Efficacy and safety of intravenous nerinetide initiated by paramedics in the field for acute cerebral ischaemia within 3 h of symptom onset (FRONTIER): a phase 2, multicentre, randomised, double-blind, placebo-controlled study.

Background: Nerinetide is a neuroprotectant effective in preclinical models of acute ischaemic stroke when administered within 3 h of onset. However, the clinical evaluation of neuroprotectants in this short timeframe is challenging. We sought to establish the feasibility, safety, and effectiveness of nerinetide when given before hospital arrival within 3 h of symptom onset of suspected stroke.

Methods: In this multicentre, randomised, double-blind, placebo-controlled study, paramedics enrolled participants aged 40-95 years within 3 h of suspected severe stroke onset, who were previously independent, and were being taken to one of seven stroke centres in Ontario or British Columbia, Canada. The primary hypothesis was that the administration of nerinetide would result in a higher rate of good functional outcomes. Participants were randomly assigned 1:1 to intravenous nerinetide (2·6 mg/kg) or placebo, each in visually identical vials. Paramedics, hospital care providers, and outcome evaluators were masked to treatment assignment. The primary outcome was good functional outcome on a sliding dichotomy of the modified Rankin Scale at 90 days. Participants were assessed on day 4, 30, and 90 by the stroke center research team, in person or over the telephone. Outcomes, adjusted for age and stroke severity, were evaluated in the modified intention-to-treat (mITT) population, and in the target population of those with acute ischaemic stroke. The safety population included all participants who received the study drug. This study is registered with ClinicalTrials.gov (NCT02315443), and trial enrolment has concluded.

Findings: Between March 26, 2015, and March 27, 2023, 532 participants received nerinetide (n=265) or placebo (n=267). The mITT population of suspected stroke (n=507; 254 nerinetide and 253 placebo) included 321 (63%) with acute ischaemic stroke, 93 (18%) with intracranial haemorrhage, 44 (9%) with transient ischaemic attack, and 49 (10%) with stroke-mimicking conditions. Treatment began a median of 64 min (IQR 47-100) from symptom onset. Participants randomly assigned to nerinetide had more severe strokes compared with those receiving placebo (median National Institutes of Health Stroke Scale (NIHSS) 12, IQR 5-19 vs 10, 4-18 in mITT, and 14, 7-19 vs 10, 4-18 in the acute ischaemic stroke subgroup). Overall, 145 (57%) of 254 participants in the nerinetide group and 147 (58%) of 253 in the placebo group had the primary outcome of a favourable functional outcome using the prespecified sliding dichotomy at 90 days (adjusted odds ratio 1·05, 95% CI 0·73-1·51; adjusted risk ratio 1·04, 95% CI 0·85-1·25). In the 302 patients with ischaemic stroke, the favourable functional outcome adjusted for arrival NIHSS and age favoured nerinetide (odds ratio 1·53, 0·93-2·52 and risk ratio 1·21, 0·97-1·52). In those given reperfusion therapies (thrombolysis or endovascular thrombectomy, or both) nerinetide was associated with improved favourable functional outcomes (adjusted odds ratio 1·84, 1·03-3·28; adjusted risk ratio 1·29, 1·01-1·65). There was no apparent benefit in haemorrhagic stroke or acute ischaemic stroke without reperfusion. There were no safety concerns.

Interpretation: Prehospital nerinetide did not improve neurological functional outcomes in all patients with suspected ischaemic stroke in the mITT population. Nerinetide might benefit patients with acute ischaemic stroke who are selected for reperfusion therapies within 3 h of symptom onset. This finding should be confirmed in a future trial.

Funding: Brain Canada and NoNO.