Spark Therapeutics treatment on course to become the first gene therapy for inherited retinal blindness

Spark Therapeutics treatment for a rare form of inherited blindness looks on course to become the first gene therapy to be approved in the USA

Today saw a big announcement of the initial results from a pivotal late stage clinical trial for a form of inherited retinal degeneration. This announcement is the culmination of many years of trailblazing research emanating from the University of Pennsylvania in the area of gene therapy for rare forms of inherited blindness.

Spark Therapeutics have developed a gene therapy for a rare form of blindness known as Leber congenital amaurosis (LCA). Specifically, their therapy is for a particular form of LCA known as LCA2, as it is caused by mutations in the RPE65 gene. Individuals with this condition experience night blindness as one of the earliest symptoms and their vision loss often deteriorates to blindness. There is currently no approved therapy. Spark’s therapy, known as SPK-RPE65, replaces the defective gene by using harmless viruses to deliver a working copy of the RPE65 gene directly to the patient’s eye.

In a study of 31 people with LCA2, 21 received the therapy, and 10 people were in the control group. After treatment, two thirds of individuals in the therapy group were able to successfully navigate a specially designed mobility course under very low light conditions indicating a restoration in their vision. There were no serious events during the trial related to the therapy and it is safe and well tolerated. The trial also showed that participants who received the treatment also outperformed those in the control group on two secondary goals: improving light sensitivity of the eye and change in mobility test score for the first eye treated. The third endpoint, which is the ability to read further on the standard eye chart didn’t result in a statistically significant result.

Only individuals with this specific form of LCA will benefit from this therapy as it is replaces the defective RPE65 gene, responsible for subtype 2 of the disease. This highlights the importance of Irish patients being clinical trial and novel therapy ready. Receiving a confirmed genetic diagnosis and being part of our national register known as Target 5000 will place Irish patients at the forefront of this new era of clinical trials and therapies for rare inherited diseases of the retina.

Also with respect to Ireland, the Trinity College Dublin spin out company, Genable technologies founded by a world renowned team in ocular genetics is another pioneering company working in this area. Genable is backed by Irish venture capital and international patient organisations including Fighting Blindness.  Spark are the manufacturing partner for Genable’s gene therapy RhoNova for dominant retinitis pigmentosa caused by mutations in the rhodopsin gene that is currently in development.

Spark will now look to engage with the US drug regulators, the FDA, in order to file for approval of the therapy next year. We will be following these developments closely over the next few months and aim to keep you fully informed. From our point of view, this is a momentous step forward on the road to treatments for all forms of retinal degeneration.