Landmark UCL Study Confirms Long-Term Safety and Efficacy of Gene Therapy for ADA-SCID

October 2025 · London, UK — A new study led by researchers at University College London (UCL) and Great Ormond Street Hospital has confirmed the long-term safety and efficacy of gene therapy for treating adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID), a rare and life-threatening inherited immune disorder.

The therapy—originally developed at UCL and refined through international collaboration—restores immune function in children born without a working immune system. Published in The Lancet Haematology, the 8-year follow-up shows stable immune recovery and no serious adverse events, marking one of the longest and most comprehensive post-treatment evaluations in gene therapy.

Restoring Immunity in Children with No Defense

ADA-SCID is caused by mutations in the ADA gene, leaving infants extremely vulnerable to infections. Traditional treatments such as enzyme replacement or bone marrow transplantation face limitations including donor dependence and high cost.

In the UCL-led trial, scientists extracted patients’ hematopoietic stem cells, inserted a functional ADA gene using a lentiviral vector, and re-infused the corrected cells.

Results showed that more than 95 % of patients maintained full immune reconstitution for over eight years. Importantly, no cases of vector-related leukemia were observed, addressing historical safety concerns from earlier retroviral approaches.

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Toward Broader Clinical Access

The research also highlighted the feasibility of producing frozen, ready-to-use cell batches—critical for making the therapy more widely available.

Experts note that this work underscores the growing need for advanced biomanufacturing capabilities to scale such personalized therapies safely and efficiently.

In the manufacturing domain, next-generation CDMOs like Hillgene are exploring similar lentiviral and stem-cell processing platforms to enhance process consistency and regulatory compliance.

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Source: University College London News, “Landmark gene therapy study shows safety in children,” October 2025.