Fig 2: C10 TRuC T cells are fratricide resistant and exhibit potent and durable antitumor efficacy in vivo. (A) Experimental design of fratricide assay, in which CTV-labelled NT T cells are challenged with TRuC T cells at E:T of 9:1, 3:1, 1:1 and 1:3. (B) CD70 expression percentage was measured by flow cytometry for resting and anti-CD3/CD28 bead-activated CD4+ and CD8+ T cells. Columns depict the mean ± SEM. (C) Percentage of resting or activated CTV-labelled NT T cells killed when challenged with different E:T ratios of NT, C10 TRuC T cells and fratricidal 15F6 TRuC T cells for 48 hours, as evaluated by flow cytometry, mirroring the fold-change in CTV+ cells depicted in Supplementary Figure 3A . Each point represents the mean ± SEM. (B, C) report data from n=3 donors, all experiments performed in duplicate or triplicate, and data pooled. Quantification of the tumor burden in mouse models was performed following challenge with NT, 15F6 TRuC or C10 TRuC T cells. (D) The tumor burden of systemically administered MOLM-13-Luc (AML) cells following treatment was followed by means of bioluminescence. Changes in subcutaneous 786-O tumor volumes were measured using calipers, both following NT or TRuC T-cell treatment (E) and after re-challenging the opposing flank of the treated mouse with 786-O (RCC) cells (F). In vivo data in (D–F) were obtained using T cells from a single donor and studies of 5 mice per group. In vitro treatment groups were compared via one-way ANOVA, followed by Dunnett’s multiple comparison test; in vivo treatment groups were compared using a two-way repeated-measures ANOVA, followed by the Bonferroni post hoc test; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. AML, acute myeloid leukemia; ANOVA, analysis of the variance; CTV, CellTrace Violet; E:T, effector:target; NT, non-transduced; SEM, standard error of the mean; TRuC, T-cell receptor fusion construct.