The US Food and Drug Administration has given the green light to Vertex Pharmaceuticals' Kalydeco  for the treatment of a rare form of cystic fibrosis.

The approval covers patients aged six and older who have the specific G551D mutation in the cystic fibrosis transmembrane regulator gene. The thumbs-up comes well ahead of the proposed action date for Kalydeco ((ivacaftor), April 18, indeed after only a three-month review, and is based on data from two 48-week studies involving 213 patients with CF which showed that treatment with the drug "resulted in significant and sustained improvement in lung function", the FDA said.

CF affects about 30,000 people in the USA and is the most common fatal genetic disease in the Caucasian population. About 4% of those are believed to have the G551D mutation.

FDA Commissioner Margaret Hamburg said Kalydeco is "an excellent example of the promise of personalised medicine". She added that “the unique and mutually beneficial partnership that led to the approval of Kalydeco serves as a great model for what companies and patient groups can achieve if they collaborate on drug development".

The drug was discovered as part of a collaboration between Vertex and Cystic Fibrosis Foundation Therapeutics, the nonprofit drug discovery and development affiliate of the Cystic Fibrosis Foundation.

Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, said that Kalydeco, a pill taken two times a day with fat-containing food, is "a breakthrough therapy for the CF community because current therapies only treat the symptoms of this genetic disease".

It does not come cheap, however, as Vertex is pricing the drug at $294,000 annually. However, the firm will provide Kalydeco for free to people who do not have insurance and have an annual household income of $150,000 or less and for certain other patients, it will help cover co-pay or co-insurance costs up to 30% of the price.