Voretigene neparvovec-rzyl ( Luxturna , Spark Therapeutics) is targeted for adults and children with confirmed biallelic  RPE65  mutation-associated retinal dystrophy. The treatment, which is delivered surgically via subretinal injection , is the first gene therapy approved in the United States that targets a disease caused by mutations in a specific gene.

The  RPE65  gene normally provides instructions for making an enzyme that is essential for normal vision. When there are mutations, that process is blocked, resulting in impaired vision. Luxturna  works by sending a normal copy of the  RPE65  gene directly to retinal cells, which then produces the normal protein to restore vision. The most common adverse reactions are conjunctival hyperemia, cataract, increased intraocular pressure, and retinal tear, according to the FDA press release.

"Fundamental" Advance

Dr. Gottlieb told reporters, "We are at the inflection point in medicine and health, witnessing the advent of new technology that has the potential to improve health and cure disease in fundamentally novel ways." Keeping up with the advances also provides challenges to the usual method of product regulation, he said, to get new products to consumers with the same gold-standard expectations for efficacy and safety.

Two other gene therapies approved this year are known as chimeric antigen receptor (CAR) T-cell therapies and involve reprogramming a patient's own cells to enable them to recognize and destroy cancer cells. Peter Marks, MD, PhD, director of FDA's Center for Biologics Evaluation and Research, told reporters that Luxturna adds a different discovery.

This one represents a more traditional form of gene therapy. Viruses are modified so they do not cause disease and are used to carry therapeutic genes to human cells, in this case retinal cells. "In contrast to the previous approvals, which we are calling," said Dr. Marks said. He said the FDA is looking to maximize its accelerated programs to move revolutionary products ahead.

In this case, the FDA worked with the manufacturer to arrive at an innovative clinical endpoint with Luxturna  that would demonstrate a meaningful effect for patients . The pivotal evidence for Luxturna  was based on a phase 3 study with 31 participants, and it measured change in 1 year in a participant's ability to navigate an obstacle course at various levels. Those in the Luxturna  group showed significant improvements compared with the control group.

Many More in the Pipeline

"There are more than 600 active new drug applications related to gene therapy products," he said. Though I can not confirm the numbers, he said, "researchers at the Massachusetts Institute of Technology estimate that about 40 gene therapies might win approval by 2022 from a current pipeline of 932 development candidates."