Efficacy Of Lanadelumab In Hereditary Angioedema Patients Switching From C1 Inhibitor Long-Term Prophylaxis: Interim Results From The Help Open-Label Extension Study

Lanadelumab demonstrated sustained prevention of hereditary angioedema (HAE) attacks in the double-blind, phase 3 HELP Study (N=125; NCT02586805). The HELP open-label extension (OLE; NCT02741596) enrolled lanadelumab-treated patients (HELP Study rollover; n=109/113 [96.5%] completers) and lanadelumab-untreated patients (nonrollover; n=103). Here we report interim results (26May2016–1September2017) for rollover and nonrollover patients switching from C1 inhibitor (C1-INH) long-term prophylaxis (LTP) to lanadelumab treatment. All patients ≥12 years old with HAE type I/II received lanadelumab 300 mg every 2 weeks (q2wks); nonrollover switching patients could receive both C1-INH and lanadelumab to Day 15 (LTP tapering period). The number of investigator-confirmed HAE attacks was reported as monthly attack rates (attacks/4 weeks) and compared with historical rates per 4 weeks for the 3 months preceding HELP (rollover)/OLE (nonrollover) treatment. Overall, 106/212 patients (50.0%) received prior C1-INH only LTP (53 rollover and 53 nonrollover). Historical median (range) attack rate for all patients using C1-INH was 2.0 (0.0–15.4)/4 weeks. After lanadelumab treatment median (range) attack rate was 0.1 (0.0–4.1)/4 weeks, representing 97.4% median reduction (74.8% mean reduction). Patients without prior LTP use (n=87) had median (range) attack rates/4 weeks of 1.8 (0.0–27.6) historically and 0.0 (0.0–4.9) with lanadelumab (100% median reduction; 90.2% mean reduction). Patients switching from other LTP (n=19) also experienced attack rate reductions with lanadelumab. Open-label treatment with lanadelumab 300 mg q2wks led to significant reductions in HAE attack rate compared with 3-month historical experience in patients with and without prior C1-INH LTP use, consistent with findings from the HELP Study.