Despite Prophylactic Treatments, Break-through Attacks Continue among Patients with Hereditary Angioedema

There are several FDA-approved medications for prophylactic treatment of Hereditary Angioedema (HAE). Despite increased use of these therapies, patients continue to experience HAE attacks. We sought to evaluate attack frequency in patients receiving prophylactic treatment. A chart audit study was conducted among physicians treating HAE to collect anonymized information regarding HAE treatments and attacks documented within their patient’s medical record. Physicians were primarily Allergists/Immunologists (n=47) or other specialties (n=28). The study received IRB exemption. A total of 282 patient charts were reviewed, with an average of 3.8 charts per physician. Overall, 83% of patients utilized HAE treatment prophylaxis. The most common medications were lanadelumab-flyo (Takhzyro®, 21%), C1 esterase inhibitor (C1-INH) administered subcutaneously (Haegarda®, 20%), C1-INH administered intravenously (Cinryze®, 18%), and oral androgens (15%). Most patients (n=244, 87%) were also prescribed an on-demand (acute) medication. Among patients prescribed both acute and prophylactic medications for whom on-demand usage was known, 42% used their on-demand medication monthly, for an average of 0.7 times/month. Although the rate of attacks decreased with prophylactic medication use, 30% of patients on prophylaxis experienced one attack in the past month and 52% in the past three months, for an average of 0.5 and 1.2 attacks, respectively. The attack frequency ranged from 0.6-1.7 for Takhzyro® and 0.3-0.9 for Haegarda® during the past one-three months. Physicians (78%) believe patients accurately report their attack frequency. Many patients with HAE on prophylactic medication, including newer subcutaneous therapies, still experience attacks and require on-demand medication treatment. Attack rates should be assessed regularly.