A Study of LY2951742 in Participants With Migraine

To assess the efficacy and safety of LY2951742 in the prevention of migraine headache in migraineurs with or without aura during 3 months of treatment.

The study is comprised of 4 trial periods:

1. Screening and washout (5-45 days)
2. Baseline for assessment of the type, frequency, and severity of headaches (28-38 days)
3. Treatment (12 weeks)
4. Follow-up (12 weeks)

Eligibility Criteria:
Inclusion Criteria:

* Have a history of migraine as defined by the International Headache Society (IHS) International Classification of Headache Disorders II guidelines 1.1 and 1.2 (ICHD-II, Cephalgia 2004) of at least 1 year prior to enrollment, migraine onset prior to age 50, and a moderate frequency of migraine headaches
* Women of child-bearing potential (not surgically sterile or at least 1 year post-menopause) must test negative for pregnancy at the time of screening based on a serum pregnancy test and must agree to use a reliable method of birth control during the study and for 3 months following completion of participation in the study
* Have clinical laboratory test results within normal reference ranges or, if outside the normal range, judged not clinically significant by the Investigator
* Must not be on any migraine prevention therapy, including botulinum toxin (Botox)
* Agree not to post any personal medical data related to the study or information related to the study on any website or social media site (for example, Facebook, Twitter, et cetera) until the trial has completed

Exclusion Criteria:

* Current enrollment in, or discontinuation within the last 30 days from, a clinical trial involving any investigational drug or device, or concurrent enrollment in any other type of medical research judged not to be scientifically or medically compatible with this study
* Previous completion or withdrawal from this study or any other study investigating LY2951742 or other therapeutic antibodies that target calcitonin gene-related peptide (CGRP)
* History of chronic migraine or migraine subtypes including hemiplegic (sporadic or familial) migraine, ophthalmoplegic migraine, and basilar-type migraine
* History of headache (for example, cluster headache or Medication Overuse Headache \[MOH\]) other than migraine or tension type headache as defined by IHS ICHD-II within 12 months prior to randomization
* Evidence of significant active psychiatric disease including, but not limited to, manic depressive illness, schizophrenia, generalized anxiety disorder, obsessive compulsive disorder, personality disorders, or other serious mood, anxiety, depression, or substance use disorders
* Have a history or presence of any other medical illness that in the judgment of the Investigator, indicates a medical problem that would preclude study participation
* Women who are pregnant or nursing
* Confirmed corrected QT (QTc) interval \>470 milliseconds (msec) for women and \>450 for men
* Excessive alcohol, opiate, or barbiturate use; history of drug abuse or dependence
* In the opinion of the Investigator, have no other issues that would interfere with compliance with the study requirements and completion of evaluations required for this study