Long-term efficacy and safety of subcutaneous C1-inhibitor in women with hereditary angioedema: subgroup analysis from an open-label extension of a phase 3 trial

BACKGROUND: Women with hereditary angioedema due to C1-inhibitor deficiency (HAE-C1INH) experience more frequent and severe angioedema attacks compared with men. Fluctuations in female sex hormones can influence HAE attack frequency and severity. Subcutaneous C1-INH (C1-INH [SC]) is indicated as routine prophylaxis to prevent HAE attacks. In this post hoc subgroup analysis, we evaluated the efficacy and safety of C1-INH (SC) in female subjects with HAE-C1INH enrolled in an open-label extension of the pivotal phase III COMPACT trial. METHODS: In this multicenter, randomized, parallel-arm trial, eligible subjects (age ≥ 6 years with ≥ 4 attacks over 2 consecutive months) received C1-INH (SC) 40 IU/kg or 60 IU/kg twice weekly for 52 to 140 weeks. Analyses of efficacy endpoints were performed for all female subjects and those of childbearing age (age ≥ 15 to ≤ 45 years), including subjects who became pregnant during the evaluation period. RESULTS: Overall, 91% (69/76) of female subjects were classified as responders (≥ 50% reduction in HAE attacks relative to the pre-study period); 82% experienced < 1 attack/4 weeks. The median number of attacks/month was 0.10, with 96% median reduction in attacks relative to the pre-study period. Results were similar in the subgroup of subjects of childbearing age. Four women who became pregnant during the trial and were exposed to C1-INH (SC) during the first trimester delivered healthy babies with no congenital abnormalities. CONCLUSIONS: C1-INH (SC) prophylaxis was safe and effective in women with HAE-C1INH, including those of childbearing age. Four women exposed to C1-INH (SC) during the first trimester had uneventful pregnancies and delivered healthy babies. Trial registration Clinicaltrials.gov identifier NCT02316353 (Registered December 10, 2014); https://clinicaltrials.gov/ct2/show/NCT02316353.