A new drug has been found to improve lung function and help patients with a specific type of cystic fibrosis to gain weight and otherwise fight the disease, research reveals.

The study, published this week in the New England Journal of Medicine, followed 167 people for one year, all of whom were over the age of 12 and had cystic fibrosis. Those taking the drug ivacaftor saw improvements within two weeks: they could blow 10 percent more air from their lungs, gained an average of 6 pounds, and were 55 percent less likely to experience sudden, serious flare-ups of their condition, as compared to those not taking the drug. The effects lasted the duration of the study.

Ivacaftor works for people with the G551D mutation of the disease, said Dr.
Michael Konstan, M.D., one of the study's authors and chair of pediatrics at Rainbow Babies and Children Hospital in Cleveland.

Although just 4 percent of people with cystic fibrosis have this mutation, Dr. Konstan says the drug is still considered a breakthrough: "This is the first time that we have a therapy that is directed at the cause of cystic fibrosis,"

Cystic fibrosis is a hereditary disease in which mucus clogs the lungs and liver and can cause digestive problems. According to the Cystic Fibrosis Foundation, about 1,000 new cases are diagnosed each year, and most people with the condition die by the age of 40. There currently is no cure.

Vertex Pharmaceuticals partially funded the study.

Ivacaftor has been submitted to the Food and Drug Administration for approval, and may be widely available as early as next year, Dr. Konstan said.