Efficacy and safety of rabbit ATLG and ATG in allogeneic hematopoietic stem cell transplantation for children with acquired severe aplastic anemia.

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure syndrome characterized by bone marrow hypoplasia and peripheral blood cytopenia. Without timely treatment, it frequently proves fatal. Rabbit anti-thymocyte globulin (ATG) and anti-human T lymphocyte globulin (ATLG) are widely used for graft-versus-host disease (GVHD) prophylaxis. However, their comparative efficacy in pediatric SAA remains undetermined. This study involved a single-center retrospective analysis of two ATG preparations in pediatric patients undergoing allo-HSCT. The primary endpoint was the incidence of GVHD and viral reactivation following HSCT. Secondary endpoints included overall survival (OS), GVHD-free and failure-free survival (GFFS), neutrophil engraftment, platelet engraftment, hemorrhagic cystitis (HC), tolerability, and toxicities within each group. A total of 124 pediatric SAA patients who underwent their first allo-HSCT between January 2019 and March 2024 were enrolled, with 35 receiving ATLG and 89 receiving ATG. OS, GFFS, GVHD, and HC incidence were comparable between the ATLG and ATG groups (OS: 95.2% vs. 92.9%, P = 0.617). ATLG significantly reduced the incidence of 180-day CMV (45.7% vs. 74.2%, P = 0.0062) and EBV reactivation (29.8% vs. 52.8%, P = 0.025). Additionally, ATLG was associated with fewer adverse events (AEs), including fever (P = 0.009) and rash (P = 0.018). ATLG demonstrated comparable efficacy to ATG in preventing GVHD and achieving OS in pediatric SAA patients undergoing allo-HSCT, while significantly reducing viral reactivation and AEs. These findings support ATLG as a safer alternative, warranting further prospective studies.