Reduction of Thymoglobuline from 7.5 mg/kg to 6 mg/kg in conditioning regimen extended time to the first cytomegalovirus detection after allogenic haematopoietic stem cell transplantation.

Introduction: The optimal dosage of anti-thymocyte globulin (ATG) may influence the outcome of patients after allogenic haematopoietic stem cell transplantation (HSCT). The aim of our study was to analyse human cytomegalovirus (CMV) infection data, incidence of graft-versus-host disease and other clinical endpoints comparing two patients' cohorts that were administered two different Thymoglobuline Genzyme doses as part of the HSCT conditioning regimen. Materials and Methods: Total of 65 adult patients received ATG (7.5 mg/kg or 6 mg/kg) as a part of the fludarabine/busultan/ATG conditioning regimen. CMV DNAemia was monitored after HSCT using quantitative real-time PCR and preemptive treatment was started for viral loads above 1000 cp/ml. Results: The mild ATG dose reduction extended the time to the first CMV detection after transplantation (28 days for 7.5 mg/kg dose vs. 40 days for 6 mg/kg dose, p = 0.04). But it did not reduce the incidence or influence first anti-CMV treatment onset, the initial viral load, peak viral load in whole blood or the antiviral therapy parameters (all p >= 0.18). No impact of ATG dose reduction on incidence of graft-versus-host-disease, relapse of underlying disease or mortality within first year after transplantation (all p >= 0.32) were observed. Conclusions: The reduced ATG dosages can allow lower toxicity of conditioning regimen while keeping the performance.