Hematopoietic stem cell gene transfer in a tumor-prone mouse model uncovers low genotoxicity of lentiviral vector integration.
Insertional mutagenesis represents a major hurdle to gene therapy and necessitates sensitive preclinical genotoxicity assays. Cdkn2a-/- mice are susceptible to a broad range of cancer-triggering genetic lesions. We exploited hematopoietic stem cells from these tumor-prone mice to assess the oncogenicity of prototypical retroviral and lentiviral vectors. We transduced hematopoietic stem cells in matched clinically relevant conditions, and compared integration site selection and tumor development in transplanted mice. Retroviral vectors triggered dose-dependent acceleration of tumor onset contingent on long terminal repeat activity. Insertions at oncogenes and cell-cycle genes were enriched in early-onset tumors, indicating cooperation in tumorigenesis. In contrast, tumorigenesis was unaffected by lentiviral vectors and did not enrich for specific integrants, despite the higher integration load and robust expression of lentiviral vectors in all hematopoietic lineages. Our results validate a much-needed platform to assess vector safety and provide direct evidence that prototypical lentiviral vectors have low oncogenic potential, highlighting a major rationale for application to gene therapy.
Montini
Eugenio
E
San Raffaele-Telethon Institute for Gene Therapy, via Olgettina 58, 20132, Milan, Italy.
Cesana
Daniela
D
Schmidt
Manfred
M
Sanvito
Francesca
F
Ponzoni
Maurilio
M
Bartholomae
Cynthia
C
Sergi Sergi
Lucia
L
Benedicenti
Fabrizio
F
Ambrosi
Alessandro
A
Di Serio
Clelia
C
Doglioni
Claudio
C
von Kalle
Christof
C
Naldini
Luigi
L
D000818:Animals; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005260:Female; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D016086:Lentivirus / Q000235:genetics*; D051379:Mice; D009152:Mutagenicity Tests / Q000379:methods*; D009369:Neoplasms / Q000235:genetics* / Q000628:therapy / Q000821:virology*; D014162:Transfection / Q000379:methods; D016662:Virus Integration