An FDA (Food and Drug Administration) review approved a new drug that helps cure an inheritable form of blindness through gene therapy. The therapy has shown that of 21 patients, 11 show much improved vision, while 93 percent have some improvement in vision. The gene therapy, Voretigene neparrovec, helps in patients who have a biallelic RPE65 mutation associated retinal dystrophy. Despite results the FDA are still deciding whether to approve the therapy. There is still unknown information for how the medication works in the long-term.
A group of rare blinding conditions caused by mutations in any one of more than 220 different genes is called inherited retinal dystrophies. Retinitis pigmentosa, a disorder characterized by a reduced ability to perceive light and progressive loss of visual field, most common. Leber congenital amaurosis, a retinitis pigmentosa subtype, is characterized by early onset and nystagmus (is a vision condition in which the eyes make repetitive, uncontrolled movements). Biallelic mutations in this gene, can be described as Leber congenital amaurosis type 2, retinitis pigmentosa type 20, early-onset retinal dystrophy, and other clinical labels for severe rod-mediated inherited retinal dystrophies, leading to complete blindness. Proof of this gene therapy for RPE65 was through canine and murine animal models using a biogenetic adenoassociated virus (AAV), showing that the gene could be corrected. After additional testing and studies in large animals, human clinical trials have supported the gene therapy.
This article is relevant to me as I would like to continue in the health care field. As a health care provider, like doctors, they look for innovative ways to help their patients. If there is a breakthrough in a medication they can use it to help the patients. Some doctors can also recommend patients to clinical trials such as ophthalmology (exact medication for Leber) in this case. Though this information is fascinating in having trials to cure rare disorders, personally I would still like to keep my health field which is becoming a surgeon. The research into this article really was an eyeopener to a different profession in the health care field.
The RPE65 mutation consisted to three trials called phases. Phase 1&2 studies show the benefits of gene replacement in RPE65. Phase 3 studies assessed the efficacy and safety of Voretigene neparvovec in participants whose inherited retinal dystrophy would otherwise progress to complete blindness. Phase 3 was done in two separate locations in the USA, it consisted of 3 years or older patients with, a visual acuity of 20/60 or worse or with a confirmed genetic disorder of biallelic RPE65 mutations. The endpoint was 1-year change in MLMT (multi-luminance mobility testing) performance, measuring functional vision at specific light levels.
Phase 1 trials, done at the Children’s Hospital of Philadelphia, showed safe and stable improvements in retinal and visual function in all 12 participants. Most of the participants showed improved light sensitivity, navigational abilities, or visual acuity. There was a follow p study in which 11 of the 12 participants received an injection of the contralateral eye, which gained visual and retinal function in the second eye. The improvement has been around for 3 years, with observation that is still ongoing. Other RPE65 gene therapy trials, which were administered to only one eye per individual using different gene construct, vector formulations, or surgical approaches, have shown improvements in function of the retina but variable durability of effect.
In conclusion, there is an ongoing clinical trial all participants have the RPE65 mutation gene. Trials have been done to help replenish or replace the gene with phases that have been successful. The drug therapy is called Luxturna funded and made by Spark Therapeutics. Although there is no evidence on how the medication works on the long term, the drug has been approved and now the therapy is being decided on.