Thymidine kinase suicide gene-mediated ganciclovir ablation of autologous gene-modified rhesus hematopoiesis.
Despite the genotoxic complications encountered in clinical gene therapy trials for primary immunodeficiency diseases targeting hematopoietic cells with integrating vectors; this strategy holds promise for the cure of several monogenic blood, metabolic and neurodegenerative diseases. In this study, we asked whether the inclusion of a suicide gene in a standard retrovirus vector would allow elimination of vector-containing stem and progenitor cells and their progeny in vivo following transplantation, using our rhesus macaque transplantation model. Following stable engraftment with autologous CD34(+) cells transduced with a retrovirus vector encoding a highly sensitive modified Herpes simplex virus thymidine kinase SR39, the administration of the antiviral prodrug ganciclovir (GCV) was effective in completely eliminating vector-containing cells in all hematopoietic lineages in vivo. The sustained absence of vector-containing cells over time, without additional GCV administration, suggests that the ablation of TkSR39 GCV-sensitive cells occurred in the most primitive hematopoietic long-term repopulating stem or progenitor cell compartment. These results are a proof-of-concept that the inclusion of a suicide gene in integrating vectors, in addition to a therapeutic gene, can provide a mechanism for later elimination of vector-containing cells, thereby increasing the safety of gene transfer.
Hematology Branch, The National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA.
Cecilia N
CN
Barese
Allen E
AE
Krouse
Mark E
ME
Metzger
Connor A
CA
King
Catia
C
Traversari
Frank C
FC
Marini
Robert E
RE
Donahue
Cynthia E
CE
Dunbar
D000818:Animals; D000998:Antiviral Agents / Q000627:therapeutic use; D004261:DNA Replication; D015774:Ganciclovir / Q000627:therapeutic use*; D041722:Genes, Transgenic, Suicide; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D006410:Hematopoiesis / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000166:cytology; D008253:Macaca mulatta; D012190:Retroviridae / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics*; D014161:Transduction, Genetic
D000998:Antiviral Agents; D013937:Thymidine Kinase; D015774:Ganciclovir