Efficacy and Safety of Ecopipam for Tourette Syndrome: A Phase 3 Randomized Clinical Trial.

Importance: Current Tourette syndrome (TS) pharmacotherapy is hindered by adverse effects and high discontinuation rates. Objective: To evaluate the safety and maintenance of effect of ecopipam, a selective dopamine D1 receptor antagonist, for up to 24 weeks for TS. Design, Setting, and Participants: This randomized clinical trial was a phase 3, double-blind, placebo-controlled, randomized withdrawal study conducted between January 31, 2023, and February 4, 2025. Participants were enrolled at 77 sites in 12 countries. Individuals 6 years and older with TS were eligible. Intervention: In the 12-week, open-label period, ecopipam was titrated over 3 to 4 weeks (target dose, 1.8 mg/kg per day). Responders (≥25% improvement in Yale Global Tic Severity Scale Total Tic Score [YGTSS-TTS] at weeks 8 and 12) were randomized to continue ecopipam or taper to placebo for the 12-week double-blind period. Main Outcomes and Measures: Time to relapse (≥50% loss of open-label period YGTSS-TTS improvement) in participants aged 6 to 18 years (primary) and adults (exploratory). Results: The trial enrolled 216 participants (n = 167 [77.3%] pediatric; 146 [67.6%] male and 70 [32.4%] female) to the open-label ecopipam period. Of these, 43 pediatric participants (mean [SD] age, 14.3 [5.5] years) and 8 adult participants were randomized to receive ecopipam; 47 pediatric (mean [SD] age, 14.0 [5.8] years) and 6 adult participants were randomized to receive placebo. Ecopipam significantly reduced the relapse risk vs placebo in pediatric participants (hazard ratio [HR], 0.47; 95% CI, 0.26-0.84; P = .008; n = 90). In adults, the effect was directionally similar (HR, 0.51; 95% CI, 0.11-2.30; P = .37; n = 14) but not significant. The most frequently reported adverse events with ecopipam (open-label and double-blind periods) were somnolence (n = 24 [11.1%]), anxiety (n = 21 [9.7%]), headache (n = 21 [9.7%]), insomnia (n = 19 [8.8%]), tic (n = 17 [7.9%]), and fatigue (n = 14 [6.5%]). Ecopipam did not have a clinically meaningful impact on weight, metabolic parameters, or psychiatric scale measures. Drug-induced movement disorders were not observed. Conclusions and Relevance: Ecopipam maintained clinically meaningful TS symptom improvements and was well tolerated for up to 24 weeks. Adverse events primarily affected the central nervous system. Trial Registration: ClinicalTrials.gov Identifier: NCT05615220.