Experimental gene therapy successfully revives immune systems in children with deadly disorder |

A new experimental gene therapy has successfully restored immune system function in children born with ADA-SCID, a rare and potentially fatal genetic immune disorder. Developed by researchers at UCLA, University College London, and Great Ormond Street Hospital, the therapy treated 59 out of 62 children. ADA-SCID is caused by mutations in the ADA gene, which is essential for immune function, leaving children highly vulnerable to infections. Traditional treatments, including bone marrow transplants or weekly enzyme injections, carry limitations and risks. This therapy offers hope by correcting the genetic defect in a child’s blood stem cells, allowing the immune system to rebuild and function normally over time.

Gene therapy restores immune system in children with ADA-SCID

The experimental gene therapy involves collecting a child’s blood stem cells, which generate all types of blood and immune cells. Scientists use a modified lentivirus to insert a healthy copy of the ADA gene into these stem cells. Once reinfused, the corrected cells begin producing functional immune cells capable of fighting infections. Immune system recovery begins soon after reinfusion but takes six to twelve months to reach normal levels.Severe combined immunodeficiency due to adenosine deaminase deficiency, or ADA-SCID, is a rare genetic disorder in which the body cannot produce a functional immune system. Without treatment, affected children face life-threatening infections and typically do not survive beyond two years. Standard therapies, including bone marrow transplants and enzyme replacement, have improved survival but come with long-term complications and logistical challenges.

Published in the New England Journal of Medicine, the study followed children treated between 2012 and 2019, representing the largest and longest follow-up for this type of gene therapy. With 474 patient-years of data, immune function remained stable in successfully treated children, and most adverse events were mild or related to routine preparatory procedures. Only three patients did not respond to the therapy and returned to standard treatments.More than half of the children received frozen preparations of corrected stem cells, which proved just as effective as fresh cells. Cryopreservation allows local collection and processing at distant manufacturing facilities, improving access for patients worldwide. This method also enables more precise dosing and thorough quality control before therapy administration.

Moving toward FDA approval

The UCLA team, supported by Rarity PBC and the California Institute for Regenerative Medicine, is now pursuing FDA approval. Clinical data strongly support approval, and efforts are underway to scale production under pharmaceutical-grade conditions. Researchers aim to make the therapy widely available within the next two to three years.Eleven-year-old Eliana Nachem of Virginia received the therapy as an infant after living in strict medical isolation. Today, she attends school, plays basketball, and enjoys a normal childhood. Her parents describe the infusion as a “rebirth,” reflecting the transformative impact of gene therapy on her life and the lives of many children with ADA-SCID.