Management of von Willebrand disease with factor VIII/von Willebrand factor concentrates: results from current studies and surveys

Switch to pdVWF:pdFVIII concentrate for prophylaxis in a paediatric patient with Type 3 von Willebrand disease: a case report

OBJECTIVES

To report the long-term prophylaxis management of a child with type 3 von Willebrand disease by switching to Wilate (Octapharma AG), a plasma-derived, double virus-inactivated concentrate of freeze-dried of a 1 to 1 ratio of active Von Willebrand Factor and Factor VIII (pdVWF:pdFVIII) recently marketed as Eqwilate in France.

METHODS

This is a case report of 12.6-year-old boy with congenital Type 3 VWD who had a history of frequent bleeds. Prophylaxis started at the age of 38 months with FVIII-poor pdVWF concentrate (Wilfactin, LFB) and FVIII (Wilstart, LFB). Pharmacokinetics and thrombin generation assay were performed. Annualized bleeding rate was derived from the bleeding episodes documented in the medical record during a 24-month period before and after starting pdVWF:pdFVIII concentrate.

RESULTS

Both product injections promptly raised the endogenous thrombin potential (ETP). However, the maximal concentration of formed thrombin was higher following pdVWF:pdFVIII injection. Due to a high bleeds frequency and better results regarding FVIII levels and thrombin generation, the prophylaxis regimen was changed to the same dose and frequency of pdVWF:pdFVIII concentrate (42 IU/kg per day, three times a week). During the last 24 months, annualized total, trauma, and spontaneous bleeding rates were 7.5, 4.5, and 3, respectively. These rates decreased to 2, 1.5, and 0.5 respectively during the next two years. The mother reported a marked improvement in the quality of life of his son and hers.

CONCLUSION

Switch to pdVWF:pdFVIII concentrate for long-term prophylaxis in a young type 3 VWD patient was safe and effective in reducing bleeds.

Management of large volume liposuction in lipedema patients with von Willebrand disease: A systematic review and treatment algorithm

BACKGROUND

When performing large volume liposuction, perioperative management of lipedema patients with coagulation disorders remains challenging due to a lack of clinical experience. With a prevalence of 1% of von Willebrand disease (VWD) in the general population, basic knowledge on diagnostic and adapted surgical strategies are essential for patients' safety.

OBJECTIVE

Based on a selective literature review, the purpose of this article is to present a standardized algorithm for diagnosis and perioperative treatment of VWD patients undergoing large volume liposuction.

METHODS

The databases MEDLINE (via PubMed) and Web of Science were selectively searched with the term "(((liposuction) OR (surgery)) OR (lipectomy)) AND (((VWD) OR (hemostaseology)) OR (von Willebrand disease))". Included were articles published in English or German until November 2020.

RESULTS

The evidence for large volume liposuctions in patients with VWD is limited. Experience is largely based on operations with similar bleeding risks. A safe performance requires an adjustment of the surgical technique and a customized perioperative drug substitution plan. According to the current literature, perioperative thromboembolic events appear to be rare with adequate drug treatment.

CONCLUSION

The implementation of the developed diagnostic and treatment algorithm may help further reducing bleeding complications and improve the safety for treated patients.

Administration of plasma-derived coagulation factor VIII during the perioperative period of mastectomy for breast cancer with acquired von Willebrand syndrome

Background

Acquired von Willebrand syndrome (aVWS) is a rare bleeding disorder with laboratory findings similar to those of congenital von Willebrand disease (VWD). Patients with aVWS may require prophylactic treatment to prevent excessive bleeding following surgery. To our knowledge, to date, there have been no reports on perioperative management for breast cancer patients with aVWS.

Case presentation

A 60-year-old woman with breast cancer was diagnosed with aVWS due to polycythemia vera. Pre-operative laboratory testing showed a high platelet count and low von Willebrand factor (VWF) activity. The VWF activity did not improve despite an attempt to suppress platelet count with hydroxyurea. Therefore, we decided to perioperatively supplement with plasma-derived factor VIII (FVIII) containing von Willebrand factor (FVIII/VWF concentrates) to perform curative surgery for breast cancer safely. Consequently, the patient did not develop hemorrhage during/after surgery and was discharged on postoperative day 7, as planned, without problems.

Conclusions

For a patient with aVWS, which carries a high risk of hemorrhage during the perioperative period, initiation of appropriate management like supplementation of FVIII/VWF concentrates might enable safe curative surgery for breast cancer, and collaboration with the hematology department is critical.

Pharmacokinetics-based clinical management of acquired von Willebrand syndrome: a case report

von Willebrand disease (VWD) is a common bleeding disorder caused by defective or low levels of von Willebrand factor (VWF). Although most cases of VWD are caused by genetic mutations, some are acquired due to various disease states. In managing VWD, the aim is to normalize plasma levels of both VWF and factor VIII (FVIII), as this aids in hemostasis. Desmopressin usually corrects VWF level in type 1 VWD by inducing the release of endogenous VWF. In cases where desmopressin is ineffective or cannot be used, transfusion of virally inactivated, plasma-derived VWF/FVIII concentrate or infusion of recombinant VWF (Vonvendi) is indicated. Treatment of acquired von Willebrand syndrome (AVWS) aims to control the underlying disease while regulating life-threatening hemorrhages with infusions of VWF/FVIII concentrate. Wide intrasubject variability in VWF and FVIII levels, particularly in AVWS, necessitates verification of response to treatment by frequent monitoring of the plasmatic VWF level. Clinical pharmacokinetics of VWF may facilitate calculation of the necessary loading and maintenance doses of VWF/FVIII concentrate in the management of AVWS patients undergoing surgery, thereby avoiding unnecessary infusion of coagulation factor concentrate.

Efficacy and safety of a new generation von Willebrand factor/factor VIII concentrate (Wilate®) in the management of perioperative haemostasis in von Willebrand disease patients undergoing surgery

The aim of this study was to assess the efficacy of Wilate®, a new generation, plasma-derived, high-purity, double virus-inactivated von Willebrand factor (VWF) and factor VIII (FVIII) concentrate (ratio close to physiological 1:1) in the perioperative management of haemostasis in von Willebrand disease (VWD). Data for VWD patients who received Wilate® for perioperative management were obtained from four European, prospective, open-label, non-controlled, non-randomised, multicentre phase II or III clinical trials. A total of 57 surgical procedures were performed (major: n = 27; minor n = 30) in 32 patients. The majority of patients (n = 19, 59.4%) had type 3 VWD, 9 (28.1%) had type 2 VWD and four (12.5%) had type 1 VWD. During major surgery, median daily FVIII dose and mean number of infusions were 25 IU•kg-1 FVIII (VWF:RCô23 IU•kg-1) and 11.0, respectively. Corresponding values for minor surgery were 35 IU•kg-1 (VWF:RCo ~32 IU•kg-1) and 1.5. The efficacy of Wilate® was rated by the investigator as excellent or good in 51 of 53 (96%) procedures. Tolerability was rated as very good or good in 100% of major surgeries (27 of 27) and minor surgeries (29 of 29). Wilate® is an effective and well-tolerated VWF/FVIII replacement therapy in the perioperative management of haemostasis in patients with VWD. It can be administered at a similar FVIII dose, but at a lower VWF dose, as compared to older generation products. Clinical benefits were shown in a population with a high proportion of type 3 VWD patients.

Diagnosis, prevention, and management of bleeding episodes in Philadelphia-negative myeloproliferative neoplasms: recommendations by the Hemostasis Working Party of the German Society of Hematology and Medical Oncology (DGHO) and the Society of Thrombosis and Hemostasis Research (GTH)

Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPN) comprise a heterogeneous group of chronic hematologic malignancies. The quality of life, morbidity, and mortality of patients with MPN are primarily affected by disease-related symptoms, thromboembolic and hemorrhagic complications, and progression to myelofibrosis and acute leukemia. Major bleeding represents a common and important complication in MPN, and the incidence of such bleeding events will become even more relevant in the future due to the increasing disease prevalence and survival of MPN patients. This review discusses the causes, differential diagnoses, prevention, and management of bleeding episodes in patients with MPN, aiming at defining updated standards of care in these often challenging situations.

Hemostatic efficacy, safety, and pharmacokinetics of a recombinant von Willebrand factor in severe von Willebrand disease

This phase 3 trial evaluated the safety and hemostatic efficacy of a recombinant von Willebrand factor (rVWF) for treatment of bleeds in severe von Willebrand disease (VWD). rVWF was initially administered together with recombinant factor VIII (rFVIII) and subsequently alone, as long as hemostatic factor VIII activity (FVIII : C) levels were maintained. Pharmacokinetics (PK) were evaluated in a randomized cross-over design (rVWF vs rVWF:rFVIII at 50 IU VWF:ristocetin cofactor activity [RCo]/kg). Bleed control for all treated bleeds (N = 192 bleeds in 22 subjects) was rated good or excellent (96.9% excellent; 119 of 122 minor, 59 of 61 moderate, and 6 of 7 major bleeds) on a 4-point scale (4 = none to 1 = excellent). A single infusion was effective in 81.8% of bleeds. Treatment success, defined as the number of subjects with a mean efficacy rating of <2.5, was 100%. The PK profile of rVWF was not influenced by rFVIII (mean VWF:RCo terminal half-life: 21.9 hours for rVWF and 19.6 hours for rVWF:rFVIII). FVIII : C levels increased rapidly after rVWF alone, with hemostatic levels achieved within 6 hours and sustained through 72 hours after infusion. Eight adverse events (AEs; 6 nonserious AEs in 4 subjects and 2 serious AEs [chest discomfort and increased heart rate, without cardiac symptomatology] concurrently in 1 subject) were associated with rVWF. There were no thrombotic events or severe allergic reactions. No VWF or FVIII inhibitors, anti-VWF binding antibodies, or antibodies against host cell proteins were detected. These results show that rVWF was safe and effective in treating bleeds in VWD patients and stabilizes endogenous FVIII : C, which may eliminate the need for rFVIII after the first infusion. This trial was registered at www.clinicaltrials.gov as #NCT01410227.

Update on von Willebrand factor multimers: focus on high-molecular-weight multimers and their role in hemostasis

Normal hemostasis requires von Willebrand factor (VWF) to support platelet adhesion and aggregation at sites of vascular injury. VWF is a multimeric glycoprotein built from identical subunits that contain binding sites for both platelet glycoprotein receptors and collagen. The adhesive activity of VWF depends on the size of its multimers, which range from 500 to over 10 000 kDa. There is good evidence that the high-molecular-weight multimers (HMWM), which are 5000-10 000 kDa, are the most effective in supporting interaction with collagen and platelet receptors and in facilitating wound healing under conditions of shear stress. Thus, these HMWM of VWF are of particular clinical interest. The unusually large multimers of VWF are, under normal conditions, cleaved by the plasma metalloproteinase ADAMTS13 to smaller, less adhesive multimers. A reduction or lack of HMWM, owing to a multimerization defect of VWF or to an increased susceptibility of VWF for ADAMTS13, leads to a functionally impaired VWF and the particular type 2A of von Willebrand disease. This review considers the biology and function of VWF multimers with a particular focus on the characterization of HMWM - their production, storage, release, degradation, and role in normal physiology. Evidence from basic research and the study of clinical diseases and their management highlight a pivotal role for the HMWM of VWF in hemostasis.

Improved performance characteristics of the von Willebrand factor ristocetin cofactor activity assay using a novel automated assay protocol

BACKGROUND, OBJECTIVES AND METHODS: An accurate, sensitive and precise assay for reliable determination of the ristocetin cofactor activity of von Willebrand factor (VWF:RCo) in plasma and von Willebrand Factor (VWF)-containing concentrates has been evaluated. The assay is based on a commercially available automated protocol with modifications including a combination of adding additional ristocetin and the use of two calibration curves for the high and low measuring ranges.

RESULTS

 Addition of extra ristocetin resulted in improved measurement of VWF recoveries from various VWF-containing concentrates that were underestimated using the standard automated protocol. The modifications resulted in improved assay performance over an extended measuring range (2.00-0.03 IUmL(-1) ). Accuracy was tested using VWF deficiency plasma spiked with the 1st international standard (IS) for VWF concentrate. Seven dilutions, ranging from 1.80 to 0.05IUmL(-1) , were analyzed and resulted in measured concentrations between 80% and 100% of the assigned potency of the standard. Linearity was determined from the regression plot of the same concentrate dilutions and resulted in a correlation coefficient of 0.998. The repeatability, expressed as coefficient of variation, was 2% in the normal range (0.90IUmL(-1) ) and 8% at the level of 0.05IUmL(-1) . The corresponding reproducibility results were 2% and 15% at the normal and low measuring ranges, respectively.

CONCLUSIONS

 Analysis of patients with von Willebrand disease (VWD) indicates that the modified automated BCS(®) protocol has a superior discrimination power compared with the standard protocol. This is especially true in samples with low VWF, as in patients with type 3 VWD.

Hemostatic and hemorrhagic problems in neurosurgical patients

BACKGROUND

Abnormalities of the hemostasis can lead to hemorrhage, and on the other hand to thrombosis. Intracranial neoplasms, complex surgical procedures, and head injury have a specific impact on coagulation and fibrinolysis. Moreover, the number of neurosurgical patients on medication (which interferes with platelet function and/or the coagulation systems) has increased over the past years.

METHOD

The objective of this review is to recall common hemostatic disorders in neurosurgical patients on the basis of the "new concept of hemostasis". Therefore the pertinent literature was searched to provide a structured and up to date manuscript about hemostasis in Neurosurgery.

FINDINGS

According to recent scientific publications abnormalities of the coagulation system are discussed. Pathophysiological background and the rational for specific (cost)-effective perioperative hemostatic therapy is provided.

CONCLUSIONS

Perturbations of hemostasis can be multifactorial and maybe encountered in the daily practice of neurosurgery. Early diagnosis and specific treatment is the prerequisite for successful treatment and good patients outcome.

Progress in large-scale purification of factor VIII/von Willebrand factor concentrates using ion-exchange chromatography

BACKGROUND AND OBJECTIVES

We investigated and optimized the parameters of a chromatographic process suitable for industrial scale to obtain a highly purified factor VIII (FVIII)/von Willebrand factor (VWF) concentrate.

MATERIALS AND METHODS

Several chromatographic runs were performed on the same production intermediate using different anion-exchange supports. The best matrix was selected and the final product was characterized. Once the chromatographic medium was chosen, the other parameters were evaluated to obtain the highest purified product and to modulate the VWF content in the FVIII/VWF complex.

RESULTS

Fractogel EMD TMAE was the best support among those tested. It was the only one maintaining good results either with standard or double loading and flow rate conditions with respect to a typical industrial process. The chromatographic recovery of FVIII co-purified with VWF was at least 86% with a specific activity not lower than 140 IU/mg. The FVIII/VWF complex obtained is highly pure and, with the exception of immunoglobulin M (IgM), all investigated contaminant proteins are under the detection limit. Different concentrates characterized by variable FVIII/VWF ratios were purified by varying the chromatographic conditions.

CONCLUSIONS

Several highly purified products, suitable for haemophilia A and von Willebrand disease management, can be obtained, through the same chromatographic process, on an industrial scale.

Prophylaxis of bleeding episodes in patients with von Willebrand's disease

Patients with severe forms of von Willebrand's disease (VWD) may have frequent haemarthroses, especially when factor VIII (FVIII) levels are below 10 U/dL, so that some of them develop target joints like patients with severe haemophilia A. Some patients have recurrent gastrointestinal bleeding, often without lesions in the gastrointestinal tract, and need treatment every day or every other day. Finally, there are children who have epistaxis frequently and severely enough to cause anaemia. In these frequent and severe bleeders, the optimal therapy may be secondary long-term prophylaxis with von Willebrand factor (VWF)/FVIII concentrates rather than on-demand treatment on the occasion of bleeding episodes. The largest experience on such prophylaxis in VWD has been in Sweden in 35 patients with severe forms of VWD. Long-term prophylaxis was also implemented in a cohort of Italian patients with VWD: prophylaxis was used in seven patients with types 3 (n = 1 ), 2A (n = 4), 2M (n = 1) and type 1 (n = 1) VWD because of recurrent gastrointestinal bleeds and in four patients with type 3 VWD because of joint bleeds. Prophylaxis prevented bleeding completely in eight patients and largely reduced hospitalisation for blood transfusions in the remaining three. The cost-effectiveness of these prophylaxis regimens versus on-demand therapy will now be investigated in one large international study

A systematic overview of the first pasteurised VWF/FVIII medicinal product, Haemate P/ Humate -P: history and clinical performance

Patients with von Willebrand disease (VWD) and haemophilia A (HA) lack, to varying degrees, the von Willebrand factor (VWF) and coagulation factor VIII (FVIII) that are critical for normal haemostasis. These conditions in turn make patients prone to uncontrolled bleeding. Historically, patients with severe forms of VWD or HA were crippled before adulthood and their life expectancy was significantly reduced. Over the past decades, specific coagulation factor replacement therapies including Haemate P, have been developed to help patients achieve and maintain normal haemostasis. Haemate P is a human, plasma-derived VWF/FVIII medicinal product, which was first licensed in Germany in 1981 for the treatment of HA-associated bleeding. It has since then come to be accepted as the gold standard for both the treatment and prophylaxis of bleeding in VWD, especially in cases where desmopressin [1-deamino-8-D-arginine vasopressin (DDAVP)] has been ineffective. Haemate P was the first effectively virus-inactivated (pasteurisation: 60 degrees C for 10 h in aqueous solution) FVIII product, whereby the risk of potentially threatening infective complications of plasma-derived products was reduced. Haemate P was also shown to have a VWF multimer profile remarkably close to that of normal plasma. This bibliographic review presents previously unpublished clinical data of Haemate P, based upon internal clinical study reports of the proprietor, CSL Behring, in addition to data already presented in other publications. The data demonstrate a predictable and well-characterised pharmacokinetic profile, and a proven record of short- and long-term safety, while effectively correcting the haemostatic defects in VWD and HA. Recently available data have also shown Haemate P to be of haemostatic value in exceptional clinical circumstances including surgical interventions. By virtue of its plasma-derived combination of VWF and FVIII, in addition to its high VWF:FVIII content ratio (2.4:1), Haemate P is also associated with successful immune tolerance induction in those patients developing inhibitor antibodies. Although the theoretical risk of thromboembolic complications does exist while receiving Haemate P, as it does with any FVIII replacement therapy, the incidence of such complications has remained notably low. Given the robust data that have accumulated for the use of Haemate P, dosing recommendations are also described in this review; the recommendations are tailored to patient-specific contexts including baseline VWF and FVIII levels in plasma and the type of surgical intervention being undertaken. A wide variety of studies have also provided data on paediatric and geriatric populations, all of which have suggested that Haemate P can be safely and effectively used in a wide variety of clinical circumstances.

Highly purified VWF/FVIII concentrates in the treatment and prophylaxis of von Willebrand disease: the PRO. WILL Study

Two therapeutic approaches are available to manage patients with von Willebrand disease (VWD): (i) the release of endogenous von Willebrand factor (VWF) from endothelial compartments induced by desmopressin (DDAVP); (ii) the transfusion of exogenous VWF contained in VWF/FVIII plasma-derived concentrates. Only a few high-purity VWF/FVIII concentrates have been extensively evaluated in pharmacokinetic (PK) trials as well as in retrospective or prospective efficacy studies in VWD. The Alphanate Study Group published results of PK and clinical efficacy studies in 2002. Efficacy results showed that 75% of bleeding episodes were controlled with one or two infusions, and 71% of patients who received prophylactic treatment for surgeries or invasive procedures had good clinical responses. In another retrospective study, 22 VWD patients in Italy received Fanhdi, a VWF concentrate similar to Alphanate. Excellent-good clinical responses were seen in 92% of bleeding episodes and in 93% of surgical procedures. More recently, the efficacy and safety of Fanhdi have been evaluated retrospectively in a larger cohort of Italian patients (n = 103) with 97% (bleedings) and 99% (surgeries) of excellent/good clinical responses. The largest experience on secondary prophylaxis in VWD has been collected in Sweden in 35 patients with severe forms of VWD. Secondary prophylaxis was also implemented in a cohort of Italian patients with VWD. Prophylaxis was started because of GI bleeds in seven patients with types 3 (n = 1), 2A (n = 4), 2M (n = 1) and type 1 (n = 1) and for joint bleeds in four patients with type 3 VWD (n = 4). Prophylaxis prevented bleeding completely in eight patients and largely reduced hospitalization for blood transfusions in the remaining three. The cost-effectiveness of these prophylaxis regimens versus on demand therapy will be now investigated in one large prospective study (PRO.WILL) organized in Italy.

von Willebrand factor/factor VIII concentrate (Haemate P) dosing based on pharmacokinetics: a prospective multicenter trial in elective surgery

BACKGROUND

While plasma-derived concentrates containing large amounts of von Willebrand factor (VWF) are effective in treating von Willebrand disease (VWD), optimal dosing remains to be fully characterized.

OBJECTIVES

To determine the feasibility of dosing Haemate P VWF/factor VIII (FVIII) concentrate based on pharmacokinetics (PK) in the management of surgical subjects with VWD.

METHODS

VWD subjects scheduled for elective surgery were enrolled in a prospective multicenter open-label cohort study. A pre-operative loading dose of VWF/FVIII concentrate based upon prior individual subject PK analysis was administered followed by postoperative therapeutic/maintenance infusions.

RESULTS

Twenty-eight subjects with types 1, 2A or 3 VWD and one with type 2 M were enrolled. Median in vivo recovery of VWF ristocetin cofactor (VWF:RCo) was 1.9 IU dL(-1) (IU kg(-1))(-1) with an interquartile range (IQR) of 1.6-2.5 IU dL(-1) (IU kg(-1))(-1). Median response, half-life and clearance were 74.0% (IQR, 55.5-100%), 15.6 h (IQR, 9.0-28.4 h) and 3.26 mL kg(-1) h(-1) (IQR, 2.29-5.21 mL kg(-1) h(-1)), respectively. A PK-guided median VWF:RCo loading dose of 62.4 IU kg(-1) (IQR, 50.1-87.0 IU kg(-1)) was administered. Postoperative mean trough VWF:RCo levels of 62-73 IU dL(-1) were sufficient to prevent bleeding. Investigators rated hemostasis excellent or good in 96.3% of subjects on the day of surgery and 100% on the next day and on day 14. A subject with multiple risk factors developed pulmonary embolism, which resolved without sequelae.

CONCLUSIONS

Haemate P provided effective and safe hemostasis in VWD subjects undergoing elective surgery. Selection of Haemate P loading dose on the basis of VWF PK proved feasible.

Treatment of severe von Willebrand disease with a high-purity von Willebrand factor concentrate (Wilfactin): a prospective study of 50 patients

BACKGROUND AND OBJECTIVES

A plasma-derived von Willebrand factor (VWF) concentrate with low factor VIII (FVIII) content was specifically developed to treat von Willebrand disease (VWD). Efficacy and safety were investigated by merging the results of two comparable protocols conducted prospectively in 5 European and 12 French centers.

METHODS AND RESULTS

Fifty patients with clinically severe VWD (72% had VWF ristocetin cofactor activity less than 10 IU dL(-1) and 46% had FVIII < 20 IU dL(-1)) were treated with the concentrate as the only therapy, except for clinical situations requiring a priming dose of FVIII to rapidly correct an intrinsic coagulation defect. A total of 139 spontaneous bleeding episodes were treated; only 53 (38%) needed a concomitant FVIII dose. Outcome was excellent or good in 89% of the episodes. Forty-four patients underwent 108 surgical or invasive procedures. Outcome was excellent or good in 95 scheduled procedures (only VWF was infused) and 13 emergency procedures (a priming FVIII dose was co-administered with the first VWF infusion). There were no thrombotic complications and none of the 18 patients with type 3 VWD developed anti-VWF or anti-FVIII antibodies.

CONCLUSIONS

This concentrate safely and effectively provides hemostasis in patients with clinically severe VWD.

Peri-operative management of an adult patient with type 2N von Willebrand's disease scheduled for coronary artery bypass graft

We describe a patient with type 2N von Willebrand's disease scheduled for elective coronary artery bypass graft for severe three-vessel coronary artery disease with involvement of the left main stem. He was given a pre-operative bolus of 3000 IU factor VIII/Willebrand factor concentrate (approximately 40 IU.kg(-1)), followed by a continuous infusion of 3 IU.h(-1) (228 IU.h(-1)) before undergoing coronary surgery with full heparinisation and cardiopulmonary bypass. There were no intra-operative bleeding complications and only one unit of packed red blood cells was required postoperatively. Thromboprophylaxis with low-molecular weight heparin and aspirin was given and the infusion of factor VIII/von Willebrand factor concentrate continued for 2 days. As a result of haematological monitoring, heparin therapy was changed from prophylactic to therapeutic on day 5-6 and stopped on day 7.

Management of inherited von Willebrand disease in 2007

Von Willebrand disease (VWD) is the most frequent inherited bleeding disorder and is due to quantitative (types 1 and 3) or qualitative (type 2) defects of von Willebrand factor (VWF). VWD is inherited by autosomal dominant or recessive patterns, but women with mild forms are more symptomatic. VWD is classified in six VWD types (1, 2A, 2B, 2M, 2N, 3) with peculiar phenotype and genotype. The ristocetin cofactor activity (VWF:RCo) is the most useful test for VWD diagnosis, because it can mimic the interactions of VWF with its platelet receptor. Knowledge of the segments of VWF involved in the binding to its receptor and to factor VIII prompted the search for mutations in specific exons of the VWF gene, with mutations causing VWD types 2A, 2B, 2M, 2N localized in exons 18-28. In case of VWD types 1 and 3 the mutations are spread within the entire gene. Desmopressin (DDAVP) is the treatment of choice for type 1 VWD because it can induce release of normal VWF from cellular compartments. In type 3 and in severe forms of types 1 and 2 VWD, DDAVP is not effective and plasma virally inactivated VWF concentrates should be used in bleedings, surgery, and secondary long-term prophylaxis.

The 80th anniversary of von Willebrand's disease: history, management and research

The history of von Willebrand's disease (VWD) is fascinating because it demonstrates how good clinical observations, genetic studies and biochemical skills can improve basic understanding of a disease and its management. The continuous efforts of scientists and clinicians during the last 80 years have significantly improved the knowledge of von Willebrand factor (VWF) structure and function and the management of VWD. Diagnosis of phenotype and genotype is now available in many countries and treatment is becoming more specific according to the VWD type. Any therapeutic agents must correct the dual defect of haemostasis, i.e. the abnormal platelet adhesion due to reduced and/or dysfunctional and low levels of factor VIII (FVIII) associated with VWF defects. Desmopressin (DDAVP) is the treatment of choice for type 1 VWD because it induces release of VWF from cellular compartments. Plasma virally inactivated VWF concentrates containing FVIII are effective and safe in patients unresponsive to DDAVP. There are advanced plans to develop a recombinant VWF but this product will require the concomitant administration of FVIII for the control of acute bleeds. Basic research studies on cellular biology, biochemistry and immunology have confirmed the role of VWF as a crucial participant in both haemostasis and thrombosis as its main biological activity is to support platelet adhesion-aggregation in the circulation. Retrospective and prospective clinical research studies, including bleeding history and laboratory markers for diagnosis as well as the use of DDAVP and VWF concentrates to manage or prevent bleeds in patients with VWD have been essential to provide general guidelines for VWD management. The large number of publications quoting VWD and VWF emphasizes the important role of VWF in medicine.

Coagulation Defects

The present understanding of the coagulation process emphasizes the final common pathway and the proteolytic systems that result in the degradation of formed clots and the prevention of unwanted clot formations, as well as a variety of defense systems that include tissue repair, autoimmune processes, arteriosclerosis, tumor growth, the spread of metastases, and defense systems against micro-organisms. This article discusses diagnosis and management of some of the most common bleeding disorders. The goals are to provide a simple guide on how best to manage patients afflicted with congenital or acquired clotting abnormalities during the perioperative period, present a brief overview of the methods of testing and monitoring the coagulation defects, and discuss the appropriate pharmacologic or blood component therapies for each disease.

Von Willebrand's disease: clinical management

The aim of treatment of von Willebrand's disease (VWD) is to correct the dual defect of haemostasis, i.e. the abnormal platelet adhesion due to reduced and/or dysfunctional von Willebrand factor (VWF) and the abnormal coagulation expressed by low levels of factor VIII (FVIII). Desmopressin (DDAVP) is the treatment of choice for type 1 VWD because it can induce release of normal VWF from cellular compartments. Prospective studies on biological response versus clinical efficacy of DDAVP in VWD type 1 and 2 are in progress to further explore its benefits and limits as therapeutic option. In type 3 and in severe forms of type 1 and 2 VWD, DDAVP is not effective and for these patients plasma virally inactivated concentrates containing VWF and FVIII are the mainstay of treatment. Several intermediate- and high-purity VWF/FVIII concentrates are available and have been shown to be effective in clinical practice (bleeding and surgery). New VWF products almost devoid of FVIII are now under evaluation in clinical practice. Although thrombotic events are rare in VWD patients receiving repeated infusions of concentrates, there is some concern that sustained high FVIII levels may increase risk of postoperative venous thromboembolism. Dosage and timing of VWF/FVIII administrations should be planned to keep FVIII level between 50 and 150 U/dL. Appropriate dosage and timing in repeated infusions are also very important in patients exposed to secondary long term prophylaxis for recurrent bleedings.