Prospective study of rapid relief provided by C1 esterase inhibitor in emergency treatment of acute laryngeal attacks in hereditary angioedema

Edema of the Scrotum and Penile Shaft: An Uncommon Initial Presentation of Acquired Angioedema With Low C1-Inhibitor

Acquired angioedema with low C1-inhibitor (AAE-C1-INH) is a rare disorder characterized by an acquired deficiency in the C1 esterase inhibitor (C1-INH). This case report describes a 79-year-old patient presenting to the emergency department for painless swelling of his scrotum, penile shaft, and left lower and upper extremities with lab values consistent with acquired angioedema without identifiable lymphoreticular or rheumatic disorder on history, exam, or total body PET scan. Proper diagnosis of AAE-C1-INH is essential to prevent life-threatening airway compromise, ensure proper therapy, and exclude lymphoreticular disorders as the etiology of AAE-C1-INH.

Plasma-derived C1 esterase inhibitor pharmacokinetics and safety in patients with hereditary angioedema

Background

Over 40 years of use demonstrates that complement 1 esterase inhibitor (C1-INH) concentrate is effective and well tolerated for acute edema attacks and prophylaxis in patients with hereditary angioedema. OCTA-C1-INH is a new stable, virus-inactivated, nanofiltrated concentrate of C1-INH derived from human plasma.

Objective

We investigated the pharmacokinetics and safety profile of new C1-INH in people with hereditary angioedema during an attack-free period.

Methods

In this prospective, multicenter, open-label, single-arm study, adults with hereditary angioedema type I/II received a single intravenous dose of 20 IU/kg C1-INH. Blood samples were taken ≤30 minutes before infusion, and 0, 0.25, 1, 2, 6, 12, 24, 48, 72, 120, 144, and 168 hours after infusion. The primary end point was assessing the pharmacokinetic parameters of C1-INH measured by C1-INH activity. Safety end points were also examined.

Results

Twenty patients received a single dose of 20 IU/kg new C1-INH with a mean (standard deviation) total dose of 1457.3 (356.51) IU. Mean (standard deviation) area under the curve normalized by dose was 51.6 (17.9) h∙IU/mL/IU, maximum blood concentration was 1.14 (0.989) IU/mL, incremental recovery was 0.0466 (0.051) (IU∙kg)/(IU∙mL), half-life was 0.598 (0.716) hours, and time to maximum concentration was 0.598 (0.716) hours. No thromboembolic events were recorded. No treatment-emergent adverse events were rated as severe/serious.

Conclusion

PK parameters of new C1-INH were in line with those reported for other C1-INH concentrates. New C1-INH demonstrated a favorable safety profile in patients with C1-INH deficiency. Further studies are warranted to determine the effectiveness and longer-term safety of new C1-INH.

Bradykinin-induced angioedema in the emergency department

Background

Acute airway angioedema commonly occurs through two distinct mechanisms: histamine- and bradykinin-dependent. Although they respond to distinct treatments, these two potentially life-threatening states present similarly. Poor recognition of the bradykinin-dependent pathway leads to treatment errors in the emergency department (ED), despite the availability of multiple pharmacologic options for hereditary angioedema (HAE) and other forms of bradykinin-induced angioedema. Here, we consider the pathophysiology and clinical features of bradykinin-induced angioedema, and we present a systematic literature review exploring the effectiveness of the available therapies for managing such cases.

Methods

PubMed searches using ‘emergency’, ‘bradykinin’ and various therapeutic product names identified studies reporting the efficacy of treatments for bradykinin-induced angioedema in the ED setting. In all, 22 studies met prespecified criteria and are analysed here.

Findings

Whereas histamine-induced angioedema has a faster onset and often presents with urticaria, bradykinin-induced angioedema is slower in onset, with greater incidence of abdominal symptoms. Acute airway angioedema in the ED should initially be treated with anaphylactic protocols, focusing on airway management and treatment with epinephrine, antihistamine and systemic steroids. Bradykinin-induced angioedema should be considered if this standard treatment is not effective, despite proper dosing and regard of beta-adrenergic blockade. Therapeutics currently approved for HAE appear as promising options for this and other forms of bradykinin-induced angioedema encountered in the ED.

Conclusion

Diagnostic algorithms of bradykinin-induced angioedema should be followed in the ED, with early use of approved therapies to improve patient outcomes.

The international WAO/EAACI guideline for the management of hereditary angioedema - The 2021 revision and update

Hereditary Angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1-inhibitor (type 1) and HAE with dysfunctional C1-inhibitor (type 2), by providing guidance on common and important clinical issues, such as: 1) How should HAE be diagnosed? 2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? 3) What are the goals of treatment? 4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast feeding women? 5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

The international WAO/EAACI guideline for the management of hereditary angioedema-The 2021 revision and update

Hereditary angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1 inhibitor (type 1) and HAE with dysfunctional C1 inhibitor (type 2), by providing guidance on common and important clinical issues, such as: (1) How should HAE be diagnosed? (2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? (3) What are the goals of treatment? (4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast-feeding women? and (5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

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?

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.

Drug-Induced Inhibition of Angiotensin Converting Enzyme and Dipeptidyl Peptidase 4 Results in Nearly Therapy Resistant Bradykinin Induced Angioedema: A Case Report

BACKGROUND Bradykinin is an underestimated mediator of angioedema. One subgroup of bradykinin induced angioedema is angioedema triggered by treatment with angiotensin converting enzyme (ACE) inhibitors. Due to its localization in the head and neck region and its unpredictable course, it is a possibly life-threatening condition. There is not an officially approved treatment for ACE inhibitor induced angioedema. CASE REPORT We present a case of an 83-year-old woman, who presented to our ENT department because of acute swelling of the tongue. On admission, there was no pharyngeal or laryngeal edema and no dyspnea. Treatment with glucocorticoids and antihistamines had no response. The patient had ramipril as regular medication, so we assumed ACE inhibitor induced angioedema and treated consequently with C1-inhibitor (human) 1,500 IU. Nevertheless, swelling was progressive and required intubation. Even after the second specific treatment with icatibant, her angioedema subsided extremely slowly. The patient also had regular treatment with saxagliptin, a dipeptidyl peptidase 4 inhibitor, so we assumed that the simultaneous inhibition of two bradykinin degrading enzymes led to a treatment-refractory course of angioedema. CONCLUSIONS General awareness for bradykinin induced angioedema due to regular medication is limited. Our case demonstrated the importance of improving awareness and knowledge about this side effect. We need a better understanding of the pathomechanism to aid in more precise clinical diagnosis. Securing the patient's airway as well as administration of an officially approved therapy is of utmost importance. As the number of patients simultaneously treated with antihypertensive and antidiabetic drugs is likely to increase, the incidence of bradykinin mediated drug induced angioedema is likely to increase as well.

Patient Characteristics and Individualization of Biologic Therapy

Progress in the understanding of disease processes has provided additional therapeutic targets, best exemplified by the increasing role of biologics in the clinical armamentarium. This article provides a focused review of current treatment paradigms and pathophysiology for asthma, atopic dermatitis, urticaria, as well as C1 inhibitor deficiency. It elucidates the populations in which biologics were studied for the aforementioned disease states, emphasizing characteristics to consider when selecting therapy. It is important to correctly estimate patient outcome before starting therapy based on cost analysis. Treatment decisions need to be guided by appropriate patient stratification based on each individual's underlying phenotype.

Efficacy of Different Medical Therapies for the Treatment of Acute Laryngeal Attacks of Hereditary Angioedema due to C1-esterase Inhibitor Deficiency

BACKGROUND

Hereditary angioedema (HAE) is a rare disease characterized by C1-esterase inhibitor (C1-INH) deficiency, resulting in periodic attacks of acute edema, which can be life-threatening if they occur in the upper airway. No head-to-head comparisons of different treatment options for acute HAE attacks are available. Because immediate symptom relief is critical for potentially life-threatening laryngeal attacks, it is important to determine the treatment option that provides optimal treatment response.

OBJECTIVE

Review and compare data from clinical studies that evaluated the efficacy and safety of treatments for laryngeal HAE attacks.

METHODS

We conducted an indirect comparison of clinical outcomes from prospective studies for treatment of 881 acute laryngeal attacks with plasma-derived C1-INH concentrate (pdC1-INH) at fixed doses (500 or 1000 U) or a body weight-adjusted dose (20 U/kg), recombinant C1-INH concentrate at a fixed dose (2100 U), or a body weight-adjusted dose (50 U/kg), icatibant (30 mg), or ecallantide (30 mg). Comparisons included time to onset of symptom relief and need for re-dosing or emergency procedures.

RESULTS

The median time to onset of symptom relief ranged between 15 min and approximately 2 h, and was shortest with body weight-adjusted doses of pdC1-INH. The proportion of laryngeal attacks with re-dosing ranged between 0% and 72%. No re-dosing was needed after treatment with a single body weight-adjusted dose of pdC1-INH (48 attacks).

CONCLUSIONS

Available data suggest that among different HAE treatments, body weight-adjusted pdC1-INH (20 U/kg) provides the most reliable treatment response for treatment of laryngeal HAE attacks.

Safety and efficacy of C1 esterase inhibitor for acute attacks in children with hereditary angioedema

BACKGROUND

Human plasma-derived nanofiltered C1 esterase inhibitor (C1 INH-nf) is used to treat acute angioedema attacks in patients with hereditary angioedema (HAE), but data regarding use in children are sparse.

METHODS

Patients 2 to <12 years of age, body weight ≥10 kg, with a diagnosis of HAE type I or II, were recruited for a multicenter open-label trial. Patients were recruited into 2 weight categories (10-25 kg, >25 kg). Each weight category included 2 dosing levels: C1 INH-nf (500 units [U], 1000 U) and C1 INH-nf (1000 U, 1500 U), respectively. Patients experiencing an angioedema attack were given a single intravenous dose. Primary efficacy end-point was the onset of unequivocal relief of the defining symptom within 4 h following initiation of C1 INH-nf treatment.

RESULTS

Nine children were treated: 3 (10-25 kg) received 500 U; 3 (>25 kg) received 1000 U; and 3 (>25 kg) received 1500 U. The lower weight/higher dose category (10-25 kg, 1000 U) was not successfully enrolled. All patients completed the study. Most angioedema attacks (n = 5) were abdominal. All patients met the primary end-point; median time to unequivocal symptom relief was 0.5 (range: 0.25-2.5) h. Doses of C1 INH-nf ranged from 20.8 to 51.9 U/kg.

CONCLUSIONS

Treatment of a single angioedema attack with C1 INH-nf doses of 500 U (in patients 10-25 kg), 1000 U, and 1500 U (in patients >25 kg) were well tolerated. Doses of C1 INH-nf <1000 U may be appropriate in some pediatric patients.

Cardiac arrest due to airway obstruction in hereditary angioedema

Hereditary angioedema (HAE) is a rare genetic disease caused by a deficiency of functional C1 esterase inhibitor that causes swelling attacks in various body tissues. We hereby report a case of out-of-hospital cardiac arrest due to airway obstruction in HAE. Cutaneous swelling and abdominal pain attacks caused by gastrointestinal wall swelling are common symptoms in HAE, whereas laryngeal swelling is rare. Emergency physicians may have few chances to experience cases of life-threatening laryngeal edema resulting in a delay from symptom onset to the diagnosis of HAE. Hereditary angioedema is diagnosed by performing complement blood tests. Because safe and effective treatment options are available for the life-threatening swellings in HAE, the diagnosis potentially reduces the risk of asphyxiation in patients and their blood relatives.

Hereditary angioedema: a brief review of new developments

BACKGROUND

Angioedema is a serious medical condition characterized by recurrent non-pitting tissue edema. Hereditary (HAE) forms of this disorder are potentially fatal.

METHODS

PubMED, Up to Date and Cochrane Library databases were used to identify scholarly peer reviewed original research or review articles on angioedema. Search terms used were: angioedema, HAE, ACE inhibitor induced angioedema, acquired angioedema, type III HAE (now termed HAE with normal C1-INH), diagnosis of HAE, and treatment of HAE. Inclusive dates of the search were 1946 through 2013. Articles on urticaria were excluded.

RESULTS

The pathophysiology, clinical manifestations, differential diagnosis and treatments of angioedema are presented. Three variants of HAE are discussed and differentiated from acquired, ACE induced and allergic types of angioedema. Emphasis is placed on understanding that HAE is mediated by bradykinin, not histamine, and is therefore unresponsive to antihistamines, corticosteroids and epinephrine. In contrast, newer therapies that replace C1-INH or block bradykinin production or action are the appropriate treatments for prophylaxis and acute treatment of HAE.

CONCLUSION

Recognition of HAE by primary care providers and distinguishing it from allergic histamine mediated angioedema is essential in preventing recurrent attacks and avoiding inappropriate therapy, and may be life-saving.

Open-label, multicenter study of self-administered icatibant for attacks of hereditary angioedema

BACKGROUND

Historically, treatment for hereditary angioedema (HAE) attacks has been administered by healthcare professionals (HCPs). Patient self-administration could reduce delays between symptom onset and treatment, and attack burden. The primary objective was to assess the safety of self-administered icatibant in patients with HAE type I or II. Secondary objectives included patient convenience and clinical efficacy of self-administration.

METHODS

In this phase IIIb, open-label, multicenter study, adult patients were trained to self-administer a single 30-mg icatibant subcutaneous injection to treat their next attack. Icatibant-naïve patients were treated by an HCP prior to self-administration. Evaluations included adverse event (AE) reporting, a validated questionnaire for convenience, and visual analog scale for efficacy.

RESULTS

A total of 151 patients were enrolled; 104 had an attack requiring treatment during the study, and 97 patients (19 naïve) were included in the self-administration cohort. Recurrence or worsening of HAE symptoms (22 of 97) was the most commonly reported AE; rescue medications including icatibant (N = 3) and C1-inhibitor concentrate (N = 6) were used in 13 cases. Overall, 89 of 97 patients used a single injection of icatibant. No serious AEs or hospitalizations were reported. Most patients (91.7%) found self-administration preferable to administration in the clinic. The median time to symptom relief (3.8 h) was comparable with results from controlled trials of icatibant.

CONCLUSIONS

With appropriate training, patients were successfully able to recognize HAE attacks and decide when to self-administer icatibant. This, coupled with the patient-reported high degree of satisfaction, convenience and ease of use supports the adoption of icatibant self-administration in clinical practice.

Pharmacokinetics of plasma-derived C1-esterase inhibitor after subcutaneous versus intravenous administration in subjects with mild or moderate hereditary angioedema: the PASSION study

Background

Hereditary angioedema (HAE) is a rare disease caused by C1-esterase inhibitor (C1-INH) deficiency, characterized by periodic attacks of acute edema affecting subcutaneous (SC) tissues and mucous membranes. Human C1-INH concentrate given intravenously (IV) is effective and safe, but venous access may be difficult. We compared SC and IV administration of human pasteurized C1-INH concentrate with respect to pharmacokinetics, pharmacodynamics, and safety.

Study Design and Methods

This was a prospective, randomized, open-label, crossover study. Twenty-four subjects with mild or moderate HAE were randomly assigned during an attack-free interval to receive 1000 units of human pasteurized C1-INH concentrate IV or SC. Plasma levels of C1-INH activity and antigen, C4 antigen, cleaved high-molecular-weight kininogen (clHK), and C1-INH antibodies were measured.

Results

The mean relative bioavailability of functional C1-INH after SC administration was 39.7%. Maximum C1-INH activity after SC administration occurred within 48 hours and persisted longer than after IV administration. C4 antigen levels increased and clHK levels decreased after IV and SC administration, indicating the pharmacodynamic action of C1-INH. The mean half-life of functional C1-INH was 62 hours after IV administration and 120 hours after SC administration (p = 0.0595). C1-INH concentrate was safe and well tolerated when administered via both routes. As expected, SC administration resulted in a higher incidence of injection site reactions, all of which were mild.

Conclusion

With a relative bioavailability of 39.7%, SC administration of human pasteurized C1-INH yields potentially clinically relevant and sustained plasma levels of C1-INH and is safe and well tolerated.

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.

C1 inhibitor concentrate treatment of multiple laryngeal attacks in a 53-year-old woman with hereditary angioedema

This report describes a woman who experienced a high number of laryngeal hereditary angioedema (HAE) attacks during her participation in the IMPACT2 clinical trial of C1-INH concentrate. A 53-year-old caucasian female with a 31-year history of type 1 HAE experienced 16 laryngeal HAE attacks between 3 August 2006 and 23 February 2010, 15 of which were severe. All laryngeal attacks were successfully treated with C1-INH 20 U/kg, with a median onset of relief of 14 min and median time to complete resolution of symptoms of 20 h, and no need for redosing. The reliable success of C1-INH for these potentially fatal events is reassuring for both patients and prescribers.

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.

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.

C1-INH concentrate for treatment of acute hereditary angioedema: a pediatric cohort from the I.M.P.A.C.T. studies

BACKGROUND

We analyzed the clinical response of pediatric and adolescent hereditary angioedema (HAE) patients to pdC1-INH in the International Multicenter Prospective Angioedema C1-INH Trials (I.M.P.A.C.T.) 1 and 2.

METHODS

Patients included in this post hoc analysis of prospectively collected data were between 10 and 18 yr old with type I or II HAE and a documented history of abdominal or facial attacks. Patients received a single injection of pdC1-INH concentrate (Berinert(®) , CSL Behring, Marburg, Germany) 20 U/kg. Efficacy end-points were time from the administration of study drug to onset of symptom relief and time to complete relief of all symptoms.

RESULTS

Seven pediatric patients were included in I.M.P.A.C.T.1 with only 1 attack analyzed per patient. Median time to onset of relief was 0.42 h and to complete resolution was 8.08 h. No patient experienced a worsening of symptoms during the 0-4-h assessment period. Nine patients who experienced a total of 115 attacks were included in the analysis of I.M.P.A.C.T.2. Abdominal attacks were rated as 'severe' more frequently than were other types of attacks. The number of attacks per patient ranged from 2 to 42, and study participation ranged from 1 to 38 months. Median times to onset of symptom relief and to complete symptom resolution were 0.49 h and 14.1 h, respectively. Of 4 treatment-emergent adverse events in both studies, only 2 were considered related to treatment.

CONCLUSIONS

Study results showed that outcomes with pdC1-INH treatment of HAE in pediatric patients are comparable with outcomes in adults.

Outcomes after ecallantide treatment of laryngeal hereditary angioedema attacks

BACKGROUND

Hereditary angioedema (HAE) is a rare disorder associated with episodic attacks of well-demarcated angioedema. Attacks that affect the larynx can result in life-threatening airway obstruction.

OBJECTIVES

To examine efficacy and safety of ecallantide treatment for laryngeal HAE attacks.

METHODS

Data were combined from 4 clinical studies (EDEMA2, EDEMA3, EDEMA4, and DX-88/19) evaluating 30 mg of subcutaneous ecallantide for treatment of acute HAE attacks. Efficacy was assessed using 2 validated, HAE-specific, patient-reported outcome measures. The change in Mean Symptom Complex Severity (MSCS) score indicates change in symptom severity; a negative score indicates improvement. The calculated minimally important difference (MID) for change in severity is -0.30. The Treatment Outcome Score (TOS) measures treatment response. A positive score indicates improvement; the calculated MID is 30.

RESULTS

Overall, 98 patients received ecallantide for 220 laryngeal attacks. The mean ± SD change in MSCS score was -1.1 ± 0.73 and -1.6 ± 0.68 at 4 and 24 hours, respectively. The mean ± SD TOS was 73.5 ± 35.8 and 85.5 ± 27.8 at 4 and 24 hours, respectively. Median time to significant improvement was 185 minutes (95% confidence interval, 167-226). One attack required intubation. Four treatment-emergent serious adverse events were reported, including 2 HAE attacks that resulted in hospitalization and 2 anaphylactic reactions. One of these reactions required treatment with epinephrine, but both patients recovered fully. There were no deaths.

CONCLUSION

In this large attack series, ecallantide was effective for treatment of laryngeal HAE attacks. There is a risk of hypersensitivity, including anaphylaxis, consistent with product labeling. As such, ecallantide should be administered under the supervision of a health care professional.

TRIAL REGISTRATION

clinicaltrials.gov Identifiers: not applicable for EDEMA2 (trial was conducted before implementation of registration requirements); NCT00262080 for EDEMA3, NCT00457015 for EDEMA4, and NCT00456508 for DX-88/19.

Fatal laryngeal attacks and mortality in hereditary angioedema due to C1-INH deficiency

BACKGROUND

Hereditary angioedema due to C1 inhibitor deficiency (HAE-C1-INH) is characterized by relapsing skin swellings, abdominal pain attacks, and, less frequently, potentially life-threatening laryngeal attacks.

OBJECTIVE

This study determined the mortality of patients with and without the diagnosis of HAE-C1-INH and analyzed fatal laryngeal attacks.

METHODS

A cohort of 728 patients from 182 families with HAE-C1-INH was evaluated for death cases by analyzing pedigrees. Detailed information on fatal laryngeal attacks in 36 patients was obtained by questioning relatives and treating physicians.

RESULTS

Of the 214 patients who had died, 70 asphyxiated during a laryngeal attack. Mortality by asphyxiation was higher in patients with undiagnosed HAE-C1-INH (63 cases) than in patients with diagnosed HAE-C1-INH (7 cases). The lifespan of asphyxiated patients with undiagnosed HAE-C1-INH was on average ∼31 years shorter than patients with undiagnosed HAE-C1-INH who died of other causes. Three phases were distinguished in the fatal laryngeal attacks. Phase 1, the predyspnea phase, lasted on average for 3.7 ± 3.2 hours (range, 0-11 hours). Phase 2, the dyspnea phase, lasted on average for 41 ± 49 minutes (range, 2 minutes to 4 hours). Phase 3, the loss of consciousness phase, lasted on average for 8.9 ± 5.1 minutes (range, 2-20 minutes).

CONCLUSIONS

The high mortality in patients with undiagnosed HAE-C1-INH underscores the need to identify these patients and diagnose their condition. The analysis of fatal laryngeal attacks gives further insight into their course, thus helping to avoid fatalities in the future.

The new era of C1-esterase inhibitor deficiency therapy

Hereditary angioedema (HAE) is an autosomal dominant disorder clinically characterized by recurrent episodes of angioedema. Until late-2008, HAE therapy in the United States was largely limited to antifibrinolytic agents or attenuated androgens. Although these drugs decrease the number and severity of angioedema attacks, they are associated with significant dose-related adverse effects. Recent advances have dramatically changed the management of HAE. As a result, we are embarking on a new era of treatment for this condition that includes effective on-demand treatment of attacks as well as effective prophylactic treatment. Herein we discuss the various treatment options for C1-inhibitor deficiency, focusing on new developments and literature published over the past year, as well as the additional patient considerations that should be addressed when determining the most appropriate patient-specific treatment plan.

C1 esterase inhibitor concentrate in 1085 Hereditary Angioedema attacks--final results of the I.M.P.A.C.T.2 study

BACKGROUND

The placebo-controlled study International Multicentre Prospective Angioedema C1-INH Trial 1 (I.M.P.A.C.T.1) demonstrated that 20 U/kg C1 esterase inhibitor (C1-INH) concentrate (Berinert®; CSL Behring, Marburg, Germany) is effective in treating acute abdominal and facial Hereditary Angioedema (HAE) attacks.

METHODS

I.M.P.A.C.T.2 was an open-label extension study of I.M.P.A.C.T.1 to evaluate the safety and efficacy of long-term treatment with 20 U/kg C1-INH for successive HAE attacks at any body location. Efficacy outcomes included patient-reported time to onset of symptom relief (primary) and time to complete resolution of all symptoms (secondary), analysed on a per-patient and per-attack basis. Safety assessments included adverse events, vital signs, viral safety and anti-C1-INH antibodies.

RESULTS

During a median study duration of 24 months, 1085 attacks were treated in 57 patients (10-53 years of age). In the per-patient analysis, the median time to onset of symptom relief was 0.46 h and was similar for all types of attacks (0.39-0.48 h); the median time to complete resolution of symptoms was 15.5 h (shortest for laryngeal attacks: 5.8 h; 12.8-26.6 h for abdominal, peripheral and facial attacks). Demographic factors, type of HAE, intensity of attacks, time to treatment, use of androgens and presence of anti-C1-INH antibodies had no clinically relevant effect on the efficacy outcomes. There were no treatment-related safety concerns. No inhibitory anti-C1-INH antibodies were detected in any patient.

CONCLUSIONS

A single dose of 20 U/kg C1-INH concentrate is safe and provides reliable efficacy in the long-term treatment of successive HAE attacks at any body location.

Therapeutic approaches in hereditary angioedema

Hereditary angioedema (HAE) is characterized by acute attacks of edema with multiple localizations, the laryngeal angioedema being the most potentially lethal. In HAE, C1-INH impairments cause episodic increase in kallikrein activity leading to attacks of angioedema. Several therapies have recently become available to treat or to prevent HAE attacks, and others are under evaluation for this indication. Plasma-derived C1-INH, bradykinin receptor antagonists (icatibant), kallikrein inhibitors (ecallantide), or recombinant C1-INH is authorized on the market for HAE attack therapy or prophylaxis. Some of these compounds can be used exclusively to treat HAE attacks, whereas others can also be used as prophylactic therapies. Such therapies, although not available worldwide, can improve disease outcome due to their different mechanisms of action.

Hereditary Angioedema: Management of Laryngeal Attacks

Background

Hereditary angioedema (HAE) patients suffering from laryngeal attacks in the United States faced severely limited treatment options until 2008. These potentially life-threatening episodes occur in over one-half of the patients affected by HAE during their lifetimes. Acute therapy had been relegated to supportive care, intubation, and consideration of fresh frozen plasma (FFP)–-the latter with the potential for actually accelerating the speed and severity of the swelling.

Methods

In this article we will review the recently approved and emerging HAE treatments that have evolved from the recognition that bradykinin generation is the fundamental abnormality leading to attacks of angioedema.

Results

Acute therapy for laryngeal attacks will be discussed including purified plasma–derived C1 inhibitor (C1INH), recombinant C1INH, an inhibitor of plasma kallikrein (ecallantide), and a B2 receptor antagonist (icatibant). Prophylactic care has also been transformed from a reliance on attenuated androgens with their attendant side effects to C1INH replacement.

Conclusion

The arrival of these novel therapies promises to transform the future management of HAE.

rhC1INH: a new drug for the treatment of attacks in hereditary angioedema caused by C1-inhibitor deficiency

Recombinant human C1 esterase inhibitor (rhC1INH) (Ruconest(®), Pharming) is a new drug developed for the relief of symptoms occurring in patients with angioedema due to C1-inhibitor deficiency. Pertinent results have already been published elsewhere; this article summarizes the progress made since then. Similar to the purified C1-inhibitor derived from human plasma, the therapeutic efficacy of rhC1INH results from its ability to block the actions of enzymes belonging to the overactivated bradykinin-forming pathway, at multiple locations. During clinical trials into the management of acute edema, a total of 190 subjects received recombinant C1-inhibitor by intravenous infusion on 714 occasions altogether. Dose-ranging efficacy studies established 50 U/kg as the recommended dose, and demonstrated the effectiveness of this agent in all localizations of hereditary angioedema attacks. Studies into the safety of rhC1INH based on 300 administrations to healthy subjects or hereditary angioedema patients followed-up for 90 days have not detected the formation of autoantibodies against rhC1INH or IgE antibodies directed against rabbit proteins, even after repeated administration on multiple occasions. These findings met favorable appraisal by the EMA, which granted European marketing authorization for rhC1INH. Pharming is expected to file a biological licence with the US FDA by the end of 2010 to obtain marketing approval in the USA. The launch of rhC1INH onto the pharmaceutical market may represent an important progress in the management of hereditary angioedema patients.

Ecallantide is a novel treatment for attacks of hereditary angioedema due to C1 inhibitor deficiency

Hereditary angioedema (HAE) resulting from the deficiency of the C1 inhibitor protein is a rare disease, characterized by paroxysms of edema formation in the subcutis and in the submucosa. Edema can cause obstruction of the upper airway, which may lead to suffocation. Prompt elimination of edema is necessary to save patients from this life-threatening condition. Essentially, these edematous attacks are related to the activation of the kinin-kallikrein system and the consequent release of bradykinin. Ecallantide (known as DX-88 previously), a potent and specific inhibitor of plasma kallikrein is an innovative medicinal product. This is the only agent approved recently by the FDA for all localizations of edematous HAE attacks. Its advantages include no risk of viral contamination, high selectivity, very rapid onset of action, good tolerability, and straightforward subcutaneous administration. Owing to the risk of anaphylaxis, ecallantide should be administered by a health care professional. A postmarketing survey to improve risk-assessment and risk-minimization has been launched. The results of these studies may lead to the approval of ecallantide for self-administration.

Hereditary angioedema: beyond international consensus - circa December 2010 - The Canadian Society of Allergy and Clinical Immunology Dr. David McCourtie Lecture

Background

The 2010 International Consensus Algorithm for the Diagnosis, Therapy and Management of Hereditary Angioedema was published earlier this year in this Journal (Bowen et al. Allergy, Asthma & Clinical Immunology 2010, 6:24 - http://www.aacijournal.com/content/6/1/24). Since that publication, there have been multiple phase III clinical trials published on either prophylaxis or therapy of hereditary angioedema and some of these products have changed approval status in various countries. This manuscript was prepared to review and update the management of hereditary angioedema.

Objective

To review approaches for the diagnosis and management of hereditary angioedema (HAE) circa December 2010 and present thoughts on moving from HAE management from international evidence-based consensus to facilitate more local health unit considerations balancing costs, efficacies of treatments, and risk benefits. Thoughts will reflect Canadian and international experiences.

Methods

PubMed searches including hereditary angioedema and diagnosis, therapy, management and consensus were reviewed as well as press releases from various pharmaceutical companies to early December 2010.

Results

The 2010 International Consensus Algorithms for the Diagnosis, Therapy and Management of Hereditary Angioedema is reviewed in light of the newly published phase III Clinical trials for prevention and therapy of HAE. Management approaches and models are discussed.

Conclusions

Consensus approach and double-blind placebo controlled trials are only interim guides to a complex disorder such as HAE and should be replaced as soon as possible with large phase IV clinical trials, meta analyses, data base registry validation of approaches including quality of life and cost benefit analyses, safety, and head-to-head clinical trials investigating superiority or non-inferiority comparisons of available approaches. Since not all therapeutic products are available in all jurisdictions and since health care delivery approaches and philosophy vary between countries, each health care delivery sector will likely devise their own algorithms based on local practicalities for implementing evidence-based guidelines and standards for HAE disease management. Quality-of-life and cost affordability benefit conclusions will likely vary between countries and health care units. Data base registries for rare disorders like HAE should be used to detect early adverse events for new therapies and to facilitate phase IV clinical trials and encourage superiority and non-inferiority comparisons of HAE management approaches.