Originally written 2/25/2019
Before jumping on the fenbendazole (FZ) bandwagon, here’s an important update to the 2019 blog below. True, this de-worming agent for dogs has been showing anti-tumor properties in lab and mouse testing against cell lines in prostate cancer (PCa)[i], ovarian cancer[ii], breast cancer[iii] and others. Thus far, however, getting the drug into cancer cells in humans has been an insurmountable challenge.
According to one paper, “Qualitative and quantitative analysis of formulated fenbendazole indicates some formulation issues that hinder distribution.”[iv] When formulated for greater bioavailability (uptake by cells), fenbendazole showed preferential cell death towards metastatic PCa cells, prolonging survival in mice with implanted metastatic PCa cell lines[v].
Although initial research indeed shows promise for repurposing fenbendazole or similar compounds as primary or adjunct use against PCa and other cancers, no one has yet found a way to apply it selectively to tumors in human patients for testing. In fact, to the best of our knowledge, there have been zero clinical trials testing FZ in human cancer patients.
Regardless of individual or anecdotal claims you may find on social media, the FDA has not approved use of FZ against cancer. If you or a loved one has PCa (or any other cancer) and has heard tales about “cure” due to FZ, our best advice is to have an open and honest consultation with an oncologist. Never experiment on yourself with this or any other drug!
If a dog is a human’s best friend, a drug for Fido may be cancer’s worst enemy. Remarkable stories about cures for cancer are coming from many cancer patients—some deemed incurable—who have taken a drug called fenbendazole (FZ). FZ is used by veterinarians to treat intestinal worms in animals. It is safe and effective for household pets like dogs, cats, and rabbits. It is also safely used with farm animals like cows, horses, and sheep. It is even effective against intestinal worms in fish. In fact, it is so safe that it is available online without prescription. So what does that have to do with cancer in humans?
Background
FZ is part of a class of pharmaceutical called anthelminthic drugs. These drugs get rid of parasites in the gut. Several years ago, a related drug called mebendazole (MBZ) had already gained attention for its antitumor properties. This was discovered almost by accident. MBZ is routinely used to prevent or stop worm infections in laboratory rodents. Investigators noticed that mice in which cancer cells had been implanted failed to develop tumors when they were given MBZ. Further laboratory studies demonstrated that MBZ could kill cancer in cell studies and animal experiments. There were subsequent published reports in which it had boosted radiation or chemotherapy treatments with humans. However, it appeared that MBZ was not equally effective with every person due to uneven absorption.
FZ has a parallel story. Investigators were having the same experience with FZ, but a single individual named Joe Tippens took FZ from the laboratory into the public eye. Joe credits FZ with sending his metastatic lung cancer into complete remission. He made a commitment to tell his story to as many people as possible. To that end, he created a blog called mycancerstory.rocks which documents his journey from death’s doorstep to life without cancer. As it went viral, other individuals began sharing their experience with him. Over time, he collected over 40 stories of individuals with varied cancers like pancreatic cancer, ovarian cancer, colorectal cancer and more—people who reported that FZ had likewise caused their metastatic disease to seemingly evaporate from their bodies.
Joe admits that what he now calls “FenBen protocol” does not work for everyone. the other hand, his own story is something of a medical miracle, and the other accounts he includes are just as dramatic. This raises the question, “Is there science to back this up?”
The science behind FZ
Let’s start the origin of fenbendazole as a treatment for parasites in animals. Merck Animal Health, makers of one FZ-containing product, offers a simple of how FZ deworms horses:
Inside the cells of animals and parasites are structures called microtubules, which are important in a number of cellular processes. When fenbendazole is absorbed by the worm, it interacts with the worm’s microtubules. Fenbendazole works by binding to the beta-tubulin within the microtubules and inhibiting their formation, resulting in disruption of cell division. This potent disruption blocks the parasite’s ability to produce energy, starving the parasite until it dies.
What makes fenbendazole unique is that it is more attracted to parasite beta-tubulin than that of the animal being treated. This means the animal’s cells are not destroyed along with the parasite. This is also the reason the parasite is slowly killed, and why fenbendazole is a safe choice for deworming in so many different situations and for every horse, regardless of age, size or body condition. As well as safe for the environment and many other species.[vi]
In 2018, the journal Scientific Reports published an article by Dogra, et al.[vii] that offers several detailed biochemical and cellular mechanisms by which FZ is fatal to human cancer cells. While some of them have to do with disrupting chemical processes within the cell structure, perhaps the simplest one to understand is that FZ destroys a cancer cell’s ability to obtain nourishment and manufacture the energy to live. It dies off. What is most remarkable is that FZ only has this effect on cancer cells, not healthy cells.
What do we know for certain?
There is more of what we don’t know about FC than what we do know. We don’t know exactly why has an affinity for cancer cells that it does not have for healthy cells. We don’t know why it will work for some people but not for everyone. We don’t know the minimum effective dose or the maximum dangerous dose in humans.
But based on the existing evidence, whether scientific or anecdotal, here is what we can safely say[viii]:
- FZ has demonstrated anticancer effects against non-small cell lung cancer, lymphoma, prostate cancer, and glioblastoma (Joe Tippens’ blog reports other tumor cancers as well)
- in some diseases FZ is more effective than MBZ, possibly due to more even absorption
- using vitamin E along with FZ enhances its effectiveness
- in some cancer patients FZ alone may work, but more likely may be used to boost chemotherapy or radiotherapy
The most important point is that FZ is well worth more study. I study, I mean accumulating patient records in cooperation with physicians so the data can be collected and analyzed and reported. Until we have enough human experience with cancer patients, it will be difficult to achieve consensus on the status of FZ is a true contribution to cancer treatment. It is my hope that patients who decide to take FZ will be honest with their physicians, and that their doctors will be open to working with them and keeping good medical records. This is an exciting time when drugs with one application are being repurposed for other applications will FC be one of those? Time will surely tell.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
References
[i] Chung I, Zhou K, Barrows C, Banyard J et al. Unbiased Phenotype-Based Screen Identifies Therapeutic Agents Selective for Metastatic Prostate Cancer. Front Oncol. 2021 Mar 2;10:594141.
[ii] Chang CS, Ryu JY, Choi JK, Cho YJ et al. Anti-cancer effect of fenbendazole-incorporated PLGA nanoparticles in ovarian cancer. J Gynecol Oncol. 2023 Sep;34(5):e58.
[iii] Vlachou I, Parsonidis P, Mamagkaki A, Bouris I, Papasotiriou I. Teaching an old dog new tricks: The case of Fenbendazole. Cancer Treat Res Commun. 2022;32:100601.
[iv] Ibid.
[v] Chung, ibid.
[vi] https://www.merck-animal-health-equine.com/news/article/33
[vii] Dogra N, Kumar A, Mukhopadhyay T. Fenbendazole acts as a moderate microtubule destabilizing agent and causes cancer cell death by modulating multiple cellular pathways. Sci Rep. 2018 Aug 9;8(1):11926.
[viii] “A Drug Made for Animals and Taken by Humans to Treat Cancer: Fenbendazole.” The Mihaela Catalina Stanciu Foundation for Life. https://www.cancertreatmentsresearch.com/fenbendazole/
About Dr. Dan Sperling
Dan Sperling, MD, DABR, is a board certified radiologist who is globally recognized as a leader in multiparametric MRI for the detection and diagnosis of a range of disease conditions. As Medical Director of the Sperling Prostate Center, Sperling Medical Group and Sperling Neurosurgery Associates, he and his team are on the leading edge of significant change in medical practice. He is the co-author of the new patient book Redefining Prostate Cancer, and is a contributing author on over 25 published studies. For more information, contact the Sperling Prostate Center.
