appearance and behavior to the weight of the mice. The results showed that fenbendazole alone was not effective in slowing the growth of tumors, but it was effective when combined with radiation therapy.
The authors of the study are unsure why this anthelmintic medication has not been approved to treat humans, but they believe that it could be due to lack of adequate pre-clinical animal data. They note that fenbendazole is very safe to be given to animals at dosages several times greater than the FDA-approved human dose, and they suggest that this evidence might be sufficient for human trials of the drug’s efficacy against cancer. fenbendazole for humans