Lanadelumab is a human monoclonal antibody against plasma kallikrein indicated for prevention of attacks of hereditary angioedema (HAE). HAE is caused by SERPING1 gene mutations resulting in decreased or dysfunctional plasma protease C1 inhibitor (C1-INH) leading to a loss of inhibition of plasma kallikrein activity with subsequent cleavage of high-molecular weight kininogen and release of bradykinin. There is a clear need for a non-plasma-derived, safe, effective and convenient prophylaxis of HAE attacks to reduce patients' daily burden of disease and disability. The percentage of patients who were attack-free for the last 16 weeks of a controlled study was 77% in the group receiving 300 mg lanadelumab every 2 weeks, compared with 3% with placebo. The most common side effects were mild injection-site reactions. Lanadelumab has the potential to change the approach from on-demand treatment to prophylaxis in HAE. Future studies will have to confirm long-term safety and efficacy of prophylactic long-term inhibition of plasma kallikrein.