Fenbendazole is a benzimidazole anthelmintic drug widely used to treat parasitic infections including pinworms (Giardia lamblia), giardiasis, roundworms, hookworms, and Taenia solium. Some studies using cell cultures and animals have shown that fenbendazole can inhibit cancer growth by blocking microtubule polymerization. However, there is no evidence from randomized clinical trials that fenbendazole can cure cancer in human patients.

An 80-year-old female patient with advanced nonsmall cell lung cancer (NSCLC) who was receiving pembrolizumab monotherapy developed severe liver injury 9 months later. It was discovered that she had started self-administration of fenbendazole, solely based on social media reports suggesting that it could help cure cancer. The patient was able to discontinue the fenbendazole and resume pembrolizumab therapy, and her liver injury improved spontaneously.

In vitro cytotoxicity assays revealed that both free fenbendazole (FEN) and FEN-loaded mPEG-b-PCL micelles were able to effectively inhibit cancer cell proliferation. The micelles showed better cell penetration compared to free FEN, but they also exhibited less potent cytotoxic effects than free FEN at the same concentrations.

To evaluate the in vivo efficacy of FZ, we treated athymic nude mice with A549 xenografts and administered either free FZ or FEN-loaded mPEG-b-PCL micellar micelles. After 2 wk of treatment, colony formation was assessed by clonogenic assay. Both FEN and the micelles effectively inhibited tumor growth and induced p53 at significantly high levels compared to control mice. In addition, a morphologic examination of tumors showed that the mice with FZ-treated tumors had significantly smaller tumors and lower vascularity than those with control tumors. fenben for cancer