Long‐term efficacy and safety of erenumab in migraine prevention: results from a 5‐year, open‐label treatment phase of a randomized clinical trial

Background and purpose Although erenumab has demonstrated significant reduction in migraine frequency and improved quality of life in studies lasting 3 to 12 months, little is known about long-term therapy. Methods This study was an open-label, 5-year treatment phase following a 12-week, double-blind, placebo-controlled trial in adults with episodic migraine. Patients initially received open-label erenumab 70 mg, which increased to 140 mg following a protocol amendment. Efficacy analyses included change from baseline in monthly migraine days (MMDs), monthly acute migraine-specific medication (AMSM) days, and health-related quality of life. Results Of 383 patients enrolled, 250 switched to 140 mg; 215 (56.1%) completed open-label treatment. Mean (standard error) change in MMDs from baseline of 8.7 (0.2) days was -5.3 (0.3) days; an average reduction of 62.3% at year 5. Among patients using AMSM at baseline (6.3 [2.8] treatment days), mean change in monthly AMSM days was -4.4 (0.3) days at the end of 5 years. Patient-reported outcomes indicated stable improvements in disability, headache impact, and migraine-specific quality of life. Exposure-adjusted patient incidence rates of adverse events (AEs) were 123.0/100 patient-years; AEs were most frequently nasopharyngitis, upper respiratory tract infection, and influenza. Serious AEs (SAEs) reported by 49 patients (3.8/100 patient-years) were mostly single occurrence. Two fatal adverse events were reported. There were no increases in incidence of AEs, SAEs, or AEs leading to treatment discontinuation over 5 years of exposure. Conclusions Treatment with erenumab was associated with reductions in migraine frequency and improvements in health-related quality of life that were maintained for at least 5 years. No new safety signals were observed.