Preclinical Development of a Lentiviral Vector for Gene Therapy of X-Linked Severe Combined Immunodeficiency.

Abstract

X-linked severe combined immunodeficiency (SCID-X1) is caused by mutations in the interleukin-2 receptor γ chain gene (IL2RG), and it is characterized by profound defects in T, B, and natural killer (NK) cell functions. Transplantation of hematopoietic stem/progenitor cells (HSPCs) genetically corrected with early murine leukemia retrovirus (MLV)-derived gammaretroviral vectors showed restoration of T cell immunity in patients, but it resulted in vector-induced insertional oncogenesis. We developed a self-inactivating (SIN) lentiviral vector carrying a codon-optimized human IL2RG cDNA driven by the EF1α short promoter (EFS-IL2RG), and we tested its efficacy and safety in vivo by transplanting transduced Il2rg-deficient Lin- HSPCs in an Il2rg-/-/Rag2-/- mouse model. The study showed restoration of T, B, and NK cell counts in bone marrow and peripheral blood and normalization of thymus and spleen cellularity and architecture. High-definition insertion site analysis defined the EFS-IL2RG genomic integration profile, and it showed no sign of vector-induced clonal selection or skewing in primarily and secondarily transplanted animals. The study enables a phase I/II clinical trial aimed at restoring both T and B cell immunity in SCID-X1 children upon non-myeloablative conditioning.

• Authors: Valentina Poletti, Sabine Charrier, Guillaume Corre, Bernard Gjata, Alban Vignaud, Fang Zhang, Michael Rothe, Axel Schambach, H Bobby Gaspar, Adrian J Thrasher, Fulvio Mavilio
• Journal: Molecular therapy. Methods & clinical development (Mol Ther Methods Clin Dev) Vol. 9 Pg. 257-269 (Jun 15 2018) ISSN: 2329-0501 [Print] United States
• PMID: 29707600 (Publication Type: Journal Article)