(Reuters) – The U.S. Food and Drug Administration on Tuesday approved Spark Therapeutics Inc’s treatment for a rare form of blindness, marking the first time the agency has approved a gene therapy for an inherited disease.
The drug, Luxturna, treats inherited retinal disease caused by defects in a gene known as RPE65, which tells cells to produce an enzyme critical for normal vision. The condition affects between 1,000 and 2,000 people in the United States.
Luxturna works by delivering 150 billion viral vector particles containing a correct copy of the RP65 gene to retinal cells, restoring their ability to make the needed enzyme. It is designed to be given just once, though it is unclear how long the benefit will ultimately last.
Clinical trials of Luxturna showed that 93 percent of participants experienced some improvement in their functional vision as measured by their ability to navigate obstacles in poor light after one year.
Gene therapy in general aims to treat disease by manipulating genes at a cellular level. The field is gain gaining momentum following several high profile failures in the late 1990s and early 2000s. The FDA recently updated its guidance to industry to help speed the development of such therapies.
“The FDA appears to be accommodating and supportive of helping companies get through the regulatory process in an accelerated and streamlined manner,” Michael Yee, an analyst at Jefferies Equity Research, said in a recent research report on gene therapies.
But gene therapies, designed mainly for diseases with small patient populations, carry high prices. Analysts estimate Luxturna could cost as much as $1 million per patient.
The company said it would not announce the price of the drug until early January. It said Luxturna is expected to be available in some treatment centers late in the first quarter of 2018.
Inherited retinal diseases are a group of rare conditions caused by mutations in one or more than 220 different genes, including the RPE65 gene.
Luxturna was tested in patients with one such condition, Leber congenital aumaurosis, but can be used in any person with a condition mediated by the RPE65 mutation.
Spark’s shares jumped as much as 6.8 percent to $52.30 on the Nasdaq stock exchange before dropping back to $49.10. The approval had been expected.
Reporting by Toni Clarke in Washington; Editing by Chizu Nomiyama and Susan Thomas