Trial participants receive the gene therapy by inhaling fat globules containing the corrective DNA.
Image credit: Imperial College London
The trial - run by the UK Cystic Fibrosis Gene Therapy Consortium - now needs to be followed by further studies to assess the optimum dose and treatment schedule, they add.
The placebo-controlled, double-blind trial was carried out at two centers in the UK and recruited 136 cystic fibrosis patients over the age of 12.
The patients received either monthly doses of the gene therapy or a placebo for 1 year.
The trial tested a gene therapy where the patient inhales molecules of DNA wrapped in fat globules (liposomes) that deliver a correct copy of the gene into the cells in the lung lining.
Cystic fibrosis is a condition where the lungs produce too much thick mucus, making breathing difficult and increasing the risk of infection.
The disease is caused by a single faulty gene located on chromosome 7.
Gene therapy shows 'significant but modest' benefit
After 1 year of treatment, compared with placebo, patients who received the gene therapy showed "a significant, albeit modest, benefit" in forced expiratory volume or FEV in 1 second (a measure of lung function), write the study investigators, who note that such a result indicates a "stabilization of lung function in the treatment group."
They conclude the trial is the first to show that repeated doses of gene therapy can have a meaningful effect on cystic fibrosis and change lung function.
However, they warn there is still some work to do before the treatment is ready for clinical use. The effectiveness needs to be improved and the correct dosing needs to be established.
Lead author Eric Alton, a professor of gene therapy and respiratory medicine at Imperial College London, and consultant physician at Royal Brompton Hospital, is the coordinator of the Consortium. He adds that the findings also showed there were no safety concerns about the therapy, and:
"Whilst the effect was inconsistent, with some patients responding better than others, the results are encouraging, laying the groundwork for further trials, which we hope could improve the effect."
"We are looking to undertake follow-up studies assessing higher, more frequent doses as well as combinations with other treatments," he adds.
'Step change' in treatment of cystic fibrosis
Prof. Alton explains that by focusing on the basic defect underlying the disease rather than just its symptoms, they aim to bring about a "step change" in the treatment of cystic fibrosis:
"It has taken more than 20 years to get where we are now, and there is still some way to go. Eventually we hope gene therapy will push CF patients towards a normal life expectancy and improve their quality of life significantly."
Funding for the trial came from a partnership between the Medical Research Council (MRC) and the National Institute for Health Research (NIHR).
The Consortium is also developing a second therapy that uses a virus to deliver the corrective DNA to the lung cells. First clinical trials are expected to start in 2016.
Publication of the trial results follows other welcoming news that Medical News Today reported recently of a new drug combination that targets the most common genetic cause of the disease could extend the life of cystic fibrosis patients.
The trial results showed that treatment with a combination of lumacaftor and ivacaftor led to a reduction in required hospital antibiotic courses, and other improvements.