Prophylactic Donor Lymphocyte Infusion for Relapse Prevention; A Meta-Analysis

Objective: relapsed hematologic malignancies after standard hematopoietic stem cell transplant (HSCT) is one of the most challenging diseases to treat, therefore ongoing research are aiming at relapse prevention and minimizing the transplant related side effects. Prophylactic donor lymphocytes (pDLI) had been proposed as a valuable strategy for relapse prevention but early study results had been discouraging due to association with acute graft-versus-host disease (aGVHD). We attempted to establish the efficacy of pDLI for relapse prevention and define its association with aGVHD.

Method: we searched for titles of articles in MEDLINE (PubMed), Cochrane library, EMBASE database and Google Scholar in May 2019 that evaluated the association between pDLI, relapse and aGVHD. We conducted a random effect meta-analysis of 9 studies involving a total of 748 participants and reported the pooled odd ratio (OR) for incidence of relapse and aGVHD between patients in the pDLI group and the control group.

Result: we found a significantly decreased risk of relapse in the pDLI group versus the control group with a pooled OR of 0.42, 95% CI 0.30-0.58, I²=0% while there is no significantly increased in the risk of aGVHD with a pooled OR of 0.98, 95% CI 0.56-1.72, I²=0.8%

Conclusion: there is significantly decreased risk of relapse in the pDLI group compared to the control group but there is no statistically significant increased risk of aGVHD. We concluded that pDLI is a valuable method of post-transplant relapse prevention for hematologic malignancies and further research is encouraged in a larger population.