title: Hematopoietic stem cell gene transfer in a tumor-prone mouse model uncovers low genotoxicity of lentiviral vector integration.
abstract: 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.
authors.affiliation: San Raffaele-Telethon Institute for Gene Therapy, via Olgettina 58, 20132, Milan, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Montini
authors.forename: Daniela
authors.initials: D
authors.lastname: Cesana
authors.forename: Manfred
authors.initials: M
authors.lastname: Schmidt
authors.forename: Francesca
authors.initials: F
authors.lastname: Sanvito
authors.forename: Maurilio
authors.initials: M
authors.lastname: Ponzoni
authors.forename: Cynthia
authors.initials: C
authors.lastname: Bartholomae
authors.forename: Lucia
authors.initials: L
authors.lastname: Sergi Sergi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Benedicenti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ambrosi
authors.forename: Clelia
authors.initials: C
authors.lastname: Di Serio
authors.forename: Claudio
authors.initials: C
authors.lastname: Doglioni
authors.forename: Christof
authors.initials: C
authors.lastname: von Kalle
authors.forename: Luigi
authors.initials: L
authors.lastname: Naldini
mesh_terms: 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