Vertex Pharmaceuticals' Kalydeco plus lumacaftor combination treatment for cystic fibrosis (CF) met its endpoint in two phase 3 trials. Although the gains were modest, lung function improved 2–4% over patients taking placebo, experts agree that they are important. The combination treatment addresses people with the most common form of CF, those with a homozygous mutation in delta F508 CF transmembrane conductance regulator (CFTR). The approved Kalydeco (ivacaftor) alone targets the G511D mutation, affecting only 1,200 patients in the US, but when given with lumacaftor (VX-809), could reach over 22,000 patients in North America, Europe and Australia. Vertex plans to submit a new drug application to the US Food and Drug Administration and a marketing authorization application to the European Medicines Agency by the end of the year.