PB1807: OUTCOME OF CORE BINDING FACTOR ACUTE MYELOID LEUKEMIA IN CHILDREN AND ADOLESCENTS: A SINGLE CENTER EXPERIENCE

Abstract

Background: Core binding factor acute myeloid leukemia (CBF-AML) is a subgroup of AML, mainly defined by two gene rearrangements affecting CBF;t (8; 21)/RUNX1-RUNX1T1 and inv (16)/CBFB-MYH11. CBF-AML is considered as a favorable cytogenetic group. However, one-third of these patients relapse succeeding treatment. Aims: The main of this study is to evaluate the clinical characteristics and the outcome of this group of patients in our center. Methods: This retrospective study included all CBF-AML diagnosed between 2002 and 2020 in the hematology department of the University Hospital of Sousse. Patients were aged 20 years or less. The diagnosis was confirmed according to the WHO classification of hematological malignancies based on cytology and immune-phenotyping. An initial karyotype during diagnosis was performed in all the cases to classify the cases according to the prognostic MRC classification. Patients were treated by the standard chemotherapy regimen. Promyelocytic leukemia and secondary leukemia were excluded. Statistical analysis was performed using the Kaplan Meier method. Results: Among the 66 children and adolescents diagnosed with AML 15 had CBF AML (23%). 60% were male. The median age was 9 years (3-16). WBC at diagnosis was<4000 in 5 cases, 4000-10000 in 2 cases, between 10000-50000 in 7 cases, and >50000 in 1 case. Disseminated intravascular coagulation was noted in 2 cases. Twelve patients had t(8,21) and 3 patients had inv(16). 75% achieved complete remission after induction. 2 patients had a refractory disease (12,5%). Treatment-related mortality was 12,5% and meantime to relapse was 6,2 months in 5 patients (45%). Three patients responded to salvage chemotherapy (60%) and 2 died (40%). Hematopoietic stem cell transplantation (HSCT) was performed in only 2 patients. For the 3 others, HSCT was not feasible because of the absence of compatible matched related donors. The 5-year overall survival and relapse-free survivals were 55,7% and 58,3% respectively. Summary/Conclusion: Compared to the literature, the frequency of CBF-AML and epidemiological features were very similar. Furthermore, the majority had t (8, 21) in karyotype. Complete remission rate was slightly lower in our study (73% vs 85-96%), Treatment-related mortality was higher (12% vs 3-10%) which may be explained by the absence of protective isolation in the earlier years of the study. Regrettably, PFS was inferior to data from the literature (70-80%). The early use of stem cell transplants could improve our results.