Research finds sildenafil may slow cancer spread

Viagra was originally developed to chest pains and high blood pressure that were caused by reduced blood flow to the heart. But during clinical trials the drug was found to be ineffective in this regard, and was instead more useful as a means of inducing erections. Since then, Viagra has had over three decades of use as the world’s best known prescription medication to combat erectile dysfunction.

And according to a new study from the Weizmann Institute of Science, Viagra may start being known for something else.

In a study published in the journal Cancer Research, scientists found that sildenafil may be able to disrupt the ability of cancer cells to receive cholesterol, a crucial material that allows them to spread to other organs. To understand how this works, it’s important to understand first how sildenafil functions.

Sildenafil blocks an enzyme known as phosphodiesterase type 5, or PDE5. When this enzyme is blocked, it increases the levels in the body of cyclic guanosine monophosphate, or cGMP. Higher cGMP levels in the body dilate blood vessels, thereby increasing blood flow, especially to the penis.

What the researchers found was that cGMP is also useful in binding to a protein responsible for transporting cholesterol within different groups of cells. And when cancer cells receive less cholesterol, they’re less likely to metastasize in other parts of the body. The researchers even highlighted the possibility that this could prevent cancer cells from producing their own cholesterol, thus further limiting their growth.

The researchers found that, when PDE5 inhibitors like sildenafil are combined with statins - drugs that reduce cholesterol production in the body - the restrictive effect on metastasis could be even more pronounced.

Researchers have highlighted the need for more research before definitively concluding whether PDE5 inhibitors could one day become part of regular cancer treatment. Such research should look into, among other things, whether or not sildenafil - and sildenafil combined with statins - would be more effective against certain types of cancers and whether this therapy could also help prevent the spread of cancer in women.

Given the nature of sildenafil - used primarily as an erectile dysfunction medication - researchers were unable to find sufficient statistical evidence to support sildenafil’s anti-cancer effects on women.

“Beyond their therapeutic promise, our findings highlight that cancer biology is shaped not only by mutations in tumor cells but also by the patient’s metabolic state and by medications they are already taking for other conditions,” said Ayelet Erez, whose team was responsible for the research.

“Our study underscores the importance of treating the whole patient - not just the cancer - when tailoring the most effective therapy.”