Background <p>The EMPOWER Study (NCT03845400) was a phase 4, observational, non-interventional, multicenter study evaluating the real-world effectiveness and safety of lanadelumab in patients with hereditary angioedema (HAE). This subanalysis focused on lanadelumab effectiveness and safety in patients from Canada.</p> Methods <p>Enrollment included patients with HAE due to C1 inhibitor deficiency. Patients were categorized as “newly treated” or “established on lanadelumab” if they had received fewer than four or at least four doses before enrollment, respectively.</p> Results <p>Thirteen patients from Canada were enrolled: seven newly treated and six established on lanadelumab; these patients received lanadelumab for a mean (standard deviation [SD]) duration of 315 (224) and 536 (366) days, respectively, during the study. In newly treated patients, the mean (SD) observed HAE attack rate decreased after lanadelumab initiation from 1.5 (2.9) to 0.3 (0.6) attacks per month. In patients established on lanadelumab, the mean (SD) observed HAE attack rate was 0.1 (0.1) attacks per month throughout the study. Most HAE attacks were mild or moderate in severity (newly treated, 94%; established on lanadelumab, 100%). No study discontinuations were attributed to treatment-emergent adverse events. All treatment-emergent adverse events were non-severe, non-serious, and unrelated to lanadelumab treatment.</p> Conclusions <p>Lanadelumab lowered the HAE attack rate among newly treated Canadian patients and maintained a low attack rate among those previously established on lanadelumab, demonstrating robust effectiveness across both patient groups. Effectiveness, tolerability, and safety of lanadelumab were consistent with the overall population from the EMPOWER Study, supporting the use of lanadelumab as a first-line long-term prophylactic treatment for patients with HAE in Canada.</p> Trial registration <p>NCT03845400, registered February 19, 2019.</p>