Viagra (sildenafil) may block cancer metastasis in preclinical research

Researchers from the United States and Israel reported that sildenafil, the active ingredient in Viagra, can inhibit the spread of cancer cells in laboratory mouse models of breast, lung, colon and prostate tumors. The drug blocks the enzyme PDE5, raising intracellular cGMP, which binds to the cholesterol‑transport protein NPC1 and traps cholesterol inside lysosomes. Without cholesterol, cancer cells lose the energy and membrane dynamics needed for migration, leading to collapse of metastatic capability while sparing healthy cells.

The effect was amplified when sildenafil was combined with cholesterol‑lowering statins, further decreasing metastatic potential in the studies. The investigators emphasize that the findings are pre‑clinical and that human clinical trials are required before any change in cancer treatment protocols.

The study suggests a possible new therapeutic use for a widely prescribed medication, but experts caution that more research is needed to confirm safety and efficacy in patients.