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

Adults with a history of migraine with or without aura for ≥ 12 months and who experience ≥ 4
to < 15 migraine days per month with < 15 headache days per month will be randomized 1:1 to
placebo or erenumab. Double-blind erenumab or placebo will be administered during the 12-week
double-blind treatment phase and open-label erenumab will be administered during the 28-week
open-label treatment phase.

Inclusion Criteria:

- History of migraines (with or without aura) for ≥ 12 months

- Migraine frequency: ≥ 4 and < 15 migraine days per month on average acrossthe 3 months
prior to screening

- Headache (ie, migraine and non-migraine headache) frequency: < 15 headache days per
month on average across the 3 months prior to screening

- Demonstrated compliance with the eDiary

Exclusion Criteria:

- Older than 50 years of age at migraine onset.

- History of cluster headache or hemiplegic migraine headache.

- Unable to differentiate migraine from other headaches

- No therapeutic response with > 2 categories for prophylactic treatment of migraine
after an adequate therapeutic trial.

- Concomitant use of 2 or more medications with possible migraine prophylactic effects
within 2 months prior to the start of the baseline phase or during the baseline phase.
If only 1 prophylactic medication is used, the dose must be stable within 2 months
prior to the start of the baseline phase and throughout the study

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

- Received botulinum toxin

- Anticipated to require any excluded medication, device, or procedure during the study.

- Active chronic pain syndromes (such as fibromyalgia and chronic pelvic pain).

- History of major psychiatric disorder.

- History of seizure disorder or other significant neurological conditions other than
migraine.

- Human immunodeficiency virus (HIV) infection by history.

- Myocardial infarction (MI), stroke, transient ischemic attack (TIA), unstable angina,
or coronary artery bypass surgery or other revascularization procedure within 12
months prior to screening.

- The subject is at risk of self-harm or harm to others. Previously randomized into an
AMG 334 study.

- Unlikely to be able to complete all protocol required study visits or procedures,
and/or to comply with all required study procedures.