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

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

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).