STOP-HAE: A Phase 3 Study of ADX-324 in HAE

Key Inclusion Criteria: * Age ≥18 years at the time of signing informed consent. * Have a documented diagnosis of HAE-1/HAE-2 (Type I or II) * Experience ≥1 Investigator-confirmed HAE attack in the first 4 weeks of Screening or ≥2 Investigator-confirmed HAE attacks in 8 weeks of Screening. * Have access to, and the ability to use, at least one acute HAE therapy to treat HAE attacks (eg, plasma-derived or recombinant C1-INH concentrate or a BK2-receptor antagonist) that has previously been shown to be effective for the participant. * Participants must be deemed medically appropriate for on-demand treatment as the sole medicinal management for their HAE during the study, per Investigator. * Women of childbearing potential must have a negative serum pregnancy test during Screening and a negative urine pregnancy test on Study Day 1 before study drug administration and must agree to use acceptable contraceptive methods if engaged in sexual activity of childbearing potential (refer to Section 13.2.2) from the time of signing the informed consent form (ICF) until the EOS Visit or 1 month after study drug administration, whichever is longer. Key Exclusion Criteria: * Concurrent diagnosis of another form of recurrent angioedema. Examples include, but are not limited to, acquired angioedema, HAE with normal C1-INH (previously known as HAE Type III), idiopathic angioedema, and recurrent angioedema associated with urticaria. * Any clinically significant medical history including, but not limited to, uncontrolled hypertension (defined as systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥ 100 mmHg despite therapy), uncontrolled diabetes mellitus (HbA1c \>9.0%), or current cardiovascular disease, including recent acute coronary syndrome (within the past 6 months), congestive heart failure (NYHA Class III or IV), and significant arrhythmias. * Any clinically significant renal disease * Any clinically significant hepatic disease * Exposure to any of the following LTP for HAE: 1. Chronic prophylaxis with C1-INH (CINRYZE, HAEGARDA, RUCONEST) within 2 weeks prior to Screening. 2. Chronic prophylaxis with berotralstat (ORLADEYO) within 3 weeks prior to Screening. 3. Chronic prophylaxis with lanadelumab (TAKHZYRO) within 8 weeks prior to the Screening. 4. Androgen use within 12 weeks prior to Screening. * Received prior treatment with any RNA/DNA-based therapy for HAE (including ADX-324) or is intolerant of any prior RNA/DNA-based therapy for any condition, excluding vaccines.