Enhanced Long-Term Brain Magnetic Resonance Imaging Evaluation of Children with Sickle Cell Disease after Hematopoietic Cell Transplantation

Effect of allogeneic hematopoietic stem cell transplantation on sickle cell disease-related organ complications: A systematic review and meta-analysis

Sickle cell disease (SCD)-related organ complications are a major cause of morbidity and mortality in patients with SCD. We sought to assess whether hematopoietic stem cell transplantation (HSCT) stabilizes, attenuates, or exacerbates organ decline. We performed a systematic review and meta-analysis of trials investigating organ function before and after HSCT in patients with SCD. We searched MEDLINE/PubMed and EMBASE up to September 21, 2023. Continuous data were expressed as standardized mean difference (SMD) and pooled in a weighted inverse-variance random-effects model; binomial data were expressed as risk ratio (RR) using the Mantel-Haenszel random-effects meta-analyses. Of 823 screened studies, 34 were included in this review. Of these, 17 (774 patients, 23.6% adults, 86.3% HLA-identical sibling donor, 56.7% myeloablative conditioning regimen) were included in the meta-analyses. Pulmonary function remained stable. Mean tricuspid regurgitant jet velocity decreased but did not reach statistical significance. In children, estimated glomerular filtration rate decreased (SMD -0.80, p = .01), and the presence of proteinuria increased (RR 2.00, p = <.01), while splenic uptake and phagocytic function improved (RR 0.31, p = <.01; RR 0.23, p = <.01). Cerebral blood flow improved (SMD -1.39, p = <.01), and a low incidence of stroke after transplantation in high-risk patients was found. Retinopathy and avascular osteonecrosis were investigated in only one study, showing no significant changes. While HSCT can improve some SCD-related organ dysfunctions, transplantation-related toxicity may have an adverse effect on others. Future research should focus on identifying individuals with SCD who might benefit most from HSCT and which forms of organ damage are more likely to exacerbate post-transplantation.

Neurocognitive outcome in children with sickle cell disease after myeloimmunoablative conditioning and haploidentical hematopoietic stem cell transplantation: a non-randomized clinical trial

Background

Due to the risk of cerebral vascular injury, children and adolescents with high-risk sickle cell disease (SCD) experience neurocognitive decline over time. Haploidentical stem cell transplantation (HISCT) from human leukocyte antigen-matched sibling donors may slow or stop progression of neurocognitive changes.

Objectives

The study is to determine if HISCT can ameliorate SCD-associated neurocognitive changes and prevent neurocognitive progression, determine which specific areas of neurocognitive functioning are particularly vulnerable to SCD, and determine if there are age-related differences in neurocognitive functioning over time.

Methods

We performed neurocognitive and neuroimaging in SCD recipients following HISCT. Children and adolescents with high-risk SCD who received parental HISCT utilizing CD34+ enrichment and mononuclear cell (T-cell) addback following myeloimmunoablative conditioning received cognitive evaluations and neuroimaging at three time points: pre-transplant, 1 and 2 years post-transplant.

Results

Nineteen participants (13.1 ± 1.2 years [3.3-20.0]) received HISCT. At 2 years post-transplant, neuroimaging and cognitive function were stable. Regarding age-related differences pre-transplantation, older children (≥13 years) had already experienced significant decreases in language functioning (p < 0.023), verbal intelligence quotient (p < 0.05), non-verbal intelligence quotient (p < 0.006), and processing speed (p < 0.05), but normalized post-HISCT in all categories.

Conclusion

Thus, HISCT has the potential to ameliorate SCD-associated neurocognitive changes and prevent neurocognitive progression. Further studies are required to determine if neurocognitive performance remains stable beyond 2 years post-HISCT.Clinical trial registration: The study was conducted under an investigator IND (14359) (MSC) and registered at clinicaltrials.gov (NCT01461837).

Functional near-infrared spectroscopy-based prefrontal cortex oxygenation during working memory tasks in sickle cell disease

Significance

Sickle cell disease (SCD), characterized by painful vaso-occlusive crises, is associated with cognitive decline. However, objective quantification of cognitive decline in SCD remains a challenge, and the associated hemodynamics are unknown.

Aim

To address this, we utilized functional near-infrared spectroscopy (fNIRS) to measure prefrontal cortex (PFC) oxygenation responses to N -back working memory tasks in SCD patients and compared them with healthy controls.

Approach

We quantified the PFC oxygenation rate as an index of cognitive activity in each group and compared them. In half of the participants, a Stroop test was administered before they started N -back to elevate their baseline stress level.

Results

In SCD compared to healthy controls, we found that (1) under a high baseline stress level, there were significantly greater oxygenation responses during the 2-back task, further elevated with histories of stroke; (2) there was a marginally slower N -back response time, and it was even slower with a history of stroke; and (3) the task accuracy was not different.

Conclusions

Additional requirements for processing time, PFC resources, and PFC oxygenation in SCD patients offer an important basis for understanding their cognitive decline and highlight the potential of fNIRS for evaluating cognitive functions.

Neuropsychological, behavioral, and quality-of-life outcomes in children and adolescents with sickle cell disease treated with nonmyeloablative matched sibling donor hematopoietic cell transplantation: A case series

BACKGROUND/OBJECTIVES

Despite advances in the treatment of sickle cell disease (SCD), cerebrovascular and cognitive insults can have lifelong consequences. Hematopoietic cell transplantation (HCT) is an established curative therapy, and recent studies have demonstrated efficacy with reduced toxicity nonmyeloablative (NMA) regimens, but little is known about neuropsychological outcomes. The objective of this study was to describe neuropsychological, behavioral, and quality-of-life outcomes with medical correlates in children with SCD who received an NMA matched sibling donor (MSD) HCT.

DESIGN/METHODS

Retrospective cohort analysis of nine recipients with hemoglobin SS SCD who underwent MSD HCT using the National Institutes of Health (NIH) NMA protocol.

RESULTS

Mean full-scale intellectual functioning (FSIQ) was average pre-HCT (FSIQ = 92.1, SD 9.0; n = 8) and 2 years post-HCT (mean FSIQ = 96.6; SD 11.1; N = 9). Neuropsychological functioning was largely average across all cognitive domains, and no pre/post-HCT differences were found to be statistically significant given the small sample size. However, effect sizes revealed moderate improvements in processing speed (Cohen's d = .72) and verbal memory (Cohen's d = .60) post-HCT, and declines in measures of attention (Cohen's d = -.54) and fine motor speed and dexterity (Cohen's d = -.94). Parents endorsed better quality of life (Cohen's d = .91), less impact of SCD on their family, and less worry about their child's future (Cohen's d = 1.44).

CONCLUSION

Neuropsychological functioning in a sample of children and adolescents treated uniformly with NMA MSD HCT remained stable or improved in most cognitive domains, and improvements in quality of life and family functioning were observed.

Editing outside the body: Ex vivo gene-modification for β-hemoglobinopathy cellular therapy

Genome editing produces genetic modifications in somatic cells, offering novel curative possibilities for sickle cell disease and β-thalassemia. These opportunities leverage clinical knowledge of hematopoietic stem cell transplant and gene transfer. Advantages to this mode of ex vivo therapy include locus-specific alteration of patient hematopoietic stem cell genomes, lack of allogeneic immune response, and avoidance of insertional mutagenesis. Despite exciting progress, many aspects of this approach remain to be optimized for ideal clinical implementation, including the efficiency and specificity of gene modification, delivery to hematopoietic stem cells, and robust and nontoxic engraftment of gene-modified cells. This review highlights genome editing as compared to other genetic therapies, the differences between editing strategies, and the clinical prospects and challenges of implementing genome editing as a novel treatment. As the world's most common monogenic disorders, the β-hemoglobinopathies are at the forefront of bringing genome editing to the clinic and hold promise for molecular medicine to address human disease at its root.

Hematopoietic stem cell transplantation reverses white matter injury measured by diffusion-tensor imaging (DTI) in sickle cell disease patients

Brain injury in sickle cell disease (SCD) comprises a wide spectrum of neurological damage. Neurocognitive deficits have been described even without established neurological lesions. DTI is a rapid, noninvasive, and non-contrast method that enables detection of normal-appearing white matter lesions not detected by conventional magnetic resonance imaging (MRI). The aim of the study was to evaluate if stem cell transplantation can revert white matter lesions in patients with SCD. Twenty-eight SCD patients were evaluated with MRI and DTI before and after allogeneic hematopoietic stem cell transplantation (HSCT), compared with 26 healthy controls (HC). DTI metrics included fractional anisotropy (FA), mean diffusivity (MD), radial (RD), and axial (AD) diffusivity maps, global efficiency, path length, and clustering coefficients. Compared to HC, SCD patients had a lower FA (p = 0.0086) before HSCT. After HSCT, FA increased and was not different from healthy controls (p = 0.1769). Mean MD, RD, and AD decreased after HSCT (p = 0.0049; p = 0.0029; p = 0.0408, respectively). We confirm previous data of white matter lesions in SCD and present evidence that HSCT promotes recovery of brain injury with potential improvement of brain structural connectivity.

Low Rates of Cerebral Infarction after Hematopoietic Stem Cell Transplantation in Patients with Sickle Cell Disease at High Risk for Stroke

Hematopoietic stem cell transplantation (HSCT) can be curative for sickle cell disease (SCD). SCD patients with cerebrovascular disease are often referred for HSCT. The objective of this study was to describe neurologic outcomes after HSCT in patients with pre-existing SCD and cerebrovascular comorbidity. Patients with SCD treated with HSCT at a single center between 1996 and 2019 were identified. Patients with cerebral ischemia and/or vasculopathy before undergoing HSCT were included. Patients with graft failure were excluded. The cohort was divided into 3 groups: symptomatic stroke, vasculopathy without symptomatic stroke, and isolated silent cerebral infarction (SCI). Magnetic resonance imaging/angiography and neurologic assessments pre- and post-HSCT were analyzed to assess outcomes. In a cohort of 44 patients, there were 25 with symptomatic infarction, 10 with vasculopathy, and 9 with isolated SCI. Post-HSCT ischemic injury (2 symptomatic strokes, 2 SCIs) was identified in 4 patients, all with previous symptomatic infarction. Within this group (n = 25), the post-HSCT incidence of subsequent symptomatic infarction was 1.6 events/100 patient-years, and SCIs occurred at a rate of 2.2 events/100 patient-years. No patient had progression of vasculopathy post-HSCT. Our data show a low incidence of new ischemic injury after successful HSCT for SCD. Patients with a history of both symptomatic stroke and vasculopathy are at greatest risk for post-HSCT ischemic injury.

A systematic review of quality of life in sickle cell disease and thalassemia after stem cell transplant or gene therapy

Patients with sickle cell disease (SCD) and thalassemia experience several complications across their lifespan that lead to impairment in different health-related quality of life (HRQOL) domains. There is increasing interest in curative therapies for patients with SCD and thalassemia, including hematopoietic stem cell transplant (HSCT) and gene therapy; however, the effect of these therapies on various HRQOL domains remains unclear. Our objective was to systematically evaluate the most recent evidence for the effect of HSCT and gene therapy on HRQOL in patients with SCD and thalassemia. A systematic search of medical literature databases was conducted. A total of 16 studies (thalassemia, n = 9; SCD, n = 6; both, n = 1) involving 517 participants met inclusion criteria (thalassemia, n = 416; SCD, n = 101). HSCT was associated with a small to large positive effects in most HRQOL domains (Cohen's d; mean = 0.47; median = 0.37; range, 0.27-2.05). In thalassemia, HSCT was frequently associated with large positive effects in physical and emotional HRQOL domains (median d = 0.79 and d = 0.57, respectively). In SCD, HSCT was associated with large positive effects in all HRQOL domains. Emerging data suggest improvement in HRQOL outcomes across different domains following gene therapy in thalassemia and SCD. The quality of evidence was moderate in 13 studies (81%). HSCT has a positive impact on several HRQOL domains in patients with SCD and thalassemia; however, more longitudinal studies are warranted to assess the sustainability of these effects. Reporting HRQOL outcomes from ongoing gene therapy or gene-editing trials in SCD and thalassemia is key to better understand the benefits of such therapies.

Patient-reported Outcome Measures in Pediatric Non-Malignant Hematology: A Systematic Review

Patient-reported outcome measures (PROMs) are questionnaires completed by patients or caregivers without influence by health care professionals. As such, PROMs show subjective health experiences, enhance the clinical information available to providers, and inform clinical action. The objective of this systematic review is to identify and list which validated PROMs have been used to monitor health-related quality of life in pediatric patients with nonmalignant hematology (hemophilia, immune thrombocytopenia, sickle cell disease, and thalassemia). Databases (MEDLINE, Embase, HaPI, CINAHL, and PsycTESTS) were searched to identify publications that validated or used PROMs as an outcome measure in the 4 disease groups. Overall, 209 articles met the inclusion criteria, identifying 113 PROMs. Of the 113 identified PROMs, 95 are generic and can be used in multiple disease groups. The Pediatric Quality of Life Generic Core Scales was the most frequently used generic PROM (68 studies). The 18 remaining PROMs were disease specific. The results of this review, together with the COSMIN tool for selecting outcome measures, will allow clinicians to evaluate the PROMs that are best suited to their patient population. In addition, the focus groups are currently being conducted with patients, parents, and clinicians to determine the optimal use of PROMs in the clinical environment.

Improved stenosis outcome in stroke-free sickle cell anemia children after transplantation compared to chronic transfusion

We report here the 3-year stenosis outcome in 60 stroke-free children with sickle cell anaemia (SCA) and an abnormal transcranial Doppler history, enrolled in the DREPAGREFFE trial, which compared stem cell transplantation (SCT) with standard-care (chronic transfusion for 1-year minimum). Twenty-eight patients with matched sibling donors were transplanted, while 32 remained on standard-care. Stenosis scores were calculated after performing cerebral/cervical 3D time-of-flight magnetic resonance angiography. Fourteen patients had stenosis at enrollment, but only five SCT versus 10 standard-care patients still had stenosis at 3 years. Stenosis scores remained stable on standard-care, but significantly improved after SCT (P = 0·006). No patient developed stenosis after SCT, while two on standard-care did, indicating better stenosis prevention and improved outcome after SCT.

Burden of neurological and neurocognitive impairment in pediatric sickle cell anemia in Uganda (BRAIN SAFE): a cross-sectional study

Background

Children with sickle cell anemia (SCA) are highly susceptible to stroke and other manifestations of pediatric cerebral vasculopathy. Detailed evaluations in sub-Saharan Africa are limited.

Methods

We aimed to establish the frequency and types of pediatric brain injury in a cross-sectional study at a large SCA clinic in Kampala, Uganda in a randomly selected sample of 265 patients with HbSS ages 1–12 years. Brain injury was defined as one or more abnormality on standardized testing: neurocognitive impairment using an age-appropriate test battery, prior stroke by examination or transcranial Doppler (TCD) velocities associated with stroke risk in children with SCA (cerebral arterial time averaged mean maximum velocity ≥ 170 cm/second).

Results

Mean age was 5.5 ± 2.9 years; 52.3% were male. Mean hemoglobin was 7.3 ± 1.01 g/dl; 76.4% had hemoglobin < 8.0 g/dl. Using established international standards, 14.7% were malnourished, and was more common in children ages 5–12. Overall, 57 (21.5%) subjects had one to three abnormal primary testing. Neurocognitive dysfunction was found in 27, while prior stroke was detected in 15 (5.7%). The most frequent abnormality was elevated TCD velocity 43 (18.1%), of which five (2.1%) were in the highest velocity range of abnormal. Only impaired neurocognitive dysfunction increased with age (OR 1.44, 95%CI 1.23–1.68), p < 0.001). In univariate models, malnutrition defined as wasting (weight-for-height ≤ −2SD), but not sex or hemoglobin, was modestly related to elevated TCD (OR 1.37, 95%CI 1.01–1.86, p = 0.04). In adjusted models, neurocognitive dysfunction was strongly related to prior stroke (OR 6.88, 95%CI 1.95–24.3, p = .003) and to abnormal TCD (OR 4.37, 95%CI 1.30, p = 0.02). In a subset of 81 subjects who were enriched for other abnormal results, magnetic resonance imaging and angiography (MRI/MRA) detected infarcts and/or arterial stenosis in 52%. Thirteen subjects (25%) with abnormal imaging had no other abnormalities detected.

Conclusions

The high frequency of neurocognitive impairment or other abnormal results describes a large burden of pediatric SCA brain disease in Uganda. Evaluation by any single modality would have underestimated the impact of SCA. Testing the impact of hydroxyurea or other available disease-modifying interventions for reducing or preventing SCA brain effects is warranted.

Hematopoietic stem cell transplantation for sickle cell disease: Progress and challenges

Sickle cell disease (SCD) presents challenges to hematopoietic stem cell transplantation (HSCT), including donor availability and morbidity with age/disease severity. However, severe SCD causes irreversible organ damage that HSCT can mitigate. This benefit must be balanced against preparative regimen toxicity, graft-versus-host disease, and mortality risk. We review efforts to balance HSCT complications with the promise of cure, and knowledge gaps that warrant further investigation. We highlight the burden of SCD, HSCT risks and benefits, and SCD families' approach to this balance. We emphasize the necessity for information exchange to ensure a joint decision-making process between providers and patients.