Correction of SCID-X1 using an enhancerless Vav promoter.
The efficacy of gene therapy for the treatment of inherited immunodeficiency has been highlighted in recent clinical trials, although in some cases complicated by insertional mutagenesis and silencing of vector genomes through methylation. To minimize these effects, we have evaluated the use of regulatory elements that confer reliability of gene expression, but also lack potent indiscriminate enhancer activity. The Vav1 proximal promoter is particularly attractive in this regard and may be useful in situations where high-level or complex regulation of gene expression is not necessary. X-linked severe combined immunodeficiency (SCID-X1) is a good candidate for such an approach, particularly as there may be additional disease-related intrinsic risks of leukemogenesis, and where safety is therefore a paramount concern. We have tested whether lentiviral vectors expressing the common cytokine receptor gamma chain under the control of the proximal Vav1 gene promoter are effective for correction of signaling defects and the disease phenotype. Despite low-level gene expression, we observed near-complete restoration of cytokine-mediated STAT5 phosphorylation in a model cell line. Furthermore, at low vector copy number, highly effective T- and B-lymphocyte reconstitution was achieved in vivo in a murine model of SCID-X1, in both primary and secondary graft recipients. This vector configuration deserves further evaluation and consideration for future clinical trials.
Almarza
E
E
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas y Centro de Investigación Biomédica en Red de Enfermedades Raras, 28040 Madrid, España.
Zhang
F
F
Santilli
G
G
Blundell
M P
MP
Howe
S J
SJ
Thornhill
S I
SI
Bueren
J A
JA
Thrasher
A J
AJ
D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000235:genetics; D023061:Gene Order; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D057809:HEK293 Cells; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D053631:Interleukin Receptor Common gamma Subunit / Q000235:genetics* / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051567:Proto-Oncogene Proteins c-vav / Q000235:genetics*; D015398:Signal Transduction; D053632:X-Linked Combined Immunodeficiency Diseases / Q000235:genetics / Q000628:therapy
D053631:Interleukin Receptor Common gamma Subunit; D007376:Interleukin-2; D051567:Proto-Oncogene Proteins c-vav; C496618:VAV1 protein, human