In the U.S., there are more than 900 people ages 2 or older with one of these 23 residual function mutations, which result in partially functioning (or "residual functioning") CFTR protein at the cell surface. Ivacaftor is a type of CFTR modulator called a potentiator that increases activity of the CFTR protein at the cell surface and has been shown in studies to improve lung function.

The approval of these 23 mutations was based on a combination of laboratory results that suggest the benefit of ivacaftor for these mutations, clinical trial data, and the drug's established safety record.

"Today's announcement is wonderful news for those people who will now benefit from modulators, particularly for younger individuals whose early access to these transformative therapies could potentially mean a life free from the severe and progressive complications associated with cystic fibrosis," said Preston W. Campbell, M.D., president and CEO of the Cystic Fibrosis Foundation. "It also represents the results of the unwavering determination of the CF community in our pursuit of treatments for everyone with this disease, regardless of their mutation."

Vertex Pharmaceuticals Inc., the manufacturer of the drug, also indicated that it is continuing discussions with the FDA regarding the expansion of ivacaftor to people with five specific splice mutations. (Splice mutations occur when there is an alteration in the DNA sequence that inserts, deletes, or changes the instructions for making a CFTR protein.) In the U.S. there are more than 600 people ages 2 and older with one of these five mutations.

"The FDA's consideration of laboratory evidence coupled with clinical data to address the needs of people with CF who have less common mutations should be commended," said Michael Boyle, M.D., senior vice president of therapeutics development at the Cystic Fibrosis Foundation. "By using this approach, the FDA put the health of CF individuals with rare mutations first without compromising its high standards for safety or efficacy. We are also encouraged that the FDA is considering this same methodology to evaluate the use of ivacaftor to treat certain splice mutations, as there are currently no disease-modifying therapies that target these defects."

Ivacaftor was developed by Vertex with significant clinical, scientific, and financial support from the Cystic Fibrosis Foundation.

About Cystic Fibrosis Mutations

People with CF have two mutated copies of the CFTR gene -- one inherited from each parent. There are more than 1,700 mutations in the CFTR gene that cause CF.  

With today's announcement by the FDA, ivacaftor is approved to treat the following mutations:

Vertex is continuing discussions with the FDA regarding the potential approval of the five following splice mutations: 3849+10kbC->T, 2789+5G->A, 3272-26A->G, 711+3A->G, E831X.

For additional information regarding today's news, please see the announcements from the FDA and Vertex.