title: Cell fate control gene therapy based on engineered variants of human deoxycytidine kinase.
abstract: The safety of cell therapy applications can be enhanced by the introduction of Cell Fate Control (CFC) elements, which encode pharmacologically controlled cellular suicide switches. CFC Gene Therapy (CFCGT) offers the possibility of establishing control over gene-modified cells (GMCs) with regards to their proliferation, differentiation, or function. However, enzymes commonly employed in these approaches often possess poor kinetics and high immunogenicity. We describe a novel CFCGT system based on engineered variants of human deoxyCytidine Kinase (dCK) that overcomes limitations of current modalities. Mutants of dCK with rationally designed active sites that make them thymidine-activating were stably introduced into cells by recombinant lentiviral vectors (LVs). Transduced cells maintained growth kinetics and function. These dCK mutants efficiently activate bromovinyl-deoxyuridine (BVdU), L-deoxythymidine (LdT), and L-deoxyuridine (LdU), which are otherwise not toxic to wild-type cells. We show that mutant dCK-expressing Jurkat, Molt-4, and U87mg cells could be efficiently eliminated in vitro and in xenogeneic leukemia and tumor models in vivo. We also describe a fusion construct of the thymidine-activating dCK to the cytoplasmic tail-truncated LNGFR molecule and applications to in vivo eradication of primary human T cells. This novel CFCGT system offers unique plasticity with respect to the wide range of prodrugs it can potentiate, and can be used as a reliable safety switch in cell and gene therapy.
authors.affiliation: Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Anton
authors.initials: A
authors.lastname: Neschadim
authors.forename: James C M
authors.initials: JC
authors.lastname: Wang
authors.forename: Takeya
authors.initials: T
authors.lastname: Sato
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Fowler
authors.forename: Arnon
authors.initials: A
authors.lastname: Lavie
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Medin
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000008:administration & dosage; D020134:Catalytic Domain; D045744:Cell Line, Tumor; D003842:Deoxycytidine Kinase / Q000235:genetics* / Q000378:metabolism; D003857:Deoxyuridine / Q000008:administration & dosage; D004789:Enzyme Activation / Q000187:drug effects; D005818:Genetic Engineering; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009369:Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D061251:Primary Cell Culture; D011355:Prodrugs / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013936:Thymidine / Q000008:administration & dosage / Q000235:genetics; D014161:Transduction, Genetic; D023041:Xenograft Model Antitumor Assays
chemical_list: D011355:Prodrugs; D003842:Deoxycytidine Kinase; D001973:Bromodeoxyuridine; D013936:Thymidine; D003857:Deoxyuridine