Functional and Radiologic Assessment of the Brain after Reduced-Intensity Unrelated Donor Transplantation for Severe Sickle Cell Disease: Blood and Marrow Transplant Clinical Trials Network Study 0601

Stroke and cognitive decline are hallmarks of sickle cell disease (SCD). The natural history of SCD predicts progressive loss of 1 IQ point per year attributable to disease-related pathology. Hematopoietic cell transplantation (HCT)is curative by reverting to donor-derived erythropoiesis, but evidence that HCT can positively influence disease-induced cognitive decline is lacking. The Sickle Cell Unrelated Transplant Trial prospectively evaluated cognition and brain magnetic resonance imaging (MRI)findings at 2 years after reduced-intensity conditioning followed by unrelated donor HCT. Thirteen study participants completed pre-HCT and post-HCT assessments of intelligence. The mean age of participants was 12.5 ± 3.3 years (range, 6.7 to 17.4 years). Eleven of the 13 recipients completed imaging studies at baseline and post-HCT. Seven had overt stroke pre-HCT, and 1 had an elevated transcranial Doppler velocity with abnormal MRI. The mean Full-Scale IQ was stable: 90.9 ± 13 at baseline and 91.2 ± 13 post-HCT. The mean Performance IQ was 89.9 ± 13 at baseline versus 90.9 ± 13 post-HCT, and mean Verbal IQ was 93.4 ± 13 at baseline versus 93.2 ± 13 post-HCT, respectively. Six recipients had stable MRI; 2 showed resolution of all areas of infarction. Three had additional infarcts post-HCT noted at the 2-year time point. This is the first report describing stabilization of IQ and central nervous system outcomes after unrelated donor HCT despite previous central nervous system morbidity and post-HCT posterior reversible encephalopathy syndrome. These preliminary results post-HCT suggest that HCT may stabilize the cognitive decline of SCD and should continue to be followed over the long term.