Anti-thymocyte globulins for post-transplant graft-versus-host disease prophylaxis-A systematic review and meta-analysis.

Background: Despite advances made in allogeneic hematopoietic stem cell transplantation (alloSCT), graft versus host disease (GvHD) remains a major problem. The main strategy to combat GvHD is prophylaxis and ATG plays a major role in this arena. Conflicting reports on the effectiveness of ATG on GvHD prevention prompted us to address this question by means of a systematic review and meta-analysis.

Methods: Six prospective randomized controlled trials (RCT) comparing the addition of ATG to standard immunosuppressive regimen as GvHD prophylaxis were analyzed. All ATG preparations were considered but homogeneity in type of preparation and dosage had to be observed within each trial.

Results: Our meta-analysis reveals that the incidence of grade II-IV GvHD was significantly lower in patients receiving ATG. Addition of ATG had no impact on overall survival, relapse or non-relapse mortality.

Conclusions: Based on the current level of the data analyzed in this systematic review, we cannot conclude a general recommendation for the use of ATG for GvHD prophylaxis in alloSCT. In patients who are at high risk for severe GvHD it should be considered individually. However, due to the heterogeneity of the analyzable studies it seems likely that future studies might change the results of the pooled data of this meta-analysis. In order to improve the current level of data, further randomized studies in this topic are therefore urgently warranted.