Severe Von Willebrand Disease Research Articles

Cost-effectiveness of prophylaxis with recombinant vs plasma-derived VWF in severe von Willebrand disease in the United States

AbstractWe evaluated the cost-effectiveness of prophylaxis with recombinant von Willebrand factor (rVWF) vs with plasma-derived von Willebrand factor (pdVWF) for patients with severe Von Willebrand disease. We found that rVWF is a cost-saving factor replacement compared with pdVWF across all willingness-to-pay thresholds in the United States.

Von Willebrand factor/factor VIII concentrate (Wilate) prophylaxis in children and adults with von Willebrand disease

AbstractLong-term prophylaxis with a von Willebrand factor (VWF) concentrate is recommended in patients with von Willebrand disease (VWD) who have a history of severe and frequent bleeds. However, data from prospective studies are scarce. WIL-31, a prospective, noncontrolled, international phase 3 trial, investigated the efficacy and safety of Wilate prophylaxis in severe patients with VWD. Male and female patients 6 years or older with VWD types 1, 2 (except 2N), or 3 who had completed a prospective, 6-month, on-demand, run-in study (WIL-29) were eligible to receive Wilate prophylaxis for 12 months. At baseline, patients (n = 33) had a median age of 18 years. Six (18%) patients had severe type 1, 5 (15%) had type 2, and 22 (67%) had type 3 VWD. The primary end point of a >50% reduction in mean total annualized bleeding rate (TABR) with Wilate prophylaxis vs prior on-demand treatment was met; mean TABR during prophylaxis was 5.2, representing an 84.4% reduction. The bleeding reduction was consistent across age, sex, and VWD types. The mean spontaneous ABR was 3.2, representing an 86.9% reduction vs on-demand treatment. During prophylaxis, 10 (30.3%) patients had 0 bleeding events and 15 (45.5%) patients had 0 spontaneous bleeding events. Of 173 BEs, 84.4% were minor and 69.9% treated. No serious adverse events related to study treatment and no thrombotic events were recorded. Overall, WIL-31 showed that Wilate prophylaxis was efficacious and well-tolerated in pediatric and adult patients with VWD of all types. The WIL-29 and WIL-31 trials were registered at www.ClinicalTrials.gov as #NCT04053699 and #NCT04052698, respectively.

Real-World Use of Recombinant Von Willebrand Factor in People with Clinically Severe Congenital Von Willebrand Disease: Interim Analysis of Athn 9: A Natural History Study for People with Severe VWD

Background: People with von Willebrand disease (VWD) present with a spectrum of bleeding patterns and clinical symptoms, independent of subtype (Rugeri. Haematologica. 2007; Kalot. Haemophilia. 2021). In certain situations, prophylaxis may be appropriate, particularly when there is recurrent and severe bleeding (Connell, Blood Advances, 2021). There are limited real-world data on the use of recombinant von Willebrand factor (rVWF) in the United States. Aim: To characterize the safety and real-world effectiveness of routine prophylaxis with rVWF in people with clinically severe congenital VWD. Study Design and Methods:This is an interim analysis of a phase 4, longitudinal, prospective, observational cohort study (NCT03853486). Participants with severe VWD types 1, 2, and 3 (≤30% of normal) or “clinically severe VWD” (≤40% of normal with severe bleeding and requiring prophylaxis with factor concentrates) were identified from the ATHNdataset. The American Thrombosis & Hemostasis Network (ATHN) is the steward of the ATHNdataset, a Health Insurance Portability and Accountability Act-compliant, de-identified patient health dataset containing data from individuals with bleeding disorders receiving care through ATHN affiliates who opt in to contribute. Treatment regimens were at the discretion of each participant's respective bleeding disorder provider. Participants are followed for 2 years from the time of enrollment. Safety was measured using definitions from the European Haemophilia Safety Surveillance program. Bleeding events (BEs) were measured by individual bleeding components and calculated per the International Society on Thrombosis and Haemostasis Bleed Assessment Tool and/or the Pictorial Bleeding Assessment Chart. Health-related quality of life measures, including an ATHN9 rVWF substudy form, were used to describe real-world effectiveness of rVWF treatment. Descriptive statistics were used to analyze study outcomes. This study was not designed to detect differences in safety or efficacy between individual treatment products. Interim Results:As of June 16, 2023, 23 participants enrolled in the ATHN9 study were receiving rVWF; 14 participants have been prescribed rVWF for at least 1 full year, 13 of whom received continuous prophylaxis. This abstract reports on those 13 participants in the first year of the study. Mean (SD) age was 42.9 (29.2) years; 69.2% (n=9) of participants were female. Most participants had no comorbidities. As expected, most participants had a family history of VWD (84.6%; n=11) and no documented VWF inhibitors (84.6%; n=11); inhibitor status for the remaining 2 participants was unknown. Baseline VWF and factor VIII measurements were reported for most participants ( Table 1). The majority had type 2 VWD (84.6%; n=11), 92.3% (n=12) had identifiable genetic sequence defects in VWF, and 30.8% (n=4) had an abnormal VWF multimer profile. As dictated by the local investigator, rVWF prophylactic regimens ranged from 36.6 IU/kg once weekly to 57.6 IU/kg every 3 days; 7 (53.8%) participants received 40-60 IU/kg at a frequency of 2-3 times per week. Twenty-one BEs occurred in 5 (38.5%) of the participants receiving rVWF prophylaxis during the first year ( Table 2). Most BEs were spontaneous (61.9%; 13/21), occurring in the nose (n=7), gastrointestinal tract (n=5), or ankle (n=1). The remaining BEs were associated with activity with no known trauma (n=4), trauma (n=2), or unknown cause (n=2). One participant reported 3 rVWF treatment-unrelated adverse events (AEs) of humerus shaft closed fracture, metabolic encephalopathy, and acute exacerbation of chronic obstructive airways disease. When surveyed about their experience with rVWF, participants reported very or extremely satisfied as follows: 76.9% (n=10) with infusion time, 84.6% (n=11) with breakthrough bleed control time, 46.2% (n=6) with number of infusions required for breakthrough bleed control, and 69.2% (n=9) with frequency of achieving bleed control without concomitant hemostatic medication. Discussion:In participants with clinically severe congenital VWD, continuous prophylaxis with rVWF was associated with minimal AEs. Most participants receiving rVWF prophylaxis experienced no BEs during the first year of the study. Most participants expressed overall satisfaction with the use of rVWF.

Cost-Effectiveness of Long-Term Prophylaxis with Plasma-Derived Vs. Recombinant Von Willebrand Factor in Severe Von Willebrand Disease

Introduction: von Willebrand disease (VWD) is the most common inherited bleeding disorder and exhibits significant variability in bleeding phenotype across patients. International guidelines conditionally recommend long-term prophylaxis to reduce bleeding events for patients with a severe phenotype: all patients with type 3 VWD and a subset of patients with severe phenotypes of types 1 and 2 VWD. At the time of this conditional recommendation, only 10% of patients with severe VWD are treated prophylactically, unlike patients with severe hemophilia (~45%). In the United States, there are currently two approved factor replacement therapies: plasma-derived von Willebrand factor (pdVWF) and recombinant von Willebrand factor (rVWF). The cost-effectiveness of prophylaxis options for patients with VWD in the United States is not known. We sought to fill this gap by determining the cost-effectiveness of pdVWF versus rVWF prophylaxis treatment options for patients with severe VWD. Methods: In this independent analysis free of industry influence, we constructed a Markov model of adult patients with severe VWD to compare the cost-effectiveness of long-term prophylaxis with pdVWF versus rVWF. Transition probabilities for patients' breakthrough bleeding events while on prophylaxis with each factor replacement product, and product utilization, were derived from an open-label, prospective, phase 3 clinical trial that employed a pdVWF versus rVWF switch design (NCT 02973087). Costs of prophylaxis and costs of VWD-specific breakthrough bleed health resource utilization in the United States (US) accounted for bleed category, severity, and bleed-specific mortality, and were sourced from previously published literature and the Centers for Medicare & Medicaid Services. For effectiveness measured in quality-adjusted life-years (QALY), utilities for patients with severe VWD on prophylaxis were informed from EQ-5D-specific utility data for patients with severe hemophilia on prophylaxis. The primary outcome was the incremental cost-effectiveness ratio (ICER) or the incremental net monetary benefit (iNMB) if the intervention (rVWF) was found to be cost-saving, reported over a lifetime time-horizon across a range of accepted willingness-to-pay (WTP) thresholds in US dollars per QALY. The two secondary outcomes were threshold analyses for 1) the breakthrough bleed rate and 2) frequency of infusions necessary for the non-favored product (i.e., in the base-case) to become favored. In addition, we conducted a scenario analysis assuming the non-significant reduction in bleeding with rVWF (0.55 [95% confidence interval 0.086-3.523]) otherwise nullified in the base-case analysis, was significant. We proceeded with deterministic sensitivity analyses, varying all parameter estimates across the largest of their known 95% confidence intervals or +/-20% of absolute value. We concluded with a probabilistic sensitivity analysis, capturing uncertainty in all parameters simultaneously over 10,000 Monte Carlo simulations. Results: In the base-case, treatment with prophylactic pdVWF versus prophylactic rVWF yielded discounted lifetime costs of $21.2 million and $19.8 million, with both accruing 20.6 discounted QALYs. The average incremental net monetary benefit across accepted WTP thresholds of $50,000-$150,000/QALY was $1.38 million [95% credible interval $1.10-1.67 million], in favor of rVWF. Deterministic sensitivity analysis showed that the model was most sensitive to the frequency and cost of pdVWF infusions. In all three probabilistic sensitivity analyses across all WTP thresholds, rVWF was favored over pdVWF in 100% of 10,000 Monte Carlo iterations. Threshold analyses revealed that 1) the bleeding rate on pdVWF prophylaxis would have to reduce by at least 43% and, 2) the average frequency of pdVWF infusions would need to decrease from 3 to 2.75 infusions per week for pdVWF to be favored over rVWF prophylaxis. Scenario analysis revealed similar significant improvement in incremental net monetary benefit with rVWF. Conclusion: Twice-weekly rVWF versus thrice-weekly pdVWF demonstrated similar quality-adjusted life-expectancy, while rVWF was cost-saving due to its longer half-life requiring fewer lifetime infusions. At current pricing in the United States, prophylactic rVWF is a cost-saving option for patients averaging more than 2.75 weekly pdVWF infusions.

Characterization and Quantification of Von Willebrand Factor Proteoforms in Von Willebrand Disease Patients and Healthy Controls: Insights from the Win-Study

Background: Von Willebrand disease (VWD) is a commonly inherited bleeding disorder which is characterized by either low (type 1) or absent (type 3) levels of Von Willebrand factor (VWF) or by the occurrence of dysfunctional VWF proteoforms (type 2) in plasma. The complexity of diagnosing and managing VWD arises from limited understanding of the diverse VWF proteoforms present in both healthy individuals as well as in VWD patients. Objective: The aim of this study was to investigate the plasma proteome and to characterize VWF proteoforms in Von Willebrand disease (VWD) patients, that were enrolled in the Willebrand in the Netherlands (WiN) 1 study, compared with healthy controls. Method: We selected type 1, type 2A, type 2M, type 2N and type 3 patients from the WiN cohort for which extensive laboratory- and genotype data were available. Plasma from 64 VWD patients and ten healthy controls was analyzed using a combination of discovery- and targeted mass spectrometry-based approaches. Results: Both discovery-based as well as targeted quantitative proteomics analysis revealed significant variation in VWF levels across the selected VWD patient group, which was in line with reported clinical laboratory data. Elevated VWF-propeptide/VWF ratios were observed in plasma samples from a range of VWD patients, with notable increases observed in VWD type 2A, B, and M, indicating accelerated clearance of these VWF proteoforms. Discovery-based proteomics revealed a strong VWF-F8 relationship in all VWD subtypes and healthy controls, except for type 2N VWD. We were able to identify peptides corresponding with common polymorphisms ( e.g. p.Thr798Ala, p.Gln852Arg, p.Thr1381Ala), for which the observed peptide distribution was in line with the minor allele frequency reported by the Broad institute. In addition, we identified peptides corresponding with 16 pathogenic VWF variants (e.g. p.Arg1306Trp, p. Phe1293Leu, p.Cys1190Arg, p.Arg1374His or p.Tyr1584Cys) of which p.Cys1190Arg wild-type and variant peptide aligned with the zygosity at DNA level (Figure X). Based on spike-in with stable isotope-labeled peptides, the variant-to-wildtype ratios varied among VWD patients with distinct pathogenic variants, ranging from 0.5-2.5 in type 2M (p.Phe1293Leu) and type 1 patients (p.Tyr1584Cys), <1 in type 2A patients (p.Arg1374His), to >8 in type 2B patients (p.Arg1306Trp), suggesting distinct stoichiometry of VWF variants among these patients (Figure 2). Conclusion: Our study highlights the feasibility of VWF proteoform identification and quantification from plasma and suggest a potential role in unravelling their contribution to the biological variations and clinical diversity observed in VWD. 1 De Wee et al., Determinants of bleeding phenotype in adult patients with moderate or severe von Willebrand disease. Thromb Haemost. 2012 Oct;108(4):683-92.

Impact of Blood Group O and Von Willebrand Factor on Bleeding Severity in Patients with Von Willebrand Disease and Bleeding Disorder of Unknown Cause

Background: In patients with bleeding, von Willebrand disease (VWD) is diagnosed at von Willebrand factor (VWF) levels of ≤50 IU/dL ( James et al. Blood Adv. 1:280-300. 2021). Nevertheless, the majority of patients with a mild to moderate bleeding disorder (MBD) is diagnosed with bleeding disorder of unknown cause (BDUC), upon exclusion of VWD, platelet function defects (PFD), and coagulation factor deficiencies (CFD). Bleeding severity in patients with VWD does not correlate well with VWF levels in type 1 VWD, suggesting other modifiers of the bleeding tendency, when patients with severe VWD are excluded. Blood group O (BG O) is associated with lower VWF levels and has been found to be overrepresented in VWD. In BDUC patients, BGO is also overrepresented and recognized as an independent risk factor for bleeding severity and recurrent bleeding ( Mehic et al. Blood Adv.20: 5157-5164. 2020; Mehic et al. JTH. 7: 1757-1768. 2023). Aim: This study aimed to comprehensively investigate the clinical phenotype of patients with VWD or BDUC from the Vienna Bleeding Biobank (VIBB) and evaluate the direct effect of ABO BG on bleeding severity beyond its effect on VWF levels. Methods: Patients with VWD or BDUC from the VIBB, a single-center cohort study (EC 603/2009), were categorized by lowest VWF, as measured by VWF:antigen (VWF:Ag) or VWF ristocetin co-factor activity (VWF:RCo), into four groups: <30 IU/dL (very low VWF), 30-50 IU/dL (low VWF), 51-80 IU/dL, and >80 IU/dL. Patients diagnosed with PFD (n=221), CFD (n=28), or other diagnoses (n=4) were excluded. To study the association of BG O with bleeding severity irrespective of VWF levels, we fitted linear regression models adjusting for age, sex, and lowest VWF. We allowed for non-linearity by modelling age and sex with restricted cubic splines. Results: A total of 637 patients, 18 (2.8%) with very low VWF, 55 (8.6%) with low VWF, 237 (37.2%) with VWF levels ranging from 51 to 80 IU/dL and 327 (51.3%) with VWF levels >80 IU/dl, were included in this analysis, as summarized in Table 1. BG O was more prevalent in patients with very low VWF levels (61%), low VWF levels (71%), and VWF levels 51-80 IU/dL (66%) than in patients with VWF levels >80 IU/dL (30%). Patients with low VWF were youngest, followed by very low VWF and those with VWF 51-80 IU/dL. Age was highest in the patient group with VWF levels >80 IU/dL at clinical presentation and might influence VWF levels and bleeding scores. With regard to bleeding severity, patients with very low VWF levels had highest median bleeding scores or number of bleeding manifestations, while the bleeding severity was similar amongst the other three categories (Table 1). VWF levels did not correlate with bleeding severity scores (Vicenza score: Spearman rho=-0.03, p=0.53; ISTH BAT: rho=-0.02, p=0.75; number of bleeding manifestations: rho=-0.02, p=0.66). In linear regression, holding age, sex, and lowest VWF levels constant, predicted mean bleeding scores and number of bleeding manifestations were higher with BG O (Vicenza score mean difference [MD], 0.64; 95% confidence interval [95%CI], 0.12 to 1.25; p=0.015; ISTH BAT MD 0.52; 95%CI, -0.25 to 1.28; p=0.18; number of bleeding manifestations MD, 0.24; 95%CI, -0.06 to 0.54; p=0.12) (Figure 1). Conclusion: Our findings demonstrate an overlap between VWD and BDUC with a similar clinical phenotype and bleeding phenotype, but increased severity in patients with VWF levels <30 IU/dL. Patients with BG O had increased bleeding scores compared to those with BG non-O. BG O appears to be an independent factor in modifying bleeding severity in both patients with VWD or BDUC across all VWF ranges.

PB0235 Phase 3 Study of the Efficacy, Pharmacokinetics, Immunogenicity and Safety of von Willebrand Factor/Factor VIII Concentrate in Patients with Severe von Willebrand Disease under 6 Years of Age

PB0235 Phase 3 Study of the Efficacy, Pharmacokinetics, Immunogenicity and Safety of von Willebrand Factor/Factor VIII Concentrate in Patients with Severe von Willebrand Disease under 6 Years of Age

Factor VIII antibody immune complexes modulate the humoral response to factor VIII in an epitope-dependent manner.

Soluble antigens complexed with immunoglobulin G (IgG) antibodies can induce robust adaptive immune responses in vitro and in animal models of disease. Factor VIII immune complexes (FVIII-ICs) have been detected in individuals with hemophilia A and severe von Willebrand disease following FVIII infusions. Yet, it is unclear if and how FVIII-ICs affect antibody development over time. In this study, we analyzed internalization of FVIII complexed with epitope-mapped FVIII-specific IgG monoclonal antibodies (MAbs) by murine bone marrow-derived dendritic cells (BMDCs) in vitro and antibody development in hemophilia A (FVIII-/-) mice injected with FVIII-IC over time. FVIII complexed with 2-116 (A1 domain MAb), 2-113 (A3 domain MAb), and I55 (C2 domain MAb) significantly increased FVIII uptake by BMDC but only FVIII/2-116 enhanced antibody titers in FVIII-/- mice compared to FVIII alone. FVIII/4A4 (A2 domain MAb) showed similar FVIII uptake by BMDC to that of isolated FVIII yet significantly increased antibody titers when injected in FVIII-/- mice. Enhanced antibody responses observed with FVIII/2-116 and FVIII/4A4 complexes in vivo were abrogated in the absence of the FVIII carrier protein von Willebrand factor. These findings suggest that a subset of FVIII-IC modulates the humoral response to FVIII in an epitope-dependent manner, which may provide insight into the antibody response observed in some patients with hemophilia A.

Challenges in the classification of von Willebrand disease with a limited test panel: An experience from an upcoming hemostasis laboratory in southern India

Objectives: The diagnosis and classification of von Willebrand disease (VWD) is an intricate process requiring multiple hemostatic tests. Cutoff values of the tests vary with the subtype. Sometimes, all the tests are not available. This study was done to analyze the clinical and coagulation profile of VWD diagnosed and broadly classified based on a simplified algorithm. Material and Methods: This was a cross-sectional study done over 6 years. After screening tests, a simplified algorithm taking cutoff for various tests based on updated guidelines using the primary panel of von Willebrand factor antigen assay (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), and Factor VIII:C was used. Multimer assay was done in a few cases. Data were compiled using summary statistics. Results: Forty patients fitted the diagnosis of VWD: Type 3 in 13 (32.5%), Type 2N (likely) in 8 (20%), Type 2 (not further categorized) in 9 (22.5%), and VWD, not further categorized in 10 (25%). The mean age was in the second or third decade with female predominance. Diagnosis of Type 3 was relatively straightforward due to markedly deranged parameters. Type 2N was provisionally diagnosed based on bleeding pattern and markedly reduced Factor VIII:C; further, subtyping of Type 2 and categorization of some cases was not possible due to non-availability of some tests. Conclusion: VWF:Ag assay, VWF:RCo, and Factor VIII:C form the cornerstone for diagnosing major VWD types. The under-representation of milder phenotypes and a greater proportion of severe VWD subtypes observed is likely due to hospital referral bias and may not represent population prevalence.

HRQoL and psychosocial aspects of burden on caregivers to children with moderate or severe von Willebrand disease.

Von Willebrand disease (VWD) is the most widespread congenital bleeding disorder. Caregivers are highly involved in its treatment, and from the time of the child's bleeding diagnosis, they face new demands such as recognition of bleeds and treatment options. The aim of this study was to assess Health related quality of life (HRQoL) in caregivers of children with moderate and severe VWD in Sweden, and to describe the impact of psychosocial aspects on the burden. A multicentre, cross-sectional study. The Short Form 36 Health Survey (SF-36) was used to assess HRQoL. Caregiver burden was measured using The HEMOphilia associated Caregiver Burden scale (HEMOCAB). Children´s clinical data were collected from the Swedish national registry for bleeding disorders. Seventy caregivers of children with moderate or severe VWD were included. Caregivers of children with moderate VWD scored significantly lower in the mental health domains on SF-36, compared to matched normative data. Psychosocial aspects that significantly impacted the caregiver burden negatively measured by HEMOCAB total score were: if the caregiver reported that VWD affected their life in general (p=.001), if the child was absent from preschool/school ≥2 day/12 months due to VWD (p=.002) or that VWD had a financial impact on the family (p=.001). This study contributes to knowledge about caregivers' HRQoL and highlights the situation of caregivers of children with moderate VWD. Furthermore, the caregiver burden was negatively affected by psychosocial aspects. Clinical follow-ups should include assessment of psychosocial aspects to identify caregivers that are at risk of high burden.

Von Willebrand Disease: Gaining a global perspective.

Recent guidelines for von Willebrand Disease (VWD) highlighted the challenges in diagnosis and management. Identifying the number of persons with VWD (PwVWD) internationally will help target support to aid diagnosis of PwVWD. To examine international registration rates of PwVWD, the influence of income status, geographical region and the age and sex profile. Cumulatively, these data will be used to inform future strategy from the World Federation of Haemophilia (WFH) to address unmet clinical and research needs. Data from the 2018/2019 WFH Annual Global Survey (AGS) were analysed, providing a global perspective on VWD registration. Registration rates are lowest in South Asia (0.6/million population) and highest in Europe/Central Asia (50.9/million population, 0.005%), but below the expected prevalence rate (0.1%). National economic status impacted VWD registration rates, reflecting variation in access to optimal healthcare infrastructure. Females represented the majority of PwVWD globally, however, in low-income countries (LIC) males predominated. Age profile varied, with markedly higher rates of paediatric registrations in North America, Middle East and North Africa and South Asia. Rates of type 3 VWD registrations were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings. Significant variation in registration rates of PwVWD exist internationally and is influenced by income status and the presence of HTC networks. Improved understanding of registration rates will enable targeting of advocacy to improve awareness, diagnosis and support for PwVWD internationally. Registration rates of People with Von Willebrand Disease (PwVWD) vary internationally and are influenced by national income status Although females represent the majority of PwVWD globally, in low income countries (LIC) males predominated, possibly related to stigma surrounding gynaecological bleeding. Rates of type 3 VWD registration were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings.

Efficacy of platelet-inspired hemostatic nanoparticles on bleeding in von Willebrand disease murine models

AbstractThe lack of innovation in von Willebrand disease (VWD) originates from many factors including the complexity and heterogeneity of the disease but also from a lack of recognition of the impact of the bleeding symptoms experienced by patients with VWD. Recently, a few research initiatives aiming to move past replacement therapies using plasma-derived or recombinant von Willebrand factor (VWF) concentrates have started to emerge. Here, we report an original approach using synthetic platelet (SP) nanoparticles for the treatment of VWD type 2B (VWD-2B) and severe VWD (type 3 VWD). SP are liposomal nanoparticles decorated with peptides enabling them to concomitantly bind to collagen, VWF, and activated platelets. In vitro, using various microfluidic assays, we show the efficacy of SPs to improve thrombus formation in VWF-deficient condition (with human platelets) or using blood from mice with VWD-2B and deficient VWF (VWF-KO, ie, type 3 VWD). In vivo, using a tail-clip assay, SP treatment reduced blood loss by 35% in mice with VWD-2B and 68% in mice with VWF-KO. Additional studies using nanoparticles decorated with various combinations of peptides demonstrated that the collagen-binding peptide, although not sufficient by itself, was crucial for SP efficacy in VWD-2B; whereas all 3 peptides appeared necessary for mice with VWF-KO. Clot imaging by immunofluorescence and scanning electron microscopy revealed that SP treatment of mice with VWF-KO led to a strong clot, similar to those obtained in wild-type mice. Altogether, our results show that SP could represent an attractive therapeutic alternative for VWD, especially considering their long half-life and stability.

Phenotypic and genotypic (exon 28) characterization of patients diagnosed with von Willebrand disease type 1 in Eastern Saudi Arabia.

Von Willebrand factor (VWF) is a plasma glycoprotein that plays a key role in hemostasis. Mutations in this protein can result in von Willebrand disease (VWD), the most common form of bleeding disorder in humans. Patients with type 1 VWD have a quantitative plasmatic deficiency of normal structural and functional VWF. Our study aimed to investigate the phenotypic and genotypic characteristics of VWD type 1 patients in eastern Saudi Arabia, focusing on exon 28. We included patients previously diagnosed with WWD type 1 at the King Fahad teaching hospital in Al Khobar and their family members. The correlations between various phenotypic data and genotypic (exon 28) were analyzed using statistical software (SPSS) version 21. While these variants were generally considered benign with minor clinical effects, our analysis did identify two pathogenic variants that could lead to severe VWD symptoms. Specifically, we found these two pathogenic variants in three VWD patients from Saudi Arabia, providing essential insights into pathogenic VWD mutations in this population. Our study, therefore, sheds light on the prevalence of VWF variants in the eastern province of the Kingdom and highlights the need for continued research into the genetic causes of VWD in this region.

Advances in the therapy for von Willebrand disease

Von Willebrand disease (VWD) is caused by quantitative or qualitative deficiencies in the von Willebrand factor (VWF). VWF concentrate replacement therapy is required in certain situations, such as severe VWD subtype or critical bleeding, even in mild VWD subtypes. A single plasma-derived factor VIII/VWF concentrate has been available for decades in Japan. However, it has a theoretical risk of infectious disease transmission, allergic reactions, and thrombosis. A recombinant VWF (vonicog alfa) was approved by the Japanese Pharmaceuticals and Medical Devices Agency in 2020. Vonicog alfa is the only VWF product that contains ultralarge multimer, suggesting both effective bleeding control and excessive platelet plug formation. The efficacy and safety of vonicog alfa have been confirmed by three phases of clinical studies for on-demand usage, elective surgery, and prophylaxis. We also have a successful experience with vonicog alfa with minimal adverse events in two cases (hemostatic treatment in a patient with recurrent epistaxis and prophylaxis for delivery in a pregnant woman).

Quality of Life in Patients with Clinically Severe Von Willebrand Disease: Interim Analysis of Athn 9: A Natural History Study for People with Severe Von Willebrand Disease (VWD)

Background: Von Willebrand Disease (VWD) is the most common inherited bleeding disorder, which results from either a quantitative (Type 1 or 3) or qualitative (Type 2) defect in von Willebrand Factor (VWF). Prior studies, largely focused on individuals with mild VWD and bleeding symptoms, have shown significant reductions in quality of life in patients with Von Willebrand disease. Because of the rarity less is known about individuals with severe forms of VWD or those with a severe bleeding phenotype. Aim: To report quality of life measures in participants with clinically severe VWD in the United States (US). Study Design and Methods: ATHN 9 Severe VWD Natural History Study is sponsored by the American Thrombosis and Hemostasis Network (ATHN) and is being conducted at 25 ATHN-affiliated sites across the US. ATHN 9 is an observational study focused on persons with clinically severe VWD treated with VWF factor on demand or for prophylaxis. Participants are identified by site investigators with a projected goal to enroll 130 individuals. Patients with severe VWD defined as type 3 VWD, or a VWF:RCo, VWF:GPIbM or VWF:Ag ≤ 30%, or persons with "clinically severe VWD" defined by VWF:RCo, VWF:GPIbM or VWF:Ag ≤ 40% and requiring recurrent use of factor concentrates, and prior enrollment in the ATHNdataset national surveillance data collection project are included. Participants with platelet-type or acquired VWD are excluded. Quality of life was assessed using PROMIS measures (PROMIS 25, PROMIS 25 Proxy, PROMIS 29) and the VWIQ at enrollment, annually, and at study exit. PROMIS-29 assesses seven different quality of life domains (physical function, anxiety, depression, fatigue, sleep disturbance, ability to participate in social roles, and pain interference) and has been validated in adult populations. PROMIS measures in the general US population have a mean of 50 and standard deviation of 10. PROMIS-25 is a pediatric questionnaire assessing the same domains (except for sleep disturbance) and an accompanying proxy form for caregivers of participants <8 years of age. Baseline enrollment results are reported here. Results: Enrollment (baseline) PROMIS-29 forms were completed by 43 participants. At baseline, mean physical function was lower than the general population at 45.7 (p=0.005), and fatigue and pain interference were greater than the general population at 53.2 and 53 respectively (p=0.036 and 0.049 respectively). Individuals on continuous VWF factor prophylaxis (n=18) had significantly decreased physical function (p<0.01), and decreased ability to participate in social roles (p<0.01) than individuals on episodic treatment (n=19). Enrollment PROMIS-25 forms were completed for 26 participants, while PROMIS-25 proxy forms were completed for 19 participants. Mean enrollment scores for PROMIS-25 depression symptoms was lower than the general population at 44.4 (p=0.0004) and peer relationships were better than the general population at 54 (p=0.042). Mean enrollment scores for PROMIS-25 Proxy were lower than the general population for depression, fatigue, and pain interference at 41, 42.9, and 45.4 respectively (p<0.0001, p=0.002, and p=0.045 respectively). In contrast to the adult participants, no statistically significant differences were seen between pediatric participants on VWF factor prophylaxis versus episodic treatment. Discussion: Pediatric participants with clinically severe VWD reported less depression and better peer relationships than the general population, and parents of pediatric participants with VWD reported less depression, fatigue, and pain interference in their children compared to the general population. Patient-reported outcomes in adult participants were less encouraging with worse physical function, and more fatigue and pain interference compared to the general population. Adult participants on VWF factor prophylaxis had decreased physical function, and decreased ability to participate in social roles compared to adults treated episodically, perhaps secondary to disease severity and accumulation of bleed-related morbidity. No statistically significant differences were seen in quality of life outcomes between pediatric patients on VWF factor prophylaxis and those on episodic treatment. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Structure and Function of Recombinant versus Plasma-Derived von Willebrand Factor and Impact on Multimer Pharmacokinetics in von Willebrand Disease.

Recombinant von Willebrand factor (rVWF, vonicog alfa) is a purified VWF concentrate produced from Chinese hamster ovary cells. rVWF is not exposed to the VWF-cleaving protease ADAMTS13 and so is not subject to proteolytic degradation of large (L) and ultra-large (UL) VWF multimers by that enzyme. To compare the structure and function of rVWF with the human plasma-derived VWF [pdVWF] concentrates Haemate P®/Humate-P®, Voncento®, Wilate®/Eqwilate®, and Wilfactin®/Willfact®; to investigate the relationship between VWF multimeric pattern and VWF:ristocetin cofactor (VWF:RCo) activity through population pharmacokinetic (PK) modeling in patients with severe von Willebrand disease (VWD) treated with rVWF. Analyses included VWF:RCo activity, VWF:collagen-binding activity, VWF:platelet glycoprotein Ib receptor binding, factor VIII (FVIII) binding capacity, and VWF-mediated platelet adhesion under flow conditions. VWF multimeric structure was determined by agarose gel electrophoresis. Population PK models describing the activity-time profile of small, medium, and L/UL multimers following intravenous administration of rVWF in patients with severe VWD were developed. Findings demonstrate that rVWF contains a non-degraded VWF multimer pattern including the UL multimers not present in pdVWF concentrates. rVWF displayed higher specific platelet-binding activity, and faster mediation of platelet adhesion to collagen under shear stress versus pdVWF concentrates. rVWF also demonstrated higher FVIII binding capacity than Haemate P®, Voncento® and Wilate®. Modeling provided evidence that VWF:RCo activity in patients with severe VWD treated with rVWF is associated with L/UL VWF multimers in the circulation. Findings suggest that the L and UL multimers preserved in rVWF contribute to high biological activity and might be important for providing hemostatic efficacy.

Clinical, economic, and health-related quality of life burden associated with von Willebrand disease in adults and children: Systematic and targeted literature reviews.

Debilitating clinical complications in von Willebrand disease (VWD) can affect health-related quality of life (HRQoL), increase healthcare costs and cause long-lasting consequences. However, the magnitude of these burdens needs to be more fully explored. To estimate the prevalence and burden of clinical complications, the impact on HRQoL and the economic burden associated with VWD. Embase® , MEDLINE® , the Cochrane Library and conference proceedings were searched for studies on VWD evaluating clinical complications, HRQoL and cost and resource use. Among 16 studies assessing clinical complications in VWD, the most prevalent bleeding symptoms were menorrhagia (2%-95% [n =7 studies]), epistaxis (12%-80% [n =6]) and easy bruising (46%-65% [n =2]). Among 17 studies evaluating HRQoL, the most common assessment scales were the generic SF-36 (n =8 studies) and the EQ-5D (n =2). Bleeding symptoms were associated with reduced QoL in six of seven studies, and of six studies evaluating treatment impact, four reported improvements in one or more HRQoL components. Among 25 studies on cost and resource use, key observations included higher post-surgery healthcare costs in VWD versus non-VWD patients (n =1 study) and higher costs and resource use in VWD patients with bleeding complications versus those without (n =1). Although limited, available evidence suggests that VWD patients experience a high burden of clinical complications, reduced QoL and high healthcare costs. Haemarthrosis is more common in severe VWD than is often assumed, and bleeds (including haemarthrosis) can reduce QoL. Research efforts to improve QoL and other outcomes should be prioritized.

Recombinant von Willebrand factor prophylaxis in patients with severe von Willebrand disease: phase 3 study results

AbstractInternational guidelines conditionally recommend long-term prophylaxis in patients with von Willebrand disease (VWD) and severe and frequent bleeding. As recombinant von Willebrand factor (rVWF; vonicog alfa) may reduce the frequency of treated spontaneous bleeding events (BEs), we investigated the efficacy and safety of rVWF prophylaxis in adults with severe VWD. Patients with BEs requiring VWF therapy in the past year (on-demand VWF therapy [prior on-demand group] or plasma-derived VWF prophylaxis [pdVWF; switch group]) were enrolled in a prospective, open-label, nonrandomized, phase 3 study. The planned duration of rVWF prophylaxis was 12 months; starting rVWF dose was 50 ± 10 VWF: ristocetin cofactor (VWF:RCo) IU/kg twice weekly (prior on-demand group) or based on prior pdVWF weekly dose/dosing frequency (switch group). The primary endpoint was annualized bleeding rate (ABR) of treated spontaneous BEs (sABR) during rVWF prophylaxis. Over the 12-month study period, treated sABR decreased by 91.5% on-study vs historical sABR in 13 patients in the prior on-demand group, and by 45.0% in 10 patients in the switch group (model-based analysis ratio, 0.085; 95% confidence interval [CI], 0.021-0.346 and 0.550; 95% CI, 0.086-3.523, respectively). No treated spontaneous BEs were recorded in 84.6% (11/13) and 70.0% (7/10) of patients, respectively. The safety profile of rVWF was consistent with the previously established profile, with no new adverse drug reactions identified. Findings suggest that rVWF prophylaxis can reduce treated spontaneous BEs in patients previously receiving on-demand VWF therapy and maintains at least the same level of hemostatic control in patients who switch from prophylaxis with pdVWF to rVWF, with a favorable safety profile. This trial was registered at www.clinicaltrials.gov (#NCT02973087) and www.clinicaltrialsregister.eu (#EudraCT 2016-001478-14).

Efficacy and safety of von Willebrand factor concentrate almost devoid of factor VIII (Wilfactin®) in paediatric patients under 6 years of age with severe von Willebrand disease.

Plasma-derived von Willebrand factor (VWF) (Wilfactin®, LFB, France) was developed for prophylaxis and treatment of haemorrhages in both adults and adolescents with von Willebrand disease (VWD). Replacement therapy in paediatric patients is a key element of the clinical trial programme. Patients aged <6 years with severe VWD were enrolled in a multinational, open-label study to evaluate the in vivo recovery for Wilfactin®, and its efficacy in preventing and treating bleeding episodes and during surgery. Overall haemostatic efficacy based on a 4-point scale was assessed by investigators. The treatment period ≥18 months investigated the long-term safety. Nine patients, including 7 with type 3 VWD were exposed to treatment with Wilfactin® for up to 4.2 years. Recovery of VWF in 7 patients (n=5 type 3, n=1 type 2, n=1 type 1) was 1.8±0.4 IU/dL per IU/kg. Of the 62 bleeds, 89% were controlled with one (73%) or two (16%) infusions of Wilfactin®. The median dose per infusion was 54 IU/kg. A factor VIII dose was co-administered in 1.6% of bleeds. "Excellent"/"Good" haemostatic efficacy was achieved in 90.3% of episodes. Six patients underwent 11 minor surgical interventions. Treatment duration was 1 day (range: 1-6 days) with a dose administered 30-60 minutes before procedure of 56 IU/kg (range: 41-106 IU/kg). Haemostasis was rated as "Excellent" in all surgeries. During 4-year prophylactic treatment in one patient, breakthrough bleeds were reported in 2.2% of infusions. No VWF inhibitors, thromboembolic events or allergic/anaphylactic-type reactions were observed following a total exposure of 770 days. The results show that Wilfactin® provides a safe and effective treatment in patients <6 years of age with severe VWD.

Efficacy of emicizumab in von Willebrand disease (VWD) patients with and without alloantibodies to von Willebrand factor (VWF): Report of two cases and review of literature

von Willebrand disease (VWD) is the common bleeding disorder with a clinically relevant bleeding prevalence of 1:10,000. von Willebrand disease patients lack both von Willebrand factor (VWF) and factor VIII (FVIII), which are critical for normal haemostasis. The conventional treatment for VWD includes desmopressin and replacement therapy with plasma derived FVIII with VWF concentrates or recombinant VWF. Development of alloantibodies is a rare occurrence, there is a paucity in the literature of treatment modalities in these patients. Not many reports are available in literature on the efficacy of emicizumab in VWD patients with or without alloantibodies to VWF. To do systematic review of literature on emicizumab in VWD and report our experience of emicizumab in two patients of VWD METHODS: We used electronic search engines till May 2021 in 'Google scholar' and 'PubMed', to collect the case reports or case series on use of emicizumab for management of VWD. Two of our severe VWD patients were successfully treated with emicizumab. A systematic review was performed and the results discussed. The electronic search revealed six case reports using emicizumab for treatment of VWD. Two were in vitro studies and four in patients with VWD type 3 disease. In vitro studies and in VWD patients on emicizumab, showed improvement in thrombin generation and fibrin formation. Among four patients, three had alloantibodies to VWD and one was negative. All these patients were treated with emicizumab for 6-12m. After starting emicizumab, none of them had spontaneous bleeding requiring treatment. During treatment with emicizumab, one patient had trauma-associated soft tissue hematoma, which was treated with rFVIIa and another patient had bleeding following dental exfoliation treated with Humate P. We treated two of our VWD patients one with and one without inhibitors with emicizumab after failure of other therapies. Both the patients showed marked improvement and continued to remain well and free of bleeding episodes. None of the patients had any thrombosis or thrombotic microangiopathy (TMA) during treatment with emicizumab. In conclusion, this review supports the safety and efficacy of emicizumab in type 3 VWD patients with or without alloantibodies. Further large studies are required to confirm the safety and efficacy of emicizumab in VWD.