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

A Comprehensive Management Approach in Pediatric and Adolescent Patients With Hereditary Angioedema

Hereditary angioedema (HAE) is a rare autosomal-dominant disorder; most cases are characterized by low plasma levels of C1 esterase inhibitor (C1-INH). Clinical manifestations of HAE due to C1-INH deficiency include unpredictable, acute, recurrent episodes of nonpruritic swelling that can affect the face, trunk, limbs, and the respiratory, gastrointestinal, and genitourinary tracts. Attacks can be disfiguring, disabling, painful, and even life-threatening if laryngeal swelling occurs. Symptoms of HAE generally manifest in childhood. Effective medications are available and approved to treat HAE in children. However, evidence informing use of these medications in pediatric clinical practice is limited. Hereditary angioedema management plans are critical to optimize outcomes and should address on-demand treatment for acute attacks and plans to prevent potentially fatal laryngeal attacks. The plan should also comprise a holistic approach to address nonclinical aspects of HAE, including quality of life (QoL) and psychological issues. This article provides an overview of HAE management principles that health care providers can apply to treat pediatric patients to improve their QoL.

A Case of Refractory Angioedema

Angioedema is an acute disorder that affects mucous membranes and the deepest layers of the skin along with underlying tissue, marked by rapid swelling, large welts, and pain. There are 3 major subtypes of angioedema: mast-cell mediated, bradykinin-mediated, and multifactorial or unclear mechanism subtype. The most common subtype of bradykinin-mediated angioedema is ACE-inhibitor induced, which disproportionately affects African-Americans. It is most often self-limiting and usually responds to the withdrawal of the offending agent. The prolonged duration of angioedema is uncommon in the absence of a persistent stimulus, though it is more likely when there is an abnormality of the metabolic pathways, such as in hereditary angioedema or other gene polymorphisms affecting the complement system. We present a case of severe angioedema that persisted for over a month and required a tracheostomy to manage the airway.

The Role of Bradykinin Receptors in Hereditary Angioedema Due to C1-Inhibitor Deficiency

Background: Hereditary angioedema (HAE) is a rare, genetic disease caused by the decreased level or function of the C1 inhibitor. The primary mediator of symptoms in HAE is bradykinin acting through its two receptors, namely receptors 1 (BR1) and 2 (BR2). Although BR2 is well characterized, the role of BR1 remains unclear. Objective: To study the role of bradykinin receptors 1 (BR1) in the etiopathogenesis of HAE. Methods: A total of 70 individuals, 40 patients with HAE, and 30 healthy subjects were recruited to the study. HAE was diagnosed in accordance with the international guideline. The level of bradykinin receptors was determined in populations of CD3⁺, CD4⁺, CD8⁺, and CD14⁺⁺CD16⁻, CD14⁺⁺CD16⁺ monocytes. In addition, the level of disease activity-specific markers was measured. Results: There were statistically significant differences in the subpopulation of lymphocytes and monocytes between patients with HAE compared to healthy subjects. The level of BR1 and BR2 on PBMCs was comparable in healthy subjects and HAE patients during remission with significant overexpression of both receptors, triggered by HAE attack. Moreover, a significant increase in TNF-alpha and IL-1 plasma levels was observed among HAE patients. Conclusions: BR1 expression may play an important role in the pathomechanism of HAE.

The Icatibant Outcome Survey: 10 years of experience with icatibant for patients with hereditary angioedema

In patients with hereditary angioedema (HAE), bradykinin causes swelling episodes by activating bradykinin B₂ receptors. Icatibant, a selective bradykinin B₂ receptor antagonist, is approved for on-demand treatment of HAE attacks. The Icatibant Outcome Survey (IOS; NCT01034969) is an ongoing observational registry initiated in 2009 to monitor effectiveness/safety of icatibant in routine clinical practice. As of March 2019, 549 patients with HAE type 1 or 2 from the IOS registry had been treated, for 5995 total attacks. This article reviews data published from IOS over time which have demonstrated that effectiveness of icatibant in a real-world setting is comparable to efficacy in clinical trials; one dose is effective for the majority of attacks; early treatment (facilitated by self-administration) leads to faster resolution and shorter attack duration; effectiveness/safety of icatibant has been shown across a broad range of patient subgroups, including children/adolescents and patients with HAE with normal C1 inhibitor levels; and tolerability has been demonstrated in patients aged ≥65 years. Additionally, this review highlights how IOS data have provided valuable insights into patients' diagnostic journeys and treatment behaviors across individual countries. Such findings have helped to inform clinical strategies and guidelines to optimize HAE management and limit disease burden. This research was sponsored by Takeda Development Center Americas, Inc. Takeda Development Center Americas, Inc., provided funding to Excel Medical Affairs for support in writing and editing this manuscript.

Orphan Drug Use in Patients With Rare Diseases: A Population-Based Cohort Study

Background: Orphan drugs are used for the diagnosis, prevention and treatment of rare diseases that, in the European Union, are defined as disorders affecting no more than 5 persons in 10,000. So far, a total of around 800 orphan medicinal products have been approved by the European Medicines Agency, however the utilization profile of orphan drugs has yet to be explored. This study aimed at assessing the utilization profile of orphan drugs authorized for marketing by the Italian Medicines Agency using population-based data.

Methods: A total of 21 orphan drugs used in outpatient settings, approved in the European Union before or during the 2008–2018 period and involving 15 rare diseases, were included in the study. The monitored population included patients with one of the conditions surveilled by the population-based Tuscany Registry of Rare Diseases and diagnosed between 2000–2018. A multi-database approach was applied, by linking data from the registry with information collected in drug prescriptions databases. The prevalence and intensity of use were estimated for the selected orphan drugs and other non-orphan medications, used to treat the same rare disease and for which a change in the prevalence of use was hypothesized after authorization of the orphan drug.

Results: For some diseases (acquired aplastic anemia, tuberous sclerosis complex, most metabolic diseases) a low prevalence of orphan drugs use was observed (range between 1.1–12.5%). Conversely, orphan drugs were frequently used in hemophilia B, Wilson disease and idiopathic pulmonary fibrosis (maximum of 78.3, 47.6 and 41.8%, respectively). For hemophilia B and Leber’s hereditary optic neuropathy, there are currently no other medications used in clinical practice in addition to orphan drugs. Six orphan drugs were used for the treatment of pulmonary arterial hypertension, appearing the elective therapy for this disease, albeit with different utilization profiles (range of prevalence 1.7–55.6%).

Conclusion: To the best of our knowledge, this is the first study investigating the utilization profile of orphan drugs prescribed in a defined geographical area, and providing relevant information to monitor over time potential changes in the prevalence of these medications as well as in the health care decision making.

How satisfactory is on-demand icatibant from the patients' perspective in real life?

Background: Patients' satisfaction is important for the success of the management of chronic diseases. Objective: Our aim was to evaluate the satisfaction level of the patients with hereditary angioedema (HAE) for icatibant treatment. Methods: Patients with HAE C1 esterase inhibitor (C1-INH) were evaluated by using a questionnaire that included details of their icatibant-treated attacks. Patients' demographic and clinical features were collected from their medical records and personal attack diaries. The visual analog scale was used for determining the attack severity. Results: Of the total 161 patients with HAE C1-INH, 91% had HAE type I and were included in the study. Patients reported a median (interquartile range [IQR]) attacks of 2 (0.5-3) per month and 16 (4.5-36) attacks per year. The median (IQR) frequency of attacks treated with icatibant was 6 (0-20) per year. The mean ± standard deviation (SD) duration of treatment with icatibant was 3 ± 2.3 years. The self-administration rate was 91.3%. The mean ± SD time to administration and time to onset of symptom resolution were 1.6 ± 1.1 hours and 1.7 ± 1.3 hours, respectively. There was a correlation between the time to administration and time to onset of symptom resolution (r = 0.566; p < 0.0001). A total of 125 patients (77%) reported that they were very satisfied or satisfied with icatibant. No correlation was observed between the satisfaction level and the attack sites; however, the patients with more severe attacks were more satisfied with icatibant (p < 0.0001). A total of 52 patients reported 74 mild local reactions. Systemic reactions were not observed. Conclusion: The current real-life study showed that icatibant was safe and effective. Moreover, the patients' satisfaction level with icatibant was high. We believe that the availability of icatibant should be encouraged during HAE attacks because it enables patients to be more involved in their disease management.

National Audit of a Hereditary and Acquired Angioedema Cohort in New Zealand

BACKGROUND

HAE leads to significant morbidity and mortality from unpredictable intermittent peripheral, abdominal and laryngeal swelling. Access to appropriate healthcare and effective therapies which can prevent and treat attacks, reduce the suffering and greatly improve quality of life. Although treatments such as C1 inhibitor (Berinert®), and Icatibant® are available in New Zealand (Aotearoa), there is no published data available on their use.

AIMS

This study presents a national audit of Hereditary Angioedema (HAE) and Acquired Angioedema (AAE) in 2019.

RESULTS

The total number of known adult (48) and children (3) HAE and Acquired Angioedema (3) patients is 54. Of these, 41/ 54 (75%) of HAE and AAE patients were recruited to the audit. Icatibant® has been available for treatment of acute HAE attacks since 2016, and is now used in 73% of HAE patients. Icatibant® is also used by patients for laryngeal attacks in the community, who may not then present to hospital. Androgens are used in half of the patients as prophylaxis but 33% of the latter were identified as not having regular liver ultrasound screening. Tranexamic acid is used as prophylaxis in one fifth of patients. Participants have had 40 children, half of whom may be affected. Three have been diagnosed with HAE, suggesting that the majority have not yet been tested.

CONCLUSIONS

Corrective actions arising from this audit will improve our capacity to provide long term care for HAE patients and their families. This article is protected by copyright. All rights reserved.

Etiology and predictors of cluster attacks of hereditary angioedema that recur despite pharmaceutical treatment

Introduction: Hereditary angioedema (HAE) is a disease that leads to recurrent swelling of the skin and mucous membranes, including the upper airway tract. Apart from being deadly, these attacks can be debilitating, which leads to a poor quality of life in patients. Clinicians are occasionally confronted with patients who have recurrent attacks despite treatment with C1 esterase inhibitor concentrate or β₂-receptor antagonists. The goal of this study was to investigate repeated attacks that occur 48 hours to 7 days ("cluster attacks") after treatment, to determine why they occur and the factors that may be associated with them, and thus to prevent their occurrence. Methods: We conducted a multicenter mixed retrospective-prospective study with data acquired from all documented attacks in our patients with collective (n = 132) between 2015 and 2018. Results: Eighty-five percent (n = 132) of our total patient collective (N = 156) agreed to participate in the study. Nine percent of these patients (n = 12) had cluster attacks, with a total of 48 cluster attacks. The data procured from the patients were mixed retrospective-prospective. Approximately 72% of all the cluster attacks were caused by exogenous stimuli (41% due to psychological stress, 29% due to physical stimuli, and 2% due to menstruation). Cluster attacks occurred in 7% of the patients who received prophylactic therapy in comparison with 12.5% of patients who received on-demand therapy. Cluster attacks comprised 48.4% of all the attacks that patients with cluster-attacks (n= 9) experienced. In addition, the patients who were underdosing their C1 esterase inhibitor treatment had cluster attacks more often. A lower "time to repeated attack" was seen in the patients who received on-demand therapy compared with those who received prophylactic therapy. Discussion: The percentage of the patients who had attacks as a result of exogenous triggers was higher in the cluster-attack group (70.5%) compared with the general HAE population (30-42%). Repeated attacks, therefore, were strongly associated with external triggers. The patients who received prophylactic treatment and who experienced cluster attacks were highly likely to have been underdosing, which may explain the repeated attacks despite treatment. In the patients prone to cluster attacks, prophylaxis should be considered.

Management of hereditary angioedema in Japan: Focus on icatibant for the treatment of acute attacks

Hereditary angioedema (HAE) is characterized by unpredictable, recurring and painful swelling episodes that can be disabling or even life-threatening. Awareness of HAE has progressively grown worldwide, and options for treatment of acute attacks and prevention of future attacks continue to expand; however, unmet needs in diagnosis and treatment remain. In Japan, recognition of HAE within the medical community remains low, and numerous obstacles complicate diagnosis and access to treatment. Importance of timely treatment of HAE attacks with on-demand therapies is continually demonstrated; recommended agents per the WAO/EAACI treatment guidelines published in 2018 include C1 inhibitor (C1-INH) concentrate, ecallantide, and icatibant. In Japan, multiple factors contribute to delayed HAE treatment (potentially leading to life-threatening consequences), including difficulties in finding facilities at which C1-INH agents are readily available. Recognition of challenges faced in Japan can help promote efforts to address current needs and expand access to effective therapies. Icatibant, a potent, selective bradykinin B₂ receptor antagonist, has demonstrated inhibition of various bradykinin-induced biological effects in preclinical studies and has shown efficacy in treating attacks in various clinical settings (e.g. clinical trials, real-world studies), and HAE patient populations (e.g. with C1-INH deficiency, normal C1-INH). Icatibant was approved in Japan for the treatment of HAE attacks in September 2018; its addition to the HAE treatment armamentarium contributes to improved patient care. In Japan, disease awareness and education campaigns are warranted to further advance the management of HAE patients in light of the unmet needs and the emerging availability of modern diagnostic approaches and therapies.

Hereditary angioedema in children and adolescents - A consensus update on therapeutic strategies for German-speaking countries

BACKGROUND/METHODS

At a consensus meeting in August 2018, pediatricians and dermatologists from German-speaking countries discussed the therapeutic strategy for the treatment of pediatric patients with type I and II hereditary angioedema due to C1 inhibitor deficiency (HAE-C1-INH) for Germany, Austria, and Switzerland, taking into account the current marketing approval status. HAE-C1-INH is a rare disease that usually presents during childhood or adolescence with intermittent episodes of potentially life-threatening angioedema. Diagnosis as early as possible and an optimal management of the disease are important to avoid ineffective therapies and to properly treat swelling attacks. This article provides recommendations for developing appropriate treatment strategies in the management of HAE-C1-INH in pediatric patients in German-speaking countries. An overview of available drugs in this age-group is provided, together with their approval status, and study results obtained in adults and pediatric patients.

RESULTS/CONCLUSION

Currently, plasma-derived C1 inhibitor concentrates have the broadest approval status and are considered the best available option for on-demand treatment of HAE-C1-INH attacks and for short- and long-term prophylaxis across all pediatric age-groups in German-speaking countries. For on-demand treatment of children aged 2 years and older, recombinant C1-INH and bradykinin-receptor antagonist icatibant are alternatives. For long-term prophylaxis in adolescents, the parenteral kallikrein inhibitor lanadelumab has recently been approved and can be recommended due to proven efficacy and safety.

Hereditary angioedema: On-demand treatment of angioedema attacks

The availability of effective acute treatment for angioedema has been fundamental in reducing the burden of illness for patients with hereditary angioedema (HAE). In building on the foundation of scientific advances that elucidate the pathomechanism(s) of attacks related to vascular permeability, novel targeted on-demand treatments have been developed and approved. These therapies have provided the means to arrest episodes of swelling, which, in the past, had the potential to inexorably lead to morbidity, and even mortality, for patients with HAE. Access to these medications, along with an emphasis on early administration and guidance that all attacks are candidates for treatment, has shifted the management paradigm for HAE. Although unmet needs remain, these acute therapies, coupled with advances in prophylactic treatment, have furthered the goal for all patients with HAE to live a normal life.

Population Pharmacokinetics and Exposure-Response Analyses to Guide Dosing of Icatibant in Pediatric Patients With Hereditary Angioedema

Elevated bradykinin levels are responsible for the development of clinical symptoms in patients with hereditary angioedema (HAE). Icatibant is a bradykinin type 2 receptor antagonist indicated for the acute treatment of HAE attacks. A population modeling and simulation approach was used to examine sources of variability impacting icatibant pharmacokinetics (PK) and provide guidance on icatibant dosing in pediatric patients with HAE. An exposure‐response analysis was performed for the time to onset of symptom relief (TOSR). Data from 141 adults (133 healthy, 8 with HAE) who received subcutaneous icatibant 30 mg and 31 pediatric patients with HAE who received 0.4 mg/kg (capped at 30 mg) were included in the analysis. Icatibant PK was described by a 2‐compartment model with linear elimination. Complete absorption of icatibant was expected within 1 hour of dosing. The apparent clearance and central volume of distribution were 15.4 L/h and 20.4 L, respectively. Icatibant PK was mainly dependent on body weight. The mean TOSR was very short (1.38 hours). A flat exposure‐response was observed, confirming that the relationship plateaued at the level of exposure observed in pediatric patients. Simulations confirmed that weight band–based dosing regimens (10 mg [12‐25 kg], 15 mg [26‐40 kg], 20 mg [41‐50 kg], 25 mg [51‐65 kg], and 30 mg [>65 kg]) resulted in exposure similar to the 0.4‐mg/kg dose. This analysis showed that icatibant undergoes rapid absorption, reaches levels required for therapeutic response, and promptly relieves HAE symptoms. A weight band–based dosing regimen is appropriate in pediatric patients with HAE.

US HAEA Medical Advisory Board 2020 Guidelines for the Management of Hereditary Angioedema

Scientific and clinical progress together with the development of effective novel therapeutic options has engendered multiple important changes in the diagnosis and management of hereditary angioedema (HAE). We now update and extend the 2013 United States Hereditary Angioedema Association Medical Advisory Board guidelines for the treatment and management of HAE. The guidelines are based on a comprehensive literature review with recommendations indicating both the strength of our recommendation and the quality of the underlying evidence. Guidelines are provided regarding the classification, diagnosis, on-demand treatment, prophylactic treatment, special considerations for women and children, development of a comprehensive management and monitoring plan, and assessment of burden of illness for both HAE due to C1 inhibitor deficiency and HAE with normal C1 inhibitor. Advances in HAE treatment now allow the development of management plans that can help many patients with HAE lead a normal life. Achieving this goal requires that physicians be familiar with the diagnostic and therapeutic transformations that have occurred in recent years.

In Vitro Pharmacological Profile of a New Small Molecule Bradykinin B2 Receptor Antagonist

We here report the discovery and early characterization of Compound 3, a representative of a novel class of small molecule bradykinin (BK) B₂ receptor antagonists, and its superior profile to the prior art B₂ receptor antagonists Compound 1 and Compound 2. Compound 3, Compound 2, and Compound 1 are highly potent antagonists of the human recombinant B₂ receptor (K_b values 0.24, 0.95, and 1.24 nM, respectively, calcium mobilization assay). Compound 3 is more potent than the prior art compounds and icatibant in this assay (K_b icatibant 2.81 nM). The compounds also potently inhibit BK-induced contraction of endogenous B₂ receptors in a human isolated umbilical vein bioassay. The potencies of Compound 3, Compound 2, Compound 1, and icatibant are (pA₂ values) 9.67, 9.02, 8.58, and 8.06 (i.e. 0.21, 0.95, 2.63, and 8.71 nM), respectively. Compound 3 and Compound 2 were further characterized. They inhibit BK-induced c-Fos signaling and internalization of recombinant human B₂ receptors in HEK293 cells, and do not antagonize the venous effects mediated by other G protein-coupled receptors in the umbilical vein model, including the bradykinin B₁ receptor. Antagonist potency of Compound 3 at cloned cynomolgus monkey, dog, rat, and mouse B₂ receptors revealed species selectivity, with a high antagonist potency for human and monkey B₂ receptors, but several hundred-fold lower potency for the other B₂ receptors. The in vitro off-target profile of Compound 3 demonstrates a high degree of selectivity over a wide range of molecular targets, including the bradykinin B₁ receptor. Compound 3 showed a lower intrinsic clearance in the microsomal stability assay than the prior art compounds. With an efflux ratio of 1.0 in the Caco-2 permeability assay Compound 3 is predicted to be not a substrate of efflux pumps. In conclusion, we discovered a novel chemical class of highly selective and very potent B₂ receptor antagonists, as exemplified by Compound 3. The compound showed excellent absorption in the Caco-2 assay, predictive of good oral bioavailability, and favourable metabolic stability in liver microsomes. Compound 3 has provided a significant stepping stone towards the discovery of the orally bioavailable B₂ antagonist PHA-022121, currently in phase 1 clinical development.

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 a genetic disease characterized by recurrent swelling episodes affecting the skin, gastrointestinal mucosa, and upper respiratory tract.

METHODS

A phase 3, single-arm, open-label study was performed to evaluate a selective bradykinin B₂ receptor antagonist, icatibant, for the treatment of acute attacks in Japanese patients with HAE Type I or II. After the onset of an acute attack, icatibant 30 mg was administered by the patient or a healthcare professional via subcutaneous injection in the abdomen.

RESULTS

Eight patients who had an attack affecting the skin (n = 4), abdomen (n = 3), or larynx (n = 1) were treated with icatibant (3 of the injections were self-administered). The median time to onset of symptom relief was 1.75 h (95% confidence interval, 1.00-2.50), and all patients had symptom relief within 5 h after administration. The time to maximum plasma concentration of icatibant was 1.79 h, and the maximum plasma concentration was 405 ng/ml. Seven patients experienced an injection site reaction, and 3 patients had adverse events (2 patients had a worsening or repeat HAE attack 29.0 and 18.3 h after icatibant administration, respectively, and 1 had headache).

CONCLUSIONS

Although the number of patients is small, the efficacy and tolerability of icatibant for acute attacks were demonstrated in Japanese patients with HAE, regardless of self-administration or administration by healthcare professional.

Modeling Cost-Effectiveness of On-Demand Treatment for Hereditary Angioedema Attacks

BACKGROUND

Hereditary angioedema (HAE) is a rare C1-inhibitor (C1-INH) deficiency disease. Low levels of functional C1-INH can lead to recurrent attacks of severe swelling occurring in areas such as the limbs, face, gastrointestinal tract, and throat. These attacks are both painful and disabling and, if not treated promptly and effectively, can result in hospitalization or death. Agents targeting the specific physiologic pathway of HAE attacks can offer improved outcomes with limited side effects compared with nonspecific therapies. However, these treatments display varying efficacy in HAE patients, including the need to redose or seek additional care if the treatment does not resolve symptoms effectively.

OBJECTIVE

To analyze the expected cost and utility per HAE attack when treated on-demand with HAE therapies indicated for the treatment of acute attacks.

METHODS

A decision-tree model was developed using TreeAge Pro software. Four on-demand HAE treatments were included: ecallantide, icatibant, plasma-derived (pd)C1-INH, and recombinant human (rh)C1-INH. The model uses probabilities for redosing, self-administration versus health care provider administration, and risk of hospitalization. Costs within the model consisted of the HAE treatments and associated health care system expenses. Nonattack baseline utility and attack utility were implemented for effectiveness calculations; time to attack resolution was considered as well. Effectiveness and overall costs per attack were calculated and used to estimate cost per quality-adjusted life-year (QALY). Variability and ranges in cost-effectiveness were determined using probabilistic sensitivity analyses. Finally, a budget impact model for a health plan with 1 million covered lives was also developed.

RESULTS

The base case model outputs show costs and calculated effectiveness per attack at $12,905 and 0.806 for rhC1-INH, $14,806 and 0.765 for icatibant, $14,668 and 0.769 for pdC1-INH, and $21,068 and 0.792 for ecallantide, respectively. Cost per QALY was calculated using 26.9 attacks per person-year, leading to results of $420,941 for rhC1-INH, $488,349 for icatibant, $483,892 for pdC1-INH, and $689,773 for ecallantide. Sensitivity analyses demonstrate that redose rates (from 3% for rhC1-INH to 44% for icatibant) are a primary driver of variability in cost-effectiveness. Annual health plan costs from the budget impact model are calculated as $6.94 million for rhC1-INH, $7.97 million for icatibant, $7.90 million for pdC1-INH, and $11.33 million for ecallantide.

CONCLUSIONS

Accounting for patient well-being and additional cost components of HAE attacks generates a better estimation of cost-effectiveness than drug cost alone. Results from this model indicate that rhC1-INH is the dominant treatment option with lower expected costs and higher calculated effectiveness than comparators. Further analyses reinforce the idea that low redose rates contribute to improved cost-effectiveness.

DISCLOSURES

Funding support was contributed by Pharming Healthcare. Relan and Adams are employed by Pharming Healthcare. Tyson and Magar are employed by AHRM, which received fees to perform the analysis and develop the manuscript. Bernstein reports grants, personal fees, and nonfinancial support from Shire, CSL Behring, and Pharming Healthcare; grants and personal fees from Biocryst; and nonfinancial support from HAEA, unrelated to this study.

Fresh frozen plasma for on-demand hereditary angioedema treatment in South Africa and Iran

Background

International guideline-recommended on-demand treatments for hereditary angioedema (HAE) include: C1-esterase inhibitor (plasma-derived or recombinant), or bradykinin-receptor antagonists. In most low- and middle-income countries (LMIC) these products are not registered or are unaffordable. Solvent-detergent, fresh or freeze-dried plasma therapy is thus the only available on-demand treatment in these settings; but published data on efficacy and safety are limited. This study evaluated the efficacy and safety of on-demand plasma treatment of acute HAE in two LMICs.

Methods

A retrospective folder or patient registry review of acute swelling episodes necessitating emergency room attendance amongst known HAE patients was conducted at treatment centers in South Africa and Iran. Data collected included the site of angioedema, timing and amount of fresh frozen plasma (FFP) administered, time-to-resolution, hospital length of stay and adverse events.

Results

There were 176 acute swelling episodes amongst 43 HAE patients; 98 were treated with FFP. The face, upper airway, and abdomen were involved in 15.3% (15/98), 53.1% (52/98) and 29.6% (29/98) of episodes treated with FFP respectively. Median (interquartile range ([IQR]) of FFP administered was 400 (280–560) mLs. In all episodes except two, FFP led to resolution, with median (IQR) hours to resolution 4 (2–12). Five transfusion reactions occurred, with one case of anaphylaxis and no deaths; giving an adverse reaction rate of 5%. Differences between South Africa and Iran included: (1) proportion of HAE type II(2) median (IQR) hours to FFP administration and hospitalization, (3) number of intubations after FFP infusion. Healthcare cost for FFP treatment was USD369- 791 in South Africa and USD275-550 in Iran, largely influenced by hospital length of stay.

Conclusions

Plasma (fresh-frozen) remains the only available effective on-demand treatment for acute HAE in many countries. FFP is effective and safe, but time-to-resolution is slower and adverse events are more frequent than published data on targeted therapies. Overall healthcare cost of FFP approaches that of targeted therapies – now available through global access programs – when hospitalization is prolonged.

Icatibant for the treatment of hereditary angioedema with C1-inhibitor deficiency in adolescents and in children aged over 2 years

INTRODUCTION

Hereditary angioedema (HAE) due to C1-inhibitor deficiency (C1-INH-HAE) is a rare disorder with life-threatening complications if untreated. It begins during childhood, and reduces the patient's quality of life. Therefore, the availability of an easily administered agent to relieve unpredictable HAE episodes is indispensable for this age group. Areas covered: Randomized, double-blind, placebo-controlled, open-label extensions and prospective observational studies have proven the safety and efficacy of the subcutaneously administered bradykinin B2 receptor antagonist, icatibant, in the acute treatment of HAE episodes in adult C1-INH-HAE patients. Recently, a Phase 3, multicenter, open-label, non-randomized, single-arm study demonstrated the efficacy, safety, and tolerability of icatibant as an acute treatment for pediatric patients aged 2 years to less than 18 years. Expert commentary: The clinical study in pediatric patients showed that icatibant undergoes rapid absorption, reaches a therapeutic level, and promptly relieves the symptoms. It is well tolerated, and the subcutaneous preparation, presented in a pre-filled syringe, ensures ease of use. It can be administered anytime, anywhere, and instantly - even by the patients themselves, or - in the case of children and adolescents - by a caregiver. Icatibant may greatly contribute to the improvement of the quality of life of pediatric patients.

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.

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.

The Icatibant Outcome Survey: experience of hereditary angioedema management from six European countries

BACKGROUND

Hereditary angioedema (HAE) due to C1-inhibitor deficiency (C1-INH-HAE) is a rare, potentially fatal, bradykinin-mediated disease. Icatibant is a bradykinin B2 receptor antagonist originally approved in 2008 in the European Union and 2011 in the United States as an acute therapy option for HAE attacks in adults.

OBJECTIVE

To compare demographics, disease characteristics and treatment outcomes of icatibant-treated HAE attacks in patients with C1-INH-HAE enrolled in the Icatibant Outcome Survey across six European countries: Austria, France, Germany, Italy, Spain and the UK.

METHODS

The Icatibant Outcome Survey [IOS; Shire, Zug, Switzerland (NCT01034969)] is an international observational study monitoring the safety and effectiveness of icatibant. Descriptive, retrospective analyses compared IOS country data derived during July 2009-April 2015.

RESULTS

Overall, 481 patients with C1-INH-HAE provided demographic data. A significant difference across countries in age at onset (P = 0.003) and baseline attack frequency (P < 0.001) was found although no significant differences were found with respect to gender (majority female; P = 0.109), age at diagnosis (P = 0.182) or delay in diagnosis (P = 0.059). Icatibant was used to treat 1893 attacks in 325 patients with majority self-administration in all countries. Overall, significant differences (all P < 0.001) were found across countries in time to treatment [median 1.8 h; median range: 0.0 (Germany-Austria) to 4.4 (France) h], time to resolution [median 6.5 h; median range: 3 (Germany-Austria) to 12 (France) h] and attack duration [median 10.5 h; median range: 3.1 (Germany-Austria) to 18.5 (France) h].

CONCLUSION

These data form the first European cross-country comparison of disease characteristics and icatibant use in patients with C1-INH-HAE who are enrolled in IOS. International variation in icatibant practice and treatment outcomes across the six European countries assessed highlight the need to further investigate the range of country-specific parameters driving regional variations in icatibant use.

Sustained response of recombinant human C1 esterase inhibitor for acute treatment of hereditary angioedema attacks

BACKGROUND

Symptoms of hereditary angioedema (HAE) attacks can recur soon after initial treatment; the durability of response for recombinant human C1 esterase inhibitor (rhC1INH) treatment is unknown.

OBJECTIVE

To examine the efficacy and durability of rhC1INH for acute HAE attacks.

METHODS

In this pooled post hoc analysis of 2 trials, patients with type I or II HAE (functional C1INH levels <50% of normal) and a baseline visual analog scale score of at least 50 mm were included if they had received at least 1 intravenous dose of 50 IU/kg of rhC1INH. Response was defined as symptom relief within 4 hours after treatment with persistence (≥20-mm decrease in visual analog scale scores [0 mm {"no symptoms at all"} to 100 mm {"extremely disabling"}] at 2 consecutive time points) during the 4 hours. Durability was the response without an increase of at least 20 mm in the minimum post-treatment visual analog scale score up to 24 hours. Recurrence and new attack symptoms were determined for patients with 72-hour post-treatment data.

RESULTS

Data were analyzed for 127 patients treated with 50 IU/kg of rhC1INH in 2 studies. Most attacks (90.7%) responded within 4 hours, with differences in response rates among attack locations (61.5%-94.4%). The median time to the beginning of symptom relief was 75.0 minutes (95% confidence interval 65.0-80.0). No relapse occurred during 24 hours for attacks that initially responded. Only 7.1% of attacks were associated with symptom recurrence within 72 hours of initial rhC1INH treatment.

CONCLUSION

This integrated analysis supports the efficacy of rhC1INH for treatment of acute HAE across multiple attacks, with a sustained response for at least 3 days.

TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT00225147 and NCT00262301.

Infections and edema

Infectious and inflammatory conditions of the head and neck may present with impaired airways. An understanding of the pathophysiology will allow for accurate diagnosis and prompt intervention. Preintervention discussion and planning by members of the airway team are crucial in developing a primary and backup plans for safely securing the airway.

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.

Icatibant for Multiple Hereditary Angioedema Attacks across the Controlled and Open-Label Extension Phases of FAST-3

BACKGROUND

In randomized, controlled, double-blind, multicenter phase 3 studies, one icatibant injection was efficacious and generally well tolerated in patients with a single hereditary angioedema (HAE) attack. Here, the efficacy and safety of icatibant for multiple HAE attacks was evaluated across the controlled and open-label extension phases of the For Angioedema Subcutaneous Treatment (FAST)-3 study (NCT00912093).

METHODS

In the controlled phase, adults with HAE type I or II were randomized (1:1) to receive a single subcutaneous injection of icatibant 30 mg or placebo within 6 h of an attack becoming mild (laryngeal) or moderate (cutaneous/abdominal). Open-label icatibant was administered for severe laryngeal symptoms. In the open-label extension phase, patients could receive up to three icatibant injections per attack. Efficacy and safety were analyzed for the first five icatibant-treated attacks at any location (prospective analysis) and laryngeal attacks (post hoc analysis) across both phases. Efficacy outcomes were based on patient-reported symptom severity (visual analog scale).

RESULTS

In groups of patients with one to five icatibant-treated attacks at any location (n = 88), the median times to onset of symptom relief, onset of primary symptom relief and almost complete symptom relief were 1.9-2.1, 1.5-2.0 and 3.5-19.7 h, respectively. The same outcomes for laryngeal attacks (n = 25) were 1.0-2.0, 1.0-2.0 and 1.5-8.1 h, respectively. The most frequently reported adverse events were a worsening or recurrence of HAE attack, headache and nasopharyngitis. Two serious adverse events (arrhythmia and noncardiac chest pain) were considered to be related to icatibant.

CONCLUSIONS

Icatibant was efficacious and generally well tolerated across multiple HAE attacks, including laryngeal attacks.

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.

Recombinant replacement therapy for hereditary angioedema due to C1 inhibitor deficiency

Hereditary angioedema is a rare genetic condition transmitted as an autosomal dominant trait and characterized most commonly by the production of either inadequate or nonfunctioning C1 esterase inhibitor (C1-INH), a blood protein that regulates proteases in the complement, fibrinolytic and contact systems. Patients with hereditary angioedema suffer from episodic, unpredictable manifestations of edema affecting multiple anatomical locations, including the GI tract, facial tissue, the upper airway, oropharynx, urogenital region and/or the arms and legs. A rational approach to treatment is replacement of C1-INH protein, to normalize the levels of C1-INH activity and halt the progression of the biochemical activation processes underlying the edema formation. Ruconest is a highly purified recombinant human C1-INH. This article will focus on the results of ten clinical studies demonstrating the efficacy and safety of Ruconest® (Pharming Group NV, Leiden, the Netherlands), which is now approved for use in Europe, Israel and the USA.