In the lab (in vitro) fenben (FZ) can kill cancer cells and reduce tumor growth. But can it cure cancer? That’s the question in the spotlight after a viral Facebook post by Joe Tippens went viral. The nonprofit Cancer Research UK told PolitiFact that there’s no evidence that fenben can cure cancer, and that the drug hasn’t gone through clinical trials to see if it’s safe or effective for treating patients.

The antiparasitic drug fenben has been shown to have anticancer effects in animal and human cells, including inhibiting cell growth, blocking the formation of new blood vessels, and killing cancer cells. It’s also known to activate necroptosis in colorectal cancer cells, but whether that could prevent cancer recurrence and metastasis isn’t clear.

Benzimidazole compounds, such as fenben, target the mitochondria of cancer cells and induce mitophagy, which destroys defective or abnormal mitochondria. The enzyme AMP-activated protein kinase (AMPK) regulates autophagy, and phosphorylation of its downstream target mLKL is required for necroptosis in CRC cells. In vivo, fenbendazole reduces the volume of irradiated tumors in mice, but not the number of lung metastases that occur after treatment.

We tested whether fenbendazole could reduce the growth of A549 xenografts in nu/nu mice by administering oral doses of the drug every other day, starting when tumors were 2-4 mm in diameter. FZ significantly reduced tumor growth in both unirradiated and irradiated tumors, measured by soft agar colony counts. Hemoglobin content, a measure of tumor vascularity, was also reduced in FZ-treated mice (Fig. 9d).fenben cancer treatment