Voretigene neparvovec, which will be sold as Luxturna, is made by Philadelphia-based Spark Therapeutics Inc.
The one-time treatment is approved for children and adults with retinal dystrophy due to a mutation of the RPE65 gene, which causes severe visual impairment beginning in infancy. As it progresses, patients experience gradual loss of peripheral and central vision, which can eventually lead to blindness.
There are more than 200 genes that can cause retinal dystrophy. Patients can be tested to determine whether the cause is indeed a mutation of the RPE65 gene and they are thus a potential candidate for this new treatment.
Luxturna is only the third gene therapy approved for use in the United States, preceded by two others this year. However, this is the first to correct an inherited genetic mutation. Some scientists believe that the approval could open the door to other treatments that correct flaws in the inherited genome.
FDA Commissioner Dr. Scott Gottlieb called Tuesday's approval a milestone for gene therapy and noted the potential for treatment of many diseases.
the approval "marks another first in the field of gene therapy -- both in how the therapy works and in expanding the use of gene therapy beyond the treatment of cancer to the treatment of vision loss."
Adding a third gene
Luxturna supplies a normal RPE65 gene to retinal cells. It is a liquid that is injected into the eye with a microscopic needle during a surgical procedure. Within the liquid is a gene therapy virus that contains a healthy version of the gene.
Essentially, the drug adds a third version of the gene, which, unlike the mutated genes, is able to code for a protein crucial to vision.
Risks of the treatment include cataracts, elevated eye pressure, retinal tears and holes, and inflammation.
Researchers treated 41 patients between 2007 and 2015 to establish safety and efficacy. Those patients are still being followed. In a separate trial, researchers treated 31 patients and measured changes in their vision based on their ability to complete an obstacle course in low-level light.
The treatment is not permanent, according to William Hauswirth, an ophthalmology professor at the University of Florida College of Medicine who worked on developing it. He noted one study
found most patients' vision regresses to what it was before therapy after about six years later, but he still considers it successful. It may be possible for patients to be treated again but that research is still underway, he said.
'This is incredible!'
Perhaps the most well-known patient from clinical trials of Luxturna is singer Christian Guardino, who appeared this year on season 12 of "America's Got Talent." The 17-year-old from Patchogue, New York, was eliminated from the show in the semifinals but told his mother, Elizabeth, that the ability to walk unaided onto the stage and see faces in the audience gave him confidence.
In October, he told an FDA advisory committee
that the first 12 years of his life were spent in darkness, but he is now able to see things he hadn't seen before, thanks to the treatment.
On Facebook, he called the new approval "the best Christmas gift ever" and said, "this is just incredible!"
When the drug becomes available in early spring, it will become the first approved treatment option for the condition. An estimated 1,000 to 2,000 people in the United States stand to benefit from this option, according to Spark.
The company said cost information and details on timing will be released next month.