Gene Therapy Aimed At Restoring Sight For 30,000 People

British scientists are to launch the world’s first clinical trials of a controversial gene therapy to cure childhood blindness.

Researchers will test the treatment on volunteers with a rare inherited form of blindness, in which a single defective gene causes the retina to degenerate and eventually stop working as the child grows up.

The condition, called Leber’s congenital amaurosis, affects one in 80,000 in Britain. Children born with the defective gene are often completely blind by their 20s. If the trials are a success, it could revolutionise the treatment of more than 100 inherited forms of blindness that affect up to 30,000 people in Britain.

Patients taking part in the trial will be injected with a virus modified to carry a correct version of the faulty gene.

Once inside the eye, the virus ferries the healthy gene into the cells that make up the retina, halting and even reversing the damage caused.

The phase 1 trials are designed to assess the safety and efficacy of the treatment in 12 patients and will be carried out by the Institute of Ophthalmology at University College London and nearby Moorfields Eye Hospital. The safety of the treatment will be under particular scrutiny, following a gene therapy trial four years ago in which two children being treated for a rare immune disorder called Scid (severe combined immunodeficiency) developed leukaemia. Their cancers arose when a virus used to deliver healthy genes accidentally led to tumour-promoting genes.

Trials of the latest gene therapy in dogs have proved the treatment can improve and preserve vision enough for nearly blind animals to negotiate mazes.

“If this trial is successful it paves the way for the application of this technology in the treatment of many forms of inherited retinal degeneration and perhaps some of the more common disorders of the eye too,” said Robin Ali, an ophthalmologist at UCL, who is leading the team.

The researchers will know whether the treatment has worked in a few months.

“It will be many months before we have the full picture. We anticipate the best outcome in younger patients, as we will be treating the disease in the early stages of its development,” said Tony Moore, a leading retinal specialist on the team.

Alastair Kent, director of the Genetic Interest Group, a national alliance of more than 120 charities that support children, families and individuals affected by genetic disorders, said: “To hear of such quick progress in a gene therapy treatment is fantastic. We hope this success will lead to more funding of gene therapy research into rare conditions that currently have no cure or treatment.”

Andrew George, an immunologist at Imperial College London, said: “There is hope that once gene therapy is developed in the eye, scientists could move on to more complex organs.”