Purpose: To evaluate the role of donor lymphocyte infusion (DLI) in the treatment of relapsed acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (HSCT).
Patients and methods: We retrospectively analyzed the data of 399 patients with AML in first hematological relapse after HSCT whose treatment did (n = 171) or did not (n = 228) include DLI. After correction for imbalances and established risk factors, the two groups were compared with respect to overall survival. Further, a detailed analysis of risk factors for survival among DLI recipients was performed.
Results: Median follow-up was 27 and 40 months, respectively. Estimated survival at 2 years (+/- standard deviation) was 21% +/- 3% for patients receiving DLI and 9% +/- 2% for patients not receiving DLI. After adjustment for differences between the groups, better outcome was associated with age younger than 37 years (P = .008), relapse occurring more than 5 months after HSCT (P < .0001), and use of DLI (P = .04). Among DLI recipients, a lower tumor burden at relapse (< 35% of bone marrow blasts; P = .006), female sex (P = .02), favorable cytogenetics (P = .004), and remission at time of DLI (P < .0001) were predictive for survival in a multivariate analysis. Two-year survival was 56% +/- 10%, if DLI was performed in remission or with favorable karyotype, and 15% +/- 3% if DLI was given in aplasia or with active disease.
Conclusion: Although further evidence for a graft-versus-leukemia effect by DLI is provided, our results confirm, that the clinical benefit is limited to a minority of patients. Strategies to reduce tumor burden before DLI, as well as alternative treatment options should be investigated in adults with relapsed AML after HSCT.