Gene transfer into hematopoietic stem cells by γ-retroviral vectors (RVs) is an effective treatment for inherited blood disorders, although potentially limited by the risk of insertional mutagenesis. We evaluated the genomic impact of RV integration in T lymphocytes from adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) patients 10 to 30 months after infusion of autologous, genetically corrected CD34+ cells. Expression profiling on ex vivo T-cell bulk population revealed no difference with respect to healthy controls. To assess the effect of vector integration on gene expression at the single-cell level, primary T-cell clones were isolated from 2 patients. T-cell clones harbored either 1 (89.8%) or 2 (10.2%) vector copies per cell and displayed partial to full correction of ADA expression, purine metabolism, and T-cell receptor-driven functions. Analysis of RV integration sites indicated a high diversity in T-cell origin, consistently with the polyclonal T-cell receptor-Vβ repertoire. Quantitative transcript analysis of 120 genes within a 200-kb window around RV integration sites showed modest (2.8-to 5.2-fold) dysregulation of 5.8% genes in 18.6% of the T-cell clones compared with controls. Nonetheless, affected clones maintained a stable phenotype and normal in vitro functions. These results confirm that RV-mediated gene transfer for ADA-SCID is safe, and provide crucial information for the development of future gene therapy protocols. The trials described herein have been registered at http://www.clinicaltrials. gov as #NCT00598481 and #NCT00599781.
Integration of retroviral vectors induces minor changes in the transcriptional activity of T cells from ADA-SCID patients treated with gene therapy / B. Cassani, E. Montini, G. Maruggi, A. Ambrosi, M. Mirolo, S. Selleri, E. Biral, I. Frugnoli, V. Hernandez-Trujillo, C. Di Serio, M.G. Roncarolo, L. Naldini, F. Mavilio, A. Aiuti. - In: BLOOD. - ISSN 0006-4971. - 114:17(2009 Oct), pp. 3546-3556. [10.1182/blood-2009-02-202085]
Integration of retroviral vectors induces minor changes in the transcriptional activity of T cells from ADA-SCID patients treated with gene therapy
B. CassaniPrimo
;
2009
Abstract
Gene transfer into hematopoietic stem cells by γ-retroviral vectors (RVs) is an effective treatment for inherited blood disorders, although potentially limited by the risk of insertional mutagenesis. We evaluated the genomic impact of RV integration in T lymphocytes from adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) patients 10 to 30 months after infusion of autologous, genetically corrected CD34+ cells. Expression profiling on ex vivo T-cell bulk population revealed no difference with respect to healthy controls. To assess the effect of vector integration on gene expression at the single-cell level, primary T-cell clones were isolated from 2 patients. T-cell clones harbored either 1 (89.8%) or 2 (10.2%) vector copies per cell and displayed partial to full correction of ADA expression, purine metabolism, and T-cell receptor-driven functions. Analysis of RV integration sites indicated a high diversity in T-cell origin, consistently with the polyclonal T-cell receptor-Vβ repertoire. Quantitative transcript analysis of 120 genes within a 200-kb window around RV integration sites showed modest (2.8-to 5.2-fold) dysregulation of 5.8% genes in 18.6% of the T-cell clones compared with controls. Nonetheless, affected clones maintained a stable phenotype and normal in vitro functions. These results confirm that RV-mediated gene transfer for ADA-SCID is safe, and provide crucial information for the development of future gene therapy protocols. The trials described herein have been registered at http://www.clinicaltrials. gov as #NCT00598481 and #NCT00599781.File | Dimensione | Formato | |
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