Results from two phase 3 clinical trials published today in the New England Journal of Medicine show that a new combination of medications can successfully treat the underlying cause of cystic fibrosis for patients age 12 and older with two copies of the F508del gene mutation -- the most common form of the life-threatening, genetic disease found in over half of the cystic fibrosis (CF) population. Approximately 8,500 people in the U.S., and 22,000 people in North America, Europe and Australia, age 12 and older with cystic fibrosis carry this gene mutation.

The international trial, which studied more than 1,000 cystic fibrosis patients age 12 and older, revealed that a combination of the drugs Kalydeco (ivacaftor) and lumacaftor, an experimental drug that has not yet been approved by the Food and Drug Administration (FDA), successfully treated the defective CF protein and improved lung function. The drugs also helped patients achieve a 40 percent reduction in pulmonary exacerbations, the leading cause of death in cystic fibrosis patients.

"Being able to treat not just the symptoms, but the underlying cause of cystic fibrosis by targeting this specific gene mutation, is a major game changer because it is by far the most common in patients with this disease," said Dr. Bonnie Ramsey, director of the Center for Clinical and Translational Research at Seattle Children's Research Institute and professor of Pediatrics at the University of Washington, who presented the study's findings at the Center for Drug Evaluation and Research advisory committee meeting on May 12. "Previously, we found that Kalydeco treated just four percent of cystic fibrosis patients, but this new combination treats the defective CF protein for a much greater number of patients."

The drugs, which work together to address the defective gene mutation by allowing the proteins within the cell to fold properly, reach the cell surface and then work as a salt channel, were given to patients over the course of 24 weeks in an effort to gain insight on how they may improve lung function and quality of life for people living with cystic fibrosis.

The trial included cystic fibrosis patients from Seattle Children's and the University of Washington Medical Center. Today, the median predicted age of death for a person with the disease is in the mid-20s.

"What gives me tremendous confidence and excites me the most are the comprehensive health improvements seen in patients across all age groups, in all geographies and with all levels of disease severity," said Ramsey, who was one of four lead authors on the trial and is a pioneer in cystic fibrosis treatment. "Patients can now have longer periods of good health, greatly improving their quality of life."

The new combination of medications is up for FDA approval in July. If approved, Ramsey and her colleagues will be able to prescribe ivacaftor/lumacaftor to patients age 12 and older with F508del/F508del mutation. There are ongoing safety studies of the drug combination in children 11 years old and younger. These studies are being conducted at sites in the CF Therapeutics Development Network, which is coordinated by Seattle Children's.