Transformative mutation specific pharmacotherapy for cystic fibrosis

Ever since the discovery of the cystic fibrosis transmembrane conductance regulator gene (CFTR) in 1989 explained the genetics and pathophysiology of cystic fibrosis,1 healthcare providers, patients, and parents have hoped that a CFTR based treatment would be discovered. The study by Ramsey and colleagues published in November 2011 is a crucial step towards fulfilling that hope.2

In conjunction with Vertex Pharmaceuticals, the Therapeutic Drug Network (TDN) of the US Cystic Fibrosis Foundation (CFF), and the European Cystic Fibrosis Society Clinical Trials Network, 63 cystic fibrosis centres conducted a phase III randomised double blind placebo controlled trial to evaluate the CFTR potentiator developed as VX-770 and then named ivacaftor.3 4 Over 48 weeks, the study assessed 161 patients with cystic fibrosis and at least one specific CFTR mutation (G551D) that decreases CFTR channel function at the cell surface. Ivacaftor is a small molecule that increases the time that activated CFTR channels are open to transmit chloride ions.3 Patients who received ivacaftor had no adverse effects but had a 10.6% absolute increase from baseline in pulmonary function (forced expiratory volume in one second; FEV₁)—the study’s primary end point, were 55% less likely to have a pulmonary exacerbation, scored better on the respiratory symptoms domain of the quality of life instrument, gained 2.7 kg more …