ATG- vs alemtuzumab-based GvHD prophylaxis in RIC allo-HSCT for ALL

Results from a European Society for Blood and Marrow Transplantation (EBMT) registry analysis, comparing anti-thymocyte globulin (ATG)- vs alemtuzumab-based graft-versus-host disease (GvHD) prophylaxis in reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (allo-HSCT) for patients aged ≥40 years with acute lymphoblastic leukemia (ALL) in first complete remission (CR1) (N = 357), were published in Bone Marrow Transplantation by Bug et al. The primary endpoint was overall survival (OS).

Key data: In a propensity score-matched analysis (n = 90 per group; median age: ATG group, 60.4 years; alemtuzumab group, 53.6 years), 2‑year OS was similar between ATG and alemtuzumab groups (62.9% vs 62.7%, respectively; hazard ratio [HR], 0.91; p = 0.67), as was 2‑year leukemia-free survival (LFS) (50.7% vs 56.4%; HR, 0.82; p = 0.34). The cumulative incidence of relapse (CIR; 23.9% vs 23.7%; HR, 0.89; p = 0.69) and non-relapse mortality (NRM; 25.4% vs 19.9%; HR, 0.75; p = 0.32) were also similar between groups, resulting in GvHD- and relapse-free survival (GRFS) rates of 42.1% and 48.9% with ATG and alemtuzumab, respectively (HR, 0.80; p = 0.24). No significant difference in the cumulative incidence of acute (aGvHD) or chronic GvHD (cGvHD) was observed between groups.

Key learning: ATG- and alemtuzumab-based GvHD prophylaxis demonstrated comparable survival outcomes and GvHD control in older patients with ALL in CR1 undergoing allo-HSCT, supporting the use of either strategy in the context of RIC regimens in this population.