The Safety Profile of Pridopidine, a Novel Sigma-1 Receptor Agonist for the Treatment of Huntington's Disease.

Background: Huntington's disease (HD) is a rare, fatal, chronic progressive neurodegenerative disorder with a significant unmet medical need for effective treatments. Pridopidine is a novel, first-in-class, highly selective and potent sigma-1 receptor (S1R) agonist in development for HD. Pridopidine has been extensively studied in adult HD across the full spectrum of disease severity and age ranges, and its safety profile has been characterized in approximately 1600 participants across multiple studies and a broad range of doses. The specific objective of this study was to gain an in-depth understanding of pridopidine's safety profile at the recommended human dose of 45 mg twice daily (bid) in patients with HD.

Methods: An integrated safety analysis of pooled data from 1067 patients with HD enrolled in four double-blind, placebo-controlled studies was performed. The safety profile of pridopidine was compared with placebo.

Results: Pridopidine was found to be generally safe and well tolerated with an adverse event (AE) profile comparable to that of placebo. Moreover, there were no significant differences observed in the safety profile of pridopidine compared with placebo when analyzed by age, sex, baseline total functional capacity (TFC), cytosine-adenine-guanine (CAG) repeat length, use of antidopaminergic medications (ADMs), and region.

Conclusions: The integrated analysis replicated and corroborated the good safety profile observed in the individual studies. Despite the larger sample size, no new safety signals emerged. Long-term exposure to pridopidine, up to 6.5 years in open-label extension studies, revealed no new safety concerns, supporting its potential for long-term use in patients with HD.