Gene Therapy Restores Immune Function in 95% of ADA-SCID Children

An experimental gene therapy developed by researchers at UCLA, University College London, and Great Ormond Street Hospital has achieved notable success in restoring immune function in children with ADA-SCID, a rare genetic disorder. According to long-term follow-up data published on August 28, 2026, in the New England Journal of Medicine, 59 of the 62 children treated with this gene therapy have demonstrated restored and maintained immune system function. This represents a 95% success rate, marking a significant advancement in treating this severe condition, which can lead to life-threatening infections if left untreated. ADA-SCID, or severe combined immunodeficiency due to adenosine deaminase deficiency, is caused by mutations in the ADA gene, which is essential for immune function. Children with ADA-SCID face serious health risks, as everyday activities can expose them to dangerous infections. Traditional treatments, including bone marrow transplants and weekly enzyme injections, come with limitations.

The gene therapy offers a new approach: it involves collecting a child’s blood stem cells and using a modified lentivirus to deliver a healthy copy of the ADA gene back into the patient’s body. This process enables the production of functional immune cells capable of fighting infections. The implementation of this innovative therapy involved treating children from 2012 to 2019, with long-term follow-up data providing insights into its durability and safety. Senior author Dr. Donald Kohn from UCLA, along with co-first authors Dr. Katelyn Masiuk and Dr. Claire Booth, reported stable immune function beyond the initial recovery period, with no treatment-limiting complications noted. This study represents the largest and longest follow-up of a gene therapy for ADA-SCID to date, comprising 474 total patient-years of follow-up data. The results are encouraging, showing that the therapy remains effective and safe over time.

Beyond the individual health benefits, this gene therapy has significant implications for the broader medical landscape. The successful restoration of immune function in these children reduces their risk of severe infections and enhances their quality of life. Additionally, the therapy's success with frozen preparations of corrected stem cells indicates a promising avenue for making this treatment more accessible to patients globally. This method allows for stem cells to be collected locally, processed in specialized facilities, and shipped back to hospitals, reducing the need for families to travel long distances for treatment. Looking forward, the researchers are focused on obtaining FDA approval for this gene therapy. With support from various organizations, including the California Institute for Regenerative Medicine, the UCLA team is working to finalize the necessary steps for regulatory approval. The goal is to make this innovative treatment available to patients within the next two to three years. The successful outcomes observed in this study not only highlight the potential of gene therapy for ADA-SCID but also pave the way for future advancements in treating other genetic disorders.