There are multiple gene mutations associated with severe combined immunodeficiency (SCID), a rare genetic disorder which severely inhibits – or stops – immune function. But according to New Atlas, an experimental lentiviral gene therapy could be extremely efficacious in treating SCID. After treating 50 patients with the therapy, targeted towards patients with ADA gene mutations (ADA-SCID), researchers highlighted the treatment’s long-term benefits. Check out the full findings published in the New England Journal of Medicine.

Lentiviral Gene Therapy for ADA-SCID

Prior treatments for patients with ADA-SCID include Strimvelis, which is also a gene therapy. However, Orchard Therapeutics, the therapy’s developer, stopped dosing within a clinical trial after one patient developed leukemia. Thus, there are concerns that an additional effective and safe option is needed.

In this new gene therapy, the study authors explain that the therapy is:

an investigational gene therapy composed of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) transduced ex vivo with a self-inactivating lentiviral vector encoding human ADA.

So it uses a lentiviral vector to deliver a functional ADA gene to patients. Within the study, 50 patients with ADA-SCID were treated using this gene therapy. Next, the overall survival rate was monitored for 24-36 months (2-3 years) following treatment. Because this is a gene therapy, it only needs to be administered once. Findings included:

• Overall survival rate was 100% by the end of the follow-up period, meaning all 50 patients remained alive.
• 48 out of 50 patients saw persistent and sustained engraftment of hematopoietic stem cells. Additionally, this same group was able to stop immunoglobulin-replacement therapy by the end of the follow-up period.
  • Note: Engraftment is the process of when transplanted cells begin to grow and help create healthy blood cells.
• Altogether, the gene therapy was found to be relatively safe and well-tolerated. Side effects and adverse reactions were minimal.

While this gene therapy is not yet commercially available, it does show the potential shifts within the ADA-SCID treatment realm.

Severe Combined Immunodeficiency (SCID)

Altogether, severe combined immunodeficiency (SCID) consists of a group of rare genetic disorders caused by a variety of gene mutations. In each case, the genetic mutation alters the way immune T and B cells function, preventing them from adequately fighting infection. Because the immune system isn’t properly working, patients are at an extremely heightened risk of infection and other illnesses. An estimated 1 in every 100,000 American births has SCID. Typically, SCID is more common in those with Turkish, Navajo, or Apache heritage.

While infants with SCID may initially appear healthy at birth, symptoms often appear soon after. Unfortunately, SCID can be fatal within the first few years of life without some immune-restoring therapies. Symptoms include:

• Treatment-averse infections
• Failure to thrive
• Pneumonia
• Chronic diarrhea
• Recurrent ear infections
• Frequent and serious respiratory infections
• Meningitis
• Hepatitis
• Oral thrush
• Chronic skin infections
• Blood infections