Macular degeneration, also called age-related macular degeneration (AMD), is a relatively common eye disease that progressively worsens over time. In 2010, 2.07 million Americans had AMD, and that number is expected to rise to 5.44 million by 2050. The condition is usually diagnosed in people older than 50 years and can lead to vision loss in severe cases.
Standard treatments for age-related macular degeneration include eye injections and photodynamic therapy. Unfortunately, these treatments are only available for wet AMD, a less common form of macular degeneration. Dry AMD, the most common form of macular degeneration, has no treatment.
However, in recent years, gene therapy has been studied as a potential option to treat both dry and wet AMD.
Gene therapy for wet AMD
In late 2019, scientists found a type of gene therapy that showed promise in treating wet AMD. In a clinical trial, patients who received the treatment (in the form of an injection) required no further injections in the following six months. Standard eye injections for wet AMD usually need to be done every month. As eye injections can be painful, this new therapy could potentially reduce wet AMD treatment to an annoyance that’s done once or twice a year rather than a gruelling monthly routine.
Dr. Szilárd Kiss, lead researcher of the trial, said some sort of gene therapy for wet AMD could be available “within the next three to five years.”
Gene therapy for dry AMD
Up until now, all the existing treatments for macular degeneration were for the wet form. But a 2020 study explored the effects of gene therapy in mice with both forms of AMD.
Researchers looking at mice with AMD found that they were all missing a certain enzyme called “Dicer.” Using an existing form of gene therapy used to treat other eye diseases, the team of scientists were able to restore the missing enzyme in the mice, and they think it could be done in humans as well. Furthermore, the researchers discovered that the missing Dicer enzyme was a factor in the development of both wet and dry AMD, so if the treatment were to be used in human patients, it could treat both forms.
“It [the discovery] certainly solidifies the idea that wet and dry AMD share a lot of mechanisms,” said Brad Gelfand, PhD, assistant professor at the UVA School of Medicine and lead researcher of the study. “This adds another important piece of evidence that the underlying mechanisms of these two processes are really tightly linked.”
Gelfand said this approach isn’t ready to be used in humans just yet, but when the time comes to use it in clinical trials and it’s found to be safe and effective, the treatment could be the first of its kind.
Gene therapy could truly be the nail in the coffin for age-related macular degeneration.
Written by Natan Rosenfeld