Oral Plasma Kallikrein Inhibitor for Prophylaxis in Hereditary Angioedema

Hereditary angioedema: current therapeutic management and future approaches

PURPOSE OF REVIEW

The aim of this review is to provide an account of the focus of therapeutic strategies for hereditary angioedema (HAE), give a brief overview of those used in the past and set aside and toughly discuss those currently available as first line. Further research is ongoing and the future therapeutic approaches that are still in different phases of study will be reviewed as well.

RECENT FINDINGS

In the last two decades, major research advancements on HAE pathophysiology and management were made and numerous novel therapeutic options are now available. Compared to the past, drugs available nowadays are more effective, well tolerated, and possibly have a more convenient administration route. Moreover, numerous other drugs with innovative mechanisms of action are under development.

SUMMARY

HAE is a rare genetic disease that if not promptly treated, it can lead to death from asphyxiation. Furthermore, due to its disfiguring and painful manifestations, HAE implies an important burden on the quality of life. Recently, following great research progresses on HAE therapy, evidence-based guidelines on HAE management were released. The therapeutic landscape of HAE is still under florid development, and it is possible novel treatments will remarkably revolutionize HAE management in the future.

Balancing efficacy and safety of complement inhibitors

Complement inhibitors have been approved for several immune-mediated diseases and they are considered the next paradigm-shifting approach in the treatment of glomerulonephritis. The hierarchical organization of the complement system offers numerous molecular targets for therapeutic intervention. However, complement is an integral element of host defense and therefore complement inhibition can be associated with serious infectious complications. Here we give a closer look to the hierarchical complement system and how interfering with proximal versus distal or selective versus unselective molecular targets could determine efficacy and safety. Furthermore, we propose to consider the type of disease, immunological activity, and patient immunocompetence when stratifying patients, e.g., proximal/unselective targets for highly active and potentially fatal diseases while distal and selective targets may suit more chronic disease conditions with low or moderate disease activity requiring persistent complement blockade in patients with concomitant immunodeficiency. Certainly, there exists substantial promise for anti-complement therapeutics. However, balancing efficacy and safety will be key to establish powerful treatment effects with minimal adverse events, especially when complement blockade is continued over longer periods of time in chronic disorders.

The Inhibition of Serine Proteases by Serpins Is Augmented by Negatively Charged Heparin: A Concise Review of Some Clinically Relevant Interactions

Serine proteases are members of a large family of hydrolytic enzymes in which a particular serine residue in the active site performs an essential role as a nucleophile, which is required for their proteolytic cleavage function. The array of functions performed by serine proteases is vast and includes, among others, the following: (i) the ability to fight infections; (ii) the activation of blood coagulation or blood clot lysis systems; (iii) the activation of digestive enzymes; and (iv) reproduction. Serine protease activity is highly regulated by multiple families of protease inhibitors, known collectively as the SERine Protease INhibitor (SERPIN). The serpins use a conformational change mechanism to inhibit proteases in an irreversible way. The unusual conformational change required for serpin function provides an elegant opportunity for allosteric regulation by the binding of cofactors, of which the most well-studied is heparin. The goal of this review is to discuss some of the clinically relevant serine protease-serpin interactions that may be enhanced by heparin or other negatively charged polysaccharides. The paired serine protease-serpin in the framework of heparin that we review includes the following: thrombin-antithrombin III, plasmin-anti-plasmin, C1 esterase/kallikrein-C1 esterase inhibitor, and furin/TMPRSS2 (serine protease Transmembrane Protease 2)-alpha-1-antitrypsin, with the latter in the context of COVID-19 and prostate cancer.

[Hereditary angioedema due to C1-inhibitor deficiency, a national disease management programme]

Hereditary angioedema (HAE) is a rare, painful, disabling and potentially fatal disease, where early diagnosis and effective treatment are critical. These Austrian guidelines for the diagnosis and management of HAE provide instructions and advice on the state of the art management of HAE in Austria in contrast to global guidelines, where the situation of all countries worldwide must be taken into account. Our goal is to help Austrian physicians to consider HAE as a differential diagnosis with corresponding symptoms, to make rational decisions for the diagnosis and management of HAE with C1-inhibitor deficiency (type 1 or type 2). The guidelines provide information on common and important clinical symptoms, diagnostic methods, treatment modalities, available HAE-specific medications in Austria and last but not least to motivate physicians to refer patients to HAE centers for confirmation of the diagnosis and adequate treatment decisions.

STAR-0215 is a Novel, Long-Acting Monoclonal Antibody Inhibitor of Plasma Kallikrein for the Potential Treatment of Hereditary Angioedema

Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by a deficiency in functional C1 esterase inhibitor, a serpin family protein that blocks the activity of plasma kallikrein. Insufficient inhibition of plasma kallikrein results in the overproduction of bradykinin, a vasoactive inflammatory mediator that produces both pain and unpredictable swelling during HAE attacks, with potentially life-threatening consequences. We describe the generation of STAR-0215, a humanized IgG1 antibody with a long circulating half-life (t1/2) that potently inhibits plasma kallikrein activity, with a >1000-fold lower affinity for prekallikrein and no measurable inhibitory activity against other serine proteases. The high specificity and inhibitory effect of STAR-0215 is demonstrated through a unique allosteric mechanism involving N-terminal catalytic domain binding, destabilization of the activation domain, and reversion of the active site to the inactive zymogen state. The YTE (M252Y/S254T/T256E) modified fragment crystallizable (Fc) domain of STAR-0215 enhances pH-dependent neonatal Fc receptor binding, resulting in a prolonged t1/2 in vivo (∼34 days in cynomolgus monkeys) compared with antibodies without this modification. A single subcutaneous dose of STAR-0215 (≥100 mg) was predicted to be active in patients for 3 months or longer, based on simulations using a minimal physiologically based pharmacokinetic model. These data indicate that STAR-0215, a highly potent and specific antibody against plasma kallikrein with extended t1/2, is a potential agent for long-term preventative HAE therapy administered every 3 months or less frequently. SIGNIFICANCE STATEMENT: STAR-0215 is a YTE-modified immunoglobulin G1 monoclonal antibody with a novel binding mechanism that specifically and potently inhibits the enzymatic activity of plasma kallikrein and prevents the generation of bradykinin. It has been designed to be a long-lasting prophylactic treatment to prevent attacks of HAE and to decrease the burden of disease and the burden of treatment for people with HAE.

Neurologic and Psychiatric Manifestations of Bradykinin-Mediated Angioedema: Old and New Challenges

Neurologic manifestations have been occasionally described in patients with bradykinin-mediated angioedema. The existing literature is currently limited to case series and case reports mainly described in the hereditary forms (HAE) concerning central nervous system (CNS) involvement. On the contrary, very little is known about peripheral and autonomic nervous system manifestations. CNS involvement in HAE may present with symptoms including severe headaches, visual disturbance, seizures, and various focal and generalized deficits. In addition, a stroke-like clinical picture may present in HAE patients. In turn, some drugs used in patients with cardiovascular and neurologic disorders, such as recombinant tissue plasminogen activator (r-tPA) and angiotensin-converting enzyme inhibitors (ACEI), may produce medication-induced angioedema, resulting in a diagnostic challenge. Finally, most patients with HAE have higher levels of psychological distress, anxiety, and depression. With this review, we aimed to provide an organized and detailed analysis of the existing literature on neurologic and psychiatric manifestations of HAE to shed light on these potentially invalidating symptoms and lay the foundation for further personalized diagnostic pathways for patients affected by this protean disease.

Content validation and psychometric evaluation of the Angioedema Quality of Life Questionnaire for hereditary angioedema

BACKGROUND

There is considerable burden of illness in hereditary angioedema (HAE). However, instruments to assess health-related quality of life (HRQoL) in HAE are limited. The Angioedema Quality of Life Questionnaire (AE-QoL) was developed to measure HRQoL in patients with recurrent angioedema; the validity of the AE-QoL in patients with HAE is described.

METHODS

To identify disease-related experiences with a focus on the impact of HAE on HRQoL, interviews were conducted with a group of clinician experts and patients with HAE from Canada, France, Germany, Spain, the United Kingdom, and the United States, along with a targeted literature review. Concepts were mapped to the AE-QoL to assess item relevance, interpretation, and conceptual coverage. Cognitive interviews assessed item clarity and relevance. A psychometric validation was performed using data from a phase 3 trial.

RESULTS

Interviews were conducted with seven clinicians and 40 adult patients. Patients reported 35 unique impacts of HAE on their lives, the most frequent being on work/school, social relationships, physical activities, and emotions, particularly fear/worrying and anxiety. Saturation for these impacts was reached, and all concepts covered in the AE-QoL were reported during the interviews. Patients agreed that the questionnaire items and response options were clear and relevant, and the 4-week recall period was appropriate. The psychometric validation included data from 64 patients. For AE-QoL total scores, excellent internal consistency (Cronbach's alpha > 0.90), test-retest reliability (intraclass coefficient > 0.80), convergent validity with the Sheehan Disability Scale (r = 0.663), divergent validity with the EQ-5D-5L index (r = 0.292) and EQ-VAS (r = 0.337), and known-groups validity (p < 0.0001; ɳ2 = 0.56) were demonstrated.

CONCLUSIONS

Qualitative and psychometric analyses showed that the AE-QoL is a reliable and valid instrument for measuring HRQoL in adult patients with HAE from six countries.

A narrative review of recent literature of the quality of life in hereditary angioedema patients

Hereditary angioedema (HAE) is a rare disorder that causes unpredictable and debilitating cutaneous and submucosal edema and can lead to death. HAE can impair patients' ability to perform daily activities, proportional to pain severity, with patients reporting lower productivity, missed time from work or school and potentially resulting in missed career and educational opportunities. Many patients with HAE experience a significant psychological burden, including anxiety and depression. Available treatment aims to prevent and/or treat HAE attacks as they occur, to reduce morbidity and mortality and, finally, to improve health-related quality of life. Two different validated specific angioedema instruments are available to assess patients' quality of life. The Angioedema Quality of Life Questionnaire (AE-QoL) examines diagnosed patients' quality of life but is not specific for HAE. The disease-specific questionnaire is the Hereditary Angioedema Quality of Life (HAE-QoL), and the first used for hereditary angioedema with C1 inhibitors (C1-INH) deficiency. These quality-of-life instruments are helpful to the HAE patients' assessment and to the development of better therapeutic strategies as clinical tools, as defined by international guidelines. Considering this context, this review was conducted to compare the effects of acute vs. long-term prophylaxis on HAE patients' health-related quality of life. In addition, the prevalence of anxiety and depression among these individuals was also reviewed.

Prevention of Recurrent Attacks of Hereditary Angioedema (HAE): Berotralstat and Its Oral Bioavailability

Hereditary angioedema (HAE) is a condition characterized by episodes of cutaneous and submucosal edema. Angioedema of the extremities and abdominal attacks are the most common manifestations of the disease. It can also affect the upper airways with the potential of becoming life-threatening. The two most common causes of HAE are a deficiency of C1 inhibitor (classified as type 1 HAE) or a dysfunction of C1 inhibitor (type 2 HAE). A malfunction or deficiency of C1 inhibitor leads to an overactivated plasma kallikrein (an inflammatory vasoactive peptide), that increases bradykinin, mediating the angioedema episodes in patients with HAE. To minimize the difficulties of this pathology and to improve patients' quality of life, prevention of this condition is essential. Berotralstat is a unique option for oral administration for routine prophylaxis. This drug acts by binding to kallikrein and reducing its plasma activity, lowering bradykinin levels. Open-label studies have demonstrated the effectiveness of a single daily dose of berotralstat 150 mg in preventing HAE attacks. This review aims to examine studies performed to elucidate the efficacy, safety, and tolerability of berotralstat.

Therapeutic monoclonal antibodies with a focus on hereditary angioedema

Monoclonal antibodies (mAbs) have been shown to be effective and generally safe across a continually expanding list of therapeutic areas. We describe the advantages and limitations of mAbs as a therapeutic option compared with small molecules. Specifically, we discuss a novel mAb in the treatment of hereditary angioedema (HAE), a rare and potentially life-threatening condition characterized by recurrent unpredictable swelling attacks. HAE is mediated by dysregulation of plasma kallikrein activity leading to overproduction of bradykinin. Current prophylactic treatment for HAE includes androgens or replacement of the endogenous plasma kallikrein inhibitor, C1 inhibitor. However, there remains an unmet need for an effective, less burdensome treatment option. Lanadelumab is a fully human mAb targeting plasma kallikrein. Results from clinical trials, including a pivotal Phase 3 study and its ensuing open-label extension study, demonstrated that lanadelumab is associated with few treatment-related adverse events and reduced the rate of HAE attacks. This novel treatment option has the potential to significantly improve the lives of patients with HAE.

Interventions for the long-term prevention of hereditary angioedema attacks

BACKGROUND

Hereditary angioedema (HAE) is a serious and potentially life-threatening condition that causes acute attacks of swelling, pain and reduced quality of life. People with Type I HAE (approximately 80% of all HAE cases) have insufficient amounts of C1 esterase inhibitor (C1-INH) protein; people with Type II HAE (approximately 20% of all cases) may have normal C1-INH concentrations, but, due to genetic mutations, these do not function properly. A few people, predominantly females, experience HAE despite having normal C1-INH levels and C1-INH function (rare Type III HAE). Several new drugs have been developed to treat acute attacks and prevent recurrence of attacks. There is currently no systematic review and meta-analysis that included all preventive medications for HAE.

OBJECTIVES

To assess the benefits and harms of interventions for the long-term prevention of HAE attacks in people with Type I, Type II or Type III HAE.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 3 August 2021.

SELECTION CRITERIA

We included randomised controlled trials in children or adults with HAE that used medications to prevent HAE attacks. The comparators could be placebo or active comparator, or both; approved and experimental drug trials were eligible for inclusion. There were no restrictions on dose, frequency or intensity of treatment. The minimum length of four weeks of treatment was required for inclusion; this criterion excluded the acute treatment of HAE attacks.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. HAE attacks (number of attacks per person, per population) and change in number of HAE attacks; 2. mortality and 3. serious adverse events (e.g. hepatic dysfunction, hepatic toxicity and deleterious changes in blood tests). Our secondary outcomes were 4. quality of life; 5. severity of breakthrough attacks; 6. disability and 7. adverse events (e.g. weight gain, mild psychological changes and body hair). We used GRADE to assess certainty of evidence for each outcome.

MAIN RESULTS

We identified 15 studies (912 participants) that met the inclusion criteria. The studies included people with Type I and II HAE. The studies investigated avoralstat, berotralstat, subcutaneous C1-INH, plasma-derived C1-INH, nanofiltered C1-INH, recombinant human C1-INH, danazol, and lanadelumab for the prevention of HAE attacks. We did not find any studies on the use of tranexamic acid for prevention of HAE attacks. All drugs except avoralstat reduced the number of HAE attacks compared with placebo. For breakthrough attacks that occurred despite prophylactic treatment, intravenous and subcutaneous forms of C1-INH and lanadelumab reduced attack severity. It is not known whether other drugs have a similar effect, as the severity of breakthrough attacks in people taking drugs other than C1-INH and lanadelumab was not reported. For quality of life, avoralstat, berotralstat, C1-INH (all forms) and lanadelumab increased quality of life compared with placebo; there were no data for danazol. Four studies reported on changes in disability during treatment with C1-INH, berotralstat and lanadelumab; all three drugs decreased disability compared with placebo. Adverse events, including serious adverse events, did not occur at a rate higher than placebo. However, serious adverse event data and other adverse event data were not available for danazol, which prevented us from drawing conclusions about the absolute or relative safety of this drug. No deaths were reported in the included studies. The analysis was limited by the small number of studies, the small number of participants in each study and the lack of data on older drugs, therefore the certainty of the evidence is low. Given the rarity of HAE, it is not surprising that drugs were rarely directly compared, which does not allow conclusions on the comparative efficacy of the various drugs for people with HAE. Finally, we did not identify any studies that included people with Type III HAE. Therefore, we cannot draw any conclusions about the efficacy or safety of any drug in people with this form of HAE.

AUTHORS' CONCLUSIONS

The available data suggest that berotralstat, C1-INH (subcutaneous, plasma-derived, nanofiltered and recombinant), danazol and lanadelumab are effective in lowering the risk or incidence (or both) of HAE attacks. In addition, C1-INH and lanadelumab decrease the severity of breakthrough attacks (data for other drugs were not available). Avoralstat, berotralstat, C1-INH (all forms) and lanadelumab increase quality of life and do not increase the risk of adverse events, including serious adverse events. It is possible that danazol, subcutaneous C1-INH and recombinant human C1-INH are more effective than berotralstat and lanadelumab in reducing the risk of breakthrough attacks, but the small number of studies and the small size of the studies means that the certainty of the evidence is low. This and the lack of head-to-head trials prevented us from drawing firm conclusions on the relative efficacy of the drugs.

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.

Time Trade-Off Utilities for Hereditary Angioedema Health and Caregiver States

BACKGROUND

Hereditary angioedema (HAE) is an inherited chronic rare disease characterised by recurrent swelling attacks that are associated with significant physical and psychological burden. There is limited understanding of the effect of attack location on this burden and of caregiver burden.

OBJECTIVE

Our objective was to capture the relative burden of HAE health and caregiver states, including different attack locations, through a time trade-off (TTO) analysis involving participants from the general public.

METHODS

Qualitative interviews were undertaken to inform vignette development for the TTO study, including vignettes for abdominal, facial, hand and laryngeal attack health states, and an attack-free and caregiver state. Members of the general public in England rated vignettes in TTO interviews, which included a visual analogue scale (VAS) component. For the development of the health state vignettes, qualitative interviews with 15 patients, 5 caregivers and 1 clinical expert were performed. TTO analysis was based on vignette valuation completed by 100 members of the general public.

RESULTS

The TTO values were as follows: attack-free, 0.783 (standard deviation [SD] 0.316); hand: 0.582 (SD 0.380); facial: 0.483 (SD 0.448); abdominal: 0.345 (SD 0.458); and laryngeal: 0.128 (SD 0.529). The caregiver rating was 0.762 (SD 0.303). V' scores were similar and consistent with TTO values.

CONCLUSION

TTO utility values demonstrate that HAE places a significant burden on patients, which is influenced by attack location, and on caregivers. These utility weights can provide important information on quality of life for future economic evaluations of treatments.

Population pharmacokinetic modeling and simulations of berotralstat for prophylactic treatment of attacks of hereditary angioedema

Hereditary angioedema (HAE) is an autosomal dominant disorder characterized by recurrent episodes of swelling of the skin, larynx, gastrointestinal tract, genitals, and extremities that can be disruptive to patient quality of life. Dysregulation of plasma kallikrein activity leads to increased production and accumulation of bradykinin in HAE and causes attacks of angioedema. Plasma kallikrein is a serine protease essential for the formation of bradykinin. Berotralstat is a potent, highly selective, orally bioavailable small‐molecule plasma kallikrein inhibitor that has been approved to prevent attacks of HAE in adults and children 12 years of age and older. Population pharmacokinetic (PK) analyses were conducted to describe the PK of berotralstat (BCX7353; Orladeyo^™) and to evaluate the covariates that may explain variability in PK. The PK of berotralstat were characterized by population PK modeling of data from 13 clinical studies and a total of 771 healthy subjects and patients with HAE. The PK profile was well described by a three‐compartment model with first‐order absorption including an absorption lag time and linear elimination. Among the covariates tested, the effects of bilirubin and food were found not to be clinically significant and were removed from the model. Covariate analysis indicated significant effects of dose on bioavailability and weight on berotralstat clearance and volume. Despite the covariate effect of weight, simulations in adolescents and adults who were underweight, low weight, and overweight demonstrated similar predicted exposures to those observed at therapeutic doses in a clinical trial. Therefore, no dose adjustment is required in these HAE patient subpopulations.

Attenuated androgen discontinuation in patients with hereditary angioedema: a commented case series

Background

Hereditary angioedema (HAE) is characterized by potentially severe and life-threatening attacks of localized swelling. Prophylactic therapies are available, including attenuated androgens. Efficacy of attenuated androgens has not been assessed in large, randomized, placebo-controlled trials and can be associated with frequent, and sometimes severe, side effects. As better tolerated targeted therapies become available, attenuated androgen withdrawal is increasingly considered by physicians and their patients with HAE. Attenuated androgens withdrawal has not been systematically studied in HAE, although examination of other disorders indicates that attenuated androgen withdrawal may result in mood disturbances and flu-like symptoms. Standardized protocols for attenuated androgen discontinuation that continue to provide control of attacks while limiting potential attenuated androgen withdrawal symptoms are not established as the outcomes of different withdrawal strategies have not been compared. We aim to describe the challenges of attenuated androgen discontinuation in patients with HAE and how these may continue into the post-androgen period.

Case presentation

We present a retrospective case series of 10 patients with confirmed type I HAE who have discontinued prophylactic treatment with attenuated androgens. The most common reason for attenuated androgen discontinuation was side effects. Attenuated androgens were either immediately withdrawn, tapered and/or overlapped with another treatment. The major challenge of discontinuation was the management of an increased frequency and severity of HAE attacks in some patients.

Conclusions

Healthcare teams need to undertake careful planning and monitoring after attenuated androgens discontinuation, and modify treatment strategies if HAE control is destabilized with an increased number of attacks. Discontinuation of attenuated androgens is definitively an option in an evolving HAE treatment landscape, and outcomes can be favourable with additional patient support and education.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-021-00644-0.

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.

Guidelines for management of hereditary angioedema: What is new? What is missing?

Background: Hereditary angioedema is an autosomal dominant disease that presents with recurrent episodic swelling of the submucosal and/or subcutaneous tissues of the cutaneous, gastrointestinal, and respiratory systems. Evaluation and treatment guidelines have been published nationally and internationally to aid the treating provider. Methods: A review of the most cited and most recent updated guidelines was undertaken to review key points and to explore real-world feasibility of incorporating them into clinical practice. The International World Allergy Organization/European Academy of Allergy and Clinical Immunology (WAO/EAACI) Guideline for the Management of Angioedema - The 2017 Revision and Update, and the consensus reports from the Hereditary Angioedema International Working Group, the Joint Task Force on Practice Parameters focused practice parameter update, and the most recently updated US HAEA Medical Advisory Board 2020 Guidelines for the Management of Hereditary Angioedema were reviewed and summarized. Results: Key points that have been consistent throughout the guidelines include recommendations for evaluation and classification of hereditary angioedema as well as evidence-based guidelines for treatment. Further attention is required on the evaluation and continuous assessment of the burden of illness and quality of life (QoL). Conclusion: The guidelines for management of hereditary angioedema provide a framework for the clinician. However, the physician-patient dialog with regard to the patient disease experience, which includes attack frequency, severity, and Qol, must be continually assessed.

Phase 1 Dose-Escalation Study of Plasma Kallikrein Inhibitor THR-149 for the Treatment of Diabetic Macular Edema

Purpose

The purpose of this study was to evaluate the safety and preliminary efficacy of a single intravitreal injection of 3 dose levels of THR-149 in adults with center-involved diabetic macular edema (DME).

Methods

A phase 1, open-label, multicenter 3 + 3 dose-esclation study with 3-month follow-up. The primary endpoint was the incidence of dose-limiting toxicities (DLTs) up to and including the Day 14 visit. Additional key endpoints included the incidence of (serious) adverse events ([S]AEs), mean change from baseline in best-corrected visual acuity (BCVA) and central subfield thickness (CST), and additional imaging parameters on widefield fluorescein angiography and optical coherence tomography (OCT) angiography.

Results

Twelve subjects were treated: 3 subjects received THR-149 0.005 mg, 3 received 0.022 mg and 6 received 0.13 mg. Baseline ocular characteristics were balanced between subjects at each dose level. There were no DLTs or ocular SAEs, and all subjects completed the study. Six subjects experienced a total of 10 AEs in the study eye; 1 case of mild anterior chamber inflammation was deemed related to THR-149 and/or the injection procedure. Mean change from Baseline in BCVA was +7.5 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters on Day 14, and +6.4 ETDRS letters by Month 3. CST was variable, and mean CST change from baseline was +30.0 µm at Month 3. There were no clinically meaningful changes in imaging parameters.

Conclusions

THR-149 was safe and well tolerated; preliminary efficacy in terms of BCVA improvement was observed.

Translational Relevance

This work bridges the gap between basic research and clinical care by providing first in human safety and preliminary efficacy data, supporting the further investigation of THR-149 as a potential treatment for DME.

Subclinical Signs of Retinal Involvement in Hereditary Angioedema

To explore retinal abnormalities using spectral domain optical coherence tomography (SD-OCT) and OCT-angiography (OCT-A) in a highly selective cohort of patients with type I hereditary angioedema (HAE). This prospective case-control study included 40 type I HAE patients and 40 age-/sex-matched healthy subjects (HC). All participants underwent SD-OCT-scanning of retinal posterior pole (PP), peripapillary retinal nerve fiber layer (pRNFL), and optic nerve head (ONH). Superficial/deep capillary density was analyzed by OCT-A. A total of 80 eyes from 40 HAE and 40 eyes from HC were evaluated. The pRNFL was thicker in HAE than in HC in nasal superior (p < 0.0001) and temporal quadrants (p = 0.0005 left, p = 0.003 right). The ONH thickness in HAE patients was greater than in HC in the nasal (p = 0.008 left, p = 0.01 right), temporal (p = 0.0005 left, p = 0.003 right), temporal inferior (p = 0.007 left, p = 0.0008 right), and global (p = 0.005 left, p = 0.007 right) scans. Compared to HC, HAE showed a lower capillary density in both superficial (p = 0.001 left, p = 0.006 right) and deep (p = 0.008 left, p = 0.004 right) whole images, and superficial (p = 0.03 left) and deep parafoveal (p = 0.007 left, p = 0.005 right) areas. Our findings documented subclinical retinal abnormalities in type I HAE, supporting a potential role of the retinal assessment by SD-OCT/OCT-A as a useful tool in the comprehensive care of HAE patients.

Crosstalk between the renin-angiotensin, complement and kallikrein-kinin systems in inflammation

During severe inflammatory and infectious diseases, various mediators modulate the equilibrium of vascular tone, inflammation, coagulation and thrombosis. This Review describes the interactive roles of the renin–angiotensin system, the complement system, and the closely linked kallikrein–kinin and contact systems in cell biological functions such as vascular tone and leakage, inflammation, chemotaxis, thrombosis and cell proliferation. Specific attention is given to the role of these systems in systemic inflammation in the vasculature and tissues during hereditary angioedema, cardiovascular and renal glomerular disease, vasculitides and COVID-19. Moreover, we discuss the therapeutic implications of these complex interactions, given that modulation of one system may affect the other systems, with beneficial or deleterious consequences.

The renin–angiotensin, complement and kallikrein–kinin systems comprise a multitude of mediators that modulate physiological responses during inflammatory and infectious diseases. This Review investigates the complex interactions between these systems and how these are dysregulated in various conditions, including cardiovascular diseases and COVID-19, as well as their therapeutic implications.

[Pharmacological and clinical study results of Berotralstat Hydrochloride for long-term prophylactic treatment of hereditary angioedema]

Hereditary angioedema (HAE) is a rare disease that causes serious health problem and affects on quality of life for patient due to recurrent episodes of angioedema in various body such as the skin, larynx, digestive tract, and limbs. Many HAE patients have deficiency or dysfunction of C1 inhibitor, impaired regulation of plasma kallikrein activity and overproduction of bradykinin, resulting in leading to episodes of increased capillary hyper permeability and angioedema. Therapy of HAE consists of on-demand treatment for acute attack and prophylactic treatment by suppressing the onset of acute attack in the short and long term. However, no drug has been approved for long-term prophylaxis in Japan. Berotralstat hydrochloride (ORLADEYO Capsules 150 mg) is an oral, selective plasma kallikrein inhibitor approved for the suppression of the onset of acute attacks in HAE in Japan in January 2021. Preclinical studies demonstrated that Berotralstat is a potent and highly specific inhibitor of human plasma kallikrein activity. Berotralstat suppressed bradykinin production in the HUVEC system. Clinical studies demonstrated that oral administration of Berotralstat to HAE type I or type II patients at a dose of 150 mg once daily showed a reduction of HAE attack rate and clinically significant change in angioedema quality of life score. The most common side effect was gastrointestinal symptoms. In conclusion, preclinical and clinical data indicated that Berotralstat is an effective treatment for long-term prophylactic treatment by suppressing the onset of acute attack in HAE patient and is considered to be a useful treatment option for patients.

Berotralstat (BCX7353): Structure-Guided Design of a Potent, Selective, and Oral Plasma Kallikrein Inhibitor to Prevent Attacks of Hereditary Angioedema (HAE)

Hereditary angioedema (HAE) is a rare and potentially life-threatening disease that affects an estimated 1 in 50 000 individuals worldwide. Until recently, prophylactic HAE treatment options were limited to injectables, a burdensome administration route that has driven the need for an oral treatment. A substantial body of evidence has shown that potent and selective plasma kallikrein inhibitors that block the generation of bradykinin represent a promising approach for the treatment of HAE. Berotralstat (BCX7353, discovered by BioCryst Pharmaceuticals using a structure-guided drug design strategy) is a synthetic plasma kallikrein inhibitor that is potent and highly selective over other structurally related serine proteases. This once-daily, small-molecule drug is the first orally bioavailable prophylactic treatment for HAE attacks, having successfully completed a Phase III clinical trial (meeting its primary end point) and recently receiving the U.S. Food and Drug Administration's approval for the prophylactic treatment of HAE attacks in patients 12 years and older.

Berotralstat (BCX7353) is a novel oral prophylactic treatment for hereditary angioedema: Review of phase II and III studies

Background: Hereditary angioedema (HAE) is a rare genetic disorder characterized by unpredictable and potentially life-threatening episodes of swelling in various parts of the body. These attacks can be painful and debilitating, and affect a patient's quality of life. Every patient who experiences an attack should be treated with on-demand medication to mitigate attack severity and duration. Many patients with HAE also receive long-term prophylaxis to reduce the frequency and severity of edema episodes. Although long-term prophylaxis reduces the disease burden for patients with HAE, available intravenous and subcutaneous treatments are accompanied by a significant treatment burden because of the logistical, emotional, and physical challenges posed by their long-term parenteral nature. Androgens are an effective oral prophylactic treatment; however, they are associated with significant adverse events and are not suitable for all patients. Thus, the HAE community has expressed interest in the development of alternative oral prophylactic therapies for preventing HAE attacks. Objective: Here, we review the phase II and III clinical data of berotralstat (BCX7353), which was approved by the U.S. Food and Drug Administration in December 2020. Results: Berotralstat is an oral, second-generation, synthetic, small-molecule plasma kallikrein inhibitor taken once daily for the prevention of HAE attacks in patients ages ≥ 12 years. Results from the APeX studies (APeX-1 NCT02870972, APeX-2 NCT03485911, APeX-S NCT03472040, APex-J NCT03873116) demonstrated the efficacy of berotralstat as long-term prophylaxis for patients with HAE, which showed a reduction in the attack rate and on-demand medication usage. Berotralstat was well tolerated, and gastrointestinal treatment-emergent adverse events were generally mild and self-limited. Conclusion: Oral berotralstat is an effective and safe long-term prophylactic treatment for patients with HAE that will provide patients unable to tolerate parenteral therapies with the option of disease control. Berotralstat may be associated with reduced treatment burden compared with injectable therapies, highlighting the importance of patient preference with regard to the administration route of their HAE prophylactic treatment.

How to Measure Disease Activity, Impact, and Control in Patients with Recurrent Wheals, Angioedema, or Both

Chronic spontaneous urticaria and chronic inducible urticaria are characterized by wheals, angioedema, or both, whereas other conditions such as hereditary angioedema present only with angioedema. The unpredictability of outbreaks, disfigurement, pruritus, and associated sleep and work disturbance can cause a significant impact on quality of life (QoL). Significant breakthroughs in the understanding of these conditions in recent years have led to the development of novel therapies. Assessment of patients with these conditions not only focuses on the clinical activity of the condition, but also on the impact on QoL and disease control with treatment. Patient-reported outcome measures, especially if sufficiently validated, give due prominence to the patient's perspective regarding disease impact and treatment outcomes. This article will review the tools readily available to assess activity, impact, and control in patients with recurrent wheals, angioedema, or both.

What's New in the Treatment of Urticaria and Angioedema

Chronic urticaria and angioedema are diseases often managed by Allergy and Immunology specialists. Recent international guidelines have outlined a stepwise approach to management of patients using dose escalation of second-generation antihistamines followed by use of omalizumab and finally cyclosporine in more refractory cases. In select patients (those with refractory chronic urticaria), nonbiologic alternative medications with anti-inflammatory or immunosuppressant activity may be considered. Angioedema without wheals may have several different pathophysiologic mechanisms. Optimal management of mast cell-mediated angioedema is less clear but is often managed similar to chronic spontaneous urticaria. Drug-induced angioedema due to angiotensin-converting enzyme inhibitors is a common cause of angioedema in the emergency department. Although bradykinin is thought to be a primary mediator for this type of angioedema, studies of targeted therapies have been generally disappointing. In contrast, several targeted therapies have been proven successful using acute and preventive approaches for management of hereditary angioedema. Further developments, including novel biologics, novel oral therapies, and gene therapy approaches, may hopefully continue to broaden therapeutic options to ensure optimal individual management of patients with hereditary angioedema.

Clinical manifestations of hereditary angioedema and a systematic review of treatment options

OBJECTIVE

This study systematically reviews the existing literature on the management of hereditary angioedema (HAE) and provides an update on the clinical presentation and specific therapies.

METHODS

A literature search of PubMed and Embase databases was conducted from start of the database to February 2021. Inclusion criteria included relevant systematic reviews, randomized control clinical trials, prospective and retrospective cohort studies, and outcomes research published in English and available in full-text. Out of 310 candidate articles, a total of 55 articles were included in our study.

RESULTS

The most common genetic form of HAE in up to 85% of cases is caused by low levels of C1 esterase inhibitor (C1-INH) protein, leading to a bradykinin-mediated increase in vascular permeability. During an attack of HAE, abortive treatment with C1-INH replacement is most commonly described, however, icatibant, ecallantide, or fresh frozen plasma are also used. Long-term prophylaxis in the form of C1-INH replacement (subcutaneous or intravenous), monoclonal antibodies targeting plasma kallikrein, attenuated androgens, and transexemic acid should be considered for those who suffer from frequent, severe attacks.

CONCLUSION

Progressively distal involvement of the upper airway, especially the larynx, has been shown to pose an increased risk of asphyxiation and death in the acute presentation of HAE. Evaluation by an otolaryngologist is often sought during the emergent clinical management of HAE; therefore, it is prudent that the consulting physician is well-versed in the prompt recognition, triage of patients, and appropriate treatment modalities.

LEVEL OF EVIDENCE

1A.

Oral berotralstat for the prophylaxis of hereditary angioedema attacks in patients in Japan: A phase 3 randomized trial

Background

With no approved treatments in Japan for the prevention of hereditary angioedema (HAE) attacks, there is a significant unmet need for long‐term prophylactic therapies for Japanese patients with HAE. Berotralstat (BCX7353) is an oral, once‐daily, highly selective inhibitor of plasma kallikrein in development for prophylaxis of angioedema attacks in HAE patients.

Methods

APeX‐J is a phase 3, randomized, double‐blind, placebo‐controlled, parallel‐group, 3‐part trial conducted in Japan (University Hospital Medical Information Network identifier, UMIN000034869; ClinicalTrials.gov identifier, NCT03873116). Patients with a clinical diagnosis of type 1 or 2 HAE underwent a prospective run‐in period of 56 days to determine eligibility, allowing enrollment of those with ≥2 expert‐confirmed angioedema attacks. Patients were randomly assigned (1:1:1) and stratified by baseline attack rate (≥2 vs. <2 expert‐confirmed attacks/month between screening and randomization) to receive once‐daily berotralstat 110 mg, berotralstat 150 mg, or placebo. The primary endpoint was the rate of expert‐confirmed angioedema attacks during dosing in the 24‐week treatment period.

Results

Nineteen patients were randomized to receive once‐daily berotralstat 110 mg (n = 6), berotralstat 150 mg (n = 7), or placebo (n = 6). Treatment with berotralstat 150 mg significantly reduced HAE attacks relative to placebo (1.11 vs. 2.18 attacks/month, p = .003). The most frequently reported treatment‐emergent adverse events (TEAEs) in berotralstat‐treated patients (n = 13) were nasopharyngitis (n = 4, 31%), abdominal pain, cough, diarrhea, and pyrexia (n = 2 each, 15%).

Conclusions

Orally administered, once‐daily berotralstat 150 mg significantly reduced the frequency of HAE attacks and was safe and well tolerated, supporting its use as a prophylactic therapy in patients with type 1 or 2 HAE in Japan.

Randomized Trial of the Efficacy and Safety of Berotralstat (BCX7353) as an Oral Prophylactic Therapy for Hereditary Angioedema: Results of APeX-2 Through 48 Weeks (Part 2)

BACKGROUND

Berotralstat (BCX7353) is a recently approved, oral, once-daily kallikrein inhibitor for hereditary angioedema (HAE) prophylaxis. In the APeX-2 trial, berotralstat reduced HAE attack rates over 24 weeks, with a favorable safety and tolerability profile.

OBJECTIVE

Evaluate berotralstat safety, tolerability, and effectiveness over 48 weeks.

METHODS

APeX-2 is a phase 3, parallel-group, multicenter trial (NCT03485911) in patients with HAE due to C1 esterase inhibitor deficiency. Part 1 was double-blind and placebo-controlled, with patients randomized to 24 weeks of berotralstat 150 mg, 110 mg, or placebo. In part 2, patients continued berotralstat the same dose or, if initially randomized to placebo, were rerandomized to berotralstat 150 mg or 110 mg through weeks 24 to 48. The primary end point was safety and tolerability.

RESULTS

One hundred eight patients received 1 or more doses of berotralstat in part 2. Treatment-emergent adverse events (TEAEs) occurred in 30 of 39 patients (77%) in the placebo group during part 1, and 25 of 34 patients (74%) re-randomized from placebo to berotralstat 110 mg or 150 mg in part 2, with drug-related TEAEs in 13 of 39 (33%), and 11 of 34 (32%) in the same groups. Most TEAEs were mild or moderate, with no serious drug-related TEAEs. The most common TEAEs were upper respiratory tract infections, abdominal pain, diarrhea, and vomiting. Mean (±standard error of the mean) monthly attack rates at baseline and week 48 were 3.06 (±0.25) and 1.06 (±0.25) in the berotralstat 150mg 48-week group and 2.97 (±0.21) and 1.35 (±0.33) in the berotralstat 110mg 48-week group.

CONCLUSIONS

The safety, tolerability, and effectiveness of berotralstat were maintained over 48 weeks of treatment.

The role of innate immunity in myasthenia gravis

Myasthenia gravis (MG) is a T cell-driven, B cell-mediated and autoantibody-dependent autoimmune disorder against neuromuscular junctions (NMJ). Accumulated evidence has emerged regarding the role of innate immunity in the pathogenesis of MG. In this review, we proposed two hypothesis underlying the pathological mechanism. In the context of gene predisposition, on the one hand, Toll-like receptors (TLRs) pathways were initiated by viral infection in the thymus with MG to generate chemokines and pro-inflammatory cytokines such as Type I interferon (IFN), which facilitate the thymus to function as a tertiary lymphoid organ (TLO). On the another hand, the antibodies against acetylcholine receptors (AChR) generated by thymus then activated the classical pathways on thymus and neuromuscular junction (NMJ). Futher, we also highlight the role of innate immune cells in the pathogenic response. Finally, we provide some future perspectives in developing new therapeutic approaches particularly targeting the innate immunity for MG.

Berotralstat: First Approval

Berotralstat (ORLADEYO™) is an orally administered kallikrein inhibitor, which has been developed by BioCryst Pharmaceuticals for hereditary angioedema (HAE). The inhibition of kallikrein by berotralstat decreases the production of bradykinin, which prevents the localised tissue oedema that occurs during attacks of HAE. Berotralstat has been approved in the USA, and subsequently in Japan, for prophylaxis to prevent attacks of HAE in adults and paediatric patients aged 12 years or older. This article summarises the milestones in the development of berotralstat leading to this first approval for prophylaxis to prevent attacks of HAE.

Proteolytic activity of contact factor zymogens

Contact activation is triggered when blood is exposed to compounds or "surfaces" that promote conversion of the plasma zymogens factor XII (FXII) and prekallikrein to the active proteases FXIIa and kallikrein. FXIIa promotes blood coagulation by converting zymogen factor XI (FXI) to the protease FXIa. Contact activation appears to represent an enhancement of the propensity for FXII and prekallikrein to reciprocally activate each other by surface-independent limited proteolysis. The nature of the activities that perpetuate this process, and that trigger contact activation, are debated. FXII and prekallikrein, like most members of the chymotrypsin/trypsin protease family, are synthesized as single polypeptides that are presumed to be in an inactive state. Internal cleavage leads to conformational changes in the protease domain that convert the enzyme active site from a closed conformation to an open conformation accessible to substrates. We observed that FXII expresses a low level of activity as a single-chain zymogen that catalyzes prekallikrein activation in solution, as well as surface-dependent activation of prekallikrein, FXI, and FXII (autoactivation). Prekallikrein also expresses activity that promotes cleavage of kininogen to release bradykinin, and surface-dependent FXII activation. Modeling suggests that a glutamine residue at position 156 in the FXII and prekallikrein protease domains stabilizes an open active site conformation by forming hydrogen bonds with Asp194. The activity inherent in FXII and prekallikrein suggests a mechanism for sustaining reciprocal activation of the proteins and for initiating contact activation, and supports the premise that zymogens of some trypsin-like enzymes are active proteases.

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: Epidemiology and burden of disease

<title/> Hereditary angioedema (HAE) is a rare autosomal dominant genetic disorder characterized by swelling of subcutaneous, mucosal, and submucosal tissue without associated pruritus or wheals caused by a temporary localized increase in vascular permeability. Swelling attacks primarily affect the cutaneous tissue, abdominal viscera, genitals, or airways. <title/> Reports of the prevalence of HAE C1 inhibitor (C1-INH) deficiency varies widely, from 1:50,000 to 1:100,000. The prevalence of HAE normal C1-INH is unknown but is likely much lower than HAE C1-INH. Approximately one-third of patients with recurrent angioedema without wheals have HAE. <title/> The burden of disease for patients with HAE is substantial. Attacks are unpredictable with respect to frequency, severity, and the site that swells. Laryngeal attacks can be fatal if not treated promptly and appropriately. Feelings of stress, anxiety, and depression can trigger attacks, and begin a cycle of attacks that cause anxiety that, in turn, triggers further attacks. Despite full physical recovery between attacks, patients often experience continual emotional impairment and reduced quality of life (QoL). Absenteeism from work and presenteeism at work or educational activities for patients and caregivers increase stress and reduce productivity during and between attacks. Missed opportunities for career development are common. <title/> Significant advances have been made in the past decade to expand both acute and prophylactic treatment options for patients with HAE, lowering both the disease and treatment burden, and improving the QoL of patients with HAE.

Oral once-daily berotralstat for the prevention of hereditary angioedema attacks: A randomized, double-blind, placebo-controlled phase 3 trial

BACKGROUND

Berotralstat (BCX7353) is an oral, once-daily inhibitor of plasma kallikrein in development for the prophylaxis of hereditary angioedema (HAE) attacks.

OBJECTIVE

Our aim was to determine the efficacy, safety, and tolerability of berotralstat in patients with HAE over a 24-week treatment period (the phase 3 APeX-2 trial).

METHODS

APeX-2 was a double-blind, parallel-group study that randomized patients at 40 sites in 11 countries 1:1:1 to receive once-daily berotralstat in a dose of 110 mg or 150 mg or placebo (Clinicaltrials.gov identifier NCT03485911). Patients aged 12 years or older with HAE due to C1 inhibitor deficiency and at least 2 investigator-confirmed HAE attacks in the first 56 days of a prospective run-in period were eligible. The primary efficacy end point was the rate of investigator-confirmed HAE attacks during the 24-week treatment period.

RESULTS

A total of 121 patients were randomized; 120 of them received at least 1 dose of the study drug (n = 41, 40, and 39 in the 110-mg dose of berotralstat, 150-mg of dose berotralstat, and placebo groups, respectively). Berotralstat demonstrated a significant reduction in attack rate at both 110 mg (1.65 attacks per month; P = .024) and 150 mg (1.31 attacks per month; P < .001) relative to placebo (2.35 attacks per month). The most frequent treatment-emergent adverse events that occurred more with berotralstat than with placebo were abdominal pain, vomiting, diarrhea, and back pain. No drug-related serious treatment-emergent adverse events occurred.

CONCLUSION

Both the 110-mg and 150-mg doses of berotralstat reduced HAE attack rates compared with placebo and were safe and generally well tolerated. The most favorable benefit-to-risk profile was observed at a dose of 150 mg per day.

Antisense Inhibition of Prekallikrein to Control Hereditary Angioedema

Hereditary angioedema is characterized by recurrent and unpredictable episodes of subcutaneous and mucosal swelling that can be life threatening. IONIS-PKK-L_Rx is a ligand-conjugated antisense oligonucleotide designed for receptor-mediated delivery to hepatocytes. In a compassionate-use pilot study, two patients with severe bradykinin-mediated angioedema were initially administered weekly subcutaneous injections of the unconjugated parent drug, IONIS-PKK_Rx, for 12 to 16 weeks, after which they received IONIS-PKK-L_Rx at a dose of 80 mg every 3 to 4 weeks for 7 to 8 months. Treatment was accompanied by a reduction in the angioedema attack rate. (Funded by Amsterdam UMC.).

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.

Severe plasma prekallikrein deficiency: Clinical characteristics, novel KLKB1 mutations, and estimated prevalence

BACKGROUND

Severe plasma prekallikrein (PK) deficiency is an autosomal-recessive defect characterized by isolated activated partial thromboplastin time prolongation. To date, no comprehensive methodologically firm analysis has investigated the diagnostic, clinical, and genetic characteristics of PK deficiency, and its prevalence remains unknown.

PATIENTS/METHODS

We described new families with PK deficiency, retrieved clinical and laboratory information of cases systematically searched in the (gray) literature, and collected blood of these cases for complementary analyses. The Genome Aggregation Database (gnomAD) and the population-based Gutenberg Health Study served to study the prevalence of mutations and relevant genetic variants.

RESULTS

We assembled a cohort of 111 cases from 89 families and performed new genetic analyses in eight families (three unpublished). We identified new KLKB1 mutations, excluded the pathogenicity of some of the previously described ones, and estimated a prevalence of severe PK deficiency of 1/155 668 overall and 1/4725 among Africans. One individual reported with PK deficiency had, in fact, congenital kininogen deficiency associated with decreased PK activity. One quarter of individuals had factor XII clotting activity below the reference range. Four major bleeding events were described in 96 individuals, of which 3 were provoked, for a prevalence of 4% and an annualized rate of 0.1%. The prevalence of cardiovascular events was 15% (6% <40 years; 21% 40-65 years; 33% >65 years) for an annualized rate of 0.4%.

CONCLUSIONS

We characterized the genetic background of severe PK deficiency, critically appraised mutations, and provided prevalence estimates. Our data on laboratory characteristics and clinical course of severe PK deficiency may have clinical implications.

Development of the Angioedema Control Test-A patient-reported outcome measure that assesses disease control in patients with recurrent angioedema

BACKGROUND

Recurrent angioedema (AE) is an important clinical problem in the context of chronic urticaria (mast cell mediator-induced), ACE-inhibitor intake and hereditary angioedema (both bradykinin-mediated). To help patients obtain control of their recurrent AE is a major treatment goal. However, a tool to assess control of recurrent AE is not yet available. This prompted us to develop such a tool, the Angioedema Control Test (AECT).

METHODS

After a conceptional framework was developed for the AECT, a list of potential AECT items was generated by a combined approach of patient interviews, literature review and expert input. Subsequent item reduction was based on impact analysis, inter-item correlation, additional predefined criteria for item performance, and a review of the item selection process for content validity. Finally, an instruction section was generated, and an US-American-English version was developed by a structured translation process.

RESULTS

A 4-item AECT with recall periods of 4 weeks and 3 months was developed based on 106 potential items tested in 97 patients with mast cell mediator-induced (n = 49) or bradykinin-mediated recurrent AE (n = 48). Eighty-four items were excluded based on impact analysis. The remaining 22 items could be further reduced by a method-mix of inter-item correlation, additional predefined criteria for item performance and review for content validity.

CONCLUSIONS

The AECT is the first tool to assess disease control in recurrent AE patients. Its retrospective approach, its brevity and its simple scoring make the AECT ideally suited for clinical practice and trials. Its validity and reliability need to be determined in future independent studies.

Self-Management Plans in Patients with Hereditary Angioedema: Strategies, Outcomes and Integration into Clinical Care

Chronic conditions, whether genetic or acquired, impose a significant burden on health care systems with high utilisation of hospital and emergency department resources. Self-management is increasingly recognised as one of the pillars in models of care for those with long-term medical conditions. Hereditary angioedema (HAE) is a rare genetic disorder inherited in an autosomal dominant fashion. It is characterised by the occurrence of unpredictable attacks of swelling (angioedema) affecting many body parts including subcutaneous tissues, the gut mucosa and the upper airway. For those affected, it is associated with a high burden of illness and poor quality of life as a result of its unpredictability and the threat of asphyxiation from upper airway oedema or severe pain from abdominal involvement. Prompt recognition and appropriate treatment are necessary to avoid the pain and suffering associated with attacks and to manage life-threatening laryngeal swellings that around 50% of HAE patients will experience in their lifetime. Since the early 2000s, a number of very effective, albeit expensive, treatment options have become available, at least in some countries. Utilisation of these options within a written patient self-management plan provides the most satisfactory treatment outcomes and improves patient quality of life. Successful self-management depends on a productive partnership between patient and health care professional, with patient education the cornerstone of a successful outcome. This is a dynamic process, particularly in a condition such as HAE where frequency and severity of attacks may vary given different life circumstances.

Biological therapy in hereditary angioedema: transformation of a rare disease

Introduction: Hereditary angioedema, a disabling condition, with high mortality when untreated, is caused by C1 inhibitor deficiency and other regulatory disorders of bradykinin production or metabolism. This review covers the remarkable progress made in biological therapies for this rare disorder.Areas covered: Over the past 10 years, several evidence-based parenteral treatments have been licensed, including two plasma-derived C1 inhibitor replacement therapies and one recombinant C1 inhibitor replacement for acute treatment of angioedema attacks and synthetic peptides for inhibition of kallikrein or bradykinin B2 receptors, with oral small molecule treatments currently in clinical trial. Moreover, recent advances in prophylaxis by subcutaneous C1 inhibitor to restore near-normal plasma function or by humanized antibody inhibition of kallikrein have resulted in freedom from symptoms for a high proportion of those treated.Expert opinion: This plethora of treatment possibilities has come about as a result of recent scientific advances. Collaboration between patient groups, basic and clinical scientists, physicians, nurses, and the pharmaceutical industry has underpinned this translation of basic science into treatments and protocols. These in their turn have brought huge improvements in prognosis, quality of life and economic productivity to patients, their families, and the societies in which they live.

Validation of the Angioedema Control Test (AECT)-A Patient-Reported Outcome Instrument for Assessing Angioedema Control

BACKGROUND

Recurrent angioedema (RA) is an important clinical problem in routine care and emergency medicine. As of recently, the only validated tools to specifically assess disease status in patients with RA were diary-type activity assessments and angioedema-related quality-of-life questionnaires. Although these tools are particularly helpful in clinical studies, they were not designed to determine disease control or to guide treatment decisions. To close this gap, the Angioedema Control Test (AECT) was published recently.

OBJECTIVE

To test the AECT for its validity and reliability, and to identify a cutoff value to aid treatment decisions.

METHODS

Two AECT versions with a recall period of 4 weeks (AECT-4wk) and 3 months (AECT-3mo) were tested for their internal consistency and test-retest reliability, convergent and known-groups validity as well as screening accuracy in 81 patients with RA with bradykinin-mediated angioedema, mast cell mediator-mediated angioedema, or idiopathic angioedema.

RESULTS

Both AECT versions showed excellent internal consistency reliability with a Cronbach alpha value of more than 0.85 and test-retest reliability with an intraclass correlation coefficient greater than 0.9. The convergent validity of both AECT versions was high. Both tools showed strong correlations with anchors of disease control, angioedema frequency, and health-related quality of life. A stratification of AECT scores into different levels of disease control together with a receiver-operating characteristic curve analysis suggested a cutoff value of 10 or more points to identify patients with well-controlled RA versus less than 10 points to identify patients with poorly controlled disease for both AECT versions.

CONCLUSIONS

The AECT is the first valid and reliable patient-reported outcome measure to assess disease control in patients with RA.

An update on the genetics and pathogenesis of hereditary angioedema

Hereditary angioedema (HAE) is an uncommon genetic disorder characterized by recurrent episodes of edema involving subcutaneous tissue and submucosa. The pathogenesis of HAE reflects an intricate coordinated regulation of components of complement, kinin and hemostatic pathway. Till date, mutations in 4 different genes have been identified to cause HAE which includes serine protease inhibitor G1 (SERPING1), factor XII (F12), plasminogen (PLG) and angiopoietin 1 (ANGPT 1). These mutations lead to increased bradykinin 2 receptor mediated signalling via increased production of bradykinin except mutations in ANGPT1 gene that disturbs the cytoskeletal assembly of vascular endothelial cells. In this review we aim to summarize the recent advances in the pathogenesis and genetics of HAE. We also provide an overview of possible future prospects in the identification of new genetic defects in HAE.