The ADA-SCID gene therapy drug will be producted and distributed by Telethon

Also known as "bubble baby" disease, ADA-SCID (an acronym for adenosine-deaminase deficiency combined severe immune deficiency) is a very rare, life-threatening genetic disorder in which a defective gene blocks the production of an essential enzyme called adenosine deaminase (ADA), which is necessary for the production and maturation of lymphocytes, a particular type of white blood cell. 

Children born with ADA-SCID: 

• do not have a healthy immune system, so they cannot fight off common infections that can be fatal;
• are forced to live in a sterile and isolated environment. 

The annual incidence is estimated to be between 1/375,000 and 1/660,000 births. Based on data on new births in the European Union (about 4 million per year), it is estimated that between 6 and 11 babies are born with the condition each year in the 27 EU countries.

"The research that enabled us to develop this gene therapy began more than 25 years ago. The result is the fruit of the extraordinary work of the Institute's researchers and clinicians, as well as the support of the Telethon Foundation and all donors.

In light of the benefits we have seen over the years in our little patients, who are now getting older, we can only rejoice that this gene therapy will continue to be available," says Prof. Alessandro Aiuti, deputy director and head of clinical research at the Institute. 

Gene therapy for ADA-SCID is administered once in a lifetime. The gene therapy drug is prepared from hematopoietic stem cells taken from the patient himself, placed in contact with a viral-derived vector containing a corrected version of the defective gene in patients (ADA) that is able to restore production of the protein missing due to the genetic defect. Re-infused into the blood, the cells thus corrected are able to: 

• differentiate into previously missing elements (lymphocytes);
• defend the organism against infection.

Today there are several treatment options for ADA-SCID. The first choice is hematopoietic stem cell transplantation from a matched family donor, which can cure the disease but is available in less than 20% of cases. When this type of therapy is not feasible, gene therapy is a therapeutic option: it relies on a single administration of stem cells with the correct gene, which are taken from the same patient's bone marrow, greatly reducing the possible transplant reactions against the host. 

In the absence of these options, transplantation from a registry-matched or partially matched donor can be opted for, with a potentially increased risk of incurring the transplantation reaction against the host (GvHD), infection, and other complications that can even be fatal in some cases. 

Finally, enzyme replacement therapy is available, that is, periodic intravenous administration of the missing artificially produced enzyme, which is usually administered for limited periods of time pending definitive treatment such as transplantation or gene therapy.