However, there were some encouraging trends, and there did not appear to be an increase in intracranial hemorrhage (ICH), leading to hope that the option of late thrombolysis in this group of patients may still have potential.
The TIMELESS study tested the approach of giving thrombolysis with tenecteplase (TNK) to patients with a large-vessel occlusion stroke up to 24 hours after symptom onset. Patients were selected by perfusion imaging, and those who had a stroke with a small core and large amount of salvageable brain tissue were included in the placebo-controlled study.
“This is first trial to try giving a thrombolytic so late – up to 24 hours after last known well. While we did not meet the primary outcome, there were some promising findings,” lead author, Gregory Albers, MD, director of the Stanford (Calif.) Stroke Center and professor of neurology at Stanford University, said in an interview.
“The most encouraging observation was that we did not show any safety issues with giving TNK to this population at such a late time. Many people thought this would be too high risk but there was no increase in ICH, which was very low and the same in both groups,” Dr. Albers said.
“And we saw some evidence of drug effect. There appeared to be a benefit in patients with M1 occlusions, the most common type of large-vessel occlusion, who represented half the patients in the study,” he added.
The researchers also gained information on the logistics and timing of TNK administration in this late period which they hope can guide the design of a future trial.
Dr. Albers presented the TIMELESS trial at the annual European Stroke Organisation Conference.
He explained that there is increasing evidence that intravenous thrombolysis can improve outcome in selected patients even beyond the traditional 4.5-hour time window.
The phase 3, double-blind, randomized, placebo-controlled TIMELESS study sought to investigate whether tenecteplase administered to patients with ischemic stroke with large-vessel occlusion presenting between 4.5 and 24 hours after last known well would improve clinical outcome as measured by modified Rankin Scale (mRS) at day 90.
The trial included 458 patients with an internal carotid artery occlusion or middle cerebral artery segment 1 or 2 occlusion and presenting with salvageable tissue on imaging. They were randomly assigned 1:1 to either intravenous tenecteplase (0.25 mg/kg; maximum, 25 mg) or placebo.
The proportion of patients treated with mechanical thrombectomy were similar between the two treatment arms (around 77%). The study completion rate was higher than 96% in both treatment arms.
The primary endpoint analyses showed no significant difference in the odds of a lower mRS score at day 90, but there was a slight trend toward benefit in the TNK group in the shift analysis, with a common odds ratio of 1.13 (95% confidence interval, 0.81-1.56; P = .48).
The percentage of patients achieving a favorable outcome, defined as an mRS of 0-2, was not significantly different between the treatment groups: 46% in the TNK group versus 42% in the placebo group (nominal P = .41).