Potential new treatment for cystic fibrosis

10 September 2008

Preliminary results suggest that a new drug may be an effective treatment for cystic fibrosis, which affects some 70,000 people worldwide and is one of the most common single-gene disorders in the UK, with around 8000 sufferers. One in 25 Caucasians are carriers of causative mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene, which impair chloride transport in cells; the disease occurs in people who inherit two such mutations. Characterised by excessive production of mucus and loss of salt via sweat, CF can cause significant respiratory and gastrointestinal problems, and markedly reduces life expectancy even in developed countries; there is as yet no treatment beyond interventions to reduce the symptoms, although there are ongoing efforts to develop gene therapies to cure the disease (see previous news).

The new drug VX-770 was developed by the Cystic Fibrosis Foundation in collaboration with Vertex Pharmaceuticals; it targets the defective CFTR protein to improve chloride transport. The Cystic Fibrosis Trust supports a group at the University of Bristol in investigating how new drugs restore function to defective CFTR proteins; group leader Dr David Sheppard reported results at the BA Festival of Science indicating that the new drug could cause a near 50% reduction in salt levels in sweat and a 10% improvement in lung function in cystic fibrosis patients. He said: “The early results with VX-770 suggest that drug therapies which target defects at the root of the disease have the potential to improve greatly the quality of life of CF patients” (see press release).

Of note, there are well over a thousand different mutations in the CFTR gene known to cause cystic fibrosis; this new therapy targets a particular type of mutation and would therefore be appropriate for only a small proportion of people with the disease, reportedly around 6% of UK patients (see BBC news). Moreover, not only are the reported results preliminary, requiring further trials to generate reliable data, but the drug offers only a potential alleviation of symptoms and not a cure. However, if effective this sort of treatment could significantly improve the quality and expectancy of life for CF patients, and it illustrates well how determining the genetic basis of disease can lead to an understanding of the underlying disease process, and hence to possible therapeutic interventions.

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