CD123 CAR T cells exhibit antileukemic effects in vivo. Mice were sublethally irradiated with 300 cGy from a ¹³⁷Cs γ-irradiator 24 hours prior to intravenous transplantation of 0.5 × 10⁶ KG1a-GFP-firefly luciferase cells. Five days later, mice received a single intravenous injection of 5.0 × 10⁶ CAR⁺ T cells. (A) Flow cytometric analysis of CAR-expressing T cells prior to use in vivo. Percentage of cells in each quadrant is indicated. (B) Bioluminescent imaging prior to T-cell treatment (day 4), on day 12, and on day 33 following KG1a-GFP-firefly luciferase transplantation. (C) Bioluminescent signal for each treatment group over time. Dotted line represents day of T-cell treatment. Data represent mean values of each group ± SD. Results represent pooled data from 2 separate experiments. PBS n = 3; CD19R, 26292, 32716 n = 6. (D) Representative flow cytometric analysis of peripheral blood 32 days after leukemia transplant. Percentage of viable human CD45⁺GFP⁺ KG1a cells is indicated. (E) Summary of leukemic cell engraftment in mouse peripheral blood 32 days after leukemia transplant. The percentage of viable human CD45⁺GFP⁺ KG1a cells is indicated. Each symbol indicates 1 mouse; bars represent mean values, and mean values for each group are indicated. (F) Kaplan-Meier analysis of survival for each group (PBS n = 3, CD19R n = 4, CD123-specific n = 10). Log-rank (Mantel-Cox) tests were used to perform statistical analyses of survival between groups. *P < .05.