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.

[EFFICACY, PHARMACOKINETICS, AND SAFETY OF ICATIBANT FOR THE TREATMENT OF JAPANESE PATIENTS WITH AN ACUTE ATTACK OF HEREDITARY ANGIOEDEMA: A PHASE 3 OPEN-LABEL STUDY]

BACKGROUND

Hereditary angioedema (HAE) is characterized by paroxysmal edema of the skin, gastrointestinal mucosa, and upper respiratory tract.

PURPOSE

This study investigated icatibant, a selective bradykinin B2 receptor antagonist, as treatment for Japanese patients with an acute HAE attack.

METHODS

This was an open-label, single-arm, Phase 3 study of Japanese adults with HAE type I or II. Icatibant (30 mg) was administered (by a healthcare professional [HCP] or self-administered) as a subcutaneous injection in the abdomen.

RESULTS

Eight patients (4 cutaneous, 3 abdominal, 1 laryngeal) were treated with icatibant (all single injection; 3 self-administered, 5 HCP-administered). The median time to onset of symptom relief was 1.75 hours (95% confidence interval, 1.00 to 2.50); all patients had onset of relief within 5 hours. The estimated time to maximum icatibant concentration in the circulation was 1.79 hours and the maximum concentration was 405 ng/mL. There were 3 patients who experienced 3 adverse events (2 HAE attacks and 1 headache); 7 patients experienced an injection site reaction.

CONCLUSION

Although our study was limited by the small number of patients, we found that icatibant was an effective and well-tolerated treatment for Japanese patients with acute HAE attacks, regardless of whether it was administered by a HCP or self-administered.

New Treatments for Hereditary Angioedema

Hereditary angioedema is characterized by severe, episodic edema of the subcutaneous and mucosal tissue. The disease carries significant morbidity and mortality due to involvement of the gastrointestinal tract and upper airway. Recent advances in the treatment of hereditary angioedema include new techniques used to isolate and purify human-derived C1 inhibitor, the production of a recombinant form of C1 inhibitor, and the development of drugs that target the kallikrein-kinin pathway. This paper reviews the mechanisms, efficacy, and adverse reactions associated with these medications.

Long-term safety of icatibant treatment of patients with angioedema in real-world clinical practice

The Icatibant Outcome Survey (IOS) is an observational study monitoring safety and effectiveness of icatibant in the real‐world setting. We analyzed safety data from 3025 icatibant‐treated attacks in 557 patients (enrolled between July 2009 and February 2015). Icatibant was generally well tolerated. Excluding off‐label use and pregnancy, 438 patients (78.6%) did not report adverse events (AEs). The remaining 119 (21.4%) patients reported 341 AEs, primarily gastrointestinal disorders (19.6%). Of these, 43 AEs in 17 patients (3.1%) were related to icatibant. Serious AEs (SAEs) occurred infrequently. A total of 143 SAEs occurred in 59 (10.6%) patients; only three events (drug inefficacy, gastritis, and reflux esophagitis) in two patients were considered related to icatibant. Notably, no SAEs related to icatibant occurred in patients with cardiovascular disease, nor in those using icatibant at a frequency above label guidelines. Additionally, no major differences were noted in AEs occurring in on‐label vs off‐label icatibant users.

Pediatric Hereditary Angioedema as a Cause of Acute Compartment Syndrome of the Hand and Forearm: A Case Report

BACKGROUND

Compartment syndrome of the upper extremity is a surgical emergency that, when left untreated, can have dire consequences. Its causes are numerous, one of which is the uncommon entity hereditary angioedema, an autosomal dominant disease resulting in edema in a variety of potential locations, including the extremities. This is only the second time hereditary angioedema has been mentioned in the literature as a cause of compartment syndrome.

METHODS

We present a case of hereditary angioedema leading to hand and forearm compartment syndrome in a 13-year-old pediatric patient. Diagnosis of hereditary angioedema was made by our Rheumatology colleagues with physical exam and a thorough history, and confirmed by laboratory studies.

RESULTS

Our patient presented with compartment syndrome of the hand and forearm and underwent hand and volar forearm fasciotomies. She was subsequently worked up for hereditary angioedema with laboratory results confirming the diagnosis. She was discharged after a 5-day hospitalization with prophylactic C1-inhibitor therapy.

CONCLUSIONS

Hereditary angioedema is a rare but known cause of compartment syndrome of the upper extremity, and must be considered when patients present with compartment syndrome of unknown etiology. This disease can be diagnosed by laboratory studies and symptoms can be controlled with medical therapy.

Comparing acquired angioedema with hereditary angioedema (types I/II): findings from the Icatibant Outcome Survey

Icatibant is used to treat acute hereditary angioedema with C1 inhibitor deficiency types I/II (C1-INH-HAE types I/II) and has shown promise in angioedema due to acquired C1 inhibitor deficiency (C1-INH-AAE). Data from the Icatibant Outcome Survey (IOS) were analysed to evaluate the effectiveness of icatibant in the treatment of patients with C1-INH-AAE and compare disease characteristics with those with C1-INH-HAE types I/II. Key medical history (including prior occurrence of attacks) was recorded upon IOS enrolment. Thereafter, data were recorded retrospectively at approximately 6-month intervals during patient follow-up visits. In the icatibant-treated population, 16 patients with C1-INH-AAE had 287 attacks and 415 patients with C1-INH-HAE types I/II had 2245 attacks. Patients with C1-INH-AAE versus C1-INH-HAE types I/II were more often male (69 versus 42%; P = 0·035) and had a significantly later mean (95% confidence interval) age of symptom onset [57·9 (51·33-64·53) versus 14·0 (12·70-15·26) years]. Time from symptom onset to diagnosis was significantly shorter in patients with C1-INH-AAE versus C1-INH-HAE types I/II (mean 12·3 months versus 118·1 months; P = 0·006). Patients with C1-INH-AAE showed a trend for higher occurrence of attacks involving the face (35 versus 21% of attacks; P = 0·064). Overall, angioedema attacks were more severe in patients with C1-INH-HAE types I/II versus C1-INH-AAE (61 versus 40% of attacks were classified as severe to very severe; P < 0·001). Median total attack duration was 5·0 h and 9·0 h for patients with C1-INH-AAE versus C1-INH-HAE types I/II, respectively.

Hereditary angioedema with normal C1 inhibitor in a French cohort: Clinical characteristics and response to treatment with icatibant

Introduction

The clinical characteristics and icatibant‐treatment outcomes of patients with hereditary angioedema with normal C1 inhibitor (HAE‐nC1 INH) are limited.

Methods

We retrospectively analyzed data from French HAE patients enrolled in the Icatibant Outcome Survey registry (from July 2009 to September 2013) to compare disease characteristics and the effectiveness and safety of acute icatibant‐treated angioedema attacks in patients with HAE‐nC1 INH, HAE with C1 INH deficiency (type I), or dysfunction (type II).

Results

One center in Grenoble contributed 22 patients with HAE‐nC1 INH and a family history of HAE while 15 centers across France contributed 153 patients with HAE type I and seven patients with HAE type II. Patients with HAE‐nC1 INH compared to HAE type I, respectively, were more likely to be female (88.1% vs. 63.4%), older at median age of disease onset (21 years vs. 15 years), and have a greater rate of abdominal (80% vs. 61%) and laryngeal (23% vs. 14%) attacks. Icatibant was effective in both groups though the median time to resolution of attack was significantly longer in the HAE‐nC1 INH group (20.0 h, 37 attacks) versus the HAE type I group (14.0 h, 67 attacks). Icatibant was self‐administered for 96.1% of attacks in patients with HAE‐nC1 INH and 75.8% in patients with HAE type I. No serious adverse side effects related to icatibant were reported.

Conclusions

These data help further define the disease characteristics of HAE‐nC1 INH in the French population and extend the limited data reporting the safe and effective use of icatibant in acute treatment of angioedema in French patients diagnosed with HAE‐nC1 INH.

Effect of bradykinin receptor antagonism on ACE inhibitor-associated angioedema

BACKGROUND

The B₂ receptor antagonist icatibant is approved for treatment of attacks of hereditary angioedema. Icatibant has been reported to decrease time-to-resolution of angiotensin-converting enzyme (ACE) inhibitor-associated angioedema in 1 study of European patients.

OBJECTIVE

We sought to test the hypothesis that a bradykinin B₂ receptor antagonist would shorten time-to-resolution from ACE inhibitor-associated angioedema.

METHODS

Patients with ACE inhibitor-associated angioedema (defined as swelling of lips, tongue, pharynx, or face during ACE inhibitor use and no swelling in the absence of ACE inhibitor use) were enrolled at Vanderbilt University Medical Center from October 2007 through September 2015 and at Massachusetts General Hospital in 2012. C1 inhibitor deficiency and patients with bowel edema only were excluded. Patients were randomized within 6 hours of presentation to subcutaneous icatibant 30 mg or placebo at 0 and 6 hours later. Patients assessed severity of swelling using a visual analog scale serially following study drug administration or until discharge.

RESULTS

Thirty-three patients were randomized and 31 received treatment, with 13 receiving icatibant and 18 receiving placebo. One patient randomized to icatibant did not complete the visual analog scale and was excluded from analyses. Two-thirds of patients were black and two-thirds were women. Time-to-resolution of symptoms was similar in placebo and icatibant treatment groups (P = .19 for the primary symptom and P > .16 for individual symptoms of face, lip, tongue, or eyelid swelling). Frequency of administration of H1 and H2 blockers, corticosteroids, and epinephrine was similar in the 2 treatment groups. Time-to-resolution of symptoms was similar in black and white patients.

CONCLUSIONS

This study does not support clinical efficacy of a bradykinin B₂ receptor antagonist in ACE inhibitor-associated angioedema.

Managing the female patient with hereditary angioedema

Hereditary angioedema (HAE) is a rare disorder resulting from decreased functional levels of C1-inhibitor (C1-INH), which manifests as periodic episodes of localized edema which can be extremely painful, debilitating and even fatal if the swelling affects the larynx. HAE can complicate many aspects of obstetric/gynecologic care, and an awareness of the disease is critical for clinicians involved in the care of women because of potential HAE-related complications pertaining to pregnancy, labor and delivery, and other women's health issues. This article provides a review of published literature specific to HAE and its management in female patients, including important concerns regarding obstetric/gynecologic care. A growing body of relevant experience is presented to help guide the care of women with HAE.

Contribution of the Kallikrein/Kinin System to the Mediation of ConA-Induced Inflammatory Ascites

Intraperitoneal administration of concanavalin A (ConA, 25 mg/kg b.w.), a cell-binding plant lectin was used for inducing inflammatory ascites, and potential inhibitors were tested in 1 h and 2.5 h experiments, i.e. still before the major influx of leucocytes. At the end of the experiment the peritoneal fluid was collected and measured. The ConA-induced ascites was significantly (p<0.01) and dose-dependently inhibited by icatibant (HOE-140), a synthetic polypeptide antagonist of bradykinin receptors. Aprotinin, a kallikrein inhibitor protein also had significant (p<0.01), but less marked inhibitory effect. L-NAME, an inhibitor of NO synthesis, and atropine methylnitrate, an anticholinergic compound, were ineffective. It is concluded, that the kallikrein/kinin system contributes to the mediation of the ConA-induced ascites by increasing subperitoneal vascular permeability, independent of the eventual vasodilation produced by NO. It is known, that membrane glycoproteins are aggregated by the tetravalent ConA and the resulting distortion of membrane structure may explain the activation of the labile prekallikrein. Complete inhibition of the ConA-induced ascites could not be achieved by aprotinin or icatibant, which indicates the involvement of additional mediators.

Efficacy of on-demand treatment in reducing morbidity in patients with hereditary angioedema due to C1 inhibitor deficiency

BACKGROUND

Angioedema due to hereditary deficiency of C1 inhibitor causes temporarily disability. Guidelines recommend early on-demand treatment of attacks to reduce morbidity. In this prospective observational study, we evaluated the efficacy of on-demand approach.

METHODS

From January 2009 to August 2014, data on attacks and treatments were collected from 227 patients from our centre in Milan.

RESULTS

A total of 4244 attacks were reported; 50% were treated with approved therapies (pdC1-INH or icatibant), 15% were with tranexamic acid, and 35% were not treated. Attack locations were peripheral cutaneous (46%), abdominal (34%), multiple (12%), facial (5%) and laryngeal (3%). Attack severities were moderate (48%), mild (28%) and severe (24%). Median attack duration (data available for 2393 attacks) with approved therapies was 10 h, significantly shorter than without treatment (45 h) or with tranexamic acid (38 h). Most of the treatments were self-administered: 93% with icatibant and 59% with pd-C1-INH. Median attack duration with icatibant was 8 and 11.5 h with pd-C1 INH. Median time from onset of symptoms to drug administration was 1 h with icatibant and 2 h with pd-C1INH and median time from drug administration to complete resolution was 5.5 and 8 h, respectively. Second treatment was required in 12.7% of icatibant-treated attacks and in 1.9% of pdC1-INH-treated attacks.

CONCLUSION

This study provides evidence that on-demand treatment is effective in reducing disease-related morbidity. The use of on-demand treatment in Italy has increased up to 50% of attacks in the last years, reflecting a better adherence to international guidelines.

Optimizing hereditary angioedema management through tailored treatment approaches

Hereditary angioedema (HAE) is a rare but serious and potentially life threatening autosomal dominant condition caused by low or dysfunctional C1 esterase inhibitor (C1-INH) or uncontrolled contact pathway activation. Symptoms are characterized by spontaneous, recurrent attacks of subcutaneous or submucosal swellings typically involving the face, tongue, larynx, extremities, genitalia or bowel. The prevalence of HAE is estimated to be 1:50,000 without known racial differences. It causes psychological stress as well as significant socioeconomic burden. Early treatment and prevention of attacks are associated with better patient outcome and lower socioeconomic burden. New treatments and a better evidence base for management are emerging which, together with a move from hospital-centered to patient-centered care, will enable individualized, tailored treatment approaches.

The safety of treatments for angioedema with hereditary C1 inhibitor deficiency

INTRODUCTION

Angioedema is a localized and self-limiting edema of the subcutaneous and submucosal tissue. Hereditary angioedema with C1 inhibitor deficiency (C1-INH-HAE) is the best characterized form of hereditary angioedema. In C1-INH-HAE, the reduced plasma levels of C1-INH cause instability of the contact system with release of bradykinin, the key mediator of angioedema. C1-INH-HAE is characterized by recurrent skin swelling, abdominal pain, and potentially life-threatening upper airways obstruction. Knowledge of the molecular mechanisms leading from C1-INH deficiency to angioedema allowed the development of several therapies.

AREAS COVERED

The aim of this review article is to discuss the safety of currently available treatments of C1-INH-HAE. The authors give an insight on the mechanism of action and safety profile of drugs for treatment of acute attacks and for short- and long-term prophylaxis. Evidence from systematic reviews, clinical trials, retrospective studies, and case reports is summarized in this review.

EXPERT OPINION

C1-INH-HAE is a disabling, life-threatening condition that lasts life-long. Different therapeutic approaches with different drugs provide significant benefit to patients. Safety profiles of these therapies are critical for optimal therapeutic decision and need to be known by C1-INH-HAE treating physicians for appropriate risk/benefit evaluation.

Angioedema induced by cardiovascular drugs: new players join old friends

During the last years, two new cardiovascular drug classes, namely inhibitors of DPP IV or neprilysin, have been developed. In both cases, there is clinical evidence for their potential to induce angioedema as known already from blockers of the renin-angiotensin-aldosterone system (RAAS). The majority of angioedema induced by DPP IV inhibitors occurs during concomitant treatment with ACEi and is therefore likely mediated by overactivation of bradykinin type 2 receptors (B2). In striking contrast, the molecular pathways causing angioedema induced by neprilysin inhibitors, that is, sacubitril, are unclear, although a contribution of bradykinin appears likely. Nevertheless, there is no clinical evidence suggesting that inhibition of B2 might relieve the symptoms and/or prevent invasive treatment including coniotomy or tracheotomy in angioedema caused by these drugs. Therefore, the risk of angioedema should always be considered, especially in ambulatory care situations where patients have no rapid access to intensive care.

Stability of murine bradykinin type 2 receptor despite treatment with NO, bradykinin, icatibant, or C1-INH

BACKGROUND

Little is known about factors which trigger and/or contribute to hereditary angioedema or ACE-inhibitor-mediated angioedema including variations in bradykinin type 2 receptor (B2R) expression and activity.

METHODS

Protein and mRNA expression of B2R and the increase of intracellular calcium (iCa) in response to bradykinin were monitored in porcine and murine endothelial cells in response to NO donors or bradykinin. B2R protein expression was evaluated in skin, heart, and lung of (i) mice with endothelial-specific overexpression of eNOS (eNOS(tg) ), (ii) in eNOS(-/-) mice and (iii) in C57BL/6 mice treated with the NO donor pentaerythritol tetranitrate (PETN), the NOS inhibitor l-nitroarginine (L-NA), plasma pool C1-INH, and the B2R antagonist icatibant. Aortic reactivity to bradykinin was investigated including eNOS(-/-) mice.

RESULTS

B2R protein and mRNA expression remained unchanged in cells subjected to L-NA, NO donors, and bradykinin in a time- and concentration-dependent manner. Likewise, increases of iCa in murine brain endothelial cells remained unchanged. B2R protein levels were similar in eNOS(tg) and eNOS(-/-) as compared to transgene-negative littermates. Likewise, treatment of C57BL/6 mice with PETN, L-NA, C1-INH or icatibant did not change B2R protein expression. In aortic rings of C57BL/6 mice, bradykinin induced B2R-dependent constrictions which were attenuated by endothelial NO and abolished by diclofenac indicating the functional importance of B2R-induced activation of endothelial NO synthase and cyclooxygenase.

CONCLUSION

These data suggest that alterations of B2R protein expression induced by NO, bradykinin, C1-INH, or icatibant unlikely contribute to bradykinin-induced angioedema. This finding does not rule out a role for NO in bradykinin-induced extravasation and/or angioedema.

Severe Puumala virus infection in a patient with a lymphoproliferative disease treated with icatibant

Early identification of patients at risk of a severe course of hantaviral disease and lack of effective medication represent a global challenge in the treatment of this emerging infection. We describe a 67-year-old female patient with a history of chronic lymphoproliferative disease involving the spleen and an extremely severe acute Puumala hantavirus infection. She was treated with the bradykinin receptor antagonist icatibant and recovered. She is the second patient with a spleen abnormality and severe Puumala infection treated with icatibant in our hospital. We suggest that patients with spleen abnormalities may be more susceptible to severe hantavirus disease. The activation of the kinin-kallikrein system and the formation of bradykinin in hantavirus-infected endothelial cells indicate that the role of bradykinin receptor antagonist icatibant in the treatment of hantavirus disease is worth studying.

Repeat treatment of acute hereditary angioedema attacks with open-label icatibant in the FAST-1 trial

Hereditary angioedema (HAE) is characterized by potentially life-threatening recurrent episodes of oedema. The open-label extension (OLE) phase of the For Angioedema Subcutaneous Treatment (FAST)-1 trial (NCT00097695) evaluated the efficacy and safety of repeated icatibant exposure in adults with multiple HAE attacks. Following completion of the randomized, controlled phase, patients could receive open-label icatibant (30 mg subcutaneously) for subsequent attacks. The primary end-point was time to onset of primary symptom relief, as assessed by visual analogue scale (VAS). Descriptive statistics were reported for cutaneous/abdominal attacks 1-10 treated in the OLE phase and individual laryngeal attacks. Post-hoc analyses were conducted in patients with ≥ 5 attacks across the controlled and OLE phases. Safety was evaluated throughout. During the OLE phase, 72 patients received icatibant for 340 attacks. For cutaneous/abdominal attacks 1-10, the median time to onset of primary symptom relief was 1·0-2·0 h. For laryngeal attacks 1-12, patient-assessed median time to initial symptom improvement was 0·3-1·2 h. Post-hoc analyses showed the time to onset of symptom relief based on composite VAS was consistent across repeated treatments with icatibant. One injection of icatibant was sufficient to treat 88·2% of attacks; rescue medication was required in 5·3% of attacks. No icatibant-related serious adverse events were reported. Icatibant provided consistent efficacy and was well tolerated for repeated treatment of HAE attacks.

Repeat treatment with icatibant for multiple hereditary angioedema attacks: FAST-2 open-label study

BACKGROUND

The For Angioedema Subcutaneous Treatment (FAST)-2, a phase III, double-blind, randomized, multicenter, placebo-controlled study (ClinicalTrials.gov identifier: NCT00500656), established the efficacy and safety of single injections of icatibant, a bradykinin B₂ receptor antagonist, in the treatment of hereditary angioedema (HAE) attacks. Here, we evaluate the efficacy and safety of repeated treatment with icatibant in adult patients experiencing HAE attacks during the FAST-2 open-label extension (OLE) phase.

METHODS

Patients completing the controlled phase were eligible to participate in the OLE phase and receive open-label icatibant (30 mg subcutaneously) for the treatment of cutaneous, abdominal, and/or laryngeal HAE attack(s) severe enough to warrant treatment. Time to onset of symptom relief was calculated for each attack. Descriptive analyses (median, 95% CIs) were performed for all attacks; post hoc analyses were conducted in patients with at least five icatibant-treated attacks throughout the FAST-2 OLE phase. Safety was also monitored.

RESULTS

Fifty-four patients received icatibant for 374 attacks (176 cutaneous, 168 abdominal, and 30 laryngeal). For cutaneous and/or abdominal attacks (attacks 2-5), the median times to onset of symptom relief ranged between 2.0 and 2.5 h. For all laryngeal attacks, the median times to regression (start of improvement) of symptoms ranged between 0.3 and 4.0 h. Post hoc analyses showed that the overall median time to onset of symptom relief was 2.0 h. Overall, 89.8% of attacks resolved with a single icatibant injection. No drug-related serious adverse events were reported.

CONCLUSIONS

These findings have demonstrated the efficacy and safety of repeated icatibant treatment for HAE attacks.

Hereditary angioedema: epidemiology, management, and role of icatibant

Hereditary angioedema (HAE) is an autosomal dominant, potentially life-threatening condition, manifesting as recurrent and self-limiting episodes of facial, laryngeal, genital, or peripheral swelling with abdominal pain secondary to intra-abdominal edema. The estimated prevalence of HAE in the general population is one individual per 50,000, with reported ranges from 1:10,000 to 1:150,000, without major sex or ethnic differences. Various treatment options for acute attacks and prophylaxis of HAE are authorized and available in the market, including plasma-derived (Berinert®, Cinryze®, and Cetor®) and recombinant (Rhucin® and Ruconest™) C1 inhibitors, kallikrein inhibitor-ecallantide (Kalbitor®), and bradykinin B2 receptor antagonist-icatibant (Firazyr®). Some of these drugs are used only to treat HAE attacks, whereas others are only approved for prophylactic therapies and all of them have improved disease outcomes due to their different mechanisms of action. Bradykinin and its binding to B2 receptor have been demonstrated to be responsible for most of the symptoms of HAE. Thus icatibant (Firazyr®), a bradykinin B2 receptor antagonist, has proven to be an effective and more targeted treatment option and has been approved for the treatment of acute attacks of HAE. Rapid and stable relief from symptoms of cutaneous, abdominal, or laryngeal HAE attacks has been demonstrated by 30 mg of icatibant in Phase III clinical trials. Self-resolving mild to moderate local site reactions after subcutaneous injection of icatibant were observed. Icatibant is a new, safe, and effective treatment for acute attacks of HAE. HAE has been reported to result in enormous humanistic burden to patients, affecting both physical and mental health, with a negative impact on education, career, and work productivity, and with substantial economic burdens. The timely and proper use of disease-specific treatments could improve patients’ quality of life, reduce the disease-specific morbidity and mortality, and, last but not least, reduce costs associated with hospitalizations and emergency room visits. Therefore, the paradigm of HAE treatment has the potential to evolve significantly, thereby exponentially improving a patient’s quality of life.

Social costs of icatibant self-administration vs. health professional-administration in the treatment of hereditary angioedema in Spain

BACKGROUND

Icatibant is the only subcutaneous treatment for acute Type I and Type II hereditary angioedema with C1-esterase inhibitor deficiency (HAE-C1-INH) licensed for self-administration in Europe.

AIM

To compare the economic impact of two icatibant administration strategies: health professional-administration only (strategy 1) versus including the patient self-administration option (strategy 2).

METHODS

Economic evaluation model based on the building of a decision tree. Both strategies are assumed to have equivalent effectiveness. The payer (Spanish National Health System) and the social perspectives were considered. All relevant cost-generating factors were taken into account. The time horizon was one year. Sources of information included scientific evidence, official data and experts' opinion. A deterministic sensitivity analysis was carried out to quantify the underlying uncertainty in the model.

RESULTS

From the social perspective, which considers both direct (health care costs) and indirect costs (productivity losses), strategy 2 would result into average savings of €121.30 per acute attack compared to strategy 1. For Spain, this would achieve in an annual savings of €551,371. The reduction in direct costs accounts for 74% of the savings and lower indirect costs account for the remaining 26%. Savings per acute attack may range from €79.50 to €169.80; accordingly, the annual savings in Spain may vary between €90,319 and €2,315,360.

CONCLUSION

Costs related to the management of acute HAE attacks with C1 inhibitor deficiency may be substantially reduced through interventions targeting home treatment by training patients to self-administer icatibant.

An evidence-based review of the potential role of icatibant in the treatment of acute attacks in hereditary angioedema type I and II

INTRODUCTION

Icatibant, a first-in-class B2 bradykinin receptor antagonist, appears to have a favorable efficacy and safety profile for the treatment of acute attacks of hereditary angioedema in adults.

AIMS

To update the evidence and provide an overview of the available data on icatibant.

EVIDENCE REVIEW

Peer reviewed articles published and listed in Medline Search and published updated guidelines for the treatment of acute attacks in hereditary angioedema type I and II in adults were reviewed. The validity and quality of evidence were evaluated.

PLACE IN THERAPY

Clinical evidence for the treatment of acute hereditary angioedema attacks with icatibant is strong. Approximately 10% of the patients require a second dose. No serious adverse reactions have been reported. The only significant side effects consistently registered by 90% of patients are transient local pain, swelling, and erythema at the local injection site.

CONCLUSION

Subcutaneously administered 30 mg icatibant has been shown to be a safe and efficacious treatment in clinical trials. It is the only specific treatment authorized for self-administration by the subcutaneous route offering increased patient independence.

Comparison of the molecular interactions of two antagonists, MEN16132 or icatibant, at the human kinin B₂ receptor

BACKGROUND AND PURPOSE

Icatibant is a well-known kinin B₂ receptor antagonist currently used for angiooedema attacks. MEN16132 is a non-peptide B₂ receptor antagonist, more potent and long lasting than icatibant in different models. Here we studied the reasons for these differences between the two antagonists.

EXPERIMENTAL APPROACH

Rate of reversibility (over about 3 h) of the functional receptor blockade exerted by the antagonists was compared (inositol phosphates accumulation assay) in CHO cells expressing the human B₂ receptor and in human synovial cells. Antagonist pretreated cells were washed with medium and the time taken to restore bradykinin (BK) response measured. Antagonist affinity was measured by radioligand binding to wild type and mutated B₂ receptors.

KEY RESULTS

Recovery of BK-induced responses was slower in cells pretreated with MEN16132 than in those treated with icatibant. The affinity of icatibant (for the [³H]-BK or the B₂ receptor antagonist [³H]-MEN11270 binding site) was compared to that of MEN16132 using a panel of point-mutated receptors with mutations located at the transmembrane regions of the B₂ receptor, previously shown to decrease MEN16132 high affinity interaction. No consistent decrease of icatibant affinity was observed. From the different affinity of MEN16132 derivatives at wild type and W86A (transmembrane 2 region) receptors, and by evaluating its antagonist profile at the D266A/D284A double mutant receptor, a model of the MEN16132-B₂ receptor complex is proposed.

CONCLUSIONS AND IMPLICATIONS

MEN16132 dissociated from the B₂ receptor compartment more slowly than icatibant and interacted at a deeper level in transmembrane regions of the receptor.

Bradykinin and B₂ receptor antagonism in rat and human articular chondrocytes

BACKGROUND AND PURPOSE

In osteoarthritis (OA), bradykinin (BK) is known to contribute to pain and synovitis, but not to cartilage degradation. Here, we investigated effects of BK and its antagonists on chondrocytes, cells involved in cartilage homeostasis.

EXPERIMENTAL APPROACH

BK receptor density and affinities of BK, its analogues and antagonists were measured in cultured human and rat chondrocytes by radioligand binding. Effects of BK were assessed by accumulation of inositol phosphates (IP) and release of interleukin (IL)-6 and IL-8.

KEY RESULTS

Density of [³H]-BK binding sites was higher (13-30-fold) and BK evoked a greater (48-fold) IP production, in human than in rat chondrocytes. The BK B₂ receptor antagonists MEN16132 and icatibant displayed similar binding affinity. MEN16132 was 40-fold more potent than icatibant in the IP assay. In human chondrocytes, BK increased release (over 24 h) of IL-6 and IL-8, effects blocked by MEN16132 but not by the B₁ receptor antagonist Lys-[Leu⁸][desArg⁹]BK. BK-induced release of IL-6, but not of IL-8, was partially inhibited by indomethacin (10 µM) and nordihydroguaiaretic acid (10 µM). Antagonists for the prostanoid EP receptors (AH6809 10 µM; L-798,196, 200 nM; L-161,982, 1 µM) were ineffective. Dexamethasone (100 nM) partially inhibited release of both IL-6 and IL-8. Inhibitors of intracellular downstream signalling pathways (SB203580 10 µM; PD98059, 30 µM; SP600125, 30 µM; BAY-117085, 5 µM) indicated the involvement of p38 MAPK and the activation of NF-κB.

CONCLUSION AND IMPLICATIONS

BK mediated inflammatory changes and cartilage degradation and B₂ receptor blockade would, therefore, be a potential treatment for OA.

Management of acute attacks of hereditary angioedema: potential role of icatibant

Icatibant (Firazyr(®)) is a novel subcutaneous treatment recently licensed in the European Union for acute hereditary angioedema. Hereditary angioedema, resulting from inherited partial C1 inhibitor deficiency, is a disabling condition characterized by intermittent episodes of bradykinin-mediated angioedema. Icatibant blocks bradykinin B2 receptors, attenutating the episode. Randomized double-blind, placebo-controlled trials of icatibant, showed significant superiority over oral tranexamic acid in 74 European patients and a trend to improvement in a similar US trial comparing icatibant with placebo in 55 patients. Outcomes for several endpoints did not reach significance in the US trial, perhaps because of low participant numbers and confounding factors: a further trial is planned. Open label studies have shown benefit in multiple treatments for attacks at all sites. Approximately 10% of patients require a second dose for re-emergent symptoms, usually 10 to 27 hours after the initial treatment. Its subcutaneous route of administration, good tolerability and novel mode of action make icatibant a promising addition to the limited repertoire of treatments for hereditary angioedema.