Adverse Event: Any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product that does not necessarily have a causal relationship with this treatment. An adverse event can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product.

A summary of other non-serious AEs, and all SAE's, regardless of causality, is reported in the Adverse Events section.

All randomized participants who received at least one dose of study drug. There were 6 participants in the 120 mg group who discontinued after receiving loading dose of 240mg, these participants were moved to 240mg group for AE analysis.

Pharmacokinetics (PK): Area Under the Concentration Time Curve (AUC) of Galcanezumab

Zero participants analyzed. AUC data was not collected as AUC was not pre-specified in protocol.

Serum Concentrations of Galcanezumab.

All randomized participants with measurable serum concentrations at month 12.

Plasma Concentration of Calcitonin Gene-Related Peptide (CGRP)

All randomized participants with measurable plasma concentration.

A Treatment Emergent Anti-drug Antibody (TE ADA) evaluable participant is considered to be TE ADA+ if the participant has at least one post-baseline titer that is a 4-fold or greater increase in titer from baseline measurement. If baseline result is ADA Not Present, then the participant is TE ADA+ if there is at least one post-baseline result of ADA Present with titer >= 1: 20 (treatment-induced).

There were 6 participants in the 120 mg arm who discontinued after receiving loading dose of 240mg, these participants were moved to 240mg arm for safety analysis.

All randomized participants who received at least one dose of study drug and had baseline and at least one post baseline evaluable data for TE ADA.

MHD: A calendar day on which a migraine headache or probable migraine headache occurred. Overall mean is derived from the average of months 1 to 12 from MMRM model. Least squares mean (LSMean) was calculated using mixed model repeated measures (MMRM) model with treatment, pooled investigative site, month, and treatment by month, baseline, and baseline by month as fixed effects.

All randomized participants who received at least one dose of study drug and had baseline & at least one post baseline value.

Headache Day: A calendar day on which any type of headache occurred (including migraine, probable migraine, and non-migraine headache).

Overall mean is derived from the average of months 1 to 12 from MMRM model. LSMean was calculated using MMRM model with treatment, pooled investigative site, month, and treatment by month, baseline, and baseline by month as fixed effects.

All randomized participants who received at least one dose of study drug and had baseline & at least one post baseline Value.

Migraine Headache Day: A calendar day on which a migraine headache or probable migraine headache occurred.

Overall percentage of participants with a given response rate were estimated from the generalized linear mixed models (GLIMMIX) model.

All randomized participants who received at least one dose of study drug and had baseline & at least one post baseline value.

Overall mean is derived from the average of months 1 to 12 from MMRM model. LSMean was calculated using MMRM model with treatment, pooled investigative site, month, and treatment by month, baseline, and baseline by month as fixed effects.

All randomized participants who received at least one dose of study drug and had baseline and at least one post baseline value.

The Patient Global Impression of Improvement (PGI -I) scale is a participant-rated instrument that measures the participants own global impression of their symptom improvement. The participant was instructed as follows: "Mark the box that best describes your migraine headache condition since you started taking this medicine." Response options were on a 7-point scale in which a score of 1 indicates that the participant's condition is "very much better," a score of 4 indicates that the participant has experienced "no change," and a score of 7 indicates that the participant is "very much worse." Overall mean is derived from the average of months 1 to 12 from MMRM model. LSMean was calculated using MMRM model with treatment, pooled investigative site, month, and treatment by month, baseline PGI-S, and baseline PGI-S by month as fixed effects.

All randomized participants who received at least one dose of study drug and had at least one post baseline value.

The MIDAS is a participant-rated scale which was designed to quantify headache-related disability over a 3-month period. This instrument consists of five items that reflect the number of days reported as missing or with reduced productivity at work or home, and the number of days of missed social events. Each item has a numeric response range from 0 to 90 days, if days are missed from work or home they are not counted as days with reduced productivity at work or home. The numeric responses are summed to produce a total score ranging from 0 to 270, in which a higher value is indicative of more disability. Overall mean is derived from the average of months 1 to 12 from MMRM model. LSMean was calculated using MMRM model with treatment, pooled investigative site, month, and treatment by month, baseline, and baseline by month.

All randomized participants who received at least one dose of study drug and had baseline and at least one post baseline value.

MSQv2.1 is a health status instrument,with a 4-week recall period, developed to address physical & emotional limitations of specific concern to individuals with migraine. Addressing the impact of migraine on work or daily activities, relationships with family & friends, leisure time, productivity, concentration, energy, tiredness & feelings.It consists of 14 items addressing 3 domains:(1)Role Function-Restrictive (items 1-7);(2)Role Function- Preventive (items 8-11);&(3)Emotional Function (items 12-14).Response options range from "none of the time" (value 1) to "all of the time" (value 6), & are reverse-recoded (value 6 to 1) before the domain scores are calculated. Total raw scores for each domain is the sum of the final item value for all of the items in that domain.After total raw score is computed for each domain & total score, they are transformed to a 0-100 scale with higher scores indicating a better health status & a positive change in scores reflecting functional improvement.

All randomized participants who received at least one dose of study drug and had baseline and at least one post baseline value.

Overall mean is derived from the average of months 1 to 12.LSMean was calculated using MMRM model with treatment, pooled investigative site, month, and treatment by month, baseline, and baseline by month as fixed effects.

The PSMQ-M is a self-rated scale which measures participants level of satisfaction with study medication.The scale has been modified for use in this study, assessing 3 items related to the clinical trial treatment over the past 4 weeks: satisfaction, preference, and side effects. Satisfaction responses range from "very unsatisfied" to "very satisfied" with the current treatment. Preference compares the current study medication to previous medications, with responses from "much rather prefer my previous medication" to "much rather prefer the medication administered to me during the study".

All randomized participants who received at least one dose of study drug and had month 12 PSMQ-M measurement.

The SQAAQ is a self-administered questionnaire that provides an assessment of ease of use and confidence with using a device to administer a subcutaneous injection of study drug. Participants will respond to questionnaire items using a 7-point Likert scale (from "Strongly Disagree" to "Strongly Agree") shortly after the injection. If a caregiver administers the injection, the participants should be prepared to provide the caregiver's ratings of the questions.strongly agree & agree are considered as positive responses.

All randomized participants who switched from pre-filled syringe and received at least one dose of study drug by autoinjector.