Unrelated Donor Transplant Recipients Given Thymoglobuline Have Superior GRFS When Compared to Matched Related Donor Recipients Undergoing Transplantation without ATG

Abstract

Recipients of allogeneic hematopoietic stem cell transplantation (HSCT) from unrelated donors (URDs) and mismatched related donors (MMRDs) typically have a higher incidence of acute and chronic graft-versus-host disease (GVHD) compared with matched related donors (MRDs). Anti-T-cell globulins (ATGs) are often used to reduce GVHD in these recipients. We report the outcomes of 211 adult peripheral blood stem cell transplant recipients with myeloid malignancies who received a standardized transplant protocol, in which ATG (Thymoglobuline 4.5 mg/kg) was administered to recipients of URD and MMRD (n = 147) but not MRD (n = 64) transplant. For all patients, incidence of acute GVHD grades 2 to 4 was 21.4%, and chronic GVHD was 35.0%. Two-year overall survival was 63.2% (95% confidence interval, 55.8% to 71.5%), relapse-free survival was 55.3% (47.4% to 64.6%), and GVHD-free, relapse-free survival (GRFS) was 30.7% (23.2% to 40.8%). There were no differences between recipients of MRDs and other donors in relapse, nonrelapse mortality, and overall and relapse-free survival. However, compared with MRD, recipients from URDs and MMRDs had reduced moderate to severe chronic GVHD (10.4% versus 30.1%, P= .002), less chronic GVHD requiring systemic therapy (19.4% versus 38.9%, P = .006), and superior 2-year GRFS (35.5% versus 20.0%, P = .003). In this retrospective review of nonrandomized transplant groups, outcomes of HSCT performed using an URD with ATG during conditioning were superior to transplant from an MRD without ATG. The addition of Thymoglobuline to conditioning in HSCT from MRD should be further examined in prospective trials.

Keywords: Anti-thymocyte globulin; GVHD free; Graft-versus-host disease; Relapse-free survival; Unrelated donor.