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Infants with a rare genetic condition putting their immune system at risk and making their immune system obsolete could have a new life, after eight patients with "bubble boy disease" saw the defense system of their Body restored through gene therapy developed by scientists at the National Institutes of Health and St. Jude Children's Research Hospital in Memphis, Tennessee.
The disease – called X-linked severe combined immunodeficiency (SCID) – occurs almost exclusively in boys and is caused by mutations in the IL2RG gene, responsible for ensuring the presence of a vital protein for growth and the maturation of developing immune cells. called lymphocytes is produced. Without functioning lymphocytes, which defend the body against pathogens, make antibodies and help regulate the immune system, smaller infections such as colds can be deadly.
A bone marrow transplant – although medically safe – in a genetically matched sibling may be curative, but patients do not always have an optimal donor. This disease, which occurs about 1 in 200,000 times, makes patients so susceptible to infections that they usually do not live beyond childhood without treatment.
On Wednesday, researchers published a report in the The New England Medical Journal detailing the safe and curative potential of their treatment in the context of a clinical trial in patients under two years of age. It involves extracting stem cells from the patient, using a modified version of the HIV virus to insert the missing IL2RG gene and re-injecting calls into the subject to restore the immune system. Prior to cell infusion, patients received a low dose of chemotherapy to prime the bone marrow for the production of fresh blood cells from genetically-corrected stem cells.
Harry Malech
A similar approach a few decades ago triggered leukemia in some patients – scientists suspect that this is because the vector has unintentionally activated genes that control cell growth. Therefore, the researchers said that the vector used in the study presented on Wednesday was designed to avoid this result. While other older approaches to gene therapy restored T cell function, they did not fully restore the function of other key immune cells, including B cells and natural killer (NK) cells, they added.
Normal levels of immune cells – including T cells, B cells, and NK cells – appeared three to four months after treatment in seven of the eight infants participating in the trial. The eighth patient initially had a small number of T cells, but their numbers increased following a second infusion of genetically modified stem cells.
The viral and bacterial infections that participants had before treatment were resolved afterwards, and four infants were also able to discontinue treatment with intravenous immunoglobulins – infusions of antibodies used to strengthen the immune system. # 39; immunity.
"The broad range of immune functions that our gene therapy approach has restored in infants with X-SCID – as well as in older children and young adults in our NIH study – is unprecedented," said Harry Malech. , Head of the Department of Genetic Immunotherapy. in the clinical immunology and microbiology laboratory of the National Institute of Allergy and Infectious Diseases (NIAID).
Malech co-led the development of the lentiviral gene therapy approach with Brian Sorrentino of St Jude, who died in late 2018.
St. Jude has licensed the therapy to Mustang Bio, a New York-based biotech, to develop it for commercial purposes as an MB-107. During the trial, a total of 10 infants received treatment, although the published data reflect the results of eight infants followed for a median of 16.4 months. The company's shares, MBIO $, soared more than 227 percent to $ 8.70 in pre-market trading on Thursday. The data presented Wednesday follow the positive results of the lawsuit published by Mustang last August.
A gene therapy developed by GSK $ GSK for a different form of SCID (Adenosine Deficiency Deficiency SCID (ADA)) was approved in Europe in 2016, but the UK drug maker has struggled to find clients (about 15 cases are diagnosed each year in Europe) expensive treatment, despite offering a money back guarantee. The main obstacle was limited access, as patients could only be treated in one center in Milan. Eventually, GSK abandoned gene therapy at Orchard Therapeutics in the UK.
The name "bubble boy disease" comes from a famous case of the 1970s, in which a Texas boy literally lived in a protective plastic bubble to create a sterile environment without germs. The affair also enters the cultural atmosphere with an episode of the popular sitcom Seinfeld, in which one of the main protagonists, George Costanza, is provoked by a boy named Donald who is afflicted with the disease (and who is wrapped in a bubble) during a game game. Trivial Pursuit. Things heat up and Donald tries to strangle George, who is visibly hot and disturbed, when, moments later, George's girlfriend inadvertently drops the bubble, resulting in a decidedly macabre end of the scene.
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