Efficacy of a Modified Post-Transplant Cyclophosphamide Regimen for Unrelated Donor Hematopoietic Stem Cell Transplantation in Patients with Severe Aplastic Anemia: A Prospective Study

The aim of the present study was to examine the efficacy of the modified post-transplant cyclophosphamide (PTCy) regimen, which involved reducing the Cy dose to 40 mg on days +3 and +4 in patients with severe aplastic anemia (SAA) subjected to unrelated donor allogeneic hematopoietic stem cell transplantation (URD-HSCT). For this purpose, a prospective single-center trial was conducted and the clinical outcomes were collected from 30 patients with SAA treated with the modified PTCy regimen for URD-HSCT. The median time to neutrophil and platelet engraftment was 13 days (range, 11 to 16) and 12 days (range, 5 to 33), respectively. The cumulative incidence of neutrophil and platelet engraftment was 93.1% f 0.3% and 96.6% f 0.2%, respectively. The 2-year overall survival (OS) was 97% (95% confidence interval [CI]: 90%-100%] and 2-year graft-versus-host disease (GVHD) and rejection-free survival (GRFS) was 93% (95% CI: 85%-100%). The incidence rates of acute GVHD (aGVHD) and chronic GVHD (cGVHD) were 13.8 f 0.4% and 10.3 f 0.3%, respectively, and no patients developed grades III-IV aGVHD. However, only one patient developed a moderate extensive cGVHD. The incidence of reconstitution varies among different subsets of immune cells after URD-HSCT. Natural killer (NK) cells recover first, followed by CD8+ T and CD19+ B cells, and finally CD4+ T cells. In conclusion, the present study demonstrates that the modified PTCy regimen, with a reduced dose of 40 mg on days +3 and +4, may be an effective regimen for URD-HSCT in patients with SAA and reduce the occurrence of the GVHD. (c) 2024 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.