Weizmann study finds Viagra's active drug may curb cancer's spread

On 21 July 2026 the Weizmann Institute of Science reported a study, published in the journal Cancer Research, suggesting that sildenafil, the active ingredient in Viagra, may help limit metastasis, the spread of cancer that causes most cancer deaths. The research was led by Dr Yarden Ariav in the laboratory of Professor Ayelet Erez, in collaboration with Professor Eytan Ruppin's group at the US National Cancer Institute, the innovation division of Clalit Health Services and physicians at Rabin Medical Center.

Sildenafil works by blocking an enzyme called PDE5, which raises the level of a signalling molecule, cGMP. Erez's team discovered that cGMP has an unexpected second job: it binds to a protein that moves cholesterol around inside cells. When cGMP rises, less cholesterol reaches the places where cells need it. Cancer cells, which depend heavily on cholesterol to grow and travel, turned out to be especially sensitive, and in mice they formed fewer metastases.

The researchers also found the cancer cells' escape route: deprived of cholesterol from outside, they try to make their own. Statins, the common cholesterol-lowering drugs, block that internal production. In laboratory experiments, combining a sildenafil-type drug with a statin was far more effective than either alone.

To see whether the effect might show up in people, the team analysed 20 years of anonymised records covering about five million members of Clalit, Israel's largest health provider. Cancer patients who had taken sildenafil had significantly better survival, particularly if they also took statins. Because this is observational data, it shows an association rather than proof, and the authors stress that clinical trials are needed before the drugs could be recommended for cancer.

Both drugs are cheap, widely used and well understood, which could make such trials quicker to run than trials of entirely new medicines.