Gene therapy has been used successfully to improve the vision of six patients who would otherwise be blind.
Use of the technique on a patient was first reported in 2011 (see previous news), leading to a larger clinical trial of six patients.
The patients suffer from choroideremia, a genetic condition that causes gradual deterioration of the results in the retinal eye cells, resulting in progressive loss of sight. The condition is caused by defects in the CHM gene on the X-chromosome, which encodes RAB Escort Protein-1 (REP-1).
They received a viral gene therapy vector containing healthy copies of the CHM gene delivered directly to the eye. The purpose of this initial trial was to establish safety of the technique and hopefully arrest further deterioration of the patients’ vision, but six months after treatment, all patients showed some improvement in their vision and two had significantly improved vision.
Surgeon Prof Robert MacLaren of the University of Oxford Nuffield Laboratory of Opthalmology, who led the trial, said: "We really couldn't have asked for a better result". He also expressed hope that the success could pave the way for effective gene therapy for other forms of blindness with a genetic basis, possibly including age-related macular degeneration.
A second-phase clinical trial is now planned to further evaluate the technique.