Unrelated Umbilical Cord Blood Transplant for Children with ß-Thalassemia Major.

ABSTRACT

Beta thalassemia major, one of the most prevalent hemoglobinopathy throughout the word, can be cured by allogenic stem cell transplantation (SCT) (Bone Marrow Transplant 36971-975, 2005). Many patients, however, lack a suitably matched related sibling donor. Unrelated umbilical cord blood (UCB) can be used as an alternative stem cell source for these patients. This report describes SCT for nine children with beta-thalassemia major using partially HLA-matched unrelated UCB. Conditioning included oral busulfan 16 mg/kg (day -10 to -7), cyclophosphamide (Cy) 200 mg/kg (day -5 to -2), fludarabine 90 mg/kg (day -13 to -11), and antithymocyte globulin (rabbit) 7.5 mg/kg (day -3 to -1). The infused cell dose was 10.71 × 10(7)/kg total nucleated cells (TNC) (range 6.5-17 × 10(7)/kg TNC). The patients ranged in age from 1.5 to 7 years, in weight from 10.5 to 17 kg. A second transplant with two unrelated cord blood units was attempted in two patients who had primary graft failure. The retransplant recipients were preconditioned with i.v Cy 120 mg/kg (day -3 to -2). Five of the nine patients engrafted promptly with 50-100 % donor chimerism (56 %). They engrafted at a median of 17 days (range 12-19). One patient is transfusion free for 36 months; a second patient is transfusion free for 18 months and a third is transfusion free for 9 months. There was no transplant related mortality. Four of the nine children had autologous recovery without engraftment. Primary graft rejection is the major complication. Post transplant complications were mild hepatic veno-occlusive disease, acute GVHD grade II, and CMV interstitial pneumonia. The chronic GVHD was limited and could be controlled by Methylprednisolone combined with Mycophenolate. The lack of a marrow donor registry in India makes UCBT from related and unrelated donors a good alternative. Transplant should be delayed until the child is at least 18 months of age. The dose of UCB stem cells is the most important factor for engraftment. UCB has the advantages of rapid availability and low risk of severe GVHD despite donor-recipient HLA disparity (Transplant Proc 372667-2669, 2005). We demonstrate the feasibility of this procedure in the setting of a developing country.