A Safety and Efficacy Study of Intravenous (IV) Elezanumab Assessing Change in Neurologic Function in Adult Participants With Acute Ischemic Stroke

Inclusion Criteria: * Clinical diagnosis of acute ischemic stroke, supported by acute brain computed tomography (CT) or magnetic resonance imaging (MRI) consistent with the clinical diagnosis. * Able to randomize within 24 hours of last known normal. * National Institute of Health Stroke Scale (NIHSS) total score of 7 to 21, inclusive. * Participants or their legally authorized representative confirms that prior to index stroke, no significant impairment in participant's ability to perform activities of daily living without assistance. Exclusion Criteria: * Evidence of severe stroke on imaging based on available acute imaging studies performed under the standard of care. * Evidence of acute seizure at the onset of index stroke without conclusive imaging of ischemic stroke. * Evidence of acute myocardial infarction. * Symptoms are considered likely to resolve within the subsequent few hours (e.g., transient ischemic attack \[TIA\]). * Known history prior to randomization of clinically significant medical conditions (other than current acute ischemic stroke) or any other reason, including any physical, psychological, or psychiatric condition that in the investigator's opinion would compromise the safety or interfere with the participant's participation in this study. * Known medical history of repeated episodes of complex migraine. Participants with history of complex migraine, but with imaging conclusively demonstrating an acute ischemic stroke are still allowed. * Female who is pregnant, breastfeeding, or considering becoming pregnant during the study or for within 39 weeks (5 half-lives) after the last dose of study drug. * Known receipt of any investigational product within 30 days or 5 half-lives of the drug (whichever is longer) prior to the first dose of study drug. No current enrollment in another interventional clinical study, including pharmacologic and behavioral interventional studies.