Researchers are investigating whether anthelmintic drugs—medications that are used to treat parasites in animals—could also be effective cancer treatments for humans. The findings of an animal study are promising but the long journey from a scientific paper to a drug approved by Health Canada is ahead.

In the study, published on July 6 in Oncotarget, Gregory Riggins and his colleagues found that high doses of the benzimidazole medication mebendazole—which is commonly used to fight roundworms, hookworms and other parasitic infections—inhibited the growth of paclitaxel-resistant tumors. The drug works by cutting off the cancer cells’ supply of nutrients. It does so by targeting the protein tubulin, which is both a micro-skeleton of the inner cell and a highway for transporting proteins. The drug gets into the tubulin and collapses it, starving the cell. The finding supports previous reports that benzimidazole drugs may be useful in treating cancer.

Riggins and his team next tested the benzimidazole mebendazole against two colon cancer (CRC) cell lines—SNU-C5 and SNU-C5/5-FUR. Mebendazole inhibited the proliferation of both CRC cell lines. This was due to a combination of mechanisms: repression of autophagy, ferroptosis-augmented apoptosis and reduction of caspase-8 activation in 5-fluorouracil-resistant SNU-C5 cells.

The team then injected tumor-bearing mice with three daily i.p. injections of mebendazole or vehicle and exposed them to 10 Gy of x-rays. The growth of the tumors was not affected by fenbendazole alone but, when combined with x-rays, it significantly inhibited their development. fenbendazole stage 4 cancer