Influence of conditioning regimen intensity on outcomes post-allogeneic hematopoietic cell transplantation for acute myeloid leukemia in complete morphological remission.

Introduction: The literature comparing outcomes between myeloablative (MAC) and reduced intensity conditioning (RIC) for acute myeloid leukemia (AML) is conflicting.

Methods: We retrospectively analyzed 451 patients who underwent allogenic hematopoietic cell transplantation (alloHCT) for AML in complete remission (CR) with either RIC (n = 331) or MAC (n = 120) with the use of dual T-cell depletion as graft-versus-host disease (GVHD) prophylaxis.

Results: Univariate analysis demonstrated nonrelapse mortality (NRM) at 2 years was 19.1% for MAC and 22.5% for RIC (p = .44). Two-year cumulative incidence of relapse (CIR) was 19.8% for MAC and 24.5% for RIC (p = .15). Two-year overall survival (OS) was 61% and 53% for MAC and RIC, respectively (p = .02). Two-year graft-versus-host disease relapse-free survival (GRFS) was 40.8% for MAC and 33.7% for RIC (p = .30). A propensity score-matched analysis was done matching patients for age, HLA match, in vivo T-cell depletion, and Disease Risk Index (DRI). Two-year OS was 67% for MAC, 66% for RIC (p = .95). A subgroup analysis identified that matched related donor transplants benefit from MAC with OS at 2 years 82.6% versus 57.3% for RIC (p = .006).

Conclusions: In the matched-related donor setting, MAC regimens may offer superior survival. Overall, for our cohort of predominantly in vivo T-cell depleted patients the outcomes of MAC and RIC were similar.