A Study to Evaluate the Efficacy and Safety of Erenumab (AMG 334) in Chronic Migraine Prevention

This study consisted of the following phases: screening, 4-week baseline phase, 12-week
double-blind treatment, and 12-week follow-up. Participants may have elected to participate
in the optional pharmacokinetic substudy and the optional, novel patient-reported outcome
(PRO) assessment substudy.

Participants who completed the 12-week double-blind treatment phase of Study 20120295 were
eligible to enroll in an open-label extension study (Study 20130255; NCT02174861).

Inclusion Criteria:

- History of at least 5 attacks of migraine without aura and/or migraine with visual
sensory, speech and/or language, retinal or brainstem aura.

- History of ≥ 15 headache days per month of which ≥ 8 headache days were assessed by
the subject as migraine day.

- ≥ 4 distinct headache episodes, each lasting ≥ 4 hours OR if shorter, associated with
use of a triptan or ergot-derivative on the same calendar day based on the eDiary
calculations.

- Demonstrated at least 80% compliance with the eDiary.

Exclusion Criteria:

- History of cluster headache or hemiplegic migraine headache

- Unable to differentiate migraine from other headaches

- Failed > 3 medication categories due to lack of efficacy for prophylactic treatment of
migraine .

- Received botulinum toxinin head or neck region within 4 months prior to screening.

- Used a prohibited migraine prophylactic medication, device or procedure within 2
months prior to the start of the baseline phase