In vivo T-cell dynamics during immune reconstitution after hematopoietic stem cell gene therapy in adenosine deaminase severe combined immune deficiency

Abstract

Background: Gene therapy (GT) with hematopoietic stem cells is a promising treatment for inherited immunodeficiencies. Objectives: Limited information is available on the relative contribution of de novo thymopoiesis and peripheral expansion to T-cell reconstitution after GT as well as on the potential effects of gene transfer on hematopoietic stem cells and lymphocyte replicative lifespan. We studied these issues in patients affected by adenosine deaminase severe combined immune deficiency after low-intensity conditioning and reinfusion of retrovirally transduced autologous CD34 1 cells. Methods: Immunophenotype, proliferative status, telomere length, and T-cell receptor excision circles were investigated at early and late time points (up to 9 years) after GT treatment. Control groups consisted of pediatric healthy donors and patients undergoing allogeneic bone marrow transplantation (BMT). Results: We observed no telomere shortening in the bone marrow compartment and in granulocytes, whereas peripheral blood naive T cells from both GT and BMT patients showed a significant reduction in telomere length compared with healthy controls. This was in agreement with the presence of a high fraction of actively cycling naive and memory T cells and lower T-cell receptor excision circles. Conclusion: These data indicate that T-cell homeostatic expansion contributes substantially to immune reconstitution, like BMT, and is not associated with senescence in the stem cell compartment. (J Allergy Clin Immunol 2011;127:1368-75.)

Update on the safety and efficacy of retroviral gene therapy for immunodeficiency due to adenosine deaminase deficiency

“…Previously, transplant with autologous gene-corrected hematopoietic stem cells in 10 patients with ADA-SCID detoxified purine metabolites, increased T-cell counts, and normalized T-cell function during a clinical follow-up period ranging from 1.8 to 8 years. [16][17][18] Here, we expand on those data with long-term (2.3 to 13.4 years; median, 6.9 years) safety and efficacy results in those and 8 additional patients.…”

“…• Survival was 100% for 18 patients with ADA-SCID treated with genetically modified CD34 1 cells (2.3-13.4 years follow up; median, 6.9 years).…”

B-cell development and functions and therapeutic options in adenosine deaminase–deficient patients

“…The protocol for the purification of different cell subsets and qPCR for gene-corrected cells was performed as previously described. E4 The purity of CD19 + B cells was greater than 90%.…”

IL-7 and IL-15 instruct the generation of human memory stem T cells from naive precursors

“…Real-time quantitative PCR (qPCR) for single-joint TCR excision circles (sjTRECs) was performed as described previously, 19 using GAPDH as a control to standardize DNA content. Briefly, amplification reactions were performed in a final volume of 25 L containing 50 ng of genomic DNA isolated from the different T-cell subsets, TaqMan universal PCR master mix (PerkinElmer/Applied Biosystems), and the appropriate primers and probes.…”