Spark Therapeutics Inc’s experimental gene therapy for a rare inherited form of blindness improves vision, though it is unclear whether the benefit lasts over time, according to a preliminary review by the U.S. Food and Drug Administration.

The therapy, Luxturna, or voretigene neparvovec, would be the first-ever gene therapy for any inherited disease to be approved in the United States.

The FDA noted there is no available long-term data to show whether the effectiveness of the therapy is maintained after a year, so the clinical benefit beyond that “is unclear.”

Clinical trial results showed 93 percent of participants experienced some improvement in their functional vision as measured by their ability to navigate obstacles in poor light.

If approved, analysts expect Luxturna to generate annual sales of more than $400 million by 2021.

Source: The New York Times