An Extension Study to Evaluate the Long-Term Safety and Efficacy of PTC518 in Participants With Huntington's Disease (HD)

PTC Therapeutics

Status and phase: Invitation-only; Phase 2

Conditions: Huntington Disease

Treatments: Drug: PTC518

Study type: Interventional

Funder types: Industry

Identifiers

NCT06254482

PTC518-CNS-004-HD

2023-504628-24-00 (Other Identifier)

Details and patient eligibility

About

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

Full 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 30 additional months.

All participants will receive active PTC518 in this extension study. Participants who received PTC518 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, or 20 milligrams [mg]). Participants who received placebo in the parent Study PTC518-CNS-002-HD will be allocated to a PTC518 dose level according to the same dosing group in which they were previously randomized (5, 10, or 20 mg). The 20 mg dosing arm will be open for randomization only if and when the Data Safety and Monitoring Board from the parent Study PTC518-CNS-002-HD recommends initiating this dosing level based on an unblinded review of safety data from that study.

Enrollment: 250 estimated patients

Sex: All

Ages: 25+ years old

Volunteers: No 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 exclusion criteria may apply.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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250 participants in 3 patient groups

PTC518 5 mg

Experimental group

Description:

Participants will receive PTC518 5 mg tablets once daily orally for 24 months.

Treatment:

Drug: PTC518

PTC518 10 mg

Experimental group

Description:

Participants will receive PTC518 10 mg tablets once daily orally for 24 months.

Treatment:

Drug: PTC518

PTC518 20 mg

Experimental group

Description:

Participants will receive PTC518 20 mg tablets once daily orally for 24 months.

Treatment:

Drug: PTC518