D3.327 - Use of C1 Inhibitor Subcutaneously in the United Kingdom
Background
Hereditary angioedema (HAE) is a rare genetic disorder characterised by recurrent episodes of angioedema, most commonly due to C1-inhibitor deficiency. Long-term prophylaxis (LTP) options include plasma-derived and recombinant C1 inhibitor concentrate (C1-INH), berotralstat, lanadelumab, attenuated androgens, and tranexamic acid. Studies have demonstrated that subcutaneous (SC) C1-INH is a safe and effective option for LTP. However, in the UK, the licensed SC C1-INH preparations are not routinely reimbursed, and usage is very limited. This study aims to evaluate the use and efficacy of SC C1-INH in the UK.
Method
A survey was distributed to all immunology centres in the UK to identify patients who are receiving or have received C1-INH subcutaneously. The survey evaluated reasons for starting SC C1-INH, previous LTP used prior to starting SC C1-INH, AECT scores, product and dosage used, symptom severity before and after use of SC C1-INH, side effects and reasons for discontinuation, if any.
Results
A total of seventeen patients with type 1 HAE in the UK have been on plasma-derived C1-INH subcutaneously, with ages ranging from 8 to 66. Fourteen patients (82%) have trialled an alternative form of LTP prior to starting C1-INH subcutaneously. Reasons for starting SC C1-INH include difficult intravenous access, poor response, side effects to other LTP agents or pregnancy. C1-INH dosages varied from 19 units/kg every two weeks to 50 units/kg twice weekly (median 30 units/kg twice weekly, mean 28 units/kg twice weekly). Fourteen patients (82%) reported an improvement in symptom frequency on SC-C1INH. Six patients (35%) had discontinued or changed treatment. Reasons include needle phobia, pain, inadequate control of symptoms, availability of alternative LTP options and lack of supply.
Conclusion
C1-INH given subcutaneously can be an effective, well-tolerated option for managing HAE, even when used at doses significantly below those reported in clinical trials and should be considered as an option for LTP.
