Conventional treatments for CF include the use of physiotherapy, antibiotics and pancreatic supplements. Many patients require treatment four times daily, including a considerable time spent on physiotherapy. This combination of treatment has helped increase life expectancy considerably to the current median of approximately 30 years of age. Despite small further improvements, more recently it has become apparent that there is a need for a more effective and convenient therapy. The identification of the gene responsible for CF (the cystic fibrosis transmembrane conductance regulator or CFTR protein) in 1989, was responsible for the advent of potential new treatments for CF. Gene therapy, the transfer of a normal copy of the CFTR gene into the lungs of CF patients, was proposed as an attractive new option.
Only a year after the gene for CF was identified scientists showed in cells in the laboratory that it was possible to correct the CF defect by adding a healthy copy of the gene. These findings have been consistently repeated by other groups using a variety of models and gene transfer agents. Studies in humans followed quickly. Gene therapy for CF has been tested in humans using both viruses and liposomes. Five of the liposome trials were undertaken by members of the UK CF Gene Therapy Consortium. These early studies were concerned mainly with safety issues. The amount of gene transfer achieved is similar for both systems and is probably still too small to have any real therapeutic benefit - although it is important to note that none of these trials actually measured therapeutic benefit. Also at present the effect seen (gene expression) only lasts for a few days.
The scientific principle of gene therapy for CF is a sound one and the technology already exists to transfer the CF gene into the airway cells in man but there are still challenges ahead of the field. The two main challenges are getting the gene into the cells more efficiently and to make gene expression last longer. However the field is moving forward rapidly and with the development of better new viruses and liposomes these problems are surmountable.