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Study on TAK-861 for Treating Narcolepsy with Cataplexy in Patients

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the condition known as narcolepsy with cataplexy, which is also referred to as narcolepsy type 1. Narcolepsy is a sleep disorder that causes excessive daytime sleepiness and sudden loss of muscle control, known as cataplexy. The study will evaluate a new treatment called TAK-861, which is taken in the form of a tablet. The purpose of the study is to assess how effective and safe TAK-861 is in treating narcolepsy with cataplexy.

Participants in the study will be randomly assigned to receive either the TAK-861 tablet or a placebo, which looks like the TAK-861 tablet but does not contain the active medication. The study will last for a period of 12 weeks, during which participants will take the medication daily. Throughout the study, participants will have regular check-ups to monitor their health and the effects of the treatment. The main focus will be on changes in daytime sleepiness, which will be measured using a tool called the Epworth Sleepiness Scale.

In addition to monitoring sleepiness, the study will also look at other aspects of narcolepsy, such as the frequency of cataplexy episodes and overall quality of life. Participants will be asked to complete various assessments and questionnaires to provide a comprehensive understanding of how TAK-861 affects their condition. The study aims to gather valuable information that could lead to improved treatment options for people living with narcolepsy with cataplexy.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, the participant will be randomly assigned to receive either the medication TAK-861 or a placebo. The placebo is a tablet that looks like the medication but does not contain the active substance.

    The study is designed to be double-blind, meaning neither the participant nor the researchers will know who is receiving the actual medication or the placebo.

  2. Step 2

    Medication administration

    The participant will take the assigned tablet orally. The specific dosage and frequency will be determined by the study protocol and communicated to the participant at the start of the trial.

    The duration of the medication administration phase is 12 weeks.

  3. Step 3

    Monitoring and assessments

    Throughout the 12-week period, the participant's condition will be monitored regularly. This includes assessments of excessive daytime sleepiness using the Epworth Sleepiness Scale (ESS).

    Additional assessments may include measuring sleep latency, cataplexy episodes, and other cognitive and physical evaluations.

  4. Step 4

    End of treatment evaluation

    At the end of the 12-week treatment period, the participant will undergo a final evaluation to assess the effects of the medication or placebo.

    This evaluation will include a review of the participant's ESS score, sleep latency, and any other relevant health indicators.

  5. Step 5

    Follow-up period

    After the treatment phase, there will be a follow-up period to monitor any ongoing effects or side effects of the medication.

    The participant will be asked to report any adverse events or changes in their condition during this time.

Who can join the trial?

6 criteria

  • Participants must be **male or female** and aged between **18 to 70 years**.
  • Participants should have a **body mass index (BMI)** between **18 to 40 kg/m²**. BMI is a measure of body fat based on height and weight.
  • Participants must have a diagnosis of **Narcolepsy Type 1 (NT1)** according to specific medical guidelines.
  • Participants should experience **4 or more episodes of cataplexy** per week. Cataplexy is a sudden loss of muscle strength, often triggered by strong emotions.
  • Participants must test positive for a specific **human leukocyte antigen (HLA)** type, or have a low level of a brain chemical called **hypocretin-1** in their spinal fluid. These are specific medical tests related to narcolepsy.
  • Participants must be considered **healthy enough** to join the study based on various health checks, including blood tests, medical history, physical exams, heart tests (ECG), and vital signs like blood pressure and heart rate.
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Investigated drugs

TAK-861 is a medication being studied for its potential to treat narcolepsy with cataplexy, also known as Narcolepsy Type 1. This condition is characterized by excessive daytime sleepiness (EDS) and sudden muscle weakness triggered by strong emotions. The trial aims to evaluate how well TAK-861 can reduce daytime sleepiness, as measured by a specific scale called the Epworth Sleepiness Scale (ESS). The study is designed to be double-blind, meaning neither the participants nor the researchers know who is receiving the medication or a placebo, to ensure unbiased results.

What is already known about the treatment

TAK-861 – TAK-861 is an investigational medication currently being studied for its potential to treat narcolepsy with cataplexy, also known as Narcolepsy Type 1. It is administered orally in the form of tablets. The medication is in the clinical trial phase, specifically in a randomized, double-blind, placebo-controlled study, to evaluate its efficacy and safety. TAK-861 is designed to reduce excessive daytime sleepiness, a common symptom of narcolepsy, by targeting specific receptors in the brain that regulate wakefulness. It belongs to the pharmacological class of central nervous system stimulants.

Investigated diseases

Narcolepsy with Cataplexy (Narcolepsy Type 1) – This is a chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden attacks of sleep. People with this condition often experience cataplexy, which is a sudden loss of muscle tone triggered by strong emotions. The disorder disrupts the normal sleep-wake cycle, leading to fragmented nighttime sleep and excessive daytime sleepiness. Individuals may also experience sleep paralysis and hallucinations as they fall asleep or wake up. The progression of symptoms can vary, but they often begin in childhood or adolescence and persist throughout life. The exact cause is not fully understood, but it is believed to involve a deficiency of the brain chemical hypocretin.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-508465-32-00Protocol codeTAK-861-3001Estimated enrolment152 patientsSponsorTakeda Development Center Americas Inc.

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