Comparison of Conditioning Regimens with or without Antithymocyte Globulin for Unrelated Cord Blood Transplantation in Children with High-Risk or Advanced Hematological Malignancies

• We evaluated the effect of antithymocyte globulin on cord blood transplantation.
• Omission of antithymocyte globulin is associated with faster platelet recovery and fewer cytomegalovirus infections.
• Omission of antithymocyte globulin is associated with lower relapse and improved leukemia-free survival.
• Omission of antithymocyte globulin does not increase the incidence of graft-versus-host disease.

The role and potential efficacy of antithymocyte globulin (ATG) in patients receiving cord blood transplantation (CBT) remain controversial. We retrospectively evaluated the effect of ATG on patient outcomes in 207 children with high-risk or advanced hematological malignancies at 8 child blood disease centers in China. The cumulative incidence of platelet recovery on day 100 was significantly lower in the ATG cohort compared with the non-ATG cohort (77.3% versus 89.8%) (P = .046). There was no significant difference in the incidence of grade II to IV acute and chronic graft-versus-host disease (GVHD), and transplantation-related mortality (TRM) between the 2 groups (P = .76, P = .57, and P = .46, respectively). The incidence of CMV infection was significantly higher among the ATG group compared with that among the non-ATG group (P = .003). The 5-year cumulative incidence of relapse was significantly higher in the ATG cohort (30.7% versus 15.4%) (P = .009). Overall survival in the non-ATG group was slightly higher than that of the ATG cohort (64.1% versus 52.1%, P = .093) and leukemia-free survival in the non-ATG cohort was significantly higher than in the ATG cohort (56.6% versus 37.7%, P = .015). Our study demonstrated that, for high-risk or advanced childhood hematological malignancies receiving unrelated CBT, patients who received conditioning that omitted ATG had a faster platelet recovery, a comparable GVHD and TRM, a significantly lower relapse risk, and an improved long-term survival compared with those patients who received ATG in the conditioning.