Anti-CCR9 CAR has potent anti-leukemic activity in PDX models of T-ALL. (A) Flow diagram of PDX model 1, n = 4 per group. (B) Flow cytometry of CCR9 expression in blasts of PDX model 1. (C) Serial bleeds of mice, percent tumor of total CD45⁺cells. (D) Survival of mice in PDX model 1. (E) Spleen mass at necropsy in PDX model 1. (F) Tumor in spleen, percentage of total CD45⁺ cells. (G) Tumor in marrow, percentage of total CD45⁺ cells. (H) Flow diagram of PDX model 2, n = 5 (NT), n = 3 (CAR19), and n = 5 (CARCCR9). (I) Flow cytometry of CCR9 expression in blasts of PDX model 2. (J) Serial bleeds of mice in PDX model 2, percent tumor of total CD45⁺cells. (K) Survival of mice in PDX model 2. (L) Spleen mass at necropsy in PDX model 2. (M) Tumor in spleen in PDX model 2, percentage of total CD45⁺ cells. (N) T cells in spleen in PDX model 2, percentage of total CD45⁺ cells. (O) T cells and tumor in marrow of CARCCR9 recipients in PDX model 2, percentage of total CD45⁺ cells. *P < .05, **P < .01, ****P < .0001. NR, not reported; ns, not significant; OS, overall survival; PB, peripheral blood.