Characterization of human T lymphocytes engineered to express interleukin-15 and herpes simplex virus-thymidine kinase.
INTRODUCTION
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.
['Hsu|Cary|C|', 'Abad|John D|JD|', 'Morgan|Richard A|RA|']
D000818:Animals D001327:Autoimmune Diseases D045744:Cell Line, Tumor D015870:Gene Expression D005818:Genetic Engineering D006801:Humans D016219:Immunotherapy, Adoptive D019409:Interleukin-15 D007376:Interleukin-2 D007938:Leukemia D008545:Melanoma D051379:Mice D041681:NIH 3T3 Cells D012190:Retroviridae D018139:Simplexvirus D012878:Skin Neoplasms D013601:T-Lymphocytes D013937:Thymidine Kinase D014161:Transduction, Genetic D019076:Transgenes
Human T cells Gene therapy Retroviral vector Suicide gene Cytokine Cancer immunotherapy