Retinal gene therapy stops choroideremia development and improves vision
5 years after one-time retinal gene therapy, all 14 patients with choroideremia have experienced arrest of the disease and improvement in sight abilities.
Mutations characterise Choroideremia in the CHM gene. With a various age of onset, patients experience a gradual loss of vision beginning from the periphery of sight. As central vision is still functional, there is potential to intervene by therapy arresting the disorder.
A trial to stop vision loss was conducted on 14 patients in the UK. Adenovirus vector inserted normal CHM gene copies into retina cells. The procedure was performed only on one eye of each patient to distinguish between experimental and control group.
After 2 years, the vision has improved in all treated eyes (by +4,5 letters in chart sight test) and has declined in most of the untreated eyes (by -1,5 letters on average).
Following full 5 years after one-time gene therapy, the arrest of the disease was sustained. The primary goal of the trial, safety assessment, was met in almost all cases during the whole period. Only complications were on the very beginning, where in one case there were surgical complications and in one case there was an adverse reaction to the viral vector.
More: “Beneficial effects on vision in patients undergoing retinal gene therapy for choroideremia”, K. Xue et al., 2018, doi:10.1038/s41591-018-0185-5.