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Initial results from two gene therapy trials to treat a rare congenital eye disorder are extremely encouraging, producing a significant improvement in retinal function, particularly in one of the six patients (reported by BBC News).

 

The first trial started one year ago at London's Moorfields Eye Hospital and University College London (see previous news story). Functional copies of the RPE65 gene were injected into the retina of three young adults with Leber's congenital amaurosis, a rare form of inherited childhood blindness caused by mutations in the RPE65 gene leading to abnormal detection of light by the retina, for which there is currently no treatment. The results, published in the New England Journal of Medicine [Bainbridge JWB et al. (2008) NEJM, doi: 10.1056/NEJMoa0802268], indicate that the technique is safe and potentially enormously beneficial; although the treatment had limited effect on two of the subjects, one patient experienced a significant improvement in visual performance, particularly in low light, despite previously having advanced retinal degeneration.

 

The results of this trial are published back-to-back with the results of a second, more recent trial carried out on another three patients at the Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine [Maguire AM et al. (2008) NEJM, doi: 10.1056/NEJMoa0802315]. Just six months on, all three patients showed evidence of improved retinal function.

 

Comment: Although individually rare, there are over 70 groups of genetic conditions affecting the eye and processes of vision and around 1500 people each year in the UK will be affected by these disorders. National statistics and surveys show that each year in the UK, about 400 people will be diagnosed as blind or severely visually impaired as the result of an inherited (genetic) disorder. Genetic factors are also involved in common eye diseases that can lead to blindness, such as age-related macular degeneration (‘AMD’), glaucoma and cataract. These results provide some of the first clinical evidence that gene therapy might achieve its elusive promise of safe and effective treatments for genetic diseases. It is also worth noting that even modest improvements in visual function can have a marked effect on the quality of life for patients.

 

With increasing ability now to diagnose these conditions using genetic tests, coupled with the development of new targeted treatments such as gene therapy, which are based on a detailed molecular understanding of the conditions, it is now more important than ever that patients are managed in specialised services. With this in mind, the PHG Foundation has been working with key stakeholders on a Genetics in ophthalmology project, commissioned by the UK Genetic Testing Network (UKGTN). The new report, Genetic Ophthalmology in Focus, which will be released next week, sets out the findings of an expert working group on how NHS ophthalmology services need to adapt to take advantage of the opportunities offered by genetic science.