Engineered human Tmpk fused with truncated cell-surface markers: versatile cell-fate control safety cassettes

Cell-fate control gene therapy (CFCGT)-based strategies can augment existing gene therapy and cell transplantation approaches by providing a safety element in the event of deleterious outcomes. Previously, we described a novel enzyme/prodrug combination for CFCGT. Here, we present results employing novel lentiviral constructs harboring sequences for truncated surface molecules (CD19 or low-affinity nerve growth factor receptor) directly fused to that CFCGT cDNA (TmpkF105Y). This confers an enforced one-to-one correlation between cell marking and eradication functions. In-vitro analysis demonstrated the full functionality of the fusion product. Next, low-dose 3'-azido-3'-deoxythymidine (AZT) administration to non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice injected with transduced clonal K562 cells suppressed tumor growth; furthermore, one integrated vector on average was sufficient to mediate cytotoxicity. Further, in a murine xenogeneic leukemia-lymphoma model we also demonstrated in-vivo control over transduced Raji cells. Finally, in a proof-of-principle study to examine the utility of this cassette in combination with a therapeutic cDNA, we integrated this novel CFCGT fusion construct into a lentivector designed for treatment of Fabry disease. Transduction with this vector restored enzyme activity in Fabry cells and retained AZT sensitivity. In addition, human Fabry patient CD34(+) cells showed high transduction efficiencies and retained normal colony-generating capacity when compared with the non-transduced controls. These collective results demonstrated that this novel and broadly applicable fusion system may enhance general safety in gene- and cell-based therapies.Fil: Scaife, Matthew. University of Toronto; CanadáFil: Pacienza, Natalia Alejandra. University Health Network. Ontario Cancer Institute; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Au, B. C. Y.. University Health Network. Ontario Cancer Institute; CanadáFil: Wang, J. C. M.. University Health Network. Ontario Cancer Institute; CanadáFil: Devine, S.. University of Toronto; CanadáFil: Scheid, E.. Mc Master University; CanadáFil: Lee, C. J.. University Health Network. Ontario Cancer Institute; CanadáFil: Lopez Perez, O.. University Health Network. Ontario Cancer Institute; CanadáFil: Neschadim, A.. University of Toronto; CanadáFil: Fowler, D. H.. National Institutes of Health; Estados UnidosFil: Foley, R.. Mc Master University; CanadáFil: Medin, J. A.. University of Toronto; Canadá. University Health Network. Ontario Cancer Institute; Canad