Vertex Pharmaceuticals has a number of ongoing clinical trials investigating the use of Ivacaftor in cystic fibrosis patients with mutations in the gene coding for cystic fibrosis transmembrane conductance regulator (CFTR). Two of its Phase III trials, which are studying patients homozygous for the F508del-CFTR mutation, recently switched the primary and secondary endpoints. TRAFFIC and TRANSPORT are still evaluating the efficacy and safety of Lumacaftor in combination with Ivacaftor (tradename Kalydeco), but the primary outcome measure is now “an absolute change in percent predicted forced expiratory volume in one second (FEV1).” The original primary endpoint was a relative change in lung function but is now a secondary endpoint.
The switch was made as “part of ongoing discussions with the FDA and was not based on anything going on in the study or anything observed in the study,” said Zach Barber, spokesman for Vertex.
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Both studies have three treatment arms. The first treatment arm is receiving 600 mg of lumacaftor daily and 250 mg of ivacaftor every 12 hours, the second is receiving 400 mg of lumacaftor and 250 mg of ivacaftor every 12 hours, and the third is receiving placebo throughout the 24-week period. The study began in March 2013, and completion is expected in April 2014. Results of these studies have the potential to generate $6 billion in new sales for Vertex.
Cystic fibrosis affects the lungs and digestive system, and the Cystic Fibrosis Foundation reports that 30,000 children and adults in the United States have the inherited chronic disease. Mutations in the CFTR gene lead to a defective protein that causes a buildup of thick, sticky mucus in the lungs and intestines, causing life-threatening lung infections and poor pancreatic enzyme activity to break down food. The drug Ivacaftor has been approved by the Food and Drug Administration since January 2012 for some subsets of cystic fibrosis patients. It improves the transport of chloride ions through CFTR by increasing the number of open channels.