This study used a single-cohort, 2-treatment arms, randomized (1:1 (70 mg:placebo)), double-blind study design in adult subjects with chronic migraine. A screening period of 2 weeks was used to assess initial eligibility, followed by a 4-week baseline period to assess diary compliance and headache frequency.
Eligible patients were then randomized to either erenumab 70 mg or placebo for 12 weeks, followed by an open-label treatment period to last until end of PTA determined by the product launch in the country or the country's decision not to launch. A safety follow-up visit occurred 12 weeks after the last treatment for subjects who discontinue the double-blind treatment or who completed the double-blind treatment period without continuing in the open-label treatment period.
