The Effects of Safinamide in Chinese and Non-Chinese Patients with Parkinson's Disease.

Introduction: Ethnicity differences are an important determinant in the clinical manifestation of Parkinson's disease (PD), but they are not yet widely recognized, particularly regarding the response to dopaminergic medications. The aim of this paper is to analyze the efficacy and safety of safinamide in Chinese patients with PD in the pivotal studies SETTLE and XINDI compared to the non-Chinese population of the SETTLE trial.

Methods: SETTLE (NCT00627640) and XINDI (NCT03881371) were phase III, randomized, double-blind, placebo-controlled, multicenter trials. Patients received safinamide or placebo as add-on to levodopa. The primary efficacy endpoint was the change in the mean total daily OFF time. Secondary efficacy endpoints included total daily ON time, ON time with no/non-troublesome dyskinesia, Unified Parkinson's Disease Rating Scale, and Parkinson's Disease Questionnaire-39 items. Safety was evaluated through the frequency of adverse events. Data from 440 non-Chinese and 109 Chinese patients in the SETTLE study, and 305 Chinese patients in the XINDI trial were considered for this post hoc analysis.

Results: Significant positive results were seen in favor of safinamide in all populations for the primary and secondary endpoints, with no differences in terms of magnitude. No "treatment by ethnicity" interaction was detected for any parameters, confirming the homogeneity of treatment effects between different populations. The safety and tolerability of safinamide in Chinese patients were similar to those in the other ethnic groups, without unexpected adverse reactions.

Conclusions: Safinamide was shown to improve PD symptoms and quality of life in different ethnic populations, without any treatment by race interaction. Further studies are warranted to investigate potential differences in a real-life situation.

Trial Registration Number: SETTLE (NCT00627640) and XINDI (NCT03881371).