Gene therapy for primary immunodeficiencies: current status and future prospects.

Abstract

Gene therapy using autologous haematopoietic stem cells offers a valuable treatment option for patients with primary immunodeficiencies who do not have access to an HLA-matched donor, although such treatments have not been without their problems. This review details gene therapy trials for X-linked and adenosine deaminase (ADA)-deficient severe combined immunodeficiency (SCID), Wiskott-Aldrich syndrome (WAS) and chronic granulomatous disease (CGD). X-linked SCID was chosen for gene therapy because of previous 'natural' genetic correction through a reversion event in a single lymphoid precursor, demonstrating limited thymopoiesis and restricted T-lymphocyte receptor repertoire, showing selective advantage of progenitors possessing the wild-type gene. In early studies, patients were treated with long terminal repeats-intact gamma-retroviral vectors, without additional chemotherapy. Early results demonstrated gene-transduced cells, sustained thymopoiesis, and a diverse T-lymphocyte repertoire with normal function. Serious adverse effects were subsequently reported in 5 of 20 patients, with T-lymphocyte leukaemia developing, secondary to the viral vector integrating adjacent to a known oncogene. New trials using self-inactivating gamma-retroviral vectors are progressing. Trials for ADA-SCID using gamma-retroviral vectors have been successful, with no similar serious adverse effects reported; trials using lentiviral vectors are in progress. Patients with WAS and CGD treated with early gamma-retroviral vectors have developed similar lymphoproliferative adverse effects to those seen in X-SCID--current trials are using new-generation vectors. Targeted gene insertion using homologous recombination of corrected gene sequences by cellular DNA repair pathways following targeted DNA breakage will improve efficacy and safety of gene therapy. A number of new techniques are discussed.

• Authors: Waseem Qasim, Andrew R Gennery
• Journal: Drugs (Drugs) Vol. 74 Issue 9 Pg. 963-9 (Jun 2014) ISSN: 1179-1950 [Electronic] New Zealand
• PMID: 24848753 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Review)

Topics

• Genetic Therapy (methods, trends)
• Hematopoietic Stem Cell Transplantation
• Humans
• Immunologic Deficiency Syndromes (genetics, therapy)
• Transplantation, Autologous