First UK child receives gene therapy for inherited sight loss

An 11-year-old girl has become the first UK patient to receive an experimental gene therapy for an inherited eye disorder.

The child was diagnosed as a baby with Bardet Biedl Syndrome (BBS), a rare genetic condition that affects around one in 100,000 people in the UK. More than 20 genes have been associated with BBS, with mutations in the BBS10 gene accounting for more than 20 percent of cases. The gene therapy administered at St Helier Hospital in Sutton, part of Epsom and St Helier University Hospitals NHS Trust, was developed by MeiraGTx for patients with BBS10 mutations.

'We were told that possible gene therapy was many, many years away, and was likely to arrive after [she] had entirely lost her sight – so we were surprised and delighted when we learned this treatment had become available, and that [she] would be one of the first patients in the world to receive it', explained the child's father.

One of the main features of BBS is rod-cone dystrophy, a progressive retinal degeneration that causes night blindness, loss of peripheral vision and, ultimately, sight loss. BBS can also cause obesity, kidney abnormalities, developmental delay and extra fingers and/or toes, although symptoms and severity vary between individuals.

The gene therapy, named AAV8-RK-BBS10, delivers a functional copy of the BBS10 gene through a one-off injection beneath the retina. The child received the therapy in only one eye under a Medicines and Healthcare products Regulatory Agency Specials licence, which allows an unlicensed medicine to be supplied to meet the special clinical needs of an individual patient where there is no suitable licensed alternative.

'By giving a healthy copy of the gene, it helps save those cells, and the hope is to either stabilise or improve vision,' Mr Neruban Kumaran, consultant eye surgeon at Epsom and St Helier University Hospitals NHS Trust, said.

The team at St Helier Hospital worked with experts at Great Ormond Street and Moorfields Eye Hospital, London to identify eligible young children with BBS10 mutations. Before this procedure, only one other patient worldwide – a 17-year-old girl from Canada – had received the treatment, also at St Helier Hospital. Following treatment, patients attend regular follow-up appointments, where their vision is monitored using a range of sight tests, including reading letters from an eye chart and identifying different shades of colour.

Kumaran cautioned that it will take several years to determine whether the treatment is effective. He said: 'There's been some very positive feedback from a mixture of the patients and the families that suggest their vision may be better. Early reports from the families have been very promising, and it gives us lots of hope. But in practice, it will take many years before we're sure.'