Fenbendazole is a benzimidazole anthelmintic drug that’s been used to treat parasitic worm infections in humans and animals. It’s also been used in a handful of studies to show that it can slow down or kill cancer cells in lab dishes and in animals, and that it might help other drugs work better against some kinds of cancers.
But in spite of those promising pre-clinical findings, fenbendazole hasn’t been tested in human clinical trials. It’s not a cancer treatment and it can’t cure cancer, even if it does help some patients in anecdotal cases like Tippens’. As a specialist cancer information nurse for Cancer Research UK tells Full Fact, “There is insufficient evidence that fenbendazole can cure cancer – it hasn’t gone through any clinical trials to find out if it’s safe or effective.”
Social media sites have been useful for disseminating medical information; however, the ability of nonmedical individuals to select and filter complex medical information may contribute to the spread of unproven medical facts. A patient with advanced nonsmall cell lung cancer (NSCLC) received pembrolizumab monotherapy and experienced severe liver injury 9 months later. After interviewing the patient, her family revealed that she had obtained information on fenbendazole from social media sources, which suggested it was effective against NSCLC. She then purchased and started to orally self-administer fenbendazole, which is marketed as an antiparasitic drug for dogs.
The drug interferes with the formation of microtubules, which are the protein scaffolding that gives cells their shape and structure. Textbook depictions of cells often look like a bag of various cellular components floating in amorphous bags of liquid, but that’s far from the truth. Microtubules form a rigid framework that allows other cellular components to assemble and disassemble, and it’s through this system that cells establish their shape and move about the body.
Using immunofluorescence, the researchers found that fenbendazole inhibited NSCLC tumour growth and cell proliferation in animal models. The team then formulated a micelle containing fenbendazole and the chemotherapy drug rapamycin, which was delivered to tumours in mice. The resulting drug combination significantly decreased tumour growth and rescued animals from apoptosis, which was not seen in mice given fenbendazole alone.
Developing new medicines takes many years and can cost millions of dollars. Repurposing existing drugs that already have been approved for use in other conditions can save time and money. The researchers say their fenbendazole/rapamycin conjugate (M-FR) has an average particle size of 37.2 +- 1.10 nm, a zeta potential of – 0.07 +- 0.09 mV, and a polydispersity index of 0.2 0.03. The drug release profile was characterized in vitro and the micelle exhibited a high level of encapsulation efficiency with low degradation. The conjugate was well tolerated by human cells and exhibited less toxicity in animal models than free fenbendazole. A Phase I study in healthy volunteers is planned. The authors suggest that this approach could potentially be extended to other drug combinations. The fenbendazole/rapamycin-loaded mPEG-b-PCL micelle can be easily produced and is readily soluble in water for aqueous delivery to tumours. fenbendazole for humans cancer