The results of a phase IIII clinical study confirm that the drug ivacaftor (VX-770) significantly improves lung function in some cystic fibrosis (CF) patients. The oral medicine targets the defective protein produced by the G551D gene mutation that causes CF. The study, lead by researchers at Seattle Children’s Research Institute, appear in the New England Journal of Medicine.

Researchers found that patients carrying G551D—approximately 4% of all CF patients—who were treated with VX-770 showed a 17% relative improvement in lung function that was sustained over the course of 48 weeks. Additionally, patients treated with G551D treated with VX-770 showed improvements in other areas critically important to the health of people with CF, including significant reductions in sweat chloride levels, decreased respiratory distress symptoms, and improved weight gain. Those who received VX-770 gained on average 7 pounds compared to those in the placebo group who gained approximately 1 pound. The finding is significant as many people with CF have difficulty gaining and maintaining weight due to reduced lung function and chronic infection.

For the study, researchers evaluated lung function in patients 12 years or older who carry at least one copy of the G551D mutation. The study included 161 patients at multiple health care centers who received at least one dose of VX-770 or placebo. The study is the third and final in a series designed to assess the effectiveness and safety of VX-770 before it is approved for public use.

VX-770 was developed by Vertex Pharmaceuticals with financial support from the Cystic Fibrosis Foundation.

Source: Seattle Children’s Research Institute