Disease-specific impact of anti-thymocyte globulin in allogeneic hematopoietic cell transplantation: a nationwide retrospective study on behalf of the JSTCT, transplant complications working group.

The disease-specific impact of anti-thymocyte globulin (ATG) in allogeneic hematopoietic cell transplantation (allo-HCT) has not been determined. We retrospectively assessed the impact of ATG in allo-HCT using nationwide registry data from the Japan Society for Transplantation and Cellular Therapy. We included patients who received their first allo-HCT between 2007 and 2018 for acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or malignant lymphoma (ML). In total, 8747 patients were included: 7635 patients did not receive ATG and 1112 patients received ATG as GVHD prophylaxis. The median follow-up period of surviving patients was 1457 days. There was no significant impact of pretransplant ATG on the OS or NRM rates in patients with ALL, AML, or ML. In patients with MDS, the probability of 3-year OS was 53.3% in the non-ATG group and 64.2% in the ATG group (P = 0.001). The cumulative incidence rates of relapse and NRM at 3 years were 14.2% and 30.3% (95% CI 27.2-33.3%), respectively, in the non-ATG group and 17.1% and 18.1% in the ATG group (P = 0.15 and P < 0.001). The same finding was observed in a propensity-score matched cohort. Our study suggests that the clinical benefit of ATG could vary among hematological diseases.