Clinical Benefit of Low-Dose Antithymocyte Globulin-Thymoglobulin as Graft-versus-Host Disease Prophylaxis in Patients Receiving Allogeneic Peripheral Blood Stem Cell Transplantation from HLA-Identical Donors

Abstract

Graft-versus-host disease (GVHD) is a major complication of allogeneic peripheral blood stem cell transplantation (PBSCT). Previous randomized studies have already shown that several types of antihuman T-lymphocyte immune globulin (ATG) as GVHD prophylaxis can reduce the incidence of acute GVHD and chronic GVHD. However, the efficacy and safety of PBSCT from human leukocyte antigen (HLA)-identical donors with low-dose ATG remain unclear. This study aimed to clarify the efficacy and safety of PBSCT from HLA-identical donors with low-dose ATG compared to PBSCT from HLA-identical donors without ATG. We retrospectively analyzed the outcomes of allogeneic PBSCT from HLA-identical donors with low-dose ATG-thymoglobulin (ATG-T: 2.5 mg/kg) versus PBSCT without ATG-T. Patients' data were collected retrospectively from the medical records of Anjo Kosei Hospital. This study was conducted from 2009 to the final follow-up in October 2022. In total, 47 of 91 patients received ATG-T between January 2009 and March 2020. ATG-T reduced the incidence of moderate-to-severe chronic GVHD (hazard ratio [HR]: 0.15, 95% confidence interval [CI]: 0.057-0.41, p < 0.0010) and non-relapse mortality (HR: 0.21, 95% CI: 0.0058-0.75, p = 0.016) without increasing the risk of relapse. The overall survival did not differ significantly between the two groups. However, the low-dose ATG-T group had better moderate-to-severe chronic GVHD-free, relapse-free survival rates (HR: 0.47, 95% CI: 0.27-0.80, p = 0.0054) than the non-ATG-T group. In addition, the multistate analysis revealed that the low-dose ATG-T group had better current GVHD-free, relapse-free survival at 24 months after transplantation than the non-ATG group (45% [95% confidence interval, CI: 29%-63%) and 21% (95% CI: 9.1%-34%)], respectively, p = 0.015). Low-dose ATG-T did not increase the incidence of infections and adverse events. Low-dose ATG-T could be beneficial for patients receiving PBSCT from HLA-identical donors.