People with an uncommon form of cystic fibrosis started gaining weight and were better able to breathe than their untreated counterparts after just two weeks on an experimental drug, according to a study published November 2 in The New England Journal of Medicine. If approved by the U.S. Food and Drug Administration, the drug, once known as VX-770 and now called ivacaftor, would be the first medication to target the underlying protein defect that causes the disease.

The findings are particularly compelling because the drug's benefits lasted for the duration of the 48-week randomized double-blind, placebo-controlled trial (the most rigorous type of scientific investigation that can be conducted).

In addition, clinicians have long known that cystic fibrosis patients with stable lung function who do not lose weight are more likely to live longer. That does not necessarily prove that ivacaftor can improve lifespan, but the possibility is tantalizing. "I've been involved in clinical trials for 30 years," says the study's lead author Bonnie Ramsey, a professor of pediatrics at the University of Washington School of Medicine in Seattle. "I've never seen this kind of change that has been sustained this long."

An estimated 70,000 individuals around the globe suffer from cystic fibrosis (CF), which interferes with the normal function of the respiratory and digestive systems. The particular protein defect that the drug is designed to counteract affects about 5 percent of all CF patients. With good preventive care and treatment, the majority of all CF patients are able to live to their late 30s or early 40s.

To learn more, read Scientific American’s feature "A Breath of Fresh Air" (preview), about the research behind ivacaftor and several other compounds that may someday address more common forms of cystic fibrosis.