An Extension Study to Evaluate the Long-Term Safety and Efficacy of Votoplam in Participants With Huntington's Disease (HD)

A Phase 2b, Double-Blind, Randomized Extension Study to Evaluate the Long-Term Safety and Efficacy of Votoplam in Participants With Huntington's Disease

Status

Active, not recruiting

Phases

Phase 2

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT06254482

Enrollment

144

Registered

2024-02-12

Start date

2023-08-25

Completion date

2029-07-16

Last updated

2025-11-21

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Huntington Disease

Keywords

Neurodegenerative disorder, Rare disease

Brief summary

The primary goal of this study is to evaluate the long-term safety and pharmacodynamic effects of votoplam in participants with HD.

Detailed description

Participants who completed the Treatment Period in the parent Phase 2a Study PTC518-CNS-002-HD (NCT05358717), fulfilled the enrollment criteria, and chose to enroll in this extension study will undergo baseline evaluations and be assessed for 54 additional months. All participants will receive active votoplam in this extension study. Participants who received votoplam in the parent Study PTC518-CNS-002-HD will continue at the same dose level they received in that study in a blinded fashion (5, 10 milligrams \[mg\]). Participants who received placebo in the parent Study PTC518-CNS-002-HD will be allocated to a votoplam dose level according to the same dosing group in which they were previously randomized (5, 10 mg).

Interventions

DRUGVotoplam

Votoplam will be administered per dose and schedule specified in the arm.

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

ALL

Age

25 Years to No maximum

Healthy volunteers

Inclusion criteria

* Participant who has completed the Treatment Period in Study PTC518-CNS-002-HD.

Exclusion criteria

* Participants who have not previously completed the Treatment Period in Study PTC518-CNS-002-HD. Note: Other inclusion and

Design outcomes

Primary

Measure	Time frame
Number of Participants With Treatment-emergent Adverse Events (TEAEs)	Baseline up to Month 54
Blood Total Huntingtin Protein (tHTT) Levels	Baseline up to Month 52

Secondary

Measure	Time frame
Change From Baseline in Caudate Volume as Assessed Via Volumetric Magnetic Resonance Imaging (vMRI) at Month 48	Baseline, Month 48
Change From Baseline in Composite Unified Huntington's Disease Rating Scale (cUHDRS) Scores at Month 48	Baseline, Month 48
Cerebrospinal Fluid (CSF) Mutant Huntingtin Protein (mHTT) Levels	Baseline up to Month 48
Blood mHTT Protein Levels	Baseline up to Month 52

Countries

Australia, Austria, Canada, France, Germany, Italy, Netherlands, New Zealand, Spain, United Kingdom

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026