Objective: To investigate the value of flow cytometry (FCM) detection in prognostic evaluation of minimal residual disease (MRD) of acute myeloid leukemia (AML) patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT).
Methods: Eighty-two cases of AML (except M3) after allo-HSCT who accord to enrolled condition (no MRD positive after allo-HSCT confirmed by regular flow cytometry detection and followed-up for 2 years) from April 2012 to September 2016 in our department were selected. Among 82 cases males were 50 and females were 32 with average age of 27.27 (2-57) years old. According to FAB classification, 2 cases were classified as M0/M1, 51 cases as M2, 24 cases as M4/M5 and 5 cases as M6. The antibody panels were selected accordingly to the initial leukemia associated immunophentype(LAIP) of patients.
Results: Twenty patients (24.39%) were identified as MRD+ (0.10%-4.91%, mean 1.64%) in 82 AML patients after allo-HSCT (all the patients were in complete remission phase based on bone marrow morphology). During follow-up, 16 cases relapsed (relapse rate 80%)in 20 MRD+ cases, including 1 case with extramedullary relapse; 4 out of 62 MRD- cases relapsed (relapse rate 6.45%)in bone marrow, and 2 cases extramedullary relapsed. The average survival time of leukemia- free survival (LFS) in group MRD+ was 15.19 ± 3.99 months, median LFS was 10± 3.84 months. The average LFS time was 53.50 ± 1.69 months in MRD- group (P<0.001). The average overall survival (OS) of the MRD+ group was 22.52 ± 5.72 months, the median OS was 18 ± 3.27 months; the average OS time was 42.86 ± 2.83 months in MRD- group(P=0.008).
Conclusion: For the patients with morphologically complete remission after allo-SCT, the FCM regular monitoring of bone marrow MRD closely relates with its relapse rate, LFS and OS. Compared with the MRD- group, the relapse rate of MRD+ group is significantly increases, and the LFS and OS significantly decreases.