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.
the mean number of investigator-confirmed hereditary angioedema attacks per month was significantly lower in the garadacimab group than in the placebo group
direct randomised comparison with a large effect and consistent baseline-adjusted sensitivity analysis
the majority (62%) were attack-free during the entire 6 months of treatment compared with no patients who received placebo
large observed difference, tempered by the small cohort and excluded short-exposure placebo participant
FXIIa inhibition was not associated with an increased risk of bleeding or thromboembolic events
no events occurred, but 39 exposed participants over six months cannot resolve rare-event risk
Derived from the full evaluation — not a separate score.
Strengths
The primary analysis found 0.27 investigator-confirmed attacks per month with garadacimab versus 2.01 with placebo, an 87% difference in means with p<0.0001. A baseline-adjusted count-model sensitivity analysis produced a similar 89% difference.
↳ Results and Table 2, pp.1083–85
Allocation was centrally managed through IRT, stratified by age and baseline attack rate, and concealed from sites and relevant funder representatives. Indistinguishable, volume-matched syringes supported masking.
↳ Randomisation and Masking, p.1082
The study tested monthly self- or caregiver-administered prophylaxis in a pivotal phase 3 trial conducted under a US Biological License Application. The intervention targets a defined specialist-managed population with guideline-recognised treatment goals.
↳ Study Design and Participants, p.1081; Procedures, p.1082; Discussion, p.1088
Limitations
The Methods defines efficacy analysis as intention-to-treat, but Table 2 and Figure 2 exclude one placebo participant with fewer than 30 treatment days. Three additional placebo participants discontinued because of attacks, and no attrition-specific sensitivity analysis is reported.
↳ Statistical Analysis, p.1084; Table 2; Figure 1; Results, p.1085
The funder contributed to design, collection, analysis, interpretation, writing, and submission, while sponsor-employed authors participated in formal analysis and data verification. The relationship between those roles and the stated independent third-party analysis is not fully explained.
↳ Methods, p.1081; Role of the Funding Source, p.1085; Contributors, p.1088
The safety population comprised 64 participants followed for six months, including only six adolescents, and 86% were White. These features constrain inference about rare harms and transferability across age and ancestry groups.
↳ Table 1, p.1082; Results, p.1085; Discussion, p.1088
The concealed, double-blind randomised design and prespecified hierarchical analysis support the large reduction in attack rates reported in Table 2. Methodological Rigour is held below the highest band because the stated intention-to-treat definition does not align cleanly with exclusion of one short-exposure placebo participant, and three placebo participants discontinued because of attacks. The contribution remains substantial as pivotal confirmation of a first-in-class mechanism, while placebo control and six-month follow-up leave comparative effectiveness and rare harms unresolved. Multinational recruitment strengthens the application pathway, but the 64-person, predominantly White cohort limits transferability.
Nabu’s assessment, alongside the field’s view.
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Strong4.1
Confidence highThe trial confirms a large prophylactic effect for a first-in-class FXIIa inhibitor in a pivotal phase 3 setting, meaningfully extending the preceding phase 2 evidence. Its contribution remains confirmatory and does not establish comparative superiority over active prophylactic treatments.
“Our phase 3 study was done to confirm the efficacy and safety of once-monthly 200 mg garadacimab.”
Central allocation, double masking, hierarchical testing, a baseline-adjusted sensitivity analysis, and systematic harms collection support the trial's execution. The intention-to-treat description conflicts with the protocol-specified exclusion of one short-exposure placebo participant, while three placebo participants discontinued because of attacks.
“One patient in the placebo group stayed less than 30 days… and was excluded from the analysis.”
The report presents the primary estimate, confidence interval, hierarchy, secondary outcomes, and safety results in a readily traceable sequence. The bleeding and thromboembolic wording is stronger than the small six-month safety sample can establish, although the Discussion calls for continued monitoring.
“bleeding and thromboembolic events will be further closely monitored in the open-label extension study.”
The paper relates garadacimab to guidelines, established prophylactics, the prior phase 2 study, and a caveated comparison with lanadelumab. Small sample size, short follow-up, and inadequate racial and ethnic representation are acknowledged, but demographic implications receive limited analysis.
“The limitations of this trial are the small sample size… the relatively short treatment period… and inadequate racial and ethnic representation.”
Lower confidence on Methodological Rigour — domain match limited.
Caveats4 of 4 checks
The principal results reconcile across the abstract, figures, and tables, but the stated intention-to-treat definition is not fully consistent with the exclusion of one placebo participant from efficacy analyses. The relationship between independent third-party analysis and sponsor participation in analysis is also not fully explained.
Ethics approval, consent, prospective registration, conflicts of interest, and a data-request process are disclosed. Sponsor involvement extended from study design through analysis, interpretation, writing, and submission, making analytical independence a disclosed conduct consideration.
Flags: 4 declared / 5 total
19 of 19 checkable references verified
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No retraction or expression of concern found in Crossref (includes Retraction Watch).
Erratum published 15 Apr 2023 · listed in Crossref
Sources: Crossref (incl. Retraction Watch) ✓
Where this paper’s evidence sits on the path from initial observation to real-world use.
A pivotal multicentre phase 3 trial conducted under a US Biological License Application places the intervention near clinical deployment. Regulatory completion and longer-term safety evidence remain necessary.
“This study was done under a US Food and Drug Administration Biological License Application.”
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