A team of Israeli scientists reports that sildenafil, the active ingredient in Viagra, interferes with cancer cells’ ability to obtain cholesterol, a process the researchers say is essential for metastatic spread. The findings, published in the journal Cancer Research, draw on experiments in animal models and cell cultures, together with a two-decade analysis of health records from about 5 million members of Israel’s Clalit Health Services.
Laboratory results and real‑world data
The multi‑institutional effort was led by researchers at the Weizmann Institute of Science and included collaborators from the U.S. National Cancer Institute, Clalit’s Innovation Division and Rabin Medical Center. In laboratory studies, investigators examined mouse cancer models and human cancer cell cultures — focusing in particular on aggressive subtypes such as triple‑negative breast cancer, melanoma and lung cancer — to trace how sildenafil affects intracellular cholesterol handling.
In those tests, researchers report that sildenafil caused cholesterol to be sequestered within lysosome‑like structures, making it less available to cancer cells. The team linked this disruption of cholesterol trafficking to reductions in the cells’ ability to migrate and invade, processes central to metastasis.
Complementing the bench science, the group analysed clinical data spanning roughly 20 years from Clalit members. They found that survival outcomes were best among patients who had been prescribed both sildenafil and a statin within the six months prior to a cancer diagnosis.
"The uniqueness and the most important thing that we now need to do is a clinical trial to give Viagra to women with triple‑negative breast cancer," the senior investigator said.
Implications and next steps
The investigators caution that these results do not by themselves establish that sildenafil should be used as cancer therapy. They emphasise that human clinical trials will be required to test safety, dosing and efficacy for oncologic indications, including in women with triple‑negative breast cancer — a subtype that lacks targeted hormonal therapies and often has a poorer prognosis.
The team also reported an apparent interaction with statins, a class of cholesterol‑lowering medicines. According to the researchers, patients exposed to both sildenafil and statins before diagnosis showed the most favourable survival patterns in the retrospective health‑record analysis.
- Experimental models: mouse cancer models and human cell cultures demonstrated impaired cholesterol access in cancer cells.
- Population data: analysis of roughly 5 million members of a national healthcare provider over 20 years.
- Notable finding: combined prior use of sildenafil and statins correlated with higher survival among patients in the dataset.
| Evidence source | Role in study |
|---|---|
| Mouse cancer models | Demonstrated effects on metastasis‑related behaviour |
| Human cancer cell cultures | Revealed cholesterol sequestration in lysosome‑like structures |
| Clalit health records (~5 million members) | Provided observational survival associations with drug exposure |
Caveats and scientific context
Experts not involved in the study generally regard laboratory findings and observational record analyses as important early steps, but warn that they cannot substitute for randomised controlled trials. Observational associations can be influenced by confounding factors, prescribing patterns, comorbidities and other unmeasured differences between patient groups.
The research team appears aware of these limitations and has explicitly called for clinical trials to test whether repurposing sildenafil for oncology is both safe and beneficial. If trials confirm a therapeutic effect, the finding would point to a novel strategy for limiting metastasis by targeting tumour lipid handling rather than directly attacking cell proliferation.
The prospect of repurposing an established drug carries practical advantages: sildenafil is widely used, its side‑effect profile is well characterised, and manufacturing and distribution channels already exist. Nevertheless, translating the present findings into approved cancer treatments would require rigorous testing through the standard clinical‑trial pathway.
The study underscores growing scientific interest in the metabolic and microenvironmental factors that enable cancer spread — and in whether existing pharmaceuticals can be redeployed to exploit those vulnerabilities.
