Fenbendazole is a broad-spectrum anthelmintic in the benzimidazole family of medicines. It is used in humans and animals to treat parasites such as pinworms (Enterobius vermicularis). It is also approved by the FDA for use as an anti-parasitic in horses. Fenbendazole is a well tolerated drug with a wide safety margin and has been shown to be safe for dogs and cats. Its low degree of toxicity makes it an excellent candidate for tumor treatment regimens, especially when combined with other treatments such as surgery, radiation, and chemotherapy.
In a recent study, researchers established artificially derived lymphoma xenografts in SCID mice and found that fenbendazole inhibited tumor growth. The researchers wanted to know if the effect could be enhanced by combining it with other treatments such as surgery, radiation, or chemotherapy. They found that the synergy between fenbendazole and these other treatments is more pronounced than either treatment alone.
The mice in the experiment were supplemented with diets containing a control group that received no dietary supplemental vitamins or with a treatment group that was given both fenbendazole and various cancer-fighting vitamins. The dietary supplements were administered for 2 wk prior to subcutaneous flank implantation of 3 x 107 lymphoma cells. Tumor size was measured with a caliper at 4-d intervals until the largest tumor reached a calculated volume of 1500 mm3. The mice treated with vitamins and fenbendazole had significantly smaller tumors than did those treated with vitamins alone. In addition, the fenbendazole and vitamin groups together exhibited an even greater inhibition of tumor growth than did the vitamins and fenbendazole alone.
To determine if fenbendazole is radiosensitizing, cultures of EMT6 cells were exposed to radiation in the presence and absence of fenbendazole. Radiation dose-response curves were determined for both aerobic and hypoxic cultures. Fenbendazole did not alter the radiation response of aerobic cultures and exhibited moderate cytotoxicity in hypoxic cultured cells.
Upon the completion of the study, complete blood counts were obtained from the control and test groups. Initial complete blood count results were typical of SCID mice and showed a paucity of white cells. However, at the time of study termination, both the fenbendazole and the vitamins + fenbendazole groups had significantly lower total white cell and neutrophil responses than did the controls. These findings suggest that fenbendazole can significantly reduce the immune response to tumors in immunocompetent mice, thus allowing other therapies to be more effective in treating them. Currently, this is an active area of research for scientists trying to develop new cancer treatment methods. If this proves to be true in human trials, it will allow many more patients to receive better and more effective treatment options for their cancer. It may also lead to the development of improved veterinary anti-parasitic drugs. This is important because it is estimated that as many as 10% of all pets in the United States are infected with the pinworm Enterobius vermicularis, which can be treated with a simple oral medication. sanare lab fenbendazole