Strimvelis is the first ex-vivo stem cell gene therapy to treat patients with a very rare disease called ADA-SCID (Severe Combined Immunodeficiency due to Adenosine Deaminase Deficiency), a rare disorder caused by the absence of an essential protein called adenosine deaminase (ADA ), which is required for the production of lymphocytes . Children born with ADA-SCID do not develop a healthy immune system so we can not fight off everyday infections, which results in severe and life-threatening illness. In the child’s first year of life. ADA-SCID is estimated to occur in approximately 15 patients per year in Europe.
The treatment was developed at San Raffaele Telethon Institute for Gene Therapy (SR-Tiget) and developed by GlaxoSmithKline (GSK) through a 2010 collaboration with Fondazione Telethon and Ospedale San Raffaele (OSR) . GSK, working with the biotechnology company MolMed SpA, developed a manufacturing process that was previously only suitable for clinical trials .
In April 2016, a committee at the European Medicines Agency recommended marketing approval for adenosine deaminase deficiency , for whom no matched HSC donor is available, on the basis of a clinical trial that produced a 100% survival rate; The median follow-up time was 7 years after the treatment was administered.  75% of people who receive the treatment no further enzyme replacement therapy .  Efforts had begun 14 years before. The total number of children treated was 22  and 18.  Around 80% of patients have no matched donor.  Strimvelis was approved by the European Commission on 27 May 2016.
As of 2016, the only site approved for manufacturing MolMed. 
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The condition affects about 14 people in Europe and 12 in the US 
The price for the treatment was set at € 594k, 2 times the annual cost of enzyme replacement therapy injections.  enzyme replacement therapy for ADA requires weekly injections and costs about $ 4.25 million for one patient over 10 years. 
The treatment is personalized for each patient; hematopoietic stem cell (HSCs) are extracted from the patient and purified so that only CD34 -expressing cells remain. These cells are cultured with cytokines and growth factors and then transduced with a gammaretrovirus containing the human adenosine deaminase gene and then reinfused into the patient. These cells take on the role of the bone marrow , replicating and creating cells that adenosine deaminase protein, resolving the problem.   As of April 2016, the transduced cells had a shelf life of about six hours. 
Prior to extraction, the patient is treated with granulocyte colony-stimulating factor in order to increase the number of stem cells and improve the harvest; After That goal prior to reinfusion, the patient is Treated with busulfan or melphalan to kill you Many of the person’s Existing HSCs pour augmenter the chances of the new cells’ survival.  
The most common side effects in clinical trials have been pyrexia , increased liver enzyme levels, anemia , neutropenia , hemolytic anemia , aplastic anemia and thrombocytopenia . 
- ^ Jump up to:a b c EMA Strimvelis Page accessed April 13, 2016
- Jump up^ Booth C et al. Treating Immunodeficiency through HSC Gene Therapy. Trends Mol Med. 2016 Apr; 22 (4): 317-27. PMID 26993219
- Jump up^ Denise Roland for the Wall Street Journal. April 1, 2016Glaxo’s Potential Cure for “Bubble Boy Disease” One Step Closer
- Jump up^ Andrew Ward for the Financial Times. April 1, 2016GSK to allow staggered payments for EMA-approved gene therapy
- ^ Jump up to:a b Ketaki Gokhale for Bloomberg News. April 1, 2016 Glaxo’s Bubble Boy Gene Therapy Wins EU Drug Agency Nod
- Jump up^ “StrimvelisTM receives ADA-SCID – GSK” .
- ^ Jump up to:a b Ben Adams for FierceBiotech Apr 4, 2016 Strimvelis to be the start of a whole new gene therapy platform for GSK and partners
- Jump up^ Regalado, Antonio (May 6, 2016). “Gene Therapy’s First Out-and-Out Cure Is Here” . MIT Technology Review . Retrieved 2016-05-12 .
- Jump up^ “Does the price of Strimvelis create a new ‘glass ceiling’? – groupH – Inspiration” . www.grouph.com . Retrieved 2017-02-26 .
- ^ Jump up to:a b Candotti F. Gene transfer into hematopoietic stem cells as treatment for primary immunodeficiency diseases. Int J Hematol. 2014 Apr; 99 (4): 383-92. Review. PMID 24488786
- ^ Jump up to:a b Touzot F, et al Gene therapy for inherited immunodeficiency. Expert Opin Biol Ther. 2014 Jun; 14 (6): 789-98. doi: 10.1517 / 14712598.2014.895811. Epub 2014 Mar 8. Review. PMID 24823313