The clinical trial for retinal gene therapy in patients with choroideremia, led by Professor Robert McLaren of the Nuffield Laboratory of Ophthalmology, was a successful breakthrough.
Choroideremia is a rare X-linked recessive disorder which causes progressive blindness due to the degeneration of the retina and the choroid of the eye. It is presumed to be caused by a mutation in the CHM gene located on the X chromosome which encodes the protein called REP1 (Rab escort protein 1). With the protein losing its function, the pigment cells in the retina stops functioning as well, causing blindness. There is currently no definitive cure for this condition.
The study involved the use of an AAV (adeno-associated virus) to carry the protein REP1. The genome particles (AAV.REP1) were injected in the subfoveal area of the eye. The objective of the innovative for nursing informatics field – gene therapy, is to incorporate the CHM gene into retina’s photoreceptors. Once delivered into the cells, the cells are expected to generate the missing protein, which is the REP1. This would prevent the cells from losing their functions.
The retina gene therapy was done in six patients with an age range of 35-63 years old. The subjects were then tested 6 months after surgery to assess visual acuity, microperimetry, and retinal sensitivity. The values were compared to their baselines.
The results of the trial and its complete details, which were published in The Lancet, show great promise in the treatment of choroideremia and other diseases of the eye such as macular degeneration. Professor MacLaren however stated that it is not yet certain how long the treatment will last but the improvements in vision so long have been far maintained during the time of their follow ups with the patients treated, that is 2 years each case. Furthermore, he stated that “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”.
http://www.eye.ox.ac.uk. (2014, January). Retrieved February 2, 2014, from Nuffield Laboratory of Ophthalmology: http://www.eye.ox.ac.uk/research/clinical-ophthalmology-research-group/press-releases-1/first-results-of-choroideremia-gene-therapy-trial-2014
MacLaren et al. (2014). Retinal gene therapy in patients with choroideremia: initial findings from a phase 1/2 clinical trial. The Lancet.