PROGNOSTIC SIGNIFICANCE OF MINIMAL RESIDUAL DISEASE IN CHILDREN WITH ACUTE MYELOID LEUKAEMIA
Objective. Estimation of the prognostic role of the minimal residual disease (MRD) determined by multicolour flow-cytometry in the bone marrow of the pediatric patients with acute myeloid leukemia (AML) treated according to the AML-MM-2006 and AML-MM-2014 protocols at the end of the induction therapy.
Materials and methods. The study included 43 patients among them 29 (67.4%) boys and 14 (32.6%) girls. The median age was 8.07 years. The residual tumor cells were determined by 8-color flow cytofluorometry on a Navios device (Beckman Coulter, USA) using the reagents of this company.
Results. Determination of the leukemia-associated immunophenotype at the time of diagnosis and of MRD presence was successful in 91.5% of patients. 23.2% of patients had the MRD level in the bone marrow less than 0.1% at the end of the induction therapy (28—43 days of therapy). The remaining patients (76.8%) had the MRD level 0.1% or higher. Among the patients with MRD<0.1%, the M2 morphology of the blast cells and t(8; 21) occurred more often than in the group of patients with MRD³0.1%. Patients with MRD<0.1% were older 10 years in 80% of cases. 5-year event-free survival among the patients with MRD<0.1% was 100% at the end of the induction therapy being statistically significantly (p=0.0491) higher when compared with the same parameter in the group of patients with MRD³0.1% — 55%±11%.
Conclusion. Our results show that MRD detected by flow-cytometry after the induction therapy predicts negative outcomes in patients with childhood AML and can help stratifying the post-remission treatment.