Mebendazole, or Vermox, a widely used anthelmintic drug for humans, has shown anti-cancer effects with several cancers including pancreatic cancer, TNBC, Glioblastoma (GBM), colon cancer and sarcoma.
Mebendazole (MBZ) was approved by the FDA in 1971 for treating pinworm infestations in humans, where it blocks, destabilises and degrades tubulin, a compound important in microtubules. Microtubules in worms play a crucial role in cellular functions, including maintaining cell structure and facilitating intracellular transport, essential for energy balance and metabolism. Damaging tubulin and microtubules reduces cellular glucose and restricts cell division, causing less parasites to form.
The tubulin and microtubules are both found in cancer cells. Studies have shown that MBZ can have much the same action in cancer cells, restricting metabolism, damaging structure and causing something aptly named as a 'catastrophe' in the cells .
Mebendazole is a benzimidazole. While similar antihelmintic drugs such as Fenbendazole, Ofendazole and Parbendazole have been developed, the benzimidazole core is also found in a wide variety of drugs such as antimicrobials, antivirals, antiparasites, anti-inflammatory, antioxidants, proton pump inhibitors, antihypertensives, anticoagulants, immuno-modulators, hormone modulators, CNS stimulants and even anticancer drugs.
The benzimidazole nucleus is already a building block of many marketed anticancer agents, such as Bendamustine for CLL and myeloma, breast cancer drug Abemaciclib, and PARP inhibitor Veliparib.
Anti-cancer effects of Mebendazole (MBZ)
Firstly, please note that Mebendazole is not approved by the WHO as an anti-cancer drug.
A 2019 meta-analysis (1) of Mebendazole as an anti-cancer agent concluded that, 'in vitro, it inhibits direct cytoxic activity and may work with both radiotherapy and chemotherapy to produce an anti-tumour immune response'. There was a previous review on 'Repurposed drugs' in 2014 which included Mebendazole (2).
Let me simply quote parts of the 2018 meta-analysis - "Several in vitro studies suggest that MBZ inhibits a wide range of factors involved in tumor progression such as tubulin polymerization, angiogenesis, pro-survival pathways, matrix metalloproteinases, and multi-drug resistance protein transporters".
It seems to work with or without Chemo- and Radiotherapy - "Mebendazole not only exhibits direct cytotoxic activity, but also synergizes with ionizing radiations and different chemotherapeutic agents and stimulates antitumoral immune response".
There is an increasing amount of in vivo research - "in vivo, MBZ treatment as a single agent or in combination with chemotherapy led to the reduction or complete arrest of tumor growth, marked decrease of metastatic spread, and improvement of survival" Yes, there is a study where it seems to help Oxaliplatin in head and neck cancer (3).
Mebendazole also appears to starve both worms and cancer cells of glucose. And 'it impedes cancer stem cells'. There is a little research with GBM on MBZ having angiogenesis-blocking abilities. Angiogenesis is the essential formation of blood supplies to tumours.
The researchers clearly warned that more research was needed especially to discover which chemotherapy drugs MBZ might enhance or hinder.
There maybe another reason it is an anti-cancer agent. Fasciolopsis buski is an intestinal fluke in humans. It is quite common especially in South East Asia. How many people with cancer took a holiday in Vietnam, Thailand, Cambodia, India or China? Mebendazole kills these Helminthics (5). That's its day job.
The accidental discovery of the anti-cancer effects of Mebendazole
Researcher Gregory Riggins at Johns Hopkins Cancer Center in Baltimore accidentally discovered that a similar drug, licensed for killing worms and parasites in animals (Fenbendazole) stopped his brain tumour experiments with mice - de-worming them with Fenbendazole (FBZ) stopped them being given brain tumours. In his experiments, all of the mice had been given brain tumour cells but the mice that had been de-wormed first with Fenbendazole didn’t develop any brain tumours! FBZ is also a benzimidazole drug but only approved for use with animals, so Riggens started looking at the approved-for-humans version - Mebendazole.
Mebendazole and GBM
So could Mebendazole be used to treat GBM, glioblastoma, the most deadly form of brain cancer, in humans?
Riggins then completed phase I clinical trials which primarily measure safety. And Mebendazole passed in humans – both children and adults. In 2011 Riggins was part of a larger pre-clinical trial that showed MBZ could increase survival times in glioma cell lines by as much as 67% (4). Again the latter finding is in vitro.
Professor Ben Williams used Mebendazole, along with other off-label drugs, as part of his GBM protocol in 1998. He beat his GBM in 18 months.
Mebendazole slows Pancreatic cancer
2021 research, again from Johns Hopkins, using mice given pancreatic cancer, showed that, particularly where the cancer had not already spread, the addition of Mebendazole to feed, significantly slowed the growth of the cancer in the pancreas (6). The team showed that by blocking the tubulin in the cancer cell, they collapsed its structure and caused cell death. MBZ also reduced inflammation and blood sugar levels.
Mebendazole and Breast cancer
As long ago as 2002, a Lung Cancer study had a short piece on the effectiveness with breast cancer cells. In a 2010 study in HER2 breast cancer cell lines, mebendazole was shown to have an effect, albeit limited.
In 2022, researchers from several US Medical Schools showed that MBZ could limit breast cancer metastasis to distant organs in mice (12). They also noted that it reduced stemness (from Cancer Stem Cells). 'MBZ reduced the expression of integrin β4 (ITGβ4), a protein linked to cancer stemness, thereby decreasing the population of therapy-resistant cancer stem cells'.
Mebendazole and TNBC
A 2024 study (8) in two parts, identified the potential of Mebendazole to inhibit the movement of Triple Negative Breast Cancer (TNBC) into the Central Nervous System. Then in vivo studies using mice then showed that while TNBC had a higher capacity to migrate than other cancers, Mebendazole could slow down the migration into the CNS .
In a completely separate study, again using mice but this time with late stage TNBC and using Ofendazole and Parbendazole plus gut bacteria known to make immune-enhancing Short Chain Fatty Acids, results showed increased survival, decreased tumor cell proliferation, and decreased metastasis in lungs and brain. The results also showed increased levels of fecal SCFAs butyrate, acetate, propionate and valerate with increased butyrate and propionate levels found in brain biopsies (9).
Mebendazole and Colon cancer
Research has shown that Mebendazole seems to inhibit BRAF, EGFR, ABL, ERK and MMP. There is 2014 research from Swedes Peter Nygren and Rolf Larsson on metastatic colon cancer showing that Mebendazole blocked growth (7). A 2023/2024 study, in mice bearing colon cancer, MBZ significantly reduced the tumor volume and tumor weight compared to the control group. Also, MBZ increases mean survival time and increases life span in the animals. MBZ was more selective than Doxycycline in inhibiting the proliferation of cancer cells; MBZ significantly reduced the tumor volume and tumor weight compared to the control group. Also, MBZ increases mean survival time and increase life span percentage in the animal study. This study suggested that Mebendazole strongly and selectively inhibited proliferation while inducing apoptosis in the colon cancer cells (10).
A pivotal Phase 2a clinical trial (NCT03925662) demonstrated that adding mebendazole (500 mg orally twice daily) to standard chemotherapy (Avastin + FOLFOX) in patients with metastatic colorectal cancer led to a significant improvement in overall response rate (65% vs 10% in control) and progression-free survival. Mebendazole also reduced VEGF levels, suggesting anti-angiogenic activity (13).
Mebendazole and other cancers
All this is not actually new news. Back in 1998, Professor Ben Williams used Mebendazole alongside other 'off-label' drugs metformin, melatonin, Accutane and tamoxifen to beat his own Glioblastoma.
Back in 2002, Mebendazole showed an effect against Lung cancer cells, causing dose-dependent apoptosis (cancer cell death). As a second part of this research, mice were given non-small cell lung cancer, and Mebendazole stopped the growth of the disease in vivo, with 80 per cent less metastases.
Work followed with adrenocortical cancer in vitro and in vivo in 2007 and the following year with melanoma, showing a similar pattern of results, as a thorough overview has shown (1).
By 2011, similar results were shown with osteosarcoma.
Two clinical trials are currently underway with brain tumours, one with high grade GBM (at Johns Hopkins) alongside Temozolomide; the other at Cohen's Children's Center in New York, with low grade GBM.
It's all a bit scant really, and much of it is in vtiro, but of course, funding is a major issue for proper clinical trials as the only people with the necessary funding are Big Pharma. Why would they support off-patent drugs?
How does Mebendazole work against cancer?
Mebendazole, or MBZ, also called Vermox, works against many types of parasitic worms (helminths) and their infections because it targets the synthesis of microtubules, by inhibiting tubulin polymerisation in their intestinal cells and killing them. It also starves the worms of glucose. It is taken by mouth and was originally created for animals, Mebendazole is effective and now has a long history of safety in humans.
Pinworms are an increasing threat to Americans with over 40 million developing an infection every year. Worm infections treated by Mebendazole include ascariasis, pinworms, hookworm, guinea worm and giardia.
So we know for certain that Mebendazole attacks microtubule formation in parasites. But microtubules are crucial to cancer cell formation also.
Microtubules are tiny fibres of tubulin protein that are involved in cell movement, cell division and mitosis (the transfer of the genome). Because each new created cell needs to be a copy of the parent, anything that disrupts the perfect copying can stop the whole process. University of California scientists have shown that the disruption of this process is how Taxol (paclitaxel) works, for example, although Taxol also attacks Bcl-2.
Starving the cancer of glucose and stopping the cancer feeding is also a property of Mebendazole.
Mebendazole or Fenbendazole?
Since the de-worming of the rats with Fenbendazole led to the complete failure of the researchers to give them brain cancer, you might be forgiven for wondering why oncologists aren't using Fenbendazole rather than Mebendazole, when it seems more potent.
Fenbendazole is another anti-helminthic drug. It too kills worms. It has been used in research studies with yet more cancers and there is reasonable research on about nine different cancers.
Joe Tippens used Fenbendazole with CBD oil to beat his Grade 4 Stage 4 NSCLC. It's a famous story. But there's a problem. Fenbedazole is only licensed for use with animals. No one has ever bothered to ask for a License for human use. Doctors would be struck off if they prescribed Fenbendazole! It's that simple.
What's the actual difference between the two compounds? A sulphur molecule in MBZ, that is not in FBZ.
Dosage of Mebendazole, side-effects, bioavailability, warnings
Dose? When used for Pinworm infections, MBZ is given at a dose of just 100 mg, with a second dose 3 weeks later. Other Helmonth infections require 100 mg twice a day for 3 days.
What about cancer? And here is the Truth - No one knows. There is no research on a dose for cancer patients. People are guessing.
Care Oncology in the UK used to give almost everybody 200 mg once or twice a day, but I have seen individuals and companies suggesting doses up to 1000 mg per day on the Internet. One research study (13) with Colon cancer (see above) used 2 x 500 mg a day.
Side effects? You need to be careful. Side-effects can include diarrhoea, nausea, appetite loss, bloating and rashes. MBZ can also increase liver enzymes and you should have a doctor monitor these. Care Oncology used MBZ one month on, one month off for these reasons.
Bioavailability is poor. MBZ is a poorly water-soluble and poorly lipid-soluble drug - only approximately 20% of the drug is absorbed into the blood stream. However, it is more fat soluble than water soluble, so the 20% can be improved by taking MBZ with fatty foods. The weak lipophilic properties of the drug do, however, allow it to cross the blood brain barrier.
The poor Bioavailability is why high doses are often used, but these come with increased side effects. Best to take MBZ with food for safety, not just for the low bioavailability.
Warnings - Not to be taken by pregnant women; and the antihistamine Cimetidine can significantly reduce its effectiveness.
***** The 3-in-1 anti-cancer Protocol - Ivermectin, Mebendazole and Fenbendazole
Chris Woollams writes, "I am increasingly asked about combining Ivermectin with either or both anthelmintic drugs Fenbendazole and Mebendazole. This question is quite popular in younger people with Turbo cancer, and especially in older patients with recurrent Prostate cancer, Colorectal cancer and Lung cancer where the existing drugs offer little hope.
I have written a Blog specifically on this subject. You can read it HERE. I call it the '3-in-one protocol' using Fenbendazole, Mebendazole and Ivermectin. I provide details links and doses and there is even recent research to support this protocol which deals with the mitochondrial stem cell connection".
Mebendazole - the bottom line
Yes, it seems to be good in research and in real life with brain tumours. For other cancers, the evidence is scant and often in vitro of the type skeptics and oncologists shower with derision. There is better research on more cancers for Fenbendazole. It is also very clear that we have no idea which chemo or other drugs it might enhance or hinder.
But it does seem to damage microtubules and cancer cell metabolism, reduce cancer cell oxygen, and sugar levels.
The first team at Care Oncology used it for 12 years. Some published research on their findings would have been helpful.
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References
1. Mebendazole as a Candidate for Drug Repurposing in Oncology: An Extensive Review of Current Literature; Andrea Emanuele Guerini, Luca Triggiani et al.
Cancers (Basel) 2019 Sep; 11(9): 1284.
3. Anthelmintic mebendazole enhances cisplatin's effect on suppressing cell proliferation and promotes differentiation of head and neck squamous cell carcinoma (HNSCC); Fugui Zhang et al.
Oncotarget 2017 Feb 21;8(8):12968-129825. The treatment of Fasciolopsis buski infection in children: a comparison of thiabendazole, mebendazole, levamisole, pyrantel pamoate, hexylresorcinol and tetrachloroethylene;
Trans R Soc,Trop Med Hyg. 1985;79(4):513-5
6. Mebendazole disrupts stromal desmoplasia and tumorigenesis in two models of pancreatic cancer; Tara Williamson et al,
Oncotarget, 2021; 12:1326-1338
9. A novel treatment to enhance survival for end stage triple negative breast cancer using repurposed veterinary anthelmintics combined with gutsupporting/immune enhancing molecules' Vijaya IragavarapuCharyulu et al;
Oncology Reprts, December 22, 202312. Mebendazole prevents distant organ metastases in part by decreasing ITGβ4 expression and cancer stemness; Joe, N.S., Godet, I., Milki, N. et al.
Breast Cancer Res 24, 98 (2022).