Matched comparison of therapeutic DLI and second allogeneic transplantation after relapse of acute leukemia or MDS

Background Relapse is the main cause of treatment failure after allogeneic hematopoietic cell transplantation (allo-HCT). Therapeutic donor lymphocyte infusion (DLI) and second allo-HCT are common post-relapse options, but comparative evidence from the time of relapse is limited. Methods We retrospectively analyzed 85 adults with acute leukemia or myelodysplastic syndromes (MDS) who received therapeutic DLI or a second allo-HCT after relapse (2010–2022). DLI required hematologic or clinical relapse. Overall survival (OS) was assessed using Kaplan–Meier analysis, Cox regression, and propensity score matching (PSM). Competing risks models evaluated relapse-related mortality (RRM) and non-relapse mortality (NRM). Results 60 patients received DLI and 25 underwent a second allo-HCT. No significant difference in OS was observed between groups (median OS 0.92 vs. 0.61 years, p=0.295). DLI showed higher RRM, while second allo-HCT showed a trend toward higher NRM. In the matched cohort (n = 36), OS remained numerically longer after second allo-HCT without significance. Conclusion OS did not differ between second allo-HCT and therapeutic DLI. Treatment should be individualized, and larger multicenter studies are needed to refine patient selection.