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Study on the Long-term Safety of TAK-861 for Patients with Narcolepsy Type 1

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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 a 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 is evaluating a treatment called TAK-861, which is taken in tablet form. The purpose of the study is to assess the long-term safety and tolerability of this medication in individuals with this condition.

Participants in the study will take TAK-861 over a period of time to see how well they tolerate the medication and to monitor any side effects that may occur. The study aims to ensure that the medication is safe for long-term use. Participants will be monitored for any treatment-emergent adverse events, which are any unwanted effects that occur after starting the medication.

The study will also look at changes in sleep patterns and symptoms from the beginning of the study to the end. This includes measuring how long participants can stay awake during the day and tracking any changes in their cataplexy symptoms using a diary. The study is expected to continue until early 2028, providing valuable information on the long-term use of TAK-861 for managing Narcolepsy with Cataplexy.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Participation begins after completing a previous controlled study with TAK-861.

    Enrollment is contingent upon the absence of any clinical objections from the investigator.

  2. Step 2

    Medication administration

    The medication TAK-861 is administered in the form of a tablet.

    The route of administration is oral.

  3. Step 3

    Monitoring and evaluation

    The primary focus is on the occurrence of any treatment-emergent adverse events.

    Secondary evaluations include changes from baseline in sleep latency, total score on the Epworth Sleepiness Scale (ESS), and cataplexy occurrences as recorded in a diary.

  4. Step 4

    Duration of the study

    The study is designed to continue until February 28, 2028.

    The long-term goal is to assess the safety and tolerability of TAK-861 over an extended period.

Who can join the trial?

6 criteria

  • The participant must have a diagnosis of Narcolepsy with Cataplexy, also known as Narcolepsy Type 1. This is a sleep disorder that includes sudden muscle weakness.
  • The participant must have completed a previous controlled study with the medication TAK-861. This means they have already taken part in a study where the effects of the medication were closely monitored.
  • The study doctor must have no medical concerns about the participant joining this new study.
  • Participants can be of any gender, meaning both males and females are eligible.
  • The study is open to certain age groups, specifically those that fall into categories 3 and 4, which typically include children and adults.
  • The study does not include vulnerable populations, which generally refers to groups that might need special protection or care.
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Investigated drugs

TAK-861 is a medication being studied for its safety and tolerability in people with certain sleep disorders known as central hypersomnia conditions. The trial aims to understand how well patients can tolerate this medication over a long period and to ensure it is safe for use in managing these sleep conditions.

What is already known about the treatment

TAK-861 – TAK-861 is an investigational medication currently being studied for its safety and tolerability in individuals with narcolepsy with cataplexy, also known as Narcolepsy Type 1. It is administered orally in the form of tablets. The medication is still in the clinical trial phase, and its effectiveness and safety are being evaluated in long-term studies. TAK-861 is believed to work by modulating certain neurotransmitters in the brain, which may help regulate sleep-wake cycles and reduce symptoms of excessive daytime sleepiness and cataplexy. It falls under the pharmacological classification of central nervous system agents.

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 such as laughter or surprise. 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 condition is believed to be related to a deficiency of a brain chemical called hypocretin, which helps regulate wakefulness. Symptoms typically begin in childhood or adolescence and can significantly impact daily activities and quality of life.
Trial detailsLast updated 4 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2023-508462-15-00Protocol codeTAK-861-2003Estimated enrolment462 patientsSponsorTakeda Development Center Americas Inc.

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