Treatment of SCID Due to ADA Deficiency With Autologous Cord Blood or Bone Marrow CD34+ Cells Transduced With a Human ADA Gene

This study will evaluate a new method for delivering gene transfer therapy to patients with severe combined immunodeficiency disease (SCID) due to a defective adenosine deaminase (ADA) gene. This gene codes for the adenosine deaminase enzyme, which is essential for the proper growth and function of infection-fighting white blood cells called T and B lymphocytes. Patients who lack this enzyme are vulnerable to frequent and severe infections.

Some patients with this disease receive enzyme replacement therapy with weekly injections of the drug PEG-ADA (ADAGEN). This drug may increase the number of immune cells and reduce infections, but it is not a cure. Gene transfer therapy, in which a normal ADA gene is inserted into the patient s cells, attempts to correct the underlying cause of disease. This therapy has been tried in a small number of patients with varying degrees of success. In this study, the gene will be inserted into the patient s stem cells (cells produced by the bone marrow that mature into the different blood components white cells, red cells and platelets).

Patients with ADA deficiency and SCID who are taking PEG-ADA and are not candidates for HLA-identical sibling donor bone marrow transplantation may be eligible for this study.

Participants will be admitted to the NIH Clinical Center for 2 to 3 days. Stem cells will be collected either from cord blood (in newborn patients) or from the bone marrow. The bone marrow procedure is done under light sedation or general anesthesia. It involves drawing a small amount of marrow through a needle inserted into the hip bone. The stem cells in the marrow will be grown in the laboratory and a normal human ADA gene will be transferred into them through a special type of disabled mouse virus. A few days later, the patient will receive the ADA-corrected cells through an infusion in the vein that will last from 10 minutes to 2 hours.

Patients will be evaluated periodically for immune function with blood tests, skin tests, and reactions to tetanus, diphtheria, H. influenza B and S. pneumoniae vaccinations. The survival of ADA-corrected cells will be monitored through blood tests. The number and amount of blood tests will depend on the patient s age, weight and health, but is expected that blood will not be drawn more than twice a month. Patients will also undergo bone marrow biopsy aspirate (as described above) twice a year. Patients will be followed once a year indefinitely to evaluate the long-term effects of therapy.