Usefulness of the maintenance of wakefulness test in central disorders of hypersomnolence: a scoping review

Efficacy and Safety of Sodium Oxybate in Adults With Idiopathic Hypersomnia: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Idiopathic hypersomnia (IH) is a rare central disorder of hypersomnolence characterized by excessive daytime sleepiness, prolonged nighttime sleep, and sleep inertia. Low-sodium oxybate is the sole Food and Drug Administration-approved treatment for IH. Objective measures of nighttime sleep and daytime sleepiness are lacking with oxybates in IH. We aimed to evaluate efficacy and safety of sodium oxybate (SXB) in IH.

METHODS

This phase 3, double-blind, parallel-group, placebo-controlled trial was conducted at the National Reference Center for Hypersomnia in Montpellier-France. Eligible participants aged 18-60 years with IH with an Epworth Sleepiness Scale (ESS) score ≥14 were randomly assigned to receive SXB or placebo (1:1). After a 2-week screening without any drugs and without exposure to oxybate, patients started a 6-week individual twice-nightly up-titration scheme from 4.5 g to a maximum of 9 g. Treatment was administered at stable dose for 2 weeks, followed by a 2-week taper period. The primary endpoint was the between-group difference in ESS scores at week 8, identified by a covariance analysis, including baseline ESS scores. The same methodology was applied for secondary endpoints including Idiopathic Hypersomnia Severity Scale (IHSS) score and sleep latency on the Maintenance of Wakefulness Test (MWT). Safety was examined as a secondary endpoint.

RESULTS

Among the 48 patients screened, 45 were randomized (36 women, 29.0 ± 7.5 years, 22 assigned to SXB, 23 to placebo) and 40 (19 receiving SXB, 21 placebo) completed the study. In the intention-to-treat analysis, the mean ESS score was significantly reduced in the SXB group compared with placebo, after adjusting for the baseline score (least squared [LS] mean difference: -6.86, 95% CI [-9.73 to -4.00]), p < 0.0001). Significant differences between SXB and placebo groups at week 8 were observed for the IHSS score (LS mean difference: -11.61; 95% CI [-16.63 to -6.59], p < 0.0001) and MWT latency (14.75; 95% CI [9.98-19.52], p < 0.0001). Treatment-emergent adverse events (nausea, headache, and dizziness) were reported in 81.8% patients with SXB and 26.1% with placebo.

DISCUSSION

SXB resulted in a clinically meaningful improvement in adults with IH, reducing excessive sleepiness on ESS, improving wakefulness on MWT, and decreasing IH severity on IHSS after 8 weeks. The safety profile was consistent with previous reports on SXB.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov NCT03597555, EudraCT number 2017-004122-15.

CLASSIFICATION OF EVIDENCE

This article provides Class I evidence that sodium oxybate at a dose of 4.5-9 g per night compared with placebo reduces excessive sleepiness, improves wakefulness, and decreases disease severity with expected side effects in patients with idiopathic hypersomnia.

Oveporexton, an Oral Orexin Receptor 2-Selective Agonist, in Narcolepsy Type 1

BACKGROUND

Narcolepsy type 1 is a disorder of hypersomnolence caused by a loss of orexin neurons, which results in low orexin levels in the brain.

METHODS

In this phase 2, randomized, placebo-controlled trial, participants with narcolepsy type 1 received once- or twice-daily oveporexton (TAK-861), an oral orexin receptor 2-selective agonist, or placebo. The primary end point was the mean change from baseline to week 8 in average sleep latency (the time it takes to fall asleep) on the Maintenance of Wakefulness Test (MWT) (range, 0 to 40 minutes; normal, ≥20). Secondary end points included the change from baseline to week 8 in the Epworth Sleepiness Scale (ESS) total score (range, 0 to 24; normal, ≤10), the weekly cataplexy rate at week 8, and the occurrence of adverse events.

RESULTS

A total of 90 participants received oveporexton (0.5 mg twice daily, 23 participants; 2 mg twice daily, 21 participants; 2 mg followed by 5 mg daily, 23 participants; and 7 mg once daily, 23 participants), and 22 received placebo. The mean changes from baseline to week 8 in average sleep latency on the MWT were 12.5, 23.5, 25.4, 15.0, and -1.2 minutes, respectively (adjusted P≤0.001 for all comparisons vs. placebo). The mean changes in the ESS total score at week 8 were -8.9, -13.8, -12.8, -11.3, and -2.5, respectively (adjusted P≤0.004 for all comparisons vs. placebo). The weekly incidence of cataplexy at week 8 was 4.24, 3.14, 2.48, 5.89, and 8.76, respectively (adjusted P<0.05 for 2 mg twice daily and 2 mg followed by 5 mg daily vs. placebo). The most common adverse events associated with oveporexton were insomnia (in 48% of the participants; most cases resolved within 1 week), urinary urgency (in 33%), and urinary frequency (in 32%), without any hepatotoxic effects.

CONCLUSIONS

In this phase 2 trial involving participants with narcolepsy type 1, oveporexton significantly improved measures of wakefulness, sleepiness, and cataplexy over a period of 8 weeks. (Funded by Takeda Development Center Americas; TAK-861-2001 ClinicalTrials.gov number, NCT05687903.).

Transcutaneous auricular vagus nerve stimulation to treat narcolepsy type 1 (TARGET-NT1): A two-arm, randomised, sham-controlled trial

To assess exploratorily the safety and efficacy of transcutaneous auricular vagus nerve stimulation (tVNS) as an adjunctive therapy in improving symptoms in patients with narcolepsy type 1 (NT1). The TARGET-NT1 trial, a two-arm, double-blinded, sham-controlled trial was conducted from April 2022, to June 2024 ​at Xijing Hospital in Xi'an, China. Participants were randomised to receive tVNS treatment or sham tVNS (stVNS) treatment. Both interventions were performed for two 30-min periods per day with the same stimulation parameters but different stimulation points, for 12 weeks. The primary outcome was the change in mean sleep onset latency of maintenance of wakefulness test (MWT) from baseline to week 12. Secondary outcomes included changes in Narcolepsy Severity Scale (NSS), Epworth Sleepiness Scale (ESS), 14-item Hamilton Anxiety Rating Scale (HAMA-14), 17-item Hamilton Depression Rating Scale (HAMD-17). Among 60 randomised participants (32 men [53.3 ​%] and 28 [46.7 ​%]; mean [SD] age, 29.9 [9.9] years), 56 were included in the modified intention-to-treat (mITT) analysis. From baseline to week 12, the difference in mean change in mean sleep onset latency of MWT was 3.09 (95 ​% CI, 1.00, 5.88; P ​= ​0.0041) as compared with stVNS group. Significant improvements in NSS-EDS (-2.61 [95%CI, -4.07, -1.15; P ​= ​0.0006]), NSS-SP (-1.11 [95%CI, -1.83, -0.38; P ​= ​0.0030]), NSS-HH (-2.71 [95%CI, -3.36, -2.05; P ​< ​0.0001]), NSS- DNS (-0.52 [95%CI, -0.87, -0.17; P ​= ​0.0036]), ESS (-3.03 [95%CI, -4.30, -1.75; P ​< ​0.0001]) and HAMD-17 (-2.50 [95%CI, -4.30, -0.70; P ​= ​0.0069]) were observed in the tVNS group as compared with stVNS group. This exploratory study supported the efficacy and safety of tVNS in patients with NT1 and provided insights into the mechanisms underlying tVNS treatment for NT1. The findings highlight tVNS as a potential non-pharmacological adjunctive therapy for patients with NT1. This trial was registered with the Chinese Clinical Trial Registry, ChiCTR2400094550.

Novel biomarkers derived from the Maintenance of Wakefulness Test as predictors of sleepiness and response to treatment

The Maintenance of Wakefulness Test (MWT) is a widely accepted objective test used to evaluate daytime somnolence and is commonly used in clinical studies evaluating novel therapeutics for excessive daytime sleepiness. In the latter, sleep onset latency (SOL) is typically the sole MWT endpoint. Here, we explored microsleeps, sleep probability measures derived from automated sleep scoring, and quantitative electroencephalography (qEEG) features as additional MWT biomarkers of daytime sleepiness, using data from a phase 1B trial of the selective orexin receptor 2 agonist danavorexton (TAK-925) in people with narcolepsy type 1 (NT1) or type 2 (NT2). Danavorexton treatment reduced the rate and duration of microsleeps during the MWT in NT1 (days 1 and 7; p ≤ .005) and microsleep rate in NT2 (days 1 and 7; p < .0001). The use of an EEG-sleep-staging - derived measure to determine the probability of wakefulness for each minute revealed a novel metric to track changes in daytime sleepiness, which were consistent with the θ/α ratio, a known biomarker of drowsiness. The slopes of line-fits to both the log-transformed sleepiness score or log-transformed θ/α ratio correlated well to (inverse) MWT SOL for NT1 (R = 0.93 and R = 0.83, respectively) and NT2 (R = 0.97 and R = 0.84, respectively), suggesting that individuals with narcolepsy have increased sleepiness immediately after lights-off. These analyses demonstrate that novel EEG-based biomarkers can augment SOL as predictors of sleepiness and its response to treatment and provide a novel framework for the analysis of wake EEG in hypersomnia disorders.

Skin temperature as a predictor of on-the-road driving performance in people with central disorders of hypersomnolence

Excessive daytime sleepiness is the core symptom of central disorders of hypersomnolence (CDH) and can directly impair driving performance. Sleepiness is reflected in relative alterations in distal and proximal skin temperature. Therefore, we examined the predictive value of skin temperature on driving performance. Distal and proximal skin temperature and their gradient (DPG) were continuously measured in 44 participants with narcolepsy type 1, narcolepsy type 2 or idiopathic hypersomnia during a standardised 1-h driving test. Driving performance was defined as the standard deviation of lateral position (SDLP) per 5 km segment (equivalent to 3 min of driving). Distal and proximal skin temperature and DPG measurements were averaged over each segment and changes over segments were calculated. Mixed-effect model analyses showed a strong, quadratic association between proximal skin temperature and SDLP (p < 0.001) and a linear association between DPG and SDLP (p < 0.021). Proximal skin temperature changes over 3 to 15 min were predictive for SDLP. Moreover, SDLP increased over time (0.34 cm/segment, p < 0.001) and was higher in men than in women (3.50 cm, p = 0.012). We conclude that proximal skin temperature is a promising predictor for real-time assessment of driving performance in people with CDH.

Objective evaluation of excessive daytime sleepiness

Excessive daytime sleepiness (EDS) is multifactorial. It combines, among other things, an excessive propensity to fall asleep ("physiological sleepiness") and a continuous non-imperative sleepiness (or drowsiness/hypo-arousal) leading to difficulties remaining awake and maintaining sustained attention and vigilance over the long term ("manifest sleepiness"). There is no stand-alone biological measure of EDS. EDS measures can either capture the severity of physiological sleepiness, which corresponds to the propensity to fall asleep, or the severity of manifest sleepiness, which corresponds to behavioral consequences of sleepiness and reduced vigilance. Neuropsychological tests (The psychomotor vigilance task (PVT), Oxford Sleep Resistance Test (OSLeR), Sustained Attention to Response Task (SART)) explore manifest sleepiness through several sustained attention tests but the lack of normative values and standardized protocols make the results difficult to interpret and use in clinical practice. Neurophysiological tests explore the two main aspects of EDS, i.e. the propensity to fall asleep (Multiple sleep latency test, MSLT) and the capacity to remain awake (Maintenance of wakefulness test, MWT). The MSLT and the MWT are widely used in clinical practice. The MSLT is recognized as the "gold standard" test for measuring the severity of the propensity to fall asleep and it is a diagnostic criterion for narcolepsy. The MWT measures the ability to stay awake. The MWT is not a diagnostic test as it is recommended only to evaluate the evolution of EDS and efficacy of EDS treatment. Even if some efforts to standardize the protocols for administration of these tests have been ongoing, MSLT and MWT have numerous limitations: age effect, floor or ceiling effects, binding protocol, no normal or cutoff value (or determined in small samples), and no or low test-retest values in some pathologies. Moreover, the recommended electrophysiological set-up and the determination of sleep onset using the 30‑sec epochs scoring rule show some limitations. New, more precise neurophysiological techniques should aim to detect very brief periods of physiological sleepiness and, in the future, the brain local phenomenon of sleepiness likely to underpin drowsiness, which could be called "physiological drowsiness".