Doctors excited by cystic fibrosis therapy
A therapy that corrects the underlying cause of cystic fibrosis could transform treatment, doctors have said.
Only half of people with cystic fibrosis make it into their 40s.
Defects in their DNA mean they produce thick, sticky mucus that clogs and inexorably damages their lungs.
Data presented at the North American Cystic Fibrosis Conference shows that a drugs combination - which enables production of runnier mucus - slows the irreversible decline in lung function.
Errors in people's DNA - or genetic code - can lead to defective microscopic machinery in the lungs.
Instead of producing a normal protective layer of mucus, they get the balance of salt and water wrong and it becomes damaging.
Antibiotics help prevent infections settling in and drugs can loosen the mucus, but nothing deals with the fundamental problem for most patients.
Early studies had suggested the drugs lumacaftor and ivacaftor could alter the microscopic machinery so they made runnier mucus.
Those studies followed patients for just 24 weeks, but now doctors have nearly two years of data on them.
The drug combination is clearly not a cure, but the researchers said the untreated patients would expect their lung function to decline by 2.3% a year, but this fell to 1.3% in those given the therapy.
They were also less likely to need hospital treatment.
Dr Michael Konstan, who led the trial from the Case Western Reserve University School of Medicine, said: "These data suggest that the benefits of lumacaftor/ivacaftor are sustained and indicate that the medicine may modify the progression of cystic fibrosis lung disease by treating its underlying cause."
Dr Stuart Elborn, from the Royal Brompton Hospital in London where some of the patients were treated, told the BBC News website: "This is an incremental advance rather than a breakthrough, but it is very reassuring that the effect does not wear off.
"I'm really excited by the therapy and also the pipeline of other powerful drugs that could get us closer to a cure."
The therapy is not available on the NHS after it was rejected by funding bodies in England and Scotland.
It costs more than £100,000 a year for each patient.
There are also many types of error in the DNA that can culminate in cystic fibrosis.
This treatment combination should work on around half of patients, while one of the drugs on its own corrects a small proportion of errors.
New treatments are still required for the remaining patients.
One in every 2,500 babies in the UK has cystic fibrosis.
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