Vector integration is nonrandom and clustered and influences the fate of lymphopoiesis in SCID-X1 gene therapy.
Recent reports have challenged the notion that retroviruses and retroviral vectors integrate randomly into the host genome. These reports pointed to a strong bias toward integration in and near gene coding regions and, for gammaretroviral vectors, around transcription start sites. Here, we report the results obtained from a large-scale mapping of 572 retroviral integration sites (RISs) isolated from cells of 9 patients with X-linked SCID (SCID-X1) treated with a retrovirus-based gene therapy protocol. Our data showed that two-thirds of insertions occurred in or very near to genes, of which more than half were highly expressed in CD34(+) progenitor cells. Strikingly, one-fourth of all integrations were clustered as common integration sites (CISs). The highly significant incidence of CISs in circulating T cells and the nature of their locations indicate that insertion in many gene loci has an influence on cell engraftment, survival, and proliferation. Beyond the observed cases of insertional mutagenesis in 3 patients, these data help to elucidate the relationship between vector insertion and long-term in vivo selection of transduced cells in human patients with SCID-X1.
Deichmann
Annette
A
Institute for Molecular Medicine and Cell Research and Department of Internal Medicine I, German Cancer Research Center, University of Freiburg, Freiburg, Germany.
Hacein-Bey-Abina
Salima
S
Schmidt
Manfred
M
Garrigue
Alexandrine
A
Brugman
Martijn H
MH
Hu
Jingqiong
J
Glimm
Hanno
H
Gyapay
Gabor
G
Prum
Bernard
B
Fraser
Christopher C
CC
Fischer
Nicolas
N
Schwarzwaelder
Kerstin
K
Siegler
Maria-Luise
ML
de Ridder
Dick
D
Pike-Overzet
Karin
K
Howe
Steven J
SJ
Thrasher
Adrian J
AJ
Wagemaker
Gerard
G
Abel
Ulrich
U
Staal
Frank J T
FJ
Delabesse
Eric
E
Villeval
Jean-Luc
JL
Aronow
Bruce
B
Hue
Christophe
C
Prinz
Claudia
C
Wissler
Manuela
M
Klanke
Chuck
C
Weissenbach
Jean
J
Alexander
Ian
I
Fischer
Alain
A
von Kalle
Christof
C
Cavazzana-Calvo
Marina
M
D018952:Antigens, CD34; D049109:Cell Proliferation; D002470:Cell Survival / Q000235:genetics; D017988:Gammaretrovirus; D015316:Genetic Therapy; D005822:Genetic Vectors; D015894:Genome, Human; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D038041:Lymphopoiesis / Q000235:genetics*; D016254:Mutagenesis, Insertional; D040641:Quantitative Trait Loci; D013601:T-Lymphocytes; D013997:Time Factors; D016662:Virus Integration / Q000235:genetics*; D053632:X-Linked Combined Immunodeficiency Diseases / Q000235:genetics / Q000628:therapy*
D018952:Antigens, CD34