['migraine disorders']
['ald403', 'placebo']

        Inclusion Criteria:

          -  Diagnosis of migraine at ≤ 50 years of age (ICHD-II, 2004 Section 1)

          -  History of migraine ≥ 12 months with

               -  ≤ 14 headache days of which at least 4 have to be migraine days (migraine days
                  count as headache days) in each 28 day period in the 3 months prior to screening

               -  During the 28 days following the screening visit, the subject experiences ≤ 14
                  headache days of which at least 4 have to be migraine days (migraine days count
                  as headache days) as recorded in the eDiary

          -  No use of any botulinum toxin for migraine or for any other medical/cosmetic reasons
             requiring injections in the head, face, or neck 4 months prior to screening and during
             the 28 day period prior to randomization

          -  Headache eDiary was completed on at least 25 of the 28 days prior to randomization

        Exclusion Criteria:

          -  Confounding pain syndromes, e.g. fibromyalgia, complex regional pain syndrome or any
             pain syndrome that requires regular analgesia

          -  Psychiatric conditions that are uncontrolled and untreated, including conditions that
             are not controlled for a minimum of 6 months prior to screening

          -  History or diagnosis of complicated migraine (ICHD- II, 2004 Section 1), chronic
             tension-type headache, hypnic headache, cluster headache, hemicrania continua, new
             daily persistent headache, migraine with brainstem aura, sporadic and familial
             hemiplegic migraine

          -  Unable to differentiate migraine from other headaches

          -  Have any clinically significant concurrent medical condition

          -  Receipt of any monoclonal antibody treatment within 6 months of screening (within or
             outside a clinical trial)

          -  Previously dosed with ALD403 or any monoclonal antibody targeting the CGRP pathway
      