Fenbendazole is an animal anthelmintic, effective at high doses against hookworm (Necator americanus), as well as against roundworm and whipworm. It also has a long track record of safety in human use.
In a clonogenic assay, 24-h incubation with high doses of fenbendazole reduced the viability of EMT6 cells. This was a combination of cytostatic and cytotoxic effects, with a rapid decrease in cell numbers, as well as a reduction in the number of colonies formed (Table 1).
Our experiments demonstrated that fenbendazole is effective as an anticancer agent in vitro and in vivo, at doses normally used in humans for the treatment of helminth infections. The effect of the drug is mediated by its ability to inhibit microtubule polymerization, and to disrupt the polarity of tubulin in mammalian cells and parasitic organisms.
In addition to its utility as an antihelmintic drug, fenbendazole is capable of inducing cellular cytotoxicity at relatively low concentrations, and has the potential to act synergistically with hypoxia-selective nitroheterocyclic chemotherapeutic agents such as the taxanes and vinca alkaloids. The drug is poorly absorbed from the gut and rapidly converts to the active compounds, fenbendazole sulfone and oxifendazole (13, 14).
A 52-year-old woman with metastatic non-small cell lung cancer (NSCLC) presented with elevated CEA levels and was referred for evaluation of possible tumor shrinkage by her physician. The patient reported that she had been self-administering oral fenbendazole since early July 2019, based on information she read on social media websites claiming that the medication is effective against cancer. fenbendazole stage 4 cancer