LOS ANGELES, May 14 (UPI) -- U.S. researchers say drugs approved to treat erectile dysfunction may help treat brain tumors.
Researchers at Cedars-Sinai Medical Center in Los Angeles found the erectile dysfunction drugs sildenafil -- Viagra -- and vardenafil -- Levitra -- inhibited the enzyme phosphodiesterase 5 -- increasing the permeability of the blood-brain barrier.
"Mother Nature created this barrier to protect our brains from dangerous substances, but here we need to get through the barrier to deliver the drugs," Dr. Julia Ljubimova says in a statement.
Ljubimova and colleagues linked giving vardenafil in mouse models to a two-fold increase in the amount of Herceptin -- an antibody used to treat lung and breast tumors positive for HER2/neu -- that reached the brain tumor. The vardenafil/Herceptin combination boosted mean survival by 20 percent, versus Herceptin alone.
The study, published in the journal PLoS ONE, also found mice with tumors that were not HER2-positive did not experience the same increase in survival with vardenafil/Herceptin as mice with HER2-positive tumors had.
"As we find new drugs that are able to target these tumor cells, it is imperative that we develop better ways to enable the medications to reach their targets," senior author Dr. Keith Black said.
