Different kinetic patterns of BCR-ABL transcript levels in imatinib-treated chronic myeloid leukemia patients after achieving complete cytogenetic response

Summary Bone marrow BCR‐ABL transcript levels were monitored serially by real‐time quantitative PCR in 46 imatinib‐treated chronic myeloid leukemia patients after achieving complete cytogenetic response (CCyR) for a median of 42 months (range: 9–53). Of 41 patients in continuous CCyR, 32 and nine could achieve a ≥3‐log (MMoR group) or 2‐ to 3‐log reduction (non‐MMoR group), respectively. The MMoR group had a significantly lower recurrence rate of Ph+ metaphase than the non‐MMoR group (6/32 vs. 7/9, P = 0.002), which was not significantly different between patients first achieving CCyR within or after 12 months of imatinib treatment (7/27 vs. 6/14, P = 0.086). Five patients suffered cytogenetic or hematological relapse. For all 46 patients, a >2‐log reduction but not time when CCyR was first achieved was related to a lower relapse rate (1/42 vs. 4/4, P