CD1a CARTs fully abolish the progression of primary CD1a⁺ coT-ALL blasts in a PDX setting. (A) Scheme of the PDX model. NSG mice (n = 5–6/group) were IV injected with 1 × 10⁶ primary coT-ALL cells followed 3 days after by a single IV injection of 1 × 10⁶ MOCK or CD1a CARTs. Tumor burden was monitored according to FACS every other week by bleeding and BM aspirate after 6 and 9 weeks. Frequency of leukemic mice and levels of leukemia in BM (B) and PB (C) 6 and 9 weeks after infusion of CARTs. The left panels show representative FACS plots. Primary CD1a⁺ T-ALL blasts are shown in blue, effector T cells are shown in red, and mouse cells are shown in black. (D) Nine-week OS of coT-ALL primografts receiving either CD1a CARTs or MOCK T cells. (E) Effector T-cell persistence over time in PB (week 2 toward week 9) and BM (weeks 6 and 9). Each dot represents an independent mouse. *P < .05, **P < .01, ***P < .001, Malcolm-Cox test.