The first clinical trial of a gene therapy for an inherited cause of progressive blindness called choroideremia has shown promising initial results which have surpassed expectations of the Oxford University researchers leading the study.
The aim of the study was to get the gene therapy into the cells in the retina of the eye without causing damage. After six months, however, the patients actually showed improvements in their vision in dim light and two of the six were able to read more lines on the eye chart. A total of nine patients have now had one eye treated with the gene therapy in operations at the Oxford Eye Hospital, part of the Oxford University Hospitals NHS Trust. The therapy is given in one eye to allow comparison with progression of the disease in the other eye.
Professor Robert MacLaren of the Nuffield Laboratory of Ophthalmology at the University of Oxford led the development of the retinal gene therapy and this first clinical trial. He said: “It is still too early to know if the gene therapy treatment will last indefinitely, but we can say that the vision improvements have been maintained for as long as we have been following up the patients, which is two years in one case.”
He added: “The results showing improvement in vision in the first six patients confirm that the virus can deliver its DNA payload without causing significant damage to the retina. This has huge implications for anyone with a genetic retinal disease such as age-related macular degeneration or retinitis pigmentosa, because it has for the first time shown that gene therapy can be applied safely before the onset of vision loss.”
The clinical trial is funded by the Health Innovation Challenge Fund, a partnership between the Wellcome Trust and the Department of Health. Results at six months are now reported for the first six patients in The Lancet medical journal.
