Generation of V α13/β21+T cell specific target CML cells by TCR gene transfer

Adoptive immunotherapy with antigen-specific T cells can be effective for treating melanoma and chronic myeloid leukemia (CML). However, to obtain sufficient antigen-specific T cells for treatment, the T cells have to be cultured for several weeks in vitro, but in vitro T cell expansion is difficult to control. Alternatively, the transfer of T cell receptors (TCRs) with defined antigen specificity into recipient T cells may be a simple solution for generating antigen-specific T cells. The objective of this study was to identify CML-associated, antigen-specific TCR genes and generate CML-associated, antigen-specific T cells with T cell receptor (TCR) gene transfer. Our previous study has screened an oligoclonal V beta 21 with a different oligoclonal V alpha partner in peripheral blood mononuclear cells (PBMCs) derived from patients with CML. In this study, oligoclonally expanded TCR a genes, which pair with TCR V beta 21, were cloned into the pIRES eukaryotic expression vector (TCR V alpha-IRES-V beta 21). Next, two recombinant plasmids, TCR V alpha 13-IRES-V beta 21 and TCR V alpha 18-IRES-V beta 21, were successfully transferred into T cells, and the TCR gene-modified T cells acquired CML-specific cytotoxicity with the best cytotoxic effects for HLA-A11(+) K562 cells observed for the TCR V alpha 13/V beta 21 gene redirected T cells. In summary, our data confirmed TCRV alpha 13/V beta 21 as a CML-associated, antigen-specific TCR. This study provided new evidence that genetically engineered antigen-specific TCR may become a druggable approach for gene therapy of CML.