The impact of anti-thymocyte globulin on the outcomes of Patients with AML with or without measurable residual disease at the time of allogeneic hematopoietic cell transplantation

Measurable residual disease (MRD) status pre-allogeneic hematopoietic cell transplantation (allo-HCT) has been shown to predict transplant outcomes. We investigated the effect of Anti-Thymocyte Globulin (ATG) on acute myelogenous leukemia (AML) relapse by pretransplant MRD status. AML patients undergoing allo-HCT in first complete remission from either a matched sibling or unrelated donor during the 2006–2017 period were selected. Outcomes of 1509 patients (MRD+, n = 426) were studied. ATG was used in 561 (52%) and 239 (58%) patients within the MRD− and MRD+ cohorts, respectively. In MRD− patients, ATG did not affect relapse incidence (RI) (HR = 0.80, p = 0.17), but was associated with reduced incidence of grade II–IV acute GVHD, grade II–IV and chronic GVHD, reduced nonrelapse mortality (HR = 0.66, p = 0.05), improved leukemia-free survival (HR = 0.74, p = 0.02), overall survival (HR = 0.69, p = 0.01), and GVHD-relapse free survival (HR = 0.62, p