Rationale and design of Tenecteplase Reperfusion Therapy in Acute Ischaemic Cerebrovascular Events III (TRACE III): a randomised, phase III, open-label, controlled trial

Introduction

Acute large vessel occlusion (LVO) is associated with devastating ischaemic stroke, accounting for 30%–46% of the ischaemic stroke with a 90-day mortality of 60%–80%.1–3 The current American Heart Association/American Stroke Association guidelines recommended intravenous thrombolysis bridging mechanical thrombectomy as the first-line treatment for acute LVO of anterior circulation stroke within 4.5 hours of stroke onset.4 However, a majority of patients arrive in the hospital outside the 4.5-hour time window, who could not receive intravenous thrombolysis.5 The Extending the Time for Thrombolysis in Emergency Neurological Deficits (EXTEND) trial extended the time window to 9 hours for intravenous alteplase with advanced imaging mismatch on the RAPID software (iSchemaView, USA).6 While the Efficacy and Safety of MRI-Based Thrombolysis in Wake-Up Stroke (WAKE-UP) trial proved that alteplase is beneficial for wake-up patients with diffusion-weighted imaging (DWI)—fluid-attenuated inversion recovery mismatch, the mean infarct volumes in this trial were quite small and the proportion with LVO was less than 25%, so evidence is lacking as to the benefits of alteplase in this population.7 Given that the time window for thrombectomy has been guideline-endorsed for treatment up to 24 hours in selected patients with clinical-imaging mismatch or perfusion-imaging mismatch, the optimal safety and efficacy of administration of lytics among patients in whom thrombectomy is not intended is uncertain.8 9 The Phase III, Prospective, Double-blind, Randomised, Placebo-controlled Trial of Thrombolysis in Imaging-eligible, Late-window Patients to Assess the Efficacy and Safety of Tenecteplase (TIMELESS, NCT03785678) trial will assess the efficacy of TNK versus placebo in patients with stroke due to LVO intended for thrombectomy, but include some proportion of patients who experience spontaneous or TNK associated reperfusion prior to thrombectomy.

Although alteplase has been used in clinical practice for 15 years, its main disadvantage is its delivery method of ‘a bolus followed by a drip for 1 hour’, which is inconvenient for bridging thrombectomy and ‘drip and ship’ patients due to potential for delays in transfer, unfavourable pharmacokinetics if there is a delay between bolus and infusion, higher cost and the challenges or performing MR imaging with an infusion pump. Tenecteplase (TNK) is a genetically engineered mutant tissue plasminogen activator. Compared with alteplase, TNK has a longer half-life, stronger affinity for fibrin, stronger tolerance to plasminogen activator inhibitor-1 and can be administered by a single bolus.10 The tenecteplase versus alteplase before thrombectomy for ischaemic stroke (EXTEND-IA TNK) trial revealed that TNK had higher recanalisation rate than alteplase in patients with LVO intended for thrombectomy within 4.5 hours after symptom onset.11 In China, recombinant human TNK tissue-type plasminogen activator (rhTNK-tPA) approved for treating acute myocardial infarction,12 had the same terminal amino acid sequence and different production process to the TNK made by Boehringer (Metalyse) and Genentech (TNKase).13 The TRACE (Tenecteplase Reperfusion therapy in Acute ischaemic Cerebrovascular Events) trial as the phase II trial of rhTNK-tPA found that in comparison with alteplase, Chinese patients with acute ischaemic stroke treated with rhTNK-tPA showed similar rates of improvements on neurological deficits and symptomatic intracranial haemorrhage (sICH) at all doses (0.1, 0.25, 0.32 mg/kg) administered within 3 hours of symptom onset.13 The TRACE Ⅱ trial has demonstrated that rhTNK-tPA 0.25 mg/kg received within 4.5 hours of stroke onset is non-inferior to alteplase 0.9 mg/kg for patients with AIS in China (NCT04797013).14 However, the efficacy and safety of rhTNK-tPA 0.25 mg/kg beyond 4.5 hours is unknown.

Therefore, we conducted the TRACE III trial and aimed to investigate the efficacy and safety of rhTNK-tPA 0.25 mg/kg within the time window of 4.5–24 hours, wake-up stroke or no witness stroke in patients who had an ischaemic stroke with salvageable tissue due to LVO.

Methods

Patient population

Adult patients with AIS due to culprit anterior circulation LVO (internal carotid artery, middle cerebral artery M1 and M2 segments) within 4.5–24 hours from last known well (including wake-up stroke and no witness stroke) and with salvageable tissue (ischaemic core volume <70 mL, mismatch ratio ≥1.8 and mismatch volume ≥15 mL) based on CT perfusion or MRI PWI were consecutively enrolled into this trial. Patients who had intention to proceed to endovascular treatment were excluded. The detailed inclusion and exclusion criteria were shown in figure 1.

Figure 1

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Detailed inclusion and exclusion criteria. MCA, middle cerebral artery; rhTNK-tPA, recombinant human TNK tissue-type plasminogen activator; APTT, activated partial thromboplastin time.

Outcomes and follow-up

Study visits will be performed at the screening period (4.5–24 hours before thrombolytic therapy), 0 hour (thrombolytic therapy), 24 hours, 36 hours, 72 hours, day 7 or before discharge (the earliest or latest occurrence among these two will be judged as the follow-up point) and day 90 (endpoint). (figure 2) At the screening period, CT+CTA +CTP (or MRI_DWI+MRA + PWI) should be performed. At 24 hours of randomisation, CT+CTA + CTP (or MRI_DWI+MRA + PWI) should be completed to assess recanalisation. The follow-up imaging (CT or MRI) should be completed within 24–36 hours to detect intracranial haemorrhage. At baseline and during follow-up visits, clinical information (not limited to that) including the neurological examination (NIHSS and mRS score), vital signs, concomitant medications, adverse events (AEs) and serious AEs (SAE) will be collected (figure 3).

Figure 2

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Study flow chart. AIS, acute ischaemic stroke; CTP, CT perfusion; ICA, intracranial cerebral artery; MCA, middle cerebral artery; NIHSS, National Institute of Health Stroke Scale; rhTNK-tPA, recombinant human TNK tissue-type plasminogen activator.

Figure 3

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Trial assessment flow chart. DWI, diffusion-weighted imaging; mRS, modified Rankin Scale.*Key time points include onset time, hospitalization time and thrombolysis time; †The baseline blood pressure test is collected at the time of vital signs collection; The "Oh" visit is regarded as within 5 minutes before thrombolysis; Vital signs include blood pressure, pulse, temperature and respiratory rate; ‡The mRS scores screened into the group include premorbid score and post-onset score before thrombolysis; §Pregnancy test is limited to female subjects of childbearing age; ¶Laboratory assessments: Baseline laboratory assessments include hematology, clinical chemistry and coagulation profile; No need to repeat the assessments performed after the attack and before thrombolysis. Fasting blood is required for the baseline lipid profile (total cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides). Fast glucose is allowed to decide eligibility criteria with serum glucose collected synchronously. The clinical chemistry results are available after the administration of study drugs. The investigators will deal with the abnormal results according to guidelines and the clinical pathway if necessary. (1) The laboratory assessments of 72h after thrombolysis, including hematology, clinical chemistry, coagulation profile and urinalysis, can be acceptable for the 24h visit. (2) Hematology, clinical chemistry, coagulation profile and urinalysis should be done at 7±1 days or before discharge (whichever occurs first). **No need to repeat ECG after the attack and before thrombolysis; ‡‡The baseline imaging, whatever "CT or MRI", is used to exclude intracranial hemorrhage. CT angiography (CTA)+ CT perfusion (CTP) or MRI perfusion weighted imaging (MRI_PWI) +MR angiography (MRA) was used to identify large vessel occlusion and target mismatch. The follow-up imaging CT +CTA + CTP (or MRI_DWI +MRA + PWI) need to be completed at 24 + 6h of randomization to assess vessel recanalization and tissue reperfusion. CT or MRI need to be completed within 36 ± 6h to detect intracranial hemorrhage, if patient's sign remain stable, then 24 ± 6h CT or MRI can be used as the evaluation imaging for intracranial hemorrhage and no need to repeat the CT or MRI at 36 ± 6h. §§Thrombolysis information includes the time of thrombolytic therapy in treatment group (including the intravenous bolus time, the dose of the bolus and the adverse events).

If SAEs or suspicious and unexpected serious adverse reactions (SUSAR) occur, investigators should adhere to the protocol and Good Clinical Practice guidelines. The Endpoint Adjudication Committee (EAC) will adjudicate the report. The AEs, SAEs and SUSAR will be reported using standard tabulated terminology.

Discussion

As far as we know, our trial is the first phase Ⅲ, randomised clinical trial of rhTNK-tPA in the late window of 4.5–24 hours, wake-up or no witness in patients who had a stroke due to LVO that are not intended for endovascular treatment. This will allow us to exclusively answer the question of efficacy and safety of rhTNK-tPA comparing with standard medical treatment in patients with LVO out of direct endovascular treatment at initial assessment.

In high-income countries such as Western Europe, USA and Australia, the time window has been extended to 24 hours for thrombectomy based on advanced imaging modalities and patients have the opportunity to receive thrombectomy outside the intravenous thrombolysis time window. However, for many patients in low-income or middle-income countries, thrombectomy is not an option due to the financial burden, and the lack of routinely available advanced perfusion imaging and automated software for interpretation. Intravenous thrombolysis is the global foundational therapy for acute ischaemic stroke management, as it is more affordable, requires little training to administer and is readily available. However, only 24.4% patients received intravenous thrombolysis within the time window of 4.5 hours in China based on the China Stroke Statistics 2019.19 and the recanalisation rate using alteplase alone in LVO was only 10%.11 Comparing with alteplase, TNK has superior pharmacodynamic and pharmacokinetic properties and might have great application prospects, especially for patients who need to be transferred to a distant centre for thrombectomy.

Echoplanar Imaging Thrombolytic Evaluation Trial20 and Diffusion and perfusion imaging Evaluation For Understanding Stroke Evolution (DEFUSE) studies21 confirmed that PWI/DWI mismatch could predict favourable outcome after IV tPA therapy within 3–6 hours including a higher rate of recanalisation, better reperfusion, slower infarct progression and a higher percentage of mRS 0–1. In addition, DEFUSE also indicated that a large DWI volume (>100 mL) is a predictor of sICH.21 CTP is another imaging method to assess mismatch to evaluate ischaemic penumbra. EXTEND trial used a CTP target imaging mismatch and demonstrated that IVT tPA within 4.5–9 hours could improve reperfusion and clinical functional outcome.6 However, in EXTEND trial,6 large artery occlusion was not a prerequisite for inclusion and its target imaging mismatch criteria was not applicable in our trial. DEFUSE 3 trial included patients with ischaemic stroke due to LVO of anterior circulation.9 In the DEFUSE 3 trial, another CTP target imaging mismatch (core volume is <70 mL, mismatch ratio is ≥1.8 and mismatch volume is ≥15 mL) was established to select patients that could benefit from mechanical thrombectomy within 6–16 hours from last known well due to LVO in the anterior circulation. Hence, we used the target imaging mismatch of DEFUSE 3 in our trial.

While a double-blind randomised, placebo controlled trial design would be ideal for a definitive phase III clinical trial to avoid potential bias and balance confounders in the study, we were unable to secure a reliable source of rhTNK-tPA placebo. Hence, we opted to conduct a PROBE design, and will rely on the blinding of the assessors to prevent the exposure of treatment allocation which could introduce bias.

Currently, the evidence of TNK in the later time window is limited. The Tenecteplase in Wake-up Ischaemic Stroke Trial (TWIST) found that treatment with tenecteplase within 4.5 hours of awakening did not lead to better functional outcome at 90 days in patients with wake-up stroke. The rates of sICH or any ICH were not significantly different between tenecteplase thrombolysis and no thrombolysis. However, eligible patients were mainly selected based on non-contrast CT in the trial.22 The Tenecteplase versus Alteplase for Acute Ischaemic Stroke, also referred to the Australian-TNK trial, used CTA and CTP to select eligible patients within 6 hours from last known well and demonstrated the benefits of TNK over alteplase in recanalisation and functional outcome. And there were no significant between-group differences in intracranial bleeding or other SAEs.23 Considering this is a phase II trial with a relatively small sample size, large sample phase Ⅲ is warranted. To investigate the effectiveness and safety of rhTNK-tPA beyond 4.5 hours, we initiated this TRACE III trial with CTP or PWI as selection tools. Other trials are ongoing in the world to provide more evidence on TNK beyond 4.5 hours (TIMELESS) NCT03785678; Extending the Time Window for Tenecteplase by Effective Reperfusion in Patients With LVO (ETERNAL-LVO), NCT04454788). Compared with the ongoing trials, TRACE Ⅲ is a unique phase Ⅲ trial of rhTNK-tPA versus standard medical treatment in AIS patients with anterior circulation LVO and salvageable tissue ischaemic stroke beyond 4.5 hours but without intention to endovascular treatment at initial assessment.

In conclusion, TRACE III is initiated to investigate the efficacy and safety of TNK beyond 4.5 hours in patients with acute ischaemic stroke due to LVO. It will help provide evidence for TNK use in time window of 4.5–24 hours.