Successful Engraftment of Cord Blood Transplantation Following Reduced-Intensity Conditioning Regimen Using Fludarabine and Busulfan for Advanced Hematologic Malignancies.

Background: The potential role of reduced-intensity cord blood transplantation (RI-CBT) without total body irradiation (TBI) in adults remains unclear. We investigated the feasibility of RI-CBT using non- TBI regimen for the treatment of patients with advanced hematologic malignancies.

Methods: Twenty-three patients (median age, 61, range, 38–74) with advanced hematologic malignancies were enrolled in this study (18 patients in refractory or relapsed phase,5 patients in remission or chronic phase). Conditioning regimen comprised of fludarabine 30 mg/m² on days −8 to −3, busulfan 4 mg/kg p.o. or 3.2 mg/kg i.v. on days −6 to −5. In one cases. we administered busulfan 3.2mg/kg i.v. on days −6 to −3, because of blastic crisis. Graft-versus-host disease (GVHD) prophylaxis was tacrolimus alone. Engraftment was defined as an absolute neutrophil count > 0.5 x 10E9/l. Primary graft failure was defined as the complete loss of donor-type hematopoiesis without engraftment. Secondary graft failure was defined as the loss of donor-type hematopoiesis after primary engraftment. Median follow-up of surviving patients was 1096 days (range, 53–1207). Primary endpoint was engraftment. All patients provided informed consent in accordance with the requirements of Institutional Review Board.

Results: All the patients tolerated the conditioning regimen. Median dose of infused nuclear cells was 2.7x10E7 /kg (range, 1.9–4.6). Twelve patients achieved engraftment at a median of day 20.5 (range, 10–36), but two of them developed secondary graft failure. Complete donor-type chimerism was documented within 30 days of transplant in six patients. Primary graft failure was diagnosed in remaining eleven patients. Six of them, underlying disease progressed despite conditioning regimens. As of August 2007, five patients survived (3 patients in complete remission, one patients relapsed after transplantation, the other one not reached remission). Estimated 1-year overall survival rate was 20.7% (95% confidence interval, 3.0–38.4%).

Conclusions: Though the pre-transplant condition of patients were not good, engraftment was obtained with approximately the half patients. This study demonstrated the feasibility of RI-CBT using non-TBI regimen for adult patients with advanced hematological diseases; however, high incidences of disease progression before engraftment was significant problem. RI-CBT may become the choice of treatment for patients with advanced hematologic malignancies that are incurable with conventional treatments.