Objective: To explore dynamic status of bcr-abl transcript levels in chronic myeloid leukemia (CML) patients after allogeneic HSCT and to define low relapse patients who may not require further therapeutic intervention.

Methods: One hundred and forty-nine CML cases received allo-HSCT at our Institute between Nov. 2004 and Nov. 2006. Bcr-abl transcripts levels were monitored from bone marrow samples by Q-RT-PCR in all cases pre-HSCT and at 1, 2, 3, 4, 5, 6 months post HSCT. The median value of bcr-abl at these time points were calculated and compared by Mann-Whitney U test. The relapse rate, overall survival (OS) and incidence of graft versus host disease (GVHD) were calculated by Kaplan-Meier curve.

Results: All cases engrafted. 2-year OS rate was 86.0% (CI: 82.9% -89.1%), 2-year accumulated hematological relapse rate (RI) was 3.5% (CI: 1.7% -5.3%). 102 cases were not received any further intervention and none of them relapsed. The median value of bcr-abl transcripts was 25.800% (CI: 0.067% - 96.100%) pre-HSCT and 0.025% (CI: 0 - 3.583%) at +30 d, 0.011% (CI: 0-0.425%) at +60 d, 0.002% (CI: 0 - 0.610%) at +90 d, 0 (CI: 0 - 0.056%) at +120 d post HSCT. The bcr-abl mRNA levels decreased to undetectable level at +3 m, +4 m, and +5 m in recipients from HLA-mismatched related donor, identical sibling donor and unrelated donor respectively.

Conclusions: Serial monitoring of bcr-abl transcript levels by real-time quantitative PCR after allo-HSCT is helpful for screening CML patients with low risk of relapse.