title: Characterization of human T lymphocytes engineered to express interleukin-15 and herpes simplex virus-thymidine kinase.
abstract: BACKGROUND
  Preclinical studies have demonstrated that tumor-reactive T cells expressing the interleukin (IL)-15 transgene had enhanced activity. Gene therapy strategies using IL-15 should include a safety mechanism in anticipation of possible adverse effects because IL-15 overexpression has been implicated in autoimmune disorders and may be involved in the pathogenesis of some leukemias. We developed a retroviral vector carrying both IL-15 and the herpes simplex virus-thymidine kinase (HSV-TK) suicide gene and characterized its application in the transduction of human T lymphocytes.
  
  
  METHODS
  A retroviral vector carrying IL-15 and HSV-TK genes was optimized for the transduction of human T lymphocytes. IL-15 production was measured by enzyme-linked immunosorbent assay. Thymidine incorporation and cell viability assays were used to assess the efficacy of the HSV-TK suicide gene. Genetically modified tumor-infiltrating lymphocytes (TILs) were assayed for survival after withdrawal from exogenous IL-2. The activity and specificity of retrovirally transduced TILs were assessed using tumor coculture assays.
  
  
  RESULTS
  Human T cells transduced with the IL-15 HSV-TK vector exhibited thymidine uptake in the absence of exogenous cytokine support and survived in culture for up to 80 d without IL-2. IL-15 HSV-TK-transduced T cells were efficiently killed by ganciclovir at concentrations as low as 0.1 μM. TILs transduced with the IL-15 HSV-TK vector retained specific recognition of HLA-A2+, MART1+ melanomas, even after withdrawal of IL-2.
  
  
  CONCLUSIONS
  Human T lymphocytes genetically modified with the IL-15 HSV-TK retroviral vector retained the ability to recognize tumor antigen while gaining the ability to secrete IL-15 and prolong their own survival. IL-15 HSV-TK-transduced T cells expressed HSV-TK and could be efficiently eliminated by ganciclovir.
authors.affiliation: Division of Surgical Oncology, Department of General Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California 90404, USA. caryhsu@mednet.ucla.edu
authors.forename: Cary
authors.initials: C
authors.lastname: Hsu
authors.forename: John D
authors.initials: JD
authors.lastname: Abad
authors.forename: Richard A
authors.initials: RA
authors.lastname: Morgan
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000628:therapy; D045744:Cell Line, Tumor; D015870:Gene Expression / Q000276:immunology; D005818:Genetic Engineering / Q000379:methods*; D006801:Humans; D016219:Immunotherapy, Adoptive / Q000379:methods*; D019409:Interleukin-15 / Q000235:genetics*; D007376:Interleukin-2 / Q000494:pharmacology; D007938:Leukemia / Q000628:therapy; D008545:Melanoma / Q000628:therapy; D051379:Mice; D041681:NIH 3T3 Cells; D012190:Retroviridae / Q000235:genetics; D018139:Simplexvirus / Q000235:genetics*; D012878:Skin Neoplasms / Q000628:therapy; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology*; D013937:Thymidine Kinase / Q000235:genetics*; D014161:Transduction, Genetic; D019076:Transgenes / Q000235:genetics
chemical_list: C569274:IL15 protein, human; D019409:Interleukin-15; D007376:Interleukin-2; D013937:Thymidine Kinase
keywords: Cancer immunotherapy; Cytokine; Gene therapy; Human; Retroviral vector; Suicide gene; T cells