D2.363 - Lanadelumab Effect on Hereditary Angioedema Activity Score: A Tertiary Center Experience

Hereditary angioedema (HAE) is a rare autosomal dominant condition characterized by recurrent swelling episodes unresponsive to standard allergy treatments. It arises due to C1 inhibitor (C1INH) protein deficiency or dysfunction, caused by mutations in the SERPING1 gene, and is classified into three subtypes based on laboratory findings.

Treatment options include rescue therapy as well as short-term and long-term prophylaxis. Lanadelumab, a plasma kallikrein inhibitor, has been shown to reduce the frequency and severity of attacks and is increasingly used for long-term prophylaxis. Decisions on prophylaxis can be guided by tools like the HAE Activity Score (HAE-AS), a validated measure of disease impact. This study aims to evaluate the impact of lanadelumab on HAE-AS.

We included patients aged ≥16 years with confirmed HAE between November 2023, and December 2024. A total of 19 patients were enrolled. HAE-AS was recorded before therapy initiation and six months after treatment. Lanadelumab was administered at a dose of 300 mg every two weeks during the initial six months. Patients were subsequently weaned to every four weeks if their symptoms were controlled.

Primary outcome was the impact of lanadelumab on HAE-AS. Secondary outcome was whether severe HAE-AS (≥13) at baseline predicted failure to reduce dosing frequency. HAE-AS before and after therapy was compared using a paired t-test, and chi-squared testing was used to assess the association between severe baseline HAE-AS and dosing frequency requirements.

Nineteen patients were included, with a median baseline HAE-AS of 15 (range: 3–23); 15 patients (79%) had severe HAE-AS scores. After six months of treatment, HAE-AS scores significantly improved to a median of 2 (p < 0.001). At follow-up, 67% of patients with severe HAE-AS and 75% of those with non-severe HAE-AS remained controlled after switching to four-week dosing. No significant association was found between severe baseline HAE-AS and the need for higher dosing frequency (p = 0.627).

Our study shows that lanadelumab succesfully decreases the HAE-AS and that a higher score at baseline has no correlation with inability to wean Lanadelumab administration frequency. Further studies with larger cohorts is needed.