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BackgroundLanadelumab demonstrated efficacy in preventing hereditary angioedema (HAE) attacks in the phase 3 HELP Study.ObjectiveTo assess time to onset of effect and long-term efficacy of lanadelumab, based on exploratory findings from the HELP Study.MethodsEligible patients with HAE type I/II received lanadelumab 150 mg every 4 weeks (q4wks), 300 mg q4wks, 300 mg q2wks, or placebo. Ad hoc analyses evaluated day 0-69 findings using a Poisson regression model accounting for overdispersion. Least-squares mean monthly HAE attack rate for lanadelumab was compared with placebo. Intrapatient comparisons for days 0-69 versus steady state (days 70-182) used a paired t test for continuous endpoints or Kappa statistics for categorical endpoints.ResultsOne hundred twenty-five patients were randomized and treated. During days 0-69, mean monthly attack rate was significantly lower with lanadelumab (0.41-0.76) vs placebo (2.04), including attacks requiring acute treatment (0.33-0.61 vs 1.66) and moderate/severe attacks (0.31-0.48 vs 1.33, all P ≤ .001). More patients receiving lanadelumab vs placebo were attack free (37.9%-48.1% vs 7.3%) and responders (85.7%-100% vs 26.8%). During steady state, the efficacy of lanadelumab vs placebo was similar or improved vs days 0-69. Intrapatient differences were significant with lanadelumab 300 mg q4wks for select outcomes. Lanadelumab efficacy was durable-HAE attack rate was consistently lower vs placebo, from the first 2 weeks of treatment through study end. Treatment emergent adverse events were comparable during days 0-69 and 70-182.ConclusionProtection with lanadelumab started from the first dose and continued throughout the entire study period.

In 1996, 18 of 20 pertussis outbreaks reported in Massachusetts occurred in schools. Pertussis surveillance data were reviewed and a retrospective cohort study was conducted in a high school that experienced an outbreak. Bordetella pertussis isolates from 9 school cases and from 58 cases statewide were examined by use of pulsed-field gel electrophoresis (PFGE). Statewide incidence rates were highest among children aged <1 year, 10-14 years, and 15-19 years (106, 117, and 104 cases per 100,000, respectively). Among 34 confirmed and 20 probable cases at the school, 61% had cough onset within 8 weeks of school opening. Five different PFGE types were identified among the 58 B. pertussis isolates from throughout the state. All 9 isolates from the affected high school were the same PFGE type. School-aged children may play an important role in pertussis epidemics. Consideration should be given to use of acellular pertussis vaccines among school-aged children. Copyright © 2000 The University of Chicago [ABSTRACT FROM AUTHOR]

Long-term prophylaxis (LTP) has been shown to reduce the frequency of hereditary angioedema (HAE) attacks; however, attacks occurring in patients receiving LTP have not been well characterized. The objective of this systematic review was to evaluate the proportion of type I/II HAE (HAE-C1INH) patients who experience attacks while receiving LTP, the characteristics of these attacks, and associated on-demand therapy use. A systematic search was conducted in PubMed to identify studies reporting LTP use with plasma-derived C1 inhibitor (pdC1INH), lanadelumab, berotralstat, androgens, or antifibrinolytics in patients with HAE-C1INH. Forty-five primary studies met the inclusion criteria. In phase 3 trials, attack-free rates were 40% for subcutaneous pdC1INH 60 IU/kg twice weekly at 16 weeks, and 44% for lanadelumab 300 mg every second week at 6 months (77% during steady-state [days 70-182]); there was no difference in attack-free rate for berotralstat 150 mg versus placebo at 24 weeks. Phase 3 studies reported a lower average attack severity with subcutaneous and intravenous pdC1INH versus placebo. With lanadelumab and berotralstat, the prophylactic treatment effect was more pronounced in peripheral attacks than in abdominal and laryngeal attacks. Laryngeal attacks accounted for 2%-7% of all attacks in observational and interventional studies, regardless of the LTP agent received. On-demand therapy was used in 49%-94% of attacks occurring in the presence of LTP. In conclusion, patients receiving LTP experienced attacks in all anatomic locations, including the larynx. Most attacks were treated with on-demand therapy, although outcomes were not reported. Access to on-demand therapy remains essential for all people with HAE-C1INH., (© 2024. The Author(s).)

Background: Hereditary angioedema (HAE) is a complex disorder with a wide array of treatment options. Shared decision-making (SDM) should be used to ensure that patients are choosing their best treatment option. The goal was to develop and psychometrically test a brief instrument for assessing the patient's perspective of the SDM process during his or her clinical encounters with an HAE specialist/allergist. Method: We hypothesized that SDM could be used effectively to help patients in their choice of therapy for HAE. Ten HAE treating physicians from the United States with a total of 50 patients with HAE used SDM to help patients choose the best prophylactic therapies (oral kallikrein inhibitor, androgens, subcutaneous C1 inhibitor replacement therapy, intravenous C1 inhibitor replacement therapy, monoclonal antibody kallikrein inhibitor) for their HAE and then completed surveys to analyze the effectiveness of the implementation of SDM as a quality indicator in health services assessment. Results: The congruence of answers between the physicians and the patients was then analyzed; 90% of the patient-physician pairs agreed that the advantages and disadvantages of the treatment options were precisely explained; 92% of the patient-physician pairs agreed that the physician helped them understand all the information and that the physician asked them which treatment option they preferred; 88% of the pairs agreed that the different treatment options were thoroughly weighed and 92% of the pairs felt that they selected a treatment option together. Conclusion: In summary, SDM is being implemented by treating physicians to determine the best management options for their patients with HAE.

Background: Hereditary angioedema (HAE) is a rare genetic disorder characterized by painful, debilitating, and potentially fatal swelling attacks. Lanadelumab is approved as long-term prophylaxis (LTP) in patients with HAE. However, real-world data on LTP use in patients with HAE are limited. Objective: To describe clinical characteristics, attack history, and quality of life (QoL) of patients with HAE type I/II who were receiving lanadelumab or other LTPs. Methods: Data were drawn from the Adelphi HAE Disease Specific Program, a cross-sectional survey of HAE physicians conducted in the United States from July to November 2021. Physician-reported disease characteristics, HAE attack frequency, and QoL were compared among patients receiving lanadelumab or other LTPs for at least 12 months. Results: Physicians reported data for 144 patients, of whom 29 had received lanadelumab and 115 had received another prophylaxis for at least 12 months. The mean ± standard deviation number of attacks in the previous 12 months was lower among patients receiving lanadelumab than other LTPs (2.3 ± 3.1 versus 3.4 ± 2.8, respectively; p = 0.075). Although both groups had similar current disease activity and severity, more patients receiving lanadelumab versus other LTPs had high disease activity (51.7% versus 12.5%, respectively; p < 0.0001) and disease severity rated as severe (51.7% versus 16.1%, respectively; p = 0.0001) at diagnosis. Physicians reported that more patients who received lanadelumab had good or very good QoL (72.4%) than those receiving other LTPs (36.5%) (p = 0.003). Conclusion: Analysis of these findings suggests lower attack frequency, lower symptomatic impact, and better QoL in patients treated with lanadelumab than another prophylaxis in a real-world setting.

Background: Lanadelumab was well tolerated and effective in preventing hereditary angioedema (HAE) attacks in the phase 3, double-blind, placebo-controlled Hereditary angioEdema Long-term Prophylaxis (HELP) study and subsequent HELP open-label extension (OLE) study (NCT02741596)., Objective: To evaluate outcomes from HELP OLE for adolescent patients aged 12 to 17 years., Methods: The HELP OLE study comprised patients who completed the HELP study (rollovers) and new eligible (lanadelumab-naive) patients. Rollovers received a single dose of lanadelumab 300 mg at the last HELP study visit (day 0). Treatment was then paused until patients experienced their first investigator-confirmed HAE attack, after which lanadelumab 300 mg was administered every 2 weeks for up to 33 months (4 wk/mo). Lanadelumab-naive patients received lanadelumab 300 mg every 2 weeks from day 0. Patient-reported outcomes included Angioedema Quality of Life Questionnaire. Safety was monitored throughout the study., Results: The subgroup analysis included 21 patients (8 rollovers and 13 lanadelumab-naive patients); 95.2% completed at least 30 months in the study. The mean (SD) monthly attack rate decreased from 1.58 (1.0) at baseline to 0.11 (0.2) during treatment (mean, 94.7% reduction). A total of 8 (38.1%) patients were attack-free during treatment and, on average, 99.1% of days were attack-free (mean, 27.7 d/mo). Patients reported a mean (SD) Angioedema Quality of Life Questionnaire total score of 27.5 (17.5) at baseline vs 7.5 (13.2) at the end of the study. There were 12 (57.1%) patients who reported treatment-related treatment-emergent adverse events; however, there were no treatment-related serious adverse events., Conclusion: Lanadelumab provided long-term efficacy in preventing HAE attacks, was associated with clinically meaningful improvements in health-related quality of life and high levels of treatment satisfaction, and was well tolerated in adolescent patients., Trial Registration: ClinicalTrials.gov Identifier: NCT02741596., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Hereditary angioedema is a rare disorder characterized by episodic, potentially life-threatening swelling caused by kallikrein-kinin dysregulation. Long-term prophylaxis can stabilize this system. Donidalorsen, an antisense oligonucleotide, specifically reduces prekallikrein expression., Methods: In this phase 3, double-blind, randomized trial, we assigned patients with hereditary angioedema to receive donidalorsen (80 mg subcutaneously) or placebo once every 4 or 8 weeks. The primary end point was the time-normalized number of investigator-confirmed hereditary angioedema attacks per 4 weeks (attack rate) from week 1 to week 25., Results: A total of 90 patients received donidalorsen every 4 weeks (45 patients), donidalorsen every 8 weeks (23 patients), or placebo (22 patients). The least-squares mean time-normalized attack rate was 0.44 (95% CI, 0.27 to 0.73) in the 4-week group, 1.02 (95% CI, 0.65 to 1.59) in the 8-week group, and 2.26 (95% CI, 1.66 to 3.09) in the placebo group. The mean attack rate from week 1 to week 25 was 81% lower (95% CI, 65 to 89) in the 4-week group than in the placebo group (P<0.001) and 55% lower (95% CI, 22 to 74) in the 8-week group than in the placebo group (P = 0.004); the median reduction in the attack rate from baseline was 90% in the 4-week group, 83% in the 8-week group, and 16% in the placebo group. The mean attack rate during weeks 5 to 25 was 87% lower (95% CI, 72 to 94) in the 4-week group than in the placebo group (P<0.001) and 60% lower (95% CI, 25 to 79) in the 8-week group than in the placebo group. Donidalorsen administered every 4 weeks resulted in an improvement in the least-squares mean total score for the change at week 25 on the Angioedema Quality-of-Life Questionnaire (scores range from 0 to 100, with a score of 100 indicating the worst possible quality of life) that was 18.6 points (95% CI, 9.5 to 27.7) better than that with placebo (P<0.001). The most common adverse events were erythema at the injection site, headache, and nasopharyngitis; 98% of adverse events were mild or moderate in severity., Conclusions: Donidalorsen treatment reduced the hereditary angioedema attack rate, a finding that supports potential prophylactic use for hereditary angioedema. (Funded by Ionis Pharmaceuticals; OASIS-HAE ClinicalTrials.gov number, NCT05139810.)., (Copyright © 2024 Massachusetts Medical Society.)

Background: Hereditary angioedema (HAE) is a potentially fatal disease characterized by unpredictable, recurrent, often disabling swelling attacks. In a randomized phase 2 study, donidalorsen reduced HAE attack frequency and improved patient quality-of-life (ISIS721744-CS2, NCT04030598). We report the 2-year interim analysis of the phase 2 open-label extension (OLE) study (ISIS 721744-CS3, NCT04307381)., Methods: In the OLE, the on-treatment study period consisted of fixed (weeks 1-13, donidalorsen 80 mg subcutaneously every 4 weeks [Q4W]) and flexible (weeks 17-105, donidalorsen 80 mg Q4W, 80 mg every 8 weeks [Q8W], or 100 mg Q4W) dosing periods. The primary outcome was incidence and severity of treatment-emergent adverse events (TEAEs). The secondary outcomes included efficacy, pharmacodynamic, and quality-of-life assessments., Results: Seventeen patients continued in the OLE study. No serious TEAEs or TEAEs leading to treatment discontinuation were reported. Mean monthly HAE attack rate was 96% lower than the study run-in baseline rate (mean, 0.06/month; 95% confidence interval [CI], 0.02-0.10; median, 0.04 on-treatment vs. mean, 2.70/month; 95% CI, 1.94-3.46; median, 2.29 at baseline). Mean monthly attack rate for Q8W dosing (n = 8) was 0.29 (range, 0.0-1.7; 95% CI, -0.21 to 0.79; median, 0.00). Mean plasma prekallikrein and D-dimer concentrations decreased, and Angioedema Quality of Life Questionnaire total score improved from baseline to week 105 with donidalorsen., Conclusion: The 2-year interim results of this phase 2 OLE study of donidalorsen in patients with HAE demonstrated no new safety signals; donidalorsen was well tolerated. There was durable efficacy with a 96% reduction in HAE attacks., (© 2023 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Background: Berotralstat is a first-line, once-daily oral plasma kallikrein inhibitor approved for prophylaxis of hereditary angioedema (HAE) attacks in patients 12 years or older., Objective: This analysis examined the safety and effectiveness of long-term prophylaxis with berotralstat., Methods: APeX-2 was a phase 3, parallel-group, multicenter trial in patients with HAE caused by C1-inhibitor deficiency (NCT03485911). Part 1 was a randomized, double-blind, placebo-controlled evaluation of 150 and 110 mg of berotralstat over 24 weeks. In part 2, berotralstat-treated patients continued the same treatment, and placebo-treated patients were re-randomized to 150 or 110 mg of berotralstat for 24 weeks. In part 3, all patients were treated with open-label berotralstat at 150 mg, which could be continued for up to an additional 4 years. In part 3, the primary endpoint was long-term safety and tolerability. Secondary endpoints included HAE attack rates and quality of life (QoL)., Results: Eighty-one patients entered part 3. Treatment-emergent adverse events (TEAEs) occurred in 82.7% of patients, with most being mild or moderate in severity. The most common TEAEs were nasopharyngitis, urinary tract infection, abdominal pain, arthralgia, coronavirus infection, and diarrhea. Drug-related TEAEs occurred in 14.8% of patients, but none were serious. For patients who completed 96 weeks of berotralstat treatment (n = 70), the mean (standard error) change in attack rate from baseline was -2.21 (0.20) attacks/mo. Clinically meaningful improvements in QoL were also observed, with the largest improvements in the functioning domain., Conclusion: Berotralstat was generally well tolerated, provided rapid and sustained reductions in HAE attacks and improved QoL over 96 weeks., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: Music is helpful to young people in healthcare contexts, but less is known about the acceptability of music-based interventions for youth living at home with chronic pain who may be struggling to attend school and participate in social activities. The Songs of Love (SOL) foundation is a national nonprofit organization that creates free, personalized, original songs for youth facing health challenges. The aims of this study were (1) to assess acceptability of SOL from the perspective of youth with chronic pain receiving a song and singer-songwriters who created the songs, and (2) to explore the role of music more generally in the lives of young people living with pain., Methods: Twenty-three people participated. Fifteen youth (mean age 16.8) were interviewed and received a song, and six singer-songwriters were interviewed about creating the songs. (Two additional people participated in pilot interviews.) Acceptability was assessed by (1) proportion of youth who participated in a second interview about their song and (2) results of reflexive thematic analysis (RTA) to determine acceptability. Themes addressing the role of music in the lives of youth with pain were also explored using RTA., Results: The program was acceptable as 12 of 15 youth (80 %) participated in second interviews and themes met the definition of acceptability. Three themes addressing the role of music in the lives of youth living with pain were identified., Conclusions: This is the first report of the acceptability and experience of SOL and contributes to research on the benefits of music for pain management., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

Background: Hereditary angioedema (HAE) is characterized by recurrent and unpredictable episodes of subcutaneous and/or submucosal swelling. Objective: To characterize the real-world treatment burden associated with existing on-demand therapies, we analyzed administration-site adverse drug reactions (ADR) associated with approved on-demand HAE therapies reported in the U.S. Food and Drug Administration's (FDA) Adverse Event Reporting System (FAERS). Methods: We searched the FAERS database from October 1, 2009, to March 31, 2022, for reports of all FDA-approved on-demand therapies for HAE: plasma-derived C1-inhibitor (pdC1-INH), ecallantide, icatibant, and recombinant C1-inhibitor (rhC1-INH). ADRs in which the drug was listed as the "primary suspect" were recorded for each drug. ADR preferred terms were grouped into 18 ADR domains based on semantic and/or clinical similarity, and the number of reports for each drug was calculated per year from the time of approval through March 2022, and descriptive results were presented. Preferred terms associated with administration-site ADRs identified from clinical trials and denoted on approved HAE drug U.S. package inserts were examined in a complementary analysis. Results: The highest reported rates of administration-site ADRs per year were site pain (17.9 reports per year), site erythema (7.4 per year), and site swelling (6.7 per year). RhC1-INH was the only drug for which access-site complications and/or malfunctions were reported (9.5 per year). PdC1-INH had the highest rate of incorrect route of product administration (3.7 per year). PdC1-INH showed statistically significant elevated reporting rate of injection-site reactions (reporting odds ratio [ROR] 3.59 [2.36-5.46]; empirical Bayesian geometric mean [EBGM] 1.97 [1.39]). Icatibant and rhC1-INH showed a statistical trend toward an increased reporting rate of administration-site reactions. Conclusion: Real-world data from FAERS were generally consistent with adverse events reported in clinical trials and suggest that patients experience substantial treatment burden associated with FDA-approved parenteral on-demand therapies for HAE attacks. It should be noted that ADR rates are not exposure adjusted and are based on spontaneous reporting.

Background: Hereditary angioedema (HAE) is a rare condition marked by swelling episodes in various body parts, including the extremities, upper airway, face, intestinal tract, and genitals. Long-term prophylaxis (LTP), prescribed to control recurring HAE attacks, is integral to its management. Previously, attenuated androgens (AAs) were the only oral LTP options. However, in 2020, berotralstat, an oral plasma kallikrein inhibitor, was approved in the United States. A 2018 survey of adults with HAE type I or type II showed that almost all the patients who used prophylactic HAE medication preferred oral treatment (98%) and felt that it fit their lifestyle better than injectable treatment (96%). Still, guidelines lack consensus on transitioning patients from AAs to alternative oral prophylactic therapy. Objective: This paper aims to share expert insights and patient feedback on transitioning from AAs to berotralstat, an alternative oral prophylactic therapy, from the perspective of clinicians with extensive experience in treating patients with HAE. Methods: A panel of five HAE specialists convened for a virtual half-day roundtable discussion in April 2023. Results: Discussions about transitioning from AAs to berotralstat were prompted by routine consultations, patient inquiries based on independent research, ineffective current treatment, or worsening AA-related adverse effects. For patients who switched from AAs, the physicians reported that the decision was influenced by the alternative therapy's ability to prevent HAE attacks, its safety, and the once-daily administration schedule. All expert panel members identified fewer AA-related adverse effects; better quality of life; and less severe, shorter, and less frequent HAE attacks as clinical or patient goals they hoped to achieve through the treatment switch. Conclusion: The emergence of new, highly specific LTP drugs for HAE calls for the development of comprehensive recommendations and guidelines for transitioning from AAs to alternative oral prophylactic therapy. The expert panel highlighted key factors to consider during the development of such guidelines.

Background: Real-world data on subcutaneous C1INH (C1INH[SC]) usage and patient-level impacts on hereditary angioedema (HAE)-related outcomes and quality of life (QoL) are both lacking and challenging to generate using conventional study methodologies. Using a hybrid study design involving patient interviews supplemented by retrospective medical chart data review, we conducted a real-world assessment of the impact of C1INH(SC) prophylaxis on HAE attack patterns, QoL, and on-demand medication use., Methods: The study was conducted at seven US sites and included 36 adults with HAE who had been treated with C1INH(SC) long-term prophylaxis following ≥ 12 months of on-demand management only. Patients underwent 30-min interviews, facilitated and analyzed by a trained qualitative research specialist. Medical records were reviewed for 12 months before (pre-index) and after (post-index) initiation of C1INH(SC). Using interview data with descriptive terms converted to numerical values, we compared pre- versus post-index attack frequency, severity, and rescue medication usage., Results: Mean (SD) annualized attack frequency per patient decreased 82.0%, from 38.8 (38.8) attacks/year pre-index to 7.0 (15.3) attacks/year (P < 0.001); the median number of attacks decreased by 97.0% (30 pre-index to 1 post-index). For 20 patients, the annualized attack rate after starting C1INH(SC) prophylaxis was ≤ 1 attack/year; 12 of these patients reported 0 attacks. Mean (SD) attack severity (scale: 0 = none/mild to 4 = very severe) decreased from 2.3 (0.7) pre-index to 0.9 (0.9) post-index (P < 0.001). Mean/median rescue medication use decreased by 77.2%/96.3%. Improved QoL was narratively described for many domains., Conclusions: These real-world findings indicate that long-term prophylaxis with C1INH(SC) markedly improves important factors that contribute to the goal of achieving total disease control and normalization of patients' lives, including fewer and less severe attacks, less rescue medication usage, and improved QoL., (© 2023. The Author(s).)

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

Background: Hereditary angioedema is a rare and potentially life-threatening genetic disease that is associated with kallikrein-kinin system dysregulation. Garadacimab (CSL312), a novel, fully-human monoclonal antibody that inhibits activated factor XII (FXIIa), is being studied for the prevention of hereditary angioedema attacks. The aim of this study was to evaluate the efficacy and safety of once-monthly subcutaneous administrations of garadacimab as prophylaxis for hereditary angioedema., Methods: VANGUARD was a pivotal, multicentre, randomised, double-blind, placebo-controlled, phase 3 trial that recruited patients (aged ≥12 years) with type I or type II hereditary angioedema across seven countries (Canada, Germany, Hungary, Israel, Japan, the Netherlands, and the USA). Eligible patients were randomly assigned (3:2) to receive garadacimab or placebo for 6 months (182 days) by an interactive response technology (IRT) system. Randomisation was stratified by age (≤17 years vs >17 years) and baseline attack rate (1 to <3 attacks per month vs ≥3 attacks per month) for the adult group. The randomisation list and code were kept by the IRT provider during the study, with no access by site staff and funding representatives. All patients and investigational site staff, and representatives from the funder (or their delegates) with direct interaction with the study sites or patients, were masked to treatment assignment in a double-blind fashion. Randomly assigned patients received a 400-mg loading dose of subcutaneous garadacimab as two 200-mg injections or volume-matched placebo on day 1 of the treatment period, followed by five additional self-administered (or caregiver-administered) monthly doses of 200-mg subcutaneous garadacimab or volume-matched placebo. The primary endpoint was the investigator-assessed time-normalised number of hereditary angioedema attacks (number of hereditary angioedema attacks per month) during the 6-month treatment period (day 1 to day 182). Safety was evaluated in patients who received at least one dose of garadacimab or placebo. The study is registered with the EU Clinical Trials Register, 2020-000570-25 and ClinicalTrials.gov, NCT04656418., Findings: Between Jan 27, 2021, and June 7, 2022, we screened 80 patients, 76 of whom were eligible to enter the run-in period of the study. Of 65 eligible patients with type I or type II hereditary angioedema, 39 were randomly assigned to garadacimab and 26 to placebo. One patient was randomly assigned in error and did not enter the treatment period (no dose of study drug received), resulting in 39 patients assigned to garadacimab and 25 patients assigned to placebo being included. 38 (59%) of 64 participants were female and 26 (41%) were male. 55 (86%) of 64 participants were White, six (9%) were Asian (Japanese), one (2%) was Black or African American, one (2%) was Native Hawaiian or Other Pacific Islander, and one (2%) was listed as other. During the 6-month treatment period (day 1 to day 182), the mean number of investigator-confirmed hereditary angioedema attacks per month was significantly lower in the garadacimab group (0·27, 95% CI 0·05 to 0·49) than in the placebo group (2·01, 1·44 to 2·57; p<0·0001), corresponding to a percentage difference in means of -87% (95% CI -96 to -58; p<0·0001). The median number of hereditary angioedema attacks per month was 0 (IQR 0·00-0·31) for garadacimab and 1·35 (1·00-3·20) for placebo. The most common treatment-emergent adverse events were upper-respiratory tract infections, nasopharyngitis, and headaches. FXIIa inhibition was not associated with an increased risk of bleeding or thromboembolic events., Interpretation: Monthly garadacimab administration significantly reduced hereditary angioedema attacks in patients aged 12 years and older compared with placebo and had a favourable safety profile. Our results support the use of garadacimab as a potential prophylactic therapy for the treatment of hereditary angioedema in adolescents and adults., Funding: CSL Behring., Competing Interests: Declaration of interests TJC is a speaker for Pharming, CSL Behring, Takeda, Fresenius Kabi, and Grifols; has received research and consultancy grants from CSL Behring, Takeda, BioCryst, Ionis, Spark, BioMarin, Fresenius Kabi, and Grifols; and is on the medical advisory board for the US Hereditary Angioedema Association, Director of ACARE Angioedema Center at Penn State University, Hershey, and on the Board of Directors for the American Academy of Allergy, Asthma, and Immunology. AR received research grants as a principal investigator, speaker, and advisor for CSL Behring, Takeda-Shire, BioCryst, Pharming, Pharvaris, Ionis, and Shulov Innovative Science. HHL is a speaker for Pharming, CSL Behring, Takeda, and BioCryst and has received research and consultancy grants from CSL Behring, Takeda, BioCryst, Ionis, BioMarin, Pharming, and Phavaris. JSJ is a speaker for Takeda-Shire, CSL Behring, Teva, AstraZeneca, GSK, Sanofi Genzyme, and Regeneron and has received research funding or consultancy fees from CSL Behring, Takeda-Shire, BioCryst, Novartis, Genentech, AstraZeneca, Allakos, Fresenius Kabi, GSK, and Regeneron. JAB is a consultant, principal investigator, and speaker for CSL Behring, Takeda-Shire, Pharming, and BioCryst; is a consultant or principal investigator for KalVista, Biomarin, and Ionis; and is a consultant for Astria, ONO Pharmaceutical, Pharvaris, and Cycle Pharmaceuticals. HFa received research grants from CSL Behring, Takeda, and Pharming; has served as an advisor for CSL Behring, Takeda, Pharming, KalVista, ONO Pharmaceutical, and BioCryst; and has participated in clinical trials or registries for BioCryst, CSL Behring, Pharming, KalVista, Pharvaris, and Takeda. WHY has been a speaker and advisory board member and has received honoraria from CSL Behring, Takeda-Shire, Novartis, Sanofi Genzyme, and Merck; has received research grants from CSL Behring, Takeda-Shire, BioCryst, Pharming, Aimmune, DBV Technologies, Eli Lilly, Pharvaris, AstraZeneca, Novartis, GSK, Genentech-Roche, Amgen, Sanofi Genzyme, Regeneron, Galderma, AnaptysBio, Glenmark, ALK Pharma, Dermira, Ionis, and Celgene; serves as a medical advisor (volunteer) for HAE Canada, a patient organisation; and is a member of Angioedema Centers of Reference and Excellence. ESGS has received lecturing or advertising board fees from Amgen, Sanofi, Novartis, AstraZeneca, Esperion, Ionis-Akcea, and Merck, paid to their institution. IO has received honoraria or served as a consultant or participated in advisory boards for CSL Behring, Takeda-Shire, and Torii Pharmaceutical Company. RTa is a speaker for BioCryst, CSL Behring, Pharming, AstraZeneca, Sanofi-Regeneron, GSK, and Takeda; has served as a consultant for BioCryst, CSL Behring, KalVista, Pharming, and Takeda; and has received grants or research support from BioCryst, CSL Behring, Ionis, KalVista, Pharvaris, and Takeda. MEM is a speaker for CSL Behring, Takeda, Pharming, BioCryst, GSK, Amgen, Sanofi-Regeneron, AstraZeneca, Blueprint, and Genentech; has received research grants from CSL Behring, Takeda, Pharming, BioCryst, KalVista, Pharvaris, GSK, Novartis, Merck, and Allakos; and has been a consultant for CSL Behring, Takeda, Pharming, BioCryst, KalVista, and Cycle Pharmaceuticals. WRL is a speaker for CSL Behring, Pharming, AstraZeneca, Sanofi-Regeneron, GSK, and Takeda-Shire; has served as a consultant for BioCryst, BioMarin, CSL Behring, Fresenius Kabi, Intellia, KalVista, Pharming, Pharvaris, and Takeda-Shire; is a board member of the US Hereditary Angioedema Association Medical Advisory Board; and has received grants or research support from ALK Pharma, BioCryst, CSL Behring, Ionis, Gossamer, KalVista, Kedrion, Therapure, and Takeda-Shire. IMS has received honoraria, research funding, and travel grants from BioCryst, CSL Behring, Pharming, Octapharma, KalVista, and Takeda-Shire and has served as a consultant or participated in advisory boards for these companies. EA-P has received honoraria as a speaker or advisor or grant support or clinical trial investigator support from BioCryst, BioMarin Europe, Centogene, CSL Behring, KalVista, Pharming, Pharvaris, and Takeda-Shire. BR has been a speaker and advisory board member for CSL Behring and Takeda, but has not received personal reimbursement for these activities. BR has participated in multiple clinical trials involving investigational drugs for CSL Behring, Takeda, BioCryst, Dyax, and Pharming, but does not hold patents or investments with these companies or involving this product, and serves as a volunteer Medical Scientific Advisor to HAE Canada, a patient organisation. GLS has been an advisory board member for CSL Behring and has participated in clinical trials for investigational drugs for CSL Behring, Takeda, BioCryst, Dyax, Pharming, Pharvaris, and KalVista. JA is a speaker bureau member for CSL Behring, Pharming, BioCryst, and Takeda and has received consulting fees from; is a clinical trial investigator for BioCryst, CSL Behring, Pharming, Takeda, KalVista, Pharvaris, and BioMarin; and has received consulting fees from Cycle Pharmaceuticals. KK has been a clinical trial investigator for CSL Behring. YS has received speaker fees from Novartis, AstraZeneca, Takeda-Shire, and Torii Pharmaceutical Company and has been a clinical trial investigator for CSL Behring. PS has received honoraria, research funding, travel grants, or has served as a consultant or participated in advisory boards for CSL Behring, Octapharma, Pharming, Shire, and Takeda. RTr has received honoraria, travel grants, or has participated in clinical trials or advisory boards for CSL Behring, Shire, and Takeda. HFe, FG, and IJ are full-time employees and shareholders of CSL Behring. MM has received financial support from CSL Behring for acting as a study centre investigator during the conduct of the study and personal fees from CSL Behring, Takeda-Shire, Pharming, BioCryst, Novartis, Octapharma, and KalVista outside the submitted work., (Copyright © 2023 Elsevier Ltd. All rights reserved.)