A joint UCL–UCLA clinical program reported multi‑year data showing their lentiviral gene therapy for ADA‑SCID produced immune reconstitution in treated children with a roughly 95% success rate and no serious long‑term safety signals, investigators said. The team published follow‑up results in The New England Journal of Medicine and discussed translational outcomes with BioXconomy. Researchers Claire Booth and Donald Kohn led this effort using an autologous hematopoietic stem cell approach to restore adenosine deaminase activity. The report documents durable immune recovery without the need for enzyme‑replacement therapy or matched donor transplants in most patients. If replicated broadly, the data strengthen the case for gene therapy as a curative alternative to enzyme replacement and mismatched transplants for ADA‑SCID and provide a regulatory and commercial roadmap for similar rare‑disease launches.