['migraine']
['placebo', 'erenumab', 'erenumab']

        Inclusion Criteria to be assessed prior to entering the subject into the initial screening
        and/or baseline phase:

          -  Provided informed consent prior to initiation of any study-specific
             activities/procedures

          -  History of migraine (with or without aura) for ≥ 12 months prior to screening
             according to the International Headache Society (IHS) Classification The International
             Classification of Headache Disorders (ICHD)-3 (Headache Classification Committee of
             the IHS, 2013),

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

          -  Headache frequency: < 15 headache days per month on average across the 3 months prior
             to screening.

        Inclusion Criteria to be assessed during the baseline phase and confirmed prior to
        randomizing the subject into the double-blind treatment phase:

          -  Demonstrated at least 80% compliance with the electronic Diary (eDiary),

          -  Migraine frequency: ≥ 4 and < 15 migraine days during the baseline phase based on the
             eDiary calculations,

          -  Headache frequency: < 15 headache days during the baseline phase based on the eDiary
             calculations.

        Inclusion Criteria for the Clinical Home Use (CHU) Substudy:

        - Subjects must have provided informed consent for the substudy. Subjects enrolling in the
        CHU substudy must have received open-label 140 mg erenumab for at least 1 dose.

        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 of the following 7 medication categories for
             prophylactic treatment of migraine after an adequate therapeutic trial: Category 1:
             Divalproex sodium, sodium valproate, Category 2: Topiramate, Category 3: Beta blockers
             (for example: atenolol, bisoprolol, metoprolol, nadolol, nebivolol, pindolol,
             propranolol, timolol), Category 4: Tricyclic antidepressants (for example:
             amitriptyline, nortriptyline, protriptyline),Category 5: Serotonin-norepinephrine
             reuptake inhibitors (for example: venlafaxine, desvenlafaxine, duloxetine,
             milnacipran), Category 6: Flunarizine, verapamil, lomerizine, Category 7: Lisinopril,
             candesartan,

          -  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 in the head and/or neck region within 4 months prior to the
             start of the baseline phase or during the baseline phase,

          -  Taken the following for any indication in any month during the 2 months prior to the
             start of the baseline phase: Ergotamines or triptans on ≥ 10 days per month, or Simple
             analgesics (nonsteroidal anti-inflammatory drugs [NSAIDs], acetaminophen) on ≥ 15 days
             per month, or Opioid- or butalbital-containing analgesics on ≥ 4 days per month,

          -  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 (such as schizophrenia and bipolar disorder), or
             current evidence of depression based on a Beck Depression Inventory (BDI)-II total
             score > 19 at screening. Subjects with anxiety disorder and/or major depressive
             disorder are permitted in the study if they are considered by the investigator to be
             stable and are taking no more than 1 medication for each disorder. Subjects must have
             been on a stable dose within the 3 months prior to the start of the baseline phase,

          -  History of seizure disorder or other significant neurological conditions other than
             migraine. Note: A single childhood febrile seizure is not exclusionary,

          -  Malignancy within the 5 years prior to screening, except non melanoma skin cancers,
             cervical or breast ductal carcinoma in situ,

          -  Human immunodeficiency virus (HIV) infection by history,

          -  Hepatic disease by history, or total bilirubin (TBL) ≥ 2.0 x upper limit of normal
             (ULN) or alanine transaminase (ALT) or aspartate aminotransferase (AST) ≥ 3.0 x ULN,
             as assessed by the central laboratory at initial screening, or evidence of acute or
             chronic hepatitis B or hepatitis C virus. Hepatitis status will be evaluated by
             testing for hepatitis B surface antigen (HepBsAg), total hepatitis B core antibody
             (HepBcAb) and hepatitis C antibody by the central laboratory at initial screening.
             Polymerase chain reaction (PCR) should be performed to confirm active disease only if
             total HepBcAb is positive and HepBsAg is negative or if C antibody is positive,

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

          -  History or evidence of any other unstable or clinically significant medical condition
             that, in the opinion of the investigator, would pose a risk to subject safety or
             interfere with the study evaluation, procedures or completion,

          -  Subject has any clinically significant vital sign, laboratory, or electrocardiogram
             (ECG) abnormality during screening that, in the opinion of the investigator, could
             pose a risk to subject safety or interfere with the study evaluation,

          -  The subject is at risk of self-harm or harm to others as evidenced by past suicidal
             behavior or endorsing items 4 or 5 on the Columbia-Suicide Severity Rating Scale
             (C-SSRS) assessed at screening,

          -  Evidence of drug or alcohol abuse or dependence within 12 months prior to screening,
             based on medical records, patient self-report, or positive urine drug test performed
             during screening (with the exception of prescribed medications such as opioids or
             barbiturates),

          -  Pregnant or breastfeeding, or is a female expecting to conceive during the study,
             including through 16 weeks after the last dose of investigational product,

          -  Female subject of childbearing potential who is unwilling to use an acceptable method
             of effective contraception during treatment with investigational product through 16
             weeks after the last dose of investigational product,

          -  Currently receiving treatment in another investigational device or drug study, or less
             than 90 days prior to screening since ending treatment on another investigational
             device or drug study(-ies),

          -  Known sensitivity to any component of the investigational product (Refer to the
             Investigational Product Instruction Manual [IPIM] for details),

          -  Previously randomized into an erenumab study,

          -  Member of investigational site staff or relative of the investigator,

          -  Unlikely to be able to complete all protocol-required study visits or procedures,
             and/or to comply with all required study procedures (eg, independent completion of
             eDiary items) to the best of the subject's and investigator's knowledge.

        Exclusion Criteria for the CHU Substudy:

        - Unreliability as a study participant based on the investigator's (or designee's)
        knowledge of the subject (eg, unwillingness to adhere to the protocol, unwilling to
        self-inject using an autoinjector (AI)/pen after review of the Instructions for Use).
        Subjects receiving erenumab 70 mg in the open-label phase are not eligible.
      