3.1
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'.