Fig. 2
h1218-CART19 recognize and kill malignant B cells carrying FMC63-resistant CD19 mutations. A Schematic representation of B cell leukemia cells with point mutations in the membrane-distal CD19 domain (CD19R163L or CD19L174V) as clinically identified post FMC63-CART19 treatment. B CD19 expression levels in Nalm6-CD19 KO, Nalm6 (wild type), Nalm6-CD19L174V (left) and Nalm6-CD19R163L (right) cell lines as measured by flow cytometry. C CART19 cytotoxicity against Nalm6-CD19L174V and Nalm6-CD19R163L at various effector to target (E:T) ratios (n = 3 independent donors) (luciferase assay). D IL-2 and TNF cytokine release measured by ELISA 24 h after CART19 and cancer cell co-culture at an E:T ratio of 5:1 (n = 2 donors). All values determined to be negative by comparison with the standard curve are shown as zero. E (Left) Schematic of the xenograft NSG mouse model: 1 × 106 luciferase + Nalm6-CD19L174V cells and 0.75 × 106 UTD, FMC63-CART19, or h1218-CART19 cells were intravenous injected with a 5-day interval. (Right) Tumor burden of engrafted mice treated with UTD (n = 5), FMC63-CART19 (n = 5), or h1218-CART19 (n = 5) as measured by bioluminescence imaging. The bold lines represent the median luminescence of each group. F Overall survival in each treatment group (p = 0.0027). G Absolute cell counts of huCD45+ huCD3+ T cells in 100μL mouse blood on day 9. All bar graphs and cytotoxicity curves are presented as the mean ± SEM. Survival curves were compared using the log-rank (Mantel-Cox) test, and one-way ANOVA was performed with Tukey’s correction for multiple comparisons; **** p < 0.0001, *** p < 0.001, ** p < 0.01, and * p < 0.05. All bar graphs are presented as the mean ± SEM. All experiments were repeated at least twice