Hereditary angioedema: a decade of human C1-inhibitor concentrate therapy

The Lectin Pathway of the Complement System-Activation, Regulation, Disease Connections and Interplay with Other (Proteolytic) Systems

The complement system is the other major proteolytic cascade in the blood of vertebrates besides the coagulation-fibrinolytic system. Among the three main activation routes of complement, the lectin pathway (LP) has been discovered the latest, and it is still the subject of intense research. Mannose-binding lectin (MBL), other collectins, and ficolins are collectively termed as the pattern recognition molecules (PRMs) of the LP, and they are responsible for targeting LP activation to molecular patterns, e.g., on bacteria. MBL-associated serine proteases (MASPs) are the effectors, while MBL-associated proteins (MAps) have regulatory functions. Two serine protease components, MASP-1 and MASP-2, trigger the LP activation, while the third component, MASP-3, is involved in the function of the alternative pathway (AP) of complement. Besides their functions within the complement system, certain LP components have secondary ("moonlighting") functions, e.g., in embryonic development. They also contribute to blood coagulation, and some might have tumor suppressing roles. Uncontrolled complement activation can contribute to the progression of many diseases (e.g., stroke, kidney diseases, thrombotic complications, and COVID-19). In most cases, the lectin pathway has also been implicated. In this review, we summarize the history of the lectin pathway, introduce their components, describe its activation and regulation, its roles within the complement cascade, its connections to blood coagulation, and its direct cellular effects. Special emphasis is placed on disease connections and the non-canonical functions of LP components.

Efficacy of human C1 esterase inhibitor concentrate for treatment of ACE-inhibitor induced angioedema

BACKGROUND

ACE inhibitor (ACEi) induced angioedema predominantly affects the upper aerodigestive tract. As ACEi induced angioedema is mediated by bradykinin, therapeutic response to antihistamines and glucocorticoids remains unsatisfactory. In bradykinin mediated hereditary angioedema, C1-esterase inhibitor (C1INH) is an effective and approved treatment since many years. Our aim was to evaluate the therapeutic effect of C1INH in ACEi induced angioedema.

METHODS

We performed a double-blind, parallel-group, multicentre randomised placebo-controlled trial between December 2013 and September 2018. Eligible were adults with ACEi induced angioedema with airway obstruction. Participants were randomised 1:1 to single doses of either C1INH (20 IU/kg) or placebo (0.9% NaCl) i.v in addition to standard care (i.v. 500 mg prednisolone and 2.68 mg clemastine) i.v. Composite symptom scores were assessed at baseline and up to 48 h, at discharge and 1 week after discharge. Physician assessed time to complete oedema resolution (TCER) and time to onset of relief (TOR).

RESULTS

30 patients (16 C1INH, 14 placebo) were randomised and dosed. 25 (9 C1INH, 12 placebo) completed the study. TCER was 29.63 h ± 15.56 h in the C1INH and 17.29 h ± 10.40 h in the placebo arm (p = 0.0457). TORs were 4.13 h ± 3.38 h and 2.86 h ± 1.29 h for C1INH and placebo, respectively (p = 0.4443). There were no adverse events related to study medication.

CONCLUSIONS

In the context of baseline application of steroids and antihistamines C1INH was inferior in the treatment of ACEi induced angioedema when compared to placebo with respect to time to complete resolution of symptoms. Eudra-CT Number: 2012-001670-28.

Hereditary Angioedema in Pregnancy

Importance

Hereditary angioedema is a rare disease of potentially life-threatening attacks of angioedema that can affect patients of all ages, including women of childbearing age. Pregnancy can affect the course of the disease and the choice of treatment used. It is important for the care providers to recognize this disease and understand its mechanism in order to provide appropriate care for the patients.

Objective

The goal of this article is to provide an overview of hereditary angioedema and guideline for management of pregnant patients with hereditary angioedema.

Evidence Acquisition

A search of the available English language literature was performed on PubMed and Ovid MEDLINE using the key words hereditary angioedema and pregnancy. Additional articles were selected from the reference lists of the reviewed articles.

Results

The data for hereditary angioedema in pregnant patients come from observational studies, case reports, retrospective reviews, and questionnaires. The course of hereditary angioedema can be variable between different patients and pregnancies. Plasma-derived C1 inhibitor concentrate is both safe and effective as treatment for attacks and as preventive therapy in pregnancy. With proper recognition, understanding of the disease, and appropriate medical management, most patients will undergo successful pregnancy and delivery.

Conclusions and Relevance

Clinicians should maintain high suspicion for this disease when patients present with recurrent episodes of angioedema without urticaria or severe abdominal pains of unclear etiology. Treatment plans during pregnancy and delivery should be individualized, and the patient's care should be shared by a clinician experienced in the management of this disease.

Experience with Intravenous Plasma-Derived C1-Inhibitor in Pregnant Women with Hereditary Angioedema: A Systematic Literature Review

Consensus guidelines recommend plasma-derived C1 inhibitor (C1-INH) as first-line treatment in pregnant women with hereditary angioedema (HAE). We conducted a systematic review of the literature that describes experience with plasma-derived C1-INH during pregnancy. A literature search of PubMed was conducted in November 2018 using variants of "hereditary angioedema" and "pregnancy." English language articles that presented original data about the use of plasma-derived C1-INH during pregnancy were selected for data extraction. The search returned 253 unique records, of which 40 described the use of C1-INH during pregnancy (91 patients, 136 pregnancies). When the number of doses was reported, a total of 1562 doses were administered ranging from 500 to 3000 IU. Infusions were administered during all 3 trimesters and were most commonly administered during the third trimester. Overall, 1,490,500 IU of plasma-derived C1-INH were administered during pregnancy. Of the 128 fetuses for which outcomes were reported, 3 (2%) resulted in spontaneous abortion, 1 (1%) was stillborn, and 1 (1%) was a vanishing twin. Use of plasma-derived C1-INH in women with HAE during pregnancy has been widely reported in the scientific literature and has a favorable safety profile, supporting treatment guideline recommendations.

The International/Canadian Hereditary Angioedema Guideline

This is an update to the 2014 Canadian Hereditary Angioedema Guideline with an expanded scope to include the management of hereditary angioedema (HAE) patients worldwide. It is a collaboration of Canadian and international HAE experts and patient groups led by the Canadian Hereditary Angioedema Network. The objective of this guideline is to provide evidence-based recommendations, using the GRADE system, for the management of patients with HAE. This includes the treatment of attacks, short-term prophylaxis, long-term prophylaxis, and recommendations for self-administration, individualized therapy, quality of life, and comprehensive care. New to the 2019 version of this guideline are sections covering the diagnosis and recommended therapies for acute treatment in HAE patients with normal C1-INH, as well as sections on pregnant and paediatric patients, patient associations and an HAE registry. Hereditary angioedema results in random and often unpredictable attacks of painful swelling typically affecting the extremities, bowel mucosa, genitals, face and upper airway. Attacks are associated with significant functional impairment, decreased health-related quality of life, and mortality in the case of laryngeal attacks. Caring for patients with HAE can be challenging due to the complexity of this disease. The care of patients with HAE in Canada, as in many countries, continues to be neither optimal nor uniform. It lags behind some other countries where there are more organized models for HAE management, and greater availability of additional licensed therapeutic options. It is anticipated that providing this guideline to caregivers, policy makers, patients, and advocates will not only optimize the management of HAE, but also promote the importance of individualized care. The primary target users of this guideline are healthcare providers who are managing patients with HAE. Other healthcare providers who may use this guideline are emergency and intensive care physicians, primary care physicians, gastroenterologists, dentists, otolaryngologists, paediatricians, and gynaecologists who will encounter patients with HAE and need to be aware of this condition. Hospital administrators, insurers and policy makers may also find this guideline helpful.

Practicalities of a reduced volume formulation of a C1-INH concentrate for the treatment of hereditary angioedema: real-life experience

Background

Hereditary angioedema (HAE) due to C1 esterase inhibitor (C1-INH) deficiency is characterized by recurrent swelling attacks that can be life-threatening if left untreated. Prompt treatment is vital during acute attacks; plasma-derived C1-INH (Berinert^®) is one treatment currently licensed for the intravenous treatment of acute HAE attacks in adults, adolescents and children. A new, volume-reduced formulation, of C1-INH is currently available which aims to reduce the time to treatment, and provide greater convenience to patients and healthcare professionals. Here we compare the clinical experience of the reduced volume 1500 IU vial with multiple 500 IU vials.

Methods

HAE patients treated with C1-INH at the Royal London Hospital were selected to take part in this assessment. Included patients were aged 10–65 with moderate to severe HAE requiring high doses of C1-INH. The practicalities of the reduced 1500 IU vial compared with multiple 500 IU vials were assessed, including preparation and administration time, training to self-administer time and several quality of life aspects.

Results

Twenty-three patients participated in this study. Twenty-one patients were previously treated with C1-INH (Berinert^®) 500 IU for 1–14 years prior to switching to the 1500 IU vial format, two patients were naïve to C1-INH (Berinert^®). Preparation and administration of C1-INH (Berinert^®) 1500 IU was faster than an equivalent dose with multiple 500 IU vials (11 and 17 min, respectively) and also required less time to train to self-administer (45 and 55 min, respectively). Overall, patients rated the 1500 IU vial format higher in all assessed aspects than the 500 IU format, including preparation, administration, training, travel and storage. Nonetheless, reconstitution of the 1500 IU vial was noted more difficult, requiring gentle mixing to fully dissolve prior to intravenous injection. Patients remained stable on C1-INH (Berinert^®) 1500 IU; two patients switched back to multiple 500 IU vials due to headaches and preference for a larger volume.

Conclusions

The volume-reduced C1-INH concentrate (Berinert^®) 1500 IU is a practical and convenient alternative to multiple 500 IU vials for the treatment of HAE, which provides patients with more control and independence over their disease owing to a simpler to administer treatment.

Acquired and hereditary forms of recurrent angioedema: Update of treatment

The aim of treatment of hereditary angioedema (HAE) due to C1 esterase inhibitor deficiency (HAE-C1-INH) is either treating acute attacks or preventing attacks by using prophylactic treatment. For treating acute attacks, plasma-derived C1 inhibitor (C1-INH) concentrates, a bradykinin B2 receptor antagonist, and a recombinant human C1-INH are available in Europe. In the United States, a plasma-derived C1-INH concentrate, a bradykinin B2 receptor antagonist, and a plasma kallikrein inhibitor were approved for the treatment of acute attacks. Fresh frozen plasma is also available for treating acute attacks. Short-term prophylactic treatment focuses on C1-INH and attenuated androgens. Long-term prophylactic treatments include attenuated androgens such as danazol, stanozolol, and oxandrolone, antifibrinolytics, and a plasma-derived C1-INH concentrate. Plasma-derived C1-INH and a bradykinin B2 receptor antagonist are admitted for self-administration and home therapy. So the number of management options increased considerably within the last few years thus helping to diminish the burden of HAE.

Diagnosis and treatment of upper airway oedema caused by acute angio-oedema in the emergency department: a French consensus statement

Angio-oedema is a transitory, localized, noninflammatory oedema of subcutaneous tissue or mucous. When the oedema affects the mouth, lips, tongue or larynx, it can result in fatal asphyxiation in the absence of specific treatment. Oedema secondary to plasma extravasation is usually mediated by either histamine or bradykinin. As laboratory tests are not available in an emergency setting, the implicated mediator cannot be readily determined. The challenge for the emergency physician is to determine the aetiological type, evaluate severity and initiate adapted treatment by means of a structured approach. A team of experts from the French Reference Centre for Angio-oedema reached a consensus for recommendations for the diagnostic and therapeutic strategy to be adopted by emergency departments faced with angio-oedema of the upper airways in adults. The experts defined 11 important questions. Responses were rated using a two-round Delphi methodology. The 11 recommendations were related to triage on admission, a step-by-step diagnostic protocol, definition of attack severity, discouragement of instrumental examination, prioritization of treatment for severe attacks according to clinical signs and anticipation of access to specific treatments by the hospital. Angio-oedema of the upper airways can be fatal and requires anticipation by the emergency department. A search for the aetiology, an evaluation of clinical symptoms and the availability of the treatments are challenges justifying these recommendations.

Pharmacological Management of Hereditary Angioedema with C1-Inhibitor Deficiency in Pediatric Patients

Hereditary angioedema with C1-inhibitor deficiency (C1-INH-HAE) is a form of bradykinin-mediated angioedema. It is a rare disorder with an onset during childhood in most instances. Therefore, familiarity with the options for the management of pediatric cases is indispensable. The recurrent angioedematous episodes do not respond to conventional treatments and may evolve into a life-threatening condition. In view of the recommendations adopted by international consensus in 2016, patient management and follow-up should be guided by an individualized strategy. During the last decade, various medicinal products with novel modes of action and different posology have been developed for the treatment of C1-INH-HAE. These drugs either inhibit the release of bradykinin (plasma-derived C1-inhibitors, recombinant C1-inhibitors, kallikrein inhibitors) or prevent the released bradykinin from binding to its receptor (bradykinin B₂ receptor antagonists). This review summarizes the properties of the medicinal products currently available for the treatment of C1-INH-HAE, the indications for their use in pediatric patients, and the findings of the clinical trials conducted in this patient population. It is concluded by a brief outline of future therapeutic options.

Optimum Use of Acute Treatments for Hereditary Angioedema: Evidence-Based Expert Consensus

Acute treatment of hereditary angioedema due to C1 inhibitor deficiency has become available in the last 10 years and has greatly improved patients’ quality of life. Two plasma-derived C1 inhibitors (Berinert and Cinryze), a recombinant C1 inhibitor (Ruconest/Conestat alpha), a kallikrein inhibitor (Ecallantide), and a bradykinin B2 receptor inhibitor (Icatibant) are all effective. Durably good response is maintained over repeated treatments and several years. All currently available prophylactic agents are associated with breakthrough attacks, therefore an acute treatment plan is essential for every patient. Experience has shown that higher doses of C1 inhibitor than previously recommended may be desirable, although only recombinant C1 inhibitor has been subject to full dose–response evaluation. Treatment of early symptoms of an attack, with any licensed therapy, results in milder symptoms, more rapid resolution and shorter duration of attack, compared with later treatment. All therapies have been shown to be well-tolerated, with low risk of serious adverse events. Plasma-derived C1 inhibitors have a reassuring safety record regarding lack of transmission of virus or other infection. Thrombosis has been reported in association with plasma-derived C1 inhibitor in some case series. Ruconest was associated with anaphylaxis in a single rabbit-allergic volunteer, but no further anaphylaxis has been reported in those not allergic to rabbits despite, in a few cases, prior IgE sensitization to rabbit or milk protein. Icatibant is associated with high incidence of local reactions but not with systemic effects. Ecallantide may cause anaphylactoid reactions and is given under supervision. For children and pregnant women, plasma-derived C1 inhibitor has the best evidence of safety and currently remains first-line treatment.

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.

Investigational drugs in phase I and phase II clinical trials for hereditary angioedema

INTRODUCTION

Hereditary angioedema (HAE) with C1-inhibitor deficiency (C1-INH-HAE) is a rare bradykinin-mediated disease characterized by recurrent subcutaneous and/or submucosal angioedematous attacks (HAE attacks), which occur unpredictably. The recurrent HAE attacks do not respond to conventional treatments, and may evolve into a life-threatening condition; therefore, special therapy is required.

AREAS COVERED

The agents used so far for the acute management of HAE attacks act by blocking the release of bradykinin, or its binding to its receptor. By contrast, the investigational medicinal products under evaluation in Phase I and II clinical trials are targeted at the prevention of HAE attacks. Chemically, these new drugs are small synthetic molecules, oligonucleotides, or antibodies, which inhibit either kallikrein, or Factor XII.

EXPERT OPINION

The key considerations for the development of new medicinal products include more straightforward dosing, self-administration, longer duration of action, and keeping the patient attack-free. This review summarizes the status and the findings of the currently ongoing Phase I and Phase II clinical trials of C1-INH-HAE.

Use of a C1 Inhibitor Concentrate in Adults ≥65 Years of Age with Hereditary Angioedema: Findings from the International Berinert® (C1-INH) Registry

Background

Treatment of hereditary angioedema (HAE) in ‘older adults’ (those aged ≥65 years) has not been well studied. The international Berinert Patient Registry collected data on the use of intravenous plasma-derived, pasteurized, nanofiltered C1-inhibitor concentrate (pnfC1-INH; Berinert^®/CSL Behring) in patients of any age, including many older adults.

Methods

This observational registry, conducted from 2010 to 2014 at 30 US and seven European sites, gathered prospective (post-enrollment) and retrospective (pre-enrollment) usage and adverse event (AE) data on subjects treated with pnfC1-INH.

Results

The registry documented 1701 pnfC1-INH infusions in 27 older adults. A total of 1511 HAE attacks treated with pnfC1-INH administration were reported among 25 of the 27 (92.6 %) older adults. Among the older adults, mean (standard deviation [SD]) (8.8 [4.1] IU/kg) and median (6.4 IU/kg) pnfC1-INH doses were lower than those reported for 252 ‘younger adults’ (those aged <65 years: 12.9 [6.2], 12.5 IU/kg, respectively). A total of 19 AEs occurred in 8 of 23 (34.8 %) older adults with prospective data, for rates of 0.83 events per subject and 0.02 events per infusion, similar to corresponding rates in younger adults (0.91 and 0.03, respectively). None of the AEs were considered related to pnfC1-INH, and all but two events (prostatectomy, gastrointestinal bleeding) were mild or moderate in severity. Administration of pnfC1-INH outside of a healthcare setting was reported for 1609 infusions in 16 older adults, representing 94.6 % of all pnfC1-INH infusions in this age group. There were no recorded instances of difficulty with self-administration of intravenous pnfC1-INH.

Conclusions

These findings suggest a high degree of safety with intravenous pnfC1-INH use in older adults with HAE, regardless of administration setting.

Trial Registration Clinicaltrials.gov NCT01108848.

Pediatric Angioedema

PURPOSE OF REVIEW

The aims of this study are to update the clinician on current understanding of angioedema as it presents in the pediatric population and to review proper diagnostic techniques and treatment modalities for various types of angioedema.

RECENT FINDINGS

Angioedema is still best classified by whether it is likely histaminergic or kinin-mediated. New guidelines have been published around the world to help diagnose and treat both forms (urticaria/angioedema and hereditary angioedema). The vast majority of the studies on treatment have been conducted in the adult population; however, there are data available in the pediatric population. In the realm of hereditary angioedema, there are multiple new therapies that have been studied in the pediatric population (down to 2 years in some studies) in recent years and offer the clinician options for treatment. Angioedema (whether occurring with or without urticaria) is common in the pediatric population. The majority of the recent studies has been conducted in hereditary angioedema, and now, the clinician should have various options to treat all forms of angioedema. Many treatment options, especially for hereditary angioedema, are further being examined specifically in the pediatric population.

Efficacy and safety of an intravenous C1-inhibitor concentrate for long-term prophylaxis in hereditary angioedema

BACKGROUND

The plasma-derived, pasteurized, nanofiltered C1-inhibitor concentrate (pnfC1-INH) is approved in the United States as an intravenous (IV) on-demand treatment for hereditary angioedema (HAE) attacks, and, in Europe, as on demand and short-term prophylaxis.

OBJECTIVE

This analysis evaluated Berinert Patient Registry data regarding IV pnfC1-INH used as long-term prophylaxis (LTP).

METHODS

The international registry (2010-2014) collected prospective and retrospective usage, dosing, and safety data on individuals who used pnfC1-INH for any reason.

RESULTS

The registry included data on 47 subjects (80.9% female subjects; mean age, 44.8 years), which reflected 4082 infusions categorized as LTP and a total of 430.2 months of LTP administration. The median absolute dose of pnfC1-INH given for LTP was 1000 IU (range, 500-3000 IU), with a median time interval between infusion and a subsequent pnfC1-INH-treated attack of 72.0 hours (range, 0.0-166.4 hours). Fifteen subjects (31.9%) had no pnfC1-INH-treated HAE attacks within 7 days after pnfC1-INH infusion for LTP; 32 subjects (68.1%) experienced 246 attacks, with rates of 0.06 attacks per infusion and 0.57 attacks per month. A total of 81 adverse events were reported in 16 subjects (34.0%) (0.02 events per infusion; 0.19 events per month); only 3 adverse events were considered related to pnfC1-INH (noncardiac chest pain, postinfusion headache, deep vein thrombosis in a subject with an IV port).

CONCLUSION

In this international registry, IV pnf-C1-INH given as LTP for HAE was safe and efficacious, with a low rate of attacks that required pnfC1-INH treatment, particularly within the first several days after LTP administration.

Management of Children With Hereditary Angioedema Due to C1 Inhibitor Deficiency

Hereditary angioedema (HAE) is a potentially life-threatening inherited disease characterized by attacks of skin swelling, severe abdominal pain, and upper airway swelling. Attacks typically begin in childhood, but the appropriate diagnosis is often missed. Attacks do not respond to epinephrine, antihistamines, or glucocorticoids. Recently, many effective drugs have been approved for treatment of adults with HAE, and the Medical Advisory Board of the HAE Patient's Association has developed and reported treatment recommendations for adults. Only 1 medication is approved for treatment of children <12 years of age, and there are no reported consensus recommendations for treatment of young children in the United States. The 11-member Medical Advisory Board, with extensive experience in the treatment of children, in concert with the leaders of the HAE Patient's Association, has developed these consensus recommendations to help in recognition, diagnosis, treatment of attacks, and prophylaxis of children with HAE.

Assessment of inhibitory antibodies in patients with hereditary angioedema treated with plasma-derived C1 inhibitor

BACKGROUND

Limited data are available regarding C1 inhibitor (C1-INH) administration and anti-C1-INH antibodies.

OBJECTIVE

To assess the incidence of antibody formation during treatment with pasteurized, nanofiltered plasma-derived C1-INH (pnfC1-INH) in patients with hereditary angioedema with C1-INH deficiency (C1-INH-HAE) and the comparative efficacy of pnfC1-INH in patients with and without antibodies.

METHODS

In this multicenter, open-label study, patients with C1-INH-HAE (≥12 years of age) were given 20 IU/kg of pnfC1-INH per HAE attack that required treatment and followed up for 9 months. Blood samples were taken at baseline (day of first attack) and months 3, 6, and 9 and analyzed for inhibitory anti-C1-INH antibody (iC1-INH-Ab) and noninhibitory anti-C1-INH antibodies (niC1-INH-Abs).

RESULTS

The study included 46 patients (69.6% female; mean age, 38.9 years; all white) who received 221 on-site pnfC1-INH infusions; most patients received 6 or fewer infusions. No patient tested positive (titer ≥1:50) for iC1-INH-Ab at any time during the study. Thirteen patients (28.2%) had detectable niC1-INH-Abs in 1 or more samples. Nine patients (19.6%) had detectable niC1-INH-Abs at baseline; 3 of these had no detectable antibodies after baseline. Of 10 patients (21.7%) with 1 or more detectable result for niC1-INH-Abs after baseline, 6 had detectable niC1-INH-Abs at baseline. Mean times to symptom relief onset and complete symptom resolution per patient were similar for those with or without anti-niC1-INH-Abs.

CONCLUSION

Administration of pnfC1-INH was not associated with iC1-INH-Ab formation in this population. Noninhibitory antibodies were detected in some patients but fluctuated during the study independently of pnfC1-INH administration and appeared to have no effect on pnfC1-INH efficacy.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01467947.

Diagnostic and therapeutic management of hereditary angioedema due to C1-inhibitor deficiency: the Italian experience

PURPOSE OF REVIEW

Hereditary angioedema (HAE) due to C1-inhibitor (C1-INH) deficiency (C1-INH-HAE) is a rare disease, with a reported prevalence of about 1 : 50 000. C1-INH-HAE causes disabling symptoms, which may be life-threatening if swelling affects upper airways. Diagnostic procedures are now well established and the role of bradykinin as the main mediator of plasma outflow eliciting angioedema formation has been clearly elucidated.

RECENT FINDINGS

Increased understanding of the pathogenesis of C1-INH-HAE allowed in recent years the development of new drugs targeted to inhibit bradykinin synthesis (Ecallantide) or activity (Icatibant). At the same time, a recombinant C1-INH concentrate (Ruconest) was produced from the milk of transgenic rabbits and two plasma-derived C1-INHs (Berinert, Cinryze) underwent controlled trials to obtain marketing authorization. In 2012, an Italian network for C1-INH-HAE (ITACA) was established by physicians of 17 HAE reference centres to collect data from Italian patients and to homogenize and improve the diagnostic and therapeutic approach to the disease.

SUMMARY

Although there is a widespread agreement on therapeutic goals and treatment of C1-INH-HAE acute attacks, different approaches to prophylaxis are still present among HAE experts. The clinical experience of ITACA on a large population of C1-INH-HAE patients followed for several years may help in identifying the most effective strategies for the management of the disease.

Overview of Laboratory Testing and Clinical Presentations of Complement Deficiencies and Dysregulation

Historically, complement disorders have been attributed to immunodeficiency associated with severe or frequent infection. More recently, however, complement has been recognized for its role in inflammation, autoimmune disorders, and vision loss. This paradigm shift requires a fundamental change in how complement testing is performed and interpreted. Here, we provide an overview of the complement pathways and summarize recent literature related to hereditary and acquired angioedema, infectious diseases, autoimmunity, and age-related macular degeneration. The impact of complement dysregulation in atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria, and C3 glomerulopathies is also described. The advent of therapeutics such as eculizumab and other complement inhibitors has driven the need to more fully understand complement to facilitate diagnosis and monitoring. In this report, we review analytical methods and discuss challenges for the clinical laboratory in measuring this complex biochemical system.

Laboratory tests for disorders of complement and complement regulatory proteins

The complement pathway is a cascade of proteases that is involved in immune surveillance and innate immunity, as well as adaptive immunity. Dysfunction of the complement cascade may be mediated by aberrations in the pathways of activation, complement regulatory proteins, or complement deficiencies, and has been linked to a number of hematologic disorders, including paroxysmal noctural hemoglobinuria (PNH), hereditary angioedema (HAE), and atypical hemolytic-uremic syndrome (aHUS). Here, current laboratory tests for disorders of the complement pathway are reviewed, and their utility and limitations in hematologic disorders and systemic diseases are discussed. Current therapeutic advances targeting the complement pathway in treatment of complement-mediated hematologic disorders are also reviewed.

Plasma-derived C1-INH for managing hereditary angioedema in pediatric patients: A systematic review

Presently, medications approved for children with Hereditary Angioedema (HAE) are extremely limited. This is especially the case for children under 12 years of age. For this reason we reviewed and summarized the data on treatment of children with HAE. Available data indicate that plasma derived C1-inhibitor is a safe, effective treatment option for HAE in pediatric patients, including those below 12 years of age. Other therapies are also appear safe for the under 12 year of age, but less data are available. Importantly, home-based treatment of HAE in this age group appears to be safe and effective and can improve quality of life. These findings support current HAE consensus guidelines which strongly recommend the use of plasma derived C1-inhibitor as a first-line treatment in children and encourage home and self-treatment.

Efficacy of C1 esterase inhibitor concentrate in treatment of cutaneous attacks of hereditary angioedema

BACKGROUND

Although treatment with C1 esterase inhibitor (C1-INH) concentrate is well established for hereditary angioedema (HAE) attacks in general, data that assess its efficacy for cutaneous attack treatment are sparse.

OBJECTIVE

To assess efficacy of plasma-derived, nanofiltered C1-INH concentrate for cutaneous attack treatment by comparing treated attacks from the uncontrolled I.M.P.A.C.T.2 study with historical data for untreated attacks.

METHODS

Cutaneous attack data from patients with HAE who were treated for cutaneous edema with 20 IU/kg body weight C1-INH concentrate in the uncontrolled I.M.P.A.C.T.2 study (38 patients) were compared with data from untreated patients from an historical data base (46 patients) and included subset analyses for facial edema (treated group, 21 patients; untreated group, 33 patients) and peripheral edema (30 patients in each group). Average attack duration (AAD) per patient was the efficacy end point used to compare treated and untreated patients. Differences were assessed with a Wilcoxon test (primary analysis) and a log-rank test; AAD per patient was analyzed descriptively and graphically with Kaplan-Meier curves.

RESULTS

The AAD per patient of all cutaneous attacks or facial and peripheral cutaneous attack subsets was significantly faster with C1-INH treatment than without treatment (Wilcoxon and log-rank tests, both p < 0.0001 for all comparisons). Mean AADs per patient for all, facial, and peripheral attacks were 2.04, 1.45, and 2.16 days, respectively, in the C1-INH-treated group, and were 3.74, 4.45, and 2.98 days, respectively, in the untreated group. Kaplan-Meier curves corroborated the observed group differences.

CONCLUSION

Treatment of cutaneous HAE attacks (all attacks or facial and peripheral attack subsets) with 20 IU/kg C1-INH concentrate provided faster attack resolution compared with no treatment.

An evidence based therapeutic approach to hereditary and acquired angioedema

PURPOSE OF REVIEW

Hereditary angioedema (HAE) due to C1 esterase inhibitor (C1-INH) deficiency (HAE-C1-INH), HAE with normal C1-INH, and acquired angioedema due to C1-INH deficiency are rare but important diseases that can be associated with significant morbidity and mortality. Research into the pathogenesis of angioedema has expanded greatly and has led to new clinical trials with novel therapeutic agents and strategies.

RECENT FINDINGS

Strategies for managing HAE-C1-INH are aimed at treating acute attacks or preventing attacks through the use of prophylactic treatment. Agents available in Europe for treating acute attacks include plasma-derived C1-INH concentrates, a bradykinin B2 receptor (B2R) antagonist, and a recombinant human C1-INH. In the USA, a plasma-derived C1-INH concentrate, a bradykinin B2R antagonist, and a plasma kallikrein inhibitor have been approved for the treatment of acute HAE-C1-INH attacks. C1-INH concentrates and attenuated androgens are used for short-term prophylactic treatment. Long-term prophylactic treatments include attenuated androgens, a plasma-derived C1-INH concentrate, and antifibrinolytics. Plasma-derived C1-INH and a bradykinin B2R antagonist are approved for self-administration at home.

SUMMARY

The number of management options for HAE-C1-INH and similar conditions has increased considerably within the last few years, thus helping to alleviate the burden of these rare diseases.

Effect of C1-Esterase-inhibitor in angiotensin-converting enzyme inhibitor-induced angioedema

OBJECTIVES/HYPOTHESIS

The study objective was to generate pilot data to evaluate the effectiveness and safety of C1-esterase-inhibitor concentrate (C1-INH) compared to standard treatment in patients with angiotensin-converting enzyme inhibitor (ACEi)-induced angioedema affecting the upper aerodigestive tract.

STUDY DESIGN

Proof-of-concept case series with historical control.

METHODS

Adult patients with angioedema in the upper aerodigestive tract presenting to the emergency department were included. After establishing the diagnosis of ACEi-induced angioedema based on patient history and thorough clinical examination, all patients were administered 1,000 international units (IU) of C1-INH intravenously. A historical control group consisting of adult patients with ACEi-induced angioedema who had been treated with intravenous corticosteroids and antihistamines at the same institution over the past 8 years was used for comparison. The most important parameters assessed were the time to complete resolution of symptoms and the need for intubation or tracheotomy.

RESULTS

Ten patients were included in the C1-INH group and 47 in the corticosteroid/antihistamine group. The time to complete resolution of symptoms was considerably longer in the historical control group (33.1 ± 19.4 hours) than in the C1-INH group (10.1 ± 3.0 hours). No intubation or tracheotomy was needed in the C1-INH group (0/10 patients), whereas three out of the 47 historical controls required tracheotomy and two were intubated (5/47).

CONCLUSION

The results suggest a role for C1-INH as an effective and safe therapeutic option in patients with ACEi-induced angioedema, which needs to be confirmed by further larger and double-blinded studies.

LEVEL OF EVIDENCE

4.

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.

Managing Hereditary Angioedema Patients Undergoing Otolaryngeal Procedures

Background

Hereditary angioedema (HAE), a rare autosomal dominant disorder, is characterized by repeated attacks of swelling of the skin, gastrointestinal tract, face, larynx, and other organs. In most cases it is caused by low levels of functional C1 esterase inhibitor (C1-INH), a serine protease inhibitor that plays important regulatory roles in the complement, contact, and fibrinolytic pathways.

Methods

Lack of functional C1-INH results in excessive release of bradykinin, which triggers vasodilation, vascular permeability, and edema. Most attacks are mild and self-limiting, but untreated laryngeal attacks may cause rapid asphyxiation and death. Potential triggers of laryngeal attacks include trauma to or manipulation of the face, mouth, or upper airway. Therefore, before performing such a procedure in a patient with HAE, the otolaryngologist should consult with the patient, the physician managing the HAE, and the anesthesiologist and make appropriate preparations for prevention and/or treatment of an attack.

Results

Current World Allergy Organization and European guidelines recommend the use of i.v. plasma-derived C1-INH replacement for short-term prophylaxis of angioedema attacks. Other effective options include danazol given for several days before and after the procedure and fresh-frozen plasma, but these may not be as effective as C1-INH and may be associated with a high rate of adverse events.

Conclusion

Acute attacks, which may occur many hours after a procedure, may be treated with C1-INH; icatibant, a bradykinin B2-receptor antagonist; or ecallantide, a kallikrein inhibitor, all of which have been shown to reduce the duration and severity of HAE attacks.

Nanofiltered C1-esterase inhibitor for the acute management and prevention of hereditary angioedema attacks due to C1-inhibitor deficiency in children

OBJECTIVES

To evaluate the use of Cinryze (nanofiltered C1-esterase inhibitor [C1 INH-nf]) for the acute management and prevention of hereditary angioedema attacks in the subgroup of children and adolescents who participated in 2 placebo-controlled and 2 open-label extension studies.

STUDY DESIGN

In the acute-attack treatment studies, the efficacy of 1000 U of C1 INH-nf (with an additional 1000 U given 1 hour later if needed) was assessed based on the time to the start of symptomatic relief and the proportion of patients experiencing relief within 4 hours of therapy. In the prophylaxis studies, C1 INH-nf 1000 U was given twice weekly, and efficacy was based on the frequency of attacks.

RESULTS

Across 4 studies, 46 children received a total of 2237 C1 INH-nf infusions. The median time to the start of unequivocal relief in the acute-attack treatment study (n = 12) was 30 minutes with C1 INH-nf, compared with 2 hours for placebo. In the open-label extension (n = 22), clinical relief began within 4 hours of therapy in 89% of attacks. In the prophylaxis study (n = 4), the number of attacks was reduced by approximately 2-fold with C1 INH-nf compared with placebo. In the prophylaxis open-label extension (n = 23), the median monthly attack rate decreased from 3.0 before treatment to 0.39 with C1 INH-nf use.

CONCLUSION

In children, C1 INH-nf was well tolerated, provided relief from symptoms of hereditary angioedema attacks, and reduced the rate of attacks.

Current management options for hereditary angioedema

The aim of treatment of hereditary angioedema (HAE) due to C1 esterase inhibitor deficiency (HAE-C1-INH) is either treating acute attacks or preventing attacks by using prophylactic treatment. For treating acute attacks, plasma-derived C1 inhibitor (C1-INH) concentrates, a bradykinin B2 receptor antagonist, and a recombinant human C1-INH are available in Europe. In the United States, a plasma-derived C1-INH concentrate, a bradykinin B2 receptor antagonist, and a plasma kallikrein inhibitor have been approved. Fresh frozen plasma is also available for treating acute attacks. Short-term prophylactic treatment focuses on C1-INH and attenuated androgens. Long-term prophylactic treatments include attenuated androgens such as danazol, stanozolol, and oxandrolone, antifibrinolytics, and a plasma-derived C1-INH concentrate. Plasma-derived C1-INH and a bradykinin B2 receptor antagonist are permitted for self-administration and home therapy. The number of management options has increased considerably within the last few years, thus helping to diminish the burden of HAE.

Hereditary angioedema caused by c1-esterase inhibitor deficiency: a literature-based analysis and clinical commentary on prophylaxis treatment strategies

Hereditary angioedema (HAE) caused by C1-esterase inhibitor deficiency is an autosomal-dominant disease resulting from a mutation in the C1-inhibitor gene. HAE is characterized by recurrent attacks of intense, massive, localized subcutaneous edema involving the extremities, genitalia, face, or trunk, or submucosal edema of upper airway or bowels. These symptoms may be disabling, have a dramatic impact on quality of life, and can be life-threatening when affecting the upper airways. Because the manifestations and severity of HAE are highly variable and unpredictable, patients need individualized care to reduce the burden of HAE on daily life. Although effective therapy for the treatment of HAE attacks has been available in many countries for more than 30 years, until recently, there were no agents approved in the United States to treat HAE acutely. Therefore, prophylactic therapy is an integral part of HAE treatment in the United States and for selected patients worldwide. Routine long-term prophylaxis with either attenuated androgens or C1-esterase inhibitor has been shown to reduce the frequency and severity of HAE attacks. Therapy with attenuated androgens, a mainstay of treatment in the past, has been marked by concern about potential adverse effects. C1-esterase inhibitor works directly on the complement and contact plasma cascades to reduce bradykinin release, which is the primary pathologic mechanism in HAE. Different approaches to long-term prophylactic therapy can be used to successfully manage HAE when tailored to meet the needs of the individual patient.