Fenbendazole is a benzimidazole carbamate drug with broad-spectrum antiparasitic activity against ascarids, whipworms, hookworms, and a single species of tapeworm (Taenia pisiformis) in humans and animals. It acts by inhibiting microtubule polymerization, reducing glycogen stores, and blocking ATP formation in the adult stages of susceptible parasites. The anthelmintic properties of fenbendazole make it a common treatment for tapeworm infections in both pets and livestock.
Recently, several reports have shown that fenbendazole has antitumor effects in various cell types and cancer models. These results have led to the repurposing of anthelmintic drugs such as albendazole, mebendazole, and fenbendazole to treat cancer. However, there have been no clinical trials in patients that validate the efficacy of this approach. The anecdotal report of Tippens may be an exception but it remains an unproven and potentially dangerous treatment.
A female patient with advanced non-small cell lung cancer had increased CEA levels despite receiving pembrolizumab monotherapy. She informed us that she had recently self-administered oral fenbendazole, an anthelmintic used to treat tapeworms, based on information on social media websites claiming that it is effective against cancer. Upon reevaluation, she had no tumor regression.
In an attempt to identify the cause of her lack of response, we analyzed the viability of wild-type and 5-fluorouracil-resistant SNU-C5 colorectal cancer cells after fenbendazole treatment. Apoptosis was analyzed by flow cytometry and Western blotting. The results showed that fenbendazole-treated SNU-C5/5-FUR cells had reduced autophagy and ferroptosis, but enhanced GPX4-mediated oxidative stress-augmented apoptosis.
GPX4 is a mitochondrial protein that functions as a sensor of intracellular ROS and triggers oxidative stress-augmented apoptosis in a p53-independent manner. The results from this study indicate that fenbendazole may be a promising alternative therapy to overcome resistance to chemotherapeutic agents in cancers with a KRAS mutation.
As with all medications, fenbendazole can cause side effects. If you notice any signs of an allergic reaction to fenbendazole such as facial swelling, itchiness, hives, diarrhea, or shock, seek immediate veterinary care. At regular doses, fenbendazole does not typically cause these symptoms. Symptoms of an overdose include severe stomach pain, coma, and death. Do not exceed the recommended dosage of fenbendazole or give two doses at the same time. Always store fenbendazole granules in a sealed container at room temperature and protected from sunlight. If you have questions about fenbendazole or other medications, consult your veterinarian. fenbendazole for humans