Fig 1: Acetazolamide, tacrolimus, and LB‐100 impair the maintenance of KMT2A::AFF1+ B‐cell precursor acute lymphoblastic leukemia (BCP‐ALL). (A) Experimental design of the drug study to assess the effect of acetazolamide, tacrolimus, and LB‐100 in the maintenance of KMT2A::AFF1+ BCP‐ALL in NSG mice xenotransplanted with SEM cells. The treatment was initiated when 1% human cells were detected in the peripheral blood of NSG‐SEM mice. (B) Human cell contribution in the peripheral blood over the course of the 12‐day treatment. (C) Absolute number of SEM cells in the bone marrow of NSG mice (vehicle and drug) at Day 12. (D) Experimental design of the monotherapy drug study to assess the effect of acetazolamide on the survival of NSG mice xenotransplanted with cells derived from an infant KMT2A::AFF1+ BCP‐ALL patient. (E) Reverse transcription quantitative polymerase chain reaction (RT‐qPCR) of miR‐128a, miR‐130b, miR‐194, miR‐99b, and miR‐125a‐5p in leukemic cells from the infant KMT2A::AFF1+ BCP‐ALL patients used in (D). (F) Correlation of CA5B and miR‐194 expression in leukemic cell lines and the primary sample used in (D). (G) Human cell contribution in the peripheral blood 5 days after the end of the treatment. (H) Survival curve of NSG mice xenotransplanted with cells derived from an infant KMT2A::AFF1+ BCP‐ALL patient: vehicle‐ and acetazolamide‐treated. (I) Experimental design of combination therapy to assess the effect of acetazolamide alongside an induction therapy on the survival of NRG‐S PDX mice xenotransplanted with cells derived from an infant KMT2A::AFF1+ BCP‐ALL patient. (J) CA5B, PPP3CA, and PPP2R5C expression in an infant KMT2A::AFF1+ BCP‐ALL patient (Utrecht). (K) Total body luminescence signal (BLI) over time during and after the treatment for VXLC (n = 6), VXLC + acetazolamide (n = 6), and VXLC + acetazolamide + maintenance (n = 5) groups. Data are presented as mean ± SEM and compared using a Welch's t‐test. (L) Survival curve of VXLC‐, VXLC + acetazolamide‐, and VXLC + acetazolamide + maintenance‐treated groups. Survival differences were assessed using a Gehan–Breslow–Wilcoxon test. Data are presented as mean ± 95% CI. P < 0.05 (*), P < 0.01 (**), P < 0.001 (***), and P < 0.0001 (****).