Low-dose anti-thymocyte globulin reduce severe acute and chronic graft-versus-host disease after allogeneic stem cell transplantation.

backgroundAnti-thymocyte globulin (ATG) administered at 5-10 mg/kg can prevent graft-versus-host disease (GVHD). We sought to investigate the potential for lower doses of ATG to decrease non-relapse mortality (NRM).

methodsWe consecutively compared the outcomes of patients with hematological diseases who received allogeneic stem cell transplants from allogeneic related or unrelated donors before February 2010 and were not administered ATG (reference arm), with those administered 2.5 mg/kg ATG after March 2010 (treatment arm).

resultsWe recruited 19 patients into each arm (median age 49 years, range 19-64). 16 patients received myeloablative preparation regimens and 22 patients received toxicity-reduced preparation regimens. All but one patient achieved engraftment, and one secondary graft failure was observed. Overall incidence of acute and chronic GVHD were 63.2 and 15.8%, respectively, in the ATG arm (21.1% grade II to IV, and 0.0% grade III/IV acute GVHD), and 57.9 and 47.4%, respectively, in the reference arm (31.6% grade II to IV, and 21.1% grade III/IV acute GVHD). The estimated probability of overall survival (OS) at 6 years and relapse rate 3 years after transplantation were 49.2 and 26.3% for the ATG arm, respectively, and 54.2 and 21.1% for the reference arm, respectively. The rate of NRM was 10.5% in the ATG arm and 26.3% in the reference arm. No patients died as a result of acute or chronic GVHD.

conclusionsLow-dose ATG may suppress severe acute GVHD and chronic GVHD without increasing NRM, and can be used safely for Japanese patients receiving transplants from HLA-matched donors.