Unrelated donor transplantation offers a real curative opportunity for patients with transfusion-dependent thalassaemia. A multicenter retrospective study on behalf of the Spanish group for hematopoietic transplantation and cellular therapy (GETH-TC).

INTRODUCTION

Patients with transfusion-dependent b-thalassaemia (TDT) suffer from severe anemia, both primary and secondary iron overload and end-organ damage. Although new disease-modifying and curative therapies are emerging, hematopoietic stem cell transplantation (HSCT) remains the most widely available curative option for TDT patients. This study aims to compare HSCT outcomes according to the type of donor used, considering not only survival, but also graft-versus-host disease (GVHD) and other transplant-related complications.

METHODS

A multicentre retrospective study was conducted, in which children who received a first HSCT for TDT were included.

RESULTS

Fifty-eight patients were included, with a median follow-up of 7.4 years. The median age at HSCT was 5.6 years (range 0.76-16.64). Thirty-nine patients received a matched family donor (MFD) transplant, and 19 received an unrelated donor transplant of whom 16 received a fully matched unrelated donor (MUD) and 3 a mismatched unrelated donor cord blood (CB) transplant. Most patients received bone marrow alone or in combination with CB (n = 49); six patients received CB, and 3 patients' peripheral blood. Thirty-six patients received busulfan, while the remaining patients received a treosulfan-based conditioning regimen. The incidence of grade II-IV acute GVHD was significantly higher in the MUD group than in the MFD group (56.25% vs. 25.71%, P = 0.0178). No significant differences were found in grade III-IV acute GVHD or chronic GVHD. Although the incidence of endothelial complications was higher in patients receiving an MUD transplant, it was not statistically significant. With 2-year overall survival (OS), thalassaemia free survival (TFS) and chronic GVHD thalassaemia-free survival of 98%, 92.2% and 82.7%, respectively, there were no differences between the MFD and MUD groups.

CONCLUSION

Fully matched unrelated donor transplantation may offer a real curative opportunity for pediatric patients with TDT who lack an MSD, with excellent OS, TFS and low incidence of grade III-IV acute and chronic GVHD. Future research into the prevention and treatment of GVHD will further improve these results.