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Phase III Drug Trial Shows Significant Lung Function Improvement in Genetic Subset of Cystic Fibrosis Patients
A new study has confirmed that the drug, ivacaftor, significantly improves lung function in some people with cystic fibrosis (CF). The results of the phase III clinical trial study, "A CFTR Potentiator in Patients with Cystic Fibrosis and the G551D Mutation," led by Dr. Bonnie W. Ramsey of Seattle Children's Research Institute and the University of Washington, were published in the November 3, 2011 issue of the New England Journal of Medicine. Ivacaftor, also known as VX-770, was developed by Vertex Pharmaceuticals with financial support from the Cystic Fibrosis Foundation. The oral medicine targets the defective protein produced by the gene mutation called G551D that can cause CF. Researchers found that CF patients carrying the G551D mutation – approximately four per cent of all CF patients – who were treated with VX-770 showed a 17 per cent relative improvement in lung function that was sustained over the course of 48 weeks. Additionally, patients with G551D treated with VX-770 showed improvements in other areas critically important to the health of people with CF. Study participants experienced significant reductions in sweat chloride levels indicating an improvement in the body's ability to carry salt in and out of cells – a process, which when defective, leads to CF. They also experienced decreased respiratory distress symptoms and improved weight gain. Those who received VX-770 gained on average seven pounds compared to those in the placebo group who gained approximately one pound. This is significant because many people with CF have difficulty gaining and maintaining weight due to reduced lung function and chronic infection. "Our study shows that we are now able to improve the quality of life for cystic fibrosis patients with the G551D mutation with the administration of VX-770," said Dr.