Outcomes of Transplantation with Matched-Related Donor (MRD) and Alternative Donor (AD) Stem Cells in Children with Severe Thalassemia.

Allogeneic stem cell transplant (SCT) from an HLA identical family donor is an accepted option for severe thalassemia. However, the availability of MRD is only 30%. Therefore, AD is another option. The aim of this study is to explore the outcomes of allogeneic SCT with MRD and AD in our institution. We studied 46 consecutive patients (pts) who received MRD (n = 24) or AD; matched unrelated and haploidentical donors (n = 22) stem cells (SCs) for severe thalassemia between September 1992 and July 2004. In MRD group, 3 pts received 1 Ag HLA-mismatched SCs and in AD group, 2 pts received haploidentical SCs. The characteristics of both groups were followed.

The conditioning regimen consisted with busulfan 16 mg/kg, cyclophosphamide 200 mg/kg for MRD and additional ALG (Fresineus) 40 mg/kg for matched unrelated donor (MUD) and CBT and busulfan 8–12 mg/kg, fludarabine 175 mg/m², ALG, + thiotepa, and + total lymphoid irradiation for NST. GVHD prophylaxis was cyclosporin and MTX for MRD, FK 506 and MTX or MMF for MUD, cyclosporin, and prednisolone for CBT, and FK 506 and MMF for NST. The 2 yr thalassemia free survival rate for MRD is 83% and AD 81% (p = 0.6). The 2 yr overall survival rate for MRD is 95% and AD 90 % (p = 0.5). Two (8%) pts of MRD and 2 (9%) of AD had severe acute GVHD grade 3–4. Three pts of MRD had chronic GVHD (2;limited, 1;extensive). Three pts of AD had limited chronic GVHD. Rejection rate of MRD group is 12.5% (n=3). Two of 3 MRD pts who had graft failure after first transplant were successful for second transplant. Rejection rate of AD group is 9% (n=2). In conclusion, the outcomes of transplantation with MRD and AD stem cells in children with severe thalassemia are both equally favorable. Further study should be investigated in a larger group of patients to confirm our findings.