Fixed low-dose ATLG in HLA-matched transplantation is safe and effective

Abstract

Background: Graft-versus-host disease (GVHD) remains a major complication following allogeneic hematopoietic stem cell transplantation (HSCT). Anti-Tlymphocyte globulin (ATG), specifically ATLG (Grafalon), is widely used as part of GVHD prophylaxis. While randomized studies recommend high ATLG doses (30 mg/kg for matched related donors [MRD] and 60 mg/kg for matched unrelated [MUD] and mismatched unrelated donors [MMUD]), the optimal dose remains controversial. This study evaluates the efficacy and safety of a fixed low-dose ATLG regimen (21 mg/kg) in HSCT from peripheral blood HLAmatched donors. Methods: We retrospectively analyzed 87 patients with hematologic malignancies who received ATLG at a fixed total dose of 21 mg/kg (7mg/Kg/day on days -3, -2 and -1) as part of GVHD prophylaxis. Donor types included MRD (n=22) and MUD (n=65). The Median follow-up was 31 months. Results: Median age was 58 years, AML (37%) was the main primary disease indication for HSCT, 30% of patients had a High/Very high DRI and 51% had a high HTC-CI (>=3).The cumulative incidence (CI) of acute GVHD grades II-IV by day +100 was 30% (95%CI 21-40) and CI of grades III-IV was 9% (95%CI 416). The 2-year CI of moderate-severe chronic GVHD was 31% (95%CI 21-42). Two-year relapse-free survival (RFS) was 55% (95%CI 44-65). Overall survival (OS) at 2 years was 72% (95%CI 61-81) while transplant-related mortality (TRM) was 14% (95%CI 8-22). Conclusion: A lower fixed low-dose ATLG regimen of 21 mg/kg appears effective and safe for GVHD prophylaxis for HLA-matched HSTC. These findings warrant validation in randomized controlled trials to establish its role in optimizing HSCT outcomes.