Allogeneic cellular gene therapy in hemoglobinopathies--evaluation of hematopoietic SCT in sickle cell anemia

Many patients with thalassemia have been cured with BMT since the first successful transplant in 1981. Allogeneic stem cell gene therapy is the only treatment option for patients with sickle cell anemia (SCA). A total of 11 patients with a median age of 12 years (range, 2-16), affected by SCA, received hematopoietic SCT from HLA-identical, related donors following a myeloablative-conditioning regimen. Indications for transplantation were vaso-occlusive crisis, acute chest syndrome, avascular bone necrosis, chronic RBC transfusions, or hemorrhagic stroke. All patients had sustained engraftment. One patient became a stable mixed chimera with 25% of donor cells at 4 years after transplantation. One patient died at 1 year after transplantation. The probability of survival, SCA-free survival and TRM at 5 years after transplant were 90, 90 and 10%, respectively. All 10 surviving patients remained free of any SCA-related events after transplantation. In conclusion, these data confirm SCT from a suitable HLA-matched, related donor should become the primary option for curing children with SCA. There is an excellent survival rate and a return to normal life, free of SCA-related events.