Preclinical studies cannot provide sufficient evidence that ivermectin helps treat cancer in people

Key takeaway

Ivermectin is an attractive cancer drug candidate as it’s inexpensive and already clinically approved, albeit for parasitic infections. Some preclinical studies have indeed found promising results using ivermectin, but these studies were done in cell cultures and animals, not in humans. As such, they cannot provide sufficient evidence that ivermectin helps treat cancer in people. Further studies are needed to reliably determine ivermectin’s effectiveness and safety when used to treat cancer in humans.

Reviewed content

Verdict:

Unsupported

Claim:

Cancer patients should use ivermectin to treat cancer, as it augments the effect of cancer therapies

Verdict detail

Inadequate support: The reel cited preclinical studies showing promising results as evidence to support its recommendation. However, preclinical studies cannot provide sufficient data to determine a drug’s efficacy in humans, as they cannot adequately reproduce the complexity of the human body.

See our method of evaluation

Full Claim

“Should ivermectin be used by cancer patients to treat their disease? I would say yes, it’s something they should consider. It is a medication that has a lot of scientific research and data supporting the fact that it can help fight cancer.”; “It’s also gone extremely viral to the point where it’s likely every cancer patient in the world is taking it.”

A Facebook reel published at the end of June 2024 claimed that ivermectin “augments” the effect of cancer treatments and encouraged cancer patients to seek out ivermectin (the full video is archived and can be viewed here). The reel, which has received more than 148,000 views to date, was published by the Brio-Medical Cancer Center’s Facebook page and features one of its physicians Walter Kim.

On its website, the Center bills itself as “the premier integrative cancer clinic in North America”. An analysis of Facebook ads, published in 2023, reported that Brio-Medical Cancer Center was among alternative cancer centers advertising unproven treatments like Vitamin C and oxygen^[1]. At the time of writing, both treatments continue to be offered by the center, as indicated by its website.

Claims that antiparasitic drugs like ivermectin treat cancer aren’t new. A similar claim involving a dog dewormer, fenbendazole, also circulated on social media. Science Feedback explained that there wasn’t sufficient evidence that fenbendazole cures cancer in this review.

Such claims are potentially related to the rise in popularity of parasite “cleanses” promoted on social media, as reported by Vice and Rolling Stone. Science Feedback also reported on the same trend. This health fad is rooted in the (incorrect) belief that parasites are the cause of various conditions from autism to brain fog to cancer.

Ivermectin in particular came to public attention during the COVID-19 pandemic, when some groups touted it as a COVID-19 cure. Large-scale clinical trials eventually concluded that the drug provided no meaningful benefit to COVID-19 patients, as we reported in this review.

Researchers have also looked into ivermectin’s effectiveness against cancer, bolstered by some studies that found promising results. These findings, coupled with the fact that ivermectin is inexpensive and already clinically approved as a drug, make it an attractive cancer drug candidate.

Kim did acknowledge that ivermectin on its own is unlikely to cure cancer, but there’s currently a lack of clinical evidence to support his recommendation that cancer patients take ivermectin to boost the effectiveness of other therapies. We explain below.

Preclinical studies showed promising results in cell cultures and mice, not in humans

The reel’s caption stated that “Preclinical studies (in cell cultures and animal models) have shown promising results in inhibiting cancer cell growth and proliferation”. This is correct. A Google search for cancer studies involving ivermectin helped us identify a few published studies that contained favorable findings.

One of these was a 2014 study, which reported that ivermectin dampened the activity of a cell signaling pathway involved in cancer cell proliferation^[2]. This effect was observed in cell cultures of different types of cancer cells, including colon, lung, and skin cancers.

Another was a 2017 study, which reported that a combination of the chemotherapy drug paclitaxel and ivermectin reduced the growth of ovarian cancer cells implanted in mice^[3].

And a 2021 study in mice reported that the effect of anti-cancer immunotherapy was enhanced when combined with ivermectin, promoting breast cancer cell death^[4].

However, preclinical studies cannot provide sufficient evidence of a drug’s effectiveness in humans, even though they lay essential groundwork for future clinical studies in humans.

Firstly, cell cultures (cells growing in petri dishes in the lab) and animals used in preclinical studies can’t adequately represent a living human. The human body is much more complex than cells growing in dishes. Animals and humans can also differ in ways that affect a drug’s effectiveness, as explained here and here. For example, the way certain genes are expressed in mice is different from the way the same genes are expressed in humans. Therefore, randomized clinical trials in humans remain the gold standard for assessing a drug’s effectiveness in patients.

This brings us to our second point. Cancer drug candidates fail more often than they succeed during clinical trials. In fact, a 2019 analysis showed just a 3.4% success rate for anticancer drugs tested in clinical trials^[5].

Thirdly, preclinical studies don’t provide sufficient data on the effective dose and the risks of using ivermectin in cancer patients. While effective doses for treating parasitic infections with ivermectin are established, it’s unclear whether the same doses would also work for killing cancer cells in patients. There also isn’t enough data for us to determine if ivermectin would be effective for all types of cancer.

Finally, all drugs come with side effects, and ivermectin is no exception. Apart from the question of what dose is effective against cancer, another is whether that dose will be safe for cancer patients. These questions can only be resolved by conducting randomized clinical trials in humans.

A search on ClinicalTrials.gov for clinical trials mentioning ivermectin and cancer turned up just four results. And only two of these involved testing ivermectin’s efficacy against cancer. One is still in progress, while the status of the other is listed as “Unknown”.

In the reel, Kim asserted that “it’s likely every cancer patient in the world is taking it”, citing ivermectin’s “virality”. He also added that “something is wrong” if cancer patients aren’t being given ivermectin. This set of statements implied that there is widespread acceptance of ivermectin as a cancer treatment by the medical community. However, the reel offered no evidence to support this claim.

We reached out to Brio-Medical for comment and will update this review if new information becomes available.

Conclusion

Ivermectin is an attractive candidate for anti-cancer therapy as it’s inexpensive and already clinically approved, albeit for parasitic infections. Some preclinical studies have indeed found promising results, but these studies were done in cell cultures and animals, not in humans. As such, they don’t provide sufficient evidence to support the reel’s recommendation that cancer patients seek out ivermectin treatment. Further studies are necessary for reliably establishing ivermectin’s effectiveness and safety when used to treat cancer in humans.

REFERENCES

• 1 – Zenone et al. (2023) Advertising Alternative Cancer Treatments and Approaches on Meta Social Media Platforms: Content Analysis. JMIR Infodemiology.
• 2 – Melotti et al. (2014) The river blindness drug Ivermectin and related macrocyclic lactones inhibit WNT‐TCF pathway responses in human cancer. EMBO Molecular Medicine.
• 3 – Kodama et al. (2017) In vivo loss-of-function screens identify KPNB1 as a new druggable oncogene in epithelial ovarian cancer. PNAS.
• 4 – Draganov et al. (2021) Ivermectin converts cold tumors hot and synergizes with immune checkpoint blockade for treatment of breast cancer. npj Breast Cancer.
• 5 – Wong et al. (2019) Estimation of clinical trial success rates and related parameters. Biostatistics.