Ivermectin + mebendazole for cancer

Drug repurposing · Critical paper review · 30 October 2026

Ivermectin + mebendazole for cancer: a rationale is not proof

What the new review actually shows about the combination, the human trials and the authors’ commercial interests.

The title promises a comprehensive review of combination ivermectin and mebendazole as an adjunctive cancer treatment. But the central scientific argument is assembled largely from studies of the two drugs separately. The distinction matters: evidence that each compound affects cancer biology does not establish that taking them together improves a patient’s outcome.

The 44-page paper by Nicolas Hulscher, James Thorp, Kelly Victory, Peter Gillooly, Peter McCullough and Harvey Risch was posted to Zenodo on 19 October 2026 as a preprint. It is a narrative review, not a new experiment, and its methods explicitly acknowledge that it is not a systematic review with recorded screening yields. It presents a research rationale, selected human evidence and an argument for more trials. [1]

The central finding

The combination remains an unproven therapeutic hypothesis. The review identifies no published experiment testing the pair together in cells or animals and presents no randomized human results establishing the pair’s benefit. Its cited human combination cohort is retracted. Mebendazole has a small positive randomized trial as an addition to chemotherapy, but that trial did not include ivermectin. [1] [3] [4]

What the laboratory evidence can—and cannot—tell us

The review counts 29 mechanisms for ivermectin and 26 for mebendazole, merged into 37 classes across preclinical models of 25 human malignancies. These are counts of reported targets or processes, not 37 independently validated treatment benefits. “Human malignancies” here includes human cancer cells grown in laboratories or implanted into animals; it does not mean patients with 25 cancers benefited. [1]

In silico

Predicted interactions

Docking and target predictions contribute to parts of the mechanistic literature. They do not establish drug activity at achievable exposure or validate the two-drug combination.

In vitro

Effects in cells

Both drugs have individual anticancer findings. The review reports no published cell experiment testing ivermectin plus mebendazole together.

In vivo

Effects in animals

There are animal findings for individual drugs and other combinations. The review reports no animal experiment testing this specific pair.

In humans

Combination benefit unproven

The only pair-specific cohort is uncontrolled, based on patient reports and retracted. There is no randomized comparison establishing an added benefit.

Evidence map for the pair, based on the attached review; this is not an independent systematic audit of every preclinical reference. [1]

The proposed complementarity is biologically interesting. The authors connect effects on hypoxia signaling, DNA repair, metabolism and immune cells. But these effects come from different experimental settings. They have not been shown to occur together, at useful concentrations, in the same patient’s tumor.

Exposure is another missing bridge. Many cell experiments use concentrations above those reached with standard antiparasitic dosing. The review’s example of mebendazole reaching 7.1 micromolar in brain tissue comes from mice, not measurements in human brain tumors. Neither a modeled target interaction nor tolerating a high dose establishes adequate, sustained drug exposure at a patient’s tumor. [1]

The authors also identify potential opposition: mebendazole destabilizes microtubules, whereas ivermectin can stabilize them in experimental systems. They discuss potentially conflicting effects on MEK–ERK signaling as well. Opposite actions do not automatically imply antagonism, just as different targets do not establish synergy. For this pair, synergy, additivity and antagonism remain unresolved. A direct comparison of each drug alone and the combination, over relevant concentrations and schedules, is needed. [1]

The human combination study: what does 84.4% mean?

The review’s most prominent combination statistic comes from the authors’ own telemedicine cohort. It enrolled 197 people with different cancers; 122 completed six-month follow-up. Of those respondents, 103 reported no evidence of disease, regression or stable disease, producing the widely repeated 84.4% composite figure. These are historical results from a retracted report, not an established probability of benefiting from the treatment. [2] [3]

197 enrolled → 122 responded → 103 counted in the composite

Composite: 40 + 19 + 44 = 103. The 19 progression reports were excluded.

40reported no evidence of disease

19reported regression

44reported stable disease

19reported progression

75 participants did not complete follow-up. The 84.4% denominator is 122, not 197. The figure combines different disease states and is not an objective tumor response rate. [1] [2]

There was no control group and no independent radiological verification of the reported outcomes. Some participants also received chemotherapy, radiotherapy or surgery. A person reporting no evidence of disease at follow-up is not necessarily someone whose cancer disappeared because of the capsules: the starting disease state, previous treatment and intervening standard care matter. Stable disease likewise cannot be assigned to the combination without knowing what would have happened otherwise.

The 38.1% missing follow-up adds another major uncertainty. Similar reported treatment frequencies among respondents and the initial cohort do not establish that the missing patients had similar outcomes. Nor does a nonsignificant difference prove equivalence or exclude selection bias.

Anticancer Research retracted the cohort report in October 2026; the review dates the action to 1 October and disputes it at length. The retraction is independently recorded in PubMed. The authors’ disagreement does not reverse its status. This critique does not infer fabrication: even perfectly calculated percentages from this design would not establish a treatment effect. [1] [3]

Mebendazole: the strongest human signal—and the unsuccessful studies

The clearest positive controlled result is the 2022 Hegazy trial in metastatic colorectal cancer. Forty patients received bevacizumab plus FOLFOX4, with either mebendazole or placebo added. At 12 weeks, responses were reported in 13 of 20 versus 2 of 20; median progression-free survival was 9.25 versus 3 months. This is a meaningful signal worth investigating. It tests adding mebendazole to that regimen, not mebendazole alone or ivermectin plus mebendazole. [4]

Its limitations matter: only 20 patients per group, a single-center design as described in the review, and retrospective registration acknowledged in the original abstract. The review reports no statistically significant difference in one-year overall survival. That does not prove absence of a survival effect, but the study does not establish one. Independent, larger confirmation is needed before generalizing to other cancers or drug combinations. [1] [4]

Study	What was reported	What it establishes
Hegazy 2022 40 colorectal-cancer patients	Higher response proportion and longer progression-free survival with mebendazole added to bevacizumab/FOLFOX4.	A small randomized positive signal for this specific add-on regimen. No ivermectin. [4]
Patil 2022 88 recurrent-glioblastoma patients	Nine-month survival was 36.6% with temozolomide/mebendazole and 45% with lomustine/mebendazole; both missed the prespecified 55% benchmark.	A failed efficacy benchmark. Both groups received mebendazole, so its contribution cannot be isolated. A favorable post hoc subgroup does not rescue the primary result. [5]
Mansoori 2021 11 enrolled; 10 started continuous treatment	All 10 stopped for progression and/or deterioration; eight had CT assessment. Exposure was variable and difficult to sustain.	No demonstrated single-agent benefit in this refractory gastrointestinal-cancer setting. Pharmacokinetic problems help explain failure but do not convert it into success. [6]
METRICS / Agrawal 2019 95 glioblastoma patients	Reported median survival of 26.3 months with a four-drug protocol plus standard care, compared with historical cohorts.	Uncontrolled; mebendazole cannot be separated from metformin, atorvastatin and doxycycline. The article is now retracted. [7] [8]

Randomization alone does not answer every question: the Patil trial randomized between two regimens that both contained mebendazole.

An update missing from the review

The review describes METRICS as subject to an unresolved 2023 expression of concern. However, Frontiers retracted the article on 13 October 2026, before the review’s 19 October posting. The notice reports regulatory findings concerning ethics approval and informed consent, along with inaccuracies and inadequate data quality control. Consequently, two of the review’s three “positive” efficacy reports are now retracted: METRICS and the authors’ combination cohort. This does not invalidate the separate colorectal trial. [8] [3]

The gastrointestinal trial also deserves more attention than the label “neutral” suggests. Four of eight patients with CT assessments met proposed hyperprogression criteria. That observation does not prove mebendazole accelerated their cancers: the study was small, uncontrolled and enrolled patients with advanced progressing disease. Nevertheless, its investigators explicitly left a possible treatment contribution unresolved. Saying no study proved worse outcomes must not become reassurance that worsening has been excluded. [6]

Ivermectin: preliminary combination data, not proven single-agent activity

The formal oncology result cited for ivermectin is a 2025 ASCO meeting abstract from a phase I/II trial combining it with balstilimab, an anti-PD-1 antibody, in metastatic triple-negative breast cancer. It is not an ivermectin–mebendazole study. Nine patients had entered; eight were evaluable, with one partial response, one stable disease and six progressive disease outcomes reported. Median progression-free survival was 2.5 months. [9]

The abstract also reports a four-month clinical-benefit estimate of 37.5%, with a very wide confidence interval of 15.3–91.7%. These small, preliminary, uncontrolled data cannot determine whether ivermectin added anything to immunotherapy. The authors’ tolerability assessment supports continued investigation of the tested regimen; it is not proof of anticancer efficacy. [9]

The review presents no completed trial establishing ivermectin alone as a cancer treatment. Its separate compilation of 36 cancer patients given ivermectin principally for parasitic infections concerns tolerability in people who happen to have cancer—not treatment of their malignancy. Surveys of ivermectin use similarly document behavior, not tumor response. [1] [17]

The registered ICONIC study compares two ivermectin doses alongside checkpoint inhibition and plans to assess immune changes. Its listed primary endpoint is a blood T-cell activation measure. There are no results in the cited record, no mebendazole arm and no ivermectin-free comparator. Registration is evidence that a question is being investigated, not that a treatment works. [18]

Another registration: NCT02366884

This phase II “atavistic chemotherapy” protocol lists both ivermectin and mebendazole among candidate anti-infectives. It describes randomized, single-blind allocation among broad multi-drug strategies, not a specified ivermectin–mebendazole comparison. The record does not establish which participants received ivermectin, its dose, or whether the pair was administered together. Enrollment of 250 is estimated. Status is unknown, last updated 6 April 2022, with no posted results. It documents a registered research plan, not demonstrated efficacy. [20]

The investigator also provides selected case narratives, but the materials checked do not identify ivermectin exposure or report randomized results attributable to it. No peer-reviewed results publication linked to this trial was located in this check. [21]

What about safety trials and individual success stories?

The review correctly separates four mebendazole studies primarily designed to assess safety or dosing. Their populations were small and their regimens differed. They help define what can be studied under monitoring; they do not collectively establish the efficacy or safety of ivermectin–mebendazole.

Study and population	Main contribution and limitation
Gallia 2021: 24 adults with newly diagnosed high-grade gliomas	Mebendazole with temozolomide; dose and tolerability data. Four patients at the highest dose developed grade 3 liver-enzyme elevations, reversible with reduction or stopping. No controlled efficacy comparison. [10]
Patil 2020: 11 recurrent-glioma patients	Dose-finding with chemotherapy and/or reirradiation. Tolerated dosing depended on the accompanying regimen. [11]
Krystal 2024: 10 children/young adults with high-grade gliomas	Mebendazole with bevacizumab and irinotecan; a small phase I feasibility and tolerability study. [12]
Phan 2025: 17 pediatric brain-tumor patients	Mebendazole alone; no dose-limiting toxicity, but adverse events occurred. Mean progression-free survival was 7.6 weeks; the authors reported limited single-agent efficacy. [13]

There are also individual mebendazole reports worth acknowledging: prolonged control in one patient with metastatic adrenocortical carcinoma and a reported response in refractory metastatic colon cancer. They are clinical observations, not proof that a comparable patient will respond. The ovarian-cancer case involved multiple repurposed medicines, preventing attribution to mebendazole. None validates adding ivermectin. [14] [15] [16]

Nor does extensive antiparasitic use settle oncology safety. Dose, duration, formulation, liver function and other medicines affect risk. The review discusses neurotoxicity, liver injury and drug interactions. Some cited toxicity reports involve veterinary fenbendazole as well as ivermectin; they should not be misrepresented as direct evidence about mebendazole or this exact pair. [1]

The Wellness Company connection is directly relevant

All six authors list The Wellness Company as an affiliation. Their declaration on page 34 states:

“All authors are affiliated with and/or receive salary support from The Wellness Company (TWC).” Conflict of interest statement, attached review. [1]

That wording establishes a disclosed company relationship for every author; it does not establish that every author is salaried, nor specify individual remuneration. The commercial connection is concrete: the company’s own website offers a prescription compounded ivermectin–mebendazole product and advertises consultations for off-label use. [19]

A financial conflict does not automatically make a scientific claim false. It does make independence, study design and interpretation particularly important. Here, authors linked to the seller are reviewing the drugs, defending their own retracted customer cohort, and classifying that cohort as a positive study. The paper’s statement that it received no external funding does not remove these employment or commercial relationships. [1]

The generic status of the ingredients does not eliminate commercial incentives. Compounding, prescribing services and product sales can generate revenue without a new drug patent. A fair assessment applies the same evidentiary standards to this business model as to any other company promoting a treatment.

The conclusion the evidence supports

The review contains useful biological hypotheses and openly acknowledges several major limitations. Its own limitations section says the human evidence is insufficient to support use outside a trial, yet elsewhere it argues that restrictions on such use are too strong. That tension should be visible to readers. [1]

Its positive/neutral scorecard is also a poor substitute for weighing evidence. A retracted uncontrolled cohort, a retracted four-drug historical comparison and a small randomized trial cannot be treated as three equivalent confirmations. Failed efficacy benchmarks remain relevant even when they do not demonstrate harm. Safety studies answer a different question from survival trials.

Mebendazole has a preliminary controlled clinical signal in one colorectal-cancer regimen, alongside unsuccessful trials and case reports. Ivermectin has limited early human data with immunotherapy. The ivermectin–mebendazole pair has neither established synergy nor reliable evidence of clinical benefit. The next useful step is direct combination testing followed by appropriately controlled studies in defined cancers, with verified outcomes and independent oversight.

This is an evidence review, not a dosing protocol. The findings do not justify replacing or delaying established cancer care. Source and publication-status checks were completed on 30 October 2026; future trials may change the assessment.

References and source notes

The attached preprint was read in full for its clinical and interpretive claims. Key trials and publication notices were checked against original abstracts, accessible full texts and official records. The colorectal numerical results were checked against its primary abstract; the one-year survival statement is attributed to the review. Not all 151 references underwent a full-text audit.

1. Hulscher N et al. Combination Ivermectin and Mebendazole: A Comprehensive Review… Zenodo preprint, 19 October 2026. Sections 8–11 and declarations are especially relevant; not a new combination experiment.
2. Hulscher N et al. Real-world Clinical Outcomes of Ivermectin and Mebendazole in Cancer Patients. Anticancer Research, 2026. Retracted. DOI: 10.21873/anticanres.18194. Cited to examine historical claims, not support efficacy.
3. Retraction of the Hulscher combination cohort. Anticancer Research. 2026;46:5877. DOI: 10.21873/anticanres.18425. Retraction status independently verified; the review disputes the decision.
4. Hegazy SK et al. Mebendazole; from an anti-parasitic drug to a promising candidate for drug repurposing in colorectal cancer. Life Sciences. 2022;299:120536. Randomized trial; primary abstract checked.
5. Patil VM et al. Mebendazole plus lomustine or temozolomide in patients with recurrent glioblastoma. EClinicalMedicine. 2022;49:101449. Randomized phase II trial; both arms contained mebendazole.
6. Mansoori S et al. A phase 2a clinical study…in patients with advanced gastrointestinal cancer. Scientific Reports. 2021;11:8981. Full text checked, including progression and hyperprogression discussion.
7. Agrawal S et al. A New Method for Ethical and Efficient Evidence Generation for Off-Label Medication Use in Oncology. Frontiers in Pharmacology. 2019;10:681. Retracted. METRICS historical claims only.
8. Frontiers Editorial Office. Retraction: A new method for ethical and efficient evidence generation… 13 October 2026. DOI: 10.3389/fphar.2026.2021924. Updates the status given in the reviewed preprint.
9. Yuan Y et al. Ivermectin with balstilimab in metastatic triple-negative breast cancer. JCO. 2025;43(suppl):e13146. Preliminary conference abstract; nine enrolled, eight evaluable.
10. Gallia GL et al. Mebendazole and temozolomide in newly diagnosed high-grade gliomas. Neuro-Oncology Advances. 2021;3:vdaa154. Phase I; liver-enzyme toxicity reported.
11. Patil VM et al. Reverse swing-M. Cancer Medicine. 2020;9:4676–4685. Phase I dose-finding.
12. Krystal J et al. A phase 1 study of mebendazole with bevacizumab and irinotecan in high-grade gliomas. Pediatric Blood & Cancer. 2024;71:e30874.
13. Phan P et al. Phase 1 study of mebendazole therapy for refractory/progressive or recurrent pediatric brain tumors. Neuro-Oncology Practice. 2025;12:1092–1098. Primary abstract checked.
14. Dobrosotskaya IY et al. Mebendazole monotherapy and long-term disease control in metastatic adrenocortical carcinoma. Endocrine Practice. 2011;17:e59–e62. Single patient.
15. Nygren P, Larsson R. Tumour remission by mebendazole in refractory metastatic colon cancer. Acta Oncologica. 2014;53:427–428. Single patient; response description summarized in the attached review.
16. Sinsuwan W, Norchai P. Repurposing drugs in controlling recurrent platinum-resistant clear-cell ovarian cancer. Case Reports in Oncological Medicine. 2023:2079654. Multi-drug case report summarized in the review.
17. Lai Y et al. A review of ivermectin use in cancer patients. Acta Poloniae Pharmaceutica. 81:913–929. Tolerability compilation described in the attached review; not an anticancer efficacy trial.
18. ICONIC, NCT07487805. ClinicalTrials.gov. Registered ivermectin dose-comparison study with checkpoint inhibition; no mebendazole. Registry design is not a result.
19. The Wellness Company. Ivermectin + Mebendazole product page. Checked 30 October 2026. Commercial primary source documenting product sales and off-label consultation availability; not medical efficacy evidence.
20. NCT02366884: Atavistic chemotherapy. ClinicalTrials.gov. Sponsor: Dr. Frank Arguello Cancer Clinic. Registered protocol listing ivermectin and mebendazole among possible agents; no posted results. Checked 30 October 2026.
21. Frank Arguello. The Atavistic Chemotherapy Trial. Investigator-hosted case narratives. Not a peer-reviewed randomized results report; cited to distinguish patient stories from drug-specific trial evidence.