Reduced-intensity allogeneic hematopoietic stem cell transplantation combined with imatinib has comparable event-free survival and overall survival to long-term imatinib treatment in young patients with chronic myeloid leukemia

The relative merits of reduced intensity hematopoietic stem cell transplantation (RIST) for chronic myeloid leukemia (CML) in the first chronic phase (CP) in imatinib era have not been evaluated. The study was designed to compare the outcomes of combination therapy of RIST plus imatinib (RIST + IM) vs. imatinib (IM) alone for young patients with early CP (ECP) and late CP (LCP). Of the patients, 130 were non-randomly assigned to treatment with IM alone (n = 88) or RIST + IM (n = 42). The 10-year overall survival (OS) and event-free survival (EFS) were comparable between RIST + IM and IM groups. LCP, high Sokal score, and no complete cytogenetic response at 3 months were adverse prognostic factors for survival, but only the time from diagnosis to IM was an independent predictor after multivariate analysis. For ECP, IM was similar to RIST + IM, with 10-year EFS rates of 77.2 vs. 81.6% (p = 0.876) and OS rates of 93.8 vs. 87.9% (p = 0.102), respectively. For LCP, both treatments resulted in similar survival, but more patients in the imatinib group experienced events (10-year EFS 40.8 vs. 66.7%, p = 0.047). The patients with higher EBMT risk scores had an inferior survival than those with lower scores (69.2 vs. 92.9%, p = 0.04). We concluded that RIST + IM was comparable to IM in terms of OS and EFS. However, RIST + IM was more affordable than IM alone in a 10-year scale. Thus, RIST + IM could be considered as an alternative treatment option, especially when the patients have low EBMT risk scores and demand a definite cure for CML.