Fenbendazole (also known as mebendazole) is an anti-parasitic drug used to treat worm infections including pinworms, whipworms, hookworms and giardiasis in humans. It has a very good track record of safety in human use for long periods. It was also discovered to have powerful cancer killing activity in lab experiments. It works by interfering with the formation of microtubules, a protein scaffold in cells that provides structure and shape. Cells establish their shape and movement through the cytoskeleton, which is composed of polymers (microtubules) made up of proteins such as tubulin. Microtubules are involved in many important cellular processes, such as cell cycle progression (i.e., separating chromosomes during cell division). Drugs that interfere with tubulin polymerization can have similar effects to cytotoxic anticancer drugs such as vinblastine and vinorelbine.
The anecdotal experience of a man named Joe Tippens who claimed his lung cancer went into remission after he began taking fenbendazole as an anthelmintic on his veterinarian’s recommendation has gained traction in social media. However, there is insufficient evidence that fenbendazole cures cancer in humans.
Using drugs developed for one condition to treat another is called drug repurposing, and it’s becoming increasingly popular as the cost of developing “new” drugs increases and time to get them through clinical trials becomes longer. It is estimated that it costs between $1 – $2.5 billion to bring a new drug from discovery to approval by the FDA. It is much less expensive to test existing drugs to see if they are effective against other conditions, and this is how fenbendazole became an anti-cancer drug. fenbendazole cancer treatment