Antithymocyteglobulin as prophylaxis of graft failure and graft-versus-host disease in recipients of partially T-cell—depleted grafts from matched unrelated donors: A dose-finding study

Objective In this study, we set out to evaluate the effect of three different antithymocyteglobulin (ATG) doses on graft failure and incidence of graft-vs-host disease (GVHD) among recipients of partially T-cell–depleted (TCD) grafts from matched unrelated donors (MUDs). Patients and Methods Data of 74 consecutively treated MUD recipients were analyzed. Fifty-two, 13, and 9 MUD patients were treated with ATG in a total dose of 8 mg/kg, 6 mg/kg, and 4 mg/kg (given from days −8 until −4), respectively. Results Granulocyte and platelet engraftment were not different between the groups, while graft failure was observed in two patients only (receiving 8 mg/kg and 4 mg/kg ATG, respectively). The cumulative incidence of severe (grade III-IV) acute GVHD and extensive chronic GVHD was 4%, 0%, 44% and 11%, 8%, 44% in groups receiving ATG in a dose of 8 mg/kg, 6 mg/kg, and 4 mg/kg, respectively (severe acute GVHD: p<0.001; extensive chronic GVHD: p = 0.05). Conclusion Based on these findings, we recommend when ATG is used in the setting of stem cell transplantation with (partially) TCD grafts from MUDs, to give a total dose of 6 to 8 mg/kg. A further decrease in dosage resulted in a highly significant increased incidence of severe acute and extensive chronic GVHD.