The Role of Donor Leukocyte Infusions in the Treatment of Relapsed Acute Leukemia after Allogeneic Stem Cell Transplantation: A Retrospective Analysis

: Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only treatment offered for acute leukemias with potential curative capability. One of the main reasons of treatment failure in patients after allo-HSCT is return of the primary disease. This study aimed to evaluate the role of different modalities available to treat the patients with relapsed acute leukemia after allo-HSCT, focusing mainly on donor leukocyte infusions (DLIs). Materials and Methods: This study included 277 patients who relapsed after myeloablative allo-HSCT between February 2003 and February 2015. Treatment option was offered to all patients, but it was not accepted by about one-third of the study participants. Treated patients were categorized based on receipt of DLI (DLI-based vs. non DLI-based). The effect of treatment in all patients and then the effect of DLI among the treated group was evaluated. Kaplan-Meier method was used for calculating survival rates. All patients were relapsed cases, thus only overall survival (OS) was calculated.Results: One hundred and forty-five ALL patients and 132 AML patients were included in the study. One year survival rate for treated patients was 25.13% and for patients who received best supportive care was 2.79% (P<0.001). The difference was significant in both AML and ALL groups. Using DLI-based treatments were accompanied by a noticeably superior outcome. Hazard ratio was 0.43 (0.29-0.63) for DLI-based treatments (P<0.001). Conclusion: Despite the poor prognosis of relapsed acute leukemia after HSCT, it seems that treatment interventions and, especially DLI-based treatments, can be of substantial benefit for patients.