FDA advisory committee vote 16-0 for first even gene therapy for rare blindness

By Dr. Ananya Mandal, MDOct 16 2017

A panel of advisors to the United States Food and Drug Administration (FDA) has voted unanimously in favor of an experimental gene therapy to treat patients with a rare kind of hereditary blindness.

The Cellular, Tissue and Gene Therapies Advisory Committee voted 16-0 to recommend this new therapy. The FDA usually accepts the recommendations from its advisory committee. If so, this could be the first one time gene therapy approved for an inherited disease condition, creating history.

Philadelphia based Spark Therapeutics developed this new therapy called Luxturna> (voretigene neparvovec) that involves injection of a healthy version of the RPE65 gene into the eyes of patients who have a mutated form of this gene. This gene makes a special protein in the eye that is necessary for vision. Although perfect vision may not be achieved, the treatment does provide substantial improvements in vision to these blind patients. Luxturna is considered to be true gene therapy wherein a good, functioning gene is injected to perform the work of a defective gene. Until now Spark has not announced the pricing for their product but it could be high. Experts predict a price of $750,000 to $1 million for both eyes. The FDA would not consider this recommendation and has set a deadline of mid-January 2018, to decide upon the Spark treatment’s fate.

The therapy could benefit around 1000 to 2000 people in the United States who have inherited retinal disorders that result from a defective RPE65 gene. The problem is usually detected in childhood as Leber congenital amaurosis or retinitis pigmentosa. Vision is low and there are symptoms of night blindness (inability to see in low light conditions) and defective peripheral vision or central vision. With time the children become completely blind usually by the age of 16. According to Jean Bennett, an ophthalmologist at the University of Pennsylvania, who was one of the researchers involved in the development of Luxturna, the children with low vision due to the genetic defect, after injection of the therapy could become much more independent.

The committee met all day on Thursday and voted after it heard accounts from patients who had benefited from the treatment. 29 patients aged ranging from 4 to 44 were presented before the committee to show the benefits from this treatment. None of the patients had gained full vision but 90 percent of them showed significant improvement especially in low light vision. The therapy was found to relatively safe. Some cases of raised intra-eye pressure was seen.

Katherine High, president and head of research and development at Spark said that there was a hope of developing medicines from the Human Genome Project. It was a complex deal but success in this field could mean a lot for patients with rare inherited genetic disorders. There are several other genetically inherited conditions such as Huntington’s disease (an inherited disorder of the muscles and nerves) and hemophilia (blood coagulation disorder) for which researchers are working towards gene therapies.