Pb1824: impact of day 15 bone marrow aspiration on prediction of complete remission and relapse in acute myeloid leukemia

Background: Although all the progress made in hematology in the last decades, the treatment of acute myeloblastic leukemia (AML) is still disappointing with long term survival which does not extend 40%. Aims: The aim of our study is to assess the impact of early bone morrow blast (BMB) clearance in prediction of complete remission and relapse risk in acute myeloid leukemia Methods: We conducted a retrospective study including patients with AML treated with standard induction chemotherapy (3 days of idarubicine 12mg/m2 and 7days of cytarabine 200mg /m2) at the department of hematology at Aziza Othmena Hospital in Tunisia during 2020 - 2021. Results: Thirty four patients were included. The median age was 41 (range 17-57) and sex ratio was 1.5 (22M/12F). At the time of diagnosis, the median of white blood cells count was 57.8G/L (range 0.76-300G/L) and cytogenetic data were available for 91% of patients. According to cytogenetic stratification, our patients were classified as favorable in 29%, intermediate in 45.1% and unfavorable risk in 25.8% of cases. At the end of induction course, complete remission (CR) was achieved in 64% of patients. Induction related mortality was 8.8%. The most common cause of death was infection (66%). Bone morrow aspiration at day 15 was performed for all our patients. Only one patient had re-induction at day 18. Fifteen patients (44%) had more than 5% BMB in day 15. 53% of patients with more than 5% BMB did not achieve a CR compared to 18% with less than 5% BMB. (p=0.05) Induction related mortality was not affected by the results of BMB in day 15. However, the relapse rate was significantly higher in the group of patients with more than 5% BMB at day 15 compared with the other group (66% vs 0%; p=0.002). Summary/Conclusion: Our study showed a significant statistical relation between BMB at day 15 and relapse risk. Thus, the kinetic of bone morrow blast clearance could be correlated to the minimal residual disease at the end of induction and so could predict the risk of relapse.