Randomized, double-blind, placebo-controlled, parallel-group, multicenter study followed by an open-label treatment phase (OLTP). To evaluate the effect of erenumab (AMG 334) compared to placebo on the change from baseline in monthly migraine days.

This is a Phase 2, randomized, double-blind, placebo-controlled study in participants with episodic migraine. The study's double blind treatment phase (DBTP) is designed to evaluate if treatment with erenumab once a month for 6 months compared with placebo is effective in reducing the mean monthly migraine days. Additionally, this study will continue to evaluate the efficacy and safety of erenumab during the OLTP where participants will continue to receive active treatment monthly.

The study also includes a clinical home use (CHU) sub-study to assess a participant's ability to self-administer 140 mg of erenumab. Participants will be randomized 1:1 to use either 2 pre-filled 70 mg/mL autoinjector (AI)/pens or 1 pre-filled 140 mg/mL AI/pen. Participation in the substudy is optional, and no additional samples will be collected for the sub-study.

After implementation of Protocol Amendment 2, the dose of erenumab in the OLTP increased from 70 mg to 140 mg QM. Participants who had already completed week 48 remain on 70 mg QM, participants not yet starting the OLTP, or not yet completing the week 48 visit receive erenumab 140 mg QM for the remainder of the OLTP.

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.

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request

Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication (or other new use) have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors, and if not approved, may be further arbitrated by a Data Sharing Independent Review Panel. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the link below.