Prophylactic donor lymphocyte infusion after haploidentical hematopoietic cell transplantation and post-transplant cyclophosphamide for treatment of high-risk myeloid neoplasms in children: A retrospective study

BackgroundPost-transplant cyclophosphamide (PTCy) has been recommended for prevention of graft-versus-host disease (GvHD) following haploidentical hematopoietic cell transplantation (haplo-HCT) for treatment of malignant blood diseases, but disease relapse remains a problem. Although donor lymphocyte infusion (DLI) is reported to be effective for treating post-transplantation relapse, the efficacy and safety of prophylactic-DLI (pro-DLI) post haplo-HCT, and PTCy in pediatric patients with hematological malignancies is unknown.MethodsWe retrospectively analyzed the outcomes of 54 pediatric patients with high-risk myeloid neoplasms who received a PTCy regimen for GvHD prophylaxis and pro-DLI after haploidentical peripheral blood stem cell transplantation. The high-risk myeloid neoplasms in this cohort included acute myeloid leukemia (n = 46) and myelodysplastic syndromes (n = 8).ResultsMedian follow-up was for 19.7 (range: 3.4-46.6) months. The cumulative incidences of grade II-IV and III-IV acute GvHD were 37.0% (95% CI: 22.7%-48.7%) and 16.7% (95% CI: 6.1%-26.0%), respectively. There were no graft-failure events, and the 2-year rate of moderate/severe chronic GvHD was 8.1% (95% CI: 0%-16.7%). The 2-year non-relapse mortality, relapse, disease-free survival, GvHD-free relapse-free survival, and overall survival rates were 5.1% (95% CI: 0%-11.7%), 16.6% (95% CI: 5.3%-26.6%), 78.9% (95% CI: 68.0%-91.6%), 62.2% (95% CI: 49.4%-78.3%), and 87.3% (95% CI: 78.3%-97.4%), respectively.ConclusionsProphylactic donor lymphocyte infusion in the setting of haploidentical hematopoietic cell transplantation with post-transplant cyclophosphamide appears to be effective and safe in pediatric patients with high-risk myeloid neoplasms.