Ivermectin and Cancer: What Prostate Cancer Patients Should Know About This Emerging Research

Ivermectin vs. Cancer: A Critical Review of the Evidence

A comprehensive review of the science, the promise, and the limitations

Understanding the Buzz Around an Old Drug

You may have heard about ivermectin during the COVID-19 pandemic, but now this decades-old antiparasitic medication is generating interest in cancer research. For prostate cancer patients exploring every possible avenue for treatment, it's natural to wonder: could this inexpensive, widely-available drug offer hope? Let's look at what the science actually says—and what it doesn't say—about ivermectin as a potential cancer therapy.

Ivermectin has been used safely by hundreds of millions of people worldwide since the 1980s to treat parasitic infections. Its discoverers even won the Nobel Prize in 2015. Now, researchers are investigating whether this well-known drug might have anticancer properties. While the laboratory findings are genuinely exciting, it's crucial to understand that we're still in very early stages of this research.

How Might Ivermectin Work Against Cancer?

Scientists have discovered that ivermectin attacks cancer cells through multiple mechanisms in laboratory studies. Think of it as a Swiss Army knife—it appears to work on several fronts simultaneously:

Starving Cancer Cells: Research from China published in 2016 showed that ivermectin can trigger a process called "autophagy" in breast cancer cells, essentially causing them to consume themselves. The drug targets an enzyme called PAK1 and blocks the Akt/mTOR pathway—a critical growth highway that many cancers, including some prostate cancers, depend on for survival. In mice with breast tumors, this led to significant tumor shrinkage.

Triggering Cell Death: Studies on aggressive esophageal cancer found that ivermectin can cause cancer cells to self-destruct through a process called apoptosis. It attacks the mitochondria—the power plants of cells—causing them to fail. In treated mice, tumors grew much slower and the cancer spread far less to the lungs.

Exploiting Cancer Cell Weaknesses: Back in 2010, researchers discovered that ivermectin could kill leukemia cells by flooding them with chloride ions, creating fatal levels of oxidative stress while leaving healthy cells unharmed. This selective toxicity is exactly what cancer researchers look for.

Disrupting Multiple Cancer Pathways: A comprehensive 2020 review documented that ivermectin interferes with numerous cancer-driving pathways, including Wnt/β-catenin (important in prostate, colon, and breast cancers), and can even target cancer stem cells—the stubborn cells that often cause cancer to return after treatment.

The Immune System Connection: Turning "Cold" Tumors "Hot"

Perhaps the most exciting research comes from how ivermectin might help immunotherapy work better. Some tumors are "cold"—they hide from the immune system and don't respond well to immunotherapy drugs. Other tumors are "hot"—packed with immune cells actively fighting the cancer.

In 2021, researchers at City of Hope published remarkable findings: when mice with aggressive breast cancer received ivermectin along with immunotherapy (anti-PD-1 checkpoint inhibitors), something dramatic happened. The tumors became flooded with activated T-cells—the soldiers of the immune system. Cancers that didn't respond to immunotherapy alone started shrinking when ivermectin was added.

The results were striking: about 40% of mice treated with the combination became tumor-free, compared to little effect from either treatment alone. The mice that cleared their tumors even became immune to the cancer when researchers tried to give it to them again.

This is particularly relevant because some prostate cancers don't respond well to immunotherapy. Could ivermectin help wake up the immune system to recognize and attack these stubborn tumors? It's a tantalizing question that deserves investigation.

Overcoming Drug Resistance

Another promising angle is ivermectin's potential to make existing cancer treatments work better. Many cancers eventually become resistant to chemotherapy by developing pumps that push drugs out of cells. Laboratory research shows ivermectin can block these "efflux pumps," trapping chemotherapy drugs inside cancer cells where they can do their job.

In studies of osteosarcoma (bone cancer), combining ivermectin with the chemotherapy drug doxorubicin was far more effective than either drug alone. The combination overwhelmed cancer cells with oxidative stress while causing no significant toxicity in mice. Similar synergy has been seen with other chemotherapy drugs across multiple cancer types.

For prostate cancer patients dealing with castration-resistant disease or cancers that have stopped responding to hormone therapy, the idea of re-sensitizing tumors to treatment is appealing.

What About Human Studies?

Here's where we need to pump the brakes. Despite all the exciting laboratory findings, ivermectin has not been proven effective against cancer in human patients. Let me repeat that: there are currently no completed clinical trials showing ivermectin helps cancer patients.

The evidence we have in humans is extremely limited:

Small Case Series: In 2020, Brazilian doctors reported using high-dose ivermectin in a handful of pediatric leukemia patients. The drug was well-tolerated, and some patients experienced disease stabilization or even remissions. However, this was a tiny, uncontrolled case series—not enough to draw firm conclusions about effectiveness.

Anecdotal Reports: Some cancer patients have tried ivermectin on their own (sometimes using veterinary formulations) and reported feeling better. However, without scientific controls, we can't know if improvements were due to ivermectin, the placebo effect, or other treatments they were receiving.

Planned Trials: The first formal clinical trial is being planned in the United States to test ivermectin with an immunotherapy drug (balstilimab) in metastatic triple-negative breast cancer. This Phase 1 trial will primarily assess safety and determine appropriate doses. Results are not yet available.

The Evidence Strength Reality Check

Using rigorous evidence evaluation criteria, ivermectin as a cancer treatment currently scores about 3 out of 10 (30%) for evidence strength. Why so low despite all the exciting lab work?

• Strong laboratory evidence: Multiple independent research groups in different countries have confirmed ivermectin's anticancer effects in cells and animals. This diversity of evidence is encouraging.

• Multiple cancer types affected: Researchers have seen activity against leukemia, breast, esophageal, lung, colon, ovarian, pancreatic, prostate, melanoma, osteosarcoma, and brain cancers in laboratory models.

• Near-zero clinical evidence: We have essentially no data from properly controlled human trials. History teaches us that many drugs that work beautifully in mice fail in humans.

The bottom line: ivermectin's anticancer potential is grounded in biological plausibility and impressive preclinical work, but not in proven clinical effectiveness.

What Should Prostate Cancer Patients Do?

If you're considering ivermectin, here's practical guidance:

1. Don't abandon proven treatments. Ivermectin is not a substitute for surgery, radiation, hormone therapy, chemotherapy, or other established prostate cancer treatments.

2. Talk to your oncologist. If you're interested in ivermectin, have an honest conversation with your doctor. Some physicians may consider it as an adjuvant (add-on) therapy in specific situations, particularly if standard treatments aren't working.

3. Consider clinical trials. The best way to access ivermectin for cancer while contributing to medical knowledge is through a clinical trial. Ask your doctor if any trials are recruiting prostate cancer patients.

4. Be aware of dosing differences. The antiparasitic dose of ivermectin (typically 3-12 mg for an adult) is much lower than doses being studied for cancer (up to 60 mg or more). Don't assume the dose on a pill bottle is appropriate for cancer treatment.

5. Avoid veterinary formulations. Some patients have resorted to animal versions of ivermectin out of desperation. These are not formulated for human use and may contain harmful additives.

6. Maintain realistic expectations. Even if ivermectin eventually proves helpful, it will likely be as an adjuvant that improves other treatments, not as a standalone cure.

Why the Excitement?

Despite the lack of clinical proof, there are legitimate reasons researchers are pursuing this:

• Safety profile: Ivermectin has been used safely in hundreds of millions of people, so its side effects are well-characterized.

• Affordability: It's an inexpensive generic drug, which could make it accessible to patients worldwide if proven effective.

• Multi-targeted action: Unlike drugs that hit one pathway, ivermectin appears to attack cancer through multiple mechanisms simultaneously, potentially making it harder for cancer to develop resistance.

• Potential synergy: It might make existing treatments work better rather than replacing them.

The Bigger Picture

The story of ivermectin and cancer reflects a broader trend in oncology: drug repurposing. Researchers are systematically screening old, well-understood medications for new uses. It's an attractive strategy because these drugs have known safety profiles and could potentially be deployed quickly if they prove effective.

Other repurposed drugs being investigated for cancer include metformin (diabetes drug), statins (cholesterol medications), and aspirin. Some have shown promise; others have disappointed. Ivermectin is simply the latest chapter in this ongoing exploration.

Looking Ahead

The next few years will be critical. Clinical trials will finally test whether ivermectin's laboratory magic translates to real patient benefits. We'll learn whether it can:

• Help immunotherapy work in "cold" tumors
• Overcome resistance to hormone therapy or chemotherapy
• Shrink tumors or extend survival when added to standard treatments
• Improve quality of life

If the answers are yes, ivermectin could become a valuable addition to the cancer-fighting toolbox, particularly beneficial in low-resource settings. If the answers are no, it will join the long list of compounds that cured cancer in mice but not in people.

A Message for Patients

It's understandable to feel hopeful about ivermectin given the laboratory findings. It's equally understandable to feel frustrated that clinical trials are moving slowly. But the scientific method exists to protect you. Rigorous trials distinguish truly effective treatments from false hopes.

If ivermectin has genuine anticancer activity, the only way to prove it—and to establish safe, effective dosing—is through proper clinical research. Shortcuts around this process put patients at risk.

That said, every patient deserves autonomy in medical decisions. If you and your doctor decide to try ivermectin as an off-label adjuvant therapy (particularly in situations where standard options have been exhausted), that's a conversation worth having. Just go into it with eyes open about what we know and what we don't.

The Bottom Line

Ivermectin represents an intriguing hypothesis in cancer treatment, backed by substantial laboratory evidence but virtually no clinical proof. For prostate cancer patients, it's neither a miracle cure to embrace uncritically nor a worthless idea to dismiss out of hand. It's an active area of research deserving of rigorous investigation.

Stay informed, ask questions, advocate for clinical trials, and make decisions in partnership with your healthcare team. The goal isn't just hope—it's evidence-based hope that might one day become reality.

SIDEBAR: The Clinical Trial Gap – Why Isn't Ivermectin Being Tested More Widely?

The Patent Problem and the Valley of Death

If ivermectin shows such promise in laboratory studies, why aren't pharmaceutical companies rushing to test it in cancer patients? The answer lies in a fundamental challenge of drug development: the "repurposing dilemma."

Ivermectin's patent expired decades ago. It's now a generic medication that costs pennies per pill in many countries. While this would be wonderful news for patients if the drug proves effective, it creates a massive disincentive for pharmaceutical companies to invest in expensive clinical trials.

The Economics of Drug Development

Bringing a new cancer drug through Phase I, II, and III clinical trials typically costs $500 million to $2 billion and takes 8-15 years. Pharmaceutical companies make this enormous investment because they can recoup costs through patent protection—typically 20 years of market exclusivity where they're the only ones who can sell the drug at premium prices.

With ivermectin, there's no such protection. If a company spent $500 million proving ivermectin fights prostate cancer, any generic manufacturer could immediately start producing and selling it. The company funding the research would have no way to recover their investment, let alone make a profit.

This is what researchers call the "valley of death" for repurposed drugs—promising medications that fall into a funding gap between basic research and clinical application.

Who Could Fund These Trials?

Without pharmaceutical industry support, ivermectin cancer trials depend on:

Government Agencies: The National Cancer Institute (NCI) and National Institutes of Health (NIH) have limited budgets and numerous competing priorities. While they do fund some repurposed drug studies, the process is slow and highly competitive.

Academic Medical Centers: Universities and cancer centers can run trials, but lack the resources for large, multi-center Phase III studies that definitively prove effectiveness. The City of Hope study on ivermectin and immunotherapy is an example—excellent science, but limited to animal models so far.

Philanthropic Organizations: Cancer foundations and patient advocacy groups could theoretically fund trials, but most lack the tens of millions needed for rigorous studies.

Crowdfunding and Patient Advocacy: Some organizations are attempting to crowdsource funding for repurposed drug trials. However, these efforts rarely raise enough money for properly powered studies.

International Research: Countries with government-funded healthcare systems (like Cuba, Brazil, or India) may have more incentive to study cheap, effective treatments. Some ivermectin cancer research has emerged from these regions, though often with fewer resources than Western pharmaceutical trials.

The Regulatory Catch-22

Here's another wrinkle: even if ivermectin proves effective against cancer, who would seek FDA approval? Getting a new indication approved requires submitting extensive data to the FDA—a process that costs millions and requires a commercial sponsor. Generic drug manufacturers have little incentive to pursue this approval when they can already sell ivermectin legally for its approved uses.

This means doctors could prescribe ivermectin "off-label" for cancer if evidence supports it, but it would never be officially FDA-approved for that purpose. Insurance companies might refuse to cover it without formal approval, leaving patients to pay out-of-pocket.

What About Drug Modifications?

Some researchers are investigating modified versions of ivermectin that could be patented. These "ivermectin derivatives" might have improved cancer-fighting properties and would be eligible for patent protection, thus attracting pharmaceutical investment.

However, this creates its own problems: these modified drugs would likely be expensive, defeating one of ivermectin's main advantages—affordability and global accessibility.

The Current Trial Landscape

As of late 2025, a handful of small ivermectin cancer trials are in planning or early stages:

• A Phase I trial combining ivermectin with immunotherapy (balstilimab) in triple-negative breast cancer
• Small investigator-initiated studies at various academic centers
• Observational studies tracking cancer patients who choose to use ivermectin off-label

But these are tiny efforts compared to the hundreds of trials pharmaceutical companies run annually for patented cancer drugs.

Possible Solutions

Several mechanisms could help bridge this funding gap:

Public-Private Partnerships: Government agencies could partner with generic manufacturers to share trial costs and guarantee purchase agreements if the drug proves effective.

Advanced Market Commitments: International health organizations could guarantee to purchase large quantities of ivermectin for cancer treatment if trials succeed, creating a financial incentive for trial sponsors.

Patent Reform: Some advocates propose "orphan exclusivity" periods for repurposed drugs—granting a few years of market exclusivity even without a patent to reward companies that prove new uses for old drugs.

Prescription Data Exclusivity: European regulatory systems sometimes grant data exclusivity, preventing competitors from relying on your clinical trial data even if they can manufacture the drug.

Non-Profit Drug Development: Organizations like the Drugs for Neglected Diseases initiative (DNDi) develop treatments without profit motives. A similar model could work for cancer drug repurposing.

The Bottom Line for Patients

The lack of large-scale ivermectin cancer trials doesn't mean the drug doesn't work—it means our current drug development system isn't designed to test cheap, unpatentable medications effectively. This leaves patients in a frustrating position: promising laboratory evidence but no clear path to clinical proof.

Some oncologists, aware of this dilemma, may be willing to prescribe ivermectin off-label for patients who've exhausted standard options. This creates an informal "natural experiment" where patient experiences accumulate, though without the scientific rigor of controlled trials.

Patient advocacy groups can play a crucial role by:

• Lobbying for public funding of repurposed drug trials
• Supporting registry studies that track outcomes of off-label use
• Connecting patients with the few clinical trials that do exist
• Advocating for policy reforms that address the repurposing funding gap

A Call to Action

The ivermectin situation highlights a broader problem in medicine: our innovation system is optimized for developing expensive new drugs, not for discovering new uses for existing ones. Given that roughly 90% of new cancer drugs cost over $100,000 per year, finding effective uses for safe, cheap medications should be a priority.

Prostate cancer patients and advocacy organizations might consider:

• Contacting the NCI and asking them to prioritize ivermectin cancer trials
• Supporting organizations that fund repurposed drug research
• Participating in registries or observational studies if using ivermectin off-label
• Advocating for policy changes that create incentives for generic drug research

The irony is stark: ivermectin's very affordability—which would make it a godsend for cancer patients worldwide if effective—is precisely what prevents us from finding out whether it actually works.

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Resources for Clinical Trial Information:

• ClinicalTrials.gov: Search "ivermectin cancer" for current and recruiting studies
• National Cancer Institute Clinical Trials: https://www.cancer.gov/about-cancer/treatment/clinical-trials
• Informed Prostate Cancer Support Group: Stay updated on emerging treatment options

 

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Note: This article is for educational purposes only and does not constitute medical advice. Always consult with your healthcare provider before starting, stopping, or changing any treatment.

The Informed Prostate Cancer Support Group (IPCSG) is dedicated to providing evidence-based information to help patients make informed decisions about their care.