While lab experiments can look promising, we won’t know if fenbendazole actually works or is safe until it is tested in human patients. A specialist cancer information nurse at Cancer Research UK tells Full Fact that there isn’t enough evidence to suggest fenbendazole, a broad-spectrum anthelminthic drug used to treat parasites in dogs, would help people with cancer.
Researchers found that fenbendazole could kill cells by interfering with the normal growth of microtubules, which provide structure to all cells. This makes cancer cells lose their shape and ability to move, causing them to die off. It also has the potential to starve cancer cells by blocking their glucose uptake, as it interferes with GLUT4’s linear movement through the microtubules, reducing insulin-fueled sugar absorption.
The results also showed that fenbendazole was less toxic to aerobic EMT6 cells than nonaerobically treated cultures, even at concentrations approaching the limit of solubility. Hypoxia increased the toxicity of 2-h treatments, however, suggesting that oxygen may be required for optimal fenbendazole efficacy (8, 9).
In addition to reducing tumor viability, fenbendazole also activated G2/M arrest and apoptosis in 5-FU-sensitive colorectal cancer cells (SNU-C5 and SNU-C5/5-FUR). Benzimidazoles bind to tubulin and disrupt its microtubule equilibrium, making it difficult for microtubules to polymerize. Cancer cells with wild-type p53 showed higher sensitivity to fenbendazole than p53 mutants, and the drug induced both p21 and p53-mediated apoptosis as well as autophagy and ferroptosis in these cells. (10) fenbendazole powder