Rare form of blindness could be treated by breakthrough gene therapy

The world’s first breakthrough gene therapy trial for choroideremia, a genetic cause of blindness, has had successful results.

As reported in the Nature Medicine, the positive results of the world’s first breakthrough gene therapy trial enabled patients to gain a significant increase in their vision, therefore being a successful trial in reducing the rare form of blindness, choroideremia.

Details of the trial and the breakthrough gene therapy

Beginning in 2011 at the Oxford Eye Hospital as a part of the Oxford University Hospitals NHS Foundation Trust, UK, the trial involved 14 patients receiving a single injection into the back of the eye of a virus containing the missing gene.

By the end of the research period, there was a significant gain in vision across the group of patients.

The ophthalmologist who led the trial, professor Robert MacLaren said: “The early results of vision improvement we saw have been sustained for as long as we have been following up these patients and in several the gene therapy injection was over 5 years ago.”

“The trial has made a big difference to their lives.”

The success of this study has allowed a much larger international gene therapy trial to be conducted. Now being led by Nightstar Therapeutics, which is gene therapy spin-out company established by the University of Oxford and Syncona to develop the treatment further.

If proven to be successful, the follow-on trial could result in the gene therapy treatment being formally approved by the relevant regulatory bodies worldwide.

The concept of gene therapy and treating blindness

The concept of gene therapy is to modify or correct inherited diseases at the level of the DNA and if the therapy is successful, a single treatment might have life-long effects.

These early results support the notion that a single gene correction can have long-lasting beneficial effects on nerve cells of the retina to prevent blindness.

Choroideremia, is a rare form of inherited blindness, sometimes referred to as ‘retinitis pigmentosa’. The disorder causes progressive vision loss, ultimately leading to complete blindness. Typical symptoms usually begin with generally night-blindness, followed by vision loss in the mid-periphery. These “blind spots” appear in an irregular ring, only leaving patches of peripheral vision, while central vision is still maintained.

This chronic disorder has now become the most common cause of untreatable blindness in young people. However, with the breakthrough gene therapy, those suffering may have soon experience a salvation.