While immunotherapies such as anti-PD-1 therapy have provided an important treatment option for bladder cancer, the majority of patients do not respond to these regimens. This may reflect the distinct activation requirements of other immune T-cells besides CD8+ T-cells. In recent work, Dr. Oh and colleagues have identified cytotoxic (cancer cell-killing) CD4+ T-cells in human bladder cancer that are associated with immunotherapy responses. However, the regulation of cytotoxic CD4+ T-cells and how these mechanisms compare with CD8+ T-cells is not understood. Dr. Oh proposes to identify and validate surface receptors that enhance or inhibit the activity of cytotoxic CD4+ T cells in human bladder cancer, and the tumor antigens that are recognized specifically by these cells. He will also compare which of these regulatory mechanisms are unique to cytotoxic CD4+ T-cells relative to their CD8+ T-cell counterparts from the same patients. This work has the potential to increase both the proportion of bladder cancer patients who respond to immunotherapy as well as the quality of their response.