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Study on Long-Term Safety and Effects of PTC518 for Patients with Huntington's Disease

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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 Huntington's Disease, a genetic disorder that causes the progressive breakdown of nerve cells in the brain. The study is testing a treatment called PTC518, which is taken as a tablet. The purpose of the study is to evaluate the long-term safety and effectiveness of PTC518 in people with Huntington's Disease. The study will look at how the treatment affects levels of a protein called total huntingtin (tHTT) in the blood, which is associated with the disease.

Participants in the study will be randomly assigned to receive either the PTC518 tablet or a placebo, which looks like the treatment but does not contain the active substance. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual treatment or the placebo. This helps ensure that the results are not influenced by expectations about the treatment. The study will last for up to 24 months, during which participants will take the tablets and have regular check-ups to monitor their health and the effects of the treatment.

Throughout the study, various assessments will be conducted to monitor the safety of PTC518 and its impact on the disease. These assessments will include checking for any side effects, changes in vital signs, and physical examinations. Additionally, the study will measure changes in brain structure using a method called vMRI and evaluate specific protein levels in the blood and cerebrospinal fluid. The goal is to gather comprehensive data on how PTC518 affects the progression of Huntington's Disease over time.

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 must have completed the treatment period in a previous study, identified as PTC518-CNS-002-HD.

    The participant must be ambulatory, aged 25 years or older, and willing to provide informed consent.

  2. Step 2

    Medication administration

    The participant will receive a medication called PTC518, which is administered in tablet form for oral use.

    The dosage and frequency of administration will be determined by the study protocol.

  3. Step 3

    Safety and efficacy evaluation

    The study aims to evaluate the long-term safety of PTC518 in participants with Huntington's disease.

    The efficacy will be assessed by measuring the reduction in blood total huntingtin (tHTT) levels.

  4. Step 4

    Monitoring and assessments

    Participants will undergo regular monitoring, including assessments of vital signs, laboratory tests, and physical examinations.

    The study will also evaluate changes in caudate volume and cUHDRS scores over time.

  5. Step 5

    Completion of study

    The study is estimated to end on June 29, 2027.

    Participants will be required to follow specific guidelines regarding contraception and sperm donation for a period after stopping the study medication.

Who can join the trial?

5 criteria

  • The participant must be a male or female who can walk on their own and is aged 25 years or older.
  • The participant must have completed the Treatment Period in a specific study called PTC518-CNS-002-HD.
  • The participant must be willing and able to give their agreement to join the study and follow all the study rules.
  • Women who can have children must agree to use very effective birth control methods while taking the study medication and for 6 months after stopping it.
  • Men who are sexually active and can have children must use a condom during sex while taking the study medication and for 6 months after stopping it. They should not father a child or donate sperm during this time. Even men who have had a vasectomy must use a condom to prevent the drug from being passed through their semen.

Who cannot join the trial?

8 criteria

  • Individuals who do not have a confirmed diagnosis of Huntington's Disease cannot participate. This is a genetic disorder that affects the brain.
  • Participants must be within a specific age range, typically adults, to be eligible.
  • Both males and females can participate, but certain health conditions may exclude individuals.
  • People who are considered part of a vulnerable population may be excluded. This term refers to groups who might be at higher risk of harm or exploitation, such as children, pregnant women, or those with certain disabilities.
  • Individuals with other serious health conditions that could interfere with the study may not be eligible.
  • Participants must not be taking medications that could affect the study results.
  • Those who have participated in another clinical trial recently may be excluded to avoid interference with the study results.
  • Individuals who cannot comply with the study procedures or follow-up visits may not be eligible.
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Investigated drugs

PTC518 is a medication being studied for its potential to help people with Huntington's disease. The trial aims to see if PTC518 is safe to use over a long period and to understand how well it works by checking if it can lower the levels of a protein called huntingtin in the blood. This protein is linked to the symptoms of Huntington's disease, and reducing it might help manage the condition.

What is already known about the treatment

PTC518 – PTC518 is administered orally and is currently being studied in clinical trials for its long-term safety and effectiveness in treating Huntington's Disease. It is in the experimental phase, with ongoing research to understand its potential benefits and risks. The main therapeutic indication for PTC518 is Huntington's Disease, a genetic disorder that causes the progressive breakdown of nerve cells in the brain. At the molecular level, PTC518 works by reducing the levels of total huntingtin protein in the blood, which is believed to be involved in the disease's progression. It is classified pharmacologically as a small molecule therapeutic agent.

Investigated diseases

Huntington's Disease – Huntington's Disease is a genetic disorder that affects the brain, leading to the progressive breakdown of nerve cells. It typically manifests in adulthood and is characterized by a combination of movement disorders, cognitive decline, and psychiatric symptoms. Individuals with this condition may experience involuntary movements, such as jerking or writhing, as well as difficulties with coordination and balance. Cognitive symptoms can include problems with memory, attention, and decision-making. Psychiatric symptoms may involve depression, irritability, and mood swings. As the disease progresses, these symptoms tend to worsen, impacting daily functioning and quality of life.
Trial detailsLast updated 4 Oct 2026
Age18+ yearsPhasePhase IITrial ID2023-504628-24-00Protocol codeCHTT227A12201Estimated enrolment250 patientsSponsorNovartis Pharma AG

sourced from the EU Clinical Trials Register and site verification

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