For my graduate studies class “Neurodegeneration and Neuroprotection in Stroke”, I reviewed the results of the ESCAPE-NA1 clinical trial, which investigated whether Nerinetide, a potential neuroprotective agent, could improve outcomes for patients with ischemic stroke [1]. This trial was published in The Lancet in 2020 and targeted the neurotoxic nitric oxide (NO) signaling as a potential therapeutic strategy for ischemic stroke.

According to the Centers for Disease Control and Prevention, stroke is one of the leading causes of death and a major contributor to long-term disability in the United States [2]. Despite the significant public health burden of stroke, there are very few therapeutic options available. Currently, the fibrinolytic agent, tissue plasminogen activator (tPA or Alteplase), is the only acute pharmacological intervention in ischemic stroke that is approved by the U.S. Food and Drug Administration. Yet, due to numerous contraindications and a rather narrow therapeutic window, tPA is used in a minority of stroke patients. This emphasizes the need to develop new therapeutic approaches for ischemic stroke.

The ESCAPE-NA1 clinical trial tested the peptide Nerinetide as a potential neuroprotective agent [1]. The therapeutic effects of Nerinetide involve disruption of the functional interaction between NMDA receptors and the post-synaptic density protein 95 (PSD-95) [3]. Such disruption is thought to be beneficial because it reduces pathological activity of neuronal nitrogen oxide synthase (nNOS) [4]. Extensive preclinical work found that, in cerebral ischemia, elevated levels of extracellular glutamate cause prolonged activation of NMDA receptors and lead to intracellular Ca2+ overload [5]. In turn, intracellular Ca2+ activates nNOS, which is tightly anchored to the NMDA receptors using PSD-95 as a scaffold [6]. The premise was that preventing NMDAR/PSD-95 interaction would displace nNOS from the sites of Ca2+ entrance and reduce NO production. In rodents and gyrencephalic nonhuman primates, Nerinetide treatment protected the brain against experimental stroke [7-10].

ESCAPE-NA1 included 1105 ischemic stroke patients at numerous medical centers [1]. All patients included in the study underwent an attempted endovascular thrombectomy (EVT) and received Alteplase treatment when indicated. Patients were randomized to groups either receiving single dose Nerinetide (2.6mg/kg) or placebo. The primary measure of efficacy was a favorable outcome 90 days post-stroke, defined as a Modified Rankin Scale score (mRS) between 0-2, with secondary measures including mortality and changes in the National Institutes of Health (NIH) Stroke Scale score.

Overall, this trial revealed no significant improvements with Nerinetide treatment in the primary or secondary outcomes. A mRS of 0-2 at 90 days post-stroke was achieved by 61.4% of patients in the Nerinetide group and 59.2% of patients in the placebo group. However, when patients were separated into subgroups that either received or did not receive Alteplase, the Nerinetide-treated patients who did not receive Alteplase had significantly improved outcomes. In this subgroup, 59.3% of those receiving Nerinetide achieved an mRS score of 0–2 as compared to the 49.8% receiving placebo. Additionally, the Nerinetide subgroup without Alteplase had decreased infarction volumes as compared to placebo and exhibited a 7.5% reduction in mortality risk at 90 days post-stroke.

The differential effect of Nerinetide in the subgroups either receiving or not receiving Alteplase, suggested a potential drug-drug interaction between Nerinetide and Alteplase with loss of therapeutic efficacy of the Nerinetide treatment. The authors hypothesized that Nerinetide is proteolytically cleaved by plasmin, the product of plasminogen-to-plasmin conversion by Alteplase. This idea was supported by the significant decrease in plasma concentrations of Nerinetide in patients who received Alteplase. Potential solutions could include titrating the dose of Nerinetide to compensate for the presence of Alteplase, development of a drug that is impervious to cleavage by plasmin, or optimizing the timing of administration to prevent a drug-drug interaction.

    Due to the neuroprotective effect of Nerinetide in the subgroup of patients that did not receive Alteplase, the subsequent phase 3 clinical trial, ESCAPE-NEXT, was initiated. The goal of this trial was to investigate the effect of Nerinetide in patients who are not eligible for treatment with Alteplase. Based on the analysis of ESCAPE-NA1, 850 patients were enrolled and randomized into groups receiving either Nerinetide or placebo [11]. The trial was completed on August 31, 2023. The results of ESCAPE-NEXT are yet to be published, but they were presented in a preliminary form at the 15th World Stroke Congress (WSC) 2023. Based on what I have learned from commentary in the Stroke Alert Podcast hosted by the American Heart Association [12], in ESCAPE-NEXT, Nerinetide was not advantageous as compared to placebo. This is very unfortunate because our hopes for new therapeutic intervention have been placed on hold yet again.

    In addition to ESCAPE-NA1 and ESCAPE-NEXT, the smaller exploratory trial, FRONTIER, was conducted in Canada to test the effect of Nerinetide in the early pre-hospital setting in patients presenting with stroke symptoms [13]. In this study, 532 people were enrolled and randomized into Nerinetide and placebo groups. Paramedics in the field administered the treatment within 3 hours of symptom onset and ultimately 321 patients were subsequently diagnosed with ischemic stroke. This study is yet to be published.  However, its results were presented at the 15th World Stroke Congress (WSC) 2023 and discussed in the  Stroke Alert Podcase hosted by the American Heart Association [12]. It appears that Nerinetide treatment produced a favorable shift in the 90-day mRS. We enthusiastically await a full report of these trials and potential next steps.

References: 1) Hill, M. D., Goyal, M., Menon, B. K., Nogueira, R. G., McTaggart, R. A., Demchuk, A. M., Poppe, A. Y., Buck, B. H., Field, T. S., Dowlatshahi, D., van Adel, B. A., Swartz, R. H., Shah, R. A., Sauvageau, E., Zerna, C., Ospel, J. M., Joshi, M., Almekhlafi, M. A., Ryckborst, K. J., Lowerison, M. W., … ESCAPE-NA1 Investigators (2020). Efficacy and safety of nerinetide for the treatment of acute ischaemic stroke (ESCAPE-NA1): a multicentre, double-blind, randomised controlled trial. Lancet (London, England), 395(10227), 878–887. 2) Centers for Disease Control and Prevention, Stroke Facts. https://www.cdc.gov/stroke/data-research/facts-stats/index.html. (accessed on 05/17/2024). 3) Cui, H., Hayashi, A., Sun, H. S., Belmares, M. P., Cobey, C., Phan, T., Schweizer, J., Salter, M. W., Wang, Y. T., Tasker, R. A., Garman, D., Rabinowitz, J., Lu, P. S., & Tymianski, M. (2007). PDZ protein interactions underlying NMDA receptor-mediated excitotoxicity and neuroprotection by PSD-95 inhibitors. The Journal of neuroscience : the official journal of the Society for Neuroscience, 27(37), 9901–9915. 4) Girouard, H., Wang, G., Gallo, E. F., Anrather, J., Zhou, P., Pickel, V. M., & Iadecola, C. (2009). NMDA receptor activation increases free radical production through nitric oxide and NOX2. The Journal of neuroscience : the official journal of the Society for Neuroscience, 29(8), 2545–2552. 5) Lai, T. W., Zhang, S., & Wang, Y. T. (2014). Excitotoxicity and stroke: identifying novel targets for neuroprotection. Progress in neurobiology, 115, 157–188. 6) Cao, J., Viholainen, J. I., Dart, C., Warwick, H. K., Leyland, M. L., & Courtney, M. J. (2005). The PSD95-nNOS interface: a target for inhibition of excitotoxic p38 stress-activated protein kinase activation and cell death. The Journal of cell biology, 168(1), 117–126. 7) Sun, H. S., Doucette, T. A., Liu, Y., Fang, Y., Teves, L., Aarts, M., Ryan, C. L., Bernard, P. B., Lau, A., Forder, J. P., Salter, M. W., Wang, Y. T., Tasker, R. A., & Tymianski, M. (2008). Effectiveness of PSD95 inhibitors in permanent and transient focal ischemia in the rat. Stroke, 39(9), 2544–2553. 8) Teves, L. M., Cui, H., & Tymianski, M. (2016). Efficacy of the PSD95 inhibitor Tat-NR2B9c in mice requires dose translation between species. Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism, 36(3), 555–561. 9) Aarts, M., Liu, Y., Liu, L., Besshoh, S., Arundine, M., Gurd, J. W., Wang, Y. T., Salter, M. W., & Tymianski, M. (2002). Treatment of ischemic brain damage by perturbing NMDA receptor- PSD-95 protein interactions. Science (New York, N.Y.), 298(5594), 846–850. 10) Cook, D. J., Teves, L., & Tymianski, M. (2012). Treatment of stroke with a PSD-95 inhibitor in the gyrencephalic primate brain. Nature, 483(7388), 213–217. 11) Efficacy and Safety of Nerinetide in Participants With Acute Ischemic Stroke Undergoing Endovascular Thrombectomy Excluding Thrombolysis (ESCAPE-NEXT). ClinicalTrials.gov. Registry name identifier: NCT04462536. Last updated September 11, 2023 12) Broadcast of Stroke Alert December 2023. https://www.ahajournals.org/do/10.1161/podcast.-20231206.234364/full/ (accessed on 05/17/2024) 13) Field Randomization of Nerinetide (NA-1) Therapy in Early Responders (FRONTIER). ClinicalTrials.gov. Registry name identifier: NCT02315443. Last updated May, 12, 2023.