Multilineage hematopoietic reconstitution without clonal selection in ADA-SCID patients treated with stem cell gene therapy.
Gene transfer into HSCs is an effective treatment for SCID, although potentially limited by the risk of insertional mutagenesis. We performed a genome-wide analysis of retroviral vector integrations in genetically corrected HSCs and their multilineage progeny before and up to 47 months after transplantation into 5 patients with adenosine deaminase-deficient SCID. Gene-dense regions, promoters, and transcriptionally active genes were preferred retroviral integrations sites (RISs) both in preinfusion transduced CD34(+) cells and in vivo after gene therapy. The occurrence of insertion sites proximal to protooncogenes or genes controlling cell growth and self renewal, including LMO2, was not associated with clonal selection or expansion in vivo. Clonal analysis of long-term repopulating cell progeny in vivo revealed highly polyclonal T cell populations and shared RISs among multiple lineages, demonstrating the engraftment of multipotent HSCs. These data have important implications for the biology of retroviral vectors, the dynamics of genetically modified HSCs, and the safety of gene therapy.
San Raffaele Telethon Institute for Gene Therapy (HSR-TIGET), Milan, Italy. a.aiuti@hsr.it
Alessandro
A
Aiuti
Barbara
B
Cassani
Grazia
G
Andolfi
Massimiliano
M
Mirolo
Luca
L
Biasco
Alessandra
A
Recchia
Fabrizia
F
Urbinati
Cristina
C
Valacca
Samantha
S
Scaramuzza
Memet
M
Aker
Shimon
S
Slavin
Matteo
M
Cazzola
Daniela
D
Sartori
Alessandro
A
Ambrosi
Clelia
C
Di Serio
Maria Grazia
MG
Roncarolo
Fulvio
F
Mavilio
Claudio
C
Bordignon
D048868:Adaptor Proteins, Signal Transducing; D000243:Adenosine Deaminase / Q000235:genetics; D018952:Antigens, CD34; D002675:Child, Preschool; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D015316:Genetic Therapy; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D007223:Infant; D060588:LIM Domain Proteins; D008297:Male; D008667:Metalloproteins / Q000235:genetics; D039902:Multipotent Stem Cells / Q000378:metabolism; D016254:Mutagenesis, Insertional; D011518:Proto-Oncogene Proteins; D012190:Retroviridae; D012307:Risk Factors; D016511:Severe Combined Immunodeficiency / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D013601:T-Lymphocytes / Q000378:metabolism; D014182:Transplantation, Autologous; D016662:Virus Integration / Q000235:genetics*
D048868:Adaptor Proteins, Signal Transducing; D018952:Antigens, CD34; D004268:DNA-Binding Proteins; D060588:LIM Domain Proteins; C085117:LMO2 protein, human; D008667:Metalloproteins; D011518:Proto-Oncogene Proteins; D000243:Adenosine Deaminase