The use of haploidentical hematopoietic
cell transplantation (haplo-HCT) with peripheral blood stem cells (PBSCs) to treat
acute myelogenous leukemia (AML) is increasing. We explored whether the addition of
antithymocyte globulin (ATG) to post-
transplantation cyclophosphamide (PTCy) allows better outcomes compared with PTCy alone in haplo-HCT with PBSCs (haplo-PBSCT). We included 441 adult patients undergoing a first haplo-PBSCT for AML in first or second complete remission;
graft-versus-host disease (GVHD) prophylaxis contained either PTCy alone (n = 374) or ATG plus PTCy (n = 67), in addition to
cyclosporine A (CsA) and
mycophenolate mofetil (MMF) as other
immunosuppressive agents. All
transplantations were performed between 2011 and 2019. No major imbalances were observed between the 2 groups. For both groups, the median patient age was 56 years, and the median year of haplo-PBSCT was 2017. Most patients received a reduced-intensity conditioning regimen (57% in the PTCy group and 61% in the ATG+PTCy group; P = .54). The median follow-up was 19 months in the PTCy group versus 15 months in the ATG+PTCy group (P = .59), and the rate of neutrophil engraftment in the 2 groups was 97% and 98%, respectively. In univariate analysis, there were no statistical differences in
transplantation outcomes between the 2 groups. In multivariate analysis, ATG+PTCy was associated with a lower risk of chronic GVHD compared with PTCy alone (hazard ratio, .46; 95% confidence interval, .23 to .93; P = .03). No between-group differences in the other
transplantation outcomes were seen. In haplo-PBSCT, the addition of ATG to PTCy (with CsA and MMF) is feasible and better at preventing chronic GVHD and is associated with survival and
transplantation outcomes comparable to those with PTCy alone, without increasing
transplantation toxicity, mortality, or relapse incidence.