Comparisons of Modified Post-Transplantation Cyclophosphamide and Granulocyte Colony-Stimulating Factor/Antithymocyte Globulin Regimens for Haploidentical Stem Cell Transplantation in Patients with Aplastic Anemia

Abstract

Haploidentical stem cell transplantation (HSCT) has become an alternative treatment option for patients with aplastic anemia (AA) without matched sibling donors or matched unrelated donors. Recently, post-transplantation cyclophosphamide (PTCy) and granulocyte colony-stimulating factor (G-CSF)/antithymocyte globulin (ATG) regimens have become the most common protocols used worldwide. In this retrospective study, we retrospectively reviewed and analyzed the clinical data of 130 AA patients who underwent haploidentical HSCT and received the modified PTCy (mPTCy) regimen (n = 55) or G-CSF/ATG regimen (n = 75) between January 2013 and June 2021 across 7 transplantation centers. Neutrophil engraftment was successful in all patients within 30 days in the G-CSF/ATG group. The cumulative neutrophil engraftment rate in the mPTCy group was 96.36% (95% confidence interval [CI], 94.57 to 97.57; P = .010). The median time to neutrophil engraftment in the G-CSF/ATG group was 10 days (range, 7 to 28 days), which was more rapid than that observed in the mPTCy group (P < .001). There was no significant difference in the incidence of graft-versus-host disease (GVHD) between the 2 groups. The cumulative incidence of grade II-IV acute GVHD was 18.40% (95% CI, 4.27% to 40.31%) in the mPTCy group and 19.32% (95% CI, 5.86% to 38.58%) in the G-CSF/ATG group, whereas the cumulative incidence of grade III-IV acute GVHD was 7.31% (95% CI, .09% to 37.48%) in the mPTCy group and 7.57% (95% CI, .20 to 34.19) in the G-CSF/ATG group. Similarly, there were no significant between-group differences in overall survival (OS), failure-free survival (FFS), and GVHD-free relapse-free survival (GRFS). The 2-year OS, FFS, and GRFS rates were 95.91% (95% CI, 84.59% to 98.96%), 92.25% (95% CI, 80.59% to 97.03%), and 86.68% (95% CI, 73.98% to 93.44%), respectively, in the mPTCy group and 86.67% (95% CI, 76.64% to 92.59%), 81.28% (95% CI, 70.45% to 88.46%), and 77.20% (95% CI, 65.89% to 85.16%), respectively, in the G-CSF/ATG group. Transplantation-related mortality (TRM) was significantly higher in the G-CSG/ATG group than in the mPTCy group (13.33% versus 1.96%; P = .022). In multivariate analysis, the use of a female donor, a higher Hematopoietic Cell Transplantation Comorbidity Index, and grade III-IV acute GVHD were associated with worse survival outcomes. The mPTCy and G-CSF/ATG regimens led to similar outcomes in AA patients, but quicker engraftment was observed with the ATG/G-CSF regimen, and a lower incidence of TRM was observed with the mPTCy regimen.

Keywords: ATG; Aplastic anemia; Haploidentical transplantation; Post-transplantation cyclophosphamide.