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

Angioedema due to Acquired C1-Inhibitor Deficiency Associated With Monoclonal Gammopathies of Undetermined Significance Characteristics of a French National Cohort

BACKGROUND

No specific description of monoclonal gammopathies of undetermined significance (MGUS)-associated angioedema due to acquired C1 inhibitor deficiency (AAE-C1-INH) has been reported yet.

OBJECTIVE

To describe the biological and clinical characteristics, evolution, and response to treatment of MGUS-associated AAE-C1-INH.

MATERIALS AND METHODS

We conducted a French national retrospective observational study on MGUS-associated acquired angioedema spanning a 30-year period.

RESULTS

Forty-one patients with MGUS-associated AAE-C1-INH at diagnosis were included; 68% displayed anti-C1-INH antibodies. The monoclonal component was an IgM in 24 patients, IgG in 11, and IgA in 6 patients. The mean age at first angioedema attack was 63 years (standard deviation [SD] = 13 years) and at diagnosis 66 years (SD = 11 years). A total of 88% patients benefited from acute attack treatments, and 77% from long-term prophylaxis, either danazol, tranexamic acid, or lanadelumab. Median follow-up was 7 years, during which 14 patients (33%) evolved into well-defined malignant hemopathies. Fifty percent of patients were given a hematological treatment, either rituximab alone, indicated by recurrent attacks of angioedema in patients with AAE-C1-INH with anti-C1-INH antibodies, or validated combinations of chemotherapies, indicated by evolution into a lymphoma in 7 patients and a myeloma in 3 patients. Fifteen patients (35%) were in clinical complete remission of angioedema at last visit, of whom 60% had an undetectable serum monoclonal immunoglobulin.

CONCLUSIONS

Complete remission of AAE-C1-INH is correlated to complete remission of the underlying hematological malignancy, as defined by an undetectable serum monoclonal immunoglobulin. In our MGUS-associated acquired angioedema cohort, we recorded an incidence of evolution into hematological malignancy of 4% per patient-year. It is therefore crucial to conduct full hematological workup during follow-up at an annual rate, and earlier if AAE relapses or if acute attack frequency increases.

Unveiling the Complexities of Hereditary Angioedema

Hereditary angioedema (HAE) is a rare and potentially life-threatening genetic disorder, constituting approximately 2% of all clinical cases of angioedema, with a global prevalence estimated between 1 in 50,000 and 1 in 150,000 individuals. The condition affects individuals of all genders and ethnic backgrounds without significant variation. HAE is classified into three types. Type I HAE, which accounts for 85% of cases, is characterized by a deficiency of the C1 esterase inhibitor (C1-INH) gene. Type II HAE, making up 15% of cases, involves a dysfunctional C1-INH. Type III HAE, which represents about 5% to 10% of cases, is often estrogen-dependent and although several mutations have been identified, it typically involves normal C1-INH activity. Despite the differences in C1-INH functionality, all three types of HAE manifest with similar clinical symptoms. HAE leads to recurrent episodes of non-pruritic angioedema, which occurs in the absence of urticaria. Breakthroughs in understanding HAE pathophysiology have revolutionized treatment, leading to the development of highly targeted therapies for both acute management and long-term prevention. Meanwhile, cutting-edge advancements in omics technologies are unlocking new possibilities for biomarker discovery, paving the way for more precise diagnoses and personalized treatment strategies that could significantly enhance patient outcomes. This review will delve into the intricate pathophysiology, diverse clinical presentations, and diagnostic challenges of HAE while exploring emerging biomarkers and innovative approaches to therapeutic management and prevention strategies. Additionally, it will underscore the vital importance of screening family members of affected individuals, even when symptoms are not present.

Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency

BACKGROUND

Angioedema (AE) due to acquired C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) is related to excessive consumption of C1-INH or to anti-C1-INH antibodies, and is frequently associated with lymphoproliferative syndromes or monoclonal gammopathies. Standard of care for prophylactic treatment in this condition is not established. Rituximab may be effective to prevent attacks, especially if the lymphoid hemopathy is controlled, but data are scarce.

OBJECTIVE

To evaluate efficacy of rituximab in AAE-C1-INH.

METHODS

A retrospective multicenter study was carried out in France, including patients with AAE-C1-INH treated with rituximab between April 2005 and July 2019.

RESULTS

Fifty-five patients with AAE-C1-INH were included in the study, and 23 of them had an anti-C1-INH antibody. A lymphoid malignancy was identified in 39 patients, and a monoclonal gammopathy in 9. There was no associated condition in 7 cases. Thirty patients received rituximab alone or in association with chemotherapy (n = 25). Among 51 patients with available follow-up, 34 patients were in clinical remission and 17 patients had active AE after a median follow-up of 3.9 years (interquartile range, 1.5-7.7). Three patients died. The presence of anti-C1-INH antibodies was associated with a lower probability of AE remission (hazard ratio, 0.29 [95% CI, 0.12-0.67]; P = .004). Relapse was less frequent in patients with lymphoma (risk ratio, 0.27 [95% CI, 0.09-0.80]; P = .019) and in patients treated with rituximab and chemotherapy (risk ratio, 0.31 [95% CI, 0.12-0.79]; P = .014).

CONCLUSIONS

Rituximab is an efficient and well-tolerated therapeutic option in AE, especially in lymphoid malignancies and in the absence of detectable anti-C1-INH antibodies.

Acquired Angioedema Due to C1-Inhibitor Deficiency (AAE-C1-INH)-A Bicenter Retrospective Study on Diagnosis, Course, and Therapy

BACKGROUND

Acquired angioedema with C1-inhibitor deficiency (AAE-C1-INH) is a rare condition resembling hereditary angioedema (HAE), but with late onset and low C1-inhibitor (C1-INH) due to consumption potentially caused by autoimmune diseases and mainly lymphatic malignancies. Being about 10-fold rarer than HAE, there is limited knowledge and no licensed therapy.

OBJECTIVE

To report clinical and biological data from a newly described population of 20 patients with AAE-C1-INH assessing diagnostic delay, AAE-C1-INH:HAE-ratio, underlying conditions, and therapeutic management in Germany.

METHODS

Retrospective data analysis of 20 patients from 2 angioedema centers in southern Germany.

RESULTS

Median age at symptoms' onset was 64 years (60% females), with predominant swellings of the face (85%) and low levels for C1-INH in almost all patients. The ratio AAE-C1-INH:HAE was 1:9.7. From symptoms' onset to diagnosis of AAE-C1-INH, the median delay was 7.5 months, and between AAE-C1-INH symptoms' onset and diagnosis of the underlying hematological condition (n = 9) it was 4 months (median). Four patients had a history of solid neoplasm, 1 had a papillary thyroid carcinoma as the only potential cause for AAE-C1-INH, with treatment of the malignancy resulting in resolution of AAE-C1-INH. All the symptomatic patients were treated with off-label on-demand icatibant subcutaneously or C1-INH concentrate intravenously, and 6 severely affected patients needed off-label long-term prophylaxis with good symptom control.

CONCLUSIONS

AAE-C1-INH is characterized by late-onset swellings mainly involving the face and low C1-INH levels. Diagnostic delay for AAE-C1-INH is further decreasing despite being about 10-fold rarer than HAE. Patients severely affected without underlying condition or no indication for treatment could benefit from off-label therapy.

A Retrospective Analysis of Long-Term Prophylaxis with Berotralstat in Patients with Hereditary Angioedema and Acquired C1-Inhibitor Deficiency-Real-World Data

Hereditary angioedema (HAE) and acquired C1-inhibitor deficiency (AAE-C1-INH) are orphan diseases. Berotralstat is a recently licensed long-term prophylaxis (LTP) and the first oral therapy for HAE patients. No approved therapies exist for AAE-C1-INH patients. This study is the first to report real-world clinical data of patients with AAE-C1-INH and HAE who received Berotralstat. All patients treated with Berotralstat were included in this retrospective, bi-centric study. Data was collected from patients' attack calendars and the angioedema quality of life (AE-QoL) and angioedema control test (AECT) questionnaires before treatment, and at 3, 6, and 12 months after treatment and was then analyzed. Twelve patients were included, 3 patients with AAE-C1-INH, 7 patients with HAE type I, and 2 patients with HAE-nC1-INH. One patient (HAE I) quit treatment. Berotralstat was associated with fewer attacks in all groups. After 6 months of treatment, a median decrease of attacks per month was noted for HAE type I patients (3.3 to 1.5) and AAE-C1-INH patients (2.3 to 1.0). No aerodigestive attacks were noted for AAE-C1-INH patients. For HAE-nC1-INH patients, a mean decrease from 3.8 to 1.0 was noted (3 months). For HAE I patients, the total AE-QoL lowered a mean of 24.1 points after 6 months, for HAE-nC1-HAE patients 8.0 points, and for AAE-C1-INH patients 13.7 points. AECT scores increased for HAE I patients (mean: 7.1), HAE-nC1-INH patients (9.0), and AAE-C1-INH patients (4.2) after 6 months. Patients with HAE, HAE-nC1-INH, and AAE-C1-INH treated with Berotralstat showed reduced angioedema attacks and improved AE-QoL and AECT scores.

Real-world experience of hereditary angioedema (HAE) in Mexico: A mixed-methods approach to describe epidemiology, diagnosis, and treatment patterns

Introduction and objectives

Due to the lack of structured and systematic information available, the aim of this study was to describe the epidemiology, diagnosis, healthcare processes, and treatment patterns of hereditary angioedema (HAE) in Mexico. To achieve this, different data sources were consulted regarding medical literature, structured health system databases, and angioedema-specialized physicians (AEP) opinion regarding HAE.

Material and methods

A mixed methods approach was conducted in 4 phases: I) systematic literature review (SLR) and meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines; II) review of national health system (NHS) databases and systematic reports; III) physician survey; and IV) an epidemiologic model. ICD 10 D84.1 encoded records from the NHS were used to estimate the number of patients with HAE attended and treated during 2019. A survey was implemented to increase understanding of the clinical profile and treatments used.

Results

A prevalence rate of 0.9/50 000 inhabitants was estimated for 2019. In the same year, an estimated 317 HAE type 1 patients were recorded in the NHS, aged ≥11 years old. The most frequent clinical symptoms were cutaneous edema (67.5%) and abdominal pain (47.9%). A severe episode with laryngeal edema appeared in 27.5% of cases. Acute episodes were mainly moderate to severe (77.0%), with an annual per capita frequency of emergency visits of 7.6 patient-year (range 1-12/patient-year). The main reasons for hospitalization corresponded to laryngeal facial, tongue, and abdominal edemas, representing 73.3% of annual ICD 10 D84.1 reported hospitalizations. The main treatments that patients with HAE received were fresh frozen plasma for acute attacks and danazol for short-term prophylaxis (STP).

Conclusions

Despite efforts to make HAE visible, according to this study, cases recognized and treated in the NHS represent only 16.6% of the estimated prevalence.

Chronic Urticaria and Angioedema: Masqueraders and Misdiagnoses

Chronic urticaria is a common condition presenting with intensely pruritic wheals. Although individual lesions resolve within 24 hours, by definition, chronic urticaria lasts for a duration of at least 6 weeks. Both spontaneous and inducible forms exist. In the spontaneous variant, chronic urticaria occurs in the absence of clearly identifiable triggers. In chronic inducible urticaria, specific triggers may include dermatographism, cholinergic (heat), cold, exercise, delayed pressure, and solar. Extensive laboratory evaluation for chronic spontaneous urticaria is not required unless indicated by clinical history or physical examination. Angioedema describes sudden onset of localized edema involving the deep layers of the skin and submucosal tissues. It can be seen in isolation or in conjunction with chronic urticaria. Angioedema typically resolves slower than wheals, taking up to 72 hours or longer. Histamine- and bradykinin-mediated forms exist. Both chronic urticaria and angioedema have many mimics, and a broad range of differential diagnoses should be considered. Importantly, an incorrect diagnosis may have significant implications for the additional investigation, treatment, and prognosis of the affected patient. The aim of this article is to discuss the characteristics of chronic urticaria and angioedema, and an approach to the investigation and diagnosis of their mimics.

Hereditary Angioedema

Hereditary angioedema (HAE) is a rare autosomal dominant genetic disorder that usual results from a decreased level of functional C1-INH and clinically manifests with intermittent attacks of swelling of the subcutaneous tissue or submucosal layers of the respiratory or gastrointestinal tracts. Laboratory studies and radiographic imaging have limited roles in evaluation of patients with acute attacks of HAE except when the diagnosis is uncertain and other processes must be ruled out. Treatment begins with assessment of the airway to determine the need for immediate intervention. Emergency physicians should understand the pathophysiology of HAE to help guide management decisions.

Angioedema Due to Acquired Deficiency of C1-Inhibitor: A Cohort Study in Spain and a Comparison With Other Series

BACKGROUND

Data on acquired angioedema due to C1-inhibitor deficiency (C1-INH-AAE) from 4 European countries (France, Italy, Germany, and Hungary) were recently published.

OBJECTIVE

To report data from a group of 50 patients with acquired C1-INH deficiency from Spain, of whom 46 had angioedema, and compare them with other European series.

METHODS

We performed a retrospective observational study of 46 patients with C1-INH-AAE and 4 asymptomatic patients. Clinical and biological characteristics and associated diseases were assessed and compared with other European series.

RESULTS

Women accounted for 73.9% of cases. The prevalence of C1-INH-AAE related to hereditary forms was 1/10.1. Overall, 8.7% patients were aged <40 years. Diagnostic delay was 1.1 years. Angioedema mainly affected the face (91.3%), followed by the oropharynx (63%), extremities (50%), and abdomen (37%). Only 1 patient underwent orotracheal intubation. Erythema marginatum was present in 1 patient. A hematologic disorder was recorded in 50% of patients. Angioedema preceded all benign conditions, mostly monoclonal gammopathy of undetermined significance, but appeared very close to or after malignant hematologic diseases (median, 2.2 and 0.29 years). Autoimmune diseases were associated in 50% (autoimmune thyroiditis, 21.5%; systemic lupus erythematosus, 10.9%). Half of them coexisted with hematologic disorders. Anti-C1-INH antibodies were found in 67% of tested patients and were not related to the associated disease. Long-term prophylaxis was necessary in 52.2%, most of whom responded to tranexamic acid.

CONCLUSIONS

This study emphasizes the possibility of C1-INH-AAE in patients younger than 40 and in autoimmune diseases other than systemic lupus erythematosus such as autoimmune thyroiditis.

Hereditary Angioedema

Hereditary angioedema (HAE) is a rare autosomal dominant genetic disorder that usual results from a decreased level of functional C1-INH and clinically manifests with intermittent attacks of swelling of the subcutaneous tissue or submucosal layers of the respiratory or gastrointestinal tracts. Laboratory studies and radiographic imaging have limited roles in evaluation of patients with acute attacks of HAE except when the diagnosis is uncertain and other processes must be ruled out. Treatment begins with assessment of the airway to determine the need for immediate intervention. Emergency physicians should understand the pathophysiology of HAE to help guide management decisions.

Differences and Similarities in the Mechanisms and Clinical Expression of Bradykinin-Mediated vs. Mast Cell-Mediated Angioedema

Angioedema (AE), transient localized swelling due to extravasated fluid, is commonly classified as mast cell mediator-induced, bradykinin-mediated or of unknown cause. AE often occurs more than once, and it is these recurrent forms of AE that are challenging for patients and physicians, and they are the ones we focus on and refer to as AE in this review. Since effective treatment depends on the causative mediator, reliable and early diagnosis is essential. Although their clinical presentations bear similarities, many forms of angioedema exhibit specific patterns of clinical appearance or disease history that may aid in diagnosis. Here, we describe the most common differences and similarities in the mechanisms and clinical features of bradykinin-mediated and mast cell mediator-induced types of angioedema. We first provide an overview of the diseases that manifest with mast cell mediator-induced versus bradykinin-mediated angioedema as well as their respective underlying pathogenesis. We then compare these diseases for key clinical features, including angioedema location, course and duration of swelling, attack frequency, prevalence and relevance of prodromal signs and symptoms, triggers of angioedema attacks, and other signs and symptoms including wheals, age of onset, and duration. Our review and comparison of the clinical profiles of different types of angioedema incorporate our own clinical experience as well as published information. Our aim is to highlight that mast cell mediator-induced and bradykinin-mediated angioedema types share common features but are different in many aspects. Knowledge of the differences in underlying pathomechanisms and clinical profiles between different types of angioedema can help with the diagnostic approach in affected patients and facilitate targeted and effective treatment.

The Global Registry for Hereditary Angioedema due to C1-Inhibitor Deficiency

Hereditary angioedema (HAE) is a rare condition, mostly due to genetic deficiency of complement C1 inhibitor (C1-INH). The rarity of HAE impedes extensive data collection and assessment of the impact of certain factors known to affect the course of this disabling and life-threatening disease. Establishing a global registry could assist to overcome such issues and provides valuable patient data from different countries. The HAE Global Registry is a disease-specific registry, with web-based electronic support, where data are provided by physicians and patients through a dedicated application. We collected data between January 1, 2018, and August 31, 2020. Data on 1297 patients from 29 centers in 5 European countries were collected. At least one attack was recorded for 497 patients during the study period. Overall, 1182 patients were diagnosed with HAE type 1 and 115 with type 2. At the time of database lock, 389 patients were taking long-term prophylactic medication, 217 of which were on danazol. Most recorded attacks affected the abdomen, were generally moderate in severity, and occurred in patients who were not on prophylactic treatment (70.6%, 6244/8848). The median duration of attacks was 780 min (IQR 290-1740) in patients on prophylactic medication and 780 min (IQR 300-1920) in patients not on continuous prophylactic medication. In conclusion, the establishment of a registry for C1-INH-HAE allowed collection of a large amount of data that may help to better understand the clinical characteristics of this disease. This information may enhance patient care and guide future therapeutic decisions.

Managing Chronic Urticaria and Recurrent Angioedema Differently with Advancing Age

Angioedema and urticaria affect people of all ages. Accurate diagnosis and optimum management is essential for healthy aging. Older people continue to experience mast cell-mediated urticaria and angioedema, with a higher prevalence of autoimmune and a lower prevalence of autoallergic disease. Bradykinin-mediated angioedemas are more common in the elderly because of their association with angiotensin-converting enzyme inhibitor (ACEI) treatment. Acquired C1-inhibitor deficiency, another bradykinin-mediated angioedema, occurs predominantly in older people, whereas hereditary angioedema due to C1-inhibitor deficiency continues to cause symptoms, even in old age. Drug-induced angioedemas disproportionately affect older people, the most frequent users of ACEIs, aspirin, and nonsteroidal anti-inflammatory drugs. Accurate diagnosis and targeted treatment prevent unnecessary morbidity and mortality. Second-generation antihistamines with omalizumab if required are effective and well tolerated in older people with mast cell-mediated urticaria. For bradykinin-mediated angioedemas, these drugs are ineffective. C1-inhibitor replacement or blockade of kallikrein or the bradykinin B2 receptor of the contact pathway is required to treat hereditary angioedema and may be considered in other bradykinin-mediated angioedemas, if supportive treatment is insufficient. For aspirin-related angioedema and urticaria, alternative medications or, exceptionally, desensitization may be required.

A follow-up survey of patients with acquired angioedema due to C1-inhibitor deficiency

BACKGROUND

Acquired angioedema due to C1-inhibitor deficiency (C1-INH-AAE) is a rare form of bradykinin-mediated angioedema. It is diagnosed by complement testing; its treatment consists of the management of angioedema (AE) attacks and of underlying disease.

OBJECTIVE

Evaluate the results of the clinical follow-up of patients with C1-INH-AAE.

METHODS

Between 1999 and 2020, 3938 patients with angioedema were evaluated, and 17 diagnosed with acquired C1-INH deficiency were followed-up.

RESULTS

Mean age of the 17 patients was 61 years at diagnosis. In 33%, ACE inhibitors provoked AE attacks. Autoantibodies against C1-INH were detected in 10 patients at diagnosis and in a further patient during follow-up. The AE attacks involved the skin in 70.6%, the upper airways in 41.2% and the tongue/lip in 52.9% of patients. Twelve of the 17 patients had an underlying condition, mainly (n = 11) lymphoproliferative disease. In 10 patients diagnosed with a haematological disorder, AAE symptoms preceded the onset of the latter. One patient has not experienced an AE attack since diagnosis. Twelve patients were treated for angioedema attacks, and 32% of the attacks required acute treatment. PdC1-INH was used to relieve AE attacks, and rituximab for the treatment of underlying disease (in six patients). Six patients had multiple AE attacks before any treatment. The symptom-free period increased in five patients after the on-demand administration of pdC1-INH concentrate and following treatment of the underlying disease in two patients.

CONCLUSION

Early diagnosis of C1-INH-AAE and underlying disease is indispensable to reduce disease burden by introducing appropriate, individualized treatment and regular follow-up.

Hereditary angioedema: an update on causes, manifestations and treatment

Hereditary angioedema is a rare genetic disorder caused by deficiency of C1 esterase inhibitor (C1-INH) and characterized by recurrent episodes of severe swelling that affect the limbs, face, intestinal tract and airway. Since laryngeal oedema can be life-threatening as a result of asphyxiation, correct diagnosis and management of hereditary angioedema is vital. Hereditary angioedema attacks are mediated by bradykinin, the production of which is regulated by C1-INH. Hereditary angioedema therapy relies on treatment of acute attacks, and short- and long-term prophylaxis. Acute treatment options include C1-INH concentrate, icatibant and ecallantide. Self-administration of treatment is recommended and is associated with increased quality of life of patients with hereditary angioedema. Advances in diagnosis and management have improved the outcomes and quality of life of patients with hereditary angioedema.

Angioedema due to acquired C1-inhibitor deficiency: spectrum and treatment with C1-inhibitor concentrate

Background

Acquired angioedema due to C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) is a serious condition that may result in life-threatening asphyxiation due to laryngeal edema. It is associated with malignant B-cell lymphoma and other disorders. The purpose of this study was to describe the characteristics and associated disorders of patients with AAE-C1-INH and assess the efficacy of plasma-derived C1-INH concentrate (pdC1-INH) in the treatment of AAE-C1-INH. Forty-four patients with AAE-C1-INH from the Angioedema Outpatient Service of Mainz were assessed for associated disorders. In 32 of these patients, the duration of swelling attacks was measured before and after treatment with pdC1-INH (Berinert® (CSL Behring, Marburg, Germany)). The time between injection and complete resolution of symptoms and treatment effectiveness was provided by the patients.

Results

The following underlying disorders were present: monoclonal gammopathy of undetermined significance (47.7%), non-Hodgkin lymphoma (27.3%), anti-C1-INH autoantibodies alone (11.4%), and other conditions (4.5%). In 9.1% patients, no associated disorder could be found. AAE-C1-INH led to the detection of lymphoma in 75% of patients with the malignancy. Treatment with pdC1-INH shortened attacks by an average (SD) 54.4 (± 32.8) hours (P < 0.0001). The earlier the attack was treated, the shorter the time between injection and resolution of symptoms (P = 0.0149). A total of 3553 (97.7%) of the 3636 attacks were effectively treated with pdC1-INH as assessed by the patient. The mean (SD) dose per-attack was 787 (± 442) U. pdC1-INH was effective in 1246 (93.8%) of 1329 attacks in 8 patients with anti-C1-INH autoantibodies and in 344 (99.4%) of 346 attacks in 6 patients without autoantibodies. The average (SD) dose per effectively treated attack was 1238.4 (± 578.2) U in patients with anti-C1-INH autoantibodies and 510.2 (± 69.1) U in patients without autoantibodies.

Conclusions

pdC1-INH is highly effective in treating AAE-C1-INH patients and is also effective in the vast majority of attacks in patients with anti-C1-INH autoantibodies. It is fast-acting and reduces attack duration.

Nine year follow-up of a rare case of angioedema due to acquired C1-inhibitor deficiency with late onset and good response to attenuated androgen

Background

Angioedema due to acquired deficiency of C1-inhibitor (C1-INH-AAE) is a rare disease sharing some clinical and laboratory similarities with hereditary angioedema, but with late onset and no positive family history. The underlining cause may be malignant or due to autoimmune diseases, but some cases remain idiopathic.

Case presentation

We report a case of a 75 year old woman suffering from recurrent episodes of angioedema since the age of 66, considered first induced by treatment with angiotensin-converting-enzyme inhibitors (ACEI). She continued to have angioedema attacks during 6 years after discontinuation of ACEI, until evaluation in our clinic in 2014, when C1 inhibitor esterase (C1-INH) deficiency was confirmed. The extended medical evaluation for inflammatory, allergic, autoimmune and neoplasic diseases was negative. C1-INH and complement fraction C4 plasma levels were significantly decreased at all measurements, but no diagnostic criteria for diseases known to induce C1-INH deficiency could be found. We first initiated daily prophylactic treatment with tranexamic acid, with no amelioration after 3 months. During the last and most severe attack, with the first facial and laryngeal edema, we have switched to attenuated androgen danazol. The evolution was very good, with prompt remission of angioedema and significant increase of C1-INH and C4 plasma levels after 2 weeks of daily danazol use. She completed 3 years of continuous treatment with low daily maintenance dose of danazol (ongoing), with no angioedema attack. We closely monitored C1-INH and C4 plasma levels, possible danazol side effects and any signs suggesting late onset of C1-INH deficiency causal disease.

Conclusion

We reported a particular case of rare angioedema due to acquired deficiency of C1-inhibitor, which has no clear cause after long follow-up, but good response to attenuated androgen. We concluded that the awareness of angioedema due to C1-INH deficiency should be increased within medical community and therapeutic options should be more clearly indicated and available for all diagnosed cases.

Real-world outcomes in hereditary angioedema: first experience from the Icatibant Outcome Survey in the United Kingdom

Background

Hereditary angioedema (HAE) is a potentially life-threatening, bradykinin-mediated disease, often misdiagnosed and under-treated, with long diagnostic delays. There are limited real-world data on best-practice management of HAE in the UK.

Objectives

To characterize the clinical profile, management and outcomes of patients with HAE type I and II from three specialist centres in the UK using data from the Icatibant Outcome Survey (IOS; Shire, Zug, Switzerland), an international observational study monitoring safety and effectiveness of icatibant, a selective bradykinin B2 receptor antagonist.

Methods

We performed retrospective analyses of IOS data for patients with HAE type I and II from three centres in the UK and compared UK data with pooled IOS data from 10 countries (48 centres).

Results

Analyses included 73 UK and 579 non-UK patients with HAE type I or II. Median diagnostic delay was 6.2 and 5.9 years, respectively. Analysis of data collected from February 2008 to July 2016 included 286 icatibant-treated attacks in 58 UK patients and 2553 icatibant-treated attacks in 436 non-UK patients (median of 3.0 attacks per patient in both groups). More attacks were treated by icatibant self-administration in UK patients (95.8%) than in non-UK patients (86.8%, p < 0.001). Time to icatibant treatment, time to resolution and attack duration were not significantly different in the UK versus non-UK patients.

Conclusion

UK patients from the specialist centres studied report similar diagnostic delay and similar icatibant treatment outcomes to their non-UK counterparts. However, improvements in the timely diagnosis of HAE are still required.

Trial registration ClinicalTrials.gov NCT01034969

Optimum Use of Acute Treatments for Hereditary Angioedema: Evidence-Based Expert Consensus

Acute treatment of hereditary angioedema due to C1 inhibitor deficiency has become available in the last 10 years and has greatly improved patients’ quality of life. Two plasma-derived C1 inhibitors (Berinert and Cinryze), a recombinant C1 inhibitor (Ruconest/Conestat alpha), a kallikrein inhibitor (Ecallantide), and a bradykinin B2 receptor inhibitor (Icatibant) are all effective. Durably good response is maintained over repeated treatments and several years. All currently available prophylactic agents are associated with breakthrough attacks, therefore an acute treatment plan is essential for every patient. Experience has shown that higher doses of C1 inhibitor than previously recommended may be desirable, although only recombinant C1 inhibitor has been subject to full dose–response evaluation. Treatment of early symptoms of an attack, with any licensed therapy, results in milder symptoms, more rapid resolution and shorter duration of attack, compared with later treatment. All therapies have been shown to be well-tolerated, with low risk of serious adverse events. Plasma-derived C1 inhibitors have a reassuring safety record regarding lack of transmission of virus or other infection. Thrombosis has been reported in association with plasma-derived C1 inhibitor in some case series. Ruconest was associated with anaphylaxis in a single rabbit-allergic volunteer, but no further anaphylaxis has been reported in those not allergic to rabbits despite, in a few cases, prior IgE sensitization to rabbit or milk protein. Icatibant is associated with high incidence of local reactions but not with systemic effects. Ecallantide may cause anaphylactoid reactions and is given under supervision. For children and pregnant women, plasma-derived C1 inhibitor has the best evidence of safety and currently remains first-line treatment.

Complement as a diagnostic tool in immunopathology

The complement system is a complex and autoregulated multistep cascade at the interface of innate and adaptive immunity. It is activated by immune complexes or apoptotic cells (classical pathway), pathogen-associated glycoproteins (lectin pathway) or a variety of molecular and cellular surfaces (alternative pathway). Upon activation, complement triggers the generation of proteolytic fragments that allow the elimination of the activating surface by enhancing inflammation, opsonization, phagocytosis, and cellular lysis. Moreover, complement efficiently discriminates self from non-self surfaces by means of soluble and membrane-bound complement regulators which are critical for innate self-tolerance. Complement deficiency or dysfunction disturb complement homeostasis and give rise to diseases as diverse as bacterial infections, autoimmunity, or renal and neurological disorders. Research on complement-targeted therapies is an expanding field that has already improved the prognosis of severe diseases such as atypical Haemolytic Uremic syndrome or Paroxysmal Nocturnal Haemoglobinuria. Therefore, complement analysis and monitoring provides valuable information with deep implications for diagnosis and therapy. In addition to its important role as an extracellular defense system, it has now become evident that complement is also present intracellularly, and its activation has profound implications for leukocyte survival and function. In this review, we summarize the essential, up-to-date information on the use of complement as a diagnostic and therapeutic tool in the clinics.