Luxturna, a new form of gene therapy, has been approved by the U.S. Food and Drug Administration on Dec. 19 for the treatment of a hereditary disease that leads to blindness. It was first announced on Oct. 10, with a subsequent panel discussion to deliberate its approval.
The treatment developed by Philadelphia-based Spark Therapeutics is also the first ever gene therapy requiring direct administration to be approved by the agency. It specifically targets a retinal dystrophy called biallelic RPE65 that is caused by a gene mutation.
Rare RPE65 Mutation Affects Over A Thousand Americans
Up to 2,000 people in the U.S. are affected by such condition, which is commonly unidentifiable until symptoms manifest during adulthood. The FDA explains that the mutation particularly targets RPE65, a gene providing the instructions for production of an enzyme critical to the maintenance of 20:20 vision. This protein is involved in the conversion of light into signals that are interpreted by the brain as images.
With a reduced or absent activity of such gene, patients with confirmed RPE65 mutation experience visual impairment either in childhood or adolescence. Such symptom then progresses over time, resulting to complete loss of vision.
To improve a patient's vision, Luxturna therapy is delivered directly to cells in the patient's retina using two injections carrying normal copies of the RPE65. Such copies were made by modifying the DNA of a naturally occurring virus to imitate the structure of a normal RPE65. By introducing these copies, a patient's natural ability to manufacture the enzyme will gradually be restored.
The subretinal injections are to be done in each eye by an intraocular surgeon over separate sessions, with a minimum of six days between procedures. Patients will also be required to take prednisone over a short period to manage possible immune reactions to the gene therapy. Common reactions include redness of the eyes, tearing of the retina, an increase of intraocular pressure, or cataract.
According to reports, the therapy has been designed to be administered only once, and the length of its effects remains unclear.
Luxturna Therapy Paves Way For More Groundbreaking Treatment
FDA Commissioner Scott Gottlieb says the approval of Luxturna serves as a "turning point" for the agency. He also revealed that in 2018, guidelines for developing gene therapies will be established. Guiding rules in the document will be used in evaluating and reviewing treatment for diseases considered by the FDA as high-priority.
Other medical breakthroughs recently approved by the agency include Brineura, a treatment for Batten Disease by Biomarin, and a digital pill featuring sensor technology allowing physicians to determine whether it has been ingested or not.