British scientists have successfully used gene therapy to restore some sight to a legally blind child with a genetic retinal disease. All 11 children in the clinical trial saw improvements in their vision within weeks of one surgical treatment.
The children were all born with a severe form of retinal dystrophy called LCA4, which leaves them with limited ability to perceive light. The disease is caused by mutations in the AIPL1 gene, resulting in defects in the protein of the same name. This protein plays a key role in converting light into electrical signals that the brain can interpret.
In the study, the children received gene therapy targeting AIPL1, which was delivered directly into their retinas. Four weeks after treatment, their vision was assessed using a series of tests including following a pen light, moving a crayon between cups, locating a white object on a dark background and navigating a hallway. Retinal structures and brain activity in response to light were also measured.
Sure enough, all 11 children treated so far have had a "meaningful response" to the treatment. They were all between one and four years old when they received treatment, and researchers followed their progress for three to four years.
The first four children received treatment in one eye, and the treated and untreated eyes were tested separately. By the end of the study period, none of the four children could feel or measure light in their untreated eyes. The treated eye progressed from legally blind to low vision.
A second group of seven children also received gene therapy, this time in both eyes. The team said their trial is still ongoing, but early results look equally encouraging.
"The improvements demonstrated are unparalleled in therapeutic efficacy compared to any ocular gene therapy for inherited retinal diseases," said Alexandria Forbes, Ph.D., president and CEO of MeiraGTx, the genetic medicine company developing the therapy. "These improvements not only have a meaningful impact on vision, but also bring life-changing benefits to all areas of development including communication, behaviour, education, mood, psychological benefits and social inclusion."
These studies continue, and the gene therapy has been designated an orphan drug by the U.S. FDA and the European Commission, and a rare pediatric disease (RPDD) by the FDA. Gene therapies for other forms of retinal dystrophies have also received FDA approval, raising hope for wider use.
Data from the first four children have been published in The Lancet. Some of the test results can be seen in the video below, with significant improvements between treated and untreated eyes.