KVD900-303 is an open-label, multicenter clinical trial in patients aged 2 to 11 years old with HAE Type I or II.

Inclusion Criteria:

1. Male or female patients 2 to 11 years of age.
2. Confirmed diagnosis of HAE Type I or II.
3. For patients ≥20 kg at screening, patient has had at least 1 documented HAE attack in the last year prior to screening.
4. Caregiver, as assessed by the Investigator, must be able to appropriately store and administer IMP and be able to read, understand, and complete the diary.
5. Investigator believes that the patient and caregiver are willing and able to adhere to all protocol requirements.
6. Parent or Legally Authorized Representative (LAR) provides signed informed consent and patient provides assent (when applicable).

Exclusion Criteria:

1. Any concomitant diagnosis of another form of chronic angioedema, such as acquired C1 inhibitor deficiency, HAE with normal C1-INH, idiopathic angioedema, or angioedema associated with urticaria.
2. A clinically significant history of poor response to bradykinin receptor 2 blocker, C1-INH therapy, or plasma kallikrein inhibitor therapy for the management of HAE, in the opinion of the Investigator.
3. Patient weighs <9.5 kg.
4. Use of angiotensin-converting enzyme inhibitors after the Screening Visit.
5. Any estrogen-containing medications with systemic absorption (such as oral contraceptives including ethinylestradiol or hormonal replacement therapy) within 7 days prior to the Screening Visit.
6. Patients who require sustained use of strong cytochrome P450 3A4 (CYP3A4) inhibitors or inducers or moderate CYP3A4 inducers.
7. Any clinically significant comorbidity or systemic dysfunction, which in the opinion of the Investigator, would jeopardize the safety of the patient by participating in the trial.
8. Known hypersensitivity to sebetralstat or to any of the excipients.
9. Participation in any interventional investigational clinical trial within 4 weeks of the last dosing of investigational drug prior to the Screening Visit.

Data will not be shared until all global regulatory filings are complete.