Efficacy and Safety Study of BCX7353 as an Oral Treatment for the Prevention of Attacks in HAE

Key Inclusion Criteria:

- A clinical diagnosis of hereditary angioedema Type 1 or Type 2, defined as having a
C1-INH functional level and a C4 level below the lower limit of the normal (LLN)
reference range, as assessed during the Screening period.

- Subject weight of ≥ 40 kg

- Access to and ability to use one or more acute medications approved by the relevant
competent authority for the treatment of acute attacks of HAE

- Subjects must be medically appropriate for on-demand treatment as the sole medicinal
management for their HAE during the study.

- Subjects must have a specified number of investigator-confirmed attacks during the
run-in period of a maximum of 56 days from the Screening visit.

- Acceptable effective contraception

- Written informed consent

Key Exclusion Criteria:

- Pregnancy or breast-feeding

- Any clinically significant medical condition or medical history that, in the opinion
of the Investigator or Sponsor, would interfere with the subject's safety or ability
to participate in the study

- Any laboratory parameter abnormality that, in the opinion of the Investigator, is
clinically significant and relevant for this study

- Severe hypersensitivity to multiple medicinal products or severe hypersensitivity/
anaphylaxis with unclear etiology

- Use of C1-INH within 14 days or use of androgens or tranexamic acid within 28 days
prior to the Screening visit for prophylaxis of HAE attacks, or initiation of these
drugs during the study

- Current participation in any other investigational drug study or received another
investigational drug within 30 days of the Screening visit

- Prior enrollment in a BCX7353 study