Decreased fetal hemoglobin over time among youth with sickle cell disease on hydroxyurea is associated with higher urgent hospital use

Hydroxyurea Adherence for Personal Best in Sickle Cell Treatment (HABIT) efficacy trial: Community health worker support may increase hydroxyurea adherence of youth with sickle cell disease

Despite disease-modifying effects of hydroxyurea on sickle cell disease (SCD), poor adherence among affected youth commonly impedes treatment impact. Following our prior feasibility trial, the "Hydroxyurea Adherence for Personal Best in Sickle Cell Treatment (HABIT)" multi-site randomized controlled efficacy trial aimed to increase hydroxyurea adherence for youth with SCD ages 10-18 years. Impaired adherence was identified primarily through flagging hydroxyurea-induced fetal hemoglobin (HbF) levels compared to prior highest treatment-related HbF. Eligible youth were enrolled as dyads with their primary caregivers for the 1-year trial. This novel semi-structured supportive, multidimensional dyad intervention led by community health workers (CHW), was augmented by daily tailored text message reminders, compared to standard care during a 6-month intervention phase, followed by a 6-month sustainability phase. Primary outcomes from the intervention phase were improved Month 6 HbF levels compared to enrollment and proportion of days covered (PDC) for hydroxyurea versus pre-trial year. The secondary outcome was sustainability of changes up to Month 12. The 2020-2021 peak coronavirus disease 2019 (COVID-19) pandemic disrupted enrollment and clinic-based procedures; CHW in-person visits shifted to virtual scheduled interactions. We enrolled 50 dyads, missing target enrollment. Compared to enrollment levels, both HbF level and PDC significantly - but not sustainably - improved within the intervention group (p = .03 and .01, respectively) with parallel increased mean corpuscular volume (MCV) (p = .05), but not within controls. No significant between-group differences were found at Months 6 or 12. These findings suggest that our community-based, multimodal support for youth-caregiver dyads had temporarily improved hydroxyurea usage. Durability of impact should be tested in a trial with longer duration of CHW-led and mobile health support.

Health-Related Quality of Life and Adherence to Hydroxyurea and Other Disease-Modifying Therapies among Individuals with Sickle Cell Disease: A Systematic Review

Background

Sickle cell disease (SCD) is a hemoglobinopathy with increasing global prevalence resulting in pain episodes and multiorgan complications. Complications of SCD have been shown to adversely impact health-related quality of life (HRQOL) comprised of physical, social, and emotional domains; hence, HRQOL measures can serve as an effective evaluator of disease burden. Hydroxyurea (HU) and other disease-modifying therapies have demonstrated to significantly improve clinical outcomes in patients with SCD. Medication adherence is an essential mediator of the clinical benefits of these therapies; low adherence has been shown to increase disease burden and healthcare utilization. This systematic literature review intends to determine the association between adherence to disease-modifying therapies and HRQOL in patients with SCD.

Methods

We found a total of 12 articles involving 788 participants, which included both patients with SCD and caregivers/parents. Adherence was measured using self-report instruments, laboratory markers, such as fetal hemoglobin and mean corpuscular volume, and mHealth medication trackers. HRQOL was measured using self-report instruments.

Results

All studies demonstrated a correlation between higher HU adherence and better HRQOL scores. Higher HU adherence was associated with lower pain impact, less frequent pain episodes, less fatigue, and improved physical function and mobility, reflecting better physical HRQOL outcomes. Higher adherence was also associated with improved emotional response, decreased anxiety and depressive symptoms, and better social functioning and peer relationships. In addition, our findings indicated that having less frequent barriers to HU adherence was associated with better HRQOL scores. No studies evaluated HRQOL outcomes in relation to adherence to l-glutamine, voxelotor, or crizanlizumab.

Conclusions

Optimizing HU adherence has the potential to improve HRQOL in patients with SCD in addition to reducing healthcare utilization and improving treatment satisfaction. Addressing barriers to HU adherence can positively strengthen the relationship between adherence and HRQOL to potentially improve patient outcomes.

Hydroxyurea Decouples Persistent F-Cell Elevation and Induction of γ-Globin

Mechanisms that control the fetal-to-adult hemoglobin switch are attractive therapeutic targets in sickle cell disease. In this study, we investigated developmental γ-globin silencing in the Townes humanized knock-in mouse model, which harbors a construct containing the human γ-, β^A-, and β^S-globin genes, and examined the utility of this model in evaluation of pharmacologic induction of fetal hemoglobin (HbF). We studied mouse pups on the day of delivery (P0) to 28 days after birth (P28). Regardless of the hemoglobin genotype (SS, AS, or AA), the proportion of F cells in peripheral blood was 100% at P0, declined sharply to 20% at P2, and was virtually undetectable at P14. Developmental γ-globin silencing in Townes mice was complete at P4 in association with significantly increased BCL11A expression in the primary erythropoietic organs of the mouse. Hydroxyurea given at P2 significantly sustained elevated percentages of F cells in mice at P14. However, the percentage of F cells declined at P14 for treatment begun at P4. A lack of augmentation of γ-globin mRNA in erythroid tissues suggests that the apparent increase in HbF in red cells caused by hydroxyurea was not due to sustained or re-activation of γ-globin transcription, but was instead a function of erythropoiesis suppression. Thus, we provide new details of the hemoglobin switch in the Townes murine model that recapitulates postnatal γ- to β-globin switch in humans and identify the myelosuppressive toxicity of hydroxyurea as a superseding factor in interpreting pharmacologic induction of HbF.

Ten-year Longitudinal Analysis of Hydroxyurea Implementation in a Pediatric Sickle Cell Program

Hydroxyurea (HU) has proven benefit in sickle cell anemia (SCA), but HU is still underutilized. The Pediatric Sickle Cell Program of Northern Virginia prescribes HU regardless of symptoms to all SCA patients age ≥ 9 months and prospectively tracks outcomes. HU is dosed to maximum tolerated dosing (MTD), targeting 30% Hgb F. Longitudinal data from 2009-2019 encompassing 1222 HU-eligible and 950 HU-exposure patient-years were analyzed in 2-year intervals for hemoglobin (Hgb), fetal hemoglobin (Hgb F), hospitalizations, transfusions, and treat-and-release ED visits. Comparing HU-eligible patients in the interval prior to HU implementation (2009-2011) to the last interval analyzed after HU implementation (2017-2019), HU usage increased from 33% to 93%, average Hgb increased from 8.3±0.98 to 9.8±1.3 g/dL (p<0.0001), average Hgb F rose from 13±8.7% to 26±9.9% (p<0.0001), hospitalizations decreased from 0.71 (95% CI 0.54-0.91) to 0.2 (95% CI 0.13-0.28) admissions/person-year, sporadic transfusions decreased from 0.4 (95% CI 0.27-0.55) to 0.05 (95% CI 0.02-0.12) transfusions/person-year. Treat-and-release ED visit rates remained unchanged, varying between 0.49 (95% CI 0.36-0.64) and 0.64 (95% CI 0.48-0.83) visits/person-year. By the last interval, 72% of patients had Hgb ≥ 9g/dL, 42% had Hgb F ≥ 30%, 79% experienced no hospitalizations, and 94% received no transfusions. Uniform HU prescription for SCA patients with close monitoring to achieve high Hgb F resulted in significant improvements in laboratory and clinical outcomes within 2 years, which continued to improve over the next 6 years. Rigorous HU implementation in a pediatric sickle cell population is feasible, effective, and sustainable. This article is protected by copyright. All rights reserved.

Pharmacological Induction of Fetal Hemoglobin in β-Thalassemia and Sickle Cell Disease: An Updated Perspective

A significant amount of attention has recently been devoted to the mechanisms involved in hemoglobin (Hb) switching, as it has previously been established that the induction of fetal hemoglobin (HbF) production in significant amounts can reduce the severity of the clinical course in diseases such as β-thalassemia and sickle cell disease (SCD). While the induction of HbF using lentiviral and genome-editing strategies has been made possible, they present limitations. Meanwhile, progress in the use of pharmacologic agents for HbF induction and the identification of novel HbF-inducing strategies has been made possible as a result of a better understanding of γ-globin regulation. In this review, we will provide an update on all current pharmacological inducer agents of HbF in β-thalassemia and SCD in addition to the ongoing research into other novel, and potentially therapeutic, HbF-inducing agents.

Transition Navigator Intervention Improves Transition Readiness to Adult Care for Youth With Sickle Cell Disease

OBJECTIVE

Adolescents and young adults (AYA) with sickle cell disease (SCD) experience high rates of acute care utilization and increased morbidity. At this high-risk time, they also face the need to transition from pediatric to adult services, which, if poorly coordinated, adds to heightened morbidity and acute care utilization. The study objective was to characterize the feasibility, acceptability, and short-term efficacy of a protocolized transition navigator (TN) intervention in AYA with SCD.

METHODS

We developed a protocolized TN intervention that used ecological assessment and motivational interviewing to assess transition readiness, identify goals, and remove barriers to transition, and to provide disease and pain management education and skills to AYAs with SCD.

RESULTS

Ninety-three percent (56/60) of enrolled individuals completed the intervention. Participation in the TN program was associated with significant improvement in mean transition readiness scores (3.58-4.15, P < .0001), disease knowledge scale (8.91-10.13, P < .0001), Adolescent Medication Barriers Scale (40.05-35.39, P = .003) and confidence in both disease (22.5-23.96, P = .048) and pain management (25.07-26.61, P = .003) for youth with SCD.

CONCLUSION

The TN intervention was acceptable to youth with SCD, feasible to implement at an urban academic medical center, and addressed barriers to transition identified by the youth. Longer-term assessment is needed to determine if the TN intervention improved successful transfer to and retention in adult care.

Impact of telehealth visits on hydroxyurea response in sickle cell anemia

BACKGROUND

It is important to ensure access to hydroxyurea (HU) for patients with sickle cell anemia (SCA) living in rural areas. The University of Alabama at Birmingham (UAB) Pediatric Sickle Cell program's satellite clinics reduce the barrier of transportation to the university-based clinic. However, as compared with the university clinic, these satellite clinics do not offer immediate access to HU dosing laboratory results and a nurse clinician calls families with HU dose adjustments after the clinic visit. This study evaluated the impact of telehealth dosing adjustments on HU laboratory and clinical response as compared with university-based patients.

METHODS

A one-year retrospective chart review was performed to evaluate HU laboratory and clinical response based on clinic location and socioeconomic status for patients with SCA. We identified the number of clinic and acute care visits for one year and calculated the mean complete blood count and fetal hemoglobin (HbF) values for each patient.

RESULTS

We identified 107 academic center participants with SCA-prescribed HU and 65 satellite clinic participants. The mean age of participants was 11 ± 5 years. We identified no difference in HbF (13.3 ± 0.7 vs 11.7 ± 0.8, P = 0.13), Hb (8.46 ± 1.1 vs 8.55 ± 1.1, P = 0.59), mean corpuscular volume (91.0 ± 10.6 vs 91.7 ± 9.5, P = 0.67), or absolute neutrophil count (4.85 ± 2.3 vs 4.87 ± 2.3, P = 0.95) when comparing Birmingham versus satellite clinics. We also identified no difference in hospital admissions (0.99 ± 0.1 versus 0.85 ± 0.2, P = 0.49), based on clinic location.

CONCLUSIONS

The use of telehealth did not negatively impact laboratory response to HU. Future studies should identify novel approaches to improve access to HU among patients with SCA living in rural areas.

Age-related healthcare services utilization for the management of sickle cell disease among treated Texas Medicaid patients

Objectives

To determine if there are age-related differences in sickle cell disease (SCD)-related healthcare utilization and to describe temporal healthcare utilization following an emergency department (ED) visit or hospitalization in treated SCD patient population.

Methods

Texas Medicaid prescription and medical claims from 1 September 2011 to 31 August 2016 were used. Patients aged 2–63 years with at least one inpatient or outpatient SCD medical claim and receiving one or more SCD-related medications (hydroxyurea, opioid or non-opioid analgesics) were included. The primary outcomes were utilization of SCD-related ED, inpatient and outpatient visits, all-cause prescription medications and type of SCD-related service at index and subsequent healthcare services. Age group was the primary independent variable.

Key findings

Overall (N = 2339), healthcare service utilization was relatively higher among age groups 2–12, 18–25 and 26–40. Proportions of patients having ≥1 ED and ≥1 inpatient visits, respectively, were significantly higher among age groups 2–12 (33.2%; 23.0%), 18–25 (29.3%; 25.1%) and 26–40 (32.3%; 22.4%) as compared with age group 13–17 (21.3%; 12.9%). The number of outpatient visits was highest among children aged 2–12 (4.5 ± 7.6, P &lt; 0.0001), while mean number of all-cause medications was the highest for older adults aged 41–63 (22.4 ± 16.3; P &lt; 0.0001). After an index ED visit (N = 598), outpatient visits were the most prevalent healthcare services. After an index hospitalization (N = 203), a subsequent hospitalization was the most prevalent healthcare service.

Conclusions

Texas Medicaid SCD patients receiving treatment have a high use of healthcare services, especially among children and young adults who are transitioning from childhood to adulthood. Age-specific interventions should be developed to promote optimal care transitions among young adults.

End points for sickle cell disease clinical trials: renal and cardiopulmonary, cure, and low-resource settings

To address the global burden of sickle cell disease and the need for novel therapies, the American Society of Hematology partnered with the US Food and Drug Administration to engage the work of 7 panels of clinicians, investigators, and patients to develop consensus recommendations for clinical trial end points. The panels conducted their work through literature reviews, assessment of available evidence, and expert judgment focusing on end points related to patient-reported outcome, pain (non-patient-reported outcomes), the brain, end-organ considerations, biomarkers, measurement of cure, and low-resource settings. This article presents the findings and recommendations of the end-organ considerations, measurement of cure, and low-resource settings panels as well as relevant findings and recommendations from the biomarkers panel.

Measuring hydroxyurea adherence by pharmacy and laboratory data compared with video observation in children with sickle cell disease

BACKGROUND

Hydroxyurea nonadherence is common among children with sickle cell disease (SCD), but it is unclear if current adherence measures are valid compared with video directly observed therapy (VDOT), a reference method. The objectives were to evaluate if hydroxyurea adherence by pharmacy records, urine assay, mean corpuscular volume (MCV), and/or fetal hemoglobin (HbF) correlated with and was sensitive and specific compared with VDOT.

METHODS

This was a cross-sectional analysis of adherence data from 34 children with SCD on a single-arm, six-month hydroxyurea adherence study. Spearman correlation coefficient compared participants' adherence by pharmacy records, MCV, and HbF to adherence by VDOT. The sensitivity and specificity of ≥80% adherence by pharmacy records, two urine samples with hydroxyurea, MCV ≥100 fl/L, and HbF ≥20% compared with ≥80% VDOT adherence were also calculated.

RESULTS

Median pharmacy and VDOT adherence rates were similar (87.8% vs 88.1%, P = 0.75) and mildly correlated (r_s  = 0.45; P = 0.008) but the sensitivity of ≥80% adherence by pharmacy records was 72.7% and specificity was 45.5%. MCV (r_s  = -0.02, P = 0.92) and HbF (r_s  = -0.2, P = 0.33) did not significantly correlate with VDOT adherence. Sensitivity and specificity were 83.3% and 33.3% for having two urine samples with hydroxyurea, 35% and 71.4% for MCV ≥100 fl/L, and 75% and 0% for HbF ≥20%, respectively.

CONCLUSIONS

Commonly used tools to measure hydroxyurea adherence may not correlate with or be valid compared with video adherence. Future studies to refine these measures are needed to effectively target adherence interventions to children with SCD who have the potential to benefit. (ClinicalTrials.gov NCT02578017).

Small molecule therapeutics to treat the β-globinopathies

PURPOSE OF REVIEW

The current review focuses on recent insights into the development of small molecule therapeutics to treat the β-globinopathies.

RECENT FINDINGS

Recent studies of fetal γ-globin gene regulation reveal multiple insights into how γ-globin gene reactivation may lead to novel treatment for β-globinopathies.

SUMMARY

We summarize current information regarding the binding of transcription factors that appear to be impeded or augmented by different hereditary persistence of fetal hemoglobin (HPFH) mutations. As transcription factors have historically proven to be difficult to target for therapeutic purposes, we next address the contributions of protein complexes associated with these HPFH mutation-affected transcription factors with the aim of defining proteins that might provide additional targets for chemical molecules to inactivate the corepressors. Among the enzymes associated with the transcription factor complexes, a group of corepressors with currently available inhibitors were initially thought to be good candidates for potential therapeutic purposes. We discuss possibilities for pharmacological inhibition of these corepressor enzymes that might significantly reactivate fetal γ-globin gene expression. Finally, we summarize the current clinical trial data regarding the inhibition of select corepressor proteins for the treatment of sickle cell disease and β-thalassemia.

HABIT efficacy and sustainability trial, a multi-center randomized controlled trial to improve hydroxyurea adherence in youth with sickle cell disease: a study protocol

Background

Hydroxyurea (HU) is recommended as standard practice for youth with sickle cell disease (SCD). Yet, despite its efficacy, HU adherence in adolescents and young adults is often poor. Poor medication adherence increases disease burden, healthcare cost and widens health disparities. Adolescence is a critical time to improve adherence through improved chronic disease self-management. This study aims to test the efficacy of an intervention delivered to youth/parent dyads by community health workers (CHWs), augmented by tailored text messages on HU adherence (primary outcome). Secondary outcomes are intervention sustainability, youth health-related quality of life, self-management responsibility concordance, acute hospital use and self-reported disease symptoms.

Methods

Hydroxyurea Adherence for Personal Best in Sickle Cell Disease, “HABIT,” is a 12 month multi-center randomized controlled trial. One hundred four youth, 10 to 18 years of age prescribed HU who meet eligibility criteria, enrolled with their parent as dyads, will be randomized 1:1 to either the HABIT intervention or to usual clinical care plus education handouts. All subjects will complete clinic visits at months 0, 2, 4, 6 (efficacy component), 9 and 12 (sustainability component) for assessment of HbF biomarker, other hematologic parameters, and to complete questionnaires. In addition, dyads assigned to the HABIT intervention will work with CHWs to identify a daily habit (e.g., brushing teeth) on which to build a HU adherence habit. Tailored daily text message reminders to support the habit will be developed by the dyad in collaboration with the CHWs and sent to parent and youth. At the 6 month visit, the intervention will end and the sustainability portion of the trial will begin. All data analyses will be based on intention to treat with all randomized subjects included in the analyses.

Discussion

Prior retrospective studies demonstrate that a majority of adolescents are poorly adherent to HU. If efficacious, the HABIT intervention has the potential to improve the lives of youth with SCD.

Trial registration

Clinicaltrials.gov NCT03462511. Registered March 6, 2018, last updated July 26, 2019.

Targeting sickle cell disease root-cause pathophysiology with small molecules

The complex, frequently devastating, multi-organ pathophysiology of sickle cell disease has a single root cause: polymerization of deoxygenated sickle hemoglobin. A logical approach to disease modification is, therefore, to interdict this root cause. Ideally, such interdiction would utilize small molecules that are practical and accessible for worldwide application. Two types of such small molecule strategies are actively being evaluated in the clinic. The first strategy intends to shift red blood cell precursor hemoglobin manufacturing away from sickle hemoglobin and towards fetal hemoglobin, which inhibits sickle hemoglobin polymerization by a number of mechanisms. The second strategy intends to chemically modify sickle hemoglobin directly in order to inhibit its polymerization. Important lessons have been learnt from the pre-clinical and clinical evaluations to date. Open questions remain, but this review summarizes the valuable experience and knowledge already gained, which can guide ongoing and future efforts for molecular mechanism-based, practical and accessible disease modification of sickle cell disease.

Greater number of perceived barriers to hydroxyurea associated with poorer health-related quality of life in youth with sickle cell disease

BACKGROUND

Despite medical benefits, hydroxyurea adherence in adolescents is often poor. As part of a baseline assessment of 28 youth (10-18 years) parent dyads who participated in a 6-month feasibility trial to improve hydroxyurea adherence, we measured the relationship between greater barriers to adherence and health-related quality of life (HRQL) from youth and parent perspectives.

PROCEDURE

Barriers were measured using the Adolescent and Parent Medication Barriers Scales with nine hydroxyurea items added. Barriers reported by ≥25% of the sample were considered common. Generic and disease-specific HRQL were measured by PedsQL and PedsQL Sickle Cell Disease modules. Data were analyzed using descriptive statistics, Cronbach alpha, Spearman correlation coefficients, and paired t tests.

RESULTS

Fifty-six subjects (28 dyads) participated. Youth reported greater barriers compared with parents (5.0 ± 3.9 and 3.5 ± 3.2; P = 0.03), with >80% of respondents reporting ≥1 barriers. Twelve barriers were reported by ≥25% of adolescents, whereas six were reported by ≥25% of parents. Of these, only two were common to both dyad members. Approximately one-third of youth had generic and disease-specific HRQL scores that fell at or below cutoff scores, suggesting being at risk for impaired HRQL. Greater barriers were inversely associated with poorer generic (parent r = -0.43, P = 0.03; youth r = -0.44, P < 0.001) and disease-specific HRQL (parent r = -0.53, P = 0.005; youth r = -0.53, P < 0.001).

CONCLUSIONS

Hydroxyurea barriers were frequently reported but differed by dyad members' perspective. Greater barriers were associated with poorer generic and disease-specific HRQL. To reduce barriers to hydroxyurea in youth with sickle cell disease, perspectives of both dyad members should be addressed.

New Therapeutic Options for the Treatment of Sickle Cell Disease

Sickle cell disease (SCD; ORPHA232; OMIM # 603903) is a chronic and invalidating disorder distributed worldwide, with high morbidity and mortality. Given the disease complexity and the multiplicity of pathophysiological targets, development of new therapeutic options is critical, despite the positive effects of hydroxyurea (HU), for many years the only approved drug for SCD. New therapeutic strategies might be divided into (1) pathophysiology-related novel therapies and (2) innovations in curative therapeutic options such as hematopoietic stem cell transplantation and gene therapy. The pathophysiology related novel therapies are: a) Agents which reduce sickling or prevent sickle red cell dehydration; b) Agents targeting SCD vasculopathy and sickle cell-endothelial adhesive events; c) Anti-oxidant agents. This review highlights new therapeutic strategies in SCD and discusses future developments, research implications, and possible innovative clinical trials.

Red blood cell transfusion therapy for sickle cell patients with frequent painful events

BACKGROUND

Recurrent pain events or chronic pain are among the most common complications of sickle cell disease. Despite attempts to maximize adherence to and dosing of hydroxyurea, some patients continue to suffer from pain. Our institution developed a program to initiate chronic red blood cell transfusions for one year in patients clinically deemed to have high healthcare utilization from sickle cell pain, despite being prescribed hydroxyurea.

PROCEDURE

An institutional review board approved retrospective study to evaluate the health outcomes associated with a one-year red blood cell transfusion protocol in sickle cell patients experiencing recurrent pain events as compared with the health outcomes for these patients in the one year prior to receiving transfusion therapy. We performed a matched-pair analysis using a Wilcoxon signed rank to determine the impact of transfusion therapy on clinic visits, emergency department visits, hospital admissions, hospitalization days, and opioid prescriptions filled.

RESULTS

One year of transfusion therapy significantly reduced the number of total emergency department visits for pain (6 vs 2.5 pain visits/year, P = 0.005), mean hospitalizations for pain (3.4 vs 0.9 pain admissions/year), and mean hospital days per year for pain crisis (23.5 vs 4.5, P = 0.0001), as compared with the one year prior to transfusion therapy. We identified no significant difference in opioid prescriptions filled during the year of transfusion therapy.

CONCLUSION

Patients with frequent pain episodes may benefit from one year of transfusion therapy.

Healthcare utilization and hydroxyurea adherence in youth with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) complications lead to poor health-related quality of life (HRQOL) and increased healthcare utilization in this population, which could be mitigated with hydroxyurea therapy; however, adherence is suboptimal. We assessed the relationship of healthcare utilization to hydroxyurea adherence and HRQOL amongst youth with SCD.

METHODS

Thirty-four patients with SCD (median age 14 years, IQR 12-18) on hydroxyurea participated in this cross-sectional study and completed Morisky Adherence Scale 8-items and Patient Reported Outcomes Measurement Information System (PROMIS®) HRQOL measures. A medical chart review was conducted to assess healthcare utilization.

RESULTS

Participants with more frequent hospitalizations and emergency room (ER) visits and longer length of stay (LOS) had significantly lower fetal hemoglobin (r_s=-0.44; r_s=-0.45; r_s=-0.46, p < 0.05) and mean corpuscular volume (r_s=-0.47; r_s=-0.42; r_s=-0.48, p < 0.05), respectively. More frequent hospitalizations and ER visits and longer LOS correlated significantly with worse fatigue (r_s=0.51; r_s=0.41; r_s=0.53, p < 0.05), pain (r_s=0.41; r_s=0.38; r_s=0.47, p < 0.05), physical function mobility (r_s=-0.67; r_s=-0.59; r_s=-0.67, p < 0.05), depression (r_s=0.38; r_s=0.31; r_s=0.42, p < 0.05), and social isolation (r_s=0.76; r_s=0.76; r_s=-0.84, p < 0.05), respectively.

CONCLUSIONS

We conclude that increased healthcare utilization in youth with SCD is associated with low adherence to hydroxyurea and worse HRQOL domain scores. It is important emphasize the clinical benefits of high adherence to hydroxyurea, particularly among youth with SCD. Future longitudinal studies are warranted to assess the directionality of these relationships, and may reveal modifiable behavioral factors associated with early changes in hydroxyurea adherence levels.

HABIT, a Randomized Feasibility Trial to Increase Hydroxyurea Adherence, Suggests Improved Health-Related Quality of Life in Youths with Sickle Cell Disease

OBJECTIVES

To examine the effect of a community health worker (CHW) intervention, augmented by tailored text messages, on adherence to hydroxyurea therapy in youths with sickle cell disease, as well as on generic and disease-specific health-related quality of life (HrQL) and youth-parent self-management responsibility concordance.

STUDY DESIGN

We conducted a 2-site randomized controlled feasibility study (Hydroxyurea Adherence for Personal Best in Sickle Cell Treatment [HABIT]) with 2:1 intervention allocation. Youths and parents participated as dyads. Intervention dyads received CHW visits and text message reminders. Data were analyzed using descriptive statistics, the Wilcoxon signed-rank test, and growth models adjusting for group assignment, time, and multiple comparisons. Changes in outcomes from 0 to 6 months were compared with their respective minimal clinically important differences.

RESULTS

A total of 28 dyads (mean age of youths, 14.3 ± 2.6 years; 50% Hispanic) participated (18 in the intervention group, 10 in the control group), with 10.7% attrition. Accounting for group assignment, time, and multiple comparisons, at 6 months intervention youths reported improved generic HrQL total score (9.8 points; 95% CI, 0.4-19.2) and Emotions subscale score (15.0 points; 95% CI, 1.6-28.4); improved disease-specific subscale scores for Worry I (30.0 points; 95% CI, 8.5-51.5), Emotions (37.0 points, 95% CI, 9.4-64.5), and Communication I (17.8 points; 95% CI, 0.5-35.1); and 3-month dyad self-management responsibility concordance (3.5 points; 95% CI, -0.2 to 7.1). There were no differences in parent proxy-reported HrQL measures at 6 months.

CONCLUSIONS

These findings add to research examining effects of behavioral interventions on HrQL outcomes in youths with sickle cell disease.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02029742.

Fetal Hemoglobin Induction by Epigenetic Drugs

Fetal hemoglobin (HbF) inhibits the root cause of sickle pathophysiology, sickle hemoglobin polymerization. Individuals who naturally express high levels of HbF beyond infancy thus receive some protection from sickle complications. To mimic this natural genetic experiment using drugs, one guiding observation was that HbF is increased during recovery of bone marrow from extreme stress. This led to evaluation and approval of the cytotoxic (cell killing) drug hydroxyurea to treat sickle cell disease. Cytotoxic approaches are limited in potency and sustainability, however, since they require hematopoietic reserves sufficient to repeatedly mount recoveries from stress that destroys their counterparts, and such reserves are finite. HbF induction even by stress ultimately involves chromatin remodeling of the gene for HbF (HBG), therefore, a logical alternative approach is to directly inhibit epigenetic enzymes that repress HBG-implicated enzymes include DNA methyltransferase 1, histone deacetylases, lysine demethylase 1, protein arginine methyltransferase 5, euchromatic histone lysine methyltransferase 2 and chromodomain helicase DNA-binding protein 4. Clinical proof-of-principle that this alternative, noncytotoxic approach can generate substantial HbF and total hemoglobin increases has already been generated. Thus, with continued careful attention to fundamental biological and pharmacologic considerations (reviewed herein), there is potential that rational, molecular-targeted, safe and highly potent disease-modifying therapy can be realized for patients with sickle cell disease, with the accessibility and cost-effective properties needed for world-wide effect.

Randomized feasibility trial to improve hydroxyurea adherence in youth ages 10-18 years through community health workers: The HABIT study

INTRODUCTION

The main therapeutic intervention for sickle cell disease (SCD) is hydroxyurea (HU). The effect of HU is largely through dose-dependent induction of fetal hemoglobin (HbF). Poor HU adherence is common among adolescents.

METHODS

Our 6-month, two-site pilot intervention trial, "HABIT," was led by culturally aligned community health workers (CHWs). CHWs performed support primarily through home visits, augmented by tailored text message reminders. Dyads of youth with SCD ages 10-18 years and a parent were enrolled. A customized HbF biomarker, the percentage decrease from each patients' highest historical HU-induced HbF, "Personal best," was used to qualify for enrollment and assess HU adherence. Two primary outcomes were as follows: (1) intervention feasibility and acceptability and (2) HU adherence measured in three ways: monthly percentage improvement toward HbF Personal best, proportion of days covered (PDC) by HU, and self-report.

RESULTS

Twenty-eight dyads were enrolled, of which 89% were retained. Feasibility and acceptability were excellent. Controlling for group assignment and month of intervention, the intervention group improved percentage decrease from Personal best by 2.3% per month during months 0-4 (P = 0.30), with similar improvement in adherence demonstrated using pharmacy records. Self-reported adherence did not correlate. Dyads viewed CHWs as supportive for learning about SCD and HU, living with SCD and making progress in coordinated self-management responsibility to support a daily HU habit. Most parents and youth appreciated text message HU reminders.

CONCLUSIONS

The HABIT pilot intervention demonstrated feasibility and acceptability with promising effect toward improved medication adherence. Testing in a larger multisite intervention trial is warranted.

Fetal haemoglobin induction in sickle cell disease

Fetal haemoglobin (HbF, α2γ2) induction has long been an area of investigation, as it is known to ameliorate the clinical complications of sickle cell disease (SCD). Progress in identifying novel HbF-inducing strategies has been stymied by limited understanding of gamma (γ)-globin regulation. Genome-wide association studies (GWAS) have identified variants in BCL11A and HBS1L-MYB that are associated with HbF levels. Functional studies have established the roles of BCL11A, MYB, and KLF1 in γ-globin regulation, but this information has not yielded new pharmacological agents. Several drugs are under investigation in clinical trials as HbF-inducing agents, but hydroxycarbamide remains the only widely used pharmacologic therapy for SCD. Autologous transplant of edited haematopoietic stem cells holds promise as a cure for SCD, either through HbF induction or correction of the causative mutation, but several technical and safety hurdles must be overcome before this therapy can be offered widely, and pharmacological therapies are still needed.

Oral tetrahydrouridine and decitabine for non-cytotoxic epigenetic gene regulation in sickle cell disease: A randomized phase 1 study

BACKGROUND

Sickle cell disease (SCD), a congenital hemolytic anemia that exacts terrible global morbidity and mortality, is driven by polymerization of mutated sickle hemoglobin (HbS) in red blood cells (RBCs). Fetal hemoglobin (HbF) interferes with this polymerization, but HbF is epigenetically silenced from infancy onward by DNA methyltransferase 1 (DNMT1).

METHODS AND FINDINGS

To pharmacologically re-induce HbF by DNMT1 inhibition, this first-in-human clinical trial (NCT01685515) combined 2 small molecules-decitabine to deplete DNMT1 and tetrahydrouridine (THU) to inhibit cytidine deaminase (CDA), the enzyme that otherwise rapidly deaminates/inactivates decitabine, severely limiting its half-life, tissue distribution, and oral bioavailability. Oral decitabine doses, administered after oral THU 10 mg/kg, were escalated from a very low starting level (0.01, 0.02, 0.04, 0.08, or 0.16 mg/kg) to identify minimal doses active in depleting DNMT1 without cytotoxicity. Patients were SCD adults at risk of early death despite standard-of-care, randomized 3:2 to THU-decitabine versus placebo in 5 cohorts of 5 patients treated 2X/week for 8 weeks, with 4 weeks of follow-up. The primary endpoint was ≥ grade 3 non-hematologic toxicity. This endpoint was not triggered, and adverse events (AEs) were not significantly different in THU-decitabine-versus placebo-treated patients. At the decitabine 0.16 mg/kg dose, plasma concentrations peaked at approximately 50 nM (Cmax) and remained elevated for several hours. This dose decreased DNMT1 protein in peripheral blood mononuclear cells by >75% and repetitive element CpG methylation by approximately 10%, and increased HbF by 4%-9% (P < 0.001), doubling fetal hemoglobin-enriched red blood cells (F-cells) up to approximately 80% of total RBCs. Total hemoglobin increased by 1.2-1.9 g/dL (P = 0.01) as reticulocytes simultaneously decreased; that is, better quality and efficiency of HbF-enriched erythropoiesis elevated hemoglobin using fewer reticulocytes. Also indicating better RBC quality, biomarkers of hemolysis, thrombophilia, and inflammation (LDH, bilirubin, D-dimer, C-reactive protein [CRP]) improved. As expected with non-cytotoxic DNMT1-depletion, platelets increased and neutrophils concurrently decreased, but not to an extent requiring treatment holds. As an early phase study, limitations include small patient numbers at each dose level and narrow capacity to evaluate clinical benefits.

CONCLUSION

Administration of oral THU-decitabine to patients with SCD was safe in this study and, by targeting DNMT1, upregulated HbF in RBCs. Further studies should investigate clinical benefits and potential harms not identified to date.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01685515.