A controversial real-world study reports striking outcomes from repurposed antiparasitic drugs—raising difficult questions about incentives, silence, and who benefits from the status quo.
A recent observational study hosted on Zenodo has reignited debate around drug repurposing in oncology—specifically the use of ivermectin and mebendazole in cancer patients. While not a randomized controlled trial, the reported outcomes are difficult to ignore and are prompting renewed scrutiny of how—and why—certain therapies gain traction while others stall.
The study, “Ivermectin and Mebendazole in Cancer Patients” followed 197 participants prescribed the combination protocol via licensed U.S. telemedicine providers. At six months, 122 patients completed follow-up, revealing a Clinical Benefit Ratio (CBR) of 84.4%, defined as complete response, partial response, or stable disease. Notably, 48.4% of patients reported tumour regression or no evidence of disease (NED)—figures that, if validated, would be highly significant in oncology research.
The cohort was heterogeneous, including prostate, breast, lung, colon, and other cancers, with 37.1% experiencing active disease progression at baseline. Despite this, outcomes showed 36.1% disease stability and only 15.6% progression at follow-up. Adherence was high (86.9%), and side effects were predominantly mild and manageable .
Mechanistically, both drugs have documented anti-cancer properties. Ivermectin has demonstrated multiple anti-tumour pathways, including inhibition of proliferation, angiogenesis, and metastasis, while mebendazole disrupts microtubules and induces apoptosis . Combined, they appear to target complementary pathways, potentially producing synergistic effects observed in preclinical models.
The implications are obvious—and uncomfortable. These drugs are off-patent, inexpensive, and widely available. In contrast, conventional cancer therapies can cost upwards of $111,000 annually per patient . This disparity raises an unavoidable question: what incentive exists to rigorously pursue therapies that cannot be exclusively monetized?
The pharmaceutical industry, led by companies such as Pfizer, Roche, and Merck & Co., operates within a framework where patent protection underpins research investment. Developing a new drug can exceed $1 billion, a cost justified by the temporary monopoly granted through patents. Repurposed drugs, by contrast, offer little opportunity for exclusivity, making large-scale trials financially unattractive.
This creates what some researchers describe as a “funding gap” in repurposed medicine. A 2021 review in Nature Reviews Drug Discovery noted that while drug repurposing holds promise, it is often underfunded due to lack of commercial incentive . Similarly, the World Health Organization has acknowledged the need for alternative funding models to support non-commercial therapeutic research.
Critics argue that this dynamic can lead not to overt suppression, but to a more subtle outcome: neglect. Without major funding, promising signals remain untested in large randomized trials—the gold standard required for regulatory approval and clinical adoption. As a result, therapies may exist in a liminal space: visible enough to provoke interest, but unsupported enough to be dismissed.
To be clear, the Zenodo study itself acknowledges its limitations: observational design, self-reported outcomes, and potential bias mean the findings are hypothesis-generating, not definitive . No serious clinician would argue for immediate clinical adoption based on this data alone. The authors themselves call for urgent randomized, placebo-controlled trials.
But here lies the tension. If such trials are unlikely to be funded by industry, and public funding is limited or slow-moving, who carries the responsibility to investigate?
The question is no longer purely scientific. It is structural.
When a low-cost intervention shows signals of benefit, yet lacks a commercial pathway, the system faces a conflict between economic incentive and clinical curiosity. Whether this results in active suppression or passive neglect is debated. What is harder to dispute is that the current model is not designed to prioritise such therapies.
And that, perhaps, is the most provocative finding of all.
Read the paper here: https://zenodo.org/records/19455636