[Efficacy of Low-Dose Post-Transplant Cyclophosphamide for GVHD Prophylaxis after Allogeneic Stem Cell...

To evaluate the clinical efficacy and outcomes of low-dose post-transplant cyclophosphamide (PTCY) in preventing graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

A retrospective analysis was conducted on 19 patients who underwent allo-HSCT and received low-dose PTCY for GVHD prophylaxis at the Department of Hematology, Affiliated Hospital of Jiangsu University, between March 2020 and April 2025. Patient demographics, engraftment kinetics, bone marrow chimerism, use of immunosuppressants, incidence of GVHD and other complications, and survival outcomes were analyzed.

The median bone marrow chimerism was 100% at both day +30 and day +90 post-transplantation. All 19 patients achieved successful engraftment. The median time to neutrophil engraftment was 14 days, and the median time to platelet engraftment was 16 days. The median duration of cyclosporine use was 6 months, and the median duration of mycophenolate mofetil (MMF) was 2 months. Acute GVHD (aGVHD) occurred in 8 patients (8/19), and chronic GVHD (cGVHD) occurred in 5 patients (5/19). Among aGVHD cases, three patients (3/8) each had grade 1-2, and two patients (2/8) had grade 3; the median time to aGVHD onset was 25.5 days. Among cGVHD cases, four (4/5) were moderate and one (1/5) was severe, with no mild cases. The median time to cGVHD onset was 14 months. Epstein-Barr virus (EBV) reactivation occurred in 17 patients (17/19), and CMV reactivation occurred in 8 patients (8/19). Hemorrhagic cystitis was observed in 9 patients (9/19), with 4 cases (4/9) of grade Ⅰ, 3 cases (3/9) of grade Ⅱ, and 2 cases (2/9) of grade Ⅲ; no grade Ⅳ cases of hemorrhagic cystitis were reported. The 1-year and 3 year overall survival (OS) rate was 72.6% and 48.4%, respectively. The 1-year and 3-year cGVHD-free survival (GFS) rate was 74.6% and 49.7%, respectively. EBMT risk scores showed no significant correlation with OS or GFS (all P>0.05). At the last follow-up, 13 patients (13/19) remained in disease remission, while two (2/19) had relapsed. A total of six patients (6/19) died, with no deaths attributed to GVHD.

Low-dose PTCY is an effective strategy for preventing GVHD after allo-HSCT without compromising overall treatment efficacy.