Allogeneic transplantation strategies including haploidentical transplantation in sickle cell disease.

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy. Despite antenatal counseling and neonatal screening programs implemented in higher income countries, SCD is still associated with multiple morbidities and early mortality. To date, the only curative approach to SCD is hematopoietic stem cell transplantation, but this therapy is not yet established worldwide. The registries of the European Blood and Marrow Transplant (EBMT) and the Centre for International Blood and Marrow Transplant Research (CIBMTR) account, respectively, for 611 and 627 patients receiving transplantations for SCD. Most of these patients were transplanted with grafts from an HLA-identical sibling donor. The main obstacles to increasing the number of transplantations are a lack of awareness on the part of physicians and families, the absence of reliable prognostic factors for severity, and the perceived risk that transplantation complications may outweigh the benefits of early transplantation. Results show that more than 90% of patients having undergone an HLA-identical sibling transplantation after myeloablative conditioning are cured, with very limited complications. Major improvement is expected from the use of new reduced-toxicity conditioning regimens and the use of alternative donors, including unrelated cord blood transplantations and related haploidentical bone marrow or peripheral blood stem cell transplantations.