Effect of pretransplant leukemic burden in AML patients undergoing allo-SCT in non-CR

On 12 January 2018, in a Correspondence to the Editor of Bone Marrow Transplantation, Hiroyasu Ogawa from Hyogo College of Medicine, Nishinomiya, Japan, and colleagues, reported results of their retrospective study which, investigated the prognostic significance of Bone Marrow (BM) and Peripheral Blood (PB) blast percentage (%)  in Acute Myeloid Leukemia (AML) patients who underwent Allogenic Stem Cell Transplantation (allo-SCT) with a non-Complete Response (CR) status including patients who experienced Primary Induction Failure (PIF), first relapse or second relapse.

Using the Transplant Registry Unified Management Program (TRUMP), the authors identified 3,098 AML patients who underwent allo-SCT in non-CR.  Data on BM and PB blast % before allo-SCT was available for 929 non-CR AML patients and these were evaluated in this study.

The authors first investigated the impact of BM and PM blasts % on survival of patients and observed that both BM and PB blast % significantly correlated with poor overall survival (OS). Hence, to investigate the impact of these factors further on survival and relapse, patients were divided into three groups according to their Leukemic Burden (LB) based on the Hazard Ratio (HR) for survival including; low BM blasts % (BM blasts ≤ 20%) with absence of PB blasts (leukemic burden A), intermediate BM blasts % (20% < BM blasts ≤ 60%) with or without the presence of PB blasts (leukemic burden B), and high BM blasts % (60% < BM blasts) with or without the presence of PB blasts (leukemic burden C).

Key findings:

• Increase in leukemic burden correlated with a stepwise increase in the HR for death
• 2-year OS rate in leukemic burden level A, B, and C were 43.9%, 29.1% , and 20.3% respectively
• Increase in leukemic burden correlated with an increased HR for relapse
• In patients who achieved CR after allo-SCT, compared to leukemic burden level A, there were significantly higher relapse rates observed in leukemic burden levels B (HR = 1.426, P = 0.00380) and C (HR = 1.975, P = 0.0031)
• Non-relapse mortality rates were not significantly different among the leukemic burden levels

The authors noted that their study demonstrated that patients undergoing allo-SCT in non-CR can be classified into three groups using the leukemic burden levels which combines BM blasts% and the presence or absence of PB blasts %. Furthermore, pretransplant leukemic burden levels had a significant impact on relapse and survival rates in patients with AML undergoing allo-SCT in non-CR.

The authors concluded by highlighting that the findings of their study would be valuable information for clinicians transplanting AML patient in non-CR.