Current and future therapies for haemophilia-Beyond factor replacement therapies

Emicizumab promotes factor Xa generation on endothelial cells

BACKGROUND

Until recently, the treatment of hemophilia A relied on factor (F)VIII replacement. However, up to one-third of patients with severe hemophilia A develop neutralizing alloantibodies that render replacement therapies ineffective. The development of emicizumab, a bispecific antibody that partially mimics FVIIIa, has revolutionized the treatment of these patients. However, the use of an activated prothrombin complex concentrate [FEIBA (Takeda)] to treat breakthrough bleeding in patients on emicizumab has been associated with thrombotic complications including a unique microangiopathy.

OBJECTIVES

We hypothesized that the thrombotic complications observed with the combination of emicizumab and FEIBA might be due to excessive expression of procoagulant activity on the surface of endothelial cells.

METHODS

We examined the ability of emicizumab to promote FX activation on endothelial cells using 2 cell culture models.

RESULTS

We found that endothelial cells readily support emicizumab-mediated activation of FX by FIXa. The level of FXa generation depends on the concentration of available FIXa. The addition of FEIBA to emicizumab increased FXa generation in a dose-dependent manner on endothelial cells in both models. The rate of FXa generation was further enhanced by endothelial cell activation. However, unlike emicizumab, we found limited FXa generation in the presence of FVIII(a), which followed a significant lag time and was not dependent on FIXa concentration under these conditions.

CONCLUSION

Emicizumab promotes FXa generation on the surface of endothelial cells, which is markedly enhanced in the presence of FEIBA. These findings demonstrate a potential mechanism for the thrombotic complications seen with the combined use of emicizumab and FEIBA.

The effects of emicizumab on in vitro coagulation and fibrinolysis parameters in patients with disseminated intravascular coagulation with and without addition of anti-FVIII antibody

BACKGROUND

Emicizumab (Emi) is used as haemostatic prophylaxis for patients with haemophilia A (PwHA). Disseminated intravascular coagulation (DIC) is a condition characterized by persistent systemic activation of coagulation, but there is yet no information on coagulation and fibrinolysis potentials in Emi-treated PwHA with DIC.

AIM

To examine the effect of Emi on coagulation and fibrinolysis potentials in HA-model DIC plasmas.

METHODS

Plasma from a patient with sepsis-DIC (seven patients) was treated with anti-factor (F)VIII monoclonal antibody (HA-model DIC plasma) and incubated with Emi (50 µg/mL). The plasma was then assessed using clot-fibrinolysis waveform analysis (CFWA). Coagulation and fibrinolysis parameters were expressed as ratios relative to normal plasma (|min1|-ratio and |FL-min1|-ratio, respectively).

PATIENTS AND RESULTS

In case 1, coagulant potential was slightly high and fibrinolytic potential was extremely low, presenting a coagulant-dominant state (|min1|-ratio/|FL-min1|-ratio: 1.1/.38). In cases 2-5, fibrinolytic potential was not suppressed, but there were marked hypercoagulant potentials, indicating relative coagulant-dominant states. In case 6, coagulant and fibrinolytic potentials were increased but well balanced (|min1|-ratio/|FL-min1|-ratio: 1.38/1.28). In case 7, both potentials were severely deteriorated in not only CFWA but also the thrombin/plasmin generation assay. The addition of Emi into the HA-model DIC plasmas increased |min1|-ratio values in all cases, but the coagulant potentials did not exceed the initial ones (DIC plasma before treatment with anti-FVIII antibody).

CONCLUSIONS

The presence of Emi in the HA-model DIC plasma improved coagulation potentials, but did not increase coagulation potentials beyond those of DIC plasma in non-HA states.

A small-molecule hemostatic agent for the reversal of direct oral anticoagulant-induced bleeding

Background

The bleeding risk associated with direct oral anticoagulants (DOACs) remains a major concern, and rapid reversal of anticoagulant activity may be required. Although specific and nonspecific hemostatic biotherapies are available, there is a need for small-molecule DOAC reversal agents that are simple and cost-effective to produce, store, and administer.

Objectives

To identify and characterize a small molecule with procoagulant activity as a DOAC reversal agent.

Methods

We sought to identify a small procoagulant molecule by screening a chemical library with a plasma clotting assay. The selected molecule was assessed for its procoagulant properties and its ability to reverse the effects of the DOACs in a thrombin generation assay. Its activity as a DOAC reversal agent was also evaluated in a tail-clip bleeding assay in mice.

Results

The hemostatic molecule (HeMo) dose-dependently promoted thrombin generation in plasma, with dose values effective in producing half-maximum response ranging between 3 and 5 μM, depending on the thrombin generation assay parameter considered. HeMo also restored impaired thrombin generation in DOAC-spiked plasma and reversed DOAC activity in the mouse bleeding model. HeMo significantly reduced apixaban-induced bleeding from 709 to 65 μL (vs 43 μL in controls; P < .01) and dabigatran-induced bleeding from 989 to 155 μL (vs 126 μL in controls; P < .01).

Conclusion

HeMo is a small-molecule procoagulant that can counterbalance hemostatic disruption by a thrombin inhibitor (dabigatran) or factor Xa inhibitors (apixaban and rivaroxaban). The compound's effective clot formation and versatility make it a possible option for managing the inherent hemorrhagic risk during DOAC therapy.

Deciphering conundrums of adeno-associated virus liver-directed gene therapy: focus on hemophilia

Adeno-associated virus gene therapy has been the subject of intensive investigation for monogenic disease gene addition therapy for more than 25 years, yet few therapies have been approved by regulatory agencies. Most have not progressed beyond phase 1/2 due to toxicity, lack of efficacy, or both. The liver is a natural target for adeno-associated virus since most serotypes have a high degree of tropism for hepatocytes due to cell surface receptors for the virus and the unique liver sinusoidal geometry facilitating high volumes of blood contact with hepatocyte cell surfaces. Recessive monogenic diseases such as hemophilia represent promising targets since the defective proteins are often synthesized in the liver and secreted into the circulation, making them easy to measure, and many do not require precise regulation. Yet, despite initiation of many disease-specific clinical trials, therapeutic windows are often nonexistent, resulting in excess toxicity and insufficient efficacy. Iterative progress built on these attempts is best illustrated by hemophilia, with the first regulatory approvals for factor IX and factor VIII gene therapies eventually achieved 25 years after the first gene therapy studies in humans. Although successful gene transfer may result in the production of sufficient transgenic protein to modify the disease, many emerging questions on durability, predictability, reliability, and variability of response have not been answered. The underlying biology accounting for these heterogeneous responses and the interplay between host and virus is the subject of intense investigation and the subject of this review.

Ultra-Long factor VIII: a major step forward toward a hemophilia-free mind

A remarkable step forward in the treatment of hemophilia A has recently been achieved with the development of an Ultra-Long modified factor (F)VIII. Leveraging expertise gained with fusion to immunoglobulin Fc fragments, disconnecting FVIII from endogenous von Willebrand factor (via a D'-D3 fragment), and benefiting from the pharmacokinetic prolongation provided by the addition of hydrophilic polypeptides, efanesoctocog alfa opens a new era in the treatment of hemophilia A. The term Ultra-Long FVIII has been proposed to designate it and differentiate it from extended half-life FVIII. The level of FVIII correction within the normal range for several days provided by this molecule should allow an increasing number of patients to free themselves from the physical and psychological constraints of hemophilia A. Certainly, the burden of weekly intravenous infusions persists but is compensated by a correction of hemostasis whose amplitude and duration remain unmatched by other therapeutic options currently available.

Factor XI deficiency: phenotypic age-related considerations and clinical approach towards bleeding risk assessment

ABSTRACT

Factor XI (FXI) deficiency is a rare bleeding disorder that presents complex challenges in patient assessment and bleeding risk management. Despite generally causing mild to moderate bleeding symptoms, clinical manifestations can vary, and bleeding tendency does not always correlate with FXI plasma levels or genotype. Our manuscript delves into the age-related nuances of FXI deficiency across an individual's lifespan. We emphasize issues faced by specific groups, including neonates and females of reproductive age experiencing abnormal uterine bleeding and postpartum hemorrhage. Older patients present unique challenges and concerns related to the management of bleeding as well as thrombotic complications. The current assortment of diagnostic laboratory assays shows limited success in predicting bleeding risk in the perisurgical setting of patients with FXI deficiency. This review explores the intricate interplay between individual bleeding profiles, surgical sites, and FXI activity levels. We also evaluate the accuracy of existing laboratory assays in predicting bleeding and discuss the potential role of investigational global assays in perioperative assessment. Furthermore, we outline our suggested diagnostic approach to refine treatment strategies and decision making. Available treatment options are presented, including antifibrinolytics, replacement products, and recombinant activated FVII. Finally, we discuss promising nonreplacement therapies for the treatment of rare bleeding disorders that can potentially address the challenges faced when managing FXI deficiency-related bleeding complications.

The underevaluated impacts of the therapeutic revolution of hemophilia on women and girls

The advent of new treatment options over the last decades has markedly improved the lives of male persons with hemophilia (PwH). However, this therapeutic revolution has not benefited women and girls with hemophilia (WGH) and symptomatic carriers of the disease to the same extent as their male counterparts. This inequity is primarily due to the exclusion of WGH from clinical trials and a failure to fully recognize their specific treatment needs. Additionally, the indirect impact of innovative therapies, when used for male PwH, on the lives of mothers, other relatives, and partners of these individuals has been largely overlooked until now. In addition to improving access of WGH and carriers to new hemostatic treatments and comprehensive hemophilia care, it is imperative to strive for alleviating the mental burden imposed on them by this chronic disease. The recently proposed concept of a "hemophilia-free mind," primarily focused on male PwH, should therefore also be applied to WGH, symptomatic carriers, and the predominantly female support network of PwH.

Six-Year, Real-World Use of Prophylaxis with Recombinant Factor IX-Albumin Fusion Protein (rIX-FP) in Persons with Hemophilia B: A Single-Center Retrospective-Prospective Study

Background: Extended half-life (EHL) factor IX (FIX) concentrates allow for prophylaxis with prolonged dosing intervals and high bleeding protection in persons with hemophilia B. Long-term real-world studies are lacking. Methods: In a retrospective-prospective study, the six-year use of prophylaxis with the EHL recombinant FIX-albumin fusion protein (rIX-FP) was analyzed, comparing outcomes with previous standard half-life (SHL) FIX in patients already on prophylaxis. Results: Prophylaxis with rIX-FP was prescribed in 15 patients (10 severe, 5 moderate; follow-up: 57 ± 17 months). Based on a pharmacokinetic assessment and clinical needs, the first regimen was 47 ± 7 IU/Kg every 9 ± 2 days. All but one patient remained on rIX-FP prophylaxis, adjusting infusion frequency and/or dose; the last prescribed frequency was ≥10 days in 10/13 patients, being reduced in seven and increased in four vs. the first regimen. The weekly FIX dose was unchanged; FIX trough levels were >5% in all patients. The annual infusion number and FIX IU/Kg significantly decreased (~60%) in eight patients previously on SHL FIX prophylaxis, with similar concentrate costs. Very low bleeding rates (most traumatic bleeds and the last quartile of the infusion interval), improved orthopedic and pain scores, unchanged HEAD-US scores and problem joints, and high treatment adherence (>90%) and satisfaction were registered. Conclusions: Personalized, carefully adjusted rIX-FP regimens contribute to the diffusion and optimization of prophylaxis in persons with severe and moderate hemophilia B, with long-term favorable bleeding, joint, and patient-reported outcomes.

Recapitulating the immune system of hemophilia A patients with inhibitors using immunodeficient mice

BACKGROUND AND AIM

Treating hemophilia A patients who develop inhibitors remains a clinical challenge. A mouse model of hemophilia A can be used to test the efficacy of strategies for inhibitor suppression, but the differences in the immune systems of mice and humans limit its utility. To address this shortcoming, we established a humanized NOD/SCID-IL2rγnull hemophilia A (hu-NSG-HA) mouse model with a severely deficient mouse immune system presenting a patient's adapted immune cells.

METHODS AND RESULTS

Through intrasplenic injection with patient inhibitor-positive peripheral blood mononuclear cells (PBMCs), utilizing an adeno-associated viral delivery system expressing human BLyS, and regular FVIII challenge, human C19+ B cells were expanded in vivo to secrete anti-FVIII antibodies. Both the inhibitor and the human anti-FVIII IgG, including the predominant subclasses (IgG1 and IgG4) present in the majority of inhibitor patients, were detected in the mouse model. We further segregated and expanded the different clones of human anti-FVIII-secreting cells through subsequent transplantation of splenocytes derived from hu-NSG-HA mice into another NSG-HA mouse. By transplanting a patient's PBMCs into the NSG-HA mouse model, we demonstrated the success of reintroducing a strong anti-FVIII immune response for a short period in mice with the immune systems of inhibitor-positive patients.

CONCLUSION

Our results demonstrate a potential tool for directly obtaining functional human-derived antigen-specific antibodies and antibody-secreting cells, which may have therapeutic value for testing patient-specific immune responses to treatment options to assist in clinical decisions.

Perspectives and perception of haemophilia gene therapy by French patients

INTRODUCTION AND AIM

A national survey was initiated by representatives of French patients with haemophilia (AFH) and the French reference centre for haemophilia, in order to appreciate the awareness and knowledge of these patients regarding haemophilia gene therapy (HGT) and understand better their position about this innovative treatment that will soon become available.

RESULTS

Of 143 answers received, 137 could be analysed, representing about 3.5% of patients with severe or moderate haemophilia over 16year-old. They were 80.3% with haemophilia A and 19.7 % with haemophilia B, with a severe form of the disease for 80.3 % of them. Curiosity for HGT was formulated by 64.2% of the participants, 33.6 % being interested by this approach as soon as it will be available and 38.7 % preferring to wait until more patients have been treated. Only 3.6 % of the participants would never consider receiving HGT. The level of awareness and knowledge was estimated to be limited by 39.5 % of the patients. More than 60 % of them declared having never or almost never discussed HGT with the team of their haemophilia centre. Before deciding to get HGT, 54.4 % of the participants considered that it will be very important to compare it with their current treatment and 53.7 % would like to be better informed by their care providers.

CONCLUSIONS

These results highlight the need for training and education for patients, but also for professionals at haemophilia centres, about HGT and the shared decision-making process. Objective, unbiased and transparent information must be available for patients about this very promising therapy which nonetheless carries more uncertainty and unknowns compared to other haemophilia treatments.

Targeting the Liver with Nucleic Acid Therapeutics for the Treatment of Systemic Diseases of Liver Origin

Systemic diseases of liver origin (SDLO) are complex diseases in multiple organ systems, such as cardiovascular, musculoskeletal, endocrine, renal, respiratory, and sensory organ systems, caused by irregular liver metabolism and production of functional factors. Examples of such diseases discussed in this article include primary hyperoxaluria, familial hypercholesterolemia, acute hepatic porphyria, hereditary transthyretin amyloidosis, hemophilia, atherosclerotic cardiovascular diseases, α-1 antitrypsin deficiency-associated liver disease, and complement-mediated diseases. Nucleic acid therapeutics use nucleic acids and related compounds as therapeutic agents to alter gene expression for therapeutic purposes. The two most promising, fastest-growing classes of nucleic acid therapeutics are antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs). For each listed SDLO disease, this article discusses epidemiology, symptoms, genetic causes, current treatment options, and advantages and disadvantages of nucleic acid therapeutics by either ASO or siRNA drugs approved or under development. Furthermore, challenges and future perspectives on adverse drug reactions and toxicity of ASO and siRNA drugs for the treatment of SDLO diseases are also discussed. In summary, this review article will highlight the clinical advantages of nucleic acid therapeutics in targeting the liver for the treatment of SDLO diseases. SIGNIFICANCE STATEMENT: Systemic diseases of liver origin (SDLO) contain rare and common complex diseases caused by irregular functions of the liver. Nucleic acid therapeutics have shown promising clinical advantages to treat SDLO. This article aims to provide the most updated information on targeting the liver with antisense oligonucleotides and small interfering RNA drugs. The generated knowledge may stimulate further investigations in this growing field of new therapeutic entities for the treatment of SDLO, which currently have no or limited options for treatment.

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.

Emicizumab prophylaxis for people with hemophilia A: Waste estimation and the Brazilian perspective

Costs of hemophilia A treatment are increasing. Waste of clotting products should be avoided. To estimate the first-year waste of emicizumab prophylaxis for people with hemophilia A and inhibitors (PwHAi) who failed immune tolerance induction (ITI), in Brazil. We evaluated the manufacturer and the Brazilian Ministry of Health (MoH) protocol-recommended regimens in a budget impact model. The loading dose consisted of 3.0 mg/kg/Q1W for 4 weeks, for both recommendations. The manufacturer maintenance regimens comprised 1.5 mg/kg/Q1W, 3.0 mg/kg/Q2W, and 6.0 mg/kg/Q4W. The MoH protocol maintenance regimen encompassed a hybrid Q1W/Q2W administration, depending on the body weight. The Q4W regimen was not recommended by the MoH protocol. Analyses were performed to estimate waste given its expense based on the World Health Organization body weight range (percentiles [P] 15, 50, and 85). The first-year emicizumab waste was estimated individually and for the disclosed PwHAi who failed ITI (n = 114). The highest emicizumab waste was estimated for the lowest body weights and the Q1W regimen. The Q4W regimen resulted in the lowest emicizumab waste, followed by the MoH protocol regimen. The total reconstituted costs estimated for the PwHAi who failed ITI according to the hybrid MoH protocol ranged from US$32,858,777 (P15) to US$47,186,858 (P85), with emicizumab waste ranging from 7.9 % (US$2,594,515) to 3.7 % (US$1,738,750), respectively. Lost resources due to current protocols for emicizumab prophylaxis for PwHAi who failed ITI in Brazil are considerable. Waste was more pronounced due to lower body weight and shorter administration intervals.

Emergent data influences the risk/benefit assessment of hemophilia gene therapy using recombinant adeno-associated virus

After decades of investigation, gene therapy has received regulatory approval to treat hemophilia. However, since gene therapy investigations were initially conceived, other avenues of treatment have revolutionized the care of hemophilia. Emergent data is showing that gene therapy may not be as beneficial as hoped and more toxic than planned. At a minimum, a reassessment of risk/benefit estimate of gene therapy for hemophilia is needed.

The Evaluation of Clot Waveform Analyses for Assessing Hypercoagulability in Patients Treated with Factor VIII Concentrate

BACKGROUND

Regular prophylactic therapy has become an increasingly common treatment for severe hemophilia. Therefore, hypercoagulability-a potential risk factor of thrombosis-is a cause for concern in hemophilic patients treated with a high dose of FVIII concentrate. In clot waveform analysis (CWA)-thrombin time (TT), a small amount of thrombin activates clotting factor VIII (FVIII) instead of fibrinogen, resulting in FVIII measurements using CWA-TT with a small amount of thrombin.

METHODS

The coagulation ability of patients treated with FVIII concentrate or emicizumab was evaluated using activated partial thromboplastin time (APTT), TT and a small amount of tissue factor-induced FIX activation assay (sTF/FIXa) using CWA.

RESULTS

The FVIII activity based on CWA-TT was significantly greater than that based on the CWA-APTT or chromogenic assay. FVIII or FVIII-like activities based on the three assays in plasma without emicizumab were closely correlated; those in plasma with emicizumab based on CWA-TT and chromogenic assays were also closely correlated. CWA-APTT and CWA-TT showed different patterns in patients treated with FVIII concentrates compared to those treated with emicizumab. In particular, CWA-TT in patients treated with FVIII concentrate showed markedly higher peaks in platelet-rich plasma than in platelet-poor plasma. CWA-APTT showed lower coagulability in hemophilic patients treated with FVIII concentrate than in healthy volunteers, whereas CWA-sTF/FIXa did not. In contrast, CWA-TT showed hypercoagulability in hemophilic patients treated with FVIII concentrate.

CONCLUSIONS

CWA-TT can be used to evaluate the thrombin bursts that cause hypercoagulability in patients treated with emicizumab. Although routine APTT evaluations demonstrated low coagulation ability in patients treated with FVIII concentrate, CWA-TT showed hypercoagulability in these patients, suggesting that the evaluation of coagulation ability may be useful when using multiple assays.

Hemophilic arthropathy: how to diagnose subclinical bleeding early and how to orthopedically treat a damaged joint

INTRODUCTION

It is important to know the current status of hemophilic arthropathy diagnoses, treatments, complications, and outcomes in developed countries.

AREAS COVERED

A bibliographic search in PubMed for articles published from 1 January 2019 through 12 June 2023 was performed.

EXPERT OPINION

In developed countries with specialized hemophilia treatment centers, primary hematological prophylaxis (started before the age of 2 years and after no more than one joint bleed) has almost completely eliminated the joint-related problems of the disease. The ideal goal of zero hemarthroses can be achieved only with intense and well-dosed prophylaxis: intravenous infusion of coagulation factor - standard half-life or extended half-life; periodic or subcutaneous injections of nonfactor products (emicizumab or fitusiran). However, hemophilic arthropathy continues to occur due to subclinical joint hemorrhages. In one study, 16% of the joints without reported hemarthroses showed signs of previous subclinical bleeding (hemosiderin deposits with/without synovial hypertrophy on magnetic resonance imaging were deemed signs of previous subclinical bleeding), rendering evidence for subclinical bleeding in people with severe hemophilia with lifelong prophylaxis treatment. Subclinical joint hemorrhages can be averted only by employing accurate and tailored prophylaxis.

The role of intraarticular injections of hyaluronic acid in joint pain relief in hemophilic arthropathy

INTRODUCTION

Chronic pain in hemophilic patients is due to joint degeneration associated with hemophilic arthropathy. In addition to appropriate hematological treatment (primary prophylaxis), pharmacologic management and Physical Medicine and Rehabilitation should be indicated. When such measures are not sufficient, intraarticular injections (IAIs) of hyaluronic acid (HyA) may be considered.

AREAS COVERED

In order to determine whether IAIs of HyA are effective in terms of pain relief in individuals with painful moderate hemophilic arthropathy, a PubMed and Cochrane Library search using 'hemophilia hyaluronic acid' as keywords was performed on 18 July 2023.

EXPERT OPINION

In a study of individuals with hemophilic arthropathy (elbows, knees and ankles), 91% of them improved pain after a mean follow-up of 6 years. In another study of individuals with knee arthropathy, after a 7-year follow-up 82% reported an improvement in pain. As for hemophilic ankle arthropathy, in a study 67% of patients showed relief of joint pain at 6-month follow-up. Although the literature on the subject is very heterogeneous and difficult to interpret, it appears that IAIs of HyA can relieve the joint pain of painful moderate hemophilic arthropathy for months. Moreover, the IAIs can be repeated every 6-12 months.

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.

Haemophilia and Fragility Fractures: From Pathogenesis to Multidisciplinary Approach

Haemophilia A (HA) and haemophilia B (HB) are X-linked inherited bleeding disorders caused by the absence or deficiency of coagulation factors VIII (FVIII) and IX (FIX), respectively. Recent advances in the development of effective treatments for haemophilia have led to a significant increase in life expectancy. As a result, the incidence of some comorbidities, including fragility fractures, has increased in people with haemophilia (PWH). The aim of our research was to perform a review of the literature investigating the pathogenesis and multidisciplinary management of fractures in PWH. The PubMed, Scopus and Cochrane Library databases were searched to identify original research articles, meta-analyses, and scientific reviews on fragility fractures in PWH. The mechanism underlying bone loss in PWH is multifactorial and includes recurrent joint bleeding, reduced physical activity with consequent reduction in mechanical load, nutritional deficiencies (particularly vitamin D), and FVIII and FIX deficiency. Pharmacological treatment of fractures in PWH includes antiresorptive, anabolic and dual action drugs. When conservative management is not possible, surgery is the preferred option, particularly in severe arthropathy, and rehabilitation is a key component in restoring function and maintaining mobility. Appropriate multidisciplinary fracture management and an adapted and tailored rehabilitation pathway are essential to improve the quality of life of PWH and prevent long-term complications. Further clinical trials are needed to improve the management of fractures in PWH.

Bispecific antibodies mimicking factor VIII in hemophilia A: converting innovation to an essential medicine

Preventive subcutaneous treatment of severe hemophilia A with bispecific antibodies that mimic the action of coagulation factor VIII (FVIII) is emerging as an effective alternative to replacement therapy with intravenous administration of FVIII concentrates, either derived from plasma or produced by biotechnology. Access to this innovative therapeutic approach for a growing number of patients worldwide increasingly appears to be a priority public health strategy. Inclusion of FVIII mimetic bispecific antibodies on the World Health Organization essential medicines list would contribute to health equity in lower-income countries.

Synovitis in hemophilia: preventing, detecting, and treating joint bleeds

INTRODUCTION

Most bleeding events in individuals with hemophilia occur within the ankle, knee, and elbow joints. Should the bleeding persist, the synovial membrane starts to hypertrophy and a vicious cycle of chronic hemophilic synovitis (CHS) occurs, leading to joint destruction.

AREAS COVERED

This article covers the prompt diagnosis of CHS by point-of-care ultrasonography (POC-US) and its treatment by means of several types of synovectomy.

EXPERT OPINION

It is essential to prevent, detect and treat hemophilic synovitis, because it indicates that the joint has bled and is at risk of bleeding further. Prophylaxis with standard half life (SHL) factor VIII (FVIII) concentrate is the standard of care for individuals with severe hemophilia A and can also be considered for selected patients with moderate disease. Several years of real-world experience with extended half life (EHL) FVIII, emicizumab, and other drugs in development will be needed to ascertain their final effect on bleeding and its complications. We must look for synovitis in individuals declaring joint pain and in asymptomatic patients, and POC-US is the most reasonable imaging instrument with which to carry out periodic joint screening. Radiosynovectomy, chemical synovectomy, and arthroscopic synovectomy markedly reduce bleeding events.