Benzimidazole anthelmintic agents have been repurposed to overcome cancers resistant to conventional therapies. This study was designed to determine if fenbendazole could enhance the anti-tumor effects of radiation in 5-fluorouracil-resistant colorectal cancer cells.
The growth of tumors was monitored over time. The results show that fenbendazole alone did not affect the growth of unirradiated tumors, but fenbendazole and radiation synergistically inhibited tumor growth.
Inhibits Glucose Uptake
Fenbendazole is an anthelmintic used to treat parasites in dogs. It’s a powerful drug that interferes with the formation of microtubules, which provide structure to all cells. While cell structure is portrayed in textbooks as an amorphous bag of floating cellular parts, all cells actually have a highly dynamic, protein-based scaffolding that gives them shape and structure. This scaffolding is composed of a network of microtubules, and it’s what cancer cells use to reorganize themselves into structures that can move through narrow spaces or change their shape to move more easily from one place to another within the body.
Research in laboratory dishes and mice has shown that fenbendazole can suppress the growth of some cancer cells. But researchers haven’t yet conducted clinical trials in people to see whether it can also be an effective cancer treatment. Specialist cancer information nurses at Cancer Research UK told Full Fact that there’s insufficient evidence to show that fenbendazole can cure cancer, or is even safe for humans.
Induces Apoptosis
A cell’s shape and structure are determined by a protein scaffolding called the cytoskeleton. This is made of microtubules, which are in turn made from a protein called tubulin. When a cancer cell grows, it needs to expand its cytoskeleton so that it can move and maintain its shape. Fenbendazole interferes with the formation of these proteins.
When researchers treated human ’non-small cell lung cancer cells’ with fenbendazole, they found that the drug caused partial alteration of the microtubule network. The drugs also induced apoptosis in the cancer cells.
Researchers have observed similar results in mice. For example, a 2021 press release by Johns Hopkins Medicine reported that the antiparasitic medication mebendazole could slow the progression of pancreatic cancer in genetically engineered mouse models. However, this anecdotal experience isn’t enough evidence to warrant fenbendazole becoming an alternative treatment for cancer in humans. In order for this to happen, randomized controlled trials involving large numbers of patients would need to be performed first.
Inhibits Mitochondrial Damage
Researchers discovered that fenbendazole and other drugs in its class inhibit tumor growth in cell cultures and mice. They found that the drug stops the proper growth of microtubules, a structure that provides support to all cells in the body and helps separate chromosomes during cell division (mitosis).
These findings were published in the journal Scientific Reports. They showed that fenbendazole causes cancer cells to die by partially altering the microtubule network and by activating multiple cell death pathways. They also found that fenbendazole can inhibit mitochondrial damage in colorectal cancer cells and that its effect does not require the tumor suppressor p53.
The scientists tested the drugs in animal models, and a mouse with colon cancer that was treated with the antiparasitic compound every other day for 12 days experienced a significant reduction in tumor size and weight. Mebendazole, another benzimidazole drug, also slowed tumor growth in the same model. The team plans to further study the effects of fenbendazole and other compounds in its class to determine if they are suitable for use as a cancer treatment.
Induces Cell Death
The anti-parasitic drug mebendazole works against parasitic infections by collapsing the micro-skeleton of the parasite, starving it to death. Research on human cancer cells suggests that fenbendazole may work in a similar way.
In the lab, fenbendazole interferes with the formation of microtubules, a protein scaffold that gives cells their shape and structure. The drug also stops the cancer cells from releasing the cyclin B1 that triggers mitosis.
Researchers found that fenbendazole causes apoptosis in human ‘non-small cell lung cancer’ cells, and that the effect is increased when the cells have wild type p53 tumour suppressor genes. The drug also inhibits cancer cell growth in mice, with a reduction in the size and weight of tumours.
But it’s important to remember that the studies in cells and mice can look promising but don’t prove anything. And even if fenbendazole does reduce cancer cell growth in humans, there’s no evidence it would have any impact on cancer itself. The expert cancer information nurse at Cancer Research UK told Full Fact that there isn’t enough evidence that fenbendazole cures cancer, but it may help with symptoms.