Drugs sometimes have beneficial side effects. A glaucoma treatment causes luscious eyelashes. A blood pressure drug also aids those with a rare genetic disease. The newest surprise discovered by researchers at the Johns Hopkins University School of Medicine is a gonorrhea medication that might help battle cancer.

"Often times we are surprised that a drug known to do something else has another hidden property," says Jun Liu, Ph.D., a professor of pharmacology and molecular sciences at Johns Hopkins and author on the study published Oct. 1 in the Proceedings of the National Academy of Sciences.

In this case, the surprise is a big one. The drug, acriflavine, used in the 1930s for treating gonorrhea, has turned out to have the previously unknown ability to halt the growth of new blood vessels. Preliminary tests showed that mice engineered to develop cancer had no tumor growth if treated with daily injections of acriflavine.

"As cancer cells rapidly divide, they consume considerable amounts of oxygen," says Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Pediatrics and director of the vascular program at the Johns Hopkins Institute for Cell Engineering…