Successful Second Hematopoietic Stem Cell Transplantation Using Total Body Irradiation-Based Conditioning for Children With Transfusion-Dependent Beta-Thalassemia.

BACKGROUND

Graft rejection (GR) occurs in a significant proportion of individuals with transfusion-dependent β-thalassemia (TDT) following hematopoietic stem cell transplantation (HSCT). There have been limited data on the outcome and complications of second HSCT in β-thalassemia patients. The objective was to assess the survival benefits and outcome of second allogeneic HSCT in pediatric TDT patients using Cytoxan (CY) and total body irradiation (TBI) regimen.

METHODS

This was a retrospective study on the analysis of the data for 15 patients who had graft failure over an 18-year period (March 2000 to March 2017) at our institution. For the first failed transplants for patients who had a myeloablative regimen consisting of busulfan (BU)-CY with or without additional anti-thymocyte globulin (ATG), the median age at transplant was 4.2 years. Graft failure occurred over a median of 8.6 months (range, 0.6 - 74.3 months) after the first transplant. The median time to the second transplant from GR was 25.3 months. For the second transplant, the same human leukocyte antigen (HLA) match-related donors for the first HSCT were used. Over half of the patients had moderate to severe iron overload with pre-transplant serum ferritin of 1,405 to 4,051 µg/L at transplant.

RESULTS

Thirteen patients (86.7%) engrafted with thalassemia-free survival (TFS) of 80.0%. One patient rejected the graft and died. Another died due to infectious complications. Apart from a mild chronic graft-versus-host disease (GvHD) in one patient, no serious complications were observed.

CONCLUSION

CY-TBI can be used as conditioning for second HSCT in patients with TDT GR following myeloablative conditioning. We observed overall survival and TFS of 87% and 80% respectively with low rejection rate and mortality, and limited long-term side effects.