Effective prevention of GVHD using in vivo T-cell depletion with anti-lymphocyte globulin in HLA-identical or -mismatched sibling peripheral blood stem cell transplantation.

To investigate the impact of anti-lymphocyte globulin (ATG-Fresenius) as part of the HLA-sibling transplantation, we evaluated 238 patients (median age 48 years) with different diagnoses (AML, ALL, CML and lymphoproliferative disorders). A total of 79 patients received ATG and 159 patients did not. In the ATG group, there were more HLA-mismatched donors (6% vs 1%, p=0.02), bad risk patients (70% vs 55%, P=0.04), reduced intensity conditioning (RIC) regimens (65% vs 34%, P=<0.001) and older patients (median age 51 vs 48 years, P=0.002). The median time to leukocyte engraftment was significantly faster in the non-ATG group (13 vs 15 days, P < 0.001). EBV reactivation was more often seen in the ATG group (9% vs 2%, P=0.05). Cumulative incidence of acute and chronic GVHD was less observed in the ATG group (27% vs 40%, P=0.004, and 33% vs 54%, P=0.002). The cumulative incidence rates of non-relapse mortality and of relapse at 5 years were 20 and 34%, respectively, for ATG and 34 and 29%, respectively, for non-ATG (P=0.06 and P=0.3). ATG can prevent GVHD without an obvious risk of relapse but should be confirmed in a randomized study.