A single-center analysis of chronic graft-versus-host disease-free, relapse-free survival after alternative donor stem cell transplantation in children with hematological malignancies

We assessed the clinical outcomes of allogeneic hematopoietic stem cell transplantation (SCT) from alternative donors for pediatric patients with hematological malignancies, defining graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) as a composite endpoint. We also defined chronic GVHD-free, relapse-free survival (cGRFS) as survival without severe chronic GVHD, relapse, or death. The probabilities of 2-year disease-free survival from a human leukocyte antigen (HLA) matched unrelated donor (n = 57), related donor with HLA-1 antigen mismatch in the graft-versus-host direction (1Ag-GvH-MMRD, n = 28), and unrelated umbilical cord blood (n = 35) were 52.2, 38.5, and 40.4%, respectively (P = 0.14), and for 2-year GRFS were 26.2, 13.4, and 30.4%, respectively (P = 0.089), and for 2-year cGRFS were 36.2, 16.7, and 40.4%, respectively (P = 0.015). Of the three groups, the 1Ag-GvH-MMRD group showed a significantly higher cumulative incidence of severe cGVHD, and was identified as a significant risk factor for worse cGRFS. These results suggest that intensification of GVHD prophylaxis may be needed for SCT from 1Ag-GvH-MMRD. As with GRFS, cGRFS should be used as an endpoint of the clinical study to predict long-term morbidity and mortality for patients who need longer follow-up such as pediatric SCT recipients.