Trial Outcomes & Findings for A Study of TAK-861 in People With Narcolepsy Type 1 (NCT NCT06505031)

Participants took part in the study at various investigative sites globally from 08 October 2024 to 04 June 2025.

A total of 105 participants were randomized in a 1:2 ratio to receive either placebo or oveporexton (TAK-861).

A Study of TAK-861 in People With Narcolepsy Type 1

The MWT evaluates a person's ability to remain awake under soporific conditions for a defined period of time. Because there is no biological measure of wakefulness, wakefulness is measured indirectly by the inability or delayed tendency to fall asleep. This tendency to fall asleep is measured via electroencephalography-derived sleep latency in the MWT. The MWT consists of four 40-minute sessions (trials) done 2 hours apart. Sleep latency in each session was recorded. Participants were required to stay awake in between the four sessions. A positive change from baseline indicates an improvement. The linear MMRM was used for analysis.

The ESS provides individuals with 8 different situations of daily life and asks them how likely they are to fall asleep in those situations (scored 0 to 3) and to try to imagine their likelihood of dozing even if they have not actually been in the identical situation; the scores are summed to give an overall score of 0 to 24. Higher scores indicate stronger subjective daytime sleepiness. A negative change from baseline indicates an improvement. The linear mixed effects model for repeated measures (MMRM) was used for analysis.

Participants completed a daily participant-reported cataplexy diary to record self-reported episodes of cataplexy attacks. WCR = (total number of cataplexy attacks over a number of non-missing diary days for a given period/number of non-missing diary days in that period) \* 7. The generalized estimating equations (GEE) model was used for analysis. Reported here is the estimated mean of incidence rate with a 95 percent (%) confidence interval (CI).

The PVT is a simple reaction performance task that aims to measure sustained attention. The mean number of lapses (delayed responses to a visual cue from intraday sessions) from the two 10-minute intraday sessions was used as a measure of objective sustained attention. A negative change from baseline indicates an improvement. A constrained Longitudinal Data Analysis (cLDA) model was used to analyze the mean number of lapses and to estimate change from baseline at each visit.

The PGI-C is a participant self-rated scale to assess change in daytime sleepiness and overall narcolepsy symptoms. The PGI-C includes 7 items being scored from 1 (best outcome) to 7 (worst outcome) with 4 being no change. Responders were the participants reporting "1=very much improved" or "2=much improved" on PGI-C. Responder rate (proportion of participants who were responders) was estimated using a GEE model.

The NSS-CT is a 15-item self-administered questionnaire that assesses the severity and consequences of the 5 major narcolepsy symptoms such as daytime sleepiness, cataplexy, hallucinations, sleep paralysis, and disturbed nighttime sleep (DNS) with a total score range of 0 to 57 (sum of 6 items that assess symptoms severity are rated using a six-point Likert scale \[0-5\] and 9 items that describe the symptom effect on daily life are rated using a four-point Likert scale \[0-3\]). Higher total scores mean a worse outcome. A negative change from baseline indicates an improvement. The linear MMRM was used for analysis.

The FINI measures the functional impacts of narcolepsy across 6 domains Tiredness (items 1-7), Cognitive Functioning (items 8-12), Cataplexy (items 13-17), Social Activities (items 18-21), Everyday Activities (items 22-25), and Everyday Responsibilities (items 26-28). Each item asks about the impact that narcolepsy has had on their daily functioning during the past 7 days, and is scored from 0 to 4, where 0 indicates the best health and 4 the worst. An average score is calculated for each domain and then standardized to a 0-100 scale, where 0 indicates the best health and 100 the worst health. Standardized score = average score/4 × 100. A negative change from baseline indicates and improvement. The linear MMRM was used for analysis.

The SF-36 is a 36-item, participant-reported survey of participant health that assesses the quality of life and includes both physical and mental components. It consists of 8 scaled scores (vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning, mental health), which contribute variably to the physical and mental component summary scores. The component summary is scored based on a normal value of 50 based on US population average, with a normative range considered from 45-55. The lower the score the more disability. A positive change from baseline indicates an improvement, and a change greater than 3 points is considered minimally clinically meaningful. The linear MMRM was used for analysis.

An adverse event (AE) is any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product. A TEAE is defined as any event emerging or manifesting at or after the initiation of treatment with a study intervention or medicinal product or any existing event that worsens in either intensity or frequency following exposure to the study intervention or medicinal product.