If the trial is against saline (a true placebo) the chance of success is greater than if it is against a thrombolytic that is FDA approved (TPA) for acute stroke. Intra cranial TPA is given up to 6 hours and for really bad prognosis stroke like a basilar artery thrombosis even up to 12 hrs. If the trial was done against mechanical dissolution like the concentrix device it might be harder to achieve a good result.
Just wondering. I suspect if the drug is going against a placebo the result will likely be good.