CF is caused by gene mutations that result in deficient or dysfunctional transmembrane conductance regulator (CFTR) protein, an anion channel that is normally present in the epithelial membrane. Two FDA- approved drugs may provide new options for at least some CF patients. Ivacaftor (Kalydeco) is a CFTR protein potentiator that increases the probability that the CFTR channels are open in vitro and improves clinical outcomes in patients ≥12 years of age with at least one copy of G551D mutation, present in ~5% of CF patients (1). 

Orkambi is a combination of ivacaftor and lumacaftor – a drug that prevents intracellular destruction of CFTR –for patients with the Phe508del CFTR mutation, present in ~50% of CF patients.   Its use has been associated with fewer pulmonary exacerbations and hospitalization in patients (≥ 6 years of age) homozygous for this gene (2). Ivacaftor and Orkambi are priced at over $300,000/year and $295,000/year, respectively (http://www.nytimes.com/2015/07/03/business/orkambi-a-new-cystic-fibrosis-drug-wins-fda-approval.html?_r=0).

1. Ramsey BW, Davies J, McElvaney NG, et al. A CFTR Potentiator in patients with cystic fibrosis and the G551D mutation. N Engl J Med 2011;365:1663-1672.

2. Wainwright CE, Elborn JS, Ramsey BW, et al. Lumacaftor-ivacaftor in patients with cystic fibrosis homozygous for Phe508del CFTR. N Engl J Med 2015;373:220-231.

Contributed by Cynthia M. Cooper, MD, Boston, MA