Efficacy of SUN N4057 in Subjects With Acute Ischemic Stroke and Measurable Penumbra on Magnetic Resonance Imaging (MRI)

Inclusion Criteria: General inclusion criteria: * Males or females \>= 18 and \<= 85 years of age at randomization. Female subjects must be either: * Surgically sterile; * Postmenopausal for at least 1 year; or * Non-pregnant, confirmed by a serum pregnancy test, and using a method of birth control that is acceptable to the investigator. * Neurological examination demonstrating localizing cortical signs * Receipt of study drug less than 6 hours (50% of subjects) or between 6 and 9 hours, inclusive, (50% of subjects) after the onset of symptoms (for un-witnessed stroke, last time seen in normal state or at bedtime for un-witnessed stroke during sleep) * Signed informed consent from subject or legally acceptable representative * NIHSS score of 6 - 22, inclusive, or at least 2 on the aphasia item of the NIHSS with a location of MRI findings consistent with aphasia MRI-determined inclusion criteria: * Acute ischemic stroke with substantial cortical involvement in the middle cerebral artery (MCA) distribution, as verified by the Screening DWI abnormality and/or Screening PWI abnormality. (Note: white matter involvement, in addition to cortex, is not an exclusion.) Exclusion Criteria: General exclusion criteria: * Two or more of the following: * Reduced level of consciousness (score \>= 2 on NIHSS Q1a) * Forced eye deviation or total gaze paresis (score of 2 on NIHSS Q2) * Dense hemiplegia (no movement) of upper and lower extremities (score of 4 on NIHSS Q5 regarding motor arm and a score of 4 on NIHSS Q6 regarding motor leg) * Pre-stroke modified Rankin score \>= 2 at Screening * Rapid neurological improvement from Screening up to the start of drug infusion * Persistent systolic blood pressure (SBP) \> 220 mmHg and/or diastolic blood pressure (DBP) \> 120 mmHg (confirmed by at least three readings taken at least 3 minutes apart) prior to randomization. If subsequent readings are consistently below these levels, either spontaneously or following mild antihypertensive therapy, subject may be enrolled. MRI-determined exclusion criteria: * Intracranial hemorrhage as verified by Screening MRI. (Note: intracranial hemorrhage on pre-screen computerized tomography \[CT\] scan also excludes subject.)