FIG. 5.

Therapeutic efficacy and specificity of a single injection of RNA CAR⁺ T cells in Nalm-6 xenograft model. (A) NSG mice were injected with 10⁶ Nalm-6 transduced to stably express firefly luciferase, as in Supplementary Fig. S1, followed by a single tail-vein injection of 2.5×10⁷ T cells electroporated with CD19-BBz or meso-BBz mRNA 7 days later (arrow). Animals were imaged at the indicated time points post injection, with total photon flux±SE indicated on the y-axis; 5×10⁵ p/sec/cm²/sr represents mice with no luciferase-containing cells. *p<0.01. (B) Photon-density heat maps of firefly luciferase-positive leukemia in representative mice at day 5 (2 days before treatment) and day 8 (24 hr post CAR⁺ PBLs). Mice start with an equal burden of leukemia, but CD19-directed CAR⁺ PBLs reduce disease burden by 2 logs (but do not eliminate it) as measured by photon density. (C) Survival of those mice treated with CD19-BBz RNA CAR⁺ T cells is significantly prolonged compared with that of saline controls and meso-BBz CAR T cell groups. p<0.01 by log rank analysis. (D) Survival with RNA CAR CTLs compares favorably with that with lentiviral generated CAR CTLs in the same model, although no long-term survivors are noted with a single infusion of RNA CAR CTLs, consistent with our observation that single injection does not entirely eliminate disease (n=12, summation of two independent experiments).