Study to Assess Adverse Events (AEs) When Oral Atogepant Tablet is Given to Adult Chinese Participants Who Completed Study 3101-303-002 to Prevent Chronic Migraine

* Eligible participants completed the double-blind treatment period, and the safety follow-up period, if applicable, depending on the timing of study initiation, of Study 3101-303-002 without significant protocol deviations and who did not experience an adverse event (AE) that, in the investigator's opinion, may indicate an unacceptable safety risk.

* Participants requiring any medication, diet, or nonpharmacological treatment on the list of prohibited concomitant medications or treatments, that cannot be discontinued or switched to an allowable alternative. Concomitant medications with demonstrated efficacy for the prevention of migraine is exclusionary, except that participants from lead-in study 3101-303-002 taking 1 medication with demonstrated efficacy for the prevention of migraine may participate in the current study provided that the dose was stable prior to the lead-in study and the participant is willing to continue taking that medication. * Participants with an electrocardiogram (ECG) indicating clinically significant abnormalities at Visit 1. * Participants with hypertension (sitting systolic blood pressure (BP) \> 160 mm Hg or sitting diastolic BP \> 100 mm Hg) at Visit 1. * Participants with a significant risk of self-harm Columbia-Suicide Severity Rating Scale (C-SSRS), or of harm to others (investigator opinion); participants who report suicidal ideation with intent, with or without a plan, since the last visit, must be excluded. * Participants with clinically significant hematologic, endocrine, cardiovascular, pulmonary, renal, hepatic, gastrointestinal, or neurologic disease.