Merton Professor sees promise in clinical trial results

Thursday 16 January 2014

Bodley Fellow Professor Robert MacLaren has announced that the initial results of a first clinical trial of the technique he pioneered, retinal gene therapy, have surpassed expectations. The therapy treats choroideremia, a rare inherited cause of blindness that affects around 1 in 50,000 people - but the approach has relevance for other far more common causes of blindness such as retinitis pigmentosa and age-related macular degeneration.

The aim of the treatment in this study was to get the gene therapy into the cells in the retina of the eye without causing damage. After six months, however, the six patients actually showed improvements in their vision in dim light and two were able to read more lines on an 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.

Prof MacLaren 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.

"In truth, we did not expect to see such dramatic improvements in visual acuity ... 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."