Long-term follow-up of imatinib plus combination chemotherapy in patients with newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia

The effects of imatinib plus chemotherapy were assessed in 87 patients with newly diagnosed Philadelphia chromosome-positive (Ph⁺) acute lymphoblastic leukemia (ALL). Imatinib was administered continuously, starting from the eighth day of remission induction chemotherapy, then through five courses of consolidation or until allogeneic hematopoietic cell transplantation (HCT). Patients who were not transplanted were maintained on imatinib for 2 years. Eighty-two patients (94.3%) achieved complete remission (CR). Among these 82 CR patients, 40 experienced recurrence of leukemia. The 5-year relapse free survival (RFS) rate and overall survival (OS) rates were 39.0% and 33.4%, respectively. In total, 56 patients underwent allogeneic HCT in first CR. The 5-year cumulative incidence of relapse and OS rate of them were 59.1% and 52.6%, respectively. Six of seven patients who were maintained on imatinib after completion of consolidation relapsed and the median time of RFS was 40.7 months. In total patient, cumulative molecular CR rate was 88.5% and median time of molecular CR duration was 13 months. Initial imatinib dose intensity was significantly associated with median CR duration (P < 0.0001), and overall survival (P = 0.002). During the initial phase of treatment of patients with Ph⁺ ALL, it is important to maintain imatinib dose intensity.