Mismatched unrelated donors allogeneic hematopoietic stem cell transplantation with antithymocyte globulin for hematological malignancies: a multicenter retrospective study in China.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) utilizing mismatched unrelated donors (MMUD) present a vital option for patients with hematologic malignancies without human leukocyte antigen (HLA)-matched donors. This multicenter retrospective study encompassed 211 adults with hematological malignancies receiving allo-HSCT with antithymocyte globulin (ATG) from ≥1 HLA locus MMUD. The findings revealed cumulative incidences of II-IV acute graft-versus-host disease (GVHD) at 180 days at 26.5%, and III-IV acute GVHD at 12.3%, with 3-year cumulative incidences for total and moderate-severe chronic GVHD at 37.0% and 21.0%. The 3-year non-relapse mortality (NRM) and relapse rates were 19.7% and 25.8%. The study reported a 3-year overall survival (OS) rate of 63.1%, a disease-free survival (DFS) rate of 54.5%, and a GVHD-free, relapse-free survival (GRFS) rate of 40.8%. Administration of a lower-dose ATG-Genzyme (ATG-G, ≤ 6 mg/kg) correlated with improved engraftment without significantly affecting survival, relapse, or viral reactivation rates. The quantity of HLA mismatches did not impact engraftment, GVHD, viral reactivation, OS, DFS, GRFS, relapse, or NRM. In conclusion, MMUD allo-HSCT with ATG demonstrates favorable outcomes for patients with hematological malignancies, with no evident correlation between the degree of mismatch and post-transplantation results. Utilizing a lower dose of ATG-G ( ≤ 6 mg/kg) proved efficacious, delivering comparable clinical advantage.