Category: Parkinson’s Disease: Clinical Trials
Objective: We report motor function, motor complication and tolerability findings of the EPSILON study up to 1.5 years.
Background: The 24-week, double-blind, placebo-controlled Phase III EPSILON study (NCT04978597) [ref 1] demonstrated that the addition of opicapone in non-fluctuating levodopa-treated patients with Parkinson’s disease (PD) significantly improved motor impairment without increasing the likelihood of developing motor complications versus placebo.
Method: Participants who completed the 24-week, double-blind phase received opicapone 50 mg during the 52-week open-label extension study. Results for participants who switched from placebo to opicapone were compared with those who received opicapone throughout the two phases (1.5 years). Changes in the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Part III (motor score) and Part IV were key endpoints. Safety was evaluated across 1.5 years.
Results: The efficacy of opicapone on motor symptoms during the double-blind phase was sustained during the 1-year open-label phase (adjusted mean MDS-UPDRS Part III score ± standard error (SE) change from double-blind baseline to Week 76: -7.4±0.81). Patients who switched from placebo to opicapone had a reduction of their MDS-UPDRS Part III mean score ± SE from double-blind baseline to Week 76 of -6.1±0.79 [figure1]. At Week 76, 80.2% of patients in the opicapone-opicapone group remained free of motor complications compared with 69.7% in the placebo-opicapone group (p=0.1) [figure2a]. At study end, there were no significant differences between the opicapone-opicapone and placebo-opicapone groups in the percentage of patients remaining free of motor fluctuations (84.2% vs. 79.3%), dyskinesias (92% vs. 85.8%,) or dystonia (95.1% vs. 95.7%) [figure2b-d]. Opicapone was well-tolerated.
Conclusion: Opicapone provided sustained symptomatic relief over 1.5 years in levodopa-treated patients without motor fluctuations and was not associated with an increased risk for motor complications.
Figure 1
Figure 2
References: 1. Ferreira JJ, et al. Eur J Neurol. 2025 Jan;32(1):e16420.
To cite this abstract in AMA style:
J. Ferreira, O. Rascol, F. Stocchi, A. Antonini, H. Brigas, J. Moreira, JF. Rocha, M. Fonseca, J. Holenz, W. Poewe. Long-Term Effect of Opicapone in Parkinson’s Patients Without Motor Complications: 1.5-year EPSILON Study Findings [abstract]. Mov Disord. 2025; 40 (suppl 1). https://www.mdsabstracts.org/abstract/long-term-effect-of-opicapone-in-parkinsons-patients-without-motor-complications-1-5-year-epsilon-study-findings/. Accessed October 5, 2025.« Back to 2025 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/long-term-effect-of-opicapone-in-parkinsons-patients-without-motor-complications-1-5-year-epsilon-study-findings/