['acute ischemic stroke']
['natalizumab', 'placebo']

        Key Inclusion Criteria:

          -  Clinical diagnosis of supratentorial acute ischemic stroke defined by LKN ≤24 hours
             prior to study treatment initiation.

          -  Score of 5 to 23 points, inclusive, on the NIHSS at Screening for subjects initiating
             treatment ≤9 hours from LKN. Note: NIHSS eligibility must be confirmed within 60
             minutes prior to randomization.

          -  Score of 5 to 15 points, inclusive, on the NIHSS at Screening for subjects initiating
             treatment >9 to ≤24 hours from LKN. Note: NIHSS eligibility must be confirmed within
             60 minutes prior to randomization.

          -  Prior to index stroke, patient was able to perform basic activities of daily living
             without assistance: dressing, eating, walking, bathing, and using the toilet.

          -  For those subjects who underwent a cranial MRI, there is at least 1 acute infarct with
             a diameter of ≥2 cm on baseline brain diffusion-weighted imaging.

        Key Exclusion Criteria:

          -  Lacunar or isolated brainstem or cerebellar stroke based on clinical assessment and
             available acute imaging studies performed under the standard of care.

          -  Presence of acute intracranial hemorrhage on acute brain CT or MRI. However, petechial
             hemorrhages of ≤1 cm are not exclusionary.

          -  Severe stroke defined by imaging criteria based on either one of the following:

          -  Alberta Stroke Program Early CT (ASPECT) score of 0 to 4 based on head CT or

          -  Acute infarct volume on MRI diffusion weighed imaging greater than or equal to 70 mL

          -  Seizure at the onset of stroke.

          -  Known history of prior treatment with natalizumab.

          -  Known history of active viral hepatitis B or C.

          -  Signs and symptoms of active or acute infection.

        NOTE: Other protocol-defined inclusion/exclusion criteria may apply.
      