Usage of rabbit anti-thymocyte / anti-T-lymphocyte globulins (ATG / ATLG) for hematological malignancies in allogeneic hematopoietic cell transplantation: Best practice recommendations from the EBMT Practice Harmonisation and Guidelines Committee

Rabbit anti-thymocyte globulin (ATG) and anti-T-lymphocyte globulin (ATLG) are widely used in allogeneic hematopoietic cell transplantation (allo-HCT) to prevent graft rejection and reduce the risk of graft-versus-host disease. Despite their broad application, clinical practice varies substantially in terms of product selection, dosing, and timing. Distinct differences in manufacturing, pharmacokinetics, and immunological effects between ATG and ATLG complicate efforts to standardize their use across transplant platforms. This review presents the most recent insights into the pharmacology, mechanisms of action, clinical efficacy, and toxicity profiles of both agents. It highlights their differential impact across various allo-HCT settings. Key topics such as re-exposure, immune reconstitution, adverse events, and individualized dosing strategies guided by pharmacokinetic modeling are discussed. These analyses informed consensus recommendations developed through a dedicated expert workshop within the EBMT to support optimized, context-specific use of rabbit ATG and ATLG in allo-HCT for hematologic malignancies.