Low dose gemcitabine increases the cytotoxicity of human V?9V?2 T cells in bladder cancer cells in vitro and in an orthotopic xenograft model.
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ABSTRACT: Human ??T cell immunotherapy is well tolerated and has shown promising results in clinical trials; however, its antitumor efficacy is limited, including results in solid tumors. Ex-vivo expanded ??T cell stimulated by zoledronic acid (ZOL) activates the ??T cell subpopulation of so called V?9V?2 T cells. To improve the clinical outcomes of V?9V?2 T cell (abbreviated as ??T cell here) immunotherapy, we aimed to increase the cytotoxicity of ??T cells by focusing on two issues: recognition of tumor cells by ??T cells and the effector (??T cell)-to-target (tumor cell) (E/T) ratio. Ex vivo-expanded ??T cells showed potent cytotoxicity against urinary bladder cancer (UBC) cells in in vitro assays. Combination treatment with standard anticancer agents showed that low dose gemcitabine pretreatment significantly enhanced the cytotoxicity of ??T cells by upregulating the expression of MICA and MICB (MICA/B), which are tumor-associated antigens recognized by ??T cells. These effects were abrogated by small interfering RNA-mediated knockdown of MICA/B in UBC cells, suggesting that pre-exposing cancer cells to anticancer agents could be a promising strategy. A bladder instillation approach was used to increase the E/T ratio. The efficacy of ex vivo-expanded ??T cell immunotherapy was examined in an orthotopic xenograft model. In Vivo Imaging System analysis revealed the potent cytotoxicity of weekly intravesical administration of ??T cells, and weekly gemcitabine pretreatment enhanced the cytotoxicity of ??T cells in vivo. In conclusion, intravesical ??T cell immunotherapy and combination therapy with low dose gemcitabine may be a promising strategy in UBC.
SUBMITTER: Shimizu T
PROVIDER: S-EPMC5927545 | biostudies-literature | 2018
REPOSITORIES: biostudies-literature
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