Cost regulators for NHS funded therapies in England and Wales have now published final draft guidance approving GlaxoSmithKline’s gene therapy Strimvelis for an ultra-rare immune deficiency condition commonly referred to as bubble baby syndrome.

Severe combined immunodeficiency due to adenosine deaminase deficiency, or ADA-SCID, is an inherited genetic condition affecting the body’s white blood cells, that renders the body’s immune system unable to function properly, leaving patients at high risk of developing life-threatening, recurrent infections.

Around three babies a year in England are born with ADA-SCID. If left untreated, quality of life is affected by developmental delay, chronic diarrhoea, failure to thrive and recurrent infections, and infants die before school age.

Current treatment is a stem cell transplant, which can restore the immune system if successful but carries a risk of mortality and graft versus host disease, while closely matched stem cell donors are also hard to find.

Strimvelis is a gene therapy in which a patient’s bone marrow cells are removed and modified outside the body to produce working ADA enzyme, and then reintroduced via an infusion drip into a vein. The National Institute for Health ad Care Excellence is backing its use when no suitable matched related stem cell donor is available.

Costing 594,000 Euros, the treatment is usually given once only and the effects are thought to be life-long, NICE said. Also, as Strimvelis has to be administered at a hospital in Milan, people will travel to Italy to have the treatment, as part of their care provided by the NHS, it noted.

“Strimvelis represents an important development in the treatment of ADA-SCID, offering the potential to cure the immune aspects of the condition and avoid some of disadvantages of current treatments,” said Professor Carole Longson, director of the centre for health technology assessment at NICE.

“This means that children born with ADA-SCID will now have a better chance of being able to lead as near normal a life as possible, going to school, mixing with friends, free from the constant threat of getting a potentially life-threatening infection.”

The evaluation of Strimvelis is the first time that NICE has applied the higher cost effectiveness limits introduced last year for the assessment of treatments for these extremely rare conditions.

If there are no appeals to the recommendations, the Institute says it expects to publish final guidelines in February.