Empirically derived profiles of neurocognitive functioning in youth and young adults with sickle cell disease.

OBJECTIVE: Sickle cell disease (SCD) is an inherited blood disorder associated with neurocognitive deficits. In contrast to variable-centered approaches, no known research has utilized person-centered strategies to identify multidimensional patterns of neurocognitive functioning of an individual with SCD. The purpose of the present study was to create empirically derived profiles and identify predictors of neurocognitive functioning subgroups among youth and young adults with SCD. METHODS: Individuals with SCD (N = 393, mean age 14.05 years, age range 8-24, 50.4% female/49.6% male) completed neurocognitive assessments. Latent profile analysis derived subgroups/classes of neurocognitive functioning and determined relations with demographic and medical variables. RESULTS: Three latent classes emerged: average functioning (n = 102, 27%), low average functioning (n = 225, 60%), and exceptionally low functioning (n = 46, 12%). Older age was associated with membership in the low average and exceptionally low functioning groups (relative to the average group). Being prescribed hydroxyurea was associated with membership in the average functioning group (relative to the low average group) and absence of hydroxyurea use was associated with membership in the exceptionally low group (relative to the low average group). Lower social vulnerability was associated with membership in the average functioning group compared to the low average and exceptionally low groups. CONCLUSIONS: Clinicians can help reduce disparities in cognitive development for individuals with SCD by promoting early treatment with hydroxyurea and implementing methods to reduce social vulnerabilities that can interfere with access to evidence-based care.

Recruitment Strategies in the Integration of Mobile Health Into Sickle Cell Disease Care to Increase Hydroxyurea Utilization Study (meSH): Multicenter Survey Study.

BACKGROUND: Hydroxyurea is an evidence-based disease-modifying therapy for sickle cell disease (SCD) but is underutilized. The Integration of Mobile Health into Sickle Cell Disease Care to Increase Hydroxyurea Utilization (meSH) multicenter study leveraged mHealth to deliver targeted interventions to patients and providers. SCD studies often underenroll; and recruitment strategies in the SCD population are not widely studied. Unanticipated events can negatively impact enrollment, making it important to study strategies that ensure adequate study accrual. OBJECTIVE: The goal of this study was to evaluate enrollment barriers and the impact of modified recruitment strategies among patients and providers in the meSH study in response to a global emergency. METHODS: Recruitment was anticipated to last 2 months for providers and 6 months for patients. The recruitment strategies used with patients and providers, new recruitment strategies, and recruitment rates were captured and compared. To document recruitment adaptations and their reasons, study staff responsible for recruitment completed an open-ended 9-item questionnaire eliciting challenges to recruitment and strategies used. Themes were extrapolated using thematic content analysis. RESULTS: Total enrollment across the 7 sites included 89 providers and 293 patients. The study acceptance rate was 85.5% (382/447) for both patients and providers. The reasons patients declined participation were most frequently a lack of time and interest in research, while providers mostly declined because of self-perceived high levels of SCD expertise, believing they did not need the intervention. Initially, recruitment involved an in-person invitation to participate during clinic visits (patients), staff meetings (providers), or within the office (providers). We identified several important recruitment challenges, including (1) lack of interest in research, (2) lack of human resources, (3) unavailable physical space for recruitment activities, and (4) lack of documentation to verify eligibility. Adaptive strategies were crucial to alleviate enrollment disruptions due to the COVID-19 pandemic. These included remote approaching and consenting (eg, telehealth, email, and telephone) for patients and providers. Additionally, for patients, recruitment was enriched by simplification of enrollment procedures (eg, directly approaching patients without a referral from the provider) and a multitouch method (ie, warm introductions with flyers, texts, and patient portal messages). We found that patient recruitment rates were similar between in-person and adapted (virtual with multitouch) approaches (167/200, 83.5% and 126/143, 88.1%, respectively; P=.23). However, for providers, recruitment was significantly higher for in-person vs remote recruitment (48/50, 96% and 41/54, 76%, respectively, P<.001). CONCLUSIONS: We found that timely adaptation in recruitment strategies secured high recruitment rates using an assortment of enriched remote recruitment strategies. Flexibility in approach and reducing the burden of enrollment procedures for participants aided enrollment. It is important to continue identifying effective recruitment strategies in studies involving patients with SCD and their providers and the impact and navigation of recruitment challenges. TRIAL REGISTRATION: ClinicalTrials.Gov NCT03380351; https://clinicaltrials.gov/study/NCT03380351. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.2196/16319.

Awareness, access, and communication: provider perspectives on early intervention services for children with sickle cell disease.

Purpose: This study aimed to identify determinants influencing the utilization of early intervention services among young children with sickle cell disease (SCD) based on perspectives from medical and early intervention providers. Design and methods: Early intervention and medical providers from the catchment area surrounding St. Jude Children's Research Hospital and Washington University were recruited (20 total providers). Interviews were completed over the phone and audio recorded. All interviews were transcribed verbatim, coded, and analyzed using inductive thematic analysis. Results: Three overarching themes were identified from both groups: Awareness (e.g., lack of awareness about the EI system and SCD), Access (e.g., difficulties accessing services), and Communication (e.g., limited communication between medical and early intervention providers, and between providers and families). Although these three themes were shared by medical and early intervention providers, the differing perspectives of each produced subthemes unique to the two professional fields. Conclusions: Early intervention services can limit the neurodevelopmental deficits experienced by young children with SCD; however, most children with SCD do not receive these services. The perspectives of early intervention and medical providers highlight several potential solutions to increase early intervention utilization among young children with SCD.

Machine learning to optimize automated RH genotyping using whole-exome sequencing data.

Rh phenotype matching reduces but does not eliminate alloimmunization in patients with sickle cell disease (SCD) due to RH genetic diversity that is not distinguishable by serological typing. RH genotype matching can potentially mitigate Rh alloimmunization, but comprehensive and accessible genotyping methods are needed. We developed RHtyper as an automated algorithm to predict RH genotypes using whole-genome sequencing (WGS) data with high accuracy. Here, we adapted RHtyper for whole-exome sequencing (WES) data which are more affordable but challenged by uneven sequencing coverage and exacerbated sequencing read misalignment, resulting in uncertain prediction for 1) RHD zygosity and hybrid alleles, 2) RHCE*C versus RHCE*c alleles, 3) RHD c.1136C>T zygosity, and 4) RHCE c.48G>C zygosity. We optimized RHtyper to accurately predict RHD and RHCE genotypes using WES data by leveraging machine learning models and improved the concordance of WES with WGS predictions from 90.8% to 97.2% for RHD and 96.3 to 98.2% for RHCE among 396 patients in the Sickle Cell Clinical Research and Intervention Program (SCCRIP). In a second validation cohort with 3030 cancer survivors (15.2% Black or African Americans) from the St. Jude Lifetime Cohort Study (SJLIFE), the optimized RHtyper reached concordance rates between WES and WGS predications to 96.3% for RHD, and 94.6% for RHCE. In conclusion, machine learning improved the accuracy of RH predication from WES data. RHtyper has the potential, once implemented, to provide a precision medicine-based approach to facilitate RH genotype-matched transfusion and improve transfusion safety for patients with SCD.

Mortality in adults with sickle cell disease: Results from the sickle cell disease implementation consortium (SCDIC) registry.

The cause of death in people affected by sickle cell disease (SCD) is often challenging to define as prior studies have used retrospective or administrative data for analysis. We used a prospective longitudinal registry to assess mortality and clinical co-morbidities among subjects enrolled in the Sickle Cell Disease Implementation Consortium (SCDIC) registry. At enrollment, we collected the following data: patient-reported demographics, SCD phenotype, baseline laboratory values, comorbidities, and current medications. Subjects were followed for a median of 4.7 years before the present analysis. The relationship of clinical co-morbidities (at time of enrollment) to mortality was determined using survival analysis, adjusting for SCD phenotype and gender. There was a total of 2439 people with SCD enrolled in the SCDIC registry. One hundred and twenty-eight participants (5%) died during the observation period (2017-2022). Six people died from trauma and were excluded from further analysis. Proximate cause of death was unwitnessed in 17% of the deaths, but commonest causes of death include cardiac (18%), acute chest or respiratory failure (11%), sudden unexplained death (8%). Enrollment characteristics of the individuals who died (n = 122) were compared to those of survivors (n = 2317). Several co-morbidities at enrollment increased the odds of death on univariate analysis. All co-morbidities were included in a multivariable model. After backward elimination, iron overload, pulmonary hypertension, and depression, remained statistically significant predictors of the risk of death. SCD reduces life expectancy. Improved comprehensive and supportive care to prevent end-organ damage and address comorbidities is needed for this population.

Description of a national, multi-center registry of patients with sickle cell disease and SARS-CoV-2 infection: Data from the Pediatric COVID-19 United States Registry.

Children with sickle cell disease (SCD) are at risk of complications from viral infections, including SARS-CoV-2. We present the clinical characteristics and outcomes of pediatric patients with SCD from the Pediatric COVID-19 United States Registry who developed acute COVID-19 due to SARS-CoV-2 infection (n = 259) or multisystem inflammatory syndrome in children (MIS-C; n = 4). Nearly half of hospitalized children with SCD and SARS-CoV-2 infection required supplemental oxygen, though children with SCD had fewer intensive care (ICU) admissions compared to the general pediatric and immunocompromised populations. All registry patients with both SCD and MIS-C required ICU admission. Children with SCD are at risk of severe disease with SARS-CoV-2 infection, highlighting the importance of vaccination in this vulnerable population.

RH genotypes and red cell alloimmunization rates in chronically transfused patients with sickle cell disease: A multisite study in the USA.

BACKGROUND: Red cell alloimmunization remains a challenge for individuals with sickle cell disease (SCD) and contributes to increased risk of hemolytic transfusion reactions and associated comorbidities. Despite prophylactic serological matching for ABO, Rh, and K, red cell alloimmunization persists, in part, due to a high frequency of variant RH alleles in patients with SCD and Black blood donors. STUDY DESIGN AND METHODS: We compared RH genotypes and rates of alloimmunization in 342 pediatric and young adult patients with SCD on chronic transfusion therapy exposed to >90,000 red cell units at five sites across the USA. Genotyping was performed with RHD and RHCE BeadChip arrays and targeted assays. RESULTS: Prevalence of overall and Rh-specific alloimmunization varied among institutions, ranging from 5% to 41% (p = .0035) and 5%-33% (p = .0002), respectively. RH genotyping demonstrated that 33% RHD and 57% RHCE alleles were variant in this cohort. Patients with RHCE alleles encoding partial e antigens had higher rates of anti-e identified than those encoding at least one conventional e antigen (p = .0007). There was no difference in anti-D, anti-C, or anti-E formation among patients with predicted partial or altered antigen expression compared to those with conventional antigens, suggesting that variant Rh on donor cells may also stimulate alloimmunization to these antigens. DISCUSSION: These results highlight variability in alloimmunization rates and suggest that a molecular approach to Rh antigen matching may be necessary for optimal prevention of alloimmunization given the high prevalence of variant RH alleles among both patients and Black donors.

Translation, transcultural adaptation, and validation of PedsQL 3.0 Sickle Cell Disease Module into Brazilian Portuguese.

INTRODUCTION: Despite the high prevalence of sickle cell disease (SCD) in Brazil, no studies have described the validation of an SCD-specific health-related quality-of-life (HRQoL) instrument in children. We validated PedsQL 3.0 Sickle Cell Disease Module (PedsQL-SCD) for Brazilian Portuguese, and cross-validated it with PedsQL 4.0 Generic Core Scale (PedsQL-GCS) in children with SCD. METHODS: PedsQL-SCD was translated and culturally adapted using forward and reverse translations. PedsQL-SCD and PedsQL-GCS were tested in children and adolescents with SCD aged 2-18 years and their caregivers. Validity was assessed using the Pearson and intraclass correlation coefficients, and reliability measured with Cronbach's alpha. RESULTS: PedsQL-SCD was validated in 206 children with SCD (median age 14 years, range: 8-18) and 201 caregivers. Among patients and caregivers, the mean total score for PedsQL-SCD was 65.7 and 64.1, respectively. The mean total score for PedsQL-GCS was 73.1 and 68.9 among patients and caregivers, respectively. The internal consistency for PedsQL-SCD and PedsQL-GCS was good; Cronbach's alpha coefficients ranged from .59-.93 to .64-.83 among patients and from .60-.95 to .65-.85 among caregivers, respectively. Most intercorrelations between PedsQL-SCD and PedsQL-GCS, for patients and caregivers, had medium to large effect sizes (range: .23-.63 and .27-.64, respectively). Pain and pain impact domains of PedsQL-SCD and physical dimension of PedsQL-GCS had the highest cross-correlation (.63 and .6 for patients; .63 and .64 for caregivers, respectively), confirming convergent construct validity. CONCLUSION: PedsQL-SCD is a valid, culturally appropriate measure to assess HRQoL in children with SCD in Brazil and is well-correlated PedsQL-GCS.

Burden of employment loss and absenteeism in adults and caregivers of children with sickle cell disease.

ABSTRACT: Sickle cell disease (SCD) is a genetic disorder affecting 100 000 people with an estimated annual medical cost of $3 billion in the United States; however, the economic impact on patients is not well described. We aimed to examine the indirect economic burden and test the hypothesis that socioeconomic status and greater social vulnerability risks are associated with increased absenteeism and employment loss. We surveyed adults and caregivers of children with SCD at 5 US centers from 2014 to 2021. Logistic regression models were used to examine the associations of employment loss and missed days of work with demographics and social determinants. Indirect costs were estimated by multiplying the self-reported missed days of work and job loss by 2022 average wages by the state of the participating institution. Of the 244 participants, 10.3% reported employment loss in the last 5 years, and 17.5% reported missing 10 or more days of work. Adults had 3 times more employment loss compared with caregivers of children with SCD (OR, 3.18; 95% CI, 1.12-9.01) but fewer missed days of work (OR, 0.24; 95% CI, 0.11-0.0.51). Participants who did not live with a partner reported increased employment loss (OR, 4.70; 95% CI, 1.04-21.17) and more missed days of work (OR, 4.58; 95% CI, 1.04-20.15). The estimated annual indirect economic burden was $2 266 873 ($9290 per participant). Adults with SCD and caregivers of children with SCD commonly report employment loss and missed days of work as important risk factors. The high indirect economic burden suggests that future economic evaluations of SCD should include SCD-related indirect economic burden.

Gene Therapy Versus Common Care for Eligible Individuals With Sickle Cell Disease in the United States : A Cost-Effectiveness Analysis.

BACKGROUND: Sickle cell disease (SCD) and its complications contribute to high rates of morbidity and early mortality and high cost in the United States and African heritage community. OBJECTIVE: To evaluate the cost-effectiveness of gene therapy for SCD and its value-based prices (VBPs). DESIGN: Comparative modeling analysis across 2 independently developed simulation models (University of Washington Model for Economic Analysis of Sickle Cell Cure [UW-MEASURE] and Fred Hutchinson Institute Sickle Cell Disease Outcomes Research and Economics Model [FH-HISCORE]) using the same databases. DATA SOURCES: Centers for Medicare & Medicaid Services claims data, 2008 to 2016; published literature. TARGET POPULATION: Persons eligible for gene therapy. TIME HORIZON: Lifetime. PERSPECTIVE: U.S. health care sector and societal. INTERVENTION: Gene therapy versus common care. OUTCOME MEASURES: Incremental cost-effectiveness ratios (ICERs), equity-informed VBPs, and price acceptability curves. RESULTS OF BASE-CASE ANALYSIS: At an assumed $2 million price for gene therapy, UW-MEASURE and FH-HISCORE estimated ICERs of $193 000 per QALY and $427 000 per QALY, respectively, under the health care sector perspective. Corresponding estimates from the societal perspective were $126 000 per QALY and $281 000 per QALY. The difference in results between models stemmed primarily from considering a slightly different target population and incorporating the quality-of-life (QOL) effects of splenic sequestration, priapism, and acute chest syndrome in the UW model. From a societal perspective, acceptable (>90% confidence) VBPs ranged from $1 million to $2.5 million depending on the use of alternative effective metrics or equity-informed threshold values. RESULTS OF SENSITIVITY ANALYSIS: Results were sensitive to the costs of myeloablative conditioning before gene therapy, effect on caregiver QOL, and effect of gene therapy on long-term survival. LIMITATION: The short-term effects of gene therapy on vaso-occlusive events were extrapolated from 1 study. CONCLUSION: Gene therapy for SCD below a $2 million price tag is likely to be cost-effective when applying a societal perspective at an equity-informed threshold for cost-effectiveness analysis. PRIMARY FUNDING SOURCE: National Heart, Lung, and Blood Institute.

Comparative pharmacovigilance assessment of adverse events associated with the use of hydroxyurea, L-glutamine, voxelotor, and crizanlizumab in sickle cell disease.

Using disproportionality analysis, this study compared the adverse events (AEs) associated with the use of the new agents (e.g., L-glutamine, voxelotor, and crizanlizumab) to the commonly used medication, hydroxyurea, in sickle cell disease. We found that the most frequent drug-related AEs observed in this real-world study were consistent with those in the HOPE (voxelotor) and SUSTAIN (crizanlizumab) trials, but the rates of AEs were lower. Our study demonstrates that the most common AEs and symptoms of an increased risk associated with the individual drugs varied by treatment. Disproportionate reporting signals of drug-related AEs may also capture information that is independent of subjective measures of patient-reported symptoms. Our study highlights the important need for facilitating patient-physician communication in routine clinical care to understand patient-reported symptoms.

Agreement between youth and caregiver report of pain and functioning in pediatric sickle cell disease: PedsQL sickle cell disease module.

ABSTRACT: Pain is a primary symptom of sickle cell disease (SCD) and is often severe and chronic. To treat SCD-related pain, proper assessment of SCD pain among youth, including the degree of concordance or agreement between youth and caregiver reports of pain, is essential but has not yet been adequately evaluated. In this study, 525 youth with SCD and their parents were evaluated as part of the Sickle Cell Clinical Research and Intervention Program (SCCRIP) to examine pain rating concordance and predictors of concordance. Youth and parents completed the Pediatric Quality of Life Inventory Sickle Cell Disease module (PedsQL-SCD) to measure pain, pain interference, and pain-related constructs. Disease, clinical, and demographic variables were obtained from the SCCRIP database. Intraclass correlations demonstrated moderate-to-poor consistency between youth and caregiver reports of pain and pain interference (ICCs range from 0.17 to 0.54). Analysis of covariance and regression models found that patient age, frequency of hospitalizations and emergency department (ED) visits, economic hardship, and fetal hemoglobin levels were significantly associated with varying pain-rating agreement levels among parent proxy and child self-report pain. Concordance of pain assessments among youth with SCD and their caregivers using the PedsQL-SCD Module was moderate at best, corroborating prior research. Youth factors predicting discordance among pain-related factors included increased ED visits, older age, and female sex. Collectively, these results bolster the use of integrated pain assessments to reduce parent-child discrepancies, thereby improving the adequacy of SCD-related pain assessment and treatment.

Multicomponent Strategy Improves Human Papillomavirus Vaccination Rates Among Adolescents with Sickle Cell Disease.

OBJECTIVE: To evaluate the effectiveness of a vaccine strategy bundle to increase human papillomavirus (HPV) vaccine initiation and completion in a specialty clinic setting. STUDY DESIGN: Our Hematology clinic utilized an implementation framework from October 1, 2018, to December 31, 2019, involving nurses, nursing coordinators, and clinicians in administering the HPV vaccination series to our adolescent sickle cell sample of nearly 500 patients. The bundle included education for staff on the need for HPV vaccine administration, provider incentives, vaccines offered to patients in SCD clinics, and verification of patients' charts of vaccine completion. RESULTS: Following the implementation of the bundle, the cumulative incidence of HPV vaccination initiation and completion improved from 28% to 46% and 7% to 49%, respectively. Both rates remained higher postimplementation as well. HPV vaccination series completion was associated with a decreased distance to the health care facility, lower state deprivation rank, and increased hospitalizations. CONCLUSION: Our clinic's implementation strategy successfully improved vaccine completion rates among adolescents with sickle cell disease (SCD) while continuing to educate staff, patients, and families on the importance of cancer prevention among people living with SCD.

Corrigendum: Academic performance of children with sickle cell disease in the United States: a meta-analysis.

[This corrects the article DOI: 10.3389/fneur.2021.786065.].

"The project did not come to us with a solution": Perspectives of research teams on implementing a study about electronic health record-embedded individualized pain plans for emergency department treatment of vaso-occlusive episodes in adults with sickle cell disease.

BACKGROUND: This study aimed to capture the implementation process of the ALIGN Study, (An individualized Pain Plan with Patient and Provider Access for Emergency Department care of Sickle Cell Disease). ALIGN aimed to embed Individualized Pain Plans in the electronic health record (E-IPP) and provide access to the plan for both adult patients with sickle cell disease (SCD) and emergency department providers when a person with SCD comes to the emergency department in vaso-occlusive crises. METHODS: Semi-structured interviews were conducted with research teams from the 8 participating sites from the ALIGN study. Seventeen participants (principal investigators and study coordinators) shared their perspectives about the implementation of ALIGN in their sites. Data were analyzed in three phases using open coding steps adapted from grounded theory and qualitative content analysis. RESULTS: A total of seven overarching themes were identified: (1) the E-IPP structure (location and upkeep) and collaboration with the informatics team, (2) the role of ED champion, (3) the role of research coordinators, (4) research team communication, and communication between research team and clinical team, (5) challenges with the study protocol, (6) provider feedback: addressing over-utilizers, patient mistrust, and the positive feedback about the intervention, and (7) COVID-19 and its effects on study implementation. CONCLUSIONS: Findings from this study contribute to learning how to implement E-IPPs for adult patients with SCD in ED. The study findings highlight the importance of early engagement with different team members, a champion from the emergency department, study coordinators with different skills and enhancement of communication and trust among team members. Further recommendations are outlined for hospitals aiming to implement E-IPP for patients with SCD in ED.

Provider prescription of hydroxyurea in youth and adults with sickle cell disease: A review of prescription barriers and facilitators.

Sickle cell disease (SCD) is an inherited red blood cell disorder associated with frequent painful events and organ damage. Hydroxyurea (HU) is the recommended evidence-based treatment of SCD. However, among patients eligible for HU, prescription rates are low. Utilizing a scoping review approach, we summarized and synthesized relevant findings regarding provider barriers and facilitators to the prescription of HU in youth and adults with SCD and provided suggestions for future implementation strategies to improve prescription rates. Relevant databases were searched using specified search terms. Articles reporting provider barriers and/or facilitators to prescribing HU were included. A total of 10 studies met the inclusion criteria. Common barriers to the prescription of HU identified by providers included: doubts around patients' adherence to HU and their engaging in required testing, concerns about side effects, lack of knowledge, cost and patient concerns about side effects. Facilitators to the prescription of HU included beliefs in the effectiveness of HU, provider demographics and knowledge. Findings suggest significant provider biases exist, particularly in the form of negative perceptions towards patients' ability to adhere to taking HU and engaging in the required follow-up. Improving provider knowledge and attitudes towards HU and SCD may help improve low prescription rates.

A multilevel mHealth intervention boosts adherence to hydroxyurea in individuals with sickle cell disease.

Hydroxyurea reduces sickle cell disease (SCD) complications, but medication adherence is low. We tested 2 mobile health (mHealth) interventions targeting determinants of low adherence among patients (InCharge Health) and low prescribing among providers (HU Toolbox) in a multi-center, non-randomized trial of individuals with SCD ages 15-45. We compared the percentage of days covered (PDC), labs, healthcare utilization, and self-reported pain over 24 weeks of intervention and 12 weeks post-study with a 24-week preintervention interval. We enrolled 293 patients (51% male; median age 27.5 years, 86.8% HbSS/HbSß0-thalassemia). The mean change in PDC among 235 evaluable subjects increased (39.7% to 56.0%; P < 0.001) and sustained (39.7% to 51.4%, P < 0.001). Mean HbF increased (10.95% to 12.78%; P = 0.03). Self-reported pain frequency reduced (3.54 to 3.35 events/year; P = 0.041). InCharge Health was used ≥1 day by 199 of 235 participants (84.7% implementation; median usage: 17% study days; IQR: 4.8-45.8%). For individuals with ≥1 baseline admission for pain, admissions per 24 weeks declined from baseline through 24 weeks (1.97 to 1.48 events/patient, P = 0.0045) and weeks 25-36 (1.25 events/patient, P = 0.0015). PDC increased with app use (P < 0.001), with the greatest effect in those with private insurance (P = 0.0078), older subjects (P = 0.033), and those with lower pain interference (P = 0.0012). Of the 89 providers (49 hematologists, 36 advanced care providers, 4 unreported), only 11.2% used HU Toolbox ≥1/month on average. This use did not affect change in PDC. Tailoring mHealth solutions to address barriers to hydroxyurea adherence can potentially improve adherence and provide clinical benefits. A definitive randomized study is warranted. This trial was registered at www.clinicaltrials.gov as #NCT04080167.

CRISPR-Cas9 Editing of the HBG1 and HBG2 Promoters to Treat Sickle Cell Disease.

BACKGROUND: Sickle cell disease is caused by a defect in the ß-globin subunit of adult hemoglobin. Sickle hemoglobin polymerizes under hypoxic conditions, producing deformed red cells that hemolyze and cause vaso-occlusion that results in progressive organ damage and early death. Elevated fetal hemoglobin levels in red cells protect against complications of sickle cell disease. OTQ923, a clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9-edited CD34+ hematopoietic stem- and progenitor-cell (HSPC) product, has a targeted disruption of the HBG1 and HBG2 (γ-globin) gene promoters that increases fetal hemoglobin expression in red-cell progeny. METHODS: We performed a tiling CRISPR-Cas9 screen of the HBG1 and HBG2 promoters by electroporating CD34+ cells obtained from healthy donors with Cas9 complexed with one of 72 guide RNAs, and we assessed the fraction of fetal hemoglobin-immunostaining erythroblasts (F cells) in erythroid-differentiated progeny. The gRNA resulting in the highest level of F cells (gRNA-68) was selected for clinical development. We enrolled participants with severe sickle cell disease in a multicenter, phase 1-2 clinical study to assess the safety and adverse-effect profile of OTQ923. RESULTS: In preclinical experiments, CD34+ HSPCs (obtained from healthy donors and persons with sickle cell disease) edited with CRISPR-Cas9 and gRNA-68 had sustained on-target editing with no off-target mutations and produced high levels of fetal hemoglobin after in vitro differentiation or xenotransplantation into immunodeficient mice. In the study, three participants received autologous OTQ923 after myeloablative conditioning and were followed for 6 to 18 months. At the end of the follow-up period, all the participants had engraftment and stable induction of fetal hemoglobin (fetal hemoglobin as a percentage of total hemoglobin, 19.0 to 26.8%), with fetal hemoglobin broadly distributed in red cells (F cells as a percentage of red cells, 69.7 to 87.8%). Manifestations of sickle cell disease decreased during the follow-up period. CONCLUSIONS: CRISPR-Cas9 disruption of the HBG1 and HBG2 gene promoters was an effective strategy for induction of fetal hemoglobin. Infusion of autologous OTQ923 into three participants with severe sickle cell disease resulted in sustained induction of red-cell fetal hemoglobin and clinical improvement in disease severity. (Funded by Novartis Pharmaceuticals; ClinicalTrials.gov number, NCT04443907.).