Phase 3 Post Hoc Analysis Shows Foslevodopa/Foscarbidopa Reduces Troublesome Dyskinesia in Advanced Parkinson Disease

In a post hoc analysis of 2 phase 3 clinical trials, researchers evaluated whether treatment with foslevodopa/foscarbidopa (Vyalev; AbbVie) was associated with reductions in troublesome dyskinesia (TSD) in people with advanced Parkinson disease (PD). Across both a randomized controlled trial (RCT; NCT04380142) and an open-label extension study (OLT; NCT03781167), a large proportion of participants experienced elimination of TSD following treatment, regardless of the duration of their TSD at baseline.¹

At baseline, more than one-third of participants reported any TSD, including 27 of 74 participants (36.5%) in the RCT and 99 of 244 participants (40.6%) in the OLT. Among those with at least 1 hour of TSD at baseline, 22 of 74 participants (29.7%) in the RCT and 83 of 244 participants (34.0%) in the OLT met this threshold. In this subgroup, 8 of 22 participants (36.4%) in the RCT and 48 of 83 participants (57.8%) in the OLT had no TSD at the final visit.

This post hoc analysis, presented at the 2026 American Academy of Neurology (AAN) Annual Meeting, held April 18–22 in Chicago, Illinois, evaluated changes in TSD in individuals with advanced PD treated with foslevodopa/foscarbidopa across a 12-week, phase 3, double-blind, RCT, and a 52-week, phase 3, single-arm, OLT. Data from these prior studies supported the approval of foslevodopa/foscarbidopa for the treatment of motor fluctuations in advanced PD, demonstrating increased ON time without troublesome dyskinesia compared with oral immediate-release carbidopa/levodopa (CD/LD IR).²

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Presented by lead author Robert A. Hauser, MD, MBA, director of the Parkinson's and Movement Disorder Center at the University of South Florida, the analysis included participants aged 30 years or older who experienced at least 2.5 hours of daily OFF time at baseline. Motor states, including OFF time and ON time with and without dyskinesia, were recorded using Parkinson disease diaries. Final visit assessments were defined as the last available nonmissing postbaseline measurement.

Among participants with more than 1 hour of TSD at baseline, researchers noted that 12 of 74 participants (16.2%) in the RCT and 66 of 244 participants (27.0%) in the OLT were included in this subgroup. At the final visit, authors reported that 4 of 12 participants (33.3%) in the RCT and 40 of 66 participants (60.6%) in the OLT had no TSD.

Regarding safety, prior data from the phase 3 RCT published in The Lancet Neurology reported that foslevodopa/foscarbidopa had a generally favorable safety profile, with most adverse events (AEs) classified as mild or moderate in severity. Serious AEs occurred in 8% of participants in the foslevodopa/foscarbidopa group compared with 6% in the CD/LD group. One death was reported in the study and was considered a treatment-emergent AE in a participant receiving CD/LD.³

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REFERENCES
1. Hauser R, Antonini A, Di Luca DG, et al. Foslevodopa/Foscarbidopa Reduces Troublesome Dyskinesia in People with Advanced Parkinson’s Disease in Two Phase Three Clinical Trials. Presented at: 2026 AAN Annual Meeting; April 18-22; Chicago, Illinois.
2. U.S. FDA Approves VYALEV™ (foscarbidopa and foslevodopa) for Adults Living with Advanced Parkinson's Disease. News Release. AbbVie. Published October 17, 2024. Accessed April 21, 2026. https://news.abbvie.com/2024-10-17-U-S-FDA-Approves-VYALEV-TM-foscarbidopa-and-foslevodopa-for-Adults-Living-with-Advanced-Parkinsons-Disease
3. Soileau MJ, Aldred J, Budur K, et al. Safety and efficacy of continous subcutaneous foslevodopa-foscarbidopa in patients with advanced Parkinson’s disease: a randomized, double-blind, active-controlled, phase 3 trial. Lancet Neurol. 2022;21(12):1099-1109. doi:10.1016/S1474-4422(22)00400-8.