03 Nov Gene Therapy Prevents Blindness
An FDA panel has unanimously recommended approval of Luxturna, a new gene therapy for the treatment of two inherited retinal diseases which cause blindess.
The FDA will formally meet in January 2018 to officially decide if Luxturna (voretigene neparvovec) will be approved. This may be the first gene therapy treatment used for eye disease.
Luxturna is manufactured by Spark Therapeutics and is intended to be used to treat patients with Leber’s Congenital Amaurosis (LCA) and retinitis pigmentosa 20.
Mutant Genes Produce Mutant Proteins
Both Leber’s Congenital Amaurosis (LCA) and retinitis pigmentosa 20 develop from a defective gene known as RPE65.
Genes produce proteins.
The defective gene can not produce a functioning protein necessary for the normal “vision cycle” to occur.
The “vision cycle” is the process whereby light is translated by the retina into electrical signals which are understood by the brain.
Both Leber’s Congenital Amaurosis and retinitis pigmentosa 20 can lead to blindness due to non-functioning vision cycles. There is presently no cure or treatment for either disease.
Eye Injection
Luxturna, a one time treatment, will insert “normal” DNA into the retinal cells. Luxturna will be injected into the eye to allow direct exposure to the retina.
The normal DNA will contain intact and functioning copies of RPE65 which will produce a normal protein.
Production of the normal protein should restore, or improve, the retina’s “vision cycle” and lead to improved vision.
FDA Fast Track
Spark Therapeutics has been able to achieve “Fast Track” status for Luxturna. FDA reviews “fast track” applications as they have the potential to significantly impact the treatment of a disease.
In these cases, there is no present treatment.
Results submitted to the FDA include the mobility results of patients with the confirmed inherited retinal diseases. The patients were subjected to a maze under varying lighting conditions. The maze would change to prevent memorization.
In most situations, patients vision improved such that successful navigation through the mazes was achieved with only the equivalent of a nightlight. Most patients have exhibited improvement lasting over a year. The study includes patients maintaining improvement for 2-4 years.
Inherited retinal diseases are caused by over 220 known defective genes. Retinitis pigmentosa 20 and LCA are two diseases caused by the same gene.
I should also point out that “retinitis pigmentosa” is a collection of diseases caused by variuos genes. Luxturna will treat only retinitis pigmentosa 20.
All the best,
Randy
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