Impact Of Pre-Transplant Bone Marrow Blast Percentage On Survival In Acute Myeloid Leukemia Patients

Background and Objectives: Allogeneic hematopoietic stem cell transplantation (alloHSCT) remains the most effective treatment for most of the patients with acute myeloid leukemia (AML). The aim of this study is to investigate the impact of pre-transplant bone marrow blast cell percentage on transplant outcomes and survival. Materials and Methods: One hundred and twenty-two patients with AML who received an alloHSCT in our HSC transplant center between the years of 2001 and 2018 were evaluated. For the estimation of pre-transplant blast percentage, the highest estimate from bone marrow aspirate (by manual count) and core biopsy (pathologist estimates) were used. Results: Of the 122 patients, 97 (79.5%) patients had pre-transplant BM blast cells <5% and 25 patients had pre-transplant BM blast cells 5%40%. Sixty-six patients (54%) underwent a MAC regimen whereas 56 (46%) patients received a RIC regimen. Median follow-up for survivors was 21 months (range 4-203). The 5-year OS for patients who had pre-transplant BM blast cells <5% and patients who had pre transplant BM blast cells 5%-10% were 65% and 18%, respectively (p<0.001). The 5-year disease free survival (DFS) for patients who had pre-transplant BM blast cells <5% and patients who had pre-transplant BM blast cells 5%-10% were 62% and 32%, respectively (p=0.01). Cox regression analysis revealed sex of the patients (p=0.02), ECOG PS of the patients (p=0.006) and developing chronic GVHD (p=0.02) were parameters to predict OS. Cox regression analysis revealed pre-transplant bone marrow blast (%) (p=0.04) as the only parameter to predict DFS. Conclusion: In conclusion, the present study demonstrated that pre-transplant bone marrow blast percentage before alloHSCT is undoubtedly an important prognostic factor for patients with AML. Thus, further studies using more reliable methods to investigate the clinical significance of minimal residual disease at transplant are needed.