This study evaluates the efficacy of eptinezumab to prevent migraine in participants with chronic migraine.

This is an interventional, multi-regional, multi-site, randomized, double-blind, placebo-controlled Phase III study, to confirm the efficacy and safety of eptinezumab in participants with chronic migraine who are eligible for preventive treatment.

participants will be randomly allocated to one of three treatment groups: eptinezumab 300 mg, eptinezumab 100 mg, or placebo.

The double-blind, placebo-controlled treatment period will be followed by an extension period where all participants will receive active treatment to further assess the safety and tolerability of eptinezumab.

The total study duration from the Screening Visit to the Safety Follow-up Visit is approximately 36 weeks and includes a Screening Period (28-30 days), a Placebo-controlled Period (12 weeks), an Extension Period (12 weeks), and a Safety Follow-up Period (8 weeks).

Inclusion Criteria:

• The participant has a diagnosis of CM as defined by IHS ICHD-3 guidelines confirmed at screening visit with a history of migraine onset at least 12 months prior to the Screening Visit.
• The participant has a migraine onset at ≤50 years of age.
• The participant has ≥8 migraine days per month for each month within the past 3 months prior to the Screening Visit.
• The participant fulfils the following criteria for migraine in prospectively collected information in the eDiary during the screening period:
• Migraine occurring on ≥8 days and headache occurring on ≥15 to ≤26 days.
• The participant has demonstrated compliance with the Headache eDiary by entry of data for at least 24 of the 28 days following the Screening Visit.
• The participant is aged ≥18 (≥20 for Taiwan) and ≤75 years at the Screening Visit.

Exclusion Criteria:

• The participant has received any medication targeting the calcitonin gene-related peptide (CGRP) pathway as preventive treatment of migraine.
• The participant has confounding and clinically significant pain syndromes, (for example, fibromyalgia, chronic low back pain, complex regional pain syndrome).
• The participant has a diagnosis of acute or active temporomandibular disorder.
• The participant has a history or diagnosis of chronic tension-type headache, hypnic headache, cluster headache, hemicrania continua, new daily persistent headache, or unusual migraine subtypes such as hemiplegic migraine (sporadic and familial), ophthalmoplegic migraine, migraine with brainstem aura and migraine with neurological accompaniments that are not typical of migraine aura (diplopia, altered consciousness, or long duration).
• The participant has a lifetime history of psychosis, bipolar mania, or dementia.
• Participants with other psychiatric conditions whose symptoms are not controlled or who have not been adequately treated for a minimum of 6 months prior to screening are also excluded.
• The participant has a history of clinically significant cardiovascular disease, including uncontrolled hypertension, vascular ischaemia or thromboembolic events (for example, cerebrovascular accident, deep vein thrombosis, or pulmonary embolism).

Other inclusion and exclusion criteria may apply