Fenbendazole is a broad spectrum benzimidazole anthelmintic used to treat gastrointestinal parasites in dogs, cats and horses (including giardia, roundworms, hookworms, whipworms and the tapeworm genus Taenia). It is also useful in preventing pulmonary helminths in some cats.

Researchers have discovered that fenbendazole, which is widely used as an anti-parasitic drug in animals, can also be used to treat cancer in humans. The drug inhibits cellular proliferation by causing a disruption of microtubules in the cell, and this effect is reversible. In one study, researchers treated human non-small-cell lung cancer cells with fenbendazole and observed that this caused the tumours to lose their adherence to the surrounding cell membrane.

Another study tested the effectiveness of fenbendazole in a number of different cancer cells, and found that it caused a partial alteration in the structure of the mitotic spindle and inhibited cell division. Additionally, they found that fenbendazole prevented the formation of a cyclin-CDK1 complex which normally promotes progression through metaphase to anaphase.

A final experiment tested the effects of fenbendazole on the growth of two CRC tumor cell lines in mice. The mice were injected with either untreated tumors or tumors that had been irradiated, and then treated three times daily with fenbendazole. The time it took for each tumor to grow from its initial volume to four times that volume was measured and compared between groups. Fenbendazole was found to significantly inhibit the growth of both unirradiated and irradiated tumors. fenbendazole capsules