Imatinib Mesylate Is Superior to Allogeneic Hematopoietic Stem Cell Transplantation As the First-Line Therapy for Patients with Chronic Myeloid Leukemia in the Early Chronic Phase

The relative merits of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for chronic myelogenous leukemia (CML) in the first chronic phase (CP) in the imatinib era have not previously been evaluated. This prospective cohort study was designed to compare the medical outcomes and quality of life (QOL), with imatinib versus allo-HSCT from an HLA-matched sibling donor for CML in the first CP including the early CP (ECP; a CML duration < 12 months) and the late CP (LCP; a CML duration ' 12 months).

From April 2001 to April 2010, patients treated consecutively at the Peking University People's Hospital, Peking University Institute of Hematology were nonrandomly assigned to treatment with imatinib or allo-HSCT according to whether the patient had an HLA-matched sibling donor; those with an HLA-identical sibling donor were assigned to the allo-HSCT group, and the others were assigned to the imatinib group. QOL of surviving patients still in the imatinib and allo-HSCT groups was measured by the Medical Outcomes Survey Short Form 36 (MOS SF-36) at the end of the study evaluation period in April 2011.

In total, 463 patients were recruited, 209 patients were assigned to the allo-HSCT group and 254 patients were assigned to the imatinib group, respectively.Based on a ten-year follow-up period, a multivariate analysis revealed that allo-HSCT was an independent adverse prognostic factor for event-free survival (EFS; estimated HR=2.4, P=0.002 and estimated HR=0.31, P<0.001) and overall survival (OS; estimated HR=6.9, P<0.001 and estimated HR=26.2, P=0.001) for the total population (n=463) and the patients in the ECP (n=348), and an independent favorable predictor of progression-free survival (PFS; estimated HR=3.2, P=0.020) for the total population. Imatinib was superior to allo-HSCT, with six-year EFS and OS rates of 83.6% vs. 76.6% (P=0.041) and 96.4% vs. 82.0% (P<0.001), respectively, for the entire cohort and 90.3% vs. 74.3% (P=0.001) and 99.4% vs. 80.2% (P<0.001), respectively, for the patients in the ECP, despite six-year PFS rates of 90.7% vs. 96.6% (P=0.014), respectively, for the entire cohort and 95.9% vs. 97.3% (P=0.303) respectively, for the patients in the ECP. Both treatments resulted in similar EFS and OS rates in those in the LCP (n=115), with a probability of six-year EFS rate of approximately 80% and six-year OS rate of more than 90%. More LCP patients in the imatinib group experienced relapse compared with those in the allo-HSCT group, with six-year PFS rates of 86.0% vs. 100% (P=0.035), respectively. There was no correlation between the EBMT risk score and EFS, OS or PFS in the patients receiving allo-HSCT.

Among the 392 surviving patients who were invited to participate in the QOL survey, 295 (75.3%) patients including 180 of 218 (82.6%) in the imatinib group and 115 of 174 (66.1%) in the allo-HSCT group, respectively, completed the questionnaires. A multivariate analysis revealed that there was no correlation between the treatment mode and the physical health for the total, ECP and LCP population, however, allo-HSCT was one of the independent factors associated with good mental health (estimated HR=0.5, P<0.001) in the ECP patients. The Physical Component Summary were comparable between the imatinib group and the allo-HSCT group, however, the Mental Component Summary of the patients experienced allo-HSCT were better than those receiving imatinib for the total (P=0.001), ECP (P=0.015) and LCP (P=0.010) population.

We concluded that imatinib confers significant survival advantages and a desirable QOL and is superior to allo-HSCT as the first-line therapy for patients with CML in the ECP.

All trials were registered with www.chictr.org as CHiCHTR-TNC-10000955.

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.