Fenbendazole vs. Traditional Radiation and Chemotherapy in Eradicating Cancer

Fenbendazole enhances the anti-cancer effects of many traditional therapies, and appears effective - as a single, stand-alone agent - against cancer stem cells

Fenbendazole Can Cure Cancer presents Case Reports of people who have treated their own cancers along with other articles to help understand how fenbendazole works. Previous articles covering other cancers are in the Archives link.

The use of fenbendazole to treat cancer is an example of the repurposing of a drug. Repurposed drugs are initially developed for use to address one condition - such as fenbendazole which was developed by Merck in the late 1950s to treat intestinal parasite infestation - and are subsequently discovered to be effective treating other conditions as well. With fenbendazole, that condition is cancer. Drug repurposing is a very effective way to develop “new” drugs to treat cancers because much of the heavy lifting has been done with respect to developing a drug. It is estimated to cost between $1 - $2.5 billion to discover a candidate compound and take it through the clinical trials needed for eventual FDA approval. This is time-consuming, with the average being about 12 years from concept to approval. The beauty of repurposing a drug that has been used for many years is that the safety profile is known, thereby reducing the likelihood that the drug will be rejected due to unknown toxicity and adverse events.

The downside to repurposing drugs is that the compound of interest could be off-patent, meaning that the financial rewards of expending the time and money to put the drug through the clinical trials needed for approval won’t be warranted. If the drug is “off-patent”, then anyone can manufacture it. This is one problem with fenbendazole as a treatment (cure) for cancer; there is no money in it! Therefore, it is almost impossible for a business to justify the time and expense required to formally “prove” that fenbendazole is an effective cancer treatment.

Since fenbendazole was discovered to have anti-cancer properties in 2002, there have been many clinical trails examining fenbendazole and cancer. However, the pattern is consistent: there are Phase I trials, the results look great and that’s it…no further testing. We can only speculate whether it was lack of scientific interest, institutional pressure or the daunting expense of the FDA process, or a combination of factors that led to the termination of these trials despite positive results. Nonetheless, it is safe to say that the FDA process for approving repurposed drugs should be modified to give proven safe, effective off-patent drugs like fenbendazole the opportunity to be repurposed.

So with the foregoing as a backdrop, here we are, essentially experimenting on ourselves with fenbendazole, a long-time proven safe antiparasitic veterinary medication that’s been around since 1961, that also has many anecdotal reports of success in treating various solid tumor cancers as well as blood cancers. If you’ve been reading the other articles in the Substack you’ll notice that while the Case Reports provide the anecdotal stories of “Hey, it worked for me!”, the other articles flesh out the scientific and practical issues related to using fenbendazole as a cancer treatment. This Substack article addresses some of the questions regarding the simultaneous use of fenbendazole while also receiving traditional chemotherapy and/or radiation treatments. While most of the studies that follow are in vitro (petrie dish) or experimental animal models, the information gained from them is, nonetheless, extremely valuable. Note: Most of the studies described below used mebendazole, a functional equivalent of fenbendazole (see * below).

Effects of Fenbendazole on Radiotherapy: Potentiation and Synergies

As a refresher, the mechanism through which ionizing radiation kills cancer cells is by disrupting the function of DNA within the cancer cell which then limits division of that cell or outright kills it. Mebendazole exhibits potent activity as a radiosensitizer by enhancing radiation-induced DNA damage in cancer cells (Markowitz, et al., 2017; Skibinski, et al., 2018; Zhang, et al., 2019). Another way that radiation kills cancer cells is by disrupting the DNA repair mechanisms that would normally rescue the cancer cell from the effects of radiation. Either way, targeted radiation kills cancer cells.

Glioblastoma - The question is how are the effects of radiation on cancer cells affected by the addition of fenbendazole (mebendazole)? Markowitz et al. (2017) found that prior treatment with mebendazole sensitized glioblastoma brain cancer cells to the effects of radiation, making them more susceptable to that radiation. That is, varying either the dose of mebendazole or the intensity (dose) of the radiation killed the cancer cells as expected. Higher doses of mebendazole required less radiation to achieve the toxic effects on the glioblastoma cancer cells. Mebendazole’s sensitizing effects were present whether given before or after radiation. They also found that mebendazole administration led to a greater disruption of DNA repair mechanisms than just radiation alone. So mebendazole not only sensitized the cancer cells to the effects of the radiation treatments, it also disrupted the cancer cell’s ability to repair the damage done by the radiation.

Breast Cancer - Zhang et al. (2019) examined the synergies between radiation and mebendazole on triple negative breast cancer cells. Triple negative breast cancer describes cancer cells that are do not have receptors for estrogen, progesterone or human epidural growth factor. One unfortunate phenomenon that can occur with cancer is that the radiation used to treat the cancer can convert those cancer cells into particularly lethal cancer stem cells. Currently there are no approved effective pharmacological treatments for cancer stem cells. What Zhang et al. (2019) found was that mebendazole combined with radiation not only killed more cancer cells than radiation alone, mebendazole also reduced the number of resultant cancer stem cells that normally occur after radiation. These findings indicate that mebendazole should be used in combination with any radiation treatment to prevent that radiation treatment from spawning lethal cancer stem cells. The experiment also examined estrogen receptor positive cells and found that mebendazole alone had cytotoxic effects on triple negative and estrogen positive cells, and and that mebebendazole potentiated the cytotoxic effects of radiation on both types of cells as well.

“mebendazole so vastly outperformed vincristine - the current gold standard treatment- that the authors made the bold case for the replacement of vincristine with mebendazole as the go-to treatment for glioblastoma (Dewitt et al., 2017).”

An exciting study just published in late December 2022, by Joe et al. (2022) studying breast cancer, found that mebendazole, by itself, reduces integrin β4 (ITGβ4) expression, a genetic marker linked to the presence of cancer stem cells. ITGβ4 has previously been implicated in the development of cancer stem cells and this study indicates that mebendazole is highly effective in killing highly lethal cancer stem cells when all other treatments fail.

Practically speaking, wouldn’t it make sense to try fenbendazole (mebendazole) first, before any harmful, expensive, side-effect laden chemotherapies and/or radiation? However, should the traditional route of radiation be taken, and cancer stem cells result, mebendazole appears to be the best available remedy for the cancers that may result from the radiation treatments as well. Quite an amazing finding!

Effects of Fenbendazole on Chemotherapy: Potentiation and Synergies

Glioma - Mebendazole was found to have a synergistic anti-cancer effect when combined with immunochemotherapy (anthracyclines, temozolomide, gemcitabine). Cancer cells that are typically only partially sensitive to temozolomide alone were completely eradicated with the addition of mebendazole (Kipper, et al. 2018).

In another study comparing mebendazole with vincristine (which also disrupts the microtubule apparatus of the cancer cell), and is the current gold standard of chemotherapy for glioblastoma, mebendazole so vastly outperformed vincristine that the authors made the bold case for the replacement of vincristine with mebendazole as the go-to treatment for glioblastoma (Dewitt et al., 2017).

Head and neck squamous cell carcinoma - Mebendazole had a more powerful anti-proliferative effect than the drug cisplatin, and had a synergistic effect on cancer cell growth when combined with cisplatin, killing more cancers cells than cisplatin alone (Zhang et al., 2017).

Cancer Stem Cells and Refractory Clones: Why Traditional Treatments Fail

Traditional therapies fail when cancer cells change as a result of those treatments and become more lethal cancer stem cells and/or refractory cells. An imperfect analogy is the development of antibiotic resistance that can occur with the overuse of some antibiotics. In the case of traditional cancer treatments, while well intended, their use can spawn even more deadly cancer stem cells or refractory clones that are immune to the treatments that spawned them.

Fortunately, we are learning in the lab what we seem to already know from the field, that fenbendazole (mebendazole) is effective against cancer stem cells/refractory clones. It is worth repeating that Zhang et al. (2019), studying breast cancer, found that mebendazole combined with radiation, not only killed more cancer cells than radiation alone, mebendazole also reduced the number of resultant cancer stem cells that normally occur after radiation. Furthermore, Joe et al. (2022), also studying breast cancer, just found genetic evidence - reduction of ITGβ4 - that mebendazole (fenbendazole) impairs the development of these particularly lethal cancer stem cells that are a direct result of radiation therapy.

If you’ve been studying the Case Reports in this Substack, you’ll recall that many of the instances involving fenbendazole eradicating cancer occurred AFTER traditional treatments had failed. It is reasonable to speculate that those Case Reports involved the development of traditional treatment-immune cancer stem cells/refractory clones that were effectively eradicated by subsequent fenbendazole treatment. These Case Report data represent the ‘knowledge from the field"‘ referenced above.

Fenbendazole not only cures cancer, fenbendazole also appears to cure those more lethal cancers composed of cancer stem cells/refractory clones caused by the therapeutic radiation intended to treat those cancers.

According to Guerini et al. (2019), “The effectiveness of anticancer treatments is limited by refractory cell clones that are responsible for tumor progression. Intrinsic or acquired resistance is mediated by many molecular mechanisms including unregulated activation of pro-survival pathways and DNA repair enzymes, mutation or inactivation of tumor suppressors like p53, high levels of detoxifying proteins and transporter pumps mediating drug efflux, and immunotolerance and abnormal angiogenesis. Although resistant clones, including so called “cancer stem cells”, represent one of the main pitfalls of cancer treatment, there are currently no approved drugs specifically targeting this cell population.” The key word in the last sentence is “approved.” It appears that fenbendazole (mebendazole) is very likely to be effective in preventing and killing cancer stem cells.

Takeaway messages from this article.

1. Fenbendazole alone seems to work better than traditional chemotherapies in many of these experimental preparations (Dewitt et al., 2017, Markowitz et al., 2017, Zhang et al., 2019 as examples) so much so that some have gone so far to suggest that the current gold standard of chemotherapy for glioblastoma, vincristine, be replaced by mebendazole (Dewitt et al., 2017). Certainly the Case Reports in this Substack indicate that fenbendazole can eradicate cancers when traditional therapies fail.

2. Fenbendazole (mebendazole) can be used along with radiation and/or chemotherapies. It doesn’t appear to interfere or disrupt the therapeutic actions of these treatments, rather it is clear that fenbendazole potentiates or synergizes with those treatments making them more effective! As a side note in Case Report: Metastatic Breast Cancer, age 83 it was reported that targeted radiation of the spine was performed on several tumors that were causing pain. The radiologist reported that the radiation eradicated the tumors much quicker than expected, days vs. weeks.

3. Physiological dosages: The dosage of mebendazole tested in many experimental models are in the range of 25–100 mg/kg daily, which correspond to 2.03–8.13 mg/kg (142–569 mg daily for a person weighing 70 kg), which is well below the currently approved dosages for anti-parasite therapy (Guerini et al. 2019). This is important because if the anti-cancer effects in the experimental preparations are only achieved with supraphysiological dosages the application of any insights are complicated. Fortunately, that’s not the case here and those that have been self-treating their cancers have been, for the most part, using effective dosages.

4. There is a very interesting phenomenon happening with respect to fenbendazole and cancer. Humans are self-treating with fenbendazole and eradicating their cancers and basic science is endeavoring to find out why! The usual process is completely inverted. Usually in pharmacological medical science an initial observation (discovery) is followed up by reduced preparation experiments (petrie dish studies etc) that move on to whole experimental animal studies then on to clinical trails in humans. Eventually, many years down the road and many millions $ later, an expensive drug is born.

5. It is most interesting to see that virtually all of the basic science, in one manner or another, supports the claim that Fenbendazole Can Cure Cancer!

*Fenbendazole vs. Mebendazole vs. Albendazole vs. Flubendazole: Because the benzimidazoles are very similar chemically and they have very similar mechanisms of action with respect to disrupting microtubule function, specifically defined as binding to the colchicine-sensitive site of the beta subunit of helminithic (parasite) tubulin thereby disrupting binding of that beta unit with the alpha unit of tubulin which blocks intracellular transport and glucose absorption (Guerini et al., 2019). If someone asks you how fenbendazole kills the cancer cells, the answer is in italics in the previous sentence.

The class of drugs known as benzimidazoles includes fenbendazole, mebendazole, albendazole and flubendazole. Mebendazole is the form that is approved for human use while fenbendazole is approved for veterinary use. The main difference is the cost. Mebendazole is expensive ~$450 per pill, while fenbendazole is inexpensive ~48 cents per 222 mg free powder dose (Williams, 2019). As you may recall, albendazole is the form used to treat intestinal parasites in India and these cost 2 cents per pill. FYI, to demonstrate how Americans get screwed by Big Pharma, two pills of mebendazole cost just $4 in the UK.

While most of the pre-clinical research uses mebendazole, probably because it is the FDA-approved-for-humans form of fenbendazole, virtually all of the self-treating clinical reports involve the use of fenbendazole. It would be helpful if future investigations simply used fenbendazole as a practical matter.

If you would like to report your experiences with fenbendazole you can do so by email fenbendazole77@gmail.com. Also, if you know of people who’ve tried fenbendazole, and it didn’t work, we’d be especially interested in hearing from you now. Understanding the conditions and factors that impede the success of fenbendazole in treating cancer are just as valuable, maybe even more valuable, than those that facilitate its success.

References

Chiang RS, Syed AB, Wright JL, Montgomery B, Srinivas S (2021) Fenbendazole Enhancing Anti-Tumor Effect: A Case Series. Clin Oncol Case Rep 4:2 https://www.scitechnol.com/abstract/fenbendazole-enhancing-antitumor-effect-a-case-series-14307.html

De Witt, M., Gamble, A., Hanson, D. et al. Repurposing Mebendazole as a Replacement for Vincristine for the Treatment of Brain Tumors. Mol Med 23, 50–56 (2017). https://doi.org/10.2119/molmed.2017.00011

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 8, 11926 (2018). https://www.nature.com/articles/s41598-018-30158-6

Guerini, A. E., et al (2019). Mebendazole as a Candidate for Drug Repurposing in Oncology: An Extensive Review of Current Literature. Cancers, 11(9), 1284. https://doi.org/10.3390/cancers11091284

Joe, N.S., Godet, I., Milki, N. et al. Mebendazole prevents distant organ metastases in part by decreasing ITGβ4 expression and cancer stemness. Breast Cancer Res 24, 98 (2022). https://doi.org/10.1186/s13058-022-01591-3

Kipper, F.C.; Silva, A.O.; Marc, A.L.; Confortin, G.; Junqueira, A.V.; Neto, E.P.; Lenz, G. Vinblastine and antihelmintic mebendazole potentiate temozolomide in resistant gliomas. Investig. New Drugs. 2018, 36, 323–331.

Markowitz, D.; Ha, G.; Ruggieri, R.; Symons, M. Microtubule-targeting agents can sensitize cancer cells to ionizing radiation by an interphase-based mechanism. Onco. Targets Ther. 2017, 10, 5633–5642. https://www.dovepress.com/microtubule-targeting-agents-can-sensitize-cancer-cells-to-ionizing-ra-peer-reviewed-fulltext-article-OTT

Mukhopadhyay T, Sasaki J, Ramesh R, Roth JA. Mebendazole elicits a potent antitumor effect on human cancer cell lines both in vitro and in vivo. Clin Cancer Res. 2002 Sep;8(9):2963-9. PMID: 12231542. https://pubmed.ncbi.nlm.nih.gov/12231542/

Skibinski, C.G.; Williamson, T.; Riggins, G.J. Mebendazole and radiation in combination increase survival through anticancer mechanisms in an intracranial rodent model of malignant meningioma. J. Neurooncol. 2018, 140, 529–538 https://pubmed.ncbi.nlm.nih.gov/30414098/

Williams, David (2019) A cure for cancer hidden in plain sight https://fenbendazole.s3.amazonaws.com/A-Cure-for-Cancer-Hidden-in-Plain-Sight-July-2019-Dr-David-Williams.pdf

Zhang, L.; Bochkur, D.M.; Yazal, T.; Dong, K.; Nguyen, A.; Yu, G.; Dao, A.; Bochkur, D.M.; Duhachek-Muggy, S.; Bhat, K.; et al. Mebendazole Potentiates Radiation Therapy in Triple-Negative Breast Cancer. Int. J. Radiat. Oncol. Biol. Phys. 2019, 103, 195–207. https://www.redjournal.org/article/S0360-3016(18)33688-5/fulltext

Note: there are hundreds of other relevant articles that examine effects of fenbendazole (mebendazole) on cancer, the above are selected because they were specifically referenced in this Substack.

Disclaimer:
Statements on this website have not been evaluated by the Food and Drug Administration. The contents of this website is for educational and informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis or treatment. This website does not provide any kind of health or medical advice of any kind. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. The case reports presented reflect the real-life experiences and opinions of other readers or users of the website. The experiences of those readers or users are personal to those particular readers/users and may not necessarily be representative of all readers/users. We do not claim, and you should not assume, that all other readers/users will have the same experiences. Do you own research, consult with relevant medical professionals before attempting to self-treat for any condition.