NSG mice were injected with 1e6 firefly-luciferase labeled tumor cells including an MLLr B-ALL patient-derived xenograft, the parental SEM MLLr B-ALL cell line, and a CD19-knockdown CRISPRi SEM cell line (CD19- MLLr B-ALL). After confirming engraftment, mice were treated with a single dose of 5e6 CAR T cells (1:1 CD8/CD4 mixture) on day 10 (MLLr B-ALL PDX) or day 3 (parental and CD19- SEM MLLr B-ALL). Tumor burden was assessed weekly for five weeks via bioluminescent imaging (BLI), then mice were followed for survival. Survival curves and tumor burden via BLI for mice that received (a) MLLr B-ALL PDX and were treated on day 10 with different CAR T cells (n=6 mice per arm); (b) SEM B-ALL cells, treated on day 3 with different CAR T cells (n=6/arm); (c) CD19-negative SEM B-ALL cells, treated on day 3 with different CAR T cells (n=6/arm). p-values were computed using the log-rank test comparing different CAR constructs to Empty CAR controls, except for 6c where CD72 CAR is compared directly to CD19 CAR. See also Supplementary Fig. S8.