Genetic test indications and interpretations in patients with hereditary angioedema

Summary and future of medicine for hereditary angioedema

Hereditary angioedema (HAE) is a rare autosomal genetic disease for which there are currently nine FDA-approved drugs. This review summarizes drug treatments for HAE based on four therapeutic pathways: inhibiting the contact system, inhibiting bradykinin binding to B2 receptors, supplying missing C1 inhibitors, and inhibiting plasminogen conversion. The review generalizes the clinical use, pharmacological effects and mechanisms of HAE drugs, and it also discusses possible development directions and targets to enhance understanding of HAE and help researchers.

Population pharmacokinetics of subcutaneous C1-inhibitor for prevention of attacks in patients with hereditary angioedema

BACKGROUND

Long-term prophylaxis with subcutaneous (SC) administration of a highly concentrated plasma-derived C1-esterase inhibitor (C1-INH) formulation was recently approved by the Food and Drug Administration for hereditary angioedema (HAE) attack prevention.

OBJECTIVE

To characterize the population pharmacokinetics of C1-INH (SC) (HAEGARDA^® ; CSL Behring) in healthy volunteers and HAE patients, and assess the variability and influence of covariates on pharmacokinetics.

METHODS

C1-INH functional activity data obtained after administration of various C1-INH (intravenous; IV) and C1-INH (SC) doses from 1 study in healthy volunteers (n = 16) and 2 studies in subjects with HAE (n = 108) were pooled to develop a population pharmacokinetic model (NONMEM v7.2). Pharmacokinetic parameters derived from steady-state simulations based on the final model were also evaluated.

RESULTS

C1-INH functional activity following C1-INH (SC) administration was described by a linear one-compartment model with first-order absorption and elimination, with inter-individual variability in all parameters tested. The mean population bioavailability of C1-INH (SC), and pharmacokinetic parameters for clearance (CL), volume of distribution, and absorption rate were estimated to be ~43%, 1.03 mL/hour/kg, 0.05 L/kg and 0.0146 hour^-1 , respectively. The effect of bodyweight on CL of C1-INH functional activity was included in the final model, estimated to be 0.74. Steady-state simulations of C1-INH functional activity vs time profiles in 1000 virtual HAE patients revealed higher minimum functional activity (C_trough ) levels after twice-weekly dosing with 40 IU/kg (~40%) and 60 IU/kg (~48%) compared with 1000 IU IV (~30%). Based on the population pharmacokinetic model, the median time to peak concentration was ~59 hours and the median apparent plasma half-life was ~69 hours.

CONCLUSIONS AND CLINICAL RELEVANCE

Twice-weekly bodyweight-adjusted dosing of C1-INH (SC) exhibits linear pharmacokinetics and dose-dependent increases in C_trough levels at each dosing interval. In this analysis, SC dosing led to maintenance of higher C_trough levels than IV dosing.

The international WAO/EAACI guideline for the management of hereditary angioedema-The 2017 revision and update

Hereditary Angioedema (HAE) is a rare and disabling disease. Early diagnosis and appropriate therapy are essential. This update and revision of the global guideline for HAE provides up-to-date consensus recommendations for the management of HAE. In the development of this update and revision of the guideline, an international expert panel reviewed the existing evidence and developed 20 recommendations that were discussed, finalized and consented during the guideline consensus conference in June 2016 in Vienna. The final version of this update and revision of the guideline incorporates the contributions of a board of expert reviewers and the endorsing societies. The goal of this guideline update and revision is to provide clinicians and their patients with guidance that will assist them in making rational decisions in the management of HAE with deficient C1-inhibitor (type 1) and HAE with dysfunctional C1-inhibitor (type 2). The key clinical questions covered by these recommendations are: (1) How should HAE-1/2 be defined and classified?, (2) How should HAE-1/2 be diagnosed?, (3) Should HAE-1/2 patients receive prophylactic and/or on-demand treatment and what treatment options should be used?, (4) Should HAE-1/2 management be different for special HAE-1/2 patient groups such as pregnant/lactating women or children?, and (5) Should HAE-1/2 management incorporate self-administration of therapies and patient support measures?

Brazilian Guidelines for Hereditary Angioedema Management - 2017 Update Part 1: Definition, Classification and Diagnosis

Hereditary angioedema is an autosomal dominant disease characterized by recurrent angioedema attacks with the involvement of multiple organs. The disease is unknown to many health professionals and is therefore underdiagnosed. Patients who are not adequately diagnosed and treated have an estimated mortality rate ranging from 25% to 40% due to asphyxiation by laryngeal angioedema. Intestinal angioedema is another important and incapacitating presentation that may be the main or only manifestation during an attack. In this article, a group of experts from the "Associação Brasileira de Alergia e Imunologia (ASBAI)" and the "Grupo de Estudos Brasileiro em Angioedema Hereditário (GEBRAEH)" has updated the Brazilian guidelines for the diagnosis and treatment of hereditary angioedema.

Management of hereditary angioedema in pregnant women: a review

THREE TYPES OF HEREDITARY ANGIOEDEMA (HAE) HAVE BEEN DESCRIBED

two are due to C1 inhibitor (C1-INH) deficiency (C1-INH-HAE types I and II) and one is characterized by normal C1-INH (nC1-INH-HAE). The management of pregnancy in patients with HAE is often a clinical challenge owing to potential worsening of the disease in relation to the physiological increase in estrogens and the limited treatment options. This review addresses the potential influence of pregnancy on the clinical severity of hereditary angioedema and the management of this disease during pregnancy with currently available treatments.

Biochemical comparison of four commercially available C1 esterase inhibitor concentrates for treatment of hereditary angioedema

Background

For safe and efficacious treatment of hereditary angioedema, C1 esterase inhibitor (C1-INH) concentrates should have high purity and high amounts of functional protein. As no pharmacopoeia requirements exist for C1-INH concentrate lot release, biochemical characteristics as declared by the manufacturers may not be compared directly. This study compared the characteristics and purity profiles of four commercially available C1-INH concentrates.

Study Design and Methods

The analysis included one transgenic (Ruconest) and three plasma-derived (Berinert, Cetor, Cinryze) C1-INH concentrates. C1-INH antigen concentration was determined by nephelometry, total protein (specific activity) with a Bradford assay, purity by size-exclusion chromatography and gel electrophoresis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was performed.

Results

Functionality (inversely proportional to antigen-to-activity ratio) was lowest for Ruconest (1.67), followed by Cetor (1.42), Berinert (1.24), and Cinryze (1.22). Specific activity (U/mg) and purity (%) were highest in Ruconest (12.13; 98.6) and Berinert (11.57; 97.0), followed by Cinryze (10.41; 89.5) and Cetor (9.01; 88.6). Main protein bands were found for all plasma-derived products at approximately 105 kDa, and for Ruconest, at approximately 98 kDa. Additional bands in the plasma-derived products were α1-antichymotrypsin, ceruloplasmin, Factor C3 (Cinryze/Cetor), and immunoglobulin heavy constant mu (Berinert).

Conclusion

Ruconest has a very high purity profile but is not identical to the human C1-INH protein. Of the plasma-derived products, Berinert has the highest purity profile. The impact of the nontherapeutic proteins identified has not yet been evaluated. For harmonization of the analysis for drug release, we recommend the establishment of regulatory requirements for purity determination and the implementation of threshold levels in C1-INH concentrates.

WAO Guideline for the Management of Hereditary Angioedema

Hereditary Angioedema (HAE) is a rare disease and for this reason proper diagnosis and appropriate therapy are often unknown or not available for physicians and other health care providers. For this reason we convened a group of specialists that focus upon HAE from around the world to develop not only a consensus on diagnosis and management of HAE, but to also provide evidence based grades, strength of evidence and classification for the consensus. Since both consensus and evidence grading were adhered to the document meets criteria as a guideline. The outcome of the guideline is to improve diagnosis and management of patients with HAE throughout the world and to help initiate uniform care and availability of therapies to all with the diagnosis no matter where the residence of the individual with HAE exists.

Hereditary and acquired complement component 1 esterase inhibitor deficiency: a review for the hematologist

Hereditary angioedema (HAE), a rare autosomal dominant disorder, was first described in the late 19th century. The disease remained poorly understood and without therapeutic options until the latter half of the 20th century. Advances in the understanding of immunologic and hematologic pathways have shed light on HAE, a disease characterized by painful and unpredictable recurrent attacks of nonpitting edema without urticaria. Recognition that a deficiency of complement component 1 (C1) esterase inhibitor leads to overproduction of vasoactive kinins that cause angioedema paved the way for the development of early treatments. Increased understanding of the role of bradykinin in hereditary and acquired forms of C1 esterase inhibitor deficiency has led to the development of more targeted treatments for this painful, debilitating and potentially life-threatening disease.

Recent developments in the treatment of acute abdominal and facial attacks of hereditary angioedema: focus on human C1 esterase inhibitor

Hereditary angioedema (HAE) is a potentially fatal genetic disorder typified by a deficiency (type I) or dysfunction (type II) of the C1-inhibitor (C1-INH) and characterized by swelling of the extremities, face, trunk, abdominal viscera, and upper airway. Type III is normal estrogen-sensitive C1-INH HAE. Bradykinin, the main mediator of HAE, binds to endothelial B2 receptors, increasing vascular permeability and resulting in edema. HAE management includes short- and long-term prophylaxis. For treating acute episodes, C1-INH concentrate is recommended with regression of symptoms achieved in 30-90 min. Infusions of 500-1000 U have been used in Europe for years. Two plasma-derived C1-INH concentrates have been licensed recently in the United States: Berinert(®) for treating acute attacks and Cinryze(®) for prophylaxis in adolescent/adult patients. A recombinant C1-INH that is being considered for approval (conestat alfa) exhibited significant superiority versus placebo. Ecallantide (Kalbitor(®)) is a selective kallikrein inhibitor recently licensed in the United States for treating acute attacks in patients aged >16 years. It is administered in three 10-mg subcutaneous injections with the risk of anaphylactic reactions. Icatibant (Firazyr(®)) is a bradykinin B2 receptor competitor. It is administered subcutaneously as a 30-mg injection and approved in Europe but not in the United States.

Two Cases of Recurrent Episodes of Angio Edema Without Urticaria or Pruritus

A 45 years old man reports recurrent episodes of marked lip and hand swelling; without urticaria or puritus occurring during surgical procedure for lymph nodes biopsy. He was diagnosed with lymphoma six months ago. He has had three episodes of severe, campy abdominal pain and bloating lasting up to 24–36 hours on the past year. No family history of Angioedema. Work up showed: CBC, chemistry and IgE were normal. C4 was 35 mg/dL (normal 50–100 mg/dl) C1 esterase inhibitor (C1 -INH) level: 18 mg/dL (normal 18–50 mg/dl), low C1 -INH function (less than 50% of normal) and low C1 q (less than 30% of normal)

Long-term prophylaxis of hereditary angioedema with androgen derivates: a critical appraisal and potential alternatives

Androgen derivatives are regarded as standard in the long-term prophylaxis of swelling attacks in patients with hereditary angioedema (HAE). Because of their relatively slow onset of action, they are not suitable for acute therapy. Long-term prophylaxis with androgen derivatives must be regarded critically, especially on account of their androgenic and anabolic effects, some of which are severe. The risk of adverse events increases with the daily dose and the duration of treatment. Thus, treatment always calls for close monitoring of patients with regard to potential adverse events. In addition, androgens are subject to numerous contraindications and they show interactions with a large number of other drugs. Off-label use, doping issues, clarification of reimbursement and the need to import the androgen derivatives, which are no longer marketed in Germany, result in additional effort for the treating physician in terms of logistics and time involved. In symptomatic treatment of acute attacks the intravenous substitution of C1-INH and - since 2008 - subcutaneous administration of icatibant are available. The two substances are well tolerated and their effect occurs rapidly and, when the diagnosis has been confirmed, reliably. In the light of these two treatment options for controlling acute attacks, prophylactic treatment of HAE patients with androgen derivatives such as danazol should be reassessed. Patients might benefit from a dose reduction or the withdrawal of androgen prophylaxis and attacks can be controlled with demand-oriented acute treatment using C1-INH or icatibant.

Hereditary angioedema: an update on available therapeutic options

There is no cure for hereditary angioedema (HAE). Therapeutic approaches consist of symptomatic therapy for acute attacks, short-term prophylaxis before surgery, and long-term prophylaxis for those with frequent and severe attacks. In Germany, C1-INH concentrate and icatibant are licensed for acute therapy. C1-INH concentrate, which is obtained from human plasma, is administered intravenously to restore the deficient C1-INH activity. This therapy, which has been available for decades, is effective and well-tolerated. Batch documentation is required by German law. The synthetic decapeptide icatibant is administered subcutaneously. It competes with bradykinin, the responsible inducer of edema formation, for binding to the bradykinin B2 receptor. Icatibant is also effective and well-tolerated, even on repeated administration. An additional human C1-inhibitor, a recombinant human C1-inhibitor and the recombinant inhibitor of kallikrein ecallantide are currently under development. There are no licensed treatment options available in Germany for long- and short-term prophylaxis. Androgen derivatives are established in long-term prophylaxis. However, they are associated with many adverse effects, some of which are severe. Many drug interactions also limit their use. They are contraindicated in pregnancy, lactation, for children and in cases of prostate cancer. Antifibrinolytics have fewer adverse effects but are also less effective than androgens. They are contraindicated in thromboembolic disease and impaired vision. If androgen therapy has too negative an effect on quality of life, it may be worth reducing the dose or discontinuing therapy entirely and treating attacks with acute therapy.

[Bradykinin mediated angioedema]

Bradykinin angioedema (AE) are characterized by acute recurrent episodes of localized swelling. They are not associated with pruritus or erythema, and are short-lived (24 to 72 hours), disappearing without any sequelae. Corticosteroids are useless. Skin or mucous membranes (upper respiratory and intestinal) could be affected. Bradykinin AE can be secondary to: (1) AE associated with C1 inhibitor deficiency (hereditary or acquired); (2) drug-induced AE (converting enzyme inhibitors…); (3) type III AE type (oestrogen dependant) without C1 inhibitor deficiency. These type III AE can be associated with a gain of function mutation that markedly increases factor XII activity. Prognosis depends on the laryngeal attacks (resulting in 25 % of death in the absence of specific treatment). In case of severe attacks, icatibant (bradykinin receptor antagonist) or C1 inhibitor concentrate can be used. In case of frequent attacks, long-term therapy with danazol or tranexamic acid is effective.

Hereditary angioedema: New therapeutic options for a potentially deadly disorder

Although the biochemistry of hereditary angioedema (HAE) is fairly well understood today, the lag in diagnosis of a decade or more suggests that clinicians have low awareness of this disease. This lag in diagnosis and hence treatment certainly stems from the rarity and complexity of the presentation which can be easily mistaken for allergic and non-allergic reactions alike. The symptoms of the disease include acute swelling of any or multiple parts of the body. The attacks may be frequent or rare, and they may vary substantially in severity, causing stomach discomfort or periorbital swelling in mild cases and hypovolemic shock due to abdominal fluid shift or asphyxiation in the most severe cases. Given that these patients are at significant risk for poor quality of life and death, greater awareness of this disease is needed to ensure that newly available, effective medications are used in these patients. These new medications represent significant advances in HAE therapy because they are targeted at the plasma cascades implicated in the pathophysiology of this disease. The clinical presentation of HAE, overlapping symptoms with other angioedemas, and available therapies are reviewed.

Hereditary angioedema: current and emerging treatment options

Angioedema can result from allergic, hereditary, and acquired conditions. Hereditary angioedema (HAE) attacks are disabling at the time of occurrence and can be life threatening; they often result in hospitalization and intensive care unit admission. Although there are several variants of HAE, they share a final common pathway: unopposed activation of multiple kinins and mediators including kallikrein and bradykinin. This leads to increased vascular permeability, which in turn produces the edema after which the condition is named. Older treatment options licensed in the United States, anabolic steroids and antifibrinolytics, have troublesome side effect profiles and may not reverse a severe acute attack. In Europe, C1 esterase inhibitor (C1-INH) concentrates have been used since 1974 for both preventing and terminating attacks. Two of these have now been licensed in the United States for use in HAE patients, one for prophylaxis and the other for treating acute abdominal and facial HAE attacks. The first kinin pathway modulator, ecallantide, has also been licensed recently in the United States for treating HAE attacks. The objective of this article is to describe HAE and review the available options for managing patients, as well as different drugs currently under investigation. Specific attention is given to the perioperative management of patients with HAE.

Angioedema beyond histamine: an educational case series

Angioedema constitutes an important clinical problem that can cause significant morbidity and mortality. Correct management requires a prompt recognition and treatment of the acute event and identification of the underlying cause. Many cases are caused by non-allergic reactions and do not result from mediator release by degranulating mast cells and basophils, but are related to accumulation of plasma and tissue bradykinin. This case series aims primarily to describe some important causes of non-allergic bradykinin-induced angioedema. Particular emphasis is put on clinical particularities, differential diagnosis, diagnostic approach and correct therapeutic management, as bradykinin-mediated angioedema is unresponsive to antihistamines.

Complement analysis in the 21st century

Complement analysis in the clinic is usually associated with the quantification of C3 and C4, measurement of C1-inhibitor and screening for complement activity. These analyses have been available in routine diagnostic laboratories for decades. In recent years, however, the field of complement analysis has expanded considerably, with the introduction of novel assays to detect complement activation products, and spreading still further towards genetic analysis to reveal the basis of complement deficiencies and identify mutations and polymorphisms associated with defined diseases such as atypical haemolytic uraemic syndrome and age related macular degeneration. Here we review the current status of complement analysis, including assays for the quantification of complement activity and complement activation products, together with genetic methods for the detection of deficiencies, mutations and polymorphisms. This is an area where significant developments have been made recently, paralleling the research advances into the role of complement in human disease. It is clear, however, that there is a need for consensus and standardisation of analytical methods. This will be a major challenge for the complement society in the future.

Gastrointestinal Involvement in a Case of Hereditary Angioedema: Could the Early Weaning Have Had a Role?

Hereditary angioedema (HAE) is a noninflammatory disorder due to reduced C1-inhibitor level and/or function and characterized by recurrent, circumscribed, and self-limiting episodes of cutaneous and mucous membrane swellings involving different organs. A heterogeneous group of mutations in the C1-inhibitor gene have been found. HAE might present with diverse clinical pictures, even within families with the same mutation, but the cause of this variability is not known yet. We describe the case of type II HAE in a young adult presenting with recurrent abdominal pain for many years, occasionally associated with ascites. We suppose that an early weaning might have influenced his phenotype, making his gastrointestinal tract a "vulnerable organ," in which hereditary angioedema could express itself.