[Study of T cell-directed gene transfer for a patient with ADA deficiency]

We have been undertaking the gene therapy for a 6 year-old boy with ADA deficiency and performed 11 cycles of the infusion of the peripheral T cells transduced with retroviral vector LASN since August 8th 1995. The percentage of the peripheral blood lymphocytes carrying the transduced ADA gene has remained stable at 10% to 20% since the 4th infusion. ADA enzyme activity in his circulating T cells increased to levels comparable to 1/3 of a heterozygous carrier individual and was associated with increased T lymphocytes counts and improvement in both humoral and cellular immune function. The results obtained in this clinical study support the usefulness of T lymphocyte-directed gene transfer in the treatment of ADA deficiency.