for people ages 25 years and up (full criteria)
at La Jolla, California and other locations
study started
completion around



The primary goal of this study is to evaluate the safety and pharmacodynamic effects of PTC518 compared with placebo in participants with HD.

Official Title

A Phase 2A, Randomized, Placebo-Controlled, Dose-Ranging Study to Evaluate the Safety and Efficacy of PTC518 in Subjects With Huntington's Disease


Participants will first be randomized to Part A or Part B or Parts D or E in a 1:1 randomization ratio, depending on their Huntington's disease Integrated Staging System (HD-ISS) staging criteria and then to active treatment (PTC518 5 mg in Parts A and D and 10 mg in Parts B and E) or matching placebo within each part in a 2:1 ratio of active treatment to placebo. A Drug Safety Monitoring Board (DSMB) Charter will undertake an unblinded review of safety data from the 5 and 10 mg dosing groups and provide a recommendation on when Parts C and F (with a 20 mg active treatment arm) can be initiated. At that time, participants will be randomized to any study Part that is currently open for enrollment, and then to either active treatment or placebo (in a 2:1 ratio) within that Part.


Huntington Disease, Neurodegenerative disorder, Rare disease, PTC518, PTC518 5 mg, PTC518 10 mg, PTC518 20 mg


You can join if…

Open to people ages 25 years and up

  • Genetically confirmed HD diagnosis with a cytosine-adenine-guanine (CAG) repeat length from 40 to 50, inclusive

    Eligibility for HD-ISS Stage 2 Group (Parts A, B, and C):

  • A Unified Huntington's Disease Rating Scale (UHDRS)-Independence Scale (IS) score of 100
  • A UHDRS Total Functional Capacity (TFC) score of 13
  • A score between 0.18 and 4.93 inclusive on the normed version of the HD prognostic index (PINHD)

    Eligibility for HD-ISS Mild Stage 3 Group (Parts D, E, and F):

  • A UHDRS Total Functional Capacity (TFC) score of 11 or 12, or a UHDRS TFC score of 13 with an UHDRS IS score of <100

You CAN'T join if...

  • Receipt of an experimental agent within 90 days or 5 half-lives prior to Screening or anytime over the duration of this study, ribonucleic acid (RNA)- or deoxyribonucleic acid (DNA)-targeted HD-specific investigational agents such as antisense oligonucleotides, cell transplantation, or any other experimental brain surgery
  • Any history of gene therapy exposure for the treatment of HD
  • Participation in an investigational study or investigational paradigm (such as exercise/physical activity, cognitive therapy, brain stimulation, etc) within 90 days prior to Screening or anytime over the duration of this study
  • Any medical history of brain or spinal disease that would interfere with the lumbar puncture process safety assessments
  • Any medical history or condition that would interfere with the ability to complete the protocol-specified assessments (for example, implanted shunt, conditions precluding magnetic resonance imaging [MRI] scans)
  • Pregnancy, planning on becoming pregnant during the course of the study or within 6 months of end of treatment, or currently breastfeeding

    Note: Other inclusion and exclusion criteria may apply.


  • University of California, San Diego in progress, not accepting new patients
    La Jolla California 92037 United States
  • Rocky Mountain Movement Disorders Center not yet accepting patients
    Englewood Colorado 80113 United States
  • The Ottawa Hospital, Parkinson's and Movement Disorders Clinic accepting new patients
    Ottawa K1Y 4E9 Canada
  • The Barbery National Centre for Mental Health accepting new patients
    Birmingham B15 2FG United Kingdom
  • Cardiff University Schools of Medicine and Biosciences accepting new patients
    Cardiff CF10 3AX United Kingdom
  • The Leeds Teaching Hospitals NHS Trust, Chapel Allerton Hospital withdrawn
    Leeds LS7 4SA United Kingdom
  • UCL Queen Square Institute of Neurology National Hospital for Neurology and Neurosurgery accepting new patients
    London WC1N 3BG United Kingdom
  • Manchester University NHS Foundation Trust accepting new patients
    Manchester M13 9WL United Kingdom


accepting new patients at some sites,
but this study is not currently recruiting here
Start Date
Completion Date
PTC Therapeutics
Phase 2 Huntington's Disease Research Study
Study Type
Expecting 252 study participants
Last Updated