Key Inclusion Criteria:  The participant has completed the Primary Outcome Visit (Visit 5) of the lead-in Study 19140A immediately prior to enrolment into this study. The participant is indicated for 60-week preventive treatment of chronic migraine with eptinezumab according to the clinical opinion of the investigator.  Key Exclusion Criteria:  The participant has a serious adverse event (SAE) or a moderate or severe ongoing AE from the Lead-In study considered a potential safety risk by the investigator. The participant has a clinically relevant change in vital signs or electrocardiogram (ECG) from the Lead-In study considered a potential safety risk by the investigator. The participant has a disease or takes medication that could, in the investigator's opinion, interfere with the assessments of safety, tolerability, or efficacy, or interfere with the conduct or interpretation of the study.  Other inclusion and exclusion criteria may apply.