BCX7353

The angioedema event rate and the treatment comparisons between each berotralstat dose and placebo in the rate of expert-confirmed angioedema events during the entire dosing period was analyzed using a negative binomial regression model. The number of expert-confirmed angioedema events was included as the dependent variable, the treatment was included as a fixed effect, the stratification variable (baseline monthly angioedema event rate) and study (for the combined study analysis) were included as covariates, and the logarithm of duration on treatment was included as an offset variable. The estimated rate of angioedema events for each treatment group, the treatment differences expressed as the angioedema event rate ratio (berotralstat) over placebo rate ratio), and their associated 95% confidence intervals (CIs) were provided from the negative binomial regression model.

The safety data was assessed for the safety population for subjects who entered Part 2, and includes TEAEs that occurred in Part 1 and Part 2 for these subjects with a data cut-off date of 10-April-2020. TEAEs are defined as AEs that occurred on or after first dose of study treatment, whether in Part 1 or 2, and were assigned to the relevant treatment depending on when the TEAE began (Part 1 or Part 2 treatment). TEAEs were assessed for severity (graded) using the Division of Microbiology and Infectious Disease (DMID) criteria for grading AEs. TEAEs not covered by the DMID criteria were assessed as Mild (Grade 1), Moderate (Grade 2), Severe (Grade 3) or Life-threatening (Grade 4).

The safety data was assessed for the safety population for subjects who entered Part 3, and includes TEAEs that occurred in Part 3 for these subjects.

Treatment comparisons between each berotralstat dose and placebo in the rate of investigator-confirmed HAE attacks during the Part 1 dosing period were analyzed using a negative binomial model. The number of investigator-confirmed attacks was included as the dependent variable, the treatment was included as a fixed effect, the stratification variable (baseline attack rate) was included as a covariate, and the logarithm of duration on treatment was included as an offset variable. The estimated attack rate for each treatment group, the treatment differences expressed as the attack rate ratio (berotralstat over placebo rate ratio), and the associated 95% confidence intervals (CIs) were provided from the negative binomial model.

The safety data was assessed for the safety population, for subjects who entered Part 2 and Part 3, and includes TEAEs that began in Part 2 or 3, respectively, for these subjects. Safety data for Part 2 and Part 3 is combined to clearly show TEAEs occurring in subjects as the proceeded through the 2 study parts. TEAEs are defined as AEs that occurred on or after first dose of study treatment, whether in Part 1 or 2, and were assigned to the relevant treatment depending on when the TEAE began (Part 2 or Part 3 treatment). No statistical analysis was performed on this safety data.

The number and percentage of subjects with treatment-emergent adverse events.

Subjects completed a 3-component VAS on a 100 mm scale for severity of abdominal pain, skin pain and skin swelling associated with the HAE attack, where zero indicated no pain or swelling and 100 mm indicated worst possible pain or swelling. Subjects completed the VAS immediately prior to study drug administration, then at 1, 2, 3, 4, approximately 8 \& at 24 hours post-dose. The primary endpoint was the proportion of subject attacks with an improved or stable 3-symptom composite VAS score at 4 hours post dose. The 3-symptom composite was calculated as the average of the VAS scores for abdominal pain, skin pain, and skin swelling. A subject was considered improved or stable if the change from baseline (CFB; time of drug administration) in VAS was ≤ 0.

The proportion of attacks for which subjects took SOC-Rx in the 24 hours following treatment with study drug. HAE Rescue Medications included C1-INH (Berinert, Cinryze, Ruconest) and Firazyr/Icatibant.

Efficacy was evaluated by the number of acute angioedema attacks. To ensure that consistent, objective assessments were used in accepting subject-reported attack data, a panel of expert physicians in the treatment of HAE patients adjudicated all subject-reported attacks prior to their inclusion in primary efficacy analyses.

Assessment of the proportion of subjects who had no HAE attacks during the entire dosing period