Efficacy of low dose antithymocyte globulin on overall survival, relapse rate, and infectious complications following allogeneic peripheral blood stem cell transplantation for leukemia in children.

Antithymocyte globulin (ATG) and anti-T lymphocyte globulin (ATLG) have been widely used to prevent graft-versus-host disease (GvHD), each with distinct properties and noninterchangeable doses. However, the optimal dose of ATG in children undergoing allo-PBSCT for leukemia has not yet been established. Therefore, the impact of ATG dose on overall survival (OS), relapse, GvHD, and infectious complications was investigated. Patients administered high dose (unrelated: 7.5 mg/kg, haploidentical: 10.0 mg/kg) and low dose (unrelated: 3.75 mg/kg, haploidentical: 5.0 mg/kg) ATG during two consecutive time periods were compared. There were 78 (39.8%) patients in the low dose group and 118 (60.2%) in the high dose group. OS was superior in the low dose group compared to the high dose group (P = 0.017), and relapse incidence was significantly lower in the low dose group (P = 0.022). Cumulative incidences of acute and chronic GvHD were similar between the groups (P = 0.095 and P = 0.672, respectively). Cytomegalovirus reactivation (70.3% vs. 51.3%, P = 0.007), Epstein-Barr virus reactivation (81.4% vs. 39.7%, P < 0.001), and invasive bacterial infections (12.7% vs. 0%, P = 0.001) post transplant were more frequent in the high dose group compared to the low dose group. Therefore, low dose ATG is more optimal in pediatric allo-PBSCT providing better OS while lowering the risk of relapse and infectious complications.