A new study has found that prophylaxis with C1-INH subcutaneously at 60 IU/kg twice per week was effective in preventing attacks of hereditary angioedema (HAE) in Japanese patients.

The study, published in Allergology International, observed a 95% reduction in attacks per month over 16 weeks in Japanese individuals with types I or II HAE.

The study was a prospective, single-arm phase 3 study conducted at 10 centers in Japan between June 2, 2020, and April 28, 2021. Nine participants aged 17 years or older with HAE were included and were administered C1-INH subcutaneously at 60 IU/kg twice weekly for 16 weeks. Data on HAE symptoms, use of rescue medication, and adverse events were collected.

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“There is a need in Japan for a long-term prophylactic treatment for HAE with a well-tolerated safety profile that can be administered to a wide range of patient groups (adolescents, adults, and pregnant and lactating women),” the authors wrote. “This Phase 3 study was conducted to assess the efficacy, pharmacokinetics, and safety of C1–INH in Japanese patients with HAE and to confirm the applicability of the global Phase 3 results to the Japanese population.”

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The primary outcome measures were the time-normalized number of HAE attacks per month and functional activity of C1-INH after the last dose of C1-INH. Secondary endpoints included safety and efficacy, pharmacokinetics and pharmacodynamics, relative reductions in attack rates, and safety and tolerability.

The results were similar to the results of a previous global phase 3 study in which the median number of attacks of HAE was reduced by 95% during the study. The need for rescue medication also declined accordingly, and C1-INH functional activity was restored to near normal.

In addition to reduced attack rates and rescue medication, the researchers observed improvements in all four domains of the angioedema quality of life questionnaire scores among the included patients.


Fukuda T, Yamagami K, Kawahata K. Efficacy, pharmacokinetics, and safety of subcutaneous C1-esterase inhibitor as prophylaxis in Japanese patients with hereditary angioedema: results of a Phase 3 study. Allergol Int. Published online February 28, 2023. doi:10. 1016/j.alit.2023.02.002