Severe combined immunodeficiency (SCID) is the name given to several rare inherited diseases where children are born with defective immune systems. It is also known as the ‘bubble boy disease’ because affected children are extremely vulnerable to infectious diseases, and some of them have become famous for living in a sterile environment.
In the most severe forms, children are unable to fight off even very mild infections and, without treatment, will usually die within the first year of life.
About the project
Professor Bobby Gaspar at Great Ormond Street Hospital and the UCL Institute of Child Health has pioneered potential treatments including gene therapy for SCID, and has been supported by the Medical Research Council (MRC) since 2006.
Several years of research focusing on a type of SCID known as adenosine deaminase deficiency (ADA), characterised by the lack of an enzyme called adenosine deaminase, led to the development of a treatment called OTL-101.
Since discovering the genes responsible for SCID, researchers have been working on new and improved forms of treatment. One exciting approach is gene therapy, where the defective gene can be replaced with a functional version, eliminating the cause of the disease.
Using the patient’s own stem cells provides a perfect match and eliminates the need for a donor search, along with the associated risk of complications such as transplant rejection. The stem cells are taken from the patient through a bone marrow extract and then genetically corrected outside of the body by replacing the missing or faulty gene. These corrected cells are then transplanted back into the body through intravenous infusion.
Impacts of the project
In 2015, Professor Gaspar’s work on gene therapy led to the launch of Orchard Therapeutics, a spin-out company which aims to further develop gene therapy to benefit patients with serious and life-threatening diseases. The company developed the innovative OTL-101 treatment.
In 2017, both US and UK drug regulatory authorities granted OTL-101 designations reserved for treatments addressing high unmet need. These developments show the commercial potential of Professor Gaspar’s work and highlight regenerative medicine’s ability to improve human health.
In April 2018, Glaxo SmithKline signed a strategic agreement to transfer its rare disease gene therapy portfolio to Orchard Therapeutics, which strengthens Orchard’s position as a global leader in gene therapy for rare diseases.
In May 2021 the researchers followed up 50 patients treated for ADA-SCID with OTL-101, and the results showed 100% survival. Over 95% of the patients had sustained expression of the ADA enzyme showing that the gene therapy was successful, after 2 to 3 years following the treatment.
Find out more
Top image: Professor Bobby Gaspar and Teigan, who received treatment for severe combined immunodeficiency. Credit: Great Ormond Street Hospital.