In this week’s Science, two Italian research groups reported on promising results from gene therapy clinical trials. In both studies, hematopoietic stem cells were removed from patients, then tranduced with lentiviral vectors encoding therapeutic genes and returned to the patients. For three children with the rare lysosomal storage disorder metachromatic leukodystrophy, which is caused by mutations in the ARSA gene, treatment appears to have halted progression of the disease.
Meanwhile, three children who received gene therapy for the immunodeficiency disorder Wiskott-Aldrich syndrome, which is caused by mutations in the WAS gene, experienced a lessening or even disappearance of their symptoms around two years after treatment. Importantly, there were no signs of lentiviral vector integration in any of the patients.