On Friday, November 23, the European Commission approved the first gene therapy for a sight loss condition. LUXTURNA (voretigene neparvovec-rzyl) was approved for the treatment of children and adults with vision loss caused by mutations in both copies of the RPE65 gene and who have sufficient viable retinal cells. Conditions caused by this type of mutation include very rare forms of Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP).
This is a landmark decision for people affected by sight loss caused by this specific genetic mutation, but it also marks a significant milestone for people living with other forms of inherited retinal degenerations or any other rare disease. This is an orphan drug, the first therapy of its kind to be approved in both Europe and the US, and it paves the way for other similar therapies coming down the track as it sets out a clear pathway to regulatory approval.
This approval is just the first stage in the process of making the treatment available to people living with vision loss due to this specific gene mutation. The next stage requires applications to be made by the pharmaceutical company, Novartis, for approval and reimbursement at a national level in each member state of the European Union (EU) or European Economic Area (EEA). It is anticipated that the first patients in Europe will receive the therapy by the end of 2019 or beginning of 2020.
Although this gene therapy will only benefit a small number of people living with a specific inherited retinal degeneration (IRD), this approval should give renewed hope to people living with all forms of genetic blindness. This is the culmination of many years of research and dedicated work by countless people in the vision community. There is promising research taking place in many other conditions and the approval of LUXTURNA paves the way for other therapies coming down the line. This is incredibly positive news for all of us.
What is a biallelic RPE65 mutation?
The RPE65 gene provides instructions for making an enzyme that is essential for normal vision. Mutations in the RPE65 gene lead to reduced or absent levels of RPE65 activity, blocking the visual cycle and resulting in impaired vision.
Every person has two copies of each gene, one inherited from each parent. The term biallelic means that the individual carries a mutation in both copies of the RPE65 gene (a paternal and a maternal mutation). These individuals experience progressive deterioration of vision over time. This loss of vision, often during childhood or adolescence, ultimately progresses to complete blindness.
Luxturna is a one-time gene therapy which works by delivering a normal functional copy of the RPE65 gene directly into the cells of the retina through a single retinal injection. This restores the production pathway for the required enzyme, improving the individual’s ability to detect light. The retinal cells then produce the normal protein that converts light to an electrical signal in the retina, thereby stopping further vision loss and restoring some functional vision. Luxturna uses a naturally occurring virus called an adeno-associated virus (which has been modified and rendered harmless) as a vehicle to deliver the normal human RPE65 gene to the retinal cells to restore vision.
For people to benefit from the therapy, they must have enough remaining viable retinal cells in the retina (the thin layer of tissue in the back of the eyes) as determined by a healthcare professional.
In the main clinical trial supporting the approval of Luxturna, patients treated with the medicine showed a significant improvement of night vision after one year. The most common side effects were conjunctival hyperaemia (eye redness), cataracts and increased intraocular pressure.