Unrelated Cord Blood Transplantation for Severe Acquired Aplastic Anemia Using a Reduced-Intensity Conditioning: High Graft Rejection but Good Survival

Abstract 2368

We report a single center experience in treating 16 consecutive patients (nine male and seven female) with severe aplastic anemia (AA) who received unrelated cord blood transplantation (UCBT) between 2006 and 2010. The main outcomes of interest were the tolerability and toxicity of UCBT, hematopoietic reconstitution and survival. The first two patients using a conditioning regimen consisting of cyclophosphamide (total dose 120°<<200 mg/kg), rabbit anti-thymocyte globulin (ATG, total dose 10°<<15 mg/kg) and methylprednisolone (total dose 1.5g). The other 14 cases received a reduced-intensity regimen composed of cyclophosphamide (total dose1200mg/©O), ATG (total dose 30 mg/kg) and fludarabine (total dose 120°<<180 mg/m2). Cyclosporine and mycophenolate mofetil were used as GVHD prophylaxis. The median age was 17 years (range 5–61 years) and the median weight was 48 kg (range 16–65 kg). Ten of sixteen were very SAA (VSAA). The median interval between diagnosis and UCBT was 30 days (range, 15–180). All except one did not received ATG-based immunosuppressive therapy before UCBT. Twelve patients received single UCB unit, four cases received double units. Donor/recipient HLA was at least four of six loci matching. The median nucleated cell dose infused was 4.27×10⁷ cells/kg (range 2.34–13.41×10⁷ cells/kg) and CD34⁺ cell dose infused was 2.02×10⁵ cells/kg (range 0.71–4.35×10⁵ cells/kg). Two patients were not evaluable for engraftment because of early death on day +21 and +22 due to severe infection and intracranial hemorrhages, respectively. Only one of the fourteen cases had engraftment with complete chimerism of single UCB unit from day 7, whose ANC© f 0.5 ×10⁹/L and platelet© f20 ×10⁹/L occurred on day 12 and day 31 post double UCBT, respectively. But she experienced secondary graft failure after three months post transplantation and attained survival by successful haplo-identical related transplantation. Thirteen patients experienced primary graft rejection, but all of them acquired autologous recovery. The 3-month and 6-month cumulative incidence of response was 61.5% and 85.7%, respectively. Currently, 14 patients are alive, having survived for 189 to 1712 days (median, 544 days) after their transplantations. The probability of overall survival at 4 years was 87.5%.Our data indicate that UCBT for new diagnosed SAA using no irradiation but fludarabine-based conditioning still seems to be inevitable to led to the high risk of rejection, but may facilitate autologous recovery and improve survival with low risk of transplant-related mortality.