This is a Phase 3, multicenter, long-term, open-label study to evaluate the safety and efficacy of once-daily orally administered deucrictibant extended-release tablet for prophylaxis to prevent angioedema attacks in participants aged ≥12 years with Hereditary Angioedema

The study consists of a Screening Period during which eligibility is confirmed (only for participants not rolling over within 28 days from a previous deucrictibant prophylactic study), a Treatment Period in which participants will receive open-label deucrictibant extended-release tablet once daily for approximately 130 weeks, followed by an End of Study visit after maximum 4 weeks. Participants will undergo regular safety (e.g. lab draws) and efficacy assessments, will complete an electronic diary daily, and also complete questionnaires at predefined timepoints during the study.

Inclusion Criteria:

1. Provision of the signed ICF by the participant and/or legally designated representative.
2. Male or female, aged ≥12 years at the time of providing written informed consent/assent.
3. Diagnosis of hereditary angioedema (HAE)
4. For participants that did not participate in a previous deucrictibant prophylactic study: history of at least 1 attack in the last 3 consecutive months prior to Screening
5. Reliable access and ability to use standard of care on-demand treatments to effectively manage acute HAE attacks.
6. Willing and able to adhere to all protocol requirements, including eDiary and ePRO data recording.
7. Female participants of childbearing must agree to the protocol specified pregnancy testing and contraception methods.

Exclusion Criteria:

1. Any diagnosis of angioedema other than HAE
2. Participation in a clinical study with any other investigational drug within the last 30 days or within 5 half-lives of the investigational drug at ICF signature (whichever is longer)
3. Prior gene therapy for any indication at any time
4. Participants who discontinued from previous studies with deucrictibant prophylactic and/or on-demand treatment due to safety reasons or compliance issues that, in the opinion of the Investigator, would interfere with the participant's safety or compliance to participate in the study
5. Exposure to ACE inhibitors or any estrogen-containing medications with systemic absorption within 4 weeks of Screening
6. Use of prophylactic treatment for HAE within 2 weeks of Screening for C1INH, oral kallikrein inhibitors, or anti-fibrinolytics; within 4 weeks of Screening for attenuated androgens; within 5 half-lives of Screening for monoclonal antibodies, or within 7 days of Screening for short-term prophylaxis
7. Any females who are pregnant, plan to become pregnant, or are currently breast-feeding
8. Abnormal hepatic function
9. Moderate or severe renal impairment
10. Any clinically significant comorbidity or systemic dysfunction that would interfere with the participant's safety or ability to participate in the study.
11. History of alcohol or drug abuse within the previous year, or current evidence of substance dependence or abuse
12. Use of medications that are moderate and strong inhibitors or strong inducers of CYP3A4 within the last 30 days or within 5 half-lives (whichever is longer) of the time of randomization
13. Known hypersensitivity to deucrictibant or any of the excipients of the study drug