Fenben, also known as fenbendazole, is an animal dewormer (anthelmintic) in the benzimidazole carbamate family. It has been in use as an anthelmintic for nearly 50 years. It has been shown to have some anti-cancer properties in lab testing, but turning these results into a human drug is a long road. A few anthelmintic drugs in the benzimidazole family are currently being studied as cancer treatments but it’s too early to tell if any will succeed.
Unlike many anticancer drugs, fenbendazole is not toxic to normal cells at doses up to the maximum recommended human daily allowance. In addition, a long history of safety in humans and animals has allowed the drug to be used to treat many different conditions. Nevertheless, despite its low toxicity, fenbendazole is an insufficient treatment for most tumors. It is also unable to overcome the barriers that separate healthy tissues from cancerous ones, including the blood-brain barrier in brain tumors.
However, a new study published in Nature Communications suggests that combining the dewormer with other treatments can increase its effectiveness. In this study, the researchers found that combining fenbendazole with rapamycin (RAPA) significantly decreased cancer cell viability in vitro and in vivo. RAPA is a kinase inhibitor that is known to target and inhibit tumor growth.
In the in vitro cytotoxicity test, both free fenbendazole and FEN-RAPA-loaded mPEG-b-PCL micelles showed comparable efficacy against A549 cells. However, in the in vivo biodistribution and pharmacokinetic studies, micelles exhibited greater accumulation and drug release kinetics than solution formulations. In addition, the mPEG-b-PCL particles were consistent in size and possessed high encapsulation efficiency and drug loading capacity.
The researchers then tested the effect of fenbendazole and RAPA on EMT6 cell viability in the x-ray-irradiated tumor model. Tumor growth was measured and compared between controls, irradiated tumors treated with three doses of fenbendazole alone or irradiated tumors treated with fenbendazole plus 10 Gy of radiation. The results showed that the growth curve of unirradiated tumors was not altered by either treatment, and in contrast, irradiation combined with three fenbendazole treatments was able to decrease tumor viability to below the detection limit. fenben