Molecular Therapy: Methods & Clinical Development (Jun 2020)

Successful Preclinical Development of Gene Therapy for Recombinase-Activating Gene-1-Deficient SCID

  • Laura Garcia-Perez,
  • Marja van Eggermond,
  • Lieke van Roon,
  • Sandra A. Vloemans,
  • Martijn Cordes,
  • Axel Schambach,
  • Michael Rothe,
  • Dagmar Berghuis,
  • Chantal Lagresle-Peyrou,
  • Marina Cavazzana,
  • Fang Zhang,
  • Adrian J. Thrasher,
  • Daniela Salvatori,
  • Pauline Meij,
  • Anna Villa,
  • Jacques J.M. Van Dongen,
  • Jaap-Jan Zwaginga,
  • Mirjam van der Burg,
  • H. Bobby Gaspar,
  • Arjan Lankester,
  • Frank J.T. Staal,
  • Karin Pike-Overzet

Journal volume & issue
Vol. 17
pp. 666 – 682

Abstract

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Recombinase-activating gene-1 (RAG1)-deficient severe combined immunodeficiency (SCID) patients lack B and T lymphocytes due to the inability to rearrange immunoglobulin and T cell receptor genes. Gene therapy is an alternative for those RAG1-SCID patients who lack a suitable bone marrow donor. We designed lentiviral vectors with different internal promoters driving codon-optimized RAG1 to ensure optimal expression. We used Rag1−/− mice as a preclinical model for RAG1-SCID to assess the efficacy of the various vectors. We observed that B and T cell reconstitution directly correlated with RAG1 expression. Mice with low RAG1 expression showed poor immune reconstitution; however, higher expression resulted in phenotypic and functional lymphocyte reconstitution comparable to mice receiving wild-type stem cells. No signs of genotoxicity were found. Additionally, RAG1-SCID patient CD34+ cells transduced with our clinical RAG1 vector and transplanted into NSG mice led to improved human B and T cell development. Considering this efficacy outcome, together with favorable safety data, these results substantiate the need for a clinical trial for RAG1-SCID.

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