Hereditary angioedema

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 angioedema treatment options: the availability of new therapies

Hereditary angioedema (HAE) is a potentially life-threatening autosomal dominant disease characterized by recurrent episodes of oedema, commonly occurring in the skin, abdomen, and upper respiratory tract. After many years during which limited treatment options were available, a range of newer therapies with proven efficacy have been approved in Europe by the European Commission for the treatment of HAE attacks. However, due to differing legislation and financial restrictions, these treatment options are not available in all countries. Home therapy and self-administration of treatment are recommended in order to minimize the burden of disease upon the patient, with the ideal treatment option being effective, well-tolerated, and easy to prepare and administer. Recently, the Hereditary Angioedema International Working Group (HAWK) consensus recommended early, on-demand treatment for HAE. This article reviews the current treatment options available, and considers the need for treatment guidelines to recommend the appropriate therapy.

Complement genetics, deficiencies, and disease associations

The complement system is a key component of innate immunity. More than 45 genes encoding the proteins of complement components or their isotypes and subunits, receptors, and regulators have been discovered. These genes are distributed throughout different chromosomes, with 19 genes comprising three significant complement gene clusters in the human genome. Genetic deficiency of any early component of the classical pathway (C1q, C1r/s, C2, C4, and C3) is associated with autoimmune diseases due to the failure of clearance of immune complexes (IC) and apoptotic materials, and the impairment of normal humoral response. Deficiencies of mannan-binding lectin (MBL) and the early components of the alternative (factor D, properdin) and terminal pathways (from C3 onward components: C5, C6, C7, C8, C9) increase susceptibility to infections and their recurrence. While the association of MBL deficiency with a number of autoimmune and infectious disorders has been well established, the effects of the deficiency of other lectin pathway components (ficolins, MASPs) have been less extensively investigated due to our incomplete knowledge of the genetic background of such deficiencies and the functional activity of those components. For complement regulators and receptors, the consequences of their genetic deficiency vary depending on their specific involvement in the regulatory or signalling steps within the complement cascade and beyond. This article reviews current knowledge and concepts about the genetic load of complement component deficiencies and their association with diseases. An integrative presentation of genetic data with the latest updates provides a background to further investigations of the disease association investigations of the complement system from the perspective of systems biology and systems genetics.

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.

New therapeutics in C1INH deficiency: a review of recent studies and advances

Hereditary angioedema (HAE) is a genetic condition causing a significant burden of illness for affected individuals. Episodes of angioedema involving the skin, gastrointestinal tract, as well as the larynx and oropharynx are often unpredictable and cause significant morbidity and mortality. Isolation of the underlying protein deficiency, specifically the serine protease C1 inhibitor, and further description of its role in multiple physiologic cascades has led to the development of several specific therapies for HAE. This report provides a brief overview of HAE but focuses primarily on reviewing recently published clinical studies of therapeutics developed for medical management of the condition.

Response time for ecallantide treatment of acute hereditary angioedema attacks

BACKGROUND

Hereditary angioedema (HAE) is a rare, debilitating, and potentially fatal disease characterized by acute attacks of swelling that can affect the abdomen/gastrointestinal tract, larynx, face, genitals, and extremities. Ecallantide is a novel plasma kallikrein inhibitor developed for the treatment of acute HAE attacks.

OBJECTIVE

To examine the speed of effect of ecallantide vs placebo.

METHODS

Data were integrated from 2 randomized, double-blind, placebo-controlled phase 3 trials of ecallantide in patients with HAE. Eligible patients presented within 8 hours of onset of a moderate to severe HAE attack for 1:1 randomization to receive a single dose of 30 mg of subcutaneous ecallantide or placebo. End points included time to beginning of improvement, time to sustained overall improvement, and time to significant overall improvement.

RESULTS

A total of 143 participants (70 receiving ecallantide and 73 receiving placebo) were included. The distribution curves for time to beginning of improvement demonstrated a trend in favor of ecallantide vs placebo within 4 hours (P(log rank) = .09). For time to onset of sustained improvement, the difference in the distribution of the curves between the 2 groups reached significance by 2 hours after dosing (P(log rank) = .04). For time to significant overall improvement, the difference in the distribution of the curves reached significance in favor of ecallantide by 90 minutes (P(log rank) = .04). The beneficial effect of ecallantide was demonstrated earliest for abdominal attacks, followed by laryngeal and peripheral attacks.

CONCLUSIONS

Ecallantide provides relief of acute HAE attack symptoms, with rapidity of response commensurate with therapeutic needs for HAE attack locations.

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.

Idiopathic systemic capillary leak syndrome (Clarkson's disease): the Mayo clinic experience

OBJECTIVE

To determine clinical features, natural history, and outcome of a well-defined cohort of 25 consecutive patients with idiopathic systemic capillary leak syndrome (SCLS) evaluated at a tertiary care center.

PATIENTS AND METHODS

Records of patients diagnosed as having SCLS from November 1, 1981, through April 30, 2008, were reviewed. Descriptive statistics were used to analyze patient demographics, clinical features, complications, and therapeutic interventions.

RESULTS

Of the 34 patients whose records were reviewed, 25 fulfilled all diagnostic criteria for SCLS. The median age at diagnosis of SCLS was 44 years. Median follow-up of surviving patients was 4.9 years, and median time to diagnosis from symptom onset was 1.1 years (interquartile range, 0.5-4.1 years). Flulike illness or myalgia was reported by 14 patients (56%) at onset of an acute attack of SCLS, and rhabdomyolysis developed in 9 patients (36%). Patients with a greater decrease in albumin level had a higher likelihood of developing rhabdomyolysis (p=.03). Monoclonal gammopathy, predominantly of the IgG-κ type, was found in 19 patients (76%). The progression rate to multiple myeloma was 0.7% per person-year of follow-up. The overall response rate to the different therapies was 76%, and 24% of patients sustained durable (>2 years) complete remission. The estimated 5-year overall survival rate was 76% (95% confidence interval, 59%-97%).

CONCLUSION

Systemic capillary leak syndrome, a rare disease that occurs in those of middle age, is usually diagnosed after a considerable delay from onset of symptoms. The degree of albumin decrement during an attack correlates with development of rhabdomyolysis. A reduction in the frequency and/or the severity of attacks was seen in nearly three-fourths of patients who were offered empirical therapies. The rate of progression to multiple myeloma appears to be comparable to that of monoclonal gammopathy of undetermined significance.

EDEMA4: a phase 3, double-blind study of subcutaneous ecallantide treatment for acute attacks of hereditary angioedema

BACKGROUND

Hereditary angioedema (HAE) is a genetic disorder resulting from low levels of C1-inhibitor activity that manifests as acute attacks of variable and sometimes life-threatening edema. Ecallantide is a novel potent inhibitor of human plasma kallikrein, a key mediator of the excessive formation of bradykinin associated with the signs and symptoms of an HAE attack.

OBJECTIVE

To evaluate the efficacy and safety of ecallantide in the treatment of acute HAE attacks.

METHODS

In this double-blind, placebo-controlled study, patients with a moderate to severe HAE attack were randomized 1:1 to receive 30 mg of subcutaneous ecallantide or placebo. The primary efficacy end point was change from baseline in mean symptom complex severity score 4 hours after dosing. Additional end points included treatment outcome score 4 hours after dosing and maintenance of significant overall improvement through 24 hours.

RESULTS

Ninety-six patients were enrolled. Mean (SD) change from baseline in mean symptom complex severity score 4 hours after dosing was significantly greater with ecallantide use (-0.8 [0.6]) compared with placebo use (-0.4 [0.8]) (P = .01 comparing distributions). Ecallantide therapy was also associated with a significantly larger mean (SD) treatment outcome score 4 hours after dosing vs placebo use (ecallantide: 53.4 [49.7]; placebo: 8.1 [63.2]; P = .003 comparing distributions). The benefit of ecallantide was apparent within 2 hours after dosing and was maintained through 24 hours after dosing. The safety profile was similar between the treatment groups.

CONCLUSION

Ecallantide appears to be an effective and safe treatment for acute attacks of HAE.

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.

Psychometric validation of two patient-reported outcome measures to assess symptom severity and changes in symptoms in hereditary angioedema

PURPOSE

Hereditary angioedema (HAE) is a rare disorder characterized by highly variable, acute attacks of swelling at various anatomical locations. Clinical measures do not adequately assess the diversity of symptoms characteristic of an attack. Two disease-specific, patient-reported outcome measures were developed to comprehensively capture symptom severity and change: the Treatment Outcome Score (TOS) and the Mean Symptom Complex Severity (MSCS) score.

METHODS

This study comprised a secondary analysis of pooled data from a randomized controlled trial to evaluate the psychometric properties, including reliability and validity, and minimally important difference (MID) of the TOS and MSCS score.

RESULTS

HAE patients (n = 73) had a mean age of 33 years, and 60% were female. Test-retest evaluation demonstrated moderate to substantial agreement (ICCs = 0.53 for TOS; 0.62 for MSCS score). The TOS and change in MSCS score were moderately to highly correlated with a Global Improvement Measure at 4 h (TOS: r = 0.90; MSCS: r = -0.59). Anchor- and distribution-based analyses suggested that conservative estimates for MID are 30 points for TOS and -0.30 points for 4-h change in MSCS score.

CONCLUSIONS

The psychometric tests performed here provide evidence of the reliability and validity of the TOS and MSCS for evaluating symptom severity and change in HAE patients. The TOS and MSCS score provide an example of measurement methodology that may be used to precisely capture symptom severity and change in a disease characterized by acute attacks.

Anti-cholesterol antibody levels in hereditary angioedema

Hereditary angioedema (HAE) is a rare disorder caused by the deficiency of the C1-inhibitor gene (C1INH) and characterized by recurrent bouts of angioedema. Autoimmune disorders frequently occur in HAE. Previously we found, that danazol has an adverse effect on serum lipid profile: reduced high-density lipoprotein (HDL) and elevated low-density lipoprotein (LDL) cholesterol levels are associated with long-term prophylactic use, whereas total cholesterol levels are unchanged. Our aim was to study the anti-cholesterol antibody (ACHA) production in HAE patients and compare it with those of healthy blood donors, and to investigate the possible associations between ACHA levels and serum lipid profile alterations caused by danazol. Anti-cholesterol IgG levels were measured by ELISA and their correlation with serum concentrations of total cholesterol, HDL, LDL, triglycerides was determined in HAE patients receiving/not receiving danazol. Serum ACHA levels were significantly higher in HAE patients, compared to healthy blood donors (P < 0.0001). Longterm danazol prophylaxis had no effect on serum ACHA levels in HAE patients. However, we found a significant, negative correlation between ACHA levels and serum total cholesterol (r =−0.4033, P = 0.0200), LDL (r =−0.4565, P = 0.0076) and triglyceride (r =−0.4230, P = 0.0121) levels only in danazol-treated patients, but not in HAE patients who did not receive long-term prophylaxis. Patients with HAE have higher baseline ACHA levels compared to healthy subjects, and this might reflect polyclonal B-cell activation. The latter would be a potential explanation for the lack of an increased incidence of infectious diseases in HAE patients, but might lead to increased autoimmunity.

Immunological mechanisms in the pathogenesis of diabetic retinopathy

There is an accumulating body of evidence that immunological mechanisms play a prominent role in the pathogenesis of diabetic retinopathy (DR), which is characterized by many features typical of inflammation. The upregulation of cytokines and other inflammatory mediators leading to persistent low-grade inflammation and an influx of leukocytes, is believed to contribute actively to DR-associated damage to the retinal vasculature and retinal neovascularization. This review will describe preclinical and clinical studies that document an inflammatory basis for DR and that support the use of nonsteroidal anti-inflammatory drugs, corticosteroids, and anti-vascular endothelial growth factor agents in its treatment. In addition, emerging therapeutic approaches based on ongoing investigations will be discussed, including those involving blockade of angiotensin receptors and other molecular targets such as tumor necrosis factor-alpha.

Pharmacological regulation of factor XII activation may be a new target to control pathological coagulation

FXII was identified 50 years ago as a coagulation protein in the intrinsic pathway of blood coagulation as FXII deficient patients had marked prolongation of the in vitro surface-activated coagulation time. However, series of investigations have convincingly shown that FXII has no role in normal hemostasis. Recently, experimentally induced thrombosis in factor XII-knockout mice has provided evidence that factor XII (FXII) deficient mice are protected against ischemic brain injury after obstructive clot formation. Based on these experiments it has, therefore, been suggested, that blocking of FXII could be a unique target to prevent obstructive clot formation in arterial thrombosis without side effect of increased bleeding. FXII deficiency has, however, not convincingly been shown to protect against arterial thrombosis in humans. The target mentioned above may either be an inhibition of FXII activation or an inhibition of its proteolytic activity. FXII is a zymogen of the proteolytic enzyme, FXIIa, the substrates of which are factor XI and prekallikrein. Thus, FXIIa is not only involved in the activation of the coagulation system, but is also associated with the kallikrein/kinin system. The activation of the latter is deeply involved in inflammation and pain sensation. Furthermore, FXIIa binds to endothelial cells and to the extracellular matrix, indicating a role in vascular repair. Therefore, a complete evaluation of all these properties of FXII and FXIIa has to be considered when formulating a strategy for blocking FXII activation.

Management of hereditary angioedema in pediatric patients

Hereditary angioneurotic edema is a rare disorder caused by the congenital deficiency of C1 inhibitor. Recurring angioedematous paroxysms that most commonly involve the subcutis (eg, extremities, face, trunk, and genitals) or the submucosa (eg, intestines and larynx) are the hallmarks of hereditary angioneurotic edema. Edema formation is related to reduction or dysfunction of C1 inhibitor, and conventional therapy with antihistamines and corticosteroids is ineffective. Manifestations occur during the initial 2 decades of life, but even today there is a long delay between the onset of initial symptoms and the diagnosis of hereditary angioneurotic edema. Although a variety of reviews have been published during the last 3 decades on the general management of hereditary angioneurotic edema, little has been published regarding management of pediatric hereditary angioneurotic edema. Thus, we review our experience and published data to provide an approach to hereditary angioneurotic edema in childhood.

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.

Idiopathic systemic capillary leak syndrome (SCLS): case report and systematic review of cases reported in the last 16 years

'Idiopathic systemic capillary leak syndrome (SCLS), or Clarkson's disease is an unusual entity first described 45 years ago. It presents with recurrent episodes of shock due to leakage of the plasma, which is reflected by accompanying hemo-concentration, hypo-albuminemia and edema. We report the case of a young man with multiple episodes of shock with generalized edema and pleural effusion. An initial diagnosis of sepsis was made, but the lack of fever and absence of a demonstrable organism or source led to a revision of diagnosis to SLCS. The last review of this syndrome which analyzed 24 cases was published in 1990. Since then, 75 more cases have been reported. This article reviews these cases.