APeX-A, 7353-312, is a single-arm, open-label, multicenter study. The study will be conducted in countries where berotralstat is not available either commercially or via another mechanism. All enrolled subjects will receive the planned marketed dose of berotralstat, 150 mg QD. The study will assess the long term safety and tolerability of berotralstat. Eligible subjects will be enrolled directly into Study BCX7353-312 (Study 312) from Studies 302 and 204. Subjects will receive berotralstat 150 mg administered orally once daily (QD). Subjects will return to the clinic every 24 weeks for drug dispensation and safety monitoring for up to 240 weeks (approximately 5 years). Safety and tolerability will be evaluated through assessment of serious adverse events (SAEs) and treatment-related, treatment-emergent adverse events (TEAEs). Up to 110 subjects are planned to enroll.

OBJECTIVE: The purpose of this article is to review the available trials that led to the Food and Drug Administration (FDA) approval of berotralstat, an oral kallikrein inhibitor, for the prevention of hereditary angioedema (HAE) attacks. DATA SOURCES: PubMed and ClincalTrials.gov were searched using key term berotralstat to identify phase III clinical trials related to the FDA approval of berotralstat from April 2018 to May 2021. STUDY SELECTION AND DATA EXTRACTION: Trials selected were those that influenced the FDA approval of berotralstat or provided novel information regarding the safety and efficacy of this therapy in the treatment of HAE. DATA SYNTHESIS: Both APeX-2 and ApeX-J found clinically significant benefit with berotralstat 150 mg daily for reduction in HAE attacks when compared with placebo (1.31 vs 2.35, P < 0.001, and 1.11 vs 2.18, P < 0.001, attacks in the APeX-2 and APeX-J trials, respectively). APeX-2 also showed a statistically significant benefit for berotralstat 110 mg daily (1.65 vs 2.35 attacks [1.65 attacks, P = 0.024]). RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE: An advantage berotralstat has over the other approved therapies is that it is administered orally, which may garner patient preference because of ease of administration. Berotralstat has also shown a potential benefit in reducing the need for standard-of-care treatment for HAE attacks, which has not been studied with alternative agents. CONCLUSIONS: Berotralstat 150 mg daily has been proven safe and effective in clinical studies and appears to be a viable oral alternative to parenteral medications currently used in HAE prophylaxis.

Physicians may request access to berotralstat for eligible participants with unmet medical need Physicians can send email inquiries to access.us@inceptua.com or call 1-888-225-8677 Patients who may be interested should contact their physician about participation Berotralstat (BCX7353) will be available through this expanded access program until it is commercially available

This is a single-arm, open-label study designed to evaluate the PK and safety of berotralstat weight-based treatment for the prevention of hereditary angioedema attacks in pediatric participants 2 to \< 12 years of age. This study will consist of two treatment periods: a 12-week standard-of-care (SOC) treatment period followed by an open-label berotralstat treatment period lasting up to 144 weeks. Participants will be enrolled into 4 dose cohorts; participant weight will be used to determine assignment to each cohort with the higher weight cohorts (Cohorts 1 and 2) enrolling first and in parallel. Safety assessments and PK modelling from all available PK data will then be used to confirm the weight bands for sequentially enrolling Cohorts 3 and 4.The effectiveness of berotralstat in this population will be summarized using descriptive statistical methods.

Background: The goal of long‐term HAE prophylaxis is to reduce the number of HAE attacks and the associated disease burden, including treatment with on‐demand medications. Berotralstat is an oral once‐daily selective plasma kallikrein inhibitor that has been shown to reduce HAE attack frequency in the Phase 3 study (NCT03485911). Previous analysis has shown a significant reduction in on‐demand medication use for the overall treated patient population. This analysis evaluated the use of on‐demand medication in patients treated with berotralstat 150mg by relative reduction in HAE attack rate. Method: APeX‐2 was a double‐blind, placebo‐controlled trial in which patients with HAE Type 1 or 2 were randomized to berotralstat 110 mg (N = 41):150 mg (N = 40): placebo (N = 40) daily for 24 weeks in Part 1. For this post hoc analysis, patients were defined as those who had ≥ 50% reduction (Cohort A) or ≥ 70% reduction (Cohort B) in rate of investigator‐confirmed attacks in Part 1 relative to their baseline attack rate. Investigator‐confirmed HAE attacks and on‐demand medication use over 24 weeks were analyzed using a negative binomial model. Results: In Cohort A (n = 23), the mean use of on‐demand medications reduced from 2.7 (±2.14) doses/month at baseline to model‐estimated 0.6 doses/month at week 24. This corresponds to an approximately 78% reduction in on‐demand medication use with 2.1 fewer doses of on‐demand medication per month. In Cohort B (n = 20), the mean use of on‐demand medications reduced from 2.6 (±2.25) at baseline to model‐estimated 0.4 doses/month at week 24. This corresponds to an approximately 85% reduction in on‐demand medication use with 2.2 fewer doses per month. Overall, only 14 of 70 and 12 of 48 of treated HAE attacks in Cohort A and B, respectively, required retreatment with the same or another on‐demand medication during an HAE attack. Retreatment was most common when icatibant was used first‐line. Conclusion: Prophylactic treatment with oral berotralstat 150 mg demonstrated a marked reduction in on‐demand medication use. This effect was amplified in patients who had ≥ 50% reduction or ≥ 70% reduction in rate of investigator‐confirmed attacks. This data, along with the reduction in attack frequency, demonstrates that berotralstat is an effective treatment option that improves HAE disease burden.

BACKGROUND: With no approved treatments in Japan for the prevention of hereditary angioedema (HAE) attacks, there is a significant unmet need for long-term prophylactic therapies for Japanese patients with HAE. Berotralstat (BCX7353) is an oral, once-daily, highly selective inhibitor of plasma kallikrein in development for prophylaxis of angioedema attacks in HAE patients. METHODS: APeX-J is a phase 3, randomized, double-blind, placebo-controlled, parallel-group, 3-part trial conducted in Japan (University Hospital Medical Information Network identifier, UMIN000034869; ClinicalTrials.gov identifier, NCT03873116). Patients with a clinical diagnosis of type 1 or 2 HAE underwent a prospective run-in period of 56 days to determine eligibility, allowing enrollment of those with ≥2 expert-confirmed angioedema attacks. Patients were randomly assigned (1:1:1) and stratified by baseline attack rate (≥2 vs. <2 expert-confirmed attacks/month between screening and randomization) to receive once-daily berotralstat 110 mg, berotralstat 150 mg, or placebo. The primary endpoint was the rate of expert-confirmed angioedema attacks during dosing in the 24-week treatment period. RESULTS: Nineteen patients were randomized to receive once-daily berotralstat 110 mg (n = 6), berotralstat 150 mg (n = 7), or placebo (n = 6). Treatment with berotralstat 150 mg significantly reduced HAE attacks relative to placebo (1.11 vs. 2.18 attacks/month, p = .003). The most frequently reported treatment-emergent adverse events (TEAEs) in berotralstat-treated patients (n = 13) were nasopharyngitis (n = 4, 31%), abdominal pain, cough, diarrhea, and pyrexia (n = 2 each, 15%). CONCLUSIONS: Orally administered, once-daily berotralstat 150 mg significantly reduced the frequency of HAE attacks and was safe and well tolerated, supporting its use as a prophylactic therapy in patients with type 1 or 2 HAE in Japan.

BACKGROUND: Given the recent approval of oral berotralstat in several countries for hereditary angioedema (HAE) prophylaxis, transition from long-term androgens to berotralstat may occur in clinical practice. The open-label, Phase II APeX-S trial provided an opportunity to assess the safety and effectiveness of berotralstat in patients previously treated with differing durations of androgens and shorter transition periods. Therefore, we examined the safety, effectiveness, and impact on quality of life of berotralstat after prior androgen use in patients from the APeX-S trial. Alanine aminotransferase (ALT) elevations were also examined because of the association with androgen exposure and hepatic function impairment. METHODS: We conducted an analysis of a subset of 39 patients from the APeX-S trial aged ≥12 years with HAE due to C1 inhibitor deficiency (HAE-C1-INH) with prior androgen use who discontinued androgen therapy within <60 days of receiving berotralstat. Patients received daily berotralstat (150 mg) and were divided into subgroups for this analysis based on time between androgen discontinuation and berotralstat commencement (<14 days versus 14 to <60 days). RESULTS: Berotralstat was generally well tolerated, with nasopharyngitis (21%), upper respiratory tract infection (15%), nausea (15%), diarrhea (15%), and abdominal pain (10%) being the most common adverse events occurring in ≥10% of the total subset. Only 7/145 (5%) of all APeX-S study patients with a prior history of androgen therapy experienced ALT elevations, 6 of which were grade 3 or 4 toxicities. All 7 patients recovered without sequelae and belonged to the subgroup of patients who transitioned <14 days after discontinuing androgens (n = 18). A reduction in monthly attack rate versus Month 1 was observed over 12 months for all patients who transitioned from prior androgen therapy to berotralstat prophylaxis in under 60 days, irrespective of duration of prior androgen therapy or timing of transition (N = 39). Similarly, meaningful patient-reported improvements from both Angioedema Quality of Life Questionnaire and Treatment Satisfaction Questionnaire for Medication scores were achieved, with a sustained benefit shown over the berotralstat treatment period. CONCLUSIONS: Berotralstat treatment led to sustained HAE symptom control irrespective of duration of prior androgen therapy or timing of transition. Most patients safely transitioned from long-term androgens to berotralstat. Although occurring in a small group of patients, liver-related adverse events following berotralstat treatment may be associated with a shorter androgen washout period, but further research is required to confirm this. CLINICAL TRIAL REGISTRATION: NCT03472040. Retrospectively registered March 21, 2018.

BACKGROUND: Berotralstat is a first-line, once-daily oral plasma kallikrein inhibitor approved for prophylaxis of hereditary angioedema (HAE) attacks in patients ≥12 years. OBJECTIVE: This analysis examined the safety and effectiveness of long-term prophylaxis with berotralstat. METHODS: APeX-2 was a Phase 3, parallel-group, multicenter trial in patients with HAE caused by C1 inhibitor deficiency (NCT03485911). Part 1 was a randomized, double-blind, placebo-controlled evaluation of 150 and 110 mg berotralstat over 24 weeks. In Part 2, berotralstat-treated patients continued the same treatment and placebo-treated patients were re-randomized to 150 or 110 mg berotralstat for 24 weeks. In Part 3, all patients were treated with open-label berotralstat at 150 mg, which could be continued for up to an additional 4 years. In Part 3, the primary endpoint was long-term safety and tolerability. Secondary endpoints included HAE attack rates and quality of life (QoL). RESULTS: Eighty-one patients entered Part 3. Treatment-emergent adverse events (TEAEs) occurred in 82.7% of patients, with most being mild or moderate in severity. The most common TEAEs were nasopharyngitis, urinary tract infection, abdominal pain, arthralgia, coronavirus infection, and diarrhea. Drug-related TEAEs occurred in 14.8% of patients, but none were serious. For patients who completed 96 weeks of berotralstat treatment (n=70), mean (standard error) change in attack rate from baseline was -2.21 (0.20) attacks/month. Clinically meaningful improvements in QoL were also observed, with the largest improvements in the functioning domain. CONCLUSION: Berotralstat was generally well tolerated, provided rapid and sustained reductions in HAE attacks, and improved QoL over 96 weeks.

BACKGROUND: Berotralstat is a once-daily oral inhibitor of plasma kallikrein for the prophylaxis of hereditary angioedema (HAE) in patients ≥12 years. APeX-J aimed to evaluate the efficacy and safety of berotralstat in Japan. METHODS: APeX-J was a Phase III trial comprising 3 parts (NCT03873116). Part 1 was a randomized, placebo-controlled evaluation of berotralstat 150 or 110 mg over 24 weeks. Part 2 was a 28-week dose-blinded phase in which berotralstat-treated patients continued the same dose and placebo patients were re-randomized to berotralstat 150 or 110 mg. In Part 3, all patients remaining on study received berotralstat 150 mg in an open-label manner for up to an additional 52 weeks. The primary endpoint of Parts 2 and 3 was long-term safety and tolerability, and secondary endpoints examined effectiveness. RESULTS: Seventeen patients entered Part 2, and 11 continued into Part 3. Treatment-emergent adverse events (TEAEs) were reported by 14/17 patients (82.4%) in Parts 2 or 3; the most common were nasopharyngitis, abdominal pain, cystitis, influenza, and vertigo. One patient (5.9%) experienced a drug-related TEAE (Grade 4 increased hepatic enzyme). No drug-related serious TEAEs were reported. For patients who completed 26 months of treatment with berotralstat 150 mg (n = 5), mean (standard error of the mean) monthly HAE attack rates and on-demand medication use decreased from baseline by 1.15 (0.09) attacks/month and 2.8 (0.64) doses/month, respectively. Sustained improvements were also observed in patient quality of life and treatment satisfaction. CONCLUSIONS: Long-term prophylaxis with berotralstat raised no new safety signals and was effective at reducing attacks and improving patient-reported outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT03873116. Registered March 13, 2019. Retrospectively registered.

BACKGROUND: Berotralstat (BCX7353) is an oral, once-daily inhibitor of plasma kallikrein in development for the prophylaxis of hereditary angioedema (HAE) attacks. OBJECTIVE: Our aim was to determine the efficacy, safety, and tolerability of berotralstat in patients with HAE over a 24-week treatment period (the phase 3 APeX-2 trial). METHODS: APeX-2 was a double-blind, parallel-group study that randomized patients at 40 sites in 11 countries 1:1:1 to receive once-daily berotralstat in a dose of 110 mg or 150 mg or placebo (Clinicaltrials.gov identifier NCT03485911). Patients aged 12 years or older with HAE due to C1 inhibitor deficiency and at least 2 investigator-confirmed HAE attacks in the first 56 days of a prospective run-in period were eligible. The primary efficacy end point was the rate of investigator-confirmed HAE attacks during the 24-week treatment period. RESULTS: A total of 121 patients were randomized; 120 of them received at least 1 dose of the study drug (n = 41, 40, and 39 in the 110-mg dose of berotralstat, 150-mg of dose berotralstat, and placebo groups, respectively). Berotralstat demonstrated a significant reduction in attack rate at both 110 mg (1.65 attacks per month; P = .024) and 150 mg (1.31 attacks per month; P < .001) relative to placebo (2.35 attacks per month). The most frequent treatment-emergent adverse events that occurred more with berotralstat than with placebo were abdominal pain, vomiting, diarrhea, and back pain. No drug-related serious treatment-emergent adverse events occurred. CONCLUSION: Both the 110-mg and 150-mg doses of berotralstat reduced HAE attack rates compared with placebo and were safe and generally well tolerated. The most favorable benefit-to-risk profile was observed at a dose of 150 mg per day.