Sequential Intensified Conditioning and Tapering of Prophylactic Immunosuppressants for Graft-versus-Host Disease in Allogeneic Hematopoietic Stem Cell Transplantation for Refractory Leukemia

For patients with advanced leukemia undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), a major obstacle to success, especially in those with a high leukemia cell burden, is relapse of the underlying disease. To improve the outcome of allo-HSCT for refractory leukemia, we investigated the strategy of sequential intensified conditioning and early rapid tapering of prophylactic immunosupressants therapy for graft-versus-host disease (GVHD) during the early stage after transplantation. A total of 51 patients with refractory leukemia (median age, 30.0 years; unfavorable karyotypes, 49%) received fludarabine (Flu) 30 mg/m²/day and cytarabine 2 g/m²/day (on days −10 to −6), 4.5 Gy total body irradiation (TBI)/day (on days −5 and −4), and cyclophosphamide (Cy) 60 mg/kg/day and etoposide 600 mg/day (on days −3 and −2) for conditioning. Cyclosporine A (CsA) was withdrawn rapidly in a stepwise fashion to avoid overwhelming GVHD reactions if acute GVHD (aGVHD) did not develop at day +30. All 51 patients developed regimen-related toxicities (13 with grade III-IV); 93.9% of them achieved complete remission by day +30. Median follow-up was 41 months (range, 6.6 to 92.2 months); 5-year overall survival (OS) and disease-free survival (DFS) were 44.6% ± 8.1% and 38.2% ± 7.7%, respectively. Thirteen patients relapsed; the 3-year cumulative incidence of leukemia relapse was 33.3%. On multivariate analysis, cytogenetic status was the only significant pretransplantation factor. Survival was better in patients with grade I or II aGVHD than in those without aGVHD. Our data indicate that the sequential strategy of cytoreductive chemotherapy followed immediately by intensified myeloablative (MA) conditioning for allo-HSCT and rapid tapering of prophylactic immunosuppressants for GVHD in the early stage after transplantation has an acceptable toxicity profile and may be a better approach to treating refractory leukemia.

Key Words: Cytoreductive chemotherapy, Myeloablative conditioning, Refractory leukemia