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In this randomized, controlled trial, the number of angioedema attacks per month was approximately 75% lower among adults with hereditary angioedema who received a CRISPR-Cas9–based therapy than among those who received placebo.

Hereditary angioedema (HAE) is characterized by recurrent attacks of severe tissue swelling. In the OASIS‐HAE phase 3 study (NCT05139810), donidalorsen, an RNA‐targeted antisense oligonucleotide that reduces prekallikrein production in the liver, significantly reduced HAE attack rates. To characterize the relationship between prekallikrein concentrations and HAE attack rates following donidalorsen and predict the efficacy of potential dosing regimens, an exposure–response model was developed using data from OASIS‐HAE. Simulations were conducted to evaluate the following regimens: 80 mg once every 4 weeks (Q4W), 8 weeks (Q8W), 1 month (Q1M), and 2 months (Q2M), and a switch to Q2M dosing for patients who were attack‐free for 3 months on the Q1M regimen. The relationship between prekallikrein concentrations and HAE attack rates was well characterized by a sigmoidal Emax (maximum effect) model with baseline attack rate and baseline prekallikrein concentration included as covariates. The average prekallikrein concentration estimated to result in a 90% reduction in attack rate (EC10) was 47.1 mg/L. Predicted percent reductions in attack rates at steady state were similar for Q4W (84.1%) vs. Q1M (82.9%) and Q8W (72.6%) vs. Q2M (70.2%) dosing. Predicted reductions in attack rate remained similar and clinically meaningful in patients who switched from Q1M to Q2M dosing (94.0% in month 1 and 91.3% in month 2 of the 2‐month dosing interval at steady state). Overall, exposure–response analyses supported the efficacy of Q1M and Q2M dosing and indicated that switching to Q2M dosing could be a viable approach for patients who are attack‐free on the Q1M regimen.

Purpose Hereditary angioedema (HAE) is a rare disorder characterized by highly variable, acute attacks of swelling at various anatomical locations. Clinical measures do not adequately assess the diversity of symptoms characteristic of an attack. Two disease-specific, patient-reported outcome measures were developed to comprehensively capture symptom severity and change: the Treatment Outcome Score (TOS) and the Mean Symptom Complex Severity (MSCS) score. Methods This study comprised a secondary analysis of pooled data from a randomized controlled trial to evaluate the psychometric properties, including reliability and validity, and minimally important difference (MID) of the TOS and MSCS score. Results HAE patients (n = 73) had a mean age of 33 years, and 60% were female. Test-retest evaluation demonstrated moderate to substantial agreement (ICCs = 0.53 for TOS; 0.62 for MSCS score). The TOS and change in MSCS score were moderately to highly correlated with a Global Improvement Measure at 4 h (TOS: r = 0.90; MSCS: r = -0.59). Anchor-and distribution-based analyses suggested that conservative estimates for MID are 30 points for TOS and -0.30 points for 4-h change in MSCS score. Conclusions The psychometric tests performed here provide evidence of the reliability and validity of the TOS and MSCS for evaluating symptom severity and change in HAE patients. The TOS and MSCS score provide an example of measurement methodology that may be used to precisely capture symptom severity and change in a disease characterized by acute attacks.

Background Despite the availability of guidelines for the specific treatment of hereditary angioedema (HAE) attacks, HAE morbidity and mortality rates remain substantial. HAE attacks are a major medical issue requiring specific treatment as well as a considerable socio-economic burden. We report a protocol designed to test whether a dedicated call centre is more effective than usual practice in the management of patients experiencing an HAE attack. Methods/design This prospective, cluster-randomised, single-blind, parallel-group, multicentre trial evaluates the morbidity and consequent socio-economic costs of the management of patients experiencing an HAE attack by a dedicated call centre as compared to usual practice. The trial aims to recruit 200 patients. Patients in the intervention arm are provided with an SOS-HAE card with the call centre’s freephone number that they can access in the case of an attack. The centre’s mission is to provide recommended expert advice on early home treatment. The centre can route the call to a local emergency medical service with competency in HAE management or even arrange for the drugs needed for the specific treatment of an HAE attack to be sent to the emergency department of the local hospital. The primary outcome measure is the number of hospital admissions for an HAE attack. Each patient will be followed up every 2 months for 2 years. The study has been approved by the ethics committee ( Comité de Protection des Personnes d’Ile de France 10 ; registration number: 2012-A00044-39; date of approval: 19 January 2012). Discussion The SOS-HAE protocol has been designed to address the handling of attacks experienced by patients with HAE in the home. The proposed trial will determine whether the setting up of a dedicated call centre is more effective than usual practice in terms of reducing morbidity as given by the numbers of hospital admissions. The results are also anticipated to have important implications in terms of socio-economic costs for both healthcare services and patients. Trial registration ClinicalTrials.gov NCT01679912 .

Hereditary angioedema is a rare genetic disease that may include recurrent attacks of cutaneous angioedema, severe abdominal pain, and airway compromise. Prophylaxis and treatment include C1 inhibitor replacement and inhibition of the kallikrein and bradykinin pathways.

Hereditary angioedema with C1 inhibitor deficiency (HAE-C1-INH) is a rare disorder characterized by recurrent, potentially life-threatening swelling in various parts of the body, including the limbs, face, and airways Current treatments focus primarily on symptomatic relief and the management of acute attacks, without targeting the underlying genetic cause or the dysregulated bradykinin production. Donidalorsen, a novel antisense oligonucleotide, addresses a key driver of HAE-C1-INH by targeting prekallikrein (PKK) to reduce bradykinin levels. This meta-analysis evaluates the efficacy and safety of Donidalorsen versus placebo, focusing on two dosing regimens: 4-week and 8-week intervals. Data from two randomized controlled trials (110 patients) revealed that Donidalorsen significantly reduced the frequency of HAE-C1-INH attacks, with the 4-week regimen showing superior outcomes compared to the 8-week dosing. The 4-week group also experienced fewer moderate or severe attacks and a reduced need for on-demand therapy. Adverse events were comparable between the Donidalorsen and placebo groups. These findings suggest that more frequent dosing may optimize treatment outcomes in HAE-C1-INH.

Hereditary angio-oedema is caused by a heterozygous deficiency of C1 inhibitor. This inhibitor regulates several inflammatory pathways, and patients with hereditary angio-oedema have intermittent cutaneous or mucosal swellings because of a failure to control local production of bradykinin. Swellings typically evolve in several hours and persist for a few days. In addition to orofacial angio-oedema, painless swellings affect peripheries, which causes disfigurement or interference with work and other activities of daily living. Angio-oedema affecting the gastrointestinal tract or abdominal viscera causes severe pain often with vomiting due to oedematous bowel obstruction. About 2% of swellings involve the larynx and can be fatal if untreated. About 50% of patients have laryngeal swellings that are potentially fatal despite prophylaxis. In this Seminar we review the clinical features, diagnosis, and management of hereditary angio-oedema, with specific emphasis on the new treatments available for acute swellings.

Hereditary angioedema (HAE) has been recognized for almost 150 years. The newest form of HAE, where C1 inhibitor levels are normal (HAE-nC1INH), was first described in 2000. Over the last two decades, new types of apparent non-mast cell–mediated angioedema with normal quantity and activity of C1INH have been described, in some cases with proven genetic pathogenic variants that co-segregate with angioedema expression within families. Like HAE due to C1INH deficiency, HAE-nC1INH patients are at risk of serious morbidity and mortality. Therefore, proactive management and treatment of HAE-nC1INH patients after an expert physician diagnosis is critically important. The underlying pathophysiology responsible for the angioedema has also been clarified in some of the HAE-nC1INH types. While several clinical guidelines and practice parameters including HAE-nC1INH have been published, we have made substantial progress in our understanding encompassing diagnostic criteria, pathophysiology, and treatment outcomes. HAE International (HAEi) and the US HAE Association (HAEA) convened a symposium of global HAE-nC1INH experts to synthesize our current knowledge in the area. Given the paucity of high-level evidence in HAE-nC1INH, all recommendations are based on expert opinion. This review and expert opinion on the best practice approach to diagnosing and treating HAE-nC1INH will support physicians to better manage patients with HAE-nC1INH.

Angioedema is a prevailing symptom in different diseases, frequently occurring in the presence of urticaria. Recurrent angioedema without urticaria (AE) can be hereditary (HAE) and acquired (AAE), and several subtypes can be distinguished, although clinical presentation is quite similar in some of them. They present with subcutaneous and mucosal swellings, affecting extremities, face, genitals, bowels, and upper airways. AE is commonly misdiagnosed due to restricted access and availability of appropriate laboratorial tests. HAE with C1 inhibitor defect is associated with quantitative and/or functional deficiency. Although bradykinin-mediated disease results mainly from disturbance in the kallikrein–kinin system, traditionally complement evaluation has been used for diagnosis. Diagnosis is established by nephelometry, turbidimetry, or radial immunodiffusion for quantitative measurement of C1 inhibitor, and chromogenic assay or ELISA has been used for functional C1-INH analysis. Wrong handling of the samples can lead to misdiagnosis and, consequently, mistaken inappropriate approaches. Dried blood spot (DBS) tests have been used for decades in newborn screening for certain metabolic diseases, and there has been growing interest in their use for other congenital conditions. Recently, DBS is now proposed as an efficient tool to diagnose HAE with C1 inhibitor deficiency, and its use would improve the access to outbound areas and family members. Regarding HAE with normal C1 inhibitor, complement assays’ results are normal and the genetic sequencing of target genes, such as exon 9 of F12 and PLG , is the only available method. New methods to measure cleaved high-molecular-weight kininogen and activated plasma kallikrein have emerged as potential biochemical tests to identify bradykinin-mediated angioedema. Validated biomarkers of kallikrein–kinin system activation could be helpful in differentiating mechanisms of angioedema. Our aim is to focus on the capability to differentiate histaminergic AE from bradykinin-mediated AE. In addition, we will describe the challenges developing specific tests like direct bradykinin measurements. The need for quality tests to improve the diagnosis is well represented by the variability of results in functional assays.

Hereditary angioedema (HAE) is a rare, potentially life-threatening disorder characterised by recurrent episodes of localised oedema caused by bradykinin overproduction. Accurate epidemiological data are essential for optimising diagnosis and treatment, particularly in underrepresented regions such as the Baltic states. This study aimed to examine the prevalence, clinical characteristics, genetic variants, and treatment accessibility for patients with HAE in the Baltic states of Estonia, Latvia, and Lithuania. This retrospective study included HAE patients diagnosed according to the WAO/EAACI 2021 criteria between 2004 and 2024. Demographic, clinical, and genetic data were collected and evaluated. Descriptive statistical analysis was performed using Jamovi (version 2.3). A total of 78 patients were identified in Estonia (n=30), Latvia (n=12) and Lithuania (n=36) from 2004 till 2024. In Lithuania, 7 patients had died and 3 were lost to follow-up, resulting in 26 patients remaining under active observation. While the total number of HAE cases identified across the three countries was reported, detailed clinical data and analyses were limited to the 68 patients who were alive and actively followed at the time of data collection. Estonia exhibited the highest point prevalence (2.19 per 100, 000), while Latvia had the lowest (0.65). The median diagnostic delay was longest in Latvia (24 years) and shortest in Estonia (9.5 years). gene pathogenic variants predominated. Estonia had the broadest availability of treatments, whereas Latvia had restricted access to modern therapies. Considerable variation exists in HAE prevalence, diagnosis, and treatment across the Baltic states. Estonia exemplifies best practices, while Latvia remains underserved. Regional collaboration and standardised care protocols are urgently needed.