Among patients with CML-CP without T315I, major molecular response (MMR; BCR::ABL1 ≤ 0.1% on the International Scale [IS]) was achieved or maintained by 12 months in 44 of 91 evaluable patients (48%) (median response duration, >61 weeks), whereas 4 patients lost MMR (1 with MMR at baseline). This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.