Efficacy and Safety of Safinamide in Parkinson's Disease Patients with Motor Fluctuations Without Levodopa Dosage Escalation over 18 Weeks: KEEP Study

This multicentre, prospective, single-arm study evaluated safinamide as add-on therapy to levodopa in Korean patients with Parkinson's disease (PD) with motor fluctuations with ≥ 1.5 h of "off" time daily, who took levodopa ≥ 3 times/day (n = 199). Baseline levodopa and dopamine agonist doses were maintained without escalation during the 18-week treatment period. Participants received safinamide 50 mg/day for 2 weeks and 100 mg/day thereafter. PD diaries and questionnaires (Parkinson's Disease Questionnaire, PDQ-39; Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale, MDS-UPDRS part 3 and part 4; King's Parkinson's Disease Pain Scale, KPPS; Mini-Mental State Examination, MMSE) were assessed at baseline and at week 18. Treatment-emergent adverse events (TEAEs) were recorded. Mean disease duration was 6.6 years, and mean levodopa equivalent daily dose was 721.1 mg/day. At week 18, significant improvements from baseline were seen for the co-primary endpoints, mean daily "off" time (- 1.3 ± 2.4 h, p < 0.001) and quality of life (QoL) based on PDQ-39 summary index (- 2.7 ± 10.3, p < 0.001), Moreover, significant improvements were seen in motor symptoms and motor complications (MDS-UPDRS part 3 and 4), daily "on" time without dyskinesia (all p < 0.001) and pain (KPPS; p = 0.013). TEAEs occurred in 40.2% of patients, with most being mild in severity. In conclusion, safinamide at a dosage of 100 mg/day significantly improved motor symptoms, QoL, and pain, and demonstrated a favourable safety profile without levodopa dosage escalation during the 18-week treatment period in Korean patients with PD.Trial registration number and date: NCT05312632, First Posted: April 5, 2022.