BPC 2008: Gene therapy problems in cystic fibrosis
Scientific developments in the treatment of cystic fibrosis and theirdelivery were the subject of a session at the British PharmaceuticalConference 2008. Benedict Lam reports
Scientific developments in the treatment of cystic fibrosis and their delivery were the subject of a session at the British Pharmaceutical Conference 2008. Benedict Lam reports
Lung gene therapy is hard because it goes against evolution, said Eric Alton, professor of gene therapy and respiratory medicine at Imperial College, London.
Professor Alton explained that cystic fibrosis is the most common lethal inherited disease in the UK. Patients develop thick, sticky secretions in the lungs, with repeated cycles of infections that gradually destroy them.
A median survival age of 35 years has only recently been achieved, mainly by good nutrition, physiotherapy to remove the sticky secretions and antibiotics to treat the infection.
The lungs of cystic fibrosis patients are gradually destroyed because the faulty cystic fibrosis transmembrane conductance regulator (CFTR) causes an incorrect volume of water to surround the cilia. This disrupts the clearance mechanism in the bronchiole’s membrane for mucus and pollutants from the lungs.
Professor Alton discussed the challenges of using gene therapy treatment for cystic fibrosis. Using the example of nebulisation of DNA, he explained that the immune system would simply destroy the DNA before it reaches its target. There are also problems with using viruses to deliver the normal CFTR gene into a patient. A single dose of gene therapy lasts a few weeks, meaning treatment is repetitive and life-long.
However, currently available viruses for gene therapy cannot be readministered continuously because the immune system would recognise the viruses and destroy them, along with the DNA. He added: “A few weeks of improving the [faulty] gene will not make patients better when they have had lung disease for many years.”
Although less efficient than viral gene therapy, a better method may be to use liposomes, which wrap up the DNA, fuse with the cell membrane and deposit the DNA into the patient. Professor Alton’s research team is currently working on gene therapy in this area.
Professor Alton believes conducting a multidose trial, where the dose is repeated every few weeks to measure improvement outcome, is the best method for researching gene therapy for cystic fibrosis patients. However, it requires a big effort from patients and researchers and will be of considerable cost.
For the trial to be viable, a large team of researchers is needed, hence the Cystic Fibrosis Trust brought together the three groups within the UK who are doing cystic fibrosis gene therapy clinical trials from Edinburgh, Oxford and London. Instead of working against one another, a team of 80 clinicians and scientists is currently working together with a common strategy.
Citation: The Salvadore URI: 10036122
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