Reduction in fusion transcript ratio by CBF subset and treatment arm. A total of 176 (90 CBFα and 86 CBFβ; 89 arm A and 87 arm B), 176 (91 CBFα and 85 CBFβ; 88 arm A and 88 arm B), and 160 (79 CBFα and 81 CBFβ; 80 arm A and 80 arm B) patients in first CR after having received the planned chemotherapy and no SCT were tested for MRD response at MRD1, MRD2, and MRD3 time point, respectively. Overall, 86 of 176 (50%), 124 of 176 (70.5%), and 130 of 160 (81%) achieved a 3-log MRD reduction at MRD1, MRD2, and MRD3 time point, respectively. (A) Median ratio was 0.20% vs 0.145%, 0.055% vs 0.05%, and 0.020% vs 0.025% at the MRD1, MRD2, and MRD3 time point in the RUNX1-RUNX1T1 vs CBFB-MYH11 subset, respectively (P = .71, 0.19, and 0.17, respectively, Mann-Whitney U test). The rate of patients who reached the 0.1% level at MRD2 was 60% (57% and 62% in the RUNX1-RUNX1T1 and CBFB-MYH11 subset, respectively; P = .54, Fisher’s exact test). (B) Median ratio was 0.10% vs 0.26%, 0.023% vs 0.10%, and 0.013% vs 0.030% at the MRD1, MRD2, and MRD3 time point in arm A and arm B patients, respectively (P = .006, 0.0002, and 0.013, respectively, Mann-Whitney U test).