[Antithymocyte globulin for GVHD prophylaxis in allogeneic hematopoietic stem cell transplantation].

Graft versus host disease (GVHD) prophylaxis using antithymocyte globulin (ATG) has been shown for chronic GVHD inhibition effect by a series of randomized control trials in unrelated hematopoietic or peripheral blood stem cell transplantation (PBSCT). Lower doses of ATG have been used in recent studies, although the optimal dose of ATG remains undefined. Consequently, a multicenter phase II study of low-dose ATG (2 mg/kg Thymoglobulin® ) was conducted in patients undergoing human leukocyte antigen-matched PBSCT, showing the safety and efficacy for the prevention of both acute and chronic GVHD. In a nationwide retrospective study for ATG in unrelated PBSCT, the ATG group had a significantly lower incidence of chronic GVHD and a higher probability of GVHD- and relapse-free survival compared with the non-ATG group, although the dose of ATG used was low (1.0-3.0 mg/kg of Thymoglobulin® ). Regarding absolute lymphocyte count (ALC) before the administration of ATG, the incidences of grades III-IV acute GVHD and moderate-to-severe chronic GVHD were significantly higher in patients with high ALC before ATG. Conversely, the relapse rate was significantly higher in patients with low ALC before ATG, suggesting a strategy to individualize ATG dosing by modulating ATG doses according to ALC before ATG.