Background and objectives: Post-transplant cyclophosphamide (PTCy) has shown promising results with low rates of severe graft-versus-host-disease (GVHD), either alone or combined with conventional immunosuppression (CIS). However, studies comparing PTCy with CIS as a GVHD prophylaxis are scarce. The study aimed to determine the rates of GVHD and survival outcomes for patients undergoing peripheral blood stem cell transplant (PBSCT) from HLA-matched related donors (MRD) receiving PTCy-based GVHD prophylaxis and compare these outcomes with those of patients receiving methotrexate (MTX) and cyclosporine-A (CsA) as a GVHD prophylaxis.
Patients and methods: Seventy-five patients with advanced hematologic malignancies who underwent MRD allogeneic hematopoietic cell transplantation (allo-HCT) were analyzed prospectively. These patients received PTCy and CSA as a GVHD prophylaxis (therapeutic group) and their outcomes were compared with those of 75 retrospectively collected patients who received methotrexate and CsA as a GVHD prophylaxis (historical group) from the same two transplant centers.
Results: The median recipient age was significantly lower in the MTX/CsA group at 28 years compared to 34 years in the PTCy/CSA group. Peripheral blood was the only graft source used. All patients had a complete MRD, with two patients having a one-antigen mismatched related donor within the PTCy/CsA group. The 1-year cumulative incidence (CI) of chronic GVHD was 13.4% with PTCy/CsA and 38.6% with MTX/CsA (P = .001). Acute GVHD CI across all grades did not differ between the groups, with 10.7% for PTCy/CsA and 14.7% for MTX/CsA (P = .46). At two years, the overall survival (OS) (54.4% vs 67.2%, P = 0.282), disease-free survival (DFS) (54.1% vs 66.1%, P = 0.358), relapse rates (27.4% vs 20.1%, P = 0.245), and non-relapse mortality (NRM) (29.3% vs 25%, P = 0.904) did not differ between PTCy/CsA and MTX/CsA, respectively.
Conclusion: PTCy-based GVHD prophylaxis in MRD transplant is feasible and leads to lower chronic GVHD rates without causing a significantly different risk of relapse or survival than MTX/CsA. More extensive studies are needed to confirm our results.