How I manage severe von Willebrand disease

Factor VIII stimulants and other novel therapies for the treatment of von Willebrand disease: what's new on the horizon?

INTRODUCTION

Von Willebrand disease (VWD) is the most common inherited bleeding disorder, affecting about 0.6% to 1.3% of the population, and is characterized primarily by mucocutaneous bleeding secondary to defective platelet adhesion and aggregation. Current therapeutic options for those with severe disease are limited and require frequent intravenous infusions.

AREAS COVERED

This review discusses the current and recently completed clinical trials involving pathways to FVIII augmentation for the treatment of VWD. Clinical trials registered on clinicaltrials.gov and published data via PubMed searches through June 2024 were included.

EXPERT OPINION

Available treatment options to those with VWD are limited in part due to limited clinical trials, the complexity of VWD types, and the pharmacokinetics of current treatment options. The development of therapeutic options that reduce treatment burden is necessary to improve quality of life and reduce bleeding complications and in recent years there has been an increased interest from industry to apply novel therapeutics for VWD. The FVIII mimetic, emicizumab, has demonstrated early success in patients with severe VWD and is a promising treatment option for those who require prophylaxis. Furthermore, products like efanesoctocog alfa (Altuviiio®) and BT200 have achieved enhanced VWF/FVIII half-life extension could expand the current treatment landscape while concurrently minimizing treatment burden.

Emicizumab in Type 3 von Willebrand Disease: Report of a Case with an Alloantibody and Literature Review

Type 3 von Willebrand disease (VWD), the most severe form of VWD, is an inherited recessive bleeding disorder caused by the complete deficiency of von Willebrand factor (VWF). The reported prevalence is 1 per million but varies worldwide according to the frequency of consanguineous marriages. The clinical phenotype is characterized not only by mucocutaneous bleedings, but also by hemarthroses and muscle hematoma, as in patients with moderate hemophilia. Long-term prophylaxis with factor (F)VIII/VWF concentrates is recommended in patients with a history of severe and frequent bleeds. A rare complication of replacement therapy is the development of alloantibodies against VWF, with the consequences of an ineffective therapy and risk of anaphylactic reactions upon treatment. Emicizumab is the first bispecific monoclonal antibody that mimics FVIII coagulant activity and is approved for prophylaxis of bleeding in patients with inherited hemophilia A with or without inhibitors and recently also for acquired hemophilia. In this manuscript we report and discuss available data in the literature on the use of emicizumab in type 3 VWD and describe the case of a female patient with type 3 VWD with a history of alloantibodies against VWF and posttransfusion anaphylaxis, recently and successfully put on off-label prophylaxis with emicizumab.

Early Postoperative Changes in Von Willebrand Factor Activity Are Associated With Future Bleeding and Stroke in HeartMate 3 Patients

Hemocompatibility-related adverse events (HRAEs), particularly gastrointestinal bleeding, remain a frequent complication after left ventricular assist device (LVAD) implantation. The current study sought to describe and analyze whether early (<60 days) postoperative von Willebrand factor (VWF) activity assays predict the risk of gastrointestinal bleeding and stroke. A prospective single-center study including 74 HeartMate 3 device recipients between 2016 and 2023 was undertaken. The postoperative trajectory of the VWF profile was analyzed using linear mixed-effect models and Cox models were used to quantify associations between an early postoperative dip (≤0.7) in VWF activity assay measurements and late outcomes. Preoperatively, the mean VWF:Activity (Act)/Antigen (Ag) and VWF:Collagen Binding (CB)/Ag ratios were 0.94 (95% confidence interval [CI] = 0.81-1.02) and 0.95 (95% CI = 0.80-1.03), respectively, decreasing to 0.66 (95% CI = 0.57-0.73) and 0.67 (95% CI = 0.58-0.74) within 40 days (p < 0.05). In patients with VWF:CB/Ag and VWF:Act/Ag ratios ≤0.7 significantly more gastrointestinal bleeding (hazard ratio [HR]: 2.53; 95% CI = 1.1-5.8, and HR: 3.7; 95% CI = 1.5-9.2, respectively) and hemorrhagic stroke events (HR: 3.5; 95% CI = 1.6-7.6 and HR: 4.9; 95% CI = 2.1-11.7, respectively) were observed throughout the entire late (>60 days) postoperative period. In patients with VWF:Act/Ag ratio ≤0.7 less ischemic stroke events were observed (HR: 0.11; 95% CI = 0.01-0.85). In conclusion, VWF:Act/Ag and VWF:CB/Ag ratios ≤0.7 in the early postoperative phase can be used as biomarkers to predict HRAEs during long-term LVAD support.

Hemophilia A: Emicizumab monitoring and impact on coagulation testing

Hemophilia A is an X-linked recessive bleeding disorder characterized by absent or ineffective coagulation factor VIII, a condition that could result in a severe and potentially life-threatening bleed. Although the current standard of care involves prophylactic replacement therapy of factor VIII, the development of neutralizing anti-factor VIII alloantibody inhibitors often complicates such therapeutic treatment. Emicizumab (Hemlibra®), a novel recombinant therapeutic agent for patients with hemophilia A, is a humanized asymmetric bispecific IgG4 monoclonal antibody designed to mimic activated factor VIII by bridging factor IXa and factor X thus effecting hemostasis. Importantly, this drug eliminates the need for factor VIII and complications associated with inhibitor generation. Emicizumab has been approved for use in several countries including the United States and Japan for prophylaxis of bleeding episodes in hemophilia A with and without FVIII inhibitors. Therapy is also approved in the European Union for routine prophylaxis of bleeds in hemophilia A with inhibitors or severe hemophilia A without inhibitors. Unfortunately, emicizumab therapy presents unique challenges for routine and specialty coagulation tests currently used to monitor hemophilia A. In this review, hemophilia A is presented, the biochemistry of factor VIII is discussed, and the impact of the therapeutic agent emicizumab is highlighted.

The diagnosis, natural history, and management of von Willebrand disease in women in the age of guidelines

INTRODUCTION

Women and girls with bleeding disorders face multiple bleeding challenges throughout their life. The most significant morbidity and mortality are due to heavy menstrual bleeding and postpartum hemorrhage in their reproductive years. The ASH/ISTH/NHF/WFH 2021 guidelines on diagnosing and managing von Willebrand disease (VWD) provide several new updates.

AREAS COVERED

Women with VWD have a higher prevalence of heavy menstrual bleeding. The subpopulation of adolescents is particularly vulnerable, as the diagnosis is often delayed with increased comorbidity of iron deficiency anemia and associated symptoms. A detailed review is done on the prevalence of bleeding-related complications, especially heavy menstrual bleeding (HMB) and post-partum hemorrhage (PPH). The management strategies are also reviewed in detail, with a specific focus on the target factor levels and the use of antifibrinolytics.

EXPERT OPINION

The 2021 ASH/ISTH/NHF/WFH diagnostic and management recommendations are reviewed with a specific focus on hormonal methods of HMB management and antifibrinolytics in this situation. The reviewed topics include neuraxial anesthesia, factor cutoff, and tranexamic acid use in the postpartum period.

Type 1 von Willebrand Disease in a Pediatric Patient Caused by a Novel Heterozygous Deletion of Exons 1 to 6 of the von Willebrand Factor Gene: A Case Report

A 6-year-old boy was referred to a hematologist due to excessive mucocutaneous bleeding. Diagnostic assessment for von Willebrand disease (VWD) was indicated and included both coagulation and genetic testing. Laboratory testing revealed proportionally decreased von Willebrand factor (VWF) glycoprotein Ib-binding activity (23.6%) compared to VWF antigen (24.7%), similarly decreased VWF collagen-binding activity (24.2%), and normally distributed VWF multimers, with decreased intensity of all fractions. Diagnosis of type 1 VWD was established. Genetic analysis by means of next-generation sequencing (NGS) of VWF and coagulation factor VIII genes did not identify any causative mutations. Additionally, multiplex ligation-dependent probe amplification (MLPA) of VWF gene exons revealed a heterozygous deletion of exons 1 to 6, which is reported in type 1 VWD for the first time. Application of MLPA was crucial for revealing the genetic basis of type 1 VWD in this case, which would have remained undetected if only NGS was used.

The Vascular Endothelium and Coagulation: Homeostasis, Disease, and Treatment, with a Focus on the Von Willebrand Factor and Factors VIII and V

The vascular endothelium has several important functions, including hemostasis. The homeostasis of hemostasis is based on a fine balance between procoagulant and anticoagulant proteins and between fibrinolytic and antifibrinolytic ones. Coagulopathies are characterized by a mutation-induced alteration of the function of certain coagulation factors or by a disturbed balance between the mechanisms responsible for regulating coagulation. Homeostatic therapies consist in replacement and nonreplacement treatments or in the administration of antifibrinolytic agents. Rebalancing products reestablish hemostasis by inhibiting natural anticoagulant pathways. These agents include monoclonal antibodies, such as concizumab and marstacimab, which target the tissue factor pathway inhibitor; interfering RNA therapies, such as fitusiran, which targets antithrombin III; and protease inhibitors, such as serpinPC, which targets active protein C. In cases of thrombophilia (deficiency of protein C, protein S, or factor V Leiden), treatment may consist in direct oral anticoagulants, replacement therapy (plasma or recombinant ADAMTS13) in cases of a congenital deficiency of ADAMTS13, or immunomodulators (prednisone) if the thrombophilia is autoimmune. Monoclonal-antibody-based anti-vWF immunotherapy (caplacizumab) is used in the context of severe thrombophilia, regardless of the cause of the disorder. In cases of disseminated intravascular coagulation, the treatment of choice consists in administration of antifibrinolytics, all-trans-retinoic acid, and recombinant soluble human thrombomodulin.

Desmopressin response depends on the presence and type of genetic variants in patients with type 1 and type 2 von Willebrand disease

All type 1 VWD patients without a VWF gene variant have a complete response to desmopressin.

In type 1 and type 2 VWD patients with a VWF gene variant, desmopressin response highly depends on the causative VWF gene variant.

Patients with type 1 and type 2 von Willebrand disease (VWD) can be treated with desmopressin. Although a previous study has shown that the location of the causative VWF gene variant is associated with desmopressin response in type 1 VWD, the association between variants in the VWF gene and desmopressin response is not yet fully understood. Our primary aim was to compare desmopressin response in type 1 VWD patients with and without a VWF gene variant. Secondly, we investigated whether desmopressin response depends on specific VWF gene variants in type 1 and type 2 VWD. We included 250 patients from the Willebrand in the Netherlands study: 72 type 1 without a VWF gene variant, 108 type 1 with a variant, 45 type 2A, 16 type 2M, and 9 type 2N patients. VWF gene was analyzed with ion semiconductor sequencing and Multiplex Ligation-dependent Probe Amplification. Complete response to desmopressin was observed in all type 1 VWD patients without a variant, 64.3% of type 1 patients with a variant, and 31.3% of type 2 patients (P < .001). Despite a large interindividual variability in desmopressin response, patients with the same variant had comparable desmopressin responses. For instance, in 6 type 1 patients with exon 4 to 5 deletion, mean VWF activity at 1 hour after desmopressin was 0.81 IU/mL, with a coefficient of variation of 22.9%. In conclusion, all type 1 VWD patients without a VWF gene variant respond to desmopressin. In type 1 and type 2 VWD patients with a VWF variant, desmopressin response highly depends on the VWF gene variants.

Von Willebrand disease type 2M: Correlation between genotype and phenotype

BACKGROUND

An appropriate clinical diagnosis of von Willebrand disease (VWD) can be challenging because of a variable bleeding pattern and laboratory phenotype. Genotyping is a powerful diagnostic tool and may have an essential role in the diagnostic field of VWD.

OBJECTIVES

To unravel the clinical and laboratory heterogeneity of genetically confirmed VWD type 2M patients and to investigate their relationship.

METHODS

Patients with a confirmed VWD type 2M genetic variant in the A1 or A3 domain of von Willebrand factor (VWF) and normal or only slightly aberrant VWF multimers were selected from all subjects genotyped at the Radboud university medical center because of a high suspicion of VWD. Bleeding scores and laboratory results were analyzed.

RESULTS

Fifty patients had a clinically relevant genetic variant in the A1 domain. Median bleeding score was 5. Compared with the nationwide Willebrand in the Netherlands study type 2 cohort, bleeding after surgery or delivery was reported more frequently and mucocutaneous bleedings less frequently. Median VWF activity/VWF antigen (VWF:Act/VWF:Ag) ratio was 0.32, whereas VWF collagen binding activity/VWF antigen (VWF:CB/VWF:Ag) ratio was 0.80. Variants in the A3 domain were only found in two patients with low to normal VWF:Act/VWF:Ag ratios (0.45, 1.03) and low VWF:CB/VWF:Ag ratios (0.45, 0.63).

CONCLUSION

Genetically confirmed VWD type 2M patients have a relatively mild clinical phenotype, except for bleeding after surgery and delivery. Laboratory phenotype is variable and depends on the underlying genetic variant. Addition of genotyping to the current phenotypic characterization may improve diagnosis and classification of VWD.

Platelets' Role in Dentistry: From Oral Pathology to Regenerative Potential

Platelets are a cellular subgroup of elements circulating in the bloodstream, responsible for the innate immunity and repairing processes. The diseases affecting this cellular population, depending on the degree, can vary from mild to severe conditions, which have to be taken into consideration in cases of minor dental procedures. Their secretion of growth factors made them useful in the regenerative intervention. The aim of this review is to examine the platelets from biological, examining the biogenesis of the platelets and the biological role in the inflammatory and reparative processes and clinical point of view, through the platelets' pathology and their use as platelets concentrates in dental regenerative surgery.

Gastrointestinal Bleeding in Congenital Bleeding Disorders

Gastrointestinal bleeding (GIB) is serious, intractable, and potentially life-threatening condition. There is considerable heterogeneity in GIB phenotypes among congenital bleeding disorders (CBDs), making GIB difficult to manage. Although GIB is rarely encountered in CBDs, its severity in some patients makes the need for a comprehensive and precise assessment of underlying factors and management approaches imperative. Initial evaluation of GIB begins with assessment of hematological status; GIB should be ruled out in patients with chronic anemia, and in presentations that include hematemesis, hematochezia, or melena. High-risk patients with recurrent GIB require urgent interventions such as replacement therapy for treatment of coagulation factor deficiency (CFD). However, the best management strategy for CFD-related bleeding remains controversial. While several investigations have identified CBDs as potential risk factors for GIB, research has focused on assessing the risks for individual factor deficiencies and other CBDs. This review highlights recent findings on the prevalence, management strategies, and alternative therapies of GIB related to CFDs, and platelet disorders.

Hemostatic profile detailing in apparent VWD cases: A cross sectional study

The von willebrand disease (vWD) accounts to be one of the most common hereditary bleeding ailment that amounts its incidence to almost 1.5% of normal population. It is mostly associated with a defect in primary hemostasis as well as secondary defect in coagulation factor VIII as diagnosis of vwd happened to be challenging with earlier diagnostic criteria's. Testing Vwd in menorrhagia patients was not at ease. A cross-sectional study was conducted in female patients who have visited obstetrics and gynecology clinic at King Saud University Medical City (KSUMC), Riyadh, Saudi Arabia. The inclusion criteria consist of adult female patients between 16 and 45 years old with menorrhagia. A sample of 45 patients were screened and selected for the above-mentioned study. The SPSS Statistical analysis package was performed to analyze the data's. The fisher's exact test was conducted to compare the demographic variables. The independent samples t-test was conducted to compare the means of subjects. The P value of ≤0.05 considered as statistically significant. The cases manifested with a history of bleeding during periods stretching from 7 to 90 days. The vWD was reported in 6.6 % (n = 3) women out of the total 45 patients. The vWF: Ac mean ± SD (51.4 ± 6.3) and vWF: Ag Mean ± SD (93 ± 67) were significantly lesser in vWD patients with that of non-vWD (98.7 ± 22.6) vs (116 ± 42.4) (p = 0.027) (p = 0.032) respectively. WBC, ESR, MCV, MCH, Hemoglobin, PLT count, INR, PT, APTT and FVIII showed no significant difference among the groups (p > 0.05).

Quantitative 3D microscopy highlights altered von Willebrand factor α-granule storage in patients with von Willebrand disease with distinct pathogenic mechanisms

BACKGROUND

Platelets play a key role in hemostasis through plug formation and secretion of their granule contents at sites of endothelial injury. Defects in von Willebrand factor (VWF), a platelet α-granule protein, are implicated in von Willebrand disease (VWD), and may lead to defective platelet adhesion and/or aggregation. Studying VWF quantity and subcellular localization may help us better understand the pathophysiology of VWD.

OBJECTIVE

Quantitative analysis of the platelet α-granule compartment and VWF storage in healthy individuals and VWD patients.

PATIENTS/METHODS

Structured illumination microscopy (SIM) was used to study VWF content and organization in platelets of healthy individuals and patients with VWD in combination with established techniques.

RESULTS

SIM capably quantified clear morphological and granular changes in platelets stimulated with proteinase-activated receptor 1 (PAR-1) activating peptide and revealed a large intra- and interdonor variability in VWF-positive object numbers within healthy resting platelets, similar to variation in secreted protein acidic and rich in cysteine (SPARC). We subsequently characterized VWD platelets to identify changes in the α-granule compartment of patients with different VWF defects, and were able to stratify two patients with type 3 VWD rising from different pathological mechanisms. We further analyzed VWF storage in α-granules of a patient with homozygous p.C1190R using electron microscopy and found discrepant VWF levels and different degrees of multimerization in platelets of patients with heterozygous p.C1190 in comparison to VWF in plasma.

CONCLUSIONS

Our findings highlight the utility of quantitative imaging approaches in assessing platelet granule content, which may help to better understand VWF storage in α-granules and to gain new insights in the etiology of VWD.

Endothelial Dysfunction, Atherosclerosis, and Increase of von Willebrand Factor and Factor VIII: A Randomized Controlled Trial in Swine

It is well known that high von Willebrand factor (VWF) and factor VIII (FVIII) levels are associated with an increased risk of cardiovascular disease. It is still debated whether VWF and FVIII are biomarkers of endothelial dysfunction and atherosclerosis or whether they have a direct causative role. Therefore, we aimed to unravel the pathophysiological pathways of increased VWF and FVIII levels associated with cardiovascular risk factors. First, we performed a randomized controlled trial in 34 Göttingen miniswine. Diabetes mellitus (DM) was induced with streptozotocin and hypercholesterolemia (HC) via a high-fat diet in 18 swine (DM + HC), while 16 healthy swine served as controls. After 5 months of follow-up, FVIII activity (FVIII:C) was significantly higher in DM + HC swine (5.85 IU/mL [5.00-6.81]) compared with controls (4.57 [3.76-5.40], p = 0.010), whereas VWF antigen (VWF:Ag) was similar (respectively 0.34 IU/mL [0.28-0.39] vs. 0.34 [0.31-0.38], p = 0.644). DM + HC swine had no endothelial dysfunction or atherosclerosis during this short-term follow-up. Subsequently, we performed a long-term (15 months) longitudinal cohort study in 10 Landrace-Yorkshire swine, in five of which HC and in five combined DM + HC were induced. VWF:Ag was higher at 15 months compared with 9 months in HC (0.37 [0.32-0.42] vs. 0.27 [0.23-0.40], p = 0.042) and DM + HC (0.33 [0.32-0.37] vs. 0.25 [0.24-0.33], p = 0.042). Both long-term groups had endothelial dysfunction compared with controls and atherosclerosis after 15 months. In conclusion, short-term hyperglycemia and dyslipidemia increase FVIII, independent of VWF. Long-term DM and HC increase VWF via endothelial dysfunction and atherosclerosis. Therefore, VWF seems to be a biomarker for advanced cardiovascular disease.

von Willebrand disease: what does the future hold?

von Willebrand disease (VWD) is characterized by its heterogeneous clinical manifestation, which complicates its diagnosis and management. The clinical management of VWD has remained essentially unchanged over the last 30 years or so, using von Willebrand factor (VWF) concentrates, desmopressin, and anti-fibrinolytic agents as main tools to control bleeding. This is in contrast to hemophilia A, for which a continuous innovative path has led to novel treatment modalities. Despite current VWD management being considered effective, quality-of-life studies consistently reveal a higher than anticipated burden of VWD on patients, which is particularly true for women. Apparently, despite our perceived notion of current therapeutic efficiency, there is space for innovation with the goal of reaching superior efficacy. Developing innovative treatments for VWD is complex, especially given the heterogeneity of the disease and the multifunctional nature of VWF. In this perspective article, we describe several potential strategies that could provide the basis for future VWD treatments. These include genetic approaches, such as gene therapy using dual-vector adenoassociated virus and transcriptional silencing of mutant alleles. Furthermore, protein-based approaches to increase factor FVIII levels in VWD-type 3 or 2N patients are discussed. Finally, antibody-based options to interfere with VWF degradation (for congenital VWD-type 2A or acquired von Willebrand syndrome-type 2A) or increase endogenous VWF levels (for VWD-type 1) are presented. By highlighting these potential strategies, we hope to initiate an innovative path, which ultimately would allow us to better serve VWD patients and their specific needs.

Toward Personalized Treatment for Patients with Low von Willebrand Factor and Quantitative von Willebrand Disease

The biological mechanisms involved in the pathogenesis of type 2 and type 3 von Willebrand disease (VWD) have been studied extensively. In contrast, although accounting for the majority of VWD cases, the pathobiology underlying partial quantitative VWD has remained somewhat elusive. However, important insights have been attained following several recent cohort studies that have investigated mechanisms in patients with type 1 VWD and low von Willebrand factor (VWF), respectively. These studies have demonstrated that reduced plasma VWF levels may result from either (1) decreased VWF biosynthesis and/or secretion in endothelial cells and (2) pathological increased VWF clearance. In addition, it has become clear that some patients with only mild to moderate reductions in plasma VWF levels in the 30 to 50 IU/dL range may have significant bleeding phenotypes. Importantly in these low VWF patients, bleeding risk fails to correlate with plasma VWF levels and inheritance is typically independent of the VWF gene. Although plasma VWF levels may increase to > 50 IU/dL with progressive aging or pregnancy in these subjects, emerging data suggest that this apparent normalization in VWF levels does not necessarily equate to a complete correction in bleeding phenotype in patients with partial quantitative VWD. In this review, these recent advances in our understanding of quantitative VWD pathogenesis are discussed. Furthermore, the translational implications of these emerging findings are considered, particularly with respect to designing personalized treatment plans for VWD patients undergoing elective procedures.

Von Willebrand Factor Multimer Densitometric Analysis: Validation of the Clinical Accuracy and Clinical Implications in Von Willebrand Disease

Von Willebrand factor (VWF) multimer analysis is important in the classification of von Willebrand disease (VWD). Current visual VWF multimer analysis is time consuming and inaccurate in detecting subtle changes in multimer patterns. Although VWF multimer densitometric analysis may be useful, the accuracy needs further investigation before it can be widely applied. In this study we aimed to validate VWF multimer densitometric analysis in a large cohort of VWD patients and to identify patient characteristics associated with densitometric outcomes. Patients were included from the Willebrand in the Netherlands (WiN) study, in which a bleeding score (BS) was obtained, and blood was drawn. For multimer analysis, citrated blood was separated on an agarose gel and visualized by Western blotting. IMAGEJ was used to generate densitometric images and medium-large VWF multimer index was calculated. We included 560 VWD patients: 328 type 1, 211 type 2, and 21 type 3 patients. Medium-large VWF multimer index performed excellent in distinguishing visually classified normal VWF multimers from reduced high-molecular-weight (HMW) multimers (area under the curve [AUC]: 0.96 [0.94-0.98], P < 0.001), normal multimers from absence of HMW multimers (AUC 1.00 [1.00-1.00], P < 0.001), and type 2A and 2B from type 2M and 2N (AUC: 0.96 [0.94-0.99], P < 0.001). Additionally, higher medium-large VWF multimer index was associated with lower BS in type 1 VWD: β = -7.6 (-13.0 to -2.1), P = 0.007, adjusted for confounders. Densitometric analysis of VWF multimers had an excellent accuracy compared with visual multimer analysis and may contribute to a better understanding of the clinical features such as the bleeding phenotype of VWD patients.

Major differences in clinical presentation, diagnosis and management of men and women with autosomal inherited bleeding disorders

BACKGROUND

In recent years, more awareness is raised about sex-specific dilemmas in inherited bleeding disorders. However, no large studies have been performed to assess differences in diagnosis, bleeding phenotype and management of men and women with bleeding disorders. Therefore, we investigated sex differences in a large cohort of well-defined patients with autosomal inherited bleeding disorders (von Willebrand disease (VWD), rare bleeding disorders (RBDs) and congenital platelet defects (CPDs)).

METHODS

We included patients from three nationwide cross-sectional studies on VWD, RBDs and CPDs in the Netherlands, respectively the WiN, RBiN and TiN study. In all studies a bleeding score (BS) was obtained, and patients filled in an extensive questionnaire on the management and burden of their disorder.

FINDINGS

We included 1092 patients (834 VWD; 196 RBD; 62 CPD), of whom 665 (60.9%) were women. Women were more often referred because of a bleeding diathesis than men (47.9% vs 36.6%, p = 0.002). Age of first bleeding was similar between men and women, respectively 8.9 ± 13.6 (mean ±sd) years and 10.6 ± 11.3 years (p = 0.075). However, the diagnostic delay, which was defined as time from first bleeding to diagnosis, was longer in women (11.6 ± 16.4 years) than men (7.7 ± 16.6 years, p = 0.002). Similar results were found when patients referred for bleeding were analyzed separately. Of women aging 12 years or older, 469 (77.1%) had received treatment because of sex-specific bleeding.

INTERPRETATION

Women with autosomal inherited bleeding disorders are more often referred for bleeding, have a longer diagnostic delay, and often require treatment because of sex-specific bleeding.

FUNDING

The WiN study was supported (in part) by research funding from the Dutch Hemophilia Foundation (Stichting Haemophilia), Shire (Takeda), and CSL Behring (unrestricted grant).

Effectiveness and safety of hFVIII/VWF concentrate (Voncento®) in patients with inherited von Willebrand disease requiring surgical procedures: the OPALE multicentre observational study

BACKGROUND

In patients with moderate to severe qualitative and quantitative von Willebrand disease (VWD), even minor surgical procedures can be associated with a risk of life-threatening bleeding. Treatment strategies vary according to the levels of von Willebrand factor (VWF) and Factor VIII (FVIII). The aim of this study was to evaluate the effectiveness and the safety of Voncento^® (CSL Behring, Marburg, Germany), a plasma-derived FVIII/VWF concentrate (ratio 1:2.4), during surgeries performed in patients with inherited VWD.

MATERIALS AND METHODS

The OPALE study, a French multicentre observational study, was carried out from May 2016 to May 2019. It evaluated and analysed patients with inherited VWD (any type) requiring treatment with Voncento^® who underwent surgery.

RESULTS

In total, 92 patients were enrolled, and 66 patients underwent 100 surgical procedures: 69 minor and 31 major surgeries conducted in 30 patients with type 1, 50 patients with type 2, and 20 patients with type 3 VWD. During minor surgeries, the median number of infusions was one (range: 1-9), the pre-operative loading dose was 41 IU VWF:RCo kg^-1 (range: 18-147), and the total dose was 63 (range: 18-594). During major surgeries, the number of infusions was 4 (range: 1-23), the pre-operative loading dose was 43 (range: 25-66) IU VWF: RCo kg^-1, and the total dose was 155 (range: 40-575). The median FVIII:C levels ranged from 78 to 165 IU dL^-1 during 5 days after minor surgeries and from 86 and 167 IU dL^-1 during 11 days after major surgeries. VW:RCo levels ranged between 35 and 65 IU dL^-1 and between 34 and 76 IU dL^-1 after minor and major surgeries, respectively. The overall clinical effectiveness was qualified as "excellent" or "good" in 99% of patients. No thrombotic events related to Voncento^® were recorded.

DISCUSSION

The present study suggests that Voncento^® is an effective and well-tolerated therapy for the peri-operative management of patients with all VWD types.

von Willebrand factor and factor VIII levels after desmopressin are associated with bleeding phenotype in type 1 VWD

The bleeding phenotype of patients with type 1 von Willebrand disease (VWD) is very heterogeneous. We hypothesized that this heterogeneity may partly be explained by variability in response of von Willebrand factor (VWF) and factor VIII (FVIII) levels to stress during hemostatic challenges. We therefore investigated whether VWF and FVIII levels after administration of desmopressin, which mimic in vivo hemostatic response during hemostatic challenges, explain the heterogeneity in bleeding phenotype of patients with type 1 VWD. We performed a retrospective cohort study in 122 patients with type 1 VWD. All patients received a test dose of desmopressin shortly after diagnosis. Patients' mean age was 47 ± 14 years, and the mean Tosetto bleeding score was 10 ± 7. Higher FVIII activity during the complete time course after desmopressin administration (1, 3, and 5-6 hours), and higher VWF and FVIII levels combined at 3 hours after desmopressin administration, were associated with a lower bleeding score: β = -0.9 (-1.7; -0.1) and β = -1.2 (-1.9; -0.5), respectively, adjusted for age, sex, body mass index (BMI), and comorbidities. Patients with FVIII activity in the highest quartile 3 hours after desmopressin administration had a much lower bleeding score compared with patients in the other 3 quartiles (β = -5.1 [-8.2; -2.0]) and also had a lower chance of an abnormal bleeding score (odds ratio = 0.2 [0.1-0.5]), both adjusted for age, sex, BMI, and comorbidities. In conclusion, VWF and FVIII levels after desmopressin administration, which mimic hemostatic response to hemostatic challenges, are associated with the bleeding phenotype of patients with type 1 VWD. This may partly explain the variability in bleeding phenotype of these patients.

Ex vivo Improvement of a von Willebrand Disease Type 2A Phenotype Using an Allele-Specific Small-Interfering RNA

Von Willebrand disease (VWD) is the most common inherited bleeding disorder and is mainly caused by dominant-negative mutations in the multimeric protein von Willebrand factor (VWF). These mutations may either result in quantitative or qualitative defects in VWF. VWF is an endothelial protein that is secreted to the circulation upon endothelial activation. Once secreted, VWF multimers bind platelets and chaperone coagulation factor VIII in the circulation. Treatment of VWD focuses on increasing VWF plasma levels, but production and secretion of mutant VWF remain uninterrupted. Presence of circulating mutant VWF might, however, still affect normal hemostasis or functionalities of VWF beyond hemostasis. We hypothesized that inhibition of the production of mutant VWF improves the function of VWF overall and ameliorates VWD phenotypes. We previously proposed the use of allele-specific small-interfering RNAs (siRNAs) that target frequent VWF single nucleotide polymorphisms to inhibit mutant VWF . The aim of this study is to prove the functionality of these allele-specific siRNAs in endothelial colony-forming cells (ECFCs). We isolated ECFCs from a VWD type 2A patient with an intracellular multimerization defect, reduced VWF collagen binding, and a defective processing of proVWF to VWF. After transfection of an allele-specific siRNA that specifically inhibited expression of mutant VWF, we showed amelioration of the laboratory phenotype, with normalization of the VWF collagen binding, improvement in VWF multimers, and enhanced VWF processing. Altogether, we prove that allele-specific inhibition of the production of mutant VWF by siRNAs is a promising therapeutic strategy to improve VWD phenotypes.

Post-operative of bleeding, haemolysis and coagulation in mechanical circulatory support patients

There are unique complications arising from mechanical support devices but some of the long-term systemic haematological complications are indistinguishable from management problems affecting the care of other patients receiving intermediate to long term care in the cardiac ICU. The field of mechanical cardiac assist device (MCAD) is evolving. Despite major changes in design of these devices the most feared haematological complications have remained unchanged, namely haemolysis, pump thrombosis or thromboembolism. This review article gives an overview over the pathophysiology of MCAD related haematological complications, their management and where possible an outlook on future strategies to prevent such complications. The impact of MCAD on blood is discussed, starting with rheology, common pump mechanisms, current and future pump surface coating materials, anatomical considerations of the connection of the circuit and design of the circuit itself. Moreover, the duration of the cardiovascular support, impact of bleeding complications and other patient factors. This article also covers the impact of long term mechanical cardiac support on the properties of platelets, the anticoagulation strategies and a basic guide to the differential diagnosis of haemolysis is reviewed. The section on anaemia considers anaemia in the wider perioperative setting for patients in critical care having undergone cardiac surgery and also discusses transfusion alternatives.

New developments in von Willebrand disease

Von Willebrand disease (VWD) constitutes the most common inherited human bleeding disorder. It is associated with a mucocutaneous bleeding phenotype that can significantly impact upon quality of life. Despite its prevalence and associated morbidity, the diagnosis and subclassification of VWD continue to pose significant clinical challenges. This is in part attributable to the fact that plasma von Willebrand factor (VWF) levels vary over a wide range in the normal population, together with the multiple different physiological functions played by VWF in vivo. Over recent years, substantial progress has been achieved in elucidating the biological roles of VWF. Significant advances have also been made into defining the pathophysiological mechanisms underpinning both quantitative and qualitative VWD. In particular, several new laboratory assays have been developed that enable more precise assessment of specific aspects of VWF activity. In the present review, we discuss these recent developments in the field of VWD diagnosis, and consider how these advances can impact upon clinical diagnostic algorithms for use in routine clinical practice. In addition, we review some important recent advances pertaining to the various treatment options available for managing patients with VWD.