3 The technology


Strimvelis (GlaxoSmithKline) is an ex vivo gene therapy treatment. A patient's bone marrow-derived cells (CD34+ cells) are collected and modified so that they produce functional adenosine deaminase (ADA) enzyme. The modified cells are infused back into the patient, where they engraft in the bone marrow and repopulate the haematopoietic system with cells that produce active levels of the ADA enzyme. Treatment with Strimvelis is suitable if enough CD34+ cells can be harvested, and a bone marrow biopsy can show whether this is feasible. Strimvelis treatment is a single-dose treatment, and the effects are thought to be lifelong. It has a marketing authorisation in the UK for people with 'severe combined immunodeficiency due to adenosine deaminase deficiency (ADA–SCID), for whom no suitable human leukocyte antigen (HLA)‑matched related stem cell donor is available'.


The only approved manufacturing centre for Strimvelis is in Milan, Italy. Because of the 6‑hour shelf life of Strimvelis, the treatment is currently only available at Hospital San Raffaele Telethon Institute for Gene Therapy in Milan. People from England would need to travel to this hospital for treatment with Strimvelis. Arrangements for NHS funding for travel and accommodation costs for people having Strimvelis and their families will be confirmed by NHS England.


The adverse reactions listed in the summary of product characteristics for Strimvelis include: anaemia, asthma, autoimmunity, atopic dermatitis, eczema, hypertension, hypothyroidism, neutropenia, pyrexia and allergic rhinitis. For full details of adverse reactions and contraindications, see the summary of product characteristics.


The price for Strimvelis is €594,000 (excluding VAT; company's evidence submission; at an exchange rate of €1 to £0.85, this equates to £505,000).