Therapy For Sickle Cell Disease Research Articles

Novel gene therapies for sickle cell disease, Duchenne muscular dystrophy, and hemophilia A.

This article discusses novel genetic therapies for sickle cell disease, Duchenne muscular dystrophy, and hemophilia A. Gene therapies have the potential to deliver more targeted and effective approaches to treatment, especially for rare diseases for which the availability of approved therapies is limited. This article describes the first FDA-approved CRISPR/Cas9 treatment and the treatment protocols, indications, warnings, precautions, cost, and contraindications of four novel genetic therapies.

Treating Sickle Cell Disease: Gene Therapy Approaches.

Sickle cell disease (SCD) is a hereditary blood disorder characterized by the presence of abnormal hemoglobin molecules and thus distortion (sickling) of the red blood cells. SCD causes chronic pain and organ damage and shortens life expectancy. Gene therapy emerges as a potentially curative approach for people with SCD who lack a matched sibling donor for hematopoietic stem cell transplantation. Here, we review recent progress in gene therapy for SCD and focus on innovative technologies that target the genetic roots of the disease. We also review the challenges associated with gene therapy, including oncogenic risks, and the need for refined delivery methods. Despite these hurdles, the rapidly evolving landscape of gene therapy for SCD raises hope for a paradigm shift in the treatment of this debilitating disease. As research progresses, a deeper understanding of the molecular mechanisms involved and continuous improvements in gene-editing technologies promise to bring gene therapy for SCD closer to mainstream clinical application, offering a transformative, curative option for patients with this genetic disorder.

CureSCi Metadata Catalog-finding and harmonizing studies for secondary analysis of hydroxyurea use for sickle cell disease.

Sickle cell disease (SCD) is a rare group of inherited red blood cell disorders that affect hemoglobin, resulting in serious multi-system complications. The limited number of patients available to participate in research studies can inhibit investigating sophisticated relationships. Secondary analysis is a research method that involves using existing data to answer new research questions. Data harmonization enables secondary analysis by combining data across studies, especially helpful for rare disease research where individual studies may be small. The National Heart, Lung, and Blood Institute Cure Sickle Cell Initiative (CureSCi) Metadata Catalog is a web-based tool to identify SCD study datasets for conducting data harmonization and secondary analysis. We present a proof-of-concept secondary analysis to explore factors associated with discontinuation of hydroxyurea, a safe and effective first line SCD therapy, to illustrate the utility of the CureSCi Metadata Catalog to expedite and enable more robust SCD research. We performed secondary analysis of SCD studies using a multi-step workflow: develop research questions, identify study datasets, identify variables of interest, harmonize variables, and establish an analysis method. A harmonized dataset consisting of eight predictor variables across five studies was created. Secondary analysis involved a generalized linear model was employed to identify factors that significantly impact hydroxyurea discontinuation. The CureSCi Metadata Catalog provided a platform to efficiently find relevant studies and design a harmonization strategy to prepare data for secondary analysis. Multivariate analysis of the harmonized identified that patients who are older, are female, had a history of blood transfusion therapy, had episodes of acute chest syndrome, and had the SC sickle cell genotype are more likely to stop hydroxyurea treatment. This secondary analysis provides a template for how the CureSCi Metadata Catalog expedites dataset discovery of sickle cell studies for identifying relationships between variables or validating existing findings.

Gene Therapies for Sickle Cell Disease.

Background: Sickle cell disease (SCD) is a prevalent autosomal recessive hemoglobinopathy affecting millions worldwide, particularly individuals of African ancestry. Sickle cell disease is a lifelong condition associated with a negative impact on quality of life and mortality, causing complications such as painful vaso-occlusive episodes, acute chest syndrome, stroke, long-term anemia, and end-organ damage. Currently, there are 4 U.S. Food and Drug Administration (FDA)-approved drugs, including hydroxyurea, l-glutamine, voxelotor, and crizanlizumab, which work to alleviate symptoms and prevent complications associated with SCD, albeit without addressing the underlying cause of SCD. Allogeneic hematopoietic stem cell transplant (HSCT) has shown promise as a curative approach to SCD but is limited by donor availability and associated complications. This paper aims to review the efficacy and safety of exagamglogene autotemcel and lovotibeglogene autotemcel for managing patients with SCD, including their place in therapy, cost, and accessibility in clinical care. Data Sources: The authors searched PubMed and Medline from 2017 to 2024, for primary literature on both exagamglogene autotemcel and lovotibeglogene autotemcel. Results: The authors identified relevant studies and summarized the data on the two gene therapies. Conclusion: Exagamglogene autotemcel and lovotibeglogene autotemcel are two management strategies that address the underlying cause of SCD and provide curative potential for patients with SCD.

Budget Impact of Disease-Modifying Treatments and a CRISPR Gene-Edited Therapy for Sickle Cell Disease.

Treatment of sickle cell disease (SCD) has traditionally focused on symptomatic and preventative care. Recent advances in novel therapeutic developments, likely to be orphan-designated, are anticipated to carry a substantial price tag. This study assesses the potential budget impact of adopting disease-modifying treatments, crizanlizumab and voxelotor, and pioneering CRISPRgene-edited therapy, CTX001, in the Belgian healthcare system. The perspective of the Belgian healthcare payer (RIZIV-INAMI including patient copayments), a 5-year horizon with a 2-10% uptake of disease-modifying interventions, and a 2% uptake of CTX001 were considered. Data, encompassing target population, current (chronic and acute management, curative hematopoietic stem cell transplantation) and new (crizanlizumab, voxelotor, and CTX001) interventions, clinical effectiveness, adverse events, healthcare resource utilization, and associated costs, were gathered through a comprehensive literature review (first phase) and two Delphi panels involving hematologists (second phase). The cost difference between a "world with and without crizanlizumab, voxelotor, and CTX001" was calculated to obtain the budget impact.Three scenario analyses were conducted: a 5-13% and 4% uptake analysis, a 10-18% and 8% uptake analysis, respectively for disease-modifying treatments (crizanlizumab and voxelotor) and CTX001, and a 0% crizanlizumab uptake and managed entry agreements analysis .A ± 20% univariate sensitivity analysis was performed to test the robustness of the analysis. The total five-year cumulative budget impact was estimated at €30,024,968, with 91% attributed to drug acquisition costs. The largest budget impact share was for CTX001 (€25,575,150), while crizanlizumab (€2,301,095) and voxelotor (€2,148,723) was relatively small. In scenarios one and three, a two-fold increase of the cumulative budget impact to €60,731,772 and a four-fold increase to €120,846,256 from the base case was observed. In scenario three, this budget impact decreased by 63% to €11,212,766. Patient population size, number of treated patients, and drug costs influenced the analysis the most, while discontinuation, acute crisis, and adverse event rates had comparatively minimal impact. Belgian decision-makers may consider alternative financing models, such as outcome-based risk-sharing agreements or annuities, to ensure sustainable coverage of these treatments. This study adheres to recommended practices for assessing budget impact of orphan drugs, distinguishing it from earlier studies with potentially weaker methodologies.

The Double-Edged Sword of Extremely High Prices for Gene Therapies in Sickle Cell Disease

This Viewpoint discusses the high cost of new gene therapies for sickle cell disease, the challenges these costs pose for health care access, and new policy approaches to ensure fair reimbursement for payers and manufacturers without further increasing health care costs or barriers to access for underserved populations.

A budget impact analysis of gene therapy for sickle cell disease: an updated analysis

A budget impact analysis of gene therapy for sickle cell disease: an updated analysis

A roadmap for affordable genetic medicines.

Twenty genetic therapies have been approved by the US Food and Drug Administration to date, a number that now includes the first CRISPR genome-editing therapy for sickle cell disease-CASGEVY (exagamglogene autotemcel, Vertex Pharmaceuticals). This extraordinary milestone is widely celebrated owing to the promise for future genome-editing treatments of previously intractable genetic disorders and cancers. At the same time, such genetic therapies are the most expensive drugs on the market, with list prices exceeding US$4 million per patient. Although all approved cell and gene therapies trace their origins to academic or government research institutions, reliance on for-profit pharmaceutical companies for subsequent development and commercialization results in prices that prioritize recouping investments, paying for candidate product failures and meeting investor and shareholder expectations. To increase affordability and access, sustainable discovery-to-market alternatives are needed that address system-wide deficiencies. Here we present recommendations of a multidisciplinary task force assembled to chart such a path. We describe a pricing structure that, once implemented, could reduce per-patient cost tenfold and propose a business model that distributes responsibilities while leveraging diverse funding sources. We also outline how academic licensing provisions, manufacturing innovation and supportive regulations can reduce cost and enable broader patient treatment.

Chronic automated red cell exchange therapy for sickle cell disease.

The data to support chronic automated red cell exchange (RCE) in sickle cell disease (SCD) outside of stroke prevention, is limited, especially in adults. A retrospective analysis was conducted of patients with SCD who were referred for chronic RCE at our institution over a 10-year period. Data that were evaluated included patient demographics, referral indications, and procedural details (e.g., vascular access, adverse events, etc.). In a subanalysis, the number of annual acute care encounters during 3 years of chronic RCE was compared with that in the year preceding the first RCE. A total of 164 patients were referred for chronic RCE: median age was 28 years (interquartile range [IQR] = 22-36) at referral and 60% were female. Seventy (42.6%) were naïve to chronic transfusion (simple or RCE) prior to referral. The leading indications for referral were refractory pain (73/164, 44.5%) and iron overload (57/164, 34.7%). A total of 5090 procedures occurred during the study period (median = 19, IQR = 5-45). Of the 138 patients who had central vascular access, 8 (6%) and 16 (12%) had ≥1 central-line-related thrombosis and/or infection, respectively. Of those who were not RBC alloimmunized at initiation of RCE, 12/105 (11.4%) developed new antibodies during chronic RCE. In those 30 patients who were adherent to therapy for 3 years, there was no significant difference in acute care encounters following initiation of RCE. Prospective clinical trials are needed to determine which patients are most likely to benefit from chronic RCE and refine selection accordingly.

Dismantling cost and infrastructure barriers to equitable access to gene therapies for sickle cell disease.

Dismantling cost and infrastructure barriers to equitable access to gene therapies for sickle cell disease.

Study protocol for ADHERE (Applying Directly observed therapy to HydroxyurEa to Realize Effectiveness): Using small business partnerships to deliver a scalable and novel hydroxyurea adherence solution to youth with sickle cell disease.

Sickle cell disease (SCD) is an inherited blood disorder that affects approximately 100,000 Americans, primarily from underrepresented racial minority populations, and results in costly, multi-organ complications. Hydroxyurea, the primary disease-modifying therapy for SCD, is effective at reducing most complications; however, adherence to hydroxyurea remains suboptimal and is the primary barrier to clinical effectiveness. Video directly observed therapy (VDOT) has shown promise as an adherence-promoting intervention for hydroxyurea, yet previous VDOT trials were limited by high attrition from gaps in technology access, use of unvalidated adherence measures, and healthcare system limitations of delivering VDOT to patients. As such, we fostered a small business partnership to compare VDOT for hydroxyurea to attention control to address previous shortcomings, promote equitable trial participation, and maximize scalability. VDOT will be administered by Scene Health (formerly emocha Health) and adherence monitoring will be performed using a novel electronic adherence monitor developed to meet the unique needs of the target population. Adolescent and young adult patients as well as caregivers of younger patients (<11 years of age) will be recruited. In addition to visit incentives, all participants will be offered a smartphone with a data plan to ensure all participants have equal opportunity to complete study activities. The primary objectives of this pilot, multi-center, randomized controlled trial (RCT) are to assess retention and sustained engagement and to explore needs and preferences for longer-term adherence monitoring and interventions. This RCT is registered with the National Institutes of Health (NCT06264700). Findings will inform a future efficacy RCT applying VDOT to hydroxyurea to address adherence gaps and improve outcomes within this vulnerable population.

Non-viral DNA delivery and TALEN editing correct the sickle cell mutation in hematopoietic stem cells

Sickle cell disease is a devastating blood disorder that originates from a single point mutation in the HBB gene coding for hemoglobin. Here, we develop a GMP-compatible TALEN-mediated gene editing process enabling efficient HBB correction via a DNA repair template while minimizing risks associated with HBB inactivation. Comparing viral versus non-viral DNA repair template delivery in hematopoietic stem and progenitor cells in vitro, both strategies achieve comparable HBB correction and result in over 50% expression of normal adult hemoglobin in red blood cells without inducing β-thalassemic phenotype. In an immunodeficient female mouse model, transplanted cells edited with the non-viral strategy exhibit higher engraftment and gene correction levels compared to those edited with the viral strategy. Transcriptomic analysis reveals that non-viral DNA repair template delivery mitigates P53-mediated toxicity and preserves high levels of long-term hematopoietic stem cells. This work paves the way for TALEN-based autologous gene therapy for sickle cell disease.

A simplified G-CSF–free procedure allows for in vivo HSC gene therapy of sickle cell disease in a mouse model

AbstractWe have reported the direct repair of the sickle cell mutation in vivo in a disease model using vectorized prime editors after hematopoietic stem cell (HSC) mobilization with granulocyte colony-stimulating factor (G-CSF)/AMD3100. The use of G-CSF for HSC mobilization is a hurdle for the clinical translation of this approach. Here, we tested a G-CSF-free mobilization regimen using WU-106, an inhibitor of integrin α4β1, plus AMD3100 for in vivo HSC prime editing in sickle cell disease (SCD) mice. Mobilization with WU-106 + AMD3100 in SCD mice was rapid and efficient. In contrast to the G-CSF/AMD3100 approach, mobilization of activated granulocytes and elevation of the key proinflammatory cytokine interleukin-6 in the serum were minimal. The combination of WU-106 + AMD3100 mobilization and IV injection of the prime editing vector together with in vivo selection resulted in ∼23% correction of the SCD mutation in the bone marrow and peripheral blood cells of SCD mice. The treated mice demonstrated phenotypic correction, as reflected by normalized blood parameters and spleen size. Editing frequencies were significantly increased (29%) in secondary recipients, indicating the preferential mobilization/transduction of long-term repopulating HSCs. Using this approach, we found <1% undesired insertions/deletions and no detectable off-target editing at the top-scored potential sites. Our study shows that in vivo transduction to treat SCD can now be done within 2 hours involving only simple IV injections with a good safety profile. The same-day mobilization regimen makes in vivo HSC gene therapy more attractive for resource-poor settings, where SCD does the most damage.

Precision in Action: The Role of Clustered Regularly Interspaced Short Palindromic Repeats/Cas in Gene Therapies.

Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-associated enzyme-CAS holds great promise for treating many uncured human diseases and illnesses by precisely correcting harmful point mutations and disrupting disease-causing genes. The recent Food and Drug Association (FDA) approval of the first CRISPR-based gene therapy for sickle cell anemia marks the beginning of a new era in gene editing. However, delivering CRISPR specifically into diseased cells in vivo is a significant challenge and an area of intense research. The identification of new CRISPR/Cas variants, particularly ultra-compact CAS systems with robust gene editing activities, paves the way for the low-capacity delivery vectors to be used in gene therapies. CRISPR/Cas technology has evolved beyond editing DNA to cover a wide spectrum of functionalities, including RNA targeting, disease diagnosis, transcriptional/epigenetic regulation, chromatin imaging, high-throughput screening, and new disease modeling. CRISPR/Cas can be used to engineer B-cells to produce potent antibodies for more effective vaccines and enhance CAR T-cells for the more precise and efficient targeting of tumor cells. However, CRISPR/Cas technology has challenges, including off-target effects, toxicity, immune responses, and inadequate tissue-specific delivery. Overcoming these challenges necessitates the development of a more effective and specific CRISPR/Cas delivery system. This entails strategically utilizing specific gRNAs in conjunction with robust CRISPR/Cas variants to mitigate off-target effects. This review seeks to delve into the intricacies of the CRISPR/Cas mechanism, explore progress in gene therapies, evaluate gene delivery systems, highlight limitations, outline necessary precautions, and scrutinize the ethical considerations associated with its application.

Reviewing the impact of hydroxyurea on DNA methylation and its potential clinical implications in sickle cell disease.

Hydroxyurea (HU) is the most common drug therapy for sickle cell disease (SCD). The clinical benefits of HU derive from its upregulation of fetal hemoglobin (HbF), which reduces aggregation of the mutated sickle hemoglobin protein (HbS) and reduces SCD symptoms and complications. However, some individuals do not respond to HU, or stop responding over time. Unfortunately, current understanding of the mechanism of action of HU is limited, hindering the ability of clinicians to identify those patients who will respond to HU and to optimize treatment for those receiving HU. Given that epigenetic modifications are essential to erythropoiesis and HbF expression, we hypothesize that some effects of HU may be mediated by epigenetic modifications, specifically DNA methylation. However, few studies have investigated this possibility and the effects of HU on DNA methylation remain relatively understudied. In this review, we discuss the evidence linking HU treatment to DNA methylation changes and associated gene expression changes, with an emphasis on studies that were performed in individuals with SCD. Overall, although HU can affect DNA methylation, research on these changes and their clinical effects remains limited. Further study is likely to contribute to our understanding of hematopoiesis and benefit patients suffering from SCD.

TP53 mutation screening for patients at risk of myeloid malignancy.

6546 Background: Cellular therapy is a promising approach for many diseases but is associated with a risk of subsequent myelodysplastic syndrome and/or acute myeloid leukemia, also known as therapy-related myeloid neoplasms (tMN). This phenomenon has recently been described with allogeneic hematopoietic cell transplantation (HCT) and gene therapy for sickle cell disease (SCD). Mutation(s) in functional domains of TP53 are often associated with the development of tMN but currently no prospective screening or monitoring technology is available. Methods: A next-generation sequencing (NGS) assay with unique molecular identifiers (UMI) and bioinformatic noise-suppression was designed to discover somatic mutations at a variant allele frequency (VAF) 1% throughout the TP53gene. The background error profile at each base position was calculated using blood genomic DNA from healthy donors. The minimal detectable allele fraction with 95% confidence (MDAF) was calculated for all reported known AML/tMN TP53 hotspots. Orthogonal validation was performed using droplet digital PCR (ddPCR). Results: The median error corrected sequencing depth at 62 known TP53 hotspot regions was 14,512 (95% CI: 14,769 – 15,430) with a theoretical median de novo NGS variant discovery limit of 0.058% (range: 0.037% - 0.13%). Experimental evidence of assay performance characteristics was produced using serial dilutions of 4 missense, 2 splicing, and 1 frameshift TP53 variants with 100% discovery specificity observed (lowest detected VAF range: 0.05 – 0.12%). High correlation was observed in quantification using NGS discovery and ddPCR validation ( r = 0.958, p&lt;0.0001). Pre- and post-HCT clinical samples from 19 patients with SCD, 11 of which had graft failure including 4 who developed tMN, were screened for TP53 mutations. In all tMN cases, the AML-associated TP53 variant was detectable at least 6 months and up to 2.5 years prior to clinical diagnosis of myeloid malignancy. In contrast, no pathogenic TP53 variants were detected in 15 SCD patients who underwent HCT but did not develop tMN. Conclusions: This study provides generalizable evidence that ultra-sensitive discovery of TP53 mutations prior to cellular therapy is possible and could be a potentially valuable clinical tool to screen for tMN risk.

Empowering Minds, Easing Pain: The Role of Talk Therapy in Sickle Cell Disease

Empowering Minds, Easing Pain: The Role of Talk Therapy in Sickle Cell Disease

Current and Future Therapeutics for Treating Patients with Sickle Cell Disease.

Sickle cell disease (SCD) is the most common genetic blood disorder in the United States, with over 100,000 people suffering from this debilitating disease. SCD is caused by abnormal hemoglobin (Hb) variants that interfere with normal red blood cell (RBC) function. Research on SCD has led to the development and approval of several new SCD therapies in recent years. The recent FDA-approved novel gene therapies are potentially curative, giving patients an additional option besides a hematopoietic bone marrow transplant. Despite the promise of existing therapies, questions remain regarding their long-term pharmacological effects on adults and children. These questions, along with the exorbitant cost of the new gene therapies, justify additional research into more effective therapeutic options. Continual research in this field focuses on not only developing cheaper, more effective cures/treatments but also investigating the physiological effects of the current therapies on SCD patients, particularly on the brain and kidneys. In this article, we undertake a comprehensive review of ongoing clinical trials with completion dates in 2024 or later. Our exploration provides insights into the landscape of current therapeutics and emerging novel therapies designed to combat and potentially eradicate SCD, including the latest FDA-approved gene therapies.

Revolutionary breakthrough: FDA approves CASGEVY, the first CRISPR/Cas9 gene therapy for sickle cell disease.

Sickle cell disease (SCD) is a hereditary hemoglobinopathy resulting from a β-globin chain mutation that causes abnormal hemoglobin (HbS) polymerization and leads to severe complications. Current treatment options primarily focus on symptom management, with limited curative potential. Recently, Casgevy, the first CRISPR/Cas9-based gene therapy for SCD, has received breakthrough FDA approval. Clinical trials have shown that Casgevy administered to patients aged older than or equal to 12 years enables precise modifications in hematopoietic stem cells, resulting in elevated fetal hemoglobin (HbF) levels and a significant reduction in vaso-occlusive events. Unlike conventional treatments, this therapy offers a curative approach and eliminates the need for recurrent transfusions and transplants, thereby improving the quality of life of patients with SCD. Casgevy has emerged as a beacon of hope for SCD patients and signifies a potential paradigm shift in SCD management due to its safety, curative potential, and transformative impact, positioning it as a groundbreaking intervention. Nevertheless, ethical considerations surrounding CRISPR technology and regulatory frameworks must be addressed to ensure responsible application and equitable access to this one-time gene editing therapy. As the authors celebrate this scientific advancement, sustained interdisciplinary collaboration and ethical scrutiny are essential to navigating the evolving landscape of CRISPR technology in medicine. This review aims to provide a detailed insight into the application of Casgevy, challenges associated with its application, future prospects of this therapy, and its comparison with existing treatment options for SCD.

Clinical Practice Patterns in Sickle Cell Disease Treatment: Disease-modifying and Potentially Curative Therapies.

Therapeutic options for sickle cell disease (SCD) have increased recently as well as the development of updated national guidelines. It is not known how these options are being offered or to what degree guidelines are incorporated into clinical practice. This study aimed to describe practice patterns for pediatric hematologists regarding the use of disease-modifying and potentially curative therapies for SCD. A 9-section, cross-sectional electronic survey was disseminated during a 3-month period via SurveyMonkey, to members of the American Society of Pediatric Hematology/Oncology Hemoglobinopathy Special Interest Group (ASPHO HSIG). A total of 88 physician members of the ASPHO HSIG were surveyed. Ninety percent of respondents (72/80) start hydroxyurea routinely in patients with HbSS and HbSβ 0 thalassemia, regardless of disease severity. Laboratory monitoring was recommended every 3 months for stable dosing in 63.8% (51/80). New therapies were recommended for patients on hydroxyurea who were still experiencing SCD complications: L-glutamine 68.5% (37/54) or crizanlizumab 93.1% (54/58). Voxelotor was recommended for patients on hydroxyurea with low hemoglobin in 65.1% (43/66) of cases. Matched sibling transplant was considered for any disease severity by 55.1% (38/69). Gene therapy trials are offered on-site by 29% (20/69). Our study demonstrated the enhanced utilization of hydroxyurea while revealing the unexplored potential of other disease-modifying therapies in SCD. These findings underscore the importance of continued knowledge acquisition about the long-term efficacy of new medical therapies and addressing barriers to the use of proven therapies and guide the development of future studies of optimal SCD management.