Post-Transplant Cyclophosphamide as Sole Graft-versus-Host Disease Prophylaxis Is Feasible in Patients Undergoing Peripheral Blood Stem Cell Transplantation for Severe Aplastic Anemia Using Matched Sibling Donors

High-dose cyclophosphamide (PTCY) after allogeneic hematopoietic cell transplantation (HSCT) has been shown to be effective in preventing graft-versus-host disease (GVHD) after HLA-matched bone marrow transplantation. We performed a phase II study of PTCY given at 50 mg/kg i.v. on days 3 and 4 as the sole GVHD prophylaxis after HSCT for severe aplastic anemia (SAA) in patients receiving granulocyte colony-stimulating factor-mobilized peripheral blood stern cell (PBSC) grafts from HLA-matched related donors after conditioning with fludarabine, CY, and single-dose total body irradiation. Thirty patients with a median age of 29 years (range, 16 to 49) were enrolled in this study. Engraftment was seen in 27 patients (90%) at a median of 16 days (range, 12 to 21) post-HSCT. None of the patients developed veno-occlusive disease of the liver or hemorrhagic cystitis. Grades II to IV acute GVHD was seen in 22% of patients with grades III to IV GVHD in 11.1%. The 2-year cumulative incidence of chronic GVHD was 22.7%. Fourteen patients (46.6%) did not require any further immunosuppression after receiving PTCY. Comparing with 2 historical cohorts of 30 patients each who received cyclosporine and methotrexate (MTX; at 15 mg/m(2) [MTX15] and 10 mg/m(2) [MTX10]), the incidence of grades II to IV acute GVHD was lower, albeit not significantly, with the use of PTCY (PTCY, 22.2%, vs MTX15, 37.1%, vs MTX10, 53.8%; P=.056), whereas rates of chronic GVHD were significantly reduced (PTCY, 22.7%, vs MTX15, 63.6%, vs MTX10, 76.2%; P=.013). Viral infections including cytomegalovirus were significantly higher with the use of PTCY (60%) compared with cyclosporine and MTX (MTX15, 23.3%, vs MTX10, 33.3%; P=.008). Overall survival was similar between the 3 groups. We conclude that PTCY as the sole GVHD prophylaxis is associated with low rates of acute and chronic GVHD in patients undergoing PBSC transplant for SAA using HLA-matched donors. This trial is registered at CTRI/2010/091/001480. (C) 2017 American Society for Blood and Marrow Transplantation.