Tenecteplase for Stroke Thrombolysis Up to 24 Hours?

February 16, 2022

The thrombolytic tenecteplase may have a role in reestablishing blood flow in patients with large-vessel acute ischemic stroke up to 24 hours after stroke onset selected by perfusion imaging, a new trial from China suggests.

The phase 2a CHABLIS trial was presented February 10 at the International Stroke Conference (ISC) 2022 by Xin Cheng, MD, associate professor of neurology at the Huashan Hospital of Fudan University and the National Center for Neurological Disorders in Shanghai, China.

"These results are the first to be reported with tenecteplase in the extended time window and suggest that it may be feasible to extend the time window of intravenous thrombolysis to 24 hours after last known well through perfusion imaging selection," she concluded.

Cheng noted that alteplase (tissue plasminogen activator) is the standard of care for thrombolysis in stroke, with a time window of up to 4.5 hours after stroke onset. However, the recent EXTEND trial suggested benefit of alteplase in patients who were between 4.5 and 9 hours of stroke onset and who had hypoperfused but salvageable regions of brain detected on automated perfusion imaging.

Tenecteplase is a genetically modified variant of alteplase. It has received regulatory approval for treatment of myocardial infarction. Cheng said there is increasing interest in tenecteplase as an alternative to alteplase, mainly because of its practical advantages (single bolus, rather than 1-hour infusion) and its having a number of hypothetical advantages over alteplase, including greater fibrin specificity and lesser likelihood of fibrinogen depletion.

Until now, studies of tenecteplase in stroke have included patients in the traditional time window, which has been no longer than 6 hours from stroke onset, she added.

For the current CHABLIS trial, the Chinese researchers investigated the use of tenecteplase administered to ischemic stroke patients at 4.5 to 24 hours from time of their being last seen well who were selected by significant penumbral mismatch on perfusion imaging.

The trial included 86 patients who had an anterior large-vessel occlusion or severe stenosis identified on head and neck CT angiography and penumbral mismatch on CT perfusion imaging. They were randomized to one of two doses of tenecteplase, 0.25 mg/kg or 0.32 mg/kg.

The primary outcome was the achievement of reperfusion without symptomatic intracranial hemorrhage at 24 to 48 hours after thrombolysis. This occurred in 32% of the 0.25 mg/kg group vs 23.3% of the 0.32 mg/kg group.

Recanalization at 4 to 6 hours occurred in 44% of both groups.

In terms of neurologic outcomes, an excellent functional outcome, defined as a Modified Rankin Scale (mRS) score of 0 to 1 at 90 days, was achieved in 28% of the 0.25 mg/kg group and 49% of the 0.32 mg/kg group. A good functional outcome (mRS, 0 to 2) occurred in 46% of the 0.25 mg/kg group vs 60% of the 0.32 mg/kg group.

Safety results showed that any intracranial hemorrhage (ICH) was reported in 49% of the 0.25 mg/kg group and 30% of the 0.32 mg/kg group. Symptomatic ICH occurred in 11% and 9%, respectively.

Limitations of the study included a small sample size and the lack of a control group. In addition, the study included only Chinese patients, who are known to have different stroke etiologies in comparison ro White patients, Cheng noted.

In the subset of patients who received tenecteplase and who underwent endovascular therapy, fewer patients (8.8%) reached the primary outcome measure of reperfusion without symptomatic ICH compared to those who received only tenecteplase (40.4%).

"In our study, tenecteplase seems to be quite effective and safe in patients who do not need endovascular therapy," Cheng said. "More research is needed to understand why tenecteplase was less effective in restoring blood flow and more likely to result in symptomatic brain bleeding among those who had endovascular therapy."

The researchers have now started a phase IIb trial, CHABLIS-2. This is a randomized, multicenter, controlled, open-label study of the 0.25 mg/kg dose of tenecteplase.

Commenting on the current study at an ISC press conference, Tudor G. Jovin, MD, chair of neurology at Cooper University Hospital, Cherry Hill, New Jersey, said: "This is very important study looking at the question of using thrombolysis out to 24 hours, and it does suggest a benefit, but we don't know the best dose yet."

He noted that his hospital system has already switched from alteplase to tenecteplase in the treatment of stroke, and several other centers are also making this switch.

"In our center, we use the 0.25 mg/kg dose, but we don't routinely treat patients beyond the 4.5-hour time window," Jovin reported.

"The signals are there for a longer treatment window," he said. "But this study was not aiming to directly answer whether tenecteplase is better than no treatment or alteplase, or its use with endovascular therapy."

Noting that there are similar randomized trials ongoing in the US and other countries exploring the same doses of tenecteplase, he said he thought the "dose and approach is applicable to US practice."

The CHABLIS study was funded by national key research and development program of China from the Science and Technology Ministry. Tenecteplase was provided by Guangzhou Recomgen Biotech Co.

International Stroke Conference (ISC) 2022: Abstract LBS7. Presented February 10, 2022.

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