Advances and innovations in haemophilia treatment

Design organization and clinical processes around patient characteristics: Evidence from a multiple case study of Hemophilia

Background: There is growing evidence of the relevance of designing organization of care around patient characteristics; this is especially true in the case of complex chronic diseases.Purpose: The goal of the paper - that focuses on the analysis of the clinical condition hemophilia in three different centers - is to address two different research questions:1. How can we define, within the same clinical condition, different patient profiles homogeneous in terms of intensity of service required (e.g. number of visits or diagnostics)? 2. What are the conditions to re-organize care around these patient profiles in a multidisciplinary and coordinated manner?Research design: The authors have used a multiple case study approach combining both qualitative and quantitative methodologies; in particularly the semi-structured interviews and the direct observation were aimed to map the process in order to come up with an estimate of the cost of the full cycle of care.Study sample: The research methodology has been applied consistently in three different centers. The selection of the structures has been based on two main different criteria: (i) high standards regarding both organizational and clinical aspects and (ii) willingness from management, nurses and physicians to provide data.Results: The study clearly shows that different patient profiles - within the same clinical condition - trigger a different set of diagnostic and therapeutic activities. It is, thus, important considering patient characteristics in the development and implementation of clinical pathways and this will imply relevant differences in terms of organizational and economic impact.Conclusions: These process-based analyses are very much critical especially if we want to move to a bundled and integrated payment system but, as shown by this study itself, require a lot of time and efforts since our healthcare information systems are still fragmented and vertically designed.

Advances in biopharmaceutical products for hemophilia

Hemophilia is caused by the deficiency of clotting factors due to a single genetic abnormality. Replacement therapies have evolved from plasma-derived to recombinant coagulation factor concentrates but continue to have certain limitations. Monoclonal antibodies are clinical prophylactic treatment options unaffected by inhibitors and have better compliance than coagulation factor concentrates for patients with hemophilia. Gene therapy is a breakthrough in hemophilia treatment, as it drives the hepatic expression of factor VIII or factor IX and requires only a single administration to enable long-term replacement treatment in adult patients. Furthermore, biopharmaceutical products that target new pathways unaffected by inhibitors, including tissue factor pathway inhibitors, activated protein C, and antithrombin, as well as pharmaceutical technology advances to reduce dosing frequency, have demonstrated promising clinical results. This review provides a comprehensive overview of these biopharmaceutical products and explores the future of hemophilia treatment.

What is a cure through gene therapy? An analysis and evaluation of the use of "cure"

The development of gene therapy has always come with the expectation that it will offer a cure for various disorders, of which hemophilia is a paradigm example. However, although the term is used regularly, it is unclear what exactly is meant with "cure". Therefore, the aim of this paper is to analyse how the concept of cure is used in practice and evaluate which of the interpretations is most suitable in discussions surrounding gene therapy. We analysed how cure is used in four different medical fields where the concept raises discussion. We show that cure can be used in three different ways: cure as normalization of the body, cure as obtaining a normal life, or cure as a change in identity. We argue that since cure is a practical term, its interpretation should be context-specific and the various uses can exist simultaneously, as long as their use is suitable to the function the notion of cure plays in each of the settings. We end by highlighting three different settings in the domain of hemophilia gene therapy in which the term cure is used and explore the function(s) it serves in each setting. We conclude that in the clinical application of gene therapy, it could be better to abandon the term cure, whereas more modest and specified definitions of cure are required in the context of health resource allocation decisions and decisions on research funding.

Hemostats in the clinic

Given the prevalence of hematological conditions, surgeries, and trauma incidents, hemostats-therapeutics designed to control and arrest bleeding-are an important tool in patient care. The prophylactic and therapeutic use of hemostats markedly enhances survival rates and improves the overall quality of life of patients suffering from these conditions. Since their inception in the 1960s, hemostats have witnessed remarkable progress in terms of the active ingredients utilized, therapeutic outcomes, demonstrated efficacy, and the storage stability. In this review, we provide a comprehensive analysis of commercially available hemostats approved by the FDA, along with newer investigative hemostats currently in active clinical trials. We delve into the modality of active ingredients, route of administration, formulation type, and disease indications of these approved and investigative hemostats. Further, we analyze the trends observed in the hemostat actives for Hemophilia A and B, concluding with insights into the emerging patterns and noteworthy developments to watch for in this dynamic field.

Chitosan/β-glycerophosphate porous microsphere prepared by facile water-in-water emulsion as a topical hemostatic material

Acute hemorrhage is a major cause of death in many emergency cases. Although many hemostatic materials have been studied in recent years, it is still necessary to develop new hemostatic materials with remarkable efficiency, biosafety, convenient preparation, low cost, and good biodegradability. In this work, novel chitosan (CS)/β-glycerophosphate (β-GP) composite porous microsphere with a uniform size of 210.00 ± 2.14 μm was fabricated through water-in-water (W/W) emulsion via microencapsulation, which can avoid the use of toxic crosslink chemicals and organic solvents to achieve facile and efficient preparation of microspheres. β-GP could promote the formation of microspheres by enhancing the hydrogen-bonding interaction between CS chains, which contributed to the macro-porous structure. Owing to their large pore size (6.0 μm) and high specific surface area (37.8 m2/g), the CS/β-GP microspheres could absorb water quickly and adsorb protein, red blood cells, and platelets through electrostatic forces to promote blood coagulation. Furthermore, the CS/β-GP microspheres achieved a significantly shortened hemostatic time (45 s) and reduced blood loss (0.03 g) in a rat liver injury model. Rat tail amputation test also showed a satisfactory hemostatic effect. Overall, the green and porous CS/β-GP microspheres can be used as a facile and topical rapid hemostatic material.

Development of mRNA Lipid Nanoparticles: Targeting and Therapeutic Aspects

Lipid nanoparticles (LNPs) have emerged as leading non-viral carriers for messenger RNA (mRNA) delivery in clinical applications. Overcoming challenges in safe and effective mRNA delivery to target tissues and cells, along with controlling release from the delivery vehicle, remains pivotal in mRNA-based therapies. This review elucidates the structure of LNPs, the mechanism for mRNA delivery, and the targeted delivery of LNPs to various cells and tissues, including leukocytes, T-cells, dendritic cells, Kupffer cells, hepatic endothelial cells, and hepatic and extrahepatic tissues. Here, we discuss the applications of mRNA-LNP vaccines for the prevention of infectious diseases and for the treatment of cancer and various genetic diseases. Although challenges remain in terms of delivery efficiency, specific tissue targeting, toxicity, and storage stability, mRNA-LNP technology holds extensive potential for the treatment of diseases.

Impacts of the COVID-19 pandemic on pediatric and adult patients with hemophilia

BACKGROUND

The coronavirus disease 2019 (COVID-19)-associated mortality rate of hemophilia patients is similar to that of the general population, but the risk of hospitalization and bleeding is higher. However, the specific impact of this infection on hemophilia patients remains unknown. We aimed to investigate the impact of the pandemic on the infection susceptibility, symptoms, drug use, and social intercourse of patients with hemophilia.

METHODS

A survey was distributed to 265 patients with hemophilia (185 adults and 80 children) in the Fujian hemophilia therapeutic center (Fuzhou City, China) during the COVID-19 pandemic, and data were collected between January 2022 and January 2023. The impacts of SARS-CoV-2 infection on hemophilia symptoms, drug use, and social intercourse of these patients were investigated, and the association between the recovery time and disease conditions was explored in infected patients.

RESULTS

During the pandemic, compared with adult patients, pediatric patients had significantly reduced social intercourse and outdoor activities because of the fear of contracting COVID-19 (85.0% vs. 66.5%). Bleeding events were also significantly fewer in children than in adults (61.2% vs. 81.1%). The SARS-CoV-2 infection rate was significantly higher in patients living in urban areas than in those living in rural areas (74.3% vs. 53.6%). The duration of symptomatic recovery from COVID-19 was not significantly associated with hemorrhage, type and classification of hemophilia, presence of inhibitors, complications, and vaccination status.

CONCLUSION

Having COVID-19 infection did not significantly influence the symptoms and treatments in patients with hemophilia. Pediatric patients had significantly fewer bleeding events than adults.

Damoctocog Alfa Pegol, a PEGylated B-domain Deleted Recombinant Extended Half-life Factor VIII for the Treatment of Hemophilia A: A Product Review

Damoctocog alfa pegol (BAY 94-9027, Jivi®), is a site-specifically PEGylated, extended half-life recombinant factor VIII (FVIII) that is approved in several European and non-European countries for on-demand treatment and prophylaxis of bleeding in previously treated patients aged ≥ 12 years with hemophilia A. Reliable measurements can be obtained using most one-stage and chromogenic FVIII assays over a wide concentration range. The efficacy, safety and pharmacokinetics (PK) of damoctocog alfa pegol have been studied extensively in the PROTECT VIII clinical trials, and its long-term safety and effectiveness profile is continuing to build through observational and interventional real-world studies. The PK of damoctocog alfa pegol was shown to be improved as compared with that of sucrose-formulated rFVIII (rFVIII-FS, Kogenate®), and was also demonstrated to be non-inferior to and, for some variables, more favorable than rFVIII-Fc fusion protein, efmoroctocog alfa (Elocta®; NCT03364998), rurioctocog alfa pegol (BAX 855, Adynovate®/Adynovi®; NCT04015492), and antihemophilic factor (recombinant) plasma/albumin-free method (rAHF-PFM, Advate®; NCT02483208). Damoctocog alfa pegol was generally well tolerated and none of the patients in any of the clinical trials, including the PROTECT VIII clinical program, HEM-POWR, or ongoing single-center studies, developed FVIII inhibitors. Efficacy for perioperative hemostasis has been demonstrated. Low bleeding rates were achieved across the studies, with twice weekly, every 5-day and every 7-day prophylaxis offering patients ≥ 12 years and their clinicians the chance to tailor treatment to individual needs and lifestyles, while maintaining long-term protection from bleeds and their consequences.

Application of machine learning approaches for predicting hemophilia A severity

BACKGROUND

Hemophilia A (HA) is an X-linked congenital bleeding disorder, which leads to deficiency of clotting factor (F) VIII. It mostly affects males, and females are considered carriers. However, it is now recognized that variants of F8 in females can result in HA. Nonetheless, most females go undiagnosed and untreated for HA, and their bleeding complications are attributed to other causes. Predicting the severity of HA for female patients can provide valuable insights for treating the conditions associated with the disease, such as heavy bleeding.

OBJECTIVES

To predict the severity of HA based on F8 genotype using a machine learning (ML) approach.

METHODS

Using multiple datasets of variants in the F8 and disease severity from various repositories, we derived the sequence for the FVIII protein. Using the derived sequences, we used ML models to predict the severity of HA in female patients.

RESULTS

Utilizing different classification models, we highlight the validity of the datasets and our approach with predictive F1 scores of 0.88, 0.99, 0.93, 0.99, and 0.90 for all the validation sets.

CONCLUSION

Although with some limitations, ML-based approaches demonstrated the successful prediction of disease severity in female HA patients based on variants in the F8. This study confirms previous research findings that ML can help predict the severity of hemophilia. These results can be valuable for future studies in achieving better treatment and clinical outcomes for female patients with HA, which is an urgent unmet need.

Long-Term Efficacy and Safety of Damoctocog Alfa Pegol Prophylaxis in Patients with Haemophilia A Aged 12-<18 Years at Enrolment into PROTECT VIII

INTRODUCTION

The phase 2/3 PROTECT VIII study demonstrated long-term efficacy and safety of damoctocog alfa pegol (BAY 94-9027; Jivi®), a B-domain-deleted recombinant factor VIII (FVIII), site-specifically PEGylated to improve its pharmacokinetic profile. We report a post hoc assessment of bleeding and safety outcomes in the subgroup of patients, aged 12-<18 years at enrolment.

METHOD

PROTECT VIII was a multicentre, open-label study of previously treated males aged 12-65 years with severe haemophilia A (FVIII <1%). Twelve patients were included in this analysis. All received damoctocog alfa pegol prophylaxis for the total time in study (median [range] time in study 4.0 [1.3-6.2] years).

RESULTS

Overall median (Q1; Q3) total and joint annualised bleeding rates were 1.8 (0.4; 5.1) and 0.7 (0.2; 1.8), respectively, for the entire study. During the last 6 months of treatment, eight (66.7%) and ten (83.3%) out of 12 patients experienced zero total and joint bleeds, respectively. No patient developed FVIII inhibitors. No deaths or thrombotic events were reported.

CONCLUSION

Efficacy and safety of damoctocog alfa pegol were confirmed in adolescent patients with haemophilia A, with data for up to 6 years supporting its use as a long-term treatment option in this group as they transition into adulthood.

Thrombin and Thrombin-Incorporated Biomaterials for Disease Treatments

Thrombin, a coagulation-inducing protease, has long been used in the hemostatic field. During the past decades, many other therapeutic uses of thrombin have been developed. For instance, burn treatment, pseudoaneurysm therapy, wound management, and tumor vascular infarction (or tumor vasculature blockade therapy) can all utilize the unique and powerful function of thrombin. Based on their therapeutic effects, many thrombin-associated products have been certificated by the Food and Drug Administration, including bovine thrombin, human thrombin, recombinant thrombin, fibrin glue, etc. Besides, several thrombin-based drugs are currently undergoing clinical trials. In this article, the therapeutic uses of thrombin (from the initial hemostasis to the latest cancer therapy), the commercially available drugs associated with thrombin, and the pros and cons of thrombin-based therapeutics (e.g., adverse immune responses related to bovine thrombin, thromboinflammation, and vasculogenic "rebounds") are summarized. Further, the current challenges and possible future research directions of thrombin-incorporated biomaterials and therapies are discussed. It is hoped that this review may provide a valuable reference for researchers in this field and help them to design safer and more effective thrombin-based drugs for fighting against various intractable diseases.

Cartilage Destruction by Hemophilic Arthropathy Can Be Prevented by Inhibition of the Ferroptosis Pathway in Human Chondrocytes

(1) Background: Around 50% of hemophilia patients develop severe arthropathy, with even subclinical hemorrhage in childhood potentially leading to intra-articular iron deposition, synovia proliferation, neoangiogenesis, and eventual damage to articular cartilage and subchondral bone. Treatments typically include coagulation factor substitution, radiosynoviorthesis, and joint replacement for advanced cases. This study aims to elucidate programmed cell death mechanisms in hemophilic arthropathy (HA) to identify novel treatments. (2) Methods: Human chondrocytes were exposed to lysed/non-lysed erythrocytes, ferroptosis inducer ML-162, cytokines (IL-1ß, TNFα), and ferric citrate, then assessed for metabolic activity, DNA content, and cell death using Alamar Blue, cyQUANT, and Sytox assays. Three-dimensional spheroids served as a cartilage model to study the effects of erythrocytes and ML-162. (3) Results: Erythrocytes caused significant cell death in 2D cultures (p < 0.001) and damaged 3D chondrocyte spheroids. Iron citrate and erythrocytes reduced chondrocyte DNA content (p < 0.001). The ferroptosis pathway was implicated in cell death, with no effects from apoptosis and necroptosis inhibitors. (4) Conclusions: This study offers insights into HA's cell death pathway, suggesting ferroptosis inhibitors as potential therapies. Further studies are needed to evaluate their efficacy against the chronic effects of HA.

Rethinking coagulation: from enzymatic cascade and cell-based reactions to a convergent model involving innate immune activation

ABSTRACT

Advancements in the conceptual thinking of hemostasis and thrombosis have been catalyzed by major developments within health research over several decades. The cascade model of coagulation was first described in the 1960s, when biochemistry gained prominence through innovative experimentation and technical developments. This was followed by the cell-based model, which integrated cellular coordination to the enzymology of clot formation and was conceptualized during the growth period in cell biology at the turn of the millennium. Each step forward has heralded a revolution in clinical therapeutics, both in procoagulant and anticoagulant treatments to improve patient care. In current times, the COVID-19 pandemic may also prove to be a catalyst: thrombotic challenges including the mixed responses to anticoagulant treatment and the vaccine-induced immune thrombotic thrombocytopenia have exposed limitations in our preexisting concepts while simultaneously demanding novel therapeutic approaches. It is increasingly clear that innate immune activation as part of the host response to injury is not separate but integrated into adaptive clot formation. Our review summarizes current understanding of the major molecules facilitating such a cross talk between immunity, inflammation and coagulation. We demonstrate how such effects can be layered upon the cascade and cell-based models to evolve conceptual understanding of the physiology of immunohemostasis and the pathology of immunothrombosis.

In vivo genome editing using 244-cis LNPs and low-dose AAV achieves therapeutic threshold in hemophilia A mice

Gene therapy and rebalancing therapy have emerged as promising approaches for treating hemophilia A, but there are limitations, such as temporary efficacy due to individual differences. Genome editing for hemophilia has shown long-term therapeutic potential in preclinical trials. However, a cautious approach is necessary because genome editing is irreversible. Therefore, we attempted to induce low-level human factor 8 (hF8) gene knockin (KI) using 244-cis lipid nanoparticles and low-dose adeno-associated virus to minimize side effects and achieve a therapeutic threshold in hemophilia A mice. We selected the serpin family C member 1, SerpinC1, locus as a target to enable a combined rebalancing strategy with hF8 KI to augment efficacy. This strategy improved blood coagulation activity and reduced hemophilic complications without adverse effects. Furthermore, hemophilic mice with genome editing exhibit enhanced survival for 40 weeks. Here, we demonstrate an effective, safe, and sustainable treatment for hemophilia A. This study provides valuable information to establish safe and long-term genome-editing-mediated treatment strategies for treating hemophilia and other protein-deficient genetic diseases.

Novel nomograms to predict risk and prognosis in hospitalized patients with severe fever with thrombocytopenia syndrome

Background

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging and life-threatening infectious disease caused by SFTS virus. Although recent studies have reported the use of nomograms based on demographic and laboratory data to predict the prognosis of SFTS, no study has included viral load, which is an important factor that influences the prognosis, when compared with other risk factors. Therefore, this study aimed to develop a model that predicts SFTS prognosis before it reaches the critical illness stage and to compare the predictive ability of groups with and without viral load.

Methods

Two hundred patients with SFTS were enrolled between June 2018 and August 2023. Data were sourced from the first laboratory results at admission, and two nomograms for mortality risk were developed using multivariate logistic regression to identify the risk variables for poor prognosis in these patients. We calculated the area under the receiver operating characteristic curve (AUC) for the two nomograms to assess their discrimination, and predictive abilities were compared using net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

Results

The multivariate logistic regression analysis identified four independent risk factors: age, bleeding manifestations, prolonged activated partial thromboplastin time, and viral load. Based on these factors, a final nomogram predicting mortality risk in patients with SFTS was constructed; in addition, a simplified nomogram was constructed excluding the viral load. The AUC [0.926, 95% confidence interval (CI): 0.882-0.970 vs. 0.882, 95% CI: 35 0.823-0.942], NRI (0.143, 95% CI, 0.036-0.285), and IDI (0.124, 95% CI, 0.061-0.186) were calculated and compared between the two models. The calibration curves of the two models showed excellent concordance, and decision curve analysis was used to quantify the net benefit at different threshold probabilities.

Conclusion

Two critical risk nomograms were developed based on the indicators for early prediction of mortality risk in patients with SFTS, and enhanced predictive accuracy was observed in the model that incorporated the viral load. The models developed will provide frontline clinicians with a convenient tool for early identification of critically ill patients and initiation of a better personalized treatment in a timely manner.

RNA Nanomedicine: Delivery Strategies and Applications

Delivery of RNA using nanomaterials has emerged as a new modality to expand therapeutic applications in biomedical research. However, the delivery of RNA presents unique challenges due to its susceptibility to degradation and the requirement for efficient intracellular delivery. The integration of nanotechnologies with RNA delivery has addressed many of these challenges. In this review, we discuss different strategies employed in the design and development of nanomaterials for RNA delivery. We also highlight recent advances in the pharmaceutical applications of RNA delivered via nanomaterials. Various nanomaterials, such as lipids, polymers, peptides, nucleic acids, and inorganic nanomaterials, have been utilized for delivering functional RNAs, including messenger RNA (mRNA), small interfering RNA, single guide RNA, and microRNA. Furthermore, the utilization of nanomaterials has expanded the applications of functional RNA as active pharmaceutical ingredients. For instance, the delivery of antigen-encoding mRNA using nanomaterials enables the transient expression of vaccine antigens, leading to immunogenicity and prevention against infectious diseases. Additionally, nanomaterial-mediated RNA delivery has been investigated for engineering cells to express exogenous functional proteins. Nanomaterials have also been employed for co-delivering single guide RNA and mRNA to facilitate gene editing of genetic diseases. Apart from the progress made in RNA medicine, we discuss the current challenges and future directions in this field.

Biodistribution of recombinant factor IX, extended half-life recombinant factor IX Fc fusion protein, and glycoPEGylated recombinant factor IX in hemophilia B mice

Extended half-life recombinant FIX (rFIX) molecules have been generated to reduce the dosing burden and increase the protection of patients with hemophilia B. Clinical pharmacology studies with recombinant factor IX Fc fusion protein (rFIXFc) report a similar initial peak plasma recovery to that of rFIX, but with a larger volume of distribution. Although the pegylation of N9-GP results in a larger plasma recovery, there is a smaller volume of distribution, suggesting less extravasation of the latter drug. In this study, we set out to compare the biodistribution and tissue localization of rFIX, rFIXFc, and glycoPEGylated rFIX in a hemophilia B mouse model. Radiolabeled rFIX, rFIXFc, and rFIX-GP were employed in in vivo single-photon emission computed tomography imaging (SPECT/CT), microautoradiography (MARG), and histology to assess the distribution of FIX reagents over time. Immediately following injection, vascularized tissues demonstrated intense signal irrespective of FIX reagent. rFIX and rFIXFc were retained in joint and muscle areas through 5 half-lives, unlike rFIX-GP (assessed by SPECT). MARG and immunohistochemistry showed FIX agents localized at blood vessels among tissues, including liver, spleen, and kidney. Microautoradiographs, as well as fluorescent-labeled images of knee joint areas, demonstrated retention over time of FIX signal at the trabecular area of bone. Data indicate that rFIXFc is similar to rFIX in that it distributes outside the plasma compartment and is retained in certain tissues over time, while also retained at higher plasma levels. Overall, data suggest that Fc fusion does not impede the extravascular distribution of FIX.

Recent Advances in Site-Specific Lipid Nanoparticles for mRNA Delivery

The success of mRNA vaccines during the COVID-19 pandemic has greatly accelerated the development of mRNA therapy. mRNA is a negatively charged nucleic acid that serves as a template for protein synthesis in the ribosome. Despite its utility, the instability of mRNA requires suitable carriers for in vivo delivery. Lipid nanoparticles (LNPs) are employed to protect mRNA from degradation and enhance its intracellular delivery. To further optimize the therapeutic efficacy of mRNA, site-specific LNPs have been developed. Through local or systemic administration, these site-specific LNPs can accumulate in specific organs, tissues, or cells, allowing for the intracellular delivery of mRNA to specific cells and enabling the exertion of local or systemic therapeutic effects. This not only improves the efficiency of mRNA therapy but also reduces off-target adverse effects. In this review, we summarize recent site-specific mRNA delivery strategies, including different organ- or tissue-specific LNP after local injection, and organ-specific or cell-specific LNP after intravenous injection. We also provide an outlook on the prospects of mRNA therapy.

Vagus nerve stimulation primes platelets and reduces bleeding in hemophilia A male mice

Deficiency of coagulation factor VIII in hemophilia A disrupts clotting and prolongs bleeding. While the current mainstay of therapy is infusion of factor VIII concentrates, inhibitor antibodies often render these ineffective. Because preclinical evidence shows electrical vagus nerve stimulation accelerates clotting to reduce hemorrhage without precipitating systemic thrombosis, we reasoned it might reduce bleeding in hemophilia A. Using two different male murine hemorrhage and thrombosis models, we show vagus nerve stimulation bypasses the factor VIII deficiency of hemophilia A to decrease bleeding and accelerate clotting. Vagus nerve stimulation targets acetylcholine-producing T lymphocytes in spleen and α7 nicotinic acetylcholine receptors (α7nAChR) on platelets to increase calcium uptake and enhance alpha granule release. Splenectomy or genetic deletion of T cells or α7nAChR abolishes vagal control of platelet activation, thrombus formation, and bleeding in male mice. Vagus nerve stimulation warrants clinical study as a therapy for coagulation disorders and surgical or traumatic bleeding.

In vivo genome editing for hemophilia B therapy by the combination of rebalancing and therapeutic gene knockin using a viral and non-viral vector

Recent therapeutic strategies for hemophilia include long-term therapeutic gene expression using adeno-associated virus (AAV) and rebalancing therapy via the downregulation of anticoagulant pathways. However, these approaches have limitations in immune responses or insufficiency to control acute bleeding. Thus, we developed a therapeutic strategy for hemophilia B by a combined rebalancing and human factor 9 (hF9) gene knockin (KI) using a lipid nanoparticle (LNP) and AAV. Antithrombin (AT; Serpin Family C Member 1 [Serpinc1]) was selected as the target anticoagulation pathway for the gene KI. First, the combined use of LNP-clustered regularly interspaced short palindromic repeats (CRISPR) and AAV donor resulted in 20% insertions or deletions (indels) in Serpinc1 and 67% reduction of blood mouse AT concentration. Second, hF9 coding sequences were integrated into approximately 3% of the target locus. hF9 KI yielded approximately 1,000 ng/mL human factor IX (hFIX) and restored coagulation activity to a normal level. LNP-CRISPR injection caused sustained AT downregulation and hFIX production up to 63 weeks. AT inhibition and hFIX protein-production ability could be maintained by the proliferation of genetically edited hepatocytes in the case of partial hepatectomy. The co-administration of AAV and LNP showed no severe side effects except random integrations. Our results demonstrate hemophilia B therapy by a combination of rebalancing and hF9 KI using LNP and AAV.

A graph-based machine learning framework identifies critical properties of FVIII that lead to hemophilia A

Introduction: Blood coagulation is an essential process to cease bleeding in humans and other species. This mechanism is characterized by a molecular cascade of more than a dozen components activated after an injury to a blood vessel. In this process, the coagulation factor VIII (FVIII) is a master regulator, enhancing the activity of other components by thousands of times. In this sense, it is unsurprising that even single amino acid substitutions result in hemophilia A (HA)-a disease marked by uncontrolled bleeding and that leaves patients at permanent risk of hemorrhagic complications. Methods: Despite recent advances in the diagnosis and treatment of HA, the precise role of each residue of the FVIII protein remains unclear. In this study, we developed a graph-based machine learning framework that explores in detail the network formed by the residues of the FVIII protein, where each residue is a node, and two nodes are connected if they are in close proximity on the FVIII 3D structure. Results: Using this system, we identified the properties that lead to severe and mild forms of the disease. Finally, in an effort to advance the development of novel recombinant therapeutic FVIII proteins, we adapted our framework to predict the activity and expression of more than 300 in vitro alanine mutations, once more observing a close agreement between the in silico and the in vitro results. Discussion: Together, the results derived from this study demonstrate how graph-based classifiers can leverage the diagnostic and treatment of a rare disease.

Building the foundation for a community-generated national research blueprint for inherited bleeding disorders: research priorities to transform the care of people with hemophilia

BACKGROUND

Decades of research have transformed hemophilia from severely limiting children's lives to a manageable disorder compatible with a full, active life, for many in high-income countries. The direction of future research will determine whether exciting developments truly advance health equity for all people with hemophilia (PWH). National Hemophilia Foundation (NHF) and American Thrombosis and Hemostasis Network conducted extensive inclusive all-stakeholder consultations to identify the priorities of people with inherited bleeding disorders and those who care for them.

RESEARCH DESIGN AND METHODS

Working group (WG) 1 of the NHF State of the Science Research Summit distilled the community-identified priorities for hemophilia A and B into concrete research questions and scored their feasibility, impact, and risk.

RESULTS

WG1 defined 63 top priority research questions concerning arthropathy/pain/bone health, inhibitors, diagnostics, gene therapy, the pediatric to adult transition of care, disparities faced by the community, and cardiovascular disease. This research has the potential to empower PWH to thrive despite lifelong comorbidities and achieve new standards of wellbeing, including psychosocial.

CONCLUSIONS

Collaborative research and care delivery will be key to capitalizing on current and horizon treatments and harnessing technical advances to improve diagnostics and testing, to advance health equity for all PWH.

The ethics of gene therapy for hemophilia: a narrative review

Gene therapy is expected to become a promising treatment, and potentially even a cure, for hemophilia. After several years of research, the first gene therapy product has been granted conditional market authorization by the European Union in August 2022. The recent progress in the field also has implications on the ethical aspects of hemophilia gene therapy. Reviews conducted in the 2000s mainly identified questions on the ethics of conducting early-phase clinical trials. However, since then, the knowledge on safety and efficacy has improved, and the field has moved toward clinical application, a phase that has its own ethical aspects. Therefore, we conducted a narrative review to take stock of the ethical aspects of hemophilia gene therapy. Based on our analysis of the literature, we identified 3 ethical themes. The theme Living up to expectations describes the existing hopes for gene therapy and the unlikelihood of the currently approved product becoming a permanent cure. In the theme Psychosocial impacts, we discuss the fear that gene therapy will impact the identity of people with hemophilia and their need for psychosocial support. The theme Costs and access discusses the expected cost-effectiveness of gene therapy and its implications on accessibility worldwide. We conclude that it may be necessary to change the narratives surrounding gene therapy, from describing it as a cure to describing it as one of the many treatments that temporarily relieve symptoms and that there is a need to reevaluate the desirability of gene therapy for hemophilia, given the availability of other treatments.

Protein Transduction Domain-Mediated Delivery of Recombinant Proteins and In Vitro Transcribed mRNAs for Protein Replacement Therapy of Human Severe Genetic Mitochondrial Disorders: The Case of Sco2 Deficiency

Mitochondrial disorders represent a heterogeneous group of genetic disorders with variations in severity and clinical outcomes, mostly characterized by respiratory chain dysfunction and abnormal mitochondrial function. More specifically, mutations in the human SCO2 gene, encoding the mitochondrial inner membrane Sco2 cytochrome c oxidase (COX) assembly protein, have been implicated in the mitochondrial disorder fatal infantile cardioencephalomyopathy with COX deficiency. Since an effective treatment is still missing, a protein replacement therapy (PRT) was explored using protein transduction domain (PTD) technology. Therefore, the human recombinant full-length mitochondrial protein Sco2, fused to TAT peptide (a common PTD), was produced (fusion Sco2 protein) and successfully transduced into fibroblasts derived from a SCO2/COX-deficient patient. This PRT contributed to effective COX assembly and partial recovery of COX activity. In mice, radiolabeled fusion Sco2 protein was biodistributed in the peripheral tissues of mice and successfully delivered into their mitochondria. Complementary to that, an mRNA-based therapeutic approach has been more recently considered as an innovative treatment option. In particular, a patented, novel PTD-mediated IVT-mRNA delivery platform was developed and applied in recent research efforts. PTD-IVT-mRNA of full-length SCO2 was successfully transduced into the fibroblasts derived from a SCO2/COX-deficient patient, translated in host ribosomes into a nascent chain of human Sco2, imported into mitochondria, and processed to the mature protein. Consequently, the recovery of reduced COX activity was achieved, thus suggesting the potential of this mRNA-based technology for clinical translation as a PRT for metabolic/genetic disorders. In this review, such research efforts will be comprehensibly presented and discussed to elaborate their potential in clinical application and therapeutic usefulness.

Real-World Use of Albutrepenonacog Alfa, A Recombinant Coagulation Factor IX Albumin Fusion Protein, for Personalized Prophylaxis in Japanese Individuals With Hemophilia B: A Case Series

Currently, the mainstay of disease management for hemophilia B, a hemorrhagic disease caused by a congenital deficiency or molecular abnormalities of blood coagulation factor IX (FIX), is prophylaxis using FIX concentrate. On-demand injections of FIX concentrate may also be required, even during prophylaxis, when a patient with hemophilia B is bleeding. Albutrepenonacog alfa (rFIX-FP) is a human albumin fusion gene recombinant FIX, which is administered once every seven, 14, or 21 days, depending on patient preferences and symptoms. Studies have demonstrated its efficacy and safety in a range of patients; however, to date, reports of real-world experiences of the use of rFIX-FP in Japan are limited. We present a case series of three Japanese individuals with moderately severe (FIX activity 1 to <2%) or severe (FIX activity <1%) hemophilia B who benefited from prophylaxis using rFIX-FP in our clinical practice setting. We highlighted the good effectiveness of rFIX-FP in a patient with moderately severe hemophilia B who required prophylaxis due to joint bleeding, which was causing deterioration of his left ankle joint, as well as in a patient with severe hemophilia B and atherothrombotic cerebral infarction, whose trough level had to be ≥5% for concomitant use of an antiplatelet drug, and in a patient with severe hemophilia B who was working in nursing care, which involved heavy labor and night shifts, and who had previously been treated with on-demand FIX concentrate. In all three cases, rFIX-FP improved disease symptoms, and the patients were able to maintain steady states of therapy due to the treatment characteristics of rFIX-FP, which stabilizes FIX at high trough levels.

A Patient with Severe Fever with Thrombocytopenia Syndrome, Activated Partial Thromboplastin Time Prolongation, and Transient Antiphospholipid Antibodies

A prolonged activated partial thromboplastin time (APTT) is observed in patients with severe fever with thrombocytopenia syndrome (SFTS) and is one of the risk factors for severe disease. The mechanism underlying a prolonged APTT is largely unknown. The presence of antiphospholipid (aPL) antibodies in various viral infections has been documented but never reported in a patient with SFTS. We herein report the first SFTS patient with APTT prolongation and concurrent transiently positive aPL antibodies (lupus anticoagulants and anticardiolipin antibodies) with no coagulation factor deficiency.

Early stage clinical trials for the treatment of hemophilia A

INTRODUCTION

Hemophilia A is a severe bleeding disorder affecting about 1 in 5,000 males. The gold standard for prophylaxis and treatment of acute bleeding has been factor (F) VIII concentrate. A multitude of treatment modalities are now available and under clinical investigation.

AREAS COVERED

This review discusses ongoing/recently completed early-phase clinical trials registered on ClinicalTrials.gov in patients with hemophilia A through April 2022. These new pipeline therapies are focused on addressing the safety and efficacy of new factor-related products, non-factor related products, and gene therapy options for hemophilia.

EXPERT OPINION

Current standard of care effectively prevents and treats acute bleeding and has significantly improved the quality of life in hemophilia. The biggest challenges in the improvement of care are treatment-related burden and the burden of cost in developing countries. New drugs under development are likely to enter practice by the end of this decade and address many of the unmet needs particularly of those with severe disease. Data is limited in unique populations (e.g. congenital/inherited FVIII inhibitors, non-severe hemophilia A, women/girls with hemophilia and children) which are important areas for future research; additional clinical trials and long-term outcome data are necessary prior to incorporating these new therapies in our treatment arsenal.

Computational Analyses Reveal Fundamental Properties of the Hemophilia Literature in the Last 6 Decades

Hemophilia is an inherited blood coagulation disorder caused by mutations on the coagulation factors VIII or IX genes. Although it is a relatively rare disease, the research community is actively working on this topic, producing almost 6000 manuscripts in the last 5 years. Given that the scientific literature is increasing so rapidly, even the most avid reader will find it difficult to follow it closely. In this study, we used sophisticated computational techniques to map the hemophilia literature of the last 60 years. We created a network structure to represent authorship collaborations, where the nodes are the researchers and 2 nodes are connected if they co-authored a manuscript. We accurately identified author clusters, namely, researchers who have collaborated systematically for several years, and used text mining techniques to automatically synthesize their research specialties. Overall, this study serves as a historical appreciation of the effort of thousands of hemophilia researchers and demonstrates that a computational framework is able to automatically identify collaboration networks and their research specialties. Importantly, we made all datasets and source code available for the community, and we anticipate that the methods introduced here will pave the way for the development of systems that generate compelling hypothesis based on patterns that are imperceptible to human researchers.

Treatment Individualization Using Pharmacokinetic Studies and Joint Ultrasound Imaging in Pediatric Patients With Hemophilia

Hemophilia is characterized by bleeding diathesis, primarily affecting the joints. Prophylactic use of missing factor aims at limiting the number of bleeds and, in the long term, the risk of permanent joint damage. However, standard prophylactic regimens are usually applied empirically, not adjusting for variations in bleeding phenotype or drug metabolism. Aim of the present study was to evaluate the need for individualizing prophylaxis, with guidance of pharmacokinetic (PK) studies and joint ultrasound in a setting of everyday clinical practice. To evaluate adequacy of applied regimens, joint status was assessed using the Hemophilia Joint Health Score as well as ultrasound imaging, while PK studies were performed using the Web-Accessible Population Pharmacokinetic Service-Hemophilia. Imaging results were consistent with early joint damage in a large proportion of pediatric patients, whereas PK measures were indicative of inadequate prophylaxis in many cases-despite the limited number of bleeds reported by patients. The study revealed the need for prophylaxis adjustment in the majority of patients. Real world data confirm that traditional prophylaxis is often unable to achieve therapeutic goals, while an individualized approach, guided by the use of novel modalities, may be of great benefit to young hemophilia patients.

First study of extended half-life rFVIIIFc in previously untreated patients with hemophilia A: PUPs A-LONG final results

PUPs A-LONG evaluated the safety and efficacy of recombinant factor VIII Fc fusion protein (rFVIIIFc) in previously untreated patients (PUPs) with hemophilia A. This open-label, phase 3 study enrolled male PUPs (<6 years) with severe hemophilia A to receive rFVIIIFc. The primary endpoint was the occurrence of inhibitor development. Secondary endpoints included annualized bleed rate (ABR). Of 103 subjects receiving ≥1 dose of rFVIIIFc, 80 (78%) were aged <1 year at the study start, 20 (19%) had a family history of inhibitors, and 82 (80%) had high-risk F8 mutations. Twenty subjects began on prophylaxis, while 81 began an on-demand regimen (69 later switched to prophylaxis). Eighty-seven (81%) subjects completed the study. Inhibitor incidence was 31.1% (95% confidence interval [CI], 21.8% to 41.7%) in subjects with ≥10 exposure days (or inhibitor); high-titer inhibitor incidence was 15.6% (95% CI, 8.8% to 24.7%). The median (range) time to high-titer inhibitor development was 9 (4-14) exposure days. Twenty-eight (27%) subjects experienced 32 rFVIIIFc treatment-related adverse events; most were inhibitor development. There was 1 nontreatment-related death due to intracranial hemorrhage (onset before the first rFVIIIFc dose). The overall median (interquartile range [IQR]) ABR was 1.49 (0.00-4.40) for subjects on variable prophylaxis dosing regimens. In this study of rFVIIIFc in pediatric PUPs with severe hemophilia A, overall inhibitor development was within the expected range, although high-titer inhibitor development was on the low end of the range reported in the literature. rFVIIIFc was well-tolerated and effective for prophylaxis and treatment of bleeds. This trial is registered at www.clinicaltrials.gov (NCT02234323).

Polymer-drug conjugates: Design principles, emerging synthetic strategies and clinical overview

Adagen, an enzyme replacement treatment for adenosine deaminase deficiency, was the first protein-polymer conjugate to be approved in early 1990s. Post this regulatory approval, numerous polymeric drugs and polymeric nanoparticles have entered the market as advanced or next-generation polymer-based therapeutics, while many others have currently been tested clinically. The polymer conjugation to therapeutic moiety offers several advantages, like enhanced solubilization of drug, controlled release, reduced immunogenicity, and prolonged circulation. The present review intends to highlight considerations in the design of therapeutically effective polymer-drug conjugates (PDCs), including the choice of linker chemistry. The potential synthetic strategies to formulate PDCs have been discussed along with recent advancements in the different types of PDCs, i.e., polymer-small molecular weight drug conjugates, polymer-protein conjugates, and stimuli-responsive PDCs, which are under clinical/preclinical investigation. Current impediments and regulatory hurdles hindering the clinical translation of PDC into effective therapeutic regimens for the amelioration of disease conditions have been addressed.

Liver-directed lentiviral gene therapy corrects hemophilia A mice and achieves normal-range factor VIII activity in non-human primates

Liver gene therapy with adeno-associated viral (AAV) vectors delivering clotting factor transgenes into hepatocytes has shown multiyear therapeutic benefit in adults with hemophilia. However, the mostly episomal nature of AAV vectors challenges their application to young pediatric patients. We developed lentiviral vectors, which integrate in the host cell genome, that achieve efficient liver gene transfer in mice, dogs and non-human primates, by intravenous delivery. Here we first compare engineered coagulation factor VIII transgenes and show that codon-usage optimization improved expression 10-20-fold in hemophilia A mice and that inclusion of an unstructured XTEN peptide, known to increase the half-life of the payload protein, provided an additional >10-fold increase in overall factor VIII output in mice and non-human primates. Stable nearly life-long normal and above-normal factor VIII activity was achieved in hemophilia A mouse models. Overall, we show long-term factor VIII activity and restoration of hemostasis, by lentiviral gene therapy to hemophilia A mice and normal-range factor VIII activity in non-human primate, paving the way for potential clinical application.

“Lentiviral gene therapy to the liver establishes stable long-term normal to supra-normal coagulation factor VIII activity in mouse models of hemophilia A and in non-human primates, representing a potential new treatment option for people with hemophilia A.”.

Managing Severe Hemophilia A in Children: Pharmacotherapeutic Options

Hemophilia A is the most common severe inherited bleeding disorder in males. Initial treatment strategies focused on the use of factor concentrates to prevent joint bleeding and the development of long-term crippling arthropathy. The current standard of care has evolved from regular replacement of factor VIII concentrates which has significantly improved the quality of life for those with severe disease to include and consider novel therapies that augment or bypass the hemostatic pathway (ie, emicizumab, Mim8). Other pipeline therapies that suppress specific natural anticoagulant pathways (ie, antithrombin, TFPI) to reestablish hemostatic balance are under Phase 3 trial investigation. These novel therapeutics have allowed providers more variety in dosing regimens and ease of administration while also maintaining effective bleeding prevention. The possibility of "curative" gene therapy is under exploration, with ongoing clinical trials in adult males.

Modeling Benefits, Costs, and Affordability of a Novel Gene Therapy in Hemophilia A

The objective was to undertake an early cost-effectiveness assessment of valoctocogene roxaparvovec (valrox; Roctavian) compared to factor (F)VIII prophylaxis or emicizumab (Hemlibra; Roche HQ, Bazel, Switzerland) in patients with severe Hemophilia A (HA) without FVIII-antibodies. We also aimed to incorporate and quantify novel measures of value such as treatment durability, maximum value-based price (MVBP) and break-even time (ie, time until benefits begin to offset upfront payment). We constructed a Markov model to model bleeds over time which were linked to costs and quality-of-life decrements. In the valrox arm, FVIII over time was estimated combining initial effect and treatment waning and then linked to bleeds. In FVIII and emicizumab arms, bleeds were based on trial evidence. Evidence and assumptions were validated using expert elicitation. Model robustness was tested via sensitivity analyses. A Dutch societal perspective was applied with a 10-year time horizon. Valrox in comparison to FVIII, and emicizumab showed small increases in quality-adjusted life years at lower costs, and were therefore dominant. Valrox' base case MVBP was estimated at €2.65 million/treatment compared to FVIII and €3.5 million/treatment versus emicizumab. Mean break-even time was 8.03 years compared to FVIII and 5.68 years to emicizumab. Early modeling of patients with HA in The Netherlands treated with valrox resulted in estimated improved health and lower cost compared to prophylactic FVIII and emicizumab. We also demonstrated feasibility of incorporation of treatment durability and novel outcomes such as value-based pricing scenarios and break-even time. Future work should aim to better characterize uncertainties and increase translation of early modeling to direct research efforts.

In vivo delivery of CRISPR-Cas9 using lipid nanoparticles enables antithrombin gene editing for sustainable hemophilia A and B therapy

Hemophilia is a hereditary disease that remains incurable. Although innovative treatments such as gene therapy or bispecific antibody therapy have been introduced, substantial unmet needs still exist with respect to achieving long-lasting therapeutic effects and treatment options for inhibitor patients. Antithrombin (AT), an endogenous negative regulator of thrombin generation, is a potent genome editing target for sustainable treatment of patients with hemophilia A and B. In this study, we developed and optimized lipid nanoparticles (LNPs) to deliver Cas9 mRNA along with single guide RNA that targeted AT in the mouse liver. The LNP-mediated CRISPR-Cas9 delivery resulted in the inhibition of AT that led to improvement in thrombin generation. Bleeding-associated phenotypes were recovered in both hemophilia A and B mice. No active off-targets, liver-induced toxicity, and substantial anti-Cas9 immune responses were detected, indicating that the LNP-mediated CRISPR-Cas9 delivery was a safe and efficient approach for hemophilia therapy.

Development of alternative gene transfer techniques for ex vivo and in vivo gene therapy in a canine model

INTRODUCTION

Gene therapy have recently attracted much attention as a curative therapeutic option for inherited single gene disorders such as hemophilia. Hemophilia is a hereditary bleeding disorder caused by the deficiency of clotting activity of factor VIII (FVIII) or factor IX (FIX), and gene therapy for hemophilia using viral vector have been vigorously investigated worldwide. Toward further advancement of gene therapy for hemophilia, we have previously developed and validated the efficacy of novel two types of gene transfer technologies using a mouse model of hemophilia A. Here we investigated the efficacy and safety of the technologies in canine model. Especially, validations of technical procedures of the gene transfers for dogs were focused.

METHODS

Green fluorescence protein (GFP) gene were transduced into normal beagle dogs by ex vivo and in vivo gene transfer techniques. For ex vivo gene transfer, blood outgrowth endothelial cells (BOECs) derived from peripheral blood of normal dogs were transduced with GFP gene using lentivirus vector, propagated, fabricated as cell sheets, then implanted onto the omentum of the same dogs. For in vivo gene transfer, normal dogs were subjected to GFP gene transduction with non-viral piggyBac vector by liver-targeted hydrodynamic injections.

RESULTS

No major adverse events were observed during the gene transfers in both gene transfer systems. As for ex vivo gene transfer, histological findings from the omental biopsy performed 4 weeks after implantation revealed the tube formation by implanted GFP-positive BOECs in the sub-adipose tissue layer without any inflammatory findings, and the detected GFP signals were maintained over 6 months. Regarding in vivo gene transfer, analyses of liver biopsy samples revealed more than 90% of liver cells were positive for GFP signals in the injected liver lobes 1 week after gene transfers, then the signals gradually declined overtime.

CONCLUSIONS

Two types of gene transfer techniques were successfully applied to a canine model, and the transduced gene expressions persisted for a long term. Toward clinical application for hemophilia patients, practical assessments of therapeutic efficacy of these techniques will need to be performed using a dog model of hemophilia and FVIII (or FIX) gene.

Recent advances in lentiviral vectors for gene therapy

Lentiviral vectors (LVs), derived from human immunodeficiency virus, are powerful tools for modifying the genes of eukaryotic cells such as hematopoietic stem cells and neural cells. With the extensive and in-depth studies on this gene therapy vehicle over the past two decades, LVs have been widely used in both research and clinical trials. For instance, third-generation and self-inactive LVs have been used to introduce a gene with therapeutic potential into the host genome and achieve targeted delivery into specific tissue. When LVs are employed in leukemia, the transduced T cells recognize and kill the tumor B cells; in β-thalassemia, the transduced CD34⁺ cells express normal β-globin; in adenosine deaminase-deficient severe combined immunodeficiency, the autologous CD34⁺ cells express adenosine deaminase and realize immune reconstitution. Overall, LVs can perform significant roles in the treatment of primary immunodeficiency diseases, hemoglobinopathies, B cell leukemia, and neurodegenerative diseases. In this review, we discuss the recent developments and therapeutic applications of LVs. The safe and efficient LVs show great promise as a tool for human gene therapy.

Efficacy, safety, and immunogenicity of rurioctocog alfa pegol for prophylactic treatment in previously treated patients with severe hemophilia A: a systematic review and meta-analysis of clinical trials

Background: Patients with severe hemophilia often present with painful joint and soft tissue bleeding which may restrict them from their daily activities. The current standard of care still relies on a regular prophylactic factor VIII (FVIII), which has a high daily treatment burden. Recently, rurioctocog alfa pegol, a third-generation recombinant FVIII with a modification in its polyethylene glycol (PEG) component, has been developed. Several trials have studied this synthetic drug as bleeding prophylaxis in severe hemophilia A. This study aims to evaluate the efficacy, safety, and immunogenicity of rurioctocog alfa pegol for previously treated patients with severe hemophilia A. Methods: This study was conducted in conformity with the PRISMA guidelines. Data were retrieved from PubMed, Scopus, Cochrane Library, Wiley Online Library, and CINAHL (via EBSCOhost). Study qualities were assessed using the Methodological Index for Non-Randomized Studies (MINORS) and Modified Jadad scales. Results: Four studies involving 517 previously treated severe hemophilia A patients were included in this study. The pooled mean of total annualized bleeding rate (ABR) and hemostatic efficacy was 2.59 (95% CI = 2.04-3.14) and 92% (95% CI = 85%-97%), respectively. Only 30 (2.3%) non-serious and one (1.4%) serious adverse events were considered related to rurioctocog alfa pegol treatment. At the end of the studies, no development of FVIII inhibitory antibodies was observed. None of the developed binding antibodies to FVIII, PEG-FVIII, or PEG was correlated to the treatment efficacy and safety. Conclusions: Despite the limited availability of direct comparison studies, our analyses indicate that rurioctocog alfa pegol could serve as a safe and effective alternative for bleeding prophylaxis in previously treated hemophilia A patients. Moreover, it appears to have low immunogenicity, which further increases the safety profile of the drug in such clinical conditions.

Efficacy, safety, and immunogenicity of rurioctocog alfa pegol for prophylactic treatment in previously treated patients with severe hemophilia A: a systematic review and meta-analysis of clinical trials

Background: Patients with severe hemophilia often present with painful joint and soft tissue bleeding which may restrict them from their daily activities. The current standard of care still relies on a regular prophylactic factor VIII (FVIII), which has a high daily treatment burden. Recently, rurioctocog alfa pegol, a third-generation recombinant FVIII with a modification in its polyethylene glycol (PEG) component, has been developed. Several trials have studied this synthetic drug as bleeding prophylaxis in severe hemophilia A. This study aims to evaluate the efficacy, safety, and immunogenicity of rurioctocog alfa pegol for previously treated patients with severe hemophilia A. Methods: This study was conducted in conformity with the PRISMA guidelines. Data were retrieved from PubMed, Scopus, Cochrane Library, Wiley Online Library, and CINAHL (via EBSCOhost). Study qualities were assessed using the Methodological Index for Non-Randomized Studies (MINORS) and Modified Jadad scales. Results: Four studies involving 517 previously treated severe hemophilia A patients were included in this study. The pooled mean of total annualized bleeding rate (ABR) and hemostatic efficacy was 2.59 (95% CI = 2.04-3.14) and 92% (95% CI = 85%-97%), respectively. Only 30 (2.3%) non-serious and one (1.4%) serious adverse events were considered related to rurioctocog alfa pegol treatment. At the end of the studies, no development of FVIII inhibitory antibodies was observed. None of the developed binding antibodies to FVIII, PEG-FVIII, or PEG was correlated to the treatment efficacy and safety. Conclusions: Despite the limited availability of direct comparison studies, our analyses indicate that rurioctocog alfa pegol could serve as a safe and effective alternative for bleeding prophylaxis in previously treated hemophilia A patients. Moreover, it appears to have low immunogenicity, which further increases the safety profile of the drug in such clinical conditions.

Efficacy safety and immunogenicity of rurioctocog alfa pegol for prophylactic treatment in previously treated patients with severe hemophilia A: a systematic review and meta-analysis of clinical trials

Background: Patients with severe hemophilia often present with painful joint and soft tissue bleeding which may restrict them from their daily activities. The current standard of care still relies on a regular prophylactic factor VIII (FVIII), which has a high daily treatment burden. Recently, rurioctocog alfa pegol, a third-generation recombinant FVIII with a modification in its polyethylene glycol (PEG) component, has been developed. Several trials have studied this synthetic drug as bleeding prophylaxis in severe hemophilia A. This study aims to evaluate the efficacy, safety, and immunogenicity of rurioctocog alfa pegol for previously treated patients with severe hemophilia A. Methods: This study was conducted in conformity with the PRISMA guidelines. Data were retrieved from PubMed, Scopus, Cochrane Library, Wiley Online Library, and CINAHL (via EBSCOhost). Study qualities were assessed using the Methodological Index for Non-Randomized Studies (MINORS) and Modified Jadad scales. Results: Four studies involving 517 previously treated severe hemophilia A patients were included in this study. The pooled mean of total annualized bleeding rate (ABR) and hemostatic efficacy was 2.59 (95% CI = 2.04-3.14) and 92% (95% CI = 85%-97%), respectively. Only 30 (2.3%) non-serious and one (1.4%) serious adverse events were considered related to rurioctocog alfa pegol treatment. At the end of the studies, no development of FVIII inhibitory antibodies was observed. None of the developed binding antibodies to FVIII, PEG-FVIII, or PEG was correlated to the treatment efficacy and safety. Conclusions: Despite the limited availability of direct comparison studies, our analyses indicate that rurioctocog alfa pegol could serve as a safe and effective alternative for bleeding prophylaxis in previously treated hemophilia A patients. Moreover, it appears to have low immunogenicity, which further increases the safety profile of the drug in such clinical conditions.

Novel Severe Hemophilia A Mouse Model with Factor VIII Intron 22 Inversion

Simple Summary

Recently, innovative gene therapy has been developing toward functional restoration by gain of function or gene correction. Hemophilia is a representative genetic disorder with many human patients and is considered a candidate disease for gene therapy. The most frequent severe hemophilia A is caused by inversion mediated structural variation of the human F8 gene. Nevertheless, a mouse model with F8 intron 22 inversion is not developed yet. This study presents a novel hemophilia A mouse model with 319 kb inversion and severe coagulation disorder and could be utilized in future gene correction preclinical trials.

Abstract

Hemophilia A (HA) is an X-linked recessive blood coagulation disorder, and approximately 50% of severe HA patients are caused by F8 intron 22 inversion (F8I22I). However, the F8I22I mouse model has not been developed despite being a necessary model to challenge pre-clinical study. A mouse model similar to human F8I22I was developed through consequent inversion by CRISPR/Cas9-based dual double-stranded breakage (DSB) formation, and clinical symptoms of severe hemophilia were confirmed. The F8I22I mouse showed inversion of a 391 kb segment and truncation of mRNA transcription at the F8 gene. Furthermore, the F8I22I mouse showed a deficiency of FVIII activity (10.9 vs. 0 ng/mL in WT and F8I22I, p < 0.0001) and severe coagulation disorder phenotype in the activated partial thromboplastin time (38 vs. 480 s, p < 0.0001), in vivo bleeding test (blood loss/body weight; 0.4 vs. 2.1%, p < 0.0001), and calibrated automated thrombogram assays (Thrombin generation peak, 183 vs. 21.5 nM, p = 0.0012). Moreover, histological changes related to spontaneous bleeding were observed in the liver, spleen, and lungs. We present a novel HA mouse model mimicking human F8I22I. With a structural similarity with human F8I22I, the F8I22I mouse model will be applicable to the evaluation of general hemophilia drugs and the development of gene-editing-based therapy research.

Final results of the PUPs B-LONG study: evaluating safety and efficacy of rFIXFc in previously untreated patients with hemophilia B

PUPs B-LONG evaluated the safety and efficacy of recombinant factor IX Fc fusion protein (rFIXFc) in previously untreated patients (PUPs) with hemophilia B. In this open-label, phase 3 study, male PUPs (age <18 years) with hemophilia B (≤2 IU/dL of endogenous factor IX [FIX]) were to receive treatment with rFIXFc. Primary end point was occurrence of inhibitor development, with a secondary end point of annualized bleed rate (ABR). Of 33 patients who received ≥1 dose of rFIXFc, 26 (79%) were age <1 year at study entry and 6 (18%) had a family history of inhibitors. Twenty-eight patients (85%) received prophylaxis; median dosing interval was 7 days, with an average weekly dose of 58 IU/kg. Twenty-seven patients (82%) completed the study. Twenty-one (64%), 26 (79%), and 28 patients (85%) had ≥50, ≥20, and ≥10 exposure days (EDs) to rFIXFc, respectively. One patient (3.03%; 95% confidence interval, 0.08% to 15.76%) developed a low-titer inhibitor after 11 EDs; no high-titer inhibitors were detected. Twenty-three patients (70%) had 58 treatment-emergent serious adverse events; 2 were assessed as related (FIX inhibition and hypersensitivity in 1 patient, resulting in withdrawal). Median ABR was 1.24 (interquartile range, 0.00-2.49) for patients receiving prophylaxis. Most (>85%) bleeding episodes required only 1 infusion for bleed resolution. In this first study reporting results with rFIXFc in pediatric PUPs with hemophilia B, rFIXFc was well tolerated, with the adverse event profile as expected in a pediatric hemophilia population. rFIXFc was effective, both as prophylaxis and in the treatment of bleeding episodes. This trial was registered at www.clinicaltrials.gov as #NCT02234310.

Recombinant sclerostin inhibits bone formation in vitro and in a mouse model of sclerosteosis

Background

Sclerosteosis, a severe autosomal recessive sclerosing skeletal dysplasia characterised by excessive bone formation, is caused by absence of sclerostin, a negative regulator of bone formation that binds LRP5/6 Wnt co-receptors. Current treatment is limited to surgical management of symptoms arising from bone overgrowth. This study investigated the effectiveness of sclerostin replacement therapy in a mouse model of sclerosteosis.

Methods

Recombinant wild type mouse sclerostin (mScl) and novel mScl fusion proteins containing a C-terminal human Fc (mScl hFc), or C-terminal human Fc with a poly-aspartate motif (mScl hFc PD), were produced and purified using mammalian expression and standard chromatography methods. In vitro functionality and efficacy of the recombinant proteins were evaluated using three independent biophysical techniques and an in vitro bone nodule formation assay. Pharmacokinetic properties of the proteins were investigated in vivo following a single administration to young female wild type (WT) or SOST knock out (SOST^-/-) mice. In a six week proof-of-concept in vivo study, young female WT or SOST^-/- mice were treated with 10 mg/kg mScl hFc or mScl hFc PD (weekly), or 4.4 mg/kg mScl (daily). The effect of recombinant sclerostin on femoral cortical and trabecular bone parameters were assessed by micro computed tomography (μCT).

Results

Recombinant mScl proteins bound to the extracellular domain of the Wnt co-receptor LRP6 with high affinity (nM range) and completely inhibited matrix mineralisation in vitro. Pharmacokinetic assessment following a single dose administered to WT or SOST^-/- mice indicated the presence of hFc increased protein half-life from less than 5 min to at least 1.5 days. Treatment with mScl hFc PD over a six week period resulted in modest but significant reductions in trabecular volumetric bone mineral density (vBMD) and bone volume fraction (BV/TV), of 20% and 15%, respectively.

Conclusion

Administration of recombinant mScl hFc PD partially corrected the high bone mass phenotype in SOST^-/- mice, suggesting that bone-targeting of sclerostin engineered to improve half-life was able to negatively regulate bone formation in the SOST^-/- mouse model of sclerosteosis.

The translational potential of this article

These findings support the concept that exogenous sclerostin can reduce bone mass, however the modest efficacy suggests that sclerostin replacement may not be an optimal strategy to mitigate excessive bone formation in sclerosteosis, hence alternative approaches should be explored.

Prediction of hemophilia A severity using a small-input machine-learning framework

Hemophilia A is a relatively rare hereditary coagulation disorder caused by a defective F8 gene resulting in a dysfunctional Factor VIII protein (FVIII). This condition impairs the coagulation cascade, and if left untreated, it causes permanent joint damage and poses a risk of fatal intracranial hemorrhage in case of traumatic events. To develop prophylactic therapies with longer half-lives and that do not trigger the development of inhibitory antibodies, it is essential to have a deep understanding of the structure of the FVIII protein. In this study, we explored alternative ways of representing the FVIII protein structure and designed a machine-learning framework to improve the understanding of the relationship between the protein structure and the disease severity. We verified a close agreement between in silico, in vitro and clinical data. Finally, we predicted the severity of all possible mutations in the FVIII structure – including those not yet reported in the medical literature. We identified several hotspots in the FVIII structure where mutations are likely to induce detrimental effects to its activity. The combination of protein structure analysis and machine learning is a powerful approach to predict and understand the effects of mutations on the disease outcome.

Coagulation factor IX analysis in bioreactor cell culture supernatant predicts quality of the purified product

Coagulation factor IX (FIX) is a complex post-translationally modified human serum glycoprotein and high-value biopharmaceutical. The quality of recombinant FIX (rFIX), especially complete γ-carboxylation, is critical for rFIX clinical efficacy. Bioreactor operating conditions can impact rFIX production and post-translational modifications (PTMs). With the goal of optimizing rFIX production, we developed a suite of Data Independent Acquisition Mass Spectrometry (DIA-MS) proteomics methods and used these to investigate rFIX yield, γ-carboxylation, other PTMs, and host cell proteins during bioreactor culture and after purification. We detail the dynamics of site-specific PTM occupancy and structure on rFIX during production, which correlated with the efficiency of purification and the quality of the purified product. We identified new PTMs in rFIX near the GLA domain which could impact rFIX GLA-dependent purification and function. Our workflows are applicable to other biologics and expression systems, and should aid in the optimization and quality control of upstream and downstream bioprocesses.

Molecular determinants of the factor VIII/von Willebrand factor complex revealed by BIVV001 cryo-electron microscopy

Interaction of factor VIII (FVIII) with von Willebrand factor (VWF) is mediated by the VWF D'D3 domains and thrombin-mediated release is essential for hemostasis after vascular injury. VWF-D'D3 mutations resulting in loss of FVIII binding are the underlying cause of von Willebrand disease (VWD) type 2N. Furthermore, the FVIII-VWF interaction has significant implications for the development of therapeutics for bleeding disorders, particularly hemophilia A, in which endogenous VWF clearance imposes a half-life ceiling on replacement FVIII therapy. To understand the structural basis of FVIII engagement by VWF, we solved the structure of BIVV001 by cryo-electron microscopy to 2.9 Å resolution. BIVV001 is a bioengineered clinical-stage FVIII molecule for the treatment of hemophilia A. In BIVV001, VWF-D'D3 is covalently linked to an Fc domain of a B domain-deleted recombinant FVIII (rFVIII) Fc fusion protein, resulting in a stabilized rFVIII/VWF-D'D3 complex. Our rFVIII/VWF structure resolves BIVV001 architecture and provides a detailed spatial understanding of previous biochemical and clinical observations related to FVIII-VWF engagement. Notably, the FVIII acidic a3 peptide region (FVIII-a3), established as a critical determinant of FVIII/VWF complex formation, inserts into a basic groove formed at the VWF-D'/rFVIII interface. Our structure shows direct interaction of sulfated Y1680 in FVIII-a3 and VWF-R816 that, when mutated, leads to severe hemophilia A or VWD type 2N, respectively. These results provide insight on this key coagulation complex, explain the structural basis of many hemophilia A and VWD type 2N mutations, and inform studies to further elucidate how VWF dissociates rapidly from FVIII upon activation.