Comparison of Acute Myeloid Leukaemia Transplant Outcomes in Lower and Middle Income Countries with European Society for Blood and Marrow Transplantation (EBMT) Scoring System

Abstract

Objective To evaluate the European Society for Blood and Marrow Transplantation's (EBMT) risk scoring system's prognostic ability for transplant outcomes for AML patients undergoing HSCT in low- and middle-income nations.

Methodology: A retrospective observational single centre study of 46 AML patients who received allogeneic HSCT at AFBMTC, Rawalpindi during December 2013 to August 2022. Data were collected retrospectively from the AFBMTC patient registry however the cut-off date for statistical analysis was February 15, 2024. Patient information such as demographics, transplant parameters (donor type, stem cell source, EBMT score), Disease features (AML ELN risk stratification, cytogenetics), and post-transplant outcomes (engraftment, GVHD, CMV reactivation, mucositis, disease relapse, survival) were gathered. Kaplan-Meier survival analysis was used to estimate OS and DFS and was compared with EBMT risk scores using log-rank test while chi-square test was used to analyse the association of EBMT risk score with incidence of other post-transplant complications and relapse.

Results: Out of the 46 patients who underwent allogeneic HSCT for AML with mean age of 24.59 ± 11.3 years, 27 (58.7%) were males and 19 (41.3%) were females. ELN risk stratification was available for 40 patients among which 15 (37.5%) had favorable risk category, 23 (57.5%) intermediate and 2 (5%) were high risk category. While as per the EBMT score 19(41.3%) were in low risk 25(54.3%) in intermediate risk and only 2(4.3%) in high risk group. The disease free survival (DFS) of the cohort was 39% (median 13.4 months), and overall survival (OS) was 50% (median 16.8 months). The transplant complications included: 26% experiences disease relapse, 39.1% had a GVHD, 41% CMV reactivation, and 15.2% NRM. The EBMT score was correlated significantly with both OS (p=0.05) and DFS (p=0.000) but not with any of the transplant complications. The median OS for low risk was 48.7 months, intermediate risk patients was 24.1 months and was 9 days for high risk patient. Similarly, in the median DFS was 11.3 months for low risk, intermediate risk patients were 13.6 months and 0 days for high risk patients.

Conclusion: Outcomes of hematopoietic stem cell transplantation (HSCT) in a young AML cohort from a resource-constrained environment are highlighted in this study. The results emphasize the influence of donor selection, stem cell source, and post-transplant complications on outcomes, and they confirm the predictive utility of the EBMT risk score. The EBMT score continues to have predictive relevance in LMICs however the high infection complications, TRM (15.2%), and disease relapse (26%) highlights unique challenges faced by countries with limited resources. According to these results, in order to maximize transplant outcomes, modified risk stratification techniques that take into consideration LMIC-specific challenges such as delayed diagnosis, insufficient MRD monitoring, and increased infection risks.