Study of Oral Deucrictibant XR Tablet for Prophylaxis and Deucrictibant IR Capsule for On-Demand Treatment of Angioedema Attacks in Adults With Acquired Angioedema Due to C1 Inhibitor Deficiency

The study consists of a Screening Period, during which eligibility is confirmed, a Part 1 Prophylaxis Double-blind Treatment Phase, a Part 2 On-demand, Double-blind Treatment Phase, and a Part 3 On-demand Open-label Extension Phase. Approximately 24 participants will be randomized in Part 1 into 2 parallel arms for a treatment period of 12 weeks. During the prophylaxis treatment period participants will receive blinded study drug (deucrictibant 40 mg XR or placebo randomized in a 1:1 ratio). Upon completion of Part 1, participants will roll-over into Part 2. In addition to rollover participants completing Part 1, new deucrictibant treatment-naïve participants will be enrolled directly into Part 2 and this may occur while Part 1 is ongoing. During the on-demand period participants will receive blinded study drug (deucrictibant 20 mg IR capsule or matching placebo randomized in a 1:1 ratio, 2-period, 2-treatment crossover design) for 2 qualifying AAE-C1INH attacks. Participants completing Part 2 may roll over into Part 3 where all AAE-C1INH attacks will be treated with open-label deucrictibant 20 mg soft capsule.