Second gene therapy wins approval in Europe

The European Commission has granted marketing authorisation for a gene therapy to treat children with an extremely rare, life-threatening genetic disorder. It is only the second time a gene therapy has been approved in Europe.

The treatment – called Strimvelis – was developed by GlaxoSmithKline (GSK) and Italian scientists for children affected by ADA Severe Combined Immune Deficiency (ADA-SCID), which leaves children extremely susceptible to everyday infections. Without treatment, children with the condition rarely live past their first birthday and in some cases must live in plastic, germ-free chambers, giving rise to the name the condition is more commonly known by – 'bubble baby' disease.

'Today's approval is the result of many years' work with our collaborators in Milan and is the next step towards bringing life-changing treatment to patients with ADA-SCID and their families. This is the start of a new chapter in the treatment of rare genetic diseases and we hope that this therapeutic approach could also be used to help patients with other rare diseases in the future,' said Martin Andrews, head of the rare disease unit at GSK.

ADA-SCID is thought to affect around 350 children worldwide. The condition is caused by a single genetic defect which stops the production of an essential protein – adenosine deaminase (ADA) – required for the development of a normal immune system.

Strimvelis works by taking the patient's own stem cells from bone marrow and inserting a working copy of the defective gene into the cells. The gene-corrected cells are then re-introduced to the patient. As the treatment does not rely on a third-party donor, there is no risk of the body rejecting the inserted cells as there would be in standard bone-marrow transplant treatment. However, the patients need to be pre-treated with low-dose chemotherapy in order to improve the process of reintroducing the modified cells into the patient's bone marrow.

Clinical studies to date have demonstrated that the procedure significantly improves survival of children with ADA-SCID. All of the 12 children who received Strimvelis in the main clinical trial that formed the basis of the regulatory decision are still alive today, with an average follow-up up of seven years.

The approval of Strimvelis, which was recommended for marketing approval in the European Union by the European Medicines Agency (EMA) in April earlier this year (see BioNews 846), could spur the development of gene therapy for more widespread illnesses caused by faulty genes, such as muscular dystrophy, cystic fibrosis and many types of blindness.

Glybera, a gene therapy for a pancreatic disorder, was the first gene therapy to gain approval by European regulators back in 2012 (see BioNews 680). It also made history as the first drug with a price tag of US$1 million. Although GSK has not yet revealed the cost of Strimvelis, Reuters has previously reported that it will be 'very significantly less than $1 million', according to a source close to the company.

'We are absolutely committed to getting the price right,' said Patrick Vallance, president of research and development at GSK. 'It's obvious that you can't charge a price that is unaffordable.'

Following market approval, decisions about price take place at the level of each EU Member State.