Although we have been quiet on this website, we have been hard at work during the last three years! Our gene therapy trial wrapped up in September of last year and our results were just published online in the past month. As you may remember, this study investigated the safety and utility of gene therapy as a potential therapy for choroideremia. The goal of gene therapy is to reintroduce a functional copy of the CHM gene into the eye using a vector (or customized virus).
Our study included 6 participants aged 30-42 years who had a confirmed diagnosis of choroideremia. The viral vector which included the CHM gene was injected into the eye with worse vision of each participant. They were then followed over a 2-year period (Summer 2015-2017) with visual function testing every 6 months. The primary goal of the study was to determine whether the gene therapy was safe. The second goal was to measure any differences between the treated and untreated eye in each participant over time. We achieved both of these goals by measuring eye function and structure using different specialized testing equipment.
Five out of six participants had no serious adverse effects to the procedure but one participant did experience a reaction in his treated eye resulting in a notable decline in visual function.
In addition, the retinal tissue in all participants appeared to deteriorate in the treated eye at the same rate as the untreated eye during the course of the study.
Therefore, we concluded that the experiment itself did not improve visual function or halt the degradation of retinal tissue caused by choroideremia. We learned valuable information about safety and how to measure vision for future gene therapy trials.