COACT Study: CGRPmAbs + OnabotulinumtoxinA Assessment of Chronic Migraine Treatments Study

Inclusion Criteria: * Chronic migraine patients between 18 to 75 years old * Chronic migraine patients with ≥ 12-month history of migraine * Participant has received at least 2 consecutive OnabotulinumtoxinA treatment at screening (visit 1) * Achieved a clinically appropriate response from monotherapy OnabotulinumtoxinA at enrollment (visit 2): * ≥50% reduction in mean monthly headache days of at least moderate severity OR Reduction of ≥7 mean monthly headache days of at least moderate severity OR * HIT-6 reduction of ≥5 points * History of ≥8 monthly migraine days (average from 3 previous months prior to enrollment (visit 2)) Exclusion Criteria: * History of \<8 monthly migraine days (average from 3 previous months prior to enrollment (visit 2)) * Patients with current use, or use within 3 months prior to screening (visit 1) a CGRPmAbs (Aimovig, Ajovy, Emgality, or Vyepti) * Concomitant use of gepants as a preventative treatment \< 1 week prior to screening (visit 1). * Utilizing gepants as an acute rescue treatment \>5 days per month. * Current user of recreational or illicit drugs, or a history within 1 year prior to screening (visit 1) of drug or alcohol abuse or dependence * Clinically significant hematologic, endocrine, cardiovascular, pulmonary, gastrointestinal, or neurologic disease. If there is a history of such a disease, but the condition has been stable for more than 1 year prior to screening (visit 1) and is judged by the PI as not likely to interfere with participation in the study, the participant may be included. * Female is pregnant, planning to become pregnant during the course of the study, or currently lactating.