The challenging management of a child with type 3 von Willebrand disease and antibodies to von Willebrand factor

Immune complications and their management in inherited and acquired bleeding disorders

Disorders of coagulation, resulting in serious risks for bleeding, may be caused by autoantibody formation or by mutations in genes encoding coagulation factors. In the latter case, antidrug antibodies (ADAs) may form against the clotting factor protein drugs used in replacement therapy, as is well documented in the treatment of the X-linked disease hemophilia. Such neutralizing antibodies against factors VIII or IX substantially complicate treatment. Autoantibody formation against factor VIII leads to acquired hemophilia. Although rare, antibody formation may occur in the treatment of other clotting factor deficiencies (eg, against von Willebrand factor [VWF]). The main strategies that have emerged to address these immune responses include (1) clinical immune tolerance induction (ITI) protocols; (2) immune suppression therapies (ISTs); and (3) the development of drugs that can improve hemostasis while bypassing the antibodies against coagulation factors altogether (some of these nonfactor therapies/NFTs are antibody-based, but they are distinct from traditional immunotherapy as they do not target the immune system). Choice of immune or alternative therapy and criteria for selection of a specific regimen for inherited and autoimmune bleeding disorders are explained. ITI serves as an important proof of principle that antigen-specific immune tolerance can be achieved in humans through repeated antigen administration, even in the absence of immune suppression. Finally, novel immunotherapy approaches that are still in the preclinical phase, such as cellular (for instance, regulatory T cell [Treg]) immunotherapies, gene therapy, and oral antigen administration, are discussed.

Towards novel treatment options in von Willebrand disease

Deficiency or dysfunction of von Willebrand factor (VWF) is associated with a bleeding disorder known as von Willebrand disease (VWD). The clinical manifestations of VWD are heterogeneous, and are in part dictated by the structural or functional defects of VWF. The tools to control bleeding in VWD are dominated by VWF concentrates, desmopressin and antifibrinolytic therapy. In view of these treatments being considered as effective, it is surprising that quality-of-life studies consistently demonstrate a significant mental and physical burden in VWD patients, particularly in women. Apparently, the current weaponry to support the management of VWD is insufficient to fully address the needs of the patients. It is important therefore to continue to search for innovative treatment options which could better serve the VWD patients. In this short review, two of such options are discussed in more detail: emicizumab to correct for the deficiency of factor VIII (FVIII), and the pegylated aptamer BT200 to increase endogenous levels of the VWF/FVIII complex.

Von Willebrand Disease: Current Status of Diagnosis and Management

Von Willebrand disease (VWD) is a common bleeding disorder, affecting male and female individuals equally, that often manifests in mucosal bleeding. VWD can be secondary to a quantitative (Type 1 and Type 3) or qualitative (Type 2) defects in Von Willebrand factor (VWF). Initial testing includes VWF antigen, as well as a platelet binding assay to differentiate between qualitative and quantitative defects. Further subtyping requires additional testing and is needed to ensure appropriate treatment. Desmopressin, antifibrinolytics, hormonal treatments for heavy menstrual bleeding, and VWF concentrates are commonly used in the treatment of VWD.

Monitoring of von Willebrand factor inhibitors in patients with type 3 von Willebrand disease using a quantitative assay

BACKGROUND

Antibodies inhibiting von Willebrand factor (VWF) develop in a subset of patients with type 3 von Willebrand disease (VWD3) and may be detected by their inhibition of ristocetin cofactor activity (VWF:RCo). Some also inhibit factor VIII activity (VIII:C).

AIM

To describe monitoring of ten VWD3 patients for VWF inhibitors using a quantitative assay.

METHODS

VWF inhibitor was measured by comparing VWF:RCo activity of a mix of patient and pooled normal plasma (PNP) with a mix of buffer and PNP, using agglutination of fixed normal platelets in microtiter plates or lyophilized platelets in an aggregometer. VIII:C inhibitor was measured by Bethesda assay. Preanalytical heat treatment of patient plasma was used during treatment episodes.

RESULTS

Four of 10 patients monitored developed VWF inhibitors, two detected during bleeding episodes refractory to treatment and two on routine screening. Data from the first five patients were used to establish an arbitrary unit, VWU, defined as the amount of inhibitor per millilitre of patient plasma inactivating 25% of the activity of 1 mL of PNP. In three of four patients, both VWF:RCo and VIIII:C were inhibited at some time points, although VIII:C inhibition sometimes disappeared. In one patient, no VIII:C inhibition was seen. Two patients remained inhibitor positive more than 15 years after inhibitor detection, one became negative following immune tolerance induction, and one was deceased.

CONCLUSIONS

VWF inhibitors can be quantitatively monitored in VWD3 patients. Preanalytical heat treatment may be required for their detection post infusion.

Efficacy of emicizumab in a pediatric patient with type 3 von Willebrand disease and alloantibodies

Type 3 von Willebrand disease with alloantibodies is a rare clinical entity with few treatment options. Emicizumab prophylaxis in such patients may result in improved hemarthrosis control, lower cost, and enhanced quality of life.

von Willebrand factor alloantibodies in type 3 von Willebrand disease

: The development of neutralizing antibodies is a rare complication of von Willebrand disease treatment. In major surgical procedures for severe forms of the disease, the recognition of ineffective therapy and alternative treatment protocols are lifesaving. We report the case of a 6-year-old girl with type 3 von Willebrand disease in whom inhibitors were sought due to ineffective haemostasis together with lower than expected von Willebrand factor (VWF) recoveries after a surgical procedure. Replacement therapy first with recombinant factor VIIa and then with high doses of recombinant factor VIII in continuous infusion successfully stopped the bleeding. A high level of anti-VWF antibodies was determined by the immunological method. A frameshift mutation associated with premature termination codon (c.2435delC, p.Pro812ArgfsTer31) was determined in our patient. Although the reports on association of this mutation with inhibitor risk are inconsistent, it represents an evidence-based diagnostic and management practice in recognition of high-risk VWF genotype.

Successful Desensitization of a Patient with Possible IgE-Mediated Anaphylactic Reaction to FVIII/VWF Concentrate

Background: Type 3 von Willebrand disease (VWD) is a severe bleeding disorder with a prevalence of 1:1 million live births. There are several von Willebrand factor (VWF) replacement products used in the treatment of acute bleeding episodes or as prophylaxis. Patients who receive multiple transfusions have an increased risk of developing antibodies against these products. These antibodies can lead to life-threatening anaphylactic reactions. Previous studies have identified immune complex formation and complement activation as the trigger for anaphylaxis, rather than IgE. IgE-mediated anaphylaxis against VWF concentrates has not yet been published. Case: A 4-year-old female patient with type 3 VWD was referred to our hospital because of an anaphylactic reaction during FVIII/VWF concentrate (Immunate^®) infusion. She had previously received FVIII/VWF concentrate (Haemate P^®) infusions 8 times without any complications. She did not have antibodies against VWF and FVIII, and serum IgA level was normal. Since she needed factor replacement therapy as a result of a growing hematoma on her scalp, we performed skin prick and intradermal tests 2 days after the reaction. The prick test, with FVIII/VWF (Immunate), was negative, but the intradermal test was positive. We administered a 12-step desensitization protocol with FVIII/VWF concentrate (Immunate) successfully without any reactions. Conclusion: Anaphylactic reaction to factor replacement products is a major problem for patients with VWD, especially type 3 VWD requiring multiple factor infusions. We achieved a successful desensitization with FVIII/VWF concentrate in a patient who had an anaphylactic reaction during the infusion of this product. Our patient is important since she represents the first case of IgE-mediated anaphylaxis against VWF concentrate reported in the literature.

Type 3 VWD and an inhibitor to VWF: Challenges in diagnosis

Developing an inhibitor to von Willebrand factor (VWF) is extremely uncommon. Consequently, patients with von Willebrand disease (VWD) tend not to be routinely evaluated for inhibitors, leading to the possibility of delay in inhibitor diagnosis. We present such an occurrence to raise awareness, with a view to avoiding such delays. A 1-year-old male with no family history of bleeding disorders or parental consanguinity presented with a tongue bleed lasting three days. Investigations confirmed a diagnosis of Type 3 VWD. Over the next few months, the patient received seven exposures to Humate-P (a plasma derived FVIII containing von Willebrand factor concentrate), but developed an anaphylactic reaction necessitating adrenalin and Benadryl (diphenhydramine). The reaction quickly abated and did not recur with further exposure to Humate-P. In 2013, due to recurrent epistaxis and tonsillar bleeding, the patient was commenced on prophylaxis receiving Humate-P 50 RCo U/kg twice weekly. Despite this regimen, he continued to experience recurrent epistaxis, leading to escalation of prophylaxis to 3/week. In November 2014, he showed persistent tonsillar bleeding, despite having received two doses of Humate-P (each 40 RCo U/kg) in the previous 12 hours. Testing revealed reduced VWF:Ag, VWF:RCo and FVIII:C recoveries. Further testing revealed an anti-VWF antibody (2.6 BU) of unspecified Ig type. Since diagnosis of the inhibitor, he has received 100 RCo U/kg daily for prophylaxis and immune tolerance. He is now bleed-free; however, monthly inhibitor testing shows that his inhibitor persists. Given the limited experience and literature on inhibitors in VWD, the prognosis for such cases is unknown.

Efficacy of Octocog Alfa (Advate) in a Child with Type 3 von Willebrand Disease and Alloantibodies

Von Willebrand disease (VWD) is the most frequent inherited bleeding disorder and is caused by either a quantitative and/or qualitative defect of the multimeric glycoprotein vonWillebrand factor (VWF).[...].

Skin testing, graded challenge, and desensitization to von Willebrand factor (VWF) products in type III von Willebrand disease (VWD)

This is the first report of skin testing, graded challenge and desensitization for VWF replacement products in patients with VWF deficiency. Patients who have experienced reactions to VWF products may benefit from these protocols.

Management of VWD

VWD is the most common inherited bleeding disorder known. It is caused by a deficiency or dysfunction of the VWF molecule. Bleeding risk varies between modest increases in bleeding seen only with procedures to major risk of spontaneous hemorrhage depending upon the type of VWD. The treatment approach to VWD has changed little in the past 2 decades, but there are numerous subtleties in optimal management. Management includes the prevention or treatment of bleeding by raising endogenous VWF levels with medications such as desmopressin or providing exogenous VWF concentrates. Fibrinolytic inhibitors and topical hemostatic agents are also effective adjunctive measures. Bleeding specific to women presents a special challenge because of heavy menstrual bleeding and pregnancy. Successful management of pregnancy in patients with VWD involves coordination with obstetrics, anesthesia, and the coagulation laboratory monitoring VWF:RCo and FVIII:C levels. Prophylactic treatment with VWF concentrates is emerging as an effective preventive therapy in patients with severe disease. Antibodies to VWF present a special challenge in the management of rare patients with type 3 disease. New therapies on the horizon include recombinant VWF, anti-VWF aptamers, and medications such as IL-11 to raise VWF levels. The key to effective treatment of VWD is an accurate diagnosis of the specific type and selection of hemostatic products appropriate for the clinical situation.

Alloantibodies in von Willebrand disease

The development of alloantibodies against von Willebrand factor (VWF) represents a rare but serious complication of treatment of von Willebrand disease (VWD), occurring in ~5% to 10% of type 3 VWD patients. Affected patients can present with a range of symptoms, including lack or loss of hemostatic response to infused VWF concentrates up to anaphylactic reactions in rare cases. It is classically reported in multitransfused patients and occurs most frequently in patients with partial or complete VWF gene deletions. A positive family history of anti-VWF antibodies also appears to be a risk factor. There is a lack of standardization of laboratory methods for antibody identification and characterization. Issues of variability in laboratory approaches as well as the rarity of the complication act as a barrier to future studies. Recombinant factor VIII as well as bypassing agents and immune tolerance have been reported as effective treatments; however, aside from case reports, little exists in the literature to guide management. The imminent clinical availability of recombinant VWF has prompted a resurgence of interest in this area. Additional study is warranted to address the deficiencies in our understanding of this treatment complication.