TIM-3 Up-regulation Is Associated With Altered Cytotoxic Function of Allogeneic Vγ9Vδ2 T Cells in Urinary Bladder Cancer

Background/Aim: γδ T cells, particularly the Vγ9Vδ2 subset, can recognize and directly kill cancer cells. γδ T-cell infusion can be autologous or allogeneic, but cancer cells employ various defense mechanisms against immune attack. This study evaluated the in vitro cytotoxic activity of patient-derived γδ T cells against urinary bladder cancer (UBC) cells and investigated TIM-3 expression and the effects of TIM-3 blockade on γδ T-cell cytotoxicity. Materials and Methods: Peripheral blood mononuclear cells (PBMCs) from UBC patients and healthy volunteers (HVs) were expanded ex vivo for 11 days and assessed for Vγ9Vδ2 T-cell expansion, differentiation, and cytotoxicity against cancer cells in vitro. Surface expression of checkpoint molecules on γδ T cells was also analyzed. Results: Ex vivo-expanded γδ T cells from UBC patients expanded and differentiated into Vγ9Vδ2 T cells as efficiently as those from HVs but showed weaker cytotoxicity against UBC cells. TIM-3 was consistently and highly expressed throughout γδ T-cell expansion. Blocking TIM-3 signaling significantly increased the cytotoxicity of allogeneic HV-derived γδ T cells against UBC cells in vitro, although a similar effect was not observed in a small number of patient-derived samples tested. Conclusion: Ex vivo-expanded autologous γδ T cells from UBC patients expanded and differentiated normally but showed reduced cytotoxicity. Targeting TIM-3 enhanced the cytotoxicity of allogeneic Vγ9Vδ2 T cells in vitro, suggesting a promising strategy for improving allogeneic γδ T-cell-based immunotherapy for UBC; whether TIM-3 blockade similarly benefits patient-derived γδ T cells remains to be determined.