American Society of Hematology Annual Meeting

RIC vs MAC Conditioning Regimens: No Difference in Outcomes of Allo-HCT for MDS

Jennifer Larson
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ASCT remains the only curative therapy for patients with MDS.
ASCT remains the only curative therapy for patients with MDS.
This study sought to determine if RIC conditioning regimen would lead to better outcomes for patients with MDS undergoing allo-HCT.

Evidence for choosing a reduced intensity conditioning (RIC) regimen over myeloablative conditioning (MAC) for allogeneic hematopoietic cell transplantation (allo-HCT) in patients with myelodysplastic syndromes (MDS) remains weak, according to data presented at the ASH Annual Meeting 2023. 

Researchers sought to learn more about the impact of conditioning intensity on outcomes following allo-HCT in patient with MDS. Therefore, they conducted a retrospective multicenter study to evaluate the use of reduced intensity conditioning (RIC) vs myeloablative conditioning (MAC) in patients with MDS aged 50 and older. 

Studies comparing RIC and MAC outcomes in patient with MDS are rare. Previous cohorts have included both acute myeloid leukemia (AML) and MDS, making it harder to draw conclusions specifically tailored to patients with MDS, explained Ibrahim Yakoub-Agha, MD, PhD, of CHU Lille, in Lille, France. Excluding patients with AML was intended to make it easier to draw conclusions relevant to patients with MDS.

Using the EBMT database, data from 1393 patients from 2014 to 2018 were used for this analysis, including 340 who received MAC and 1053 (75.5%) who received RIC. 

Of the 1393 patients, 922 (66%) were men, median age at the time of allo-HCT was 62.8 years, and 884 (64.3%) had refractory anemia with excess blasts. Median time of follow up was 27.9 months. 

Median OS in the RIC group was 54.2% compared with 46.2% in the MAC group (P =.84). At 36 months, cumulative incidence of relapse for RIC and MAC were 31.2% and 29.7%, respectively, while the cumulative incidence of nonrelapse mortality (NRM) for RIC and MAC were 29.9% and 30.4%, respectively. 

This study’s results could not confirm that RIC was more beneficial than MAC for any particular subgroup, noted Dr Yakoub-Agha. “That could also be because we have limited our study to patients with an age more than 50,” he said. 

Outcomes were not significantly different for patients with MDS older than 50 who underwent the RIC regimen compared with those who underwent the MAC regimen. Hazard ratios were similar in univariate analysis and multivariate analysis of the full cohort and propensity score matching for overall survival, disease-free progression, nonrelapse mortality, and relapse in among patients in this population undergoing a first allo-HCT. 

“Our results are in line with recent published systematic review and meta-analysis where evidence for using one conditioning regimen over another remains weak, so we didn’t or we weren’t able to demonstrate any difference or to identify any subgroup,” concluded Dr Yakoub-Agha.

Reference

Loukili NH, Gras L Sr, Koster L, et al. Conditioning intensity in patients aged > 50 years undergoing allogeneic hematopoietic cell transplantation for myelodysplastic syndrome: a study on behalf of the Chronic Malignancies Working Party of the EBMT. Presented at ASH 2023. December 9-12, 2023. San Diego, CA. Abstract 472.