Effect of nelonemdaz for patients with out-of-hospital cardiac arrest: the AWAKE phase II randomised clinical trial

Abstract Background Hypoxic brain injury is a major hurdle that limits the survival of out-of-hospital cardiac arrest (OHCA). Nelonemdaz is a dual-target neuroprotectant, serving as a moderate NR2B-selective N-methyl-D-aspartate (NMDA) receptor antagonist while also exhibiting potent free radical scavenger properties. This dual neuroprotective action of nelonemdaz has the potential to reduce hypoxic brain injury in OHCA. We investigated the efficacy and safety of nelonemdaz for patients with OHCA. Methods AWAKE trial was a double-blind, placebo-controlled, randomised, multicentre phase II trial at 5 sites in South Korea. OHCA patients undergoing targeted temperature management were randomly assigned to high-dose (5250 mg), low-dose (3250 mg), and placebo groups at a 1:1:1 ratio. The primary outcome was the blood level of neuron-specific enolase (NSE) after 4th administration of drug. Secondary outcomes comprised blood biomarkers including neuron specific enolase (NSE) and S100beta, brain magnetic resonance imaging (MRI), and Cerebral Performance Category (CPC) and Modified Rankin Scale (mRS) up to day 90. Safety is assessed by serious adverse event. Findings: A total of 105 patients were enrolled between November 18, 2018 to February 23, 2023. Patients with a median age of 61 years and 82% male were assigned to the high-dose (N=37), low-dose (N=35), and placebo (N=33) groups. Primary outcome was evaluated in 93 patients. There was no difference of neuron specific enolase (NSE, ng/mL), which served as the primary endpoint, between high-dose (median and interquartile range; 23·7, 15·0–69·9) and placebo (17·5, 13·6–113·0) groups and also between low-dose (26·6, 16·2–83·4) versus placebo groups (all p>0·05). Among secondary outcomes, fractional anisotropy of brain MRI was significantly higher in high-dose group compared to placebo group (0·465, 0·449–0·485 versus 0·441, 0·431–0·464; p=0·028), and was not different between low-dose (0·462, 0·439–0·480) and placebo groups (p>0·05). At day 90, the common odds ratio (95% confidence interval) indicating a favourable shift in the modified Rankin Scale was 1·25 (0·48–3·24) and 1·22 (0·47–3·20) in the high-dose and low-dose groups respectively, compared to placebo group (all p>0·05). No serious adverse events were reported. Interpretation: Nelonemdaz did not reduced blood NSE level of OHCA patients. However, patients treated with high-dose nelonemdaz showed better fractional anisotropy that suggests reduced cerebral white matter damage. Patients treated with nelonemdaz also showed a favourable tendency of neurological recovery at day 90 without significant adverse effects. These results justify the initiation of a large-scale phase III trial.Neurological function up to day 90