A Myeloablative Conditioning Regimen With Fludarabine Demonstrates Good Results In UCBT With Hematologic Malignancies, Especially Acute Lymphoblastic Leukemia

Objectives We retrospectively analyzed the safety and efficacy of a myeloablative conditioning regimen without anti-thymocyte globulin (ATG) or total body irradiation (TBI) but with fludarabine (FLU) in unrelated cord blood transplantation (UCBT) for 30 patients with hematologic malignancies. Methods The myeloablative conditioning regimen consisted of FLU, busulfan (BU) and cyclophosphamide (CY). All of the patients received Cyclosporine (CSA) and mycophenolate mofetil (MMF) as graft versus host disease (GVHD) prophylaxis. Results With this conditioning regimen, we achieved high engraftment rates (96.7%) and rapid hematopoietic reconstitution. Acute GVHD occurred in 12 cases of the 29 engraftment patients (41.4%), and 6 cases (20.7%) were of grade III-IV. Chronic GVHD only occurred in 1 of 28 evaluable patients (3.6%). Twenty-three patients (76.7%) became infected, and 3 cases (10.0%) died of severe infections. Cytomegalovirus (CMV) reactivation occurred in 70.0% of the patients, but no CMV diseases were observed, nor did any patients die of CMV infection. The cumulative incidence of relapse (6.7%) was significantly reduced, and none of the acute lymphoblastic leukemia (ALL) patients relapsed. The 3-year overall survival (OS) and event-free survival (EFS) rates were 73.3% and 70.0%, respectively, representing satisfactory survival. The 3-year OS and EFS of the ALL patients was 75.0%. Discussion This conditioning regimen resulted in a high engraftment rate, rapid myeloid reconstruction and a low incidence of infection. Although there were many patients with high-risk disease and disease progression, the regimen resulted in low relapse rates and good survival. None of the ALL patients relapsed after UCBT, indicating that this conditioning regimen could be applied to more patients with ALL. Disclosures: No relevant conflicts of interest to declare.