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Study on the Effects of Pitolisant Hydrochloride for Patients with Prader-Willi Syndrome

Fast replyInvestigationalNo placebo
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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 Prader-Willi syndrome, a genetic condition that affects many parts of the body. The study will evaluate the effects of a medication called pitolisant hydrochloride, which is also known by the code name HBS-101 and is marketed under the name WAKIX. The purpose of the study is to assess how this medication impacts the severity of excessive daytime sleepiness in patients with Prader-Willi syndrome.

The study will be conducted in two main phases. Initially, participants will be randomly assigned to receive either the medication or a placebo, which looks like the medication but does not contain the active ingredient. This phase is double-blind, meaning neither the participants nor the researchers will know who is receiving the actual medication. After this phase, all participants will have the opportunity to receive the medication in an open-label extension, where everyone knows they are receiving the active treatment. The study will last for several weeks, with regular check-ins to monitor the participants' health and any changes in their symptoms.

Throughout the study, the effects of pitolisant hydrochloride on various symptoms of Prader-Willi syndrome will be closely monitored. This includes not only the primary focus on excessive daytime sleepiness but also other related symptoms such as irritable and disruptive behaviors. The safety of the medication will also be assessed by tracking any side effects experienced by participants. The study aims to provide valuable information on the potential benefits and safety of using pitolisant hydrochloride for managing symptoms in individuals with Prader-Willi syndrome.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Double-blind treatment period

    During this phase, the patient will receive either the study medication, pitolisant hydrochloride, or a placebo. The medication is administered in the form of a tablet taken orally.

    The dosage of the medication will be determined by the study team and will be adjusted as necessary based on the patient's response and any side effects experienced.

    This phase lasts for 77 days, during which the patient will be monitored for changes in the severity of excessive daytime sleepiness (EDS) and other symptoms associated with Prader-Willi syndrome.

  2. Step 2

    Open-label extension

    After completing the double-blind treatment period, the patient will enter the open-label extension phase.

    In this phase, all patients will receive pitolisant hydrochloride regardless of their previous group assignment. The medication will continue to be administered orally in tablet form.

    The duration of this phase will be determined by the study team, and the patient's response to the medication will be closely monitored.

  3. Step 3

    Monitoring and assessments

    Throughout the study, the patient will undergo regular assessments to evaluate the effectiveness and safety of the treatment.

    These assessments will include measuring changes in the severity of EDS, irritable and disruptive behaviors, and other symptoms using various standardized questionnaires and scales.

    The patient's health and any side effects experienced will be closely monitored to ensure safety and well-being.

Who can join the trial?

13 criteria

  • Patients must be male or female and at least 6 years old at the time of screening.
  • Patients with a history of seizures must have a stable seizure history, meaning the frequency and severity of seizures have not changed, for at least 6 months before screening.
  • Female patients who can become pregnant must have a negative pregnancy test at screening and agree to use a reliable nonhormonal birth control method during the study and for 21 days after the last dose of the study drug. If using hormonal birth control, they must also use a nonhormonal method during the study and for 21 days after stopping the study drug. Male patients who can father children must agree to use a barrier method of birth control during the study and for 21 days after the last dose of the study drug.
  • Patients must have a consistent parent or caregiver, preferably the same person throughout the study, who is willing and able to complete the required study assessments.
  • The patient, along with their parent(s), caregiver(s), or legal guardian(s), must be able to understand and follow the study requirements and take the oral study drug as instructed.
  • The patient or their parent(s), caregiver(s), or legal guardian(s) must be able to provide written consent to participate in the study. If applicable, the patient must also provide written agreement to participate.
  • The patient must have a confirmed diagnosis of Prader-Willi syndrome (PWS) through genetic testing or medical records. If not confirmed, genetic testing will be provided by the study sponsor.
  • The patient must meet criteria for excessive daytime sleepiness (EDS) based on specific questionnaires.
  • The patient must get an appropriate amount of sleep each night based on their age.
  • If the patient is taking any long-term medications or supplements that are not prohibited, they must be on a stable dose for at least 30 days before screening and agree to continue the stable dose during the study or stop taking them for a certain period before screening.
  • If the patient is taking hormone treatments like growth hormone, testosterone, or estrogen, they must be on a stable dose for 30 days before screening and during the study, with a small variation allowed.
  • If the patient is using cannabidiol (CBD) or tetrahydrocannabinol (THC), they must be on a stable dose for 30 days before screening and agree to continue the stable dose during the study or stop using them for a certain period before screening.
  • If the patient is taking a strong CYP2D6 inhibitor, a type of medication that affects how the body processes drugs, they must be on a stable dose for at least 30 days before screening and during the study or stop taking it for a certain period before screening.

Who cannot join the trial?

5 criteria

  • Patients who do not have Prader-Willi syndrome cannot participate. Prader-Willi syndrome is a genetic condition that affects many parts of the body.
  • Patients who are not within the specified age ranges cannot participate. The age ranges include children, adolescents, and adults.
  • Patients who are not part of the specified clinical trial groups cannot participate. Clinical trial groups refer to specific categories of patients that the study is focusing on.
  • Both male and female patients are eligible, so exclusion is not based on gender.
  • Patients who are not considered part of a vulnerable population cannot participate. Vulnerable populations include groups that may need special protection or consideration in research.
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Investigated drugs

Pitolisant is a medication being studied for its effectiveness in reducing excessive daytime sleepiness (EDS) in patients with Prader-Willi Syndrome (PWS). It works by increasing the levels of certain chemicals in the brain that help promote wakefulness and alertness. This study aims to determine how well pitolisant can improve the symptoms of EDS in individuals with PWS.

What is already known about the treatment

Pitolisant – Pitolisant is administered orally in tablet form. It is currently being studied in a Phase 3 clinical trial for its effectiveness and safety in treating Prader-Willi syndrome, specifically targeting excessive daytime sleepiness (EDS) associated with the condition. The medication works by increasing the release of histamine in the brain, which helps to promote wakefulness and alertness. Pitolisant is classified as a histamine H3 receptor antagonist/inverse agonist, which means it blocks the action of histamine at the H3 receptor, leading to increased histamine activity in the central nervous system.

Investigated diseases

Prader-Willi syndrome – This is a rare genetic disorder that affects many parts of the body. It is characterized by a constant sense of hunger, leading to overeating and obesity. Individuals with this syndrome often have low muscle tone, short stature, and cognitive disabilities. Behavioral problems such as temper outbursts and stubbornness are common. Sleep disturbances, including excessive daytime sleepiness, are also frequently observed. The condition is caused by a loss of function of specific genes on chromosome 15.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-508307-21-00Protocol codeHBS-101-CL-312Estimated enrolment134 patientsSponsorHarmony Biosciences LLC

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