Haematopoietic progenitor cell transplantation in adults with symptomatic sickle cell disease: the time has arrived

Abstract

Alzahrani and colleagues from three different institutions report on the success of non-myeloablative conditioning (alemtuzumab 1 mg/kg/day over five days) and 300 cGy total body irradiation (TBI) and granulocyte colony-stimulating factor (G-CSF) mobilized human leucocyte antigen (HLA)matched sibling peripheral blood haematopoietic progenitor cell transplantation (HPCT) in symptomatic adults with high-risk sickle cell disease (SCD) in this issue of British Journal of Haematology (BJH). Two U.S. centres [National Heart, Lung, and Blood Institute (NHLBI) and University of Illinois, Chicago (UIC)] and one Saudi Arabian institution [King Abdulaziz Medical City (KAMC)] reported on the results of 122 adult SCD recipients: a five-year overall survival (OS) rate of 93% and five-year SCD-free survival rate of 85%. With only single-agent graft versus host disease (GVHD) prophylaxis, sirolimus, only two patients developed Grade I skin acute GVHD (AGVHD) and median time to neutrophil and platelet engraftment was 22 (8–39) and 19 (6–42) days, respectively. Furthermore, with a median follow-up of 4 years (0 6–15), they reported evidence of stable pulmonary and hepatic function, neuroimaging and 21 pregnancies from seven men and seven women. These results compare favourably with previous studies utilizing myeloablative conditioning (MAC) and HLAmatched bone marrow transplantation in children and adults with high-risk SCD. Similarly, the results following reduced toxicity conditioning with HLA-matched cord blood or bone marrow sibling transplantation in children and adolescents with high-risk SCD is comparable to the results reported by Alzahrani and colleagues in adults with high-risk SCD with increased comorbidities (Fig 1). The median OS in adults with SCD ranges from 45 to 50 years of age, which is 25–30 years less than their ethnicand gender-matched controls. Importantly, cardiovascular and pulmonary hypertension and pulmonary dysfunction account for the majority of the long-term complications in adults with SCD and are the leading cause of early mortality. In the study reported by Alzahrani et al., there was no evidence of progression of pulmonary hypertension,