Evaluate long-term efficacy and safety of erenumab in patients with episodic migraine who completed a 5-year open-label treatment phase (OLTP; NCT01952574).

Erenumab demonstrated significant reduction in migraine frequency in short-term studies; however, long-term data are not available.

Following a 12-week placebo-controlled, double-blind treatment period (DBTP), 383 patients continued in the OLTP, receiving erenumab 70mg every 4 weeks, and increasing to 140mg after a protocol amendment (after ~2 years in OLTP). A separate protocol amendment was implemented to resume efficacy data collection in years 4–5. 215 patients completed the 5-year OLTP; 137 had efficacy data at week 268 (end of 5-year OLTP) and were included in this analysis.

Mean (SD) change in monthly migraine days (MMD) from DBTP baseline of 8.5(2.5) days was –4.8(3.9) at week 64 (mean of last 4 weeks of 1-year OLTP; N=129), and –5.3(3.9) at week 268 (mean of last 4 weeks of 5-year OLTP). The percentage of patients achieving MMD response at week 64/268 was 62%/69% for achievement of ≥50% reduction; 41%/48% for ≥75% reduction; and 26%/36% for 100% reduction. Among acute migraine-specific medication (AMSM) users at baseline (6.1[2.7] treatment days/month), mean(SD) change in AMSM days was –3.2(3.5) at week 64 and –4.4(3.3) at week 268. Clinically meaningful improvements were observed in HIT-6^TM: 68%/72% of patients achieved ≥5-point reduction from baseline at weeks 64/268. Exposure-adjusted patient incidence of AEs and serious AEs during OLTP were 92.3 and 2.6 per 100 subject-years, respectively; this was lower than that observed for placebo during DBTP. One fatality (“death unattended”) occurred during safety follow-up period when no erenumab was administered and was considered unrelated to study drug by the investigator.

Patients receiving erenumab through 5 years of treatment demonstrated consistent and sustained response. Safety was comparable to that observed in the full population during the randomized phase of the trial.