The main purpose of this study is to evaulate the efficacy and safety of galcanezumab in participants 6 to 17 years of age for the preventive treatment of episodic migraine. The primary objective is to demonstrate the superiority of galcanezumab versus placebo in the reduction of monthly migraine headache days across the 3-month double-blind treatment period.

The study has two parts which enroll separately from each other such that participants may choose to participate in either but not both: the main study and a study addendum.

• The main study includes a 3-month, randomized, double-blind treatment period in which participants receive either galcanezumab or placebo, followed by a 9-month open-label extension in which all participants receive galcanezumab.
• The study addendum is a stand-alone study of galcanezumab pharmacokinetics and safety in a group of participants separate from those in the main study. The study addendum includes a 5-month evaluation period after a single injection of galcanezumab, followed by a 9-month open-label extension.

Inclusion Criteria:

• Have a diagnosis of migraine with or without aura as defined by the IHS ICHD-3 guidelines (1.1 or 1.2 according to ICHD-3 [2018]), with a history of migraine headaches of at least 6 months prior to screening.

Exclusion Criteria:

• Participants who are taking, or are expected to take, therapeutic antibodies during the course of the study (adalimumab, infliximab, trastuzumab, bevacizumab, etc.). Prior use of therapeutic antibodies is allowed if that use was more than 12 months prior to baseline.
• Known hypersensitivity to monoclonal antibodies or other therapeutic proteins, or to galcanezumab or its excipients.
• Current use or prior exposure to galcanezumab, another CGRP antibody, or CGRP receptor antibody, including those who have previously completed or withdrawn from this study or any other study investigating a CGRP antibody.
• History of IHS ICHD-3 diagnosis of new daily persistent headache, cluster headache or migraine subtypes including hemiplegic (sporadic or familial) migraine and migraine with brainstem aura (previously basilar-type migraine).
• History of significant head or neck injury within 6 months prior to screening; or traumatic head injury at any time that is associated with significant change in the quality or frequency of their headaches, including new onset of migraine following traumatic head injury.
• Participants with a known history of intracranial tumors or developmental malformations including Chiari malformations.

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

Data are available 6 months after the primary publication and approval of the indication studied in the US and EU, whichever is later. Data will be indefinitely available for requesting.

A research proposal must be approved by an independent review panel and researchers must sign a data sharing agreement.