WT1 and leukemia: In fact, a high-avidity TCR, S117A-TCR-transduced CD4+ T cells had a higher frequency of granzyme B/perforin-double positive cells and showed more potent cytotoxicity against WT1-expressing and HLA-DPB1*05:01-positive leukemia cells, compared to wt-TCR-transduced CD4+ T cells.