PB1812: CORE BINDING FACTOR ACUTE MYELOID LEUKEMIA IN PEDIATRIC POPULATION: THE RESULTS OF A MONOCENTRIC EXPERIENCE

Abstract

Background: The core binding factor acute myeloid leukemia (CBF-AML) is characterized by t(8;21) and inv(16)(p13q22)/t(16;16)(p13;q22) cytogenetic abnormalities. It is associated with a good prognosis. Aims: In this study, we aimed to assess the treatment outcome of the pediatric CBF- AML in comparison with non CBF-AML treated in our center. Methods: We retrospectively reviewed data of patients under the age of 20 diagnosed with de novo AML in our center during january 2005 and december 2020. The treatment protocol includes: a course of induction (Cytarabine 200mg/m2/day associated with Daunorubicine (DNR) 60 mg/m2/day or Novantrone 12mg/m2/day). If a complete remission (CR) is achieved the chemotherapy is followed by: a cure of ADE (Cytarabin, DNR, Etoposide) associated with 2 cures of high dose of Cytarabine (12g/m2) before 2011 and a cure of ADE associated with 3 cures of high dose of cytarabine (18g/m2) after January 2011. Allogeneic stem cell transplantation (ASCT) from matched sibling donors was limited to patients who are in CR1, having an HLA-identical family donor before January 2011 and for patients who are in CR2 after January 2011. Endpoints were complete remission (CR), overall survival(OS), event free survival (EFS) and relapse rate. Survival statistical analysis performed with Kaplan Meyer method. Results: A total of 52 patients were included, of whom 16 (30%) presented CBF genes. The median age was 10years. The median white blood cells count at diagnostic was 28G/L. Distribution according to the FAB classification was as followed: 1(6%)M1, 8(50%) M2, 6(38%) M4 and 1(6%) M6.the most frequent subgroup was M2 (vs M1 in non CMF-AML, p=0.001). Cytogenetic analysis showed the Inv 16 (p13;q22) in 3 cases (18%) and t(8;21) (q22;q22) were observed in 11 cases (68%). Two patients had both CBFB–MYH11and AML-ETO rearrangement. Six cases (38%) had additional cytogenetic abnormalities. The correlation between cases with and without additional cytogenetic abnormalities did not conclude to any significent difference in terms of CR rate, OS and EFS. We observed a comparatively higher CR rate (87% vs 51% p=0.018) and also a better OS rate (83% vs 35%, p=0.02) at 5 years between CBF-AML and non CBF-AML. In contrast, there was no statisticly significent difference in terms of the EFS (67%vs 62%, p=0.4) and the relapse rate (31% vs 43%, p=0.3) between the 2 groups. Relapse occurred in 5 cases (31%) at a median of 13 months. A second remission was obtained in 2/5 patients. ASCT was performed in only 4 cases (3 after RC1 and 1 after relapse). Summary/Conclusion: The frequency of core binding AML in our study is higher than what has been reported in the literature (30 vs 15%) with predominance of The cytogenetic t(8,21) (68%). The additional cytogenetic abnormalities has no prognostic value. Long term survival in our series compared favorably with results reported by cooperative groups. It can be concluded that ASCT in CR1 for pediatric CBF-AML is no longer indicated.