Riedl MA, et al. - In this Phase 3, multicenter, randomized, double-blind, placebo-controlled, parallel-group study (OPuS-2), avoralstat was tested for its efficacy and safety as a prophylactic for patients with hereditary angioedema due to deficiency of C1 inhibitor (C1-INH-HAE). They compared the angioedema attack rate based on adjudicator-confirmed attacks among patients who were administered avoralstat 300 mg, avoralstat 500 mg, or placebo orally 3 times per day for 12 weeks. Based on the findings, avoralstat was not proved to be efficacious as a prophylactic for angioedema attacks in C1-INH-HAE. However, shortened angioedema episodes and improved QoL were seen in the avoralstat 500 mg treatment group vs placebo.