Gene therapy for blindness heading for approval

The US Food and Drug Administration looks set to approve a gene therapy for the treatment of a rare form of blindness, following clinical trials and the recommendation of a panel of independent advisors.

The therapy, marketed as Luxturna by developers Spark Therapeutics, is used to treat an uncommon form of inherited childhood blindness called Leber congenital amaurosis.

The condition is caused by a mutation of a gene dubbed RPE65. Spark’s therapy involves injecting a fully functional copy of the gene, packed into an adenovirus (the family of viruses that cause a range of conditions such as common colds, sore throats and conjunctivitis) and injected behind the retina.

A clinical trial conducted in France – with results published in the journal Molecular Therapy in September this year – involved nine patients who were given the injections. All nine were followed for 12 months, and six were monitored for between two and three and a half years.

Lead author Guylene Le Meur of University Hospital Centre de Nantes and colleagues reported that all patients showed good tolerance of the treatment. The researchers also observed a trend towards improved visual focus, including the stabilisation of the visual field.

The strategy is not a gene-editing approach. The patient’s own mutated form of the RPE65 gene remains in place. The replacement is applied locally where it is copied into retinal cells.

Following the recommendation of the FDA’s advisory panel last week, Luxturna might become the first gene replacement therapy ever approved for commercial use.