Hereditary angiodema: a current state-of-the-art review, IV: short- and long-term treatment of hereditary angioedema: out with the old and in with the new?

Chemical engineering of CRISPR-Cas systems for therapeutic application

Clustered regularly interspaced short palindromic repeats (CRISPR) technology has transformed molecular biology and the future of gene-targeted therapeutics. CRISPR systems comprise a CRISPR-associated (Cas) endonuclease and a guide RNA (gRNA) that can be programmed to guide sequence-specific binding, cleavage, or modification of complementary DNA or RNA. However, the application of CRISPR-based therapeutics is challenged by factors such as molecular size, prokaryotic or phage origins, and an essential gRNA cofactor requirement, which impact efficacy, delivery and safety. This Review focuses on chemical modification and engineering approaches for gRNAs to enhance or enable CRISPR-based therapeutics, emphasizing Cas9 and Cas12a as therapeutic paradigms. Issues that chemically modified gRNAs seek to address, including drug delivery, physiological stability, editing efficiency and off-target effects, as well as challenges that remain, are discussed.

Hereditary Angioedema With Normal C1 Inhibitor: US Survey of Prevalence and Provider Practice Patterns

BACKGROUND

Hereditary angioedema (HAE) with normal C1-INH (HAE-nl-C1INH) is phenotypically similar to HAE resulting from C1-INH deficiency (HAE-C1INH). Confirmatory diagnostic tests for HAE-nl-C1INH are limited and few clinical study data exist regarding management of the condition. Therefore, survey studies may provide initial estimates of prevalence, diagnosis, and management patterns of this condition.

OBJECTIVE

To estimate the prevalence and describe current management patterns for HAE-nl-C1INH in the United States (US).

METHODS

We conducted an Internet-based survey of US physicians to estimate the prevalence of the HAE-nl-C1INH population in the United States. Potential participating physicians were identified from the US Hereditary Angioedema Association database and IQVIA Xponent prescription database. Eligible physicians were invited to complete an online survey between June and September 2021.

RESULTS

A total of 113 physicians provided data for the estimation of HAE-nl-C1INH prevalence and 81 physicians treating HAE-nl-C1INH patients provided data about treatment patterns. In bias-corrected analysis, we estimated 1,230 to 1,331 HAE-nl-C1INH patients within the United States between May 2019 and April 2020. Mean time to diagnosis for HAE-nl-C1INH was approximately 6 years (range, 2.4-13.5 years). Response to medication was commonly used to inform diagnosis (antihistamine response or nonresponse used by 73% of physician respondents, corticosteroids by 57%, or HAE-specific medications by 74%), and Factor XII genetic testing was used by 43%.

CONCLUSIONS

These survey data provide estimates of HAE-nl-C1INH prevalence in the United States as well as current diagnosis and management strategies. Results may be useful for developing studies to assess treatment efficacy and safety, and potentially improve the diagnosis for and management of this patient population.

Efficacy, pharmacokinetics, and safety of subcutaneous C1-esterase inhibitor as prophylaxis in Japanese patients with hereditary angioedema: Results of a Phase 3 study

BACKGROUND

Hereditary angioedema (HAE) is a rare and potentially life-threatening genetic disorder characterized by recurrent attacks of angioedema. HAE types I and II result from deficient or dysfunctional C1-esterase inhibitor (C1-INH). This Phase 3 study assessed the efficacy, pharmacokinetics (PK), and safety of subcutaneous (SC) C1-INH in Japanese patients with HAE.

METHODS

The prospective, open-label, multicenter, single-arm Phase 3 study recruited patients with HAE types I or II to an initial run-in period, followed by a 16-week treatment period where patients received 60 IU/kg C1-INH (SC) twice weekly. The two primary endpoints were the time-normalized number of HAE attacks per month and C1-INH functional activity at Week 16.

RESULTS

Nine patients entered the treatment period and completed the study. Treatment with C1-INH (SC) significantly reduced the mean monthly attack rate from 3.7 during the run-in period to 0.3 during treatment (exploratory p value of within-patient comparison = 0.004). After the last dose of C1-INH (SC) at Week 16, the mean trough concentration of C1-INH was 59.8%, and the mean area under the plasma concentration-time curve to the end of the dosing period and to the last sample were 5317.1 and 13,091.5 h•%, respectively. During the study, there were no deaths, serious adverse events, or adverse events leading to study discontinuation.

CONCLUSIONS

C1-INH (SC) (60 IU/kg twice weekly) was efficacious and well tolerated as a prophylaxis against HAE attacks in Japanese patients with HAE types I or II, which was supported by the increased and maintained C1-INH functional activity. EudraCT Number 2019-003921-99; JapicCTI-205273.

Mitigating Disparity in Health-care Resources Between Countries for Management of Hereditary Angioedema

Hereditary angioedema (HAE) is a rare genetic disorder characterized by recurrent episodes of skin and mucosal edema. The main treatment goal is to enable a “normal life” for all patients. However, due to high costs, there are limited options for the management of HAE in most developing and low-income countries. As a result, most of the recommended first-line treatments are not available. In this review, we attempt to highlight the disparities in health-care resources for the management of patients with HAE amongst different countries. Data was collected from HAE experts in countries who provide tabulated information regarding management and availability of HAE treatments in their countries. We reviewed the two most recent international HAE guidelines. Using India, the world’s second most populous country, as a paradigm for HAE management in lower-income countries, we reviewed the evidence for second-line and non-recommended practices reported by HAE experts. Results suggest significant inequities in provision of HAE services and treatments. HAE patients in low-income countries do not have access to life-saving acute drugs or recently developed highly effective prophylactic medications. Most low-income countries do not have specialized HAE services or diagnostic facilities, resulting in consequent long delays in diagnosis. Suggestions for optimizing the use of limited resources as a basis for future discussion and reaching a global consensus are provided. There is an urgent need to improve HAE services, diagnostics and treatments currently available to lower-income countries. We recommend that all HAE stakeholders support the need for global equity and access to these essential measures.

Psychology and hereditary angioedema: A systematic review

Background: Hereditary angioedema (HAE) is caused by mutations in the C1 inhibitor (C1-INH) gene Serpin Family G Member 1(SERPING1), which results in either the decreased synthesis of normal C1-INH (C1-INH-HAE type I) or expression of unfunctional C1-INH (C1-INH-HAE type II). In recent studies, emotional stress was reported by patients as the most common trigger factor for C1-INH-HAE attacks. Moreover, patients reported considerable distress over the significant variability and uncertainty with which the disease manifests, in addition to the impact of physical symptoms on their overall quality of life. Objective: We did a systematic review of the literature to shed light on the advancements made in the study of how stress and psychological processes impact C1-INH-HAE. Methods: All of the articles on C1-INH-HAE were analyzed up to December 2019. Both medical data bases and psychological data bases were examined. The keywords (KWs) used for searching the medical and psychological data bases were the following: "hereditary angioedema," "psychology," "stress," "anxiety," and "depression." Results: Of a total of 2549 articles on C1-INH-HAE, 113 articles were retrieved from the literature search by using the related KWs. Twenty-one of these articles were retrieved, examined, and classified. Conclusion: Although the literature confirmed that stress may induce various physical diseases, it also warned against making simplistic statements about its incidence that did not take into account the complexity and multicausality of factors that contribute to C1-INH-HAE expression.

A hereditary angioedema screening in two villages, based on an index case, and identification of a novel mutation, "1033G>T", at the SERPING1 gene

Introduction

Hereditary angioedema (HAE) may be fatal and diagnosis can be delayed up to 10 years. We aimed to screen HAE in two villages based on an index case of HAE and to investigate for the mutation of the C1 esterase inhibitor (C1-INH) gene.

Material and methods

A total of 124 people were screened in two villages. The frequency and severity of symptoms were scored. C4, C1-INH levels and C1-INH activity were measured. We investigated for mutations of the C1-INH gene.

Results

Thirty-five cases of type I HAE and 7 cases of type II HAE were determined. Thirty-one (73.8%) patients diagnosed with HAE were 18 years old or younger. There was a positive correlation between C4 levels, C1-INH levels (p < 0.0001, r = 0.81), and C1-INH activity levels (p < 0.0001, r = 0.631) and between the age at diagnosis and severity score (p < 0.0001, r = 0.651). A positive correlation was found between the age at first symptom onset and C4 levels (p = 0.002, r = 0.774), and C1-INH levels (p = 0.006, r = 0.714). A marginally significant negative correlation was found between C1-INH activity levels and severity scores (p = 0.1, r = -0.515). We identified a novel heterozygous 1033G>T missense variant of the C1-INH gene, SERPING1, in patients with type I HAE.

Conclusions

There are long delay periods in the diagnosis of HAE and when the index case is present, family screening may be very important and even life-saving, in particular, in paediatric patients without symptoms. Furthermore, the present study provides evidence to link a novel mutation, c.1033G>T, to the development of HAE in a large HAE family from Turkey.

Hereditary angioedema with C1 inhibitor (C1-INH) deficit: the strength of recognition (51 cases)

Hereditary angioedema (HAE) is a rare autosomal dominant disease due to C1 esterase inhibitor deficiency (C1-INH). The disease is characterized by subcutaneous and submucosal edema in the absence of urticaria due to the accumulation of bradykinin. This descriptive study aimed to evaluate the clinical characteristics of patients with a confirmed diagnosis of HAE referred to our Outpatient Clinic between December 2009 and November 2017. Fifty-one patients (38 F, 13 M) with a mean age of 32 years (range: 7–70 y) were included. Family history of HAE was reported in 70% (36/51) of the cases; 33/46 patients became symptomatic by 18 years of age. The median time between onset of symptoms and diagnosis was 13 years (3 mo–50 y). The most frequent triggering factors for attacks were stress (74.4%), trauma (56.4%), and hormonal variations (56%). The main symptoms were subcutaneous edema in 93.5% (43/46) of patients, gastrointestinal symptoms in 84.8% (39/46), and obstruction in the upper airways in 34.8% (16/46). Hospitalization occurred in 65.2%, of whom 13.3% had to be transferred to the Intensive Care Unit. Prophylactic treatment was instituted in 87% (40/46) of patients, and 56.5% (26/46) required additional treatment to control attacks. Owing to our data collection over a period of 8 years, a significant number of patients were identified by this HAE reference center. Despite early recognition and prophylactic treatment, a high percentage of patients were hospitalized. HAE is still diagnosed late, reinforcing the need for more reference centers specialized in diagnosis and educational projects for health professionals.

A Case of Type 2 Hereditary Angioedema With SERPING1 Mutation

Hereditary angioedema is a disease of congenital deficiency or functional defect in the C1 esterase inhibitor (C1-INH) consequent to mutation in the SERPING1 gene, which encodes C1-INH. This disease manifests as recurrent, non-pitting, non-pruritic subcutaneous, or submucosal edema as well as an erythematous rash in some cases. These symptoms result from the uncontrolled localized production of bradykinin. The most commonly affected sites are the extremities, face, gastrointestinal tract, and respiratory system. When the respiratory system is affected by hereditary angioedema, swelling of the airway can restrict breathing and lead to life-threatening obstruction. Herein, we report a case of a 24-year-old woman with type 2 hereditary angioedema who presented with recurrent episodic abdominal pain and swelling of the extremities. She had no family history of angioedema. Although her C4 level was markedly decreased (3.40 mg/dL; normal range: 10-40 mg/dL), she presented with a very high C1-INH level (81.0 mg/dL; normal range: 21.0-39.0 mg/dL) and abnormally low C1-INH activity (less than 25%; normal range: 70%-130%). The SERPING1 gene mutation was confirmed in this patient. She was treated with prophylactic tranexamic acid, as needed, and subsequently reported fewer and less severe episodes. To our knowledge, this is the first reported case of type 2 hereditary angioedema in Korea that was consequent to SERPING1 mutation and involved a significantly elevated level of C1-INH as well as a low level of C1-INH activity.

Hereditary angioedema (HAE): a cause for recurrent abdominal pain

A 44-year-old Hispanic woman presented to the emergency room with a 2-day history of sudden onset of severe cramping left lower quadrant abdominal pain associated with ∼20 episodes diarrhoea. Abdominal CT scan exhibited bowel wall oedema and acute extensive colitis. On the basis of the preliminary diagnosis of acute abdomen, the patient was admitted under the surgical team and treated for acute colitis. Since her family history was significant for hereditary angioedema (HAE), complement studies were performed which revealed low complement C4 levels and abnormally low values of C1q esterase inhibitor. Thus, the diagnosis of HAE type I was established. This case report summarises that the symptoms of HAE are often non-specific, hence making the underlying cause difficult to diagnose.

Thyroid hormones and complement parameters in hereditary angioedema with C1-inhibitor deficiency

BACKGROUND

Thyroid hormones control and up-regulate the synthesis of many plasma proteins.

OBJECTIVE

To explore possible associations between thyroid hormone and complement levels in patients with hereditary angioedema resulting from the deficiency of the C1-inhibitor (C1-INH-HAE).

METHODS

In this case-control study, serum thyrotropin, free triiodothyronine (FT3), and free thyroxine (FT4) levels, anti-thyroid peroxidase and antithyroglobulin antibody titers, and C1-INH concentrations were measured in 117 euthyroid patients with C1-INH-HAE and compared with their clinical properties. The control group comprised 150 healthy, age- and sex-matched, euthyroid individuals.

RESULTS

The thyrotropin and antithyroglobulin levels were similar between the patients and the controls. Significantly lower FT3 (P < .001) and FT4 (P = .002) levels, as well as higher anti-thyroid peroxidase titers (P < .001), were seen in the patients with C1-INH-HAE. The proportion of patients with reduced C1-INH activity was greater among those with below-median FT4 levels than among those with above-median values (P = .02). Patients who experienced more edematous attacks per year had lower FT4 levels (within the normal range) than those afflicted by fewer episodes (P = .01). The FT3 and FT4 levels were significantly higher in patients undergoing long-term danazol therapy than in those who did not receive this drug (P = .01 and P = .02, respectively). The proportion of patients with FT4 levels in the below-median range was higher in the subset with increased d-dimer concentration (P = .009).

CONCLUSION

Minor variations of the thyroid hormone levels (within the reference range) can influence the function of C1-INH in C1-INH-HAE. Our findings suggest a role for the endocrine system in the pathophysiology of C1-INH-HAE.

Frequency of the virilising effects of attenuated androgens reported by women with hereditary angioedema

BACKGROUND

Danazol, a drug extensively used in the management of hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE), has various side effects. This study investigated the virilizing actions of this drug in 31 danazol-treated female patients with HAE-C1-INH. We compared our findings with those of healthy controls and with literature data.

METHODS

The patients were interviewed individually about the type and severity of the virilizing effects, as well as about their satisfaction with danazol therapy.

RESULTS

The average duration of danazol treatment was 10.31 years [2 to 23] and its mean daily dose was 131.7 mg [33 to 200]. The most common adverse effects were hirsutism (n=14), weight gain (n=13), and menstrual disturbances (n=8). The severity of danazol adverse effects did not differ by duration of treatment or by daily drug dose. The mean level of patient satisfaction with the treatment was high. The comparison of age-matched healthy controls and of HAE-C1-INH patients receiving danazol did not demonstrate a statistically higher incidence of any of the monitored symptoms in the danazol group.

CONCLUSIONS

Our findings indicate that long-term danazol treatment - using the lowest effective dose - has only a mild virilizing effect.

Tranexamic acid as maintenance treatment for non-histaminergic angioedema: analysis of efficacy and safety in 37 patients

Angioedema (AE) is a clinical syndrome characterized by localised swelling lasting several hours. The swelling is often recurring and can be lethal if it is located in the laryngeal region. Much progress has been made recently in the treatment of acute episodes, but no consensus has been reached on maintenance treatment. We have performed a national retrospective observational study to assess the use of tranexamic acid (TA) as maintenance treatment for non-histaminergic AE [hereditary AE (HAE) or idiopathic non-histaminergic AE]. Records for 64 cases were collected from 1 October 2012 to 31 August 2013; 37 of these were included (12 HAE with C1-inhibitor deficiency, six with HAE with normal C1-inhibitor and 19 idiopathic non-histaminergic AE). When treated with TA over six months, the number of attacks was reduced by 75% in 17 patients, 10 patients showed a lower level of reduction and 10 had the same number of attacks. In no instances were symptoms increased. No thromboembolic events were observed, and the main side effects were digestive in nature. Thus, TA, which is well tolerated and inexpensive, appears to be an effective maintenance treatment for some patients with HAE or idiopathic non-histaminergic AE.

Recent advances in the management of hereditary angioedema

Hereditary angioedema (HAE) is a rare genetic condition that manifests as painful and potentially life-threatening episodic attacks of cutaneous and submucosal swelling. It results from functional deficiency of C1 inhibitor (C1 INH), which is a regulator of the complement, fibrinolytic, kinin (contact), and coagulation systems. In patients with HAE, the low plasma concentration of functional C1 INH leads to overactivation of the kinin cascade and local release of bradykinin. Bradykinin is responsible for the pain, vascular permeability changes, and edema associated with HAE. Until recently, therapeutic options for HAE have been very limited. Many new therapies have emerged, however, such as C1 INH replacement drugs and medications aimed at components of the contact system (eg, plasma kallikrein inhibitor and bradykinin B2 receptor antagonist). The authors review current and novel treatments for patients with HAE.

Does angiotensin-converting enzyme inhibitor use exacerbate hereditary angioedema?

BACKGROUND

Approximately 2% of angioedema (AE) patients have a hereditary or an acquired deficiency of the complement 1 (C1) esterase inhibitor (C1 INH) gene. Some case reports indicate an association between angiotensin-converting enzyme inhibitor (ACEI) use and exacerbation of hereditary AE (HAE).

OBJECTIVE

The aim of this retrospective study is to investigate the association between HAE and ACEI use in a larger patient population.

METHODS

A retrospective chart review of patients who presented with AE and patients with diagnostic serum assays for functional C1 INH, C1 INH antigenic protein, C1q, C1q immune complex (C1q IC), and complement 4 (C4) regardless of medical complaint. Descriptive statistics were used to analyze the data.

RESULTS

A total of 1594 patients had complement levels measured (136 C1 INH, 55 C1q, 10 C1q IC, and 1500 C4), of which 156 (9.7%) patients presented with AE. Angiotensin-converting enzyme inhibitor use was documented in 747 (47%) patients. Low C1 INH was detected in one patient with recurrent AE who was not taking ACEI. Another patient who presented with recurrent AE was found to have systemic lupus erythematosus with abnormal C4, C1q, and C1q IC, but normal C1 INH. A low C4 level was present in 94 patients, 4 of which had AE.

CONCLUSIONS

The risk of exacerbating HAE by ACEI might be present, but we did not find any association in this retrospective study. Further studies are needed to determine the existence of this association.

WAO Guideline for the Management of Hereditary Angioedema

Hereditary Angioedema (HAE) is a rare disease and for this reason proper diagnosis and appropriate therapy are often unknown or not available for physicians and other health care providers. For this reason we convened a group of specialists that focus upon HAE from around the world to develop not only a consensus on diagnosis and management of HAE, but to also provide evidence based grades, strength of evidence and classification for the consensus. Since both consensus and evidence grading were adhered to the document meets criteria as a guideline. The outcome of the guideline is to improve diagnosis and management of patients with HAE throughout the world and to help initiate uniform care and availability of therapies to all with the diagnosis no matter where the residence of the individual with HAE exists.

The dermatology view of hereditary angio-oedema: practical diagnostic and management considerations

Hereditary angio-oedema (HAE) is characterized by recurrent, localized, non-pitting, non-pruritic, non-urticarial oedema. Nearly all patients experience skin swelling as a feature of HAE. There may be painful abdominal attacks, accompanied by nausea and vomiting. The disease is life-threatening should laryngeal oedema occur. HAE results from a deficiency or dysfunction of C1 inhibitor, a plasma protein with an important role in regulating the contact, complement and fibrinolytic systems. Effective management of HAE should include a plan for treatment of attacks, as well as routine and preprocedure prevention. Acute and prophylactic therapy with C1 inhibitor therapy for correcting the underlying deficiency in HAE is a valuable option.

New treatment options for acute edema attacks caused by hereditary angioedema

PURPOSE

New treatment options for acute edema attacks caused by hereditary angioedema (HAE) are reviewed.

SUMMARY

HAE is characterized by mutations in the C1 inhibitor gene leading to either a reduced expression of C1 inhibitor in the plasma or expression of a functionally impaired C1 inhibitor. HAE is classified into two major types based on the cause of the C1 inhibitor deficiency. Type I HAE is defined by a reduced expression of C1 inhibitor in the plasma, whereas type II HAE is characterized by the expression of a dysfunctional C1 inhibitor protein. Clinical data were reviewed for C1 inhibitor, ecallantide, and icatibant in the treatment of acute edema attacks caused by HAE. C1 inhibitor leads to a faster onset of edema relief and is effective in decreasing the duration of edema. Dosing strategies include fixed dosing and weight-based dosing. Optimal dosing strategies have not been established, but fixed dosing (500-1000 units) or 20 units/kg has been effective in clinical trials and reports. No comparative trials suggest that one strategy is superior to another; however, the approved labeling for acute treatment is based on weight. Ecallantide is also efficacious for treating acute episodes; however, the available evidence is limited to a single published trial. Icatibant has shown variable effects in two trials with placebo and active controls.

CONCLUSION

In patients with HAE, most edema episodes only involve the skin and gastrointestinal tract, though airway obstruction caused by laryngeal angioedema is the most common cause of death. I.V. C1 inhibitor should be considered first-line treatment for acute edema attacks because of its fast onset of action and effectiveness, though it is not clear whether fixed or weight-based dosing is preferred. Ecallantide can be considered as a second-line treatment option.

588 Delayed Diagnosis of Hereditary Angioedema. A Case Report

Background

Hereditary angioedema (HAE) was first described by Quincke in 1882 and appointed by Osler in 1888, is a rare disease caused by deficiency of gene esterase inhibitor C1 (C1 INH). Prevalence varies from 1:10,000 to 1:150,000. The attacks are usually sporadic and often associated with traumatic or stressful events. Treatment included management of acute attacks and prophylactic therapy in specific situations where attacks may occur.

Methods

A 40-year-old male with a family history of father facial angioedema. He had experienced 15 episodes of angioedema during the previous 5 years. During these events than lasted 3 to 5 days edema affected his eyelids, lips, hands, feet and testicles. And sometimes was associated to abdominal pain and shortness of breath. He went several times to medical office and emergency room, where he received treatment with antihistamines without improvement.

Results

The laboratory evaluation of complement components showed C4 2s0.8 (NV 20–50), CH50 10.1 (NV 20–50), C1 inhibitor quantitative <1.2 ng Eq/mL (NV > 10.7), and C1 esterase inhibitor functional 104% (NV > 67%), once the diagnosis of type I hereditary angioedema was done, we started danazol therapy that has prevented recurrence of symptoms.

Conclusions

It is important to do a detailed history for the diagnosis and treatment in cases of angioedema. Most patients improve when receiving the right treatment. Recurrent angioedema events even with treatment, the physician must search for malignity and/or autoimmunity disease.

Diagnosis and management of hereditary angioedema: an emergency medicine perspective

BACKGROUND

Hereditary angioedema (HAE) is a rare and often debilitating condition associated with substantial morbidity and mortality in the absence of appropriate intervention. An underlying deficiency in functional C1-inhibitor (C1-INH) protein induces a vulnerability to unchecked activation of the complement, contact, and coagulation/fibrinolytic systems. The clinical consequence is a pattern of recurring attacks of non-pitting, non-pruritic edema, the urgency of which varies by the affected site. Laryngeal edema can escalate rapidly to asphyxiation, and severe cases of abdominal swelling can lead to hypovolemic shock.

OBJECTIVES

This report reviews the emergency diagnosis and treatment of hereditary angioedema and the impact of recently introduced treatments on treatment in the United States.

DISCUSSION

Until recently, emergency physicians in the United States were hindered by the lack of rapidly effective treatment options for HAE attacks. In this article, general clinical and laboratory diagnostic procedures are reviewed against the backdrop of two case studies: one patient presenting with a known history of HAE and one with previously undiagnosed HAE. In many countries outside the United States, plasma-derived C1-INH concentrate has for decades been the first-line treatment for acute attacks. The end of 2009 ushered in a new era in the pharmacologic management of HAE attacks in the United States with the approval of two new treatment options for acute treatment: a plasma-derived C1-INH concentrate and a kallikrein inhibitor.

CONCLUSION

With access to targeted and effective treatments, emergency physicians are now better equipped for successful and rapid intervention in urgent HAE cases.

[Hereditary angioedema: a therapeutic revolution]

Hereditary angioedema is a rare disease, often diagnosed with delay because of a heterogeneous clinical presentation. Before diagnosis, patients frequently present subcutaneous edema or abdominal pains during many years. Laryngeal edema can be life-threatening. Hereditary angioedema may impair the quality of life of the patients and their social and professional life. It is important that the physicians recognize and treat the disease as soon as possible after the first attacks. Since the past five years, new drugs developed for hereditary angioedema have changed dramatically the outcome of this disorder. The objective of this review is to detail the new therapeutic guidelines.

Conestat alfa for the treatment of angioedema attacks

Recently, multiple C1 inhibitor (C1-INH) replacement products have been approved for the treatment of hereditary angioedema (HAE). This review summarizes HAE and its current treatment modalities and focuses on findings from bench to bedside trials of a new C1-INH replacement, conestat alfa. Conestat alfa is unique among the other C1-INH replacement products because it is produced from transgenic rabbits rather than derived from human plasma donors, which can potentially allow an unlimited source of drug without any concern of infectious transmission. The clinical trial data generated to date indicate that conestat alfa is safe and effective for the treatment of acute HAE attacks.

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

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

Long-term efficacy of danazol treatment in hereditary angioedema

BACKGROUND

No systematic study has been published yet on the long-term efficacy of attenuated androgens in hereditary angioedema (HAE). Our aim was to conduct a follow-up study in two (German and Hungarian) cohorts of HAE patients (45 and 39 patients, respectively) undergoing uninterrupted treatment for 6 years with similar (starting dose 128 ± 78 mg per day and 136 ± 70 mg per day, respectively) and constant doses of danazol.

DESIGN

The frequencies of subcutaneous, abdominal and laryngeal attacks were recorded each year.

RESULTS

The annual frequency of all the three types of attacks was significantly lower during the first year of danazol treatment, compared to the last year before baseline. During subsequent years in Hungarian patients, the frequency of both subcutaneous and abdominal attacks - but not that of laryngeal attacks - increased significantly. In the case of abdominal attacks, a significant increase in the attack frequency was observed only in female patients. In the German cohort, by contrast, no change in the frequency of either type of attack was found during the 6-year study period.

CONCLUSIONS

The differences observed between these cohorts cannot be related to drug dose, the age or gender distribution of subjects or the age at the onset of symptoms or the length of diagnostic delay in the patients. There were, however, marked differences in the baseline pattern of attacks: significantly - 3 times - more abdominal attacks were recorded in German patients. Further studies are necessary to clarify the mechanism of these findings.

Hereditary Angioedema: A Clinical Review for the Otolaryngologist

Hereditary angioedema (HAE) is a relatively rare genetic disorder that is usually characterized by either low levels of C1 esterase inhibitor (C1-INH) or the presence of dysfunctional C1-INH. It can present with relatively mild and self-limiting symptoms, but it is also potentially fatal; the most common cause of death is asphyxiation secondary to edema of the upper airway. The diagnosis of HAE, especially in the emergency situation, is not straightforward. HAE must be distinguished from several other types of angioedema that require different management approaches. Management approaches include trigger avoidance and pharmacologic therapy; the latter has traditionally involved the administration of attenuated androgens and antifibrinolytics. Recently, a new class of agent—C1-INH—has been introduced in the United States. This article provides an update on the pathophysiology, clinical picture, diagnosis, prophylaxis, and acute treatment of HAE. We must keep HAE in mind as a possible diagnosis whenever we are faced with a case of unexplained angioedema if we are to take advantage of the effective and more specific therapies that are becoming available.

Brazilian guidelines for the diagnosis and treatment of hereditary angioedema

Hereditary angioedema is an autosomal dominant disease characterized by edema attacks with multiple organ involvement. It is caused by a quantitative or functional deficiency of the C1 inhibitor, which is a member of the serine protease inhibitor family. Hereditary angioedema is unknown to many health professionals and is therefore an underdiagnosed disease. The causes of death from hereditary angioedema include laryngeal edema with asphyxia. The estimated mortality rate in patients in whom the disease goes undetected and who are therefore incorrectly treated is 25-40%. In addition to edema of the glottis, hereditary angioedema often results in edema of the gastrointestinal tract, which can be incapacitating. Patients with hereditary angioedema may undergo unnecessary surgical interventions because the digestive tract can be the primary or only organ system involved, thus mimicking acute surgical abdomen. It is estimated that patients with hereditary angioedema experience some degree of disability 20-100 days per year. The Experts in Clinical Immunology and Allergy of the "Associação Brasileira de Alergia e Imunopatologia -ASBAI" developed these guidelines for the diagnosis, therapy, and management of hereditary angioedema.

Response time for ecallantide treatment of acute hereditary angioedema attacks

BACKGROUND

Hereditary angioedema (HAE) is a rare, debilitating, and potentially fatal disease characterized by acute attacks of swelling that can affect the abdomen/gastrointestinal tract, larynx, face, genitals, and extremities. Ecallantide is a novel plasma kallikrein inhibitor developed for the treatment of acute HAE attacks.

OBJECTIVE

To examine the speed of effect of ecallantide vs placebo.

METHODS

Data were integrated from 2 randomized, double-blind, placebo-controlled phase 3 trials of ecallantide in patients with HAE. Eligible patients presented within 8 hours of onset of a moderate to severe HAE attack for 1:1 randomization to receive a single dose of 30 mg of subcutaneous ecallantide or placebo. End points included time to beginning of improvement, time to sustained overall improvement, and time to significant overall improvement.

RESULTS

A total of 143 participants (70 receiving ecallantide and 73 receiving placebo) were included. The distribution curves for time to beginning of improvement demonstrated a trend in favor of ecallantide vs placebo within 4 hours (P(log rank) = .09). For time to onset of sustained improvement, the difference in the distribution of the curves between the 2 groups reached significance by 2 hours after dosing (P(log rank) = .04). For time to significant overall improvement, the difference in the distribution of the curves reached significance in favor of ecallantide by 90 minutes (P(log rank) = .04). The beneficial effect of ecallantide was demonstrated earliest for abdominal attacks, followed by laryngeal and peripheral attacks.

CONCLUSIONS

Ecallantide provides relief of acute HAE attack symptoms, with rapidity of response commensurate with therapeutic needs for HAE attack locations.

Diagnosis and management of angioedema with abdominal involvement: A gastroenterology perspective

Abdominal involvement in angioedema is often a challenge to diagnose. Acute onset abdominal pain is its most common presenting symptom, and misdiagnosis may lead to unnecessary surgical intervention. Familiarity with the types and presentations of angioedema can be invaluable to clinicians as they consider the differential diagnoses of a patient presenting with abdominal pain. Detailed personal and family histories, careful physical examination of the patient, combined with knowledge of angioedema types, can help clinicians perform their diagnostic evaluation. An accurate diagnosis is essential in order to provide appropriate treatment to patients with angioedema. Depending upon the diagnosis, treatment may be the avoidance of provoking factors (such as allergens or medications), inhibiting histamine-provoked reactions, or treating C1 esterase inhibitor deficiency.

Characterization of acute hereditary angioedema attacks during pregnancy and breast-feeding and their treatment with C1 inhibitor concentrate

OBJECTIVE

The objective of the study was to investigate the rates and characteristics of hereditary angioedema (HAE) attacks associated with pregnancy, delivery, and the postpartum period and their treatment with C1 esterase inhibitor (INH) concentrate.

STUDY DESIGN

This was an observational study including 22 women with type I HAE, with data collected before, during, and after 35 pregnancies (37 children) based on patient diaries, interviews, and case report forms.

RESULTS

In 83% of pregnancies, attack rates increased during pregnancy; highest mean rates occurred in the second and third trimesters. C1-INH concentrate effectively controlled attacks and was safe for mothers and children. Low-plasma C1-INH activity during pregnancy tended to be associated with an increased chance of giving birth to a child with HAE.

CONCLUSION

Increased attack rates during pregnancy in women with HAE are well controlled with C1-INH concentrate, indicating the clear benefit of integrating the availability of C1-INH concentrate into the management plan for these women during pregnancy and delivery.

Pediatric hereditary angioedema due to C1-inhibitor deficiency

Hereditary angioedema (HAE) resulting from the deficiency of the C1 inhibitor (C1-INH) is a rare, life-threatening disorder. It is characterized by attacks of angioedema involving the skin and/or the mucosa of the upper airways, as well as the intestinal mucosa. In approximately 50 per cent of cases, clinical manifestations may appear during childhood. The complex management of HAE in pediatric patients is in many respects different from the management of adults. Establishing the diagnosis early, preferably before the onset of clinical symptoms, is essential in cases with a positive family history. Complement studies usually afford accurate diagnosis, whereas molecular genetics tests may prove helpful in uncertain cases. Appropriate therapy, supported by counselling, suitable modification of lifestyle, and avoidance of triggering factors (which primarily include mechanical trauma, mental stress and airway infections in children) may spare the patient unnecessary surgery and may prevent mortality. Prompt control of edematous attacks, short-term prophylaxis and intermittent therapy are recommended as the primary means for the management of pediatric cases. Medicinal products currently used for the treatment of children with hereditary angioedema include antifibrinolytics, attenuated androgens, and C1-INH replacement therapy. Current guidelines favour antifibrinolytics for long-term prophylaxis because of their favorable safety profile but efficacy may be lacking. Attenuated androgens administered in the lowest effective dose are another option. C1-INH replacement therapy is also an effective and safe agent for children. Regular monitoring and follow-up of patients are necessary.

Management of upper airway edema caused by hereditary angioedema

Hereditary angioedema is a rare disorder with a genetic background involving mutations in the genes encoding C1-INH and of factor XII. Its etiology is unknown in a proportion of cases. Recurrent edema formation may involve the subcutis and the submucosa - the latter can produce obstruction in the upper airways and thereby lead to life-threatening asphyxia. This is the reason for the high, 30-to 50-per-cent mortality of undiagnosed or improperly managed cases. Airway obstruction can be prevented through early diagnosis, meaningful patient information, timely recognition of initial symptoms, state-of-the-art emergency therapy, and close monitoring of the patient. Prophylaxis can substantially mitigate the risk of upper airway edema and also improve the patients' quality of life. Notwithstanding the foregoing, any form of upper airway edema should be regarded as a potentially life-threatening condition. None of the currently available prophylactic modalities is capable of preventing UAE with absolute certainty.

2010 International consensus algorithm for the diagnosis, therapy and management of hereditary angioedema

BACKGROUND

We published the Canadian 2003 International Consensus Algorithm for the Diagnosis, Therapy, and Management of Hereditary Angioedema (HAE; C1 inhibitor [C1-INH] deficiency) and updated this as Hereditary angioedema: a current state-of-the-art review: Canadian Hungarian 2007 International Consensus Algorithm for the Diagnosis, Therapy, and Management of Hereditary Angioedema.

OBJECTIVE

To update the International Consensus Algorithm for the Diagnosis, Therapy and Management of Hereditary Angioedema (circa 2010).

METHODS

The Canadian Hereditary Angioedema Network (CHAEN)/Réseau Canadien d'angioédème héréditaire (RCAH) http://www.haecanada.com and cosponsors University of Calgary and the Canadian Society of Allergy and Clinical Immunology (with an unrestricted educational grant from CSL Behring) held our third Conference May 15th to 16th, 2010 in Toronto Canada to update our consensus approach. The Consensus document was reviewed at the meeting and then circulated for review.

RESULTS

This manuscript is the 2010 International Consensus Algorithm for the Diagnosis, Therapy and Management of Hereditary Angioedema that resulted from that conference.

CONCLUSIONS

Consensus approach is only an interim guide to a complex disorder such as HAE and should be replaced as soon as possible with large phase III and IV clinical trials, meta analyses, and using data base registry validation of approaches including quality of life and cost benefit analyses, followed by large head-to-head clinical trials and then evidence-based guidelines and standards for HAE disease management.

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

Introduction

Hereditary angioedema (HAE) is a rare disorder characterized by C1 esterase inhibitor (C1-INH) deficiency, resulting in periodic attacks of acute edema that can be life-threatening if they occur in the laryngeal region. We assessed the efficacy of C1-INH concentrate in the emergency treatment of rarely occurring acute laryngeal HAE attacks in a prospective, open-label clinical study.

Methods

Acute laryngeal attacks were each treated with C1-INH concentrate (Berinert) at a single dose of 20 U/kg body weight. Efficacy endpoints included time to onset of symptom relief and time to complete resolution of all symptoms, each based on the patient's assessment.

Results

All 39 laryngeal attacks in 16 patients were treated successfully. The median time to onset of symptom relief was 15 min. The median time to complete resolution of all symptoms was 8.25 h. No treatment-related serious adverse events occurred, and the treatment was well tolerated. The administration of C1-INH concentrate was not associated with any viral infections.

Conclusion

C1-INH concentrate is an effective and safe emergency treatment for providing reliable and rapid relief from the potentially life-threatening symptoms of laryngeal HAE attacks.

EDEMA4: a phase 3, double-blind study of subcutaneous ecallantide treatment for acute attacks of hereditary angioedema

BACKGROUND

Hereditary angioedema (HAE) is a genetic disorder resulting from low levels of C1-inhibitor activity that manifests as acute attacks of variable and sometimes life-threatening edema. Ecallantide is a novel potent inhibitor of human plasma kallikrein, a key mediator of the excessive formation of bradykinin associated with the signs and symptoms of an HAE attack.

OBJECTIVE

To evaluate the efficacy and safety of ecallantide in the treatment of acute HAE attacks.

METHODS

In this double-blind, placebo-controlled study, patients with a moderate to severe HAE attack were randomized 1:1 to receive 30 mg of subcutaneous ecallantide or placebo. The primary efficacy end point was change from baseline in mean symptom complex severity score 4 hours after dosing. Additional end points included treatment outcome score 4 hours after dosing and maintenance of significant overall improvement through 24 hours.

RESULTS

Ninety-six patients were enrolled. Mean (SD) change from baseline in mean symptom complex severity score 4 hours after dosing was significantly greater with ecallantide use (-0.8 [0.6]) compared with placebo use (-0.4 [0.8]) (P = .01 comparing distributions). Ecallantide therapy was also associated with a significantly larger mean (SD) treatment outcome score 4 hours after dosing vs placebo use (ecallantide: 53.4 [49.7]; placebo: 8.1 [63.2]; P = .003 comparing distributions). The benefit of ecallantide was apparent within 2 hours after dosing and was maintained through 24 hours after dosing. The safety profile was similar between the treatment groups.

CONCLUSION

Ecallantide appears to be an effective and safe treatment for acute attacks of HAE.

Hereditary angioedema: an update on available therapeutic options

There is no cure for hereditary angioedema (HAE). Therapeutic approaches consist of symptomatic therapy for acute attacks, short-term prophylaxis before surgery, and long-term prophylaxis for those with frequent and severe attacks. In Germany, C1-INH concentrate and icatibant are licensed for acute therapy. C1-INH concentrate, which is obtained from human plasma, is administered intravenously to restore the deficient C1-INH activity. This therapy, which has been available for decades, is effective and well-tolerated. Batch documentation is required by German law. The synthetic decapeptide icatibant is administered subcutaneously. It competes with bradykinin, the responsible inducer of edema formation, for binding to the bradykinin B2 receptor. Icatibant is also effective and well-tolerated, even on repeated administration. An additional human C1-inhibitor, a recombinant human C1-inhibitor and the recombinant inhibitor of kallikrein ecallantide are currently under development. There are no licensed treatment options available in Germany for long- and short-term prophylaxis. Androgen derivatives are established in long-term prophylaxis. However, they are associated with many adverse effects, some of which are severe. Many drug interactions also limit their use. They are contraindicated in pregnancy, lactation, for children and in cases of prostate cancer. Antifibrinolytics have fewer adverse effects but are also less effective than androgens. They are contraindicated in thromboembolic disease and impaired vision. If androgen therapy has too negative an effect on quality of life, it may be worth reducing the dose or discontinuing therapy entirely and treating attacks with acute therapy.

Upper airway considerations in hereditary angioedema

PURPOSE OF REVIEW

The purpose of the present review is to outline the clinical aspects and management of the upper airway involvement in the patients suffering from hereditary angioedema.

RECENT FINDINGS

Molecular mechanisms of hereditary angioedema reviewed in the literature conclude that it is an autosomal dominant disorder, characterized by the deficiency of C1 inhibitor due to mutations of its gene (SERPING). Hereditary angioedema manifests as episodes of localized swelling in any site of the body from skin, gastrointestinal tract to the upper airway, where it is severe and life-threatening. The age of onset, frequency of attacks and the factors triggering upper airway swelling in hereditary angioedema are variable among different patients. Acute laryngeal edema should be managed in emergency with monitoring of airway patency. To avoid airway obstruction, therapy should begin early either with current treatment (C1 inhibitor concentrate) or with new drugs developed recently. In patients with recurrent upper airway swelling attacks, long-term prophylaxis is recommended.

CONCLUSION

The use of old and new treatment in acute attacks as well as in prophylaxis (long and short-term) has changed the outcome of patients with hereditary angioedema who present upper airway swelling.

Hereditary angioedema: New therapeutic options for a potentially deadly disorder

Although the biochemistry of hereditary angioedema (HAE) is fairly well understood today, the lag in diagnosis of a decade or more suggests that clinicians have low awareness of this disease. This lag in diagnosis and hence treatment certainly stems from the rarity and complexity of the presentation which can be easily mistaken for allergic and non-allergic reactions alike. The symptoms of the disease include acute swelling of any or multiple parts of the body. The attacks may be frequent or rare, and they may vary substantially in severity, causing stomach discomfort or periorbital swelling in mild cases and hypovolemic shock due to abdominal fluid shift or asphyxiation in the most severe cases. Given that these patients are at significant risk for poor quality of life and death, greater awareness of this disease is needed to ensure that newly available, effective medications are used in these patients. These new medications represent significant advances in HAE therapy because they are targeted at the plasma cascades implicated in the pathophysiology of this disease. The clinical presentation of HAE, overlapping symptoms with other angioedemas, and available therapies are reviewed.

Ecallantide: its pharmacology, pharmacokinetics, clinical efficacy and tolerability

Ecallantide (Kalbitor, Dyax Corporation) is a highly specific recombinant plasma kallikrein inhibitor developed for treatment of hereditary angioedema (HAE). Advantages of this agent over plasma-derived treatments are that it poses no risk of viral contamination, is highly selective, has a quick onset of action and can be administered subcutaneously. In clinical trials, ecallantide appears to be a safe and effective drug useful for the treatment of HAE patients suffering from an acute attack. Ecallantide was found to be superior compared with placebo in relieving symptoms, decreasing the severity of attacks and shortening the duration of attacks. The primary safety concern appears to be related to hypersensitivity reactions. Phase IV postmarketing surveillance studies to monitor the incidence of these reactions will be implemented by the company now that the drug has been US FDA approved.

Clinical review of hereditary angioedema: diagnosis and management

Hereditary angioedema (HAE) is caused by a deficiency in C1 esterase inhibitor and is characterized by sudden attacks of edema associated with discomfort and pain. The disease places patients at risk for disability and death if left untreated. Symptom severity and frequency can be extremely variable even among affected members of the same family. Attacks are not associated with inflammation or allergy, with most occurring secondary to trauma or stress. Swelling can affect any part of the body or multiple sites at once. Commonly affected areas include the extremities, genitalia, trunk, gastrointestinal tract, face, and larynx. Swelling typically worsens over 24 to 36 hours and resolves within 48 hours in less severe cases. Attacks result in 15,000 to 30,000 emergency department visits each year. Many of these emergency cases will undergo unnecessary surgeries or medical procedures due to misdiagnosis. The hallmarks of HAE--recurrent episodes of swelling without urticaria, a family history of HAE, first attack in childhood, and worsening at puberty--can be identified by a thorough family history, and the diagnosis can be confirmed by laboratory studies. Nevertheless, diagnosis may be delayed by 2 decades. We review available therapies and clinical characteristics that will both help clinicians diagnose HAE and distinguish among emergencies and nonemergency cases.

The effect of long-term danazol prophylaxis on liver function in hereditary angioedema-a longitudinal study

BACKGROUND

Danazol is a drug most widely used for the prophylaxis of hereditary angioedema resulting from the deficiency of the C1-inhibitor. Potential hepatotoxic or liver tumor-inducing side effects of long-term danazol prophylaxis have been investigated during the follow-up of hereditary angioedema patients.

METHODS

Characteristic parameters of liver function (including bilirubin, GOT, GPT, gammaGT, total protein, ALP, LDH), as well as findings of viral serology screens and abdominal ultrasonography-determined during years 0 and 5 of follow-up of patient groups taking/not taking danazol-have been reviewed and analyzed comparatively.

RESULTS

From a population of 126 hereditary angioedema patients, 46 subjects taking danazol and another 46 not taking danazol fulfilled the inclusion criteria. Longitudinal follow-up did not reveal any clinically relevant difference between the liver function parameters determined in years 0 and 5 in the two groups. Abdominal ultrasound did not detect neoplastic or other potentially treatment-related alterations of the liver parenchyma. There were no discontinuations of treatment during the study.

CONCLUSIONS

Our results clearly suggest that, administered at the lowest effective dose, danazol does not induce liver injury in hereditary angioedema patients.

Current and emerging management options for hereditary angioedema in the US

Hereditary angioedema (HAE) is a rare disorder characterized by recurrent attacks of swelling that may involve multiple anatomical locations. In the majority of patients, it is caused by a functional or quantitative defect in the C1 inhibitor (C1-INH), which is an important regulator of the complement, fibrinolytic, kallikrein-kinin and coagulation systems. Standard treatments used for other types of angioedema are ineffective for HAE. Traditional therapies for HAE, including fresh frozen plasma, epsilon-aminocaproic acid and danazol, may be well tolerated and effective in some patients; however, there are limitations both in their safety and efficacy. Several novel therapies have completed phase III trials in the US, including: (i) plasma-derived C1-INH replacement therapies (Berinert P and Cinryze); (ii) a recombinant C1-INH replacement therapy (conestat alfa; Rhucin); (iii) a kallikrein inhibitor (ecallantide [DX-88]); and (iv) a bradykinin-2-receptor antagonist (icatibant). Both Berinert P and Cinryze are reported to have excellent efficacy and safety data from phase III trials. Currently, only Cinryze has been approved for prophylactic use in the US. US FDA approval for other novel agents to treat HAE and for the use of Cinryze in the treatment of acute attacks is pending.

Hereditary angiodema: a current state-of-the-art review, IV: short- and long-term treatment of hereditary angioedema: out with the old and in with the new?

OBJECTIVE

To provide a context to understand the opportunity for novel therapeutic modalities to transform the treatment of hereditary angioedema (HAE).

DATA SOURCES

MEDLINE and PubMed were searched to identify studies involving current treatment of HAE in the United States.

STUDY SELECTION

Studies were selected based on their relevance to the treatment of HAE.

RESULTS

The current HAE treatment strategy is far from satisfactory, and its limitations create an unmet clinical need. Current prophylactic treatment exposes patients with HAE to significant risk of adverse effects, and the efficacy of prophylactic treatment, although generally good, is far from perfect.

CONCLUSIONS

No specific treatment is currently available in the United States for acute HAE attacks that will reliably work, resulting in a significant unmet clinical need. The emergence of several promising drugs for the treatment of HAE attacks is, thus, an extraordinarily important development in the management of these patients.