The research was presented at the 2018 American Academy of Allergy Asthma & Immunology (AAAAI)/World Allergy Organization (WAO) Joint Congress, which took place in Orlando, Florida.
Patients with HAE have reduced levels or a dysfunction of either C1-INH protein, or coagulation factor XII. While factor XII is involved in blood clotting, C1-INH controls inflammation.
If lacking (in HAE type 1) or functioning abnormally (type 2), patients experience episodes of swelling due to the excessive production of a pro-inflammatory protein fragment called bradykinin.
The use of engineered, or recombinant, human forms of C1-INH (rhC1-INH) is a common approach in the treatment of acute hereditary angioedema attacks, which aims to increase the amount of C1-INH in the blood. Ruconest, marketed by Pharming Group, is an approved medication using this strategy.
Despite a known effectiveness, information on whether the time to ease HAE symptoms varies across different body locations was lacking.
Aiming to address this gap, the researchers used data from two double-blind trials with open-label extensions, which refers to study periods with no use of placebo. Patients ages 12 and older with acute hereditary angioedema attacks were randomly assigned to either rhC1-INH 50 U/kg or a placebo.
The start of symptom relief at an attack location was assessed with the visual analog scale (VAS), which has been used to evaluate severity of acute attacks in hereditary angioedema.
The results showed that treatment with rhC1-INH shortened the mean time to symptom relief in all HAE attack locations compared to placebo, including abdominal (60 vs. 240 minutes), peripheral — which may affect the hands, arms, legs, feet, or genitals (105 vs. 303 minutes) — oro-facial-pharyngeal-laryngeal, which spans the mouth, face, jaw, pharynx, and larynx (64.5 vs. 306 minutes), and urogenital attacks (119 vs. 320 minutes).
Time to start relief of facial attacks was 158 minutes with rhC1-INH. The researchers were unable to determine the corresponding result in the group receiving placebo.
“Treatment with rhC1INH 50 U/kg was efficacious in shortening time to symptom relief of acute HAE attacks, regardless of attack location,” the scientists wrote.