In this clinical trial, participants with chronic migraine will receive injections with Xeomin or Placebo into muscles of the head and neck. The purpose is to measure the change in monthly migraine days with Xeomin injections compared to Placebo injections.

Trial details include:

• Trial duration: 52 to 55 weeks;

  • Screening period: 4 to 5 weeks;
  • Treatment duration: 4 treatments, each about 12 weeks apart; and

• Visit frequency: about every 4 weeks, 14 visits in total. The first and last visit and the 4 treatment visits are on-site, the other 8 visits are remote by phone / video call.

Inclusion Criteria:

• Participant has a diagnosis of CM with or without aura according to the International Classification of Headache Disorders Edition 3 criteria for ≥ 12 months and is able to distinguish migraine headaches from all other types of headaches;
• Participant age < 50 years at the time of migraine onset;
• Participant meeting the following headache and migraine day criteria in each of the 3 months prior to screening: history of ≥ 15 headache days per month and history of ≥ 8 migraine days per month; and
• During the last 28 days of the screening period, participant experiencing: ≥ 15 headache days and ≥ 8 migraine days that qualify as such per the headache diary.

Exclusion Criteria:

• Diagnosis of other primary headache types, except tension-type headache, which is permitted;
• Diagnosis of aura without headache, migraine with brainstem aura, hemicrania continua, hypnic headache, hemiplegic migraine, retinal migraine, persistent aura without infarction, migraine aura-triggered seizure, or previous migrainous infarction;
• Diagnosis of secondary headache types, except medication overuse headache, which is permitted;
• Currently taking > 1 prescribed drug for the preventive treatment of migraine;
• Discontinuation of anti-calcitonin gene-related peptide (CGRP) / anti-CGRP receptor monoclonal antibody treatment less than 5 months prior to screening.