STROKE · White paper
Stroke Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About stroke — and why its trials are hard
Stroke, the sudden interruption of cerebral blood flow, is a leading cause of long-term disability and the second leading cause of death worldwide, affecting roughly 795,000 Americans each year. Most strokes are ischemic (arterial occlusion); hemorrhagic strokes carry higher mortality. Acute ischemic-stroke care rests on two pillars: intravenous thrombolysis and, for large-vessel occlusion, mechanical thrombectomy. Alteplase (tPA) was established by the landmark NINDS trial in 1996, and tenecteplase (TNKase) became the first new stroke thrombolytic in nearly three decades when the FDA approved it for acute ischemic stroke in 2025. Mechanical thrombectomy, though a device rather than a drug, transformed outcomes in trials such as DAWN and DEFUSE-3 by extending the treatment window to 24 hours in selected patients. Direct oral anticoagulants (apixaban, rivaroxaban, dabigatran) prevent cardioembolic stroke in atrial fibrillation. Efficacy is measured by functional outcome (modified Rankin Scale, NIHSS), mortality, recanalization and safety (symptomatic intracranial hemorrhage). The field is defined by a narrow therapeutic window and a long graveyard of failed neuroprotectants, most notably NXY-059 (SAINT).
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Alteplase (tPA) (Activase) | 1996 | Acute ischemic stroke within 3-4.5 hours of symptom onset | NINDS rt-PA Stroke Study (NCT00023394) | Favorable functional outcome (mRS, Barthel Index, Glasgow, NIHSS) at 3 months | ~30% higher likelihood of minimal/no disability at 3 months; ~6% increase in symptomatic intracranial hemorrhage |
| Tenecteplase (TNKase) | 2025 | Acute ischemic stroke in adults (single IV bolus); first new stroke thrombolytic in ~30 years | AcT and supporting trials (e.g., EXTEND-IA TNK); NCT02180237 | Functional independence (mRS <=2) at 90 days; reperfusion | Non-inferior/comparable to alteplase with easier bolus dosing and improved reperfusion in large-vessel occlusion |
| Mechanical thrombectomy (Endovascular clot retrieval (device, not a drug)) | 2015-2018 (guideline-defining trials) | Large-vessel occlusion ischemic stroke, extended window up to 24 hours in selected patients | DAWN; DEFUSE-3 | Functional independence (mRS) at 90 days | DAWN/DEFUSE-3 showed large functional-independence benefit versus medical therapy in imaging-selected patients |
| Apixaban (Eliquis) | 2012 | Stroke prevention in non-valvular atrial fibrillation | ARISTOTLE (NCT00412984) | Stroke or systemic embolism; major bleeding | 21% reduction in stroke/systemic embolism and 31% lower major bleeding vs warfarin; lower all-cause mortality |
| Dabigatran (Pradaxa) | 2010 | Stroke prevention in non-valvular atrial fibrillation | RE-LY (NCT00262600) | Stroke or systemic embolism | 150 mg reduced stroke/systemic embolism vs warfarin (2.2% vs 3.4%/yr, HR 0.65); hemorrhagic stroke HR ~0.26 |
| Rivaroxaban (Xarelto) | 2011 | Stroke prevention in non-valvular atrial fibrillation | ROCKET AF (NCT00403767) | Stroke or systemic embolism | Non-inferior to warfarin (HR 0.88; 95% CI 0.74-1.03); fewer intracranial hemorrhages |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in stroke development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| NXY-059 (Cerovive) — SAINT I / SAINT II | Free-radical-trapping neuroprotectant appeared positive in SAINT I but failed to improve outcomes in the larger SAINT II trial | Non-reproducible early signal; the classic example of the failed neuroprotectant paradigm and outcome-scale variability |
| Desmoteplase — DIAS program (NCT00129736) | Bat-saliva-derived thrombolytic showed insufficient 90-day functional benefit and inconsistent recanalization | Difficulty replicating natural thrombolysis with predictable pharmacodynamics and acceptable bleeding risk |
| Natalizumab — ACTION (NCT01955707) | Repurposed MS drug failed to provide neuroprotection in acute ischemic stroke | Immunomodulation risks (infection, immune suppression) outweighed benefit in a vulnerable stroke population |
Choosing the right endpoint
Primary endpoints that matter in stroke trials
- Modified Rankin Scale (mRS) at 90 days — Primary functional-outcome standard; requires centralized, blinded, standardized assessment to limit inter-rater variability
- NIH Stroke Scale (NIHSS) — Quantifies neurological deficit acutely and over time; supportive functional measure
- Recanalization / reperfusion — Imaging endpoint (TICI/clot resolution) correlating with recovery; sensitive to imaging-protocol variability
- Symptomatic intracranial hemorrhage — Critical safety endpoint for thrombolytics and anticoagulants that must be balanced against efficacy
- Mortality — Reflects life-saving impact but is confounded by comorbidities requiring stratification
How iNGENū runs stroke trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
The full white paper: approved-product analyses, pivotal endpoints and trial-design strategy. Open-access · no sign-in.
Frequently asked questions
Stroke clinical trials — FAQs
What is the primary efficacy endpoint in acute stroke trials?
Why have so many neuroprotectant drugs failed in stroke?
How did tenecteplase and thrombectomy change acute stroke care?
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