Personalised medicine for cystic fibrosis cleared in US

Vertex Pharmaceuticals has won approval in the US for Kalydeco, an oral therapy for a subset of cystic fibrosis (CF) patients that is the first therapy to target a specific genetic mutation in the disease.

Kalydeco (ivacaftor) has been approved to treat around 1,200 of the approximately 30,000 CF patients in the US whose disease is caused by a mutation in Cystic Fibrosis Transmembrane Regulator (CFTR) gene known as G551D.

The FDA said it approved the drug in just three months in recognition that Kalydeco is a true breakthrough in the treatment of this type of CF.

Vertex has said it will start shipping Kalydeco to US pharmacies this week, and will charge $294,000 per year for treatment with the drug.

CF is the most common fatal genetic disease to affect Caucasians and is characterised by a build-up of sticky mucus in the lungs and other organ systems, which can lead to infections and ultimately respiratory failure.

At the moment treatment is limited to physiotherapy to clear the lungs, sometimes with the help of an inhaled drug called Pulmozyme to break down the mucus, and supportive care such as antibiotics to treat infections.

Life expectancy for CF patients without a lung transplant is around 30-40 years of age.

In contrast, Kalydeco takes form of a tablet, taken twice a day with fatty food, which helps the CFTR gene function more effectively.  The drug interacts with CFTR protein channels, keeping them open for longer and improving the transport of salt and water across the cell membrane.

In trials involving people with CF who have at least one copy of the G551D mutation, Kalydeco demonstrated significant and sustained improvements in lung function, along with other disease measures such as weight gain, compared to placebo.

Those on Vertex' drug also experienced significantly fewer pulmonary exacerbations.

"The success of this approach will hopefully lead to the development of new medicines to address the more common mutations in CF," said Stephen Spielberg, deputy commissioner for medical products and tobacco at the FDA.

Research is ongoing to explore a similar targeted approach using a combination of two other medicines, used alongside Kalydeco, to treat the most common form of the disease, said Vertex.

Data from those trials could be available later this year, and analysts have suggested that approval in a broader CF population could generate franchise sales of $2-$3bn a year.

This is the second drug with blockbuster potential for which Vertex has won approval in the last 12 months. Last May it got authorisation for Incivek (telaprevir), an oral hepatitis C treatment tipped for multibillion sales at peak.