ADA Gene Transfer Into Hematopoietic Stem/Progenitor Cells for the Treatment of ADA-SCID
Status:
Completed
Trial end date:
2019-06-19
Target enrollment:
Participant gender:
Summary
This is a phase I/II protocol to evaluate the safety and efficacy of ADA gene transfer into
hematopoietic stem/progenitor cells for the treatment of adenosine deaminase
(ADA)-deficiency. This condition is an autosomal recessive form of Severe Combined
Immunodeficiency (SCID) characterized by impaired immune responses, recurrent infections,
failure to thrive and systemic toxicity due to accumulation of purine metabolites.
Transplants from an human leukocyte-antigen (HLA)-identical sibling donor is the treatment of
choice, but available for a minority of patients. The use of alternative bone marrow donors
or enzyme replacement therapy is associated with important drawbacks. The drug product
studied in this protocol consists of autologous cluster of differentiation (CD)34+
hematopoietic stem/progenitor cells engineered ex vivo with a retroviral vector encoding the
therapeutic gene ADA. The engineered CD34+ cells are infused following a nonmyeloablative
conditioning with busulfan to make space in the bone marrow. The study objectives are: a) to
evaluate the safety and the clinical efficacy of gene therapy, in the absence of enzyme
replacement therapy; b) to evaluate the biological activity (engraftment, ADA expression) of
ADA transduced CD34+ cells and their hematopoietic progeny. c) to evaluate the immunological
reconstitution and purine metabolism after gene therapy.