Several groups have shown that that the BCR-ABL1 transcript level measured at 3 or 6 months after starting treatment with tyrosine kinase inhibitors strongly predicts clinical outcomes for patients with chronic myeloid leukemia. In this work, we asked whether the prognostic value of the 3-month transcript level could be improved by combining the 3- and 6-month results. We classified patients treated with imatinib and patients treated with dasatinib according to their transcript levels at 3 months and 6 months. The patients who met the 3-month landmark but failed the 6-month one had outcomes identical to those of patients who met both landmarks, whereas the patients who failed the first landmark but met the second one had prognoses similar to those who failed both landmarks. In summary, early intervention strategies can be based robustly just on the transcript level at 3 months. This trial was registered at www.clinicaltrials.gov as # NCT01460693.