Purpose of the RAPIDe-3 Study

Potential participants will undergo screening to confirm eligibility for the study.

If eligible, participants will be enrolled in the study to treat two qualifying HAE attacks (one with deucrictibant and one with placebo).

For adolescent participants: Adolescent participants will get one dose of deucrictibant at this visit while in a non-attack state, followed by multiple blood draws over the course of eight hours to check how their body is affected by the active study drug. Adolescent participants will then be enrolled in the study to treat two qualifying HAE attacks (one with deucrictibant and one with placebo).

For all participants: Upon experiencing symptoms of an HAE attack, participants will consult with their study doctor, who will determine if the participant should take the study drug. Participants will answer a series of questionnaires on their handheld device before taking the study drug and at various time points for up to two days after treatment. These will take about 2 to 3 minutes to complete each time.

If the study drug does not provide enough symptom relief during an HAE attack, the participant may contact their study doctor again to discuss how they feel and to find out if they should take a second dose of the study drug. However, if needed, the participant may use their own prescribed HAE medication or study-provided icatibant.

For all participants: Following each HAE attack treated with the study drug, participants will have a study visit to check their health and a one-hour interview will be conducted by telephone or an online communication platform such as Webex. The second follow-up visit will also be the end-of-study visit.