RNS60 RESCUE Trial in Acute Ischemic Stroke: Post Hoc Analysis in Participants Enrolled <12 Hours Since Last Known Well

Abstract

BACKGROUND:

Adjunct therapies are needed for patients with acute ischemic stroke who fare poorly, despite standard-of-care endovascular thrombectomy (EVT). RESCUE (A Randomized, Blinded, Placebo-Controlled, Parallel Group Design to Determine the Safety of RNS60 in Large Vessel Occlusion Stroke Patients Undergoing Endovascular Thrombectomy) tested the cytoprotective experimental drug RNS60 in patients with acute ischemic stroke, adjunct to EVT with or without prior standard-of-care thrombolytic treatment.

METHODS:

RESCUE, a randomized, placebo-controlled, double-blind, phase 2 study, enrolled 83 participants eligible for EVT within 24 hours since last known well, assigned 1:1:1 to 48-hour infusion of RNS60 0.5 mL/kg per hour, RNS60 1.0 mL/kg per hour, or placebo 1.0 mL/kg per hour. A post hoc analysis evaluated safety and efficacy in a subpopulation of 62 participants enrolled within 12 hours since last known well. Efficacy end points included modified Rankin Scale score, post-EVT infarct growth, National Institutes of Health Stroke Scale score, Barthel Index score, EuroQoL, and duration of hospitalization and discharge disposition.

RESULTS:

In this subpopulation, RNS60 1.0 mL/kg per hour was generally safe and well tolerated and reduced post-EVT infarct growth compared with placebo (least squares mean difference, 22.2; P=0.05). Of the participants treated with RNS60 1.0 mL/kg per hour, 72.2% achieved a 90-day modified Rankin Scale score of 0 to 2, and 72.2% achieved a Barthel Index score ≥95, compared with 36.8% (for both measures) of those receiving placebo, although the differences were not statistically significant (P=0.09 for both modified Rankin Scale and Barthel Index scores). Consistent but smaller differences to placebo were seen in the RNS60 0.5 mL/kg per hour group, which suggests a dose-dependent effect of RNS60. Participants in the RNS60 1.0 mL/kg per hour group were also released earlier from the hospital than those in the placebo group (mean [SD]: 6.0 [5.10] days versus 10.8 [6.84] days; mean difference [SE], −4.8 [1.99]; P=0.02). Final infarct volumes at 48 hours post-EVT correlated with modified Rankin Scale scores at day 90 for RNS60 1.0 mL/kg per (Pearson r=0.65; P=0.005) and placebo (r=0.65; P=0.007).

CONCLUSIONS:

Effects of RNS60 were favorable compared with placebo in the analyzed subpopulation, warranting further investigation in this population.

REGISTRATION:

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04693715.

GRAPHIC ABSTRACT:

CLINICAL PERSPECTIVE.

What Is New?

• RESCUE (A Randomized, Blinded, Placebo-Controlled, Parallel Group Design to Determine the Safety of RNS60 in Large Vessel Occlusion Stroke Patients Undergoing Endovascular Thrombectomy), a phase 2 trial, tested the investigational new drug RNS60 in patients with acute ischemic stroke enrolled in <24 hours since last known well, adjunct to endovascular thrombectomy with or without prior standard-of-care thrombolytic treatment.

• In this post hoc analysis, RNS60 1.0 mL/kg per hour was generally (1) safe and well tolerated, (2) showed consistent and more pronounced effects on multiple end points in the subpopulation enrolled in <12 hours since last known well; this warrants future testing of RNS60 in this patient population.

What Are the Clinical Implications?

• Adjunct therapy with RNS60 could improve outcomes for patients with acute ischemic stroke and large vessel occlusion undergoing endovascular thrombectomy.

Acute ischemic stroke (AIS) remains a leading cause of death and significant long-term disability.^1,2 Although there have been advances in reperfusion therapies, most notably endovascular thrombectomy (EVT) for those with large vessel occlusion (LVO), a large proportion of patients with LVO still fail to achieve functional independence. There is a need for adjunctive neuroprotective strategies to extend the therapeutic window and to bolster the effectiveness of reperfusion.

RNS60, oxygen supersaturated in saline with a proprietary technology that involves modified Taylor-Couette-Poiseuille flow, is a candidate for adjunctive therapy in AIS. Preclinical studies have shown that RNS60 exerts cerebroprotective effects via activation of the type 1A PI3K-Akt (phosphatidylinositol 3-kinase–protein kinase B) pathway, which leads to neuronal survival under stress, suppression of glial inflammation, and improved mitochondrial function.^3–6 Of particular interest to stroke, RNS60 has attenuated reperfusion injury and preserved penumbral tissue, in mouse and nonhuman primate models of AIS, improving functional recovery.^7,8 RNS60 administration was generally safe and well tolerated in healthy volunteers and in study participants with relapsing remitting multiple sclerosis, amyotrophic lateral sclerosis, and AIS.^9–13

The primary analysis of the proof-of-concept phase 2 trial (RESCUE [A Randomized, Blinded, Placebo-Controlled, Parallel Group Design to Determine the Safety of RNS60 in Large Vessel Occlusion Stroke Patients Undergoing Endovascular Thrombectomy]) showed that RNS60 was safe and well-tolerated in patients with AIS with LVO undergoing standard-of-care EVT and thrombolytic treatment for eligible participants. Further, RNS60 1.0 mL/kg per hour reduced infarct growth between 2 and 48 hours after EVT compared with placebo.¹³ Because cerebroprotective therapies are more likely to be of the greatest benefit when administered as early as possible,^14,15 post hoc analyses of the RESCUE trial subpopulation enrolled within 12 hours since last known well (LKW) were conducted to aid in defining the target population for a future trial powered to confirm the RESCUE results and establish evidence of effectiveness of RNS60 as an adjunct treatment for LVO AIS.

Methods

Data will be made available on reasonable request via email (info@revalesio.com). The study results are reported according to the CONSORT guidelines (Consolidated Standards of Reporting Trials; Supplemental Material).

Study Design and Participants

This study was a post hoc analysis of the RESCUE trial, which was a phase 2, multicenter, randomized, parallel-group, placebo-controlled, blinded-assessor study in participants with LVO stroke who were eligible for EVT. The rationale and methods of this proof-of-concept trial have been described previously in detail.¹³ Briefly, the primary objective was to determine the safety of RNS60 treatment and assess efficacy with secondary end points.

Five US comprehensive stroke centers obtained institutional review board approvals before participant enrollment. The study was conducted in accordance with all applicable laws and regulations, and in compliance with Good Clinical Practice and in accordance with the Declaration of Helsinki. Before the performance of any study procedures, informed consent was obtained from all participants or their legally authorized representatives.

Participants enrolled within 24 hours since LKW were randomized 1:1:1 to RNS60 0.5 mL/kg per hour, RNS60 1.0 mL/kg per hour, or placebo 1.0 mL/kg per hour. This post hoc analysis included participants who underwent randomization within 12 hours since LKW. All trial participants were adults at least 18 years of age with anterior circulation LVO selected for EVT. The full inclusion/exclusion criteria were previously described.¹³ Study treatment was administered via intravenous infusion initiated before the completion of the EVT procedure (arterial access closure) and continued for 48 hours. Qualifying imaging was obtained within ≈3 hours before randomization. After treatment, participants were assessed at prespecified time points until discharge and followed for 90 days.

Eligible participants were required to have confirmed symptomatic intracranial occlusion at ≥1 of the following locations: intracranial carotid I/T/L, M1 or M2 segment middle cerebral artery, with an Alberta Stroke Program Early Computed Tomography Score of ≥5; a baseline National Institutes of Health Stroke Scale (NIHSS)¹⁶ score of ≥5 for internal carotid artery and M1–middle cerebral artery occlusion or of ≥10 for M2–middle cerebral artery occlusion; and were required to be functionally independent before the stroke (defined as a modified Rankin Scale [mRS] score ≤2).^17,18

Candidate participants were excluded if they had a severe or fatal comorbid illness, a known seizure at the time of stroke onset, an ischemic stroke within the previous 30 days, evidence of absence of collateral circulation on qualifying imaging, an intracranial hemorrhage, a mass lesion, evidence suggesting the intracranial occlusion was chronic, or a suspected intracranial dissection. Also, individuals who had already completed an EVT procedure, had a myocardial infarction within the previous 6 months, presented with normal sinus rhythm with evidence of QT prolongation, or had been diagnosed with congestive heart failure or renal impairment requiring dialysis were excluded.

Procedures and Assessments

Treatment with RNS60 or placebo was administered via a 48-hour continuous intravenous infusion that started before completion of the EVT procedure by arterial access closure. Magnetic resonance imaging (MRI) of the head with perfusion imaging was performed within ≈2 hours and at 48±4 hours post-EVT; an MRI of the head was performed again on day 90. Clinical assessments were performed on day 30 and day 90. Adverse events (AEs) and mortality were monitored throughout the study.

The mRS,^17,18 NIHSS,¹⁶ and Barthel Index (BI)^19,20 scores were analyzed at baseline and day 90. The EuroQoL Health-Related Quality-of-Life Scale (EQ-5D-5L)^21,22 was assessed on day 90. Measured by MRI, infarct progression/regression was calculated by comparing the immediate (2 hours) post-EVT MRI with the 48-hour MRI. A blinded review quantitatively analyzed infarct core volume at each imaging time point by defining a region-of-interest on each axial image and calculating a total lesion volume. The change in infarct volume from 2 hours post-EVT to 48 hours post-EVT was modeled using ANCOVA for AVAL, the measurement of infarct volume in milliliters (log transformed) or change from baseline (from standard values, not log transformed). Two-sided P values were calculated.

Outcomes

For this post hoc analysis, safety end points included serious AEs and 90-day mortality in the <12 hours since LKW subpopulation. Efficacy end points included disability based on the mRS score at day 90 as a binary outcome (0–2 versus 3–6), infarct volume progression/regression at 48 hours, NIHSS score at day 90, the proportion of participants with worsening of stroke over 48 hours/duration of admission, BI score at day 90 (≥95 versus <95), and the EQ-5D-5L at day 90. Stroke worsening was defined as progression, hemorrhagic transformation of the index stroke (documented by brain imaging) with or without any of the following: (1) was life-threatening requiring intervention, (2) resulted in increased disability as gauged by a ≥4-point increase from the lowest NIHSS score during hospitalization, (3) resulted in death.

Statistical Analysis

Continuous data were summarized descriptively, while categorical and count variables were summarized by the number and percentage of participants. All analyses were performed using SAS software (SAS Institute) version 9.4 based on treatment groups assigned at randomization. Baseline was defined as the last measurement before initiation of the study drug infusion; baseline infarct volume was derived from the initial MRI obtained at 2 hours post-EVT.

Efficacy post hoc analyses were conducted in the subpopulation enrolled within 12 hours since LKW of the intent-to-treat population, which included all those randomized who received the study drug. Efficacy hypotheses were tested at a 2-sided α of 0.05; RNS60 1.0 mL/kg per hour was hypothesized to result in lower disability, and analyses were not corrected for multiple testing.

Generalized linear mixed models were used for the analyses of disability based on mRS score, worsening of stroke, and BI score (Table S1). Infarct volume, NIHSS, and EQ-5D-5L (day 90) were assessed via ANCOVA analyses. Efficacy across all key end points was assessed by comparisons between treatment arms (RNS60 1.0 mL/kg per hour versus placebo and RNS60 0.5 mL/kg per hour versus placebo). All analyses were implemented using covariates of age, baseline Alberta Stroke Program Early Computed Tomography Score binary factors used for block urn randomization, baseline NIHSS score, log of baseline infarct volume, baseline perfusion status, and baseline occlusion location, with study site as a random effect.

Missing data for the 90-day mRS score, infarct volume, BI score, and NIHSS score were managed with an assumption of missing at random. Participants who died during the study were given the worst case score for remaining visits: 6 for mRS, 42 for NIHSS, and 0 for BI.

Analyses were also performed for mRS employing a mixed model for repeated measures on continuous data using the same covariates as the dichotomous model.

A responder analysis to assess the association of combined improvement in mRS, BI, and NIHSS scores was performed, with thresholds of mRS score 0 to 2, BI score ≥95, and NIHSS score 0 to 1. The distribution of participants with and without all clinical measure scores within this range at 90 days was assessed separately for RNS60 1.0 mL/kg per hour versus placebo and RNS60 0.5 mL/kg per hour versus placebo using a χ² test as implemented in the SAS proc freq procedure. An exploratory discharge analysis assessing the difference in days spent in the hospital was performed for RNS60 1.0 mL/kg per hour versus placebo. The difference in the mean days spent in the hospital between the groups was assessed using a t test.

A Spearman correlation analysis was performed on infarct volume at 48 hours correlated to mRS, NIHSS, and BI score parameters at day 90 as implemented in SAS using the proc corr call.

Results

Study Population

This post hoc analysis evaluated the effects of RNS60 in a subpopulation of 62 participants enrolled within 12 hours since LKW of the total 83 participants enrolled and randomized in the RESCUE trial between July 2021 and November 2023 (Figure 1).

Figure 1.

Participant flow chart for subpopulation <12 hours since last known well. CT indicates computed tomography; EVT, endovascular thrombectomy; and ITT, intent-to-treat. ^aOne participant was randomized but did not receive the study drug. ^bDischarged before infusion completed (n=1); infusion ended 1 hour 44 minutes early due to miscommunication (n=1); participant left hospital against medical advice before infusion completed (n=1); study drug unavailable onsite (n=1); adverse event (n=1). ^cThe infusion for 1 participant ended early before floor transfer due to tube/ bag contamination at the site (not due to manufacturing issues). ^dOne participant signed out against medical advice. ^eSerious adverse event (death of participant). ^fFor the per-protocol population: 1 participant was excluded from RNS60 1.0 mL/kg per hour (received unknown study drug/placebo intravenous bag), and 1 excluded from the placebo group (met exclusion criteria).

In the <12 hours since LKW subpopulation, there were more male than female participants, and the mean age was 67.8 years (Table 1). The overall demographics were similar to the main intent-to-treat population enrolled within 24 hours since LKW. There were some imbalances across the 3 treatment groups with respect to thrombolytic use (64.0%, 50.0%, and 42.1% in RNS60 0.5 mL/kg per hour, RNS60 1.0 mL/kg per hour and placebo, respectively) and baseline NIHSS values (mean [SD] 15.2 [6.35], 14.3 [4.50] and 16.4 [5.99] in RNS60 0.5 mL/kg per hour, RNS60 1.0 mL/kg per hour and placebo, respectively). However, post-EVT successful reperfusion rates (as determined by post-EVT Thrombolysis in Cerebral Infarction scores of 2b, 2c, and 3) were well balanced between the 3 groups (100%, 94.4%, and 94.4% in RNS60 0.5 mL/kg per hour, RNS60 1.0 mL/kg per hour, and placebo groups, respectively). Time since LKW was similar between groups (mean [SD], 5.0 [2.5], 6.2 [3.30], and 6.1 [3.05] hours in RNS60 0.5 mL/kg per hour, RNS60 1.0 mL/kg per hour and placebo, respectively).

Table 1.

Participant Characteristics by Treatment Group for the <12 Hours Since Last Known Well Subpopulation

Safety

Most treatment-emergent AEs (91.9%) occurred within the first 7 days of the study. Headache (38.9%), constipation (33.3%), and dysphagia (16.7%) were the most common treatment-emergent AEs (≥15%) in the RNS60 1.0 mL/kg per hour group reported during week 1 compared with hypokalemia (31.6%), constipation and hemorrhagic transformation stroke (both 26.3%), hypophosphatemia (21.1%), and stroke in evolution, brain edema, anal incontinence, hypocalcemia, urinary incontinence, pleural effusion, and arthralgia (all 15.8%) in the placebo group. Constipation (20.0%), dysphagia (16.0%), and urinary retention (16.0%) were the most common treatment-emergent AEs (≥15%) in the RNS60 0.5 mL/kg per hour group reported during week 1.

The incidence of serious AEs was similar among the treatment groups (Table 2); only 1 serious AE of seizure (RNS60 0.5 mL/kg per hour group) was attributed as possibly related to the study drug, though the study drug infusion was not interrupted. There were 6 unrelated treatment-emergent AEs leading to death: 2 (11.1%) in the RNS60 1.0 mL/kg per hour group and 4 (21.1%) in the placebo group. No deaths occurred in the RNS60 0.5 mL/kg per hour group. At day 90, most participants were still alive across groups (16/18, 88.9% in RNS60 1.0 mL/kg per hour; 25/25, 100% in RNS60 0.5 mL/kg per hour; 15/19, 78.9% in placebo).

Table 2.

Summary of Treatment-Emergent Adverse Events for the <12 Hours Since Last Known Well Subpopulation

Efficacy

Key results from post hoc analyses of secondary efficacy outcomes are summarized in Table 3. At day 90, 72.2% of participants in the RNS60 1.0 mL/kg per hour group had an mRS score of 0 to 2 (functional independence), compared with 36.8% in the placebo group and 52.0% in the RNS60 0.5 mL/kg per hour group. The full distribution of mRS scores is depicted in Figure 2A. Continuous analysis of the full ordinal scale showed a least squares (LS) mean difference of −1.13 in mRS score between RNS60 1.0 mL/kg per hour group and placebo (P=0.02) and −0.54 between RNS60 0.5 mL/kg per hour and placebo (P=0.22).

Table 3.

Secondary Efficacy End Point Results

Figure 2.

Graphical representation of key efficacy findings. A, Distribution of modified Rankin Scale (mRS) participant percentage at day 90. Participants who died have been imputed to have an mRS score of 6. B, Change in infarct progression/regression over 48 hours of dosing, measured by magnetic resonance imaging (MRI) of the brain. The change in infarct volume was calculated by comparing 48-hour images to baseline images acquired by MRI 2 hours after endovascular thrombectomy and analyzed on a log scale between the 3 treatment groups using a generalized linear model. Error bars represent the SEM. C, Summary of post hoc analysis for RNS60 1.0 mL/kg per hour <12 hours since last known well subpopulation. T scores presented are representative of the analysis of the treatment indicated relative to placebo. *T scores in the graph have been reversed to be directionally consistent. EQ-5D-5L indicates EuroQoL Health-Related Quality-of-Life Scale; EVT, endovascular thrombectomy; and LS, least squares.

The LS mean (SE) change from post-EVT baseline in infarct volume values at 48 hours was 20.1 mL (10.40) for RNS60 1.0 mL/kg per hour, 24.34 mL (8.69) for RNS60 0.5 mL/kg per hour, and 42.30 mL (10.01) for placebo. Model estimates from the analysis of the change from baseline to 48-hour infarct volume indicated a significant reduction in the infarct growth in the RNS60 1.0 mL/kg per hour group (LS mean difference, −22.2; P<0.05 compared with placebo; Figure 2B). Consistently, the RNS60 0.5 mL/kg per hour group demonstrated a trend toward improvement compared with the placebo group (P=0.08).

The LS mean (SE) difference in the NIHSS score for the RNS60 1.0 mL/kg per hour group compared with placebo at day 90 was −6.16 (3.70); P=0.10. NIHSS scores numerically favored the RNS60 1.0 mL/kg per hour group compared with placebo (−11.0 versus −8.5 change from baseline on day 90, respectively). A similar pattern was observed in the RNS60 0.5 mL/kg per hour group compared with placebo.

No differences were observed among the RNS60 groups and placebo for worsening of stroke (as defined by progression, or hemorrhagic transformation of the index stroke, as documented by brain imaging, and that [1] was life-threatening requiring intervention or [2] resulted in increased disability as gauged by a ≥4-point increase from lowest NIHSS score predecline or [3] resulted in death).

At day 90, 72.2% of participants receiving RNS60 1.0 mL/kg per hour had a BI score ≥95 (functional independence) compared with 36.8% of participants who received placebo (P=0.13) and 48.0% of participants who received RNS60 0.5 mL/kg per hour. Continuous analysis also showed an LS mean difference of 24.7 in the BI score between RNS60 1.0 mL/kg per hour and placebo (P=0.01) and a 21.5 difference between RNS60 0.5 mL/kg per hour and placebo (P=0.02).

The LS mean (SE) EQ-5D-5L index scores at day 90 were 0.79 (0.13) in the RNS60 1.0 mL/kg per hour group, 0.56 (0.12) in the RNS60 0.5 mL/kg per hour group, and 0.57 (0.14) in the placebo group, respectively. RNS60 1.0 mL/kg per hour had an LS mean difference of 0.21 compared with placebo (P=0.07), and RNS60 0.5 mL/kg per hour had an LS mean difference of −0.02 compared with placebo (P=0.89).

Responder Analysis

Participants who had all 3 functional outcome measures (mRS score 0–2, BI score ≥95, and NIHSS score 0–1) read out in favor of RNS60 at day 90 were considered definite responders. There were more responders in the RNS60 1.0 mL/kg per hour group (56%) than in the placebo group (31%), but the difference was not significantly different (P=0.15). The RNS60 0.5 mL/kg per hour group had 27% responders.

Discharge Analysis

Participants treated with RNS60 1.0 mL/kg per hour (n=18) were released from the hospital significantly earlier than participants who received placebo (n=19), with a mean number of days in the hospital (SD) of 6.0 (5.10) versus 10.8 (6.84) days, respectively, and a mean difference (SE) versus placebo of −4.8 (1.99 [95% CI, −8.8 to −0.7]; P=0.02). More RNS60 1.0 mL/kg per hour and RNS60 0.5 mL/kg per hour group participants were discharged to home than participants who received placebo (10 [55.6%] versus 14 [56.0%] versus 4 [21.1%], respectively; P=0.03 for RNS60 1.0 mL/kg per hour versus placebo and P=0.02 for RNS60 0.5 mL/kg per hour versus placebo).

Correlation Analysis

Correlation of final infarct volume at 48 hours to mRS score at day 90 was strong and significant for RNS60 1.0 mL/kg per hour (Pearson r=0.65 and P=0.005) and for placebo (r=0.65 and P=0.007; Figure S1; Table 4). Similar patterns were also observed for NIHSS and BI scores at day 90 (Table 4).

Table 4.

Correlation of Infarct Volume at 48 Hours to mRS, NIHSS, and BI Scores at Day 90 for the <12 Hours Since LKW Subpopulation

Discussion

The subpopulation of RESCUE participants enrolled within 12 hours of symptom onset (≈75% of the entire study population) tolerated RNS60 well. The post hoc analyses presented here also showed a consistent and larger response to RNS60 1.0 mL/kg per hour treatment in this subpopulation compared with the full intent-to-treat population enrolled within 24 hours since LKW, in which RNS60 1.0 mL/kg per hour reduced infarct growth post-EVT relative to placebo, numerically improved mRS and BI scores, and quality-of-life as measured by EQ-5D-5L, as reported earlier.¹³ A responder analysis revealed that the number of participants with a favorable score in all 3 functional outcomes (eg, mRS score 0–2, BI score ≥95, and NIHSS score 0–1) on day 90 (definite responders) was 24% higher in the RNS60 1.0 mL/kg per hour group than in the placebo group. Consistent with the numerical improvements reported in functional outcomes, RNS60 1.0 mL/kg per hour also shortened participants’ hospital stay by an average of 4.8 days (P=0.02) and increased the discharge rate to home compared with placebo (55% versus 21%, respectively; P=0.03).

Although the data presented here are from the post hoc analysis of a phase 2 trial that was not powered for efficacy, the results are encouraging. RNS60 1.0 mL/kg per hour dose achieved a significant reduction in post-EVT infarct volume growth at 48 hours compared with placebo, despite the small group sizes. As shown by multiple imaging studies, there is significant expansion of the infarct even after successful reperfusion by EVT.^23,24 A meta-analysis with pooled data from 7 large EVT trials in anterior circulation LVO in AIS (imaging and clinical data from 1665 patients) demonstrated the predictive relationship between 48-hour infarct volume and likelihood of good clinical outcome (mRS scores 0–2) on day 90.^25,26 It has been suggested that final infarct volume can partially predict mortality at 90 days in patients with NIHSS scores <16.²⁷ Infarct volume has previously been associated with the chance of a good outcome in patients with moderate-to-large infarcts (between 15 mL to 200 mL in volume).²⁸ RNS60 significantly reduced infarct growth after EVT and thus kept the 48-hour infarct volume in check, which therefore can be expected to translate into improved functional outcomes on day 90. The main challenge in making comparisons between baseline and follow-up images at various times post-EVT in imaging trials has been the multiple imaging modalities used at various times in these trials.²⁶ However, in RESCUE, MRI imaging was performed at baseline and 48 hours post-EVT for measuring infarct sizes, and the images were evaluated by independent, blinded and trained readers.

In alignment with prior research suggesting that final infarct volume after intra-arterial stroke therapy correlates with day 90 mRS score and is a critical determinant of 3-month functional outcome,²⁹ the final infarct volume at 48 hours in the study subpopulation correlated with multiple clinical outcomes (mRS, NIHSS, and BI scores) at 90 days. A higher proportion of participants treated with RNS60 1.0 mL/kg per hour was more likely to be independent (as indicated by mRS score 0–2 or BI score ≥95) than those treated with placebo. The proportion of participants achieving an mRS score of 0 to 2 (72.2%) in this subpopulation was numerically higher than that observed in the entire intent-to-treat population enrolled within 24 hours since LKW or in other recent trials with other adjuvant cytoprotective treatments.^13,30,31 It is noteworthy that although the dichotomized analyses did not reach statistical significance, continuous analysis of the full ordinal scales showed significant improvement in both mRS and BI scores in the RNS60 1.0 mL/kg per hour treated group compared with the placebo group. Promising trends (as defined by P>0.05 and <0.15) were also observed for improved BI and EQ-5D-5L scores at day 90, with 72.2% of participants receiving RNS60 1.0 mL/kg per hour having a BI score of ≥95 (indicating functional independence) compared with 36.8% of participants who received placebo (P=0.13), and a mean difference of 0.2 for the EQ-5D-5L index score between RNS60 1.0 mL/kg per hour and placebo (P=0.07). An EQ-5D-5L index score difference of >0.1 is considered clinically meaningful for stroke patients.³²

RNS60 1.0 mL/kg per hour definite responders were participants who had lower disability and higher independence ratings after 90 days, as measured by mRS score of 0 to 2, BI score ≥95, and NIHSS score 0 to 1, all 3 functional outcome scales used in RESCUE. This supports the hypothesis that the participants who responded to the RNS60 1.0 mL/kg per hour treatment were functioning well because they showed improvements across 3 different scales designed to evaluate various activities of daily living. In addition, RNS60 1.0 mL/kg per hour reduced the time spent in the hospital and resulted in a higher percentage of treated participants being discharged to their home compared with those treated with a placebo.

Overall, the changes observed across all prespecified end points were consistent, showing trends for a beneficial effect of RNS60 1.0 mL/kg per hour treatment, which supports further development of RNS60 as a cytoprotective drug to reduce post-EVT infarct growth and improve functional outcomes in patients with AIS with LVO. Consistent but smaller effects were seen in the RNS60 0.5 mL/kg per hour group, which suggests a dose-dependent effect of RNS60. The main limitation of these data is that they are from a post hoc analysis of a small phase 2 trial that was not powered for its efficacy end points. Moreover, baseline imbalances in thrombolytic use and NIHSS may have partially contributed to the effects seen on day 90, although the imbalance was not large. To confirm the results, an appropriately powered study in participants randomized within 12 hours since LKW is in development, which will include thrombolytic use as one of the factors for randomization. Because of the relatively small number of study sites and participants, the RESCUE trial also had limited diversity. The higher number of study sites and participants in a follow-up study will also aim at enhancing geographic and participant diversity and thereby help to reduce the risk identified in prior studies that White male patients will be enrolled at a higher frequency, as they tend to be the patients who arrive at the hospital or stroke center earlier for treatment.³³

In summary, the RESCUE post hoc analyses demonstrated that RNS60 administered for 48 hours reduced infarct growth, increased the likelihood of nondisability, independent living, and improved quality-of-life while reducing the length of the hospital stay in patients with AIS with LVO undergoing EVT enrolled within 12 hours since LKW. Thereby, these analyses identified this group as the target population for a larger, appropriately powered trial to test this promising cytoprotective therapy.

ARTICLE INFORMATION

Presented in parts at the European Stroke Organization Conference, Helsinki, Finland, May 21–23, 2025; American Academy of Neurology, San Diego, CA, April 5–9, 2025; Society of NeuroInterventional Surgery Annual Meeting, Nashville, TN, July 14–18, 2025; and World Stroke Congress, Barcelona, Spain, October 22–24, 2025.

Author Contributions

Dr Ghosh wrote the manuscript. Dr Ghosh, Dr Favilla, Dr Kalmes, Dr Fisher, J. Sutherland, Dr Clark, J. Mock, Dr Liebeskind, L. Anderson, and Dr Nicodemus Johnson edited the manuscript. Drs McTaggart, Ghosh, and Dubow contributed to the study design. Dr Dubow, J. Sutherland, Dr McTaggart, Dr Chiu, Dr Clark, Dr Favilla, Dr Ansari, J. Mock, and Dr Liebeskind collected the data. Dr Dubow, Dr Liebeskind, L. Anderson, and J. Nicodemus Johnson analyzed the data. Dr Ghosh, Dr Dubow, J. Sutherland, Dr Liebeskind, and Dr Fisher approved the final manuscript. The authors were assisted in the preparation of this manuscript by professional medical writers from Core Content Network, compensated by the sponsor.

Disclosures

Dr Ghosh, J. Sutherland, Dr Kalmes, and J. Mock are employed by Revalesio. Dr Dubow has stock options in Revalesio. Dr Ansari reports consulting at the imaging core lab for Oculus Imaging, consulting at Imperative Care, and serving on the Data and Safety Monitoring Board for Rapid Medical, Perfuze, Microvention, and Medtronic. Dr Liebeskind reports consulting at imaging core labs for Cerenovus, Genentech, Medtronic, Rapid Medical, Revalesio, and Stryker. Dr Fisher reports consulting for Lumosa, Simcere USA, and Revalesio; and serving on the Data Safety Monitoring Boards for Moleac and the National Institute of Neurological Disorders and Stroke. The other authors report no conflicts.

Supplemental Material

Table S1. Secondary Efficacy Analysis Methods

Figure S1. Infarct Volume Correlates With 90-Day mRS

CONSORT Checklist

Supplementary Material

svi2-6-e002196-s001.docx ^{(175KB, docx)}

svi2-6-e002196-s002.docx ^{(32.4KB, docx)}

Funding Statement

The sponsor and funder of the study (Revalesio) manufactures the drug (RNS60) and has principal leadership for the study, including the final responsibility for the analysis of the data and decision to submit for publication.