Prophylactic Versus Preemptive Donor Lymphocyte Infusion in Refractory/Relapsed AML Post-Allogeneic Transplant: A Retrospective Comparative Study.

Donor lymphocyte infusion (DLI) represents a standard approach for relapse prevention following allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study compared outcomes between prophylactic DLI (Pro-DLI)-administered early post-transplant (median 51 days) to patients in remission without active graft-versus-host disease (GVHD)-and preemptive DLI (Pre-DLI)-triggered by measurable residual disease (MRD) positivity (>0.1% blasts)-in acute leukemia patients. The analysis included 64 patients receiving Pro-DLI and 84 patients managed with Pre-DLI. Notably, the Pro-DLI cohort demonstrated higher 2-year leukemia-free survival (LFS: 56.3% versus 40.5%, P = .045) and markedly reduced 2-year cumulative incidence of relapse (CIR: 23.4% versus 48.8%, P < .001) compared to the Pre-DLI cohort. While Pro-DLI was associated with a higher incidence of chronic GVHD (64.1% versus 40.5%, P < .001), rates of acute GVHD, non-relapse mortality (NRM), and overall survival (OS) did not differ significantly between groups. These findings indicate that early prophylactic DLI significantly improves relapse prevention and long-term leukemia-free survival in refractory/relapsed AML patients post-allo-HSCT, compared to MRD-triggered preemptive DLI.