Efficacy and safety of donor lymphocyte infusion after allogeneic hematopoietic stem cell transplantation in pediatric patients

This study evaluates the efficacy and safety of donor lymphocyte infusion (DLI) after allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients. We describe the long-term use of preemptive, prophylactic and therapeutic DLI with a gradual dose increase in half-log increments. Under close monitoring, we increased the DLI dose only in patients who had tolerated the previous dose without any signs of graft-versus-host disease (GVHD). In the preemptive cohort, we were able to prevent hematological relapse by using DLI in ten of the twelve patients (83%) showing minimal residual disease (MRD) positivity. We treated eleven patients with genetic disease and mixed chimerism who were at risk for graft rejection with preemptive DLI. In total, nine patients (82%) responded. Six patients (100%) of the prophylactic cohort with a very high risk of relapse had a successful outcome without relapse or GVHD. Three of the five patients (60%) of the therapeutic cohort were successfully treated with DLI. We observed acute GVHD (grade I and II) in only two patients (6%) who could be cured with immunosuppressive therapy. The results of our study indicate that DLI is a promising strategy and can effectively prevent relapse, graft rejection, and even cure relapse. The observed high response rates in our three cohorts may be attributed to the long-term use of DLI and the very low rate of GVHD to the gradual dose increase. Therefore, we consider DLI as a safe and highly effective therapeutic option when administered in a preemptive, prophylactic or therapeutic setting.