A team of researchers report findings from a Phase I/II gene therapy clinical trial for patients with Leber congenital amaurosis, which found that the gene therapy could significantly restore eyesight to patients. The team’s work and study results are described in The Lancet.
Leber congenital amaurosis is an eye condition that some people are born with. Specifically, this condition is caused by mutations, or changes to a specific gene in the body, GUCY2D. This gene is responsible for creating specific proteins that help support a person’s vision. Mutations in the gene can affect the retina, in particular, and lead to a worsening of vision as a person gets older. It can also cause other vision challenges, such as sensitivity to light. An estimated 100,000 people have this condition globally.
The clinical trial, a Phase I/II study, examined the safety and preliminary efficacy of the gene therapy. Fifteen patients were enrolled, include three pediatric patients. Each patient had severe vision challenges defined as 20/80 eyesight, meaning that someone without vision impairment could see an object clearly from 80 feet away that someone with leber congenital amaurosis would need to be 20 feet away to see. Glasses did not work for these patients either because they do not correct underlying medical challenges.
During the trial, patients could have received different doses of ATSN-101, a gene therapy using an AAV5 vector that is injected under the retina. During phase I, groups of three adults received one of three doses, and then during phase II, the higher dose was tested on groups of adult and pediatric patients.
Results were observed quickly after injection, relatively speaking. Many patients experienced a change to their vision within a month of the injection, and the benefits lasted for roughly a year. Patients were evaluated using a range of eye exams and participated in mobility tests; patients receiving the higher dose passed with flying colors.
The most significant finding: two patients who received the higher dose experienced a nearly 10,000-fold improvement in their vision.
Sources: Science Daily; Lancet