A multiplexed edited CART targeting CD7 is highly effective in improving survival in PDX of pediatric T-ALL. (A) CD7 expression on 6 unique PDX of pediatric T-ALL measured by flow cytometry are shown. Blue histograms represent CD7 expression on PDXs, and red histograms represent isotype controls. (B) Schematic of PDX T-ALL animal model studies. (C) 7CAR8 is highly effective in improving disease burden as measured by the surrogate total mean flux over time and in improving survival. A representative PDX sample of ETP T-ALL (ETP 5) was modified to express luciferase and was treated with 7CAR8. Total mean flux was significantly lower in the 7CAR8-treated arm than the UTD T-cell arm. Representative images of mice treated with UTD and 7CAR8 at day 0 and day 25 are also shown. 7CAR8 improved survival in treated mice with ETP5 (n = 3 mice per arm). (D) 7CAR8 improved survival in 5 unique PDXs. Programmed cell death protein (PD1) knock-out (KO) CART were compared with those without PD1 edit (WT) in a subset of experiments. PD1 KO CART were noninferior to PD1 WT CART in most samples. In the PDX ALL8, mice treated with the PD1 KO CART tended to survive longer than those treated with the wild type. Mice treated with either 1 × 10⁶ or 5 × 10⁶ UTD cells displayed no differences in survival.