Israeli researchers have made a surprising discovery, finding that sildenafil, the active ingredient in the erectile dysfunction drug Viagra, may help stop cancer from spreading. Scientists at the Weizmann Institute of Science, working with the U.S. National Cancer Institute and Clalit Health Services, uncovered a new biological pathway where sildenafil disrupts cancer cells' cholesterol supply. This cholesterol is vital for cancer cells to metastasize, or spread, to other organs. The peer-reviewed research, published in July in the journal Cancer Research, offers fresh hope for new cancer treatments.[timesofisrael+4]
How Sildenafil Blocks Cancer's Spread
The core of this new finding lies in how sildenafil impacts cholesterol within cancer cells. Researchers found that sildenafil, by blocking an enzyme called phosphodiesterase type 5, or PDE5, increases the levels of a signaling molecule known as cGMP. This cGMP then binds to a protein responsible for transporting cholesterol inside cells. This interference traps cholesterol within tiny sac-like organelles called lysosomes, making it unavailable for the cancer cells to use.[timesofisrael+4]
Cancer cells rely heavily on mobile cholesterol to detach from their original tumors, travel through the bloodstream, and invade distant organs. Without access to this crucial building block, the cancer cells lose their ability to spread effectively. This discovery highlights a previously unknown mechanism by which a commonly used drug could combat one of cancer's deadliest aspects: metastasis.[timesofisrael+4]
Combining Sildenafil with Statins
The research also explored how cancer cells respond when their cholesterol supply is disrupted. Scientists observed that when sildenafil kept mobile cholesterol away, cancer cells tried to compensate by activating systems to produce more cholesterol on their own. This led researchers to combine sildenafil with statins, a widely prescribed class of drugs known for lowering cholesterol by reducing its production in the body.[timesofisrael+1]
The combination of sildenafil and statins proved to be even more effective. Together, these drugs restricted cancer cells' access to existing cholesterol while also preventing them from creating new cholesterol. This dual action created a stronger anti-metastatic effect. Observational data collected over 20 years from approximately 5 million members of Clalit Health Services in Israel supported these laboratory findings. The data showed that survival rates were highest among patients who had taken both sildenafil and statins six months before their cancer diagnosis.[timesofisrael+5]
Professor Ayelet Erez, a lead researcher from the Weizmann Institute of Science, emphasized the significance of these findings. "We uncovered a new biological pathway and showed how this pathway can be harnessed," Erez told The Times of Israel.Laboratory tests focused on aggressive cancers like triple-negative breast cancer, melanoma, and lung cancer. The real-world patient data further confirmed these findings for lung, colon, and prostate cancer in male mice models.[timesofisrael+1]
Early Hope, Future Trials
While the findings are promising, researchers stress that this is early-stage research. The results are largely preclinical, based on laboratory studies in cell cultures and mouse models. Dr. Mike Lattanzi, a medical oncologist not involved in the study, cautioned that the findings, while intriguing, are not yet ready to change how patients are treated. "These results are preclinical—meaning the data were derived from cell lines or mice. They are intriguing and thought-provoking, but they would need to be validated in human studies in order to inform the management of cancer patients," Lattanzi told Newsweek.
The next critical step is to conduct human clinical trials to confirm if sildenafil, alone or in combination with statins, is safe and effective in preventing cancer spread in people. Professor Erez highlighted the urgency, stating, "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." Researchers also emphasize that patients should not begin taking Viagra to treat or prevent cancer without consulting their doctors.[newsweek+1]
Sildenafil is an attractive candidate for drug repurposing because its safety profile is already well-understood due to its decades of use for erectile dysfunction and pulmonary arterial hypertension. This knowledge can significantly speed up the development of new treatments, potentially saving years of research and development.[healthline+3]
Broader Anti-Cancer Research
The potential of sildenafil and similar drugs to fight cancer is not entirely new. Previous studies have explored phosphodiesterase-5 (PDE5) inhibitors' broader anti-cancer properties. These drugs have shown potential to suppress tumor growth, enhance immune responses, and improve the effectiveness of chemotherapy in various cancer types. For instance, some research suggests that PDE5 inhibitors can reduce postoperative metastasis and restore immune function after cancer surgery.
A Swedish study, for example, found that potency-enhancing PDE5 inhibitor drugs, including sildenafil, reduced the risk of colon cancer death by 18 percent in men and made colon cancer less likely to metastasize. This effect was potentially linked to regulating immunosuppressive pathways. Other research has also shown sildenafil enhancing the efficacy of chemotherapy drugs like doxorubicin in prostate cancer and regorafenib in advanced solid tumors, while also offering cardioprotective benefits, reducing damage to the heart caused by chemotherapy.[topics+4]
However, the effects can vary by cancer type. While many studies support beneficial or neutral effects, some research has raised concerns about a potential increase in melanoma risk with sildenafil use, suggesting that the drug's impact may depend on the specific tumor biology and patient characteristics. Despite these varied findings, the latest research from the Weizmann Institute offers a novel and specific mechanism, focusing on cholesterol disruption, that adds a new dimension to understanding sildenafil's potential in the fight against cancer.[masseycancercenter+6]
