Personalized Medicine in Cystic Fibrosis Dawning of a New Era

Life expectancy in cystic fibrosis (CF) has improved substantially over the last 75 years, with a median predicted survival now approaching 40 years. This improvement has resulted largely from therapies treating end-organ manifestations. In an effort to develop drugs that would target the underlying defects in the CF transmembrane conductance regulator (CFTR), the Cystic Fibrosis Foundation embarked on a bold initiative in which it established collaborations with biopharmaceutical companies to support early-stage efforts to discover new medicines for CF. This has led to the development and clinical trial testing of several novel drugs targeting specific CFTR mutations. One drug, ivacaftor, was recently approved by the US Food and Drug Administration for the approximately 4% of patients with CF who have the G551D gating mutation. Drugs targeting F508del CFTR and premature termination codons, which would be applicable to 90% of patients with CF, are undergoing clinical trials. The impact of such drugs on CFTR biomarkers, such as sweat chloride and nasal potential difference, suggests that they may reset the clinical trajectory of CF, but their effect on long-term outcomes will remain unknown for many years. Nevertheless, development of CFTR-targeted drugs represents an important milestone in CF, perhaps revolutionizing the care of these patients in a fundamental way.