Is Fenbendazole For Humans Cancer Safe?

A dog dewormer called fenbendazole has been promoted by some as a cancer cure, but there's no proof it's effective and the U.S. Food and Drug Administration warns people against taking it for this purpose. Health Feedback reports that Joe Tippens, an Oklahoma man with small-cell lung cancer who was told he had a short time to live, claimed he was cured by the medication. He said he had used fenbendazole after it was recommended by his veterinarian. Tippens was interviewed by a local news station, and his story gained worldwide attention. The National Cancer Institute and the FDA urge people not to take any medication that hasn't been proven safe and effective in clinical trials, which precede regulatory drug approvals.

The anthelmintic medication fenbendazole, which is used to treat parasitic infections in dogs and cats, destabilizes microtubules and interferes with cell division. During mitosis, chromosomes are lined up in metaphase before being separated evenly at anaphase during the final stage of cell division (mitosis). The separation is aided by structures made of tubulin. Drugs that block tubulin polymerization interfere with the process and may cause mitotic catastrophe, which is when chromosomes are not properly separated and result in abnormal cell death.

In a recent study, researchers found that fenbendazole caused different types of cell death in colorectal cancer cells resistant to 5-fluorouracil (FU) chemotherapy. The research team analyzed the anticancer effects of fenbendazole on FU-sensitive and -resistant SNU-C5 and SNU-C5/5-FUR colon cancer cells using flow cytometry to measure cell viability, Western blotting, and other assays. The results showed that fenbendazole increased G2/M phase arrest and apoptosis in the cells, but also induced ferroptosis, which is characterized by iron accumulation involving the oxidation of proteins, including the mitochondrial GSH peroxidase 1 (GPX1) and cysteine uptake protein SLC7A11.

A team of scientists from Japan and France developed a fenbendazole/rapamycin-loaded mPEG-b-PCL micelle with an average particle size of 37.2 +- 1.10 nm, a zeta potential of -0.007 +- 0.09 mV, and a polydispersity index of 0.20 +- 0.02. The micellar formulation was tested for its ability to encapsulate fenbendazole and rapamycin and to release both drugs. In a clonogenic assay, the M-FR micelle was 6-9 times more effective than free fenbendazole and a 3-fold more potent than rapamycin alone.

However, owing to the low solubility of fenbendazole, the ability to encapsulate high doses of this drug in micelles is still limited. To address this issue, the researchers designed a novel fenbendazole/rapamycin conjugate with a hydrophobic cyclodextrin linker that allows the peptide drug to dissolve more easily in water. In addition to the improved permeability, this linker significantly enhanced the conjugate's anticancer efficacy compared with free fenbendazole and the rapamycin-only M-FR micelle in a clonogenic assay in HeyA8 cells. In vitro drug-release studies also revealed that M-FR releases fenbendazole and rat rapamycin at slower rates than free fenbendazole or the fenbendazole/rapamycin-only micelle, M-R. This is due to the physicochemical properties of the micelle, including its lower polarity and smaller size.fenbendazole for humans cancer