Single-Unit Umbilical Cord Blood Transplantation from Unrelated Donors in Adult Patients with Chronic Myelogenous Leukemia

Clinical studies focused on outcomes of umbilical cord blood transplantation (UCBT) for patients with chronic myelogenous leukemia (CML) in need of allogeneic stem cell transplantation and lacking an HLA-matched adult donor are limited. We analyzed the outcome of 26 adults with CML receiving single-unit UCBT from unrelated donors after myeloablative conditioning at a single institution. Conditioning regimens were based on combinations of thiotepa, busulfan, cyclophospamide or fludarabine, and antithymocyte globulin. At the time of transplantation, 7 patients (27%) were in first chronic phase (CP), I I (42%) were in second CP, 2 (8%) were in accelerated phase (AP), and 6 (23%) were in blast crisis (BC). The cumulative incidence (Cl) of myeloid engraftment was 88% at a median time of 22 days and was significantly better for patients receiving higher doses of CD34(+) cells. The Cl of acute graft-versus-host disease (GVHD) grade II-IV was 61%, that of acute GVHD grade III-IV was 39%, and that of chronic extensive GVHD was 60%. Treatment-related mortality (TRM) was 41% for patients undergoing UCBT while in first or second CP and 100% for patients in AP or BC (P < .01). After a median follow-up of 8 years, none of the patients relapsed, giving an overall disease-free survival (DFS) at 8 years of 41%. The DES for patients undergoing UCBT while in any CP was 59%. These results demonstrate that UCBT from unrelated donors can be a curative treatment for a substantial number of patients with CML. Advances in supportive care and better selection of cord blood units and patients are needed to improve TRM.