Exenatide showed apparent improvement in MSA patient-reported symptoms, but all objective measures (brain scans, blood biomarkers, walking tests) showed no benefit — likely a placebo effect from the open-label design.
0 objective improvementsDespite a statistically significant improvement on the subjective UMSARS scale (p=0.0003), no objective measure — biomarkers, imaging, gait, or functional tests — showed any benefit from exenatide in MSA
What the researchers found
In 50 MSA patients, exenatide-treated participants showed less worsening on the clinician/patient-rated UMSARS scale (6.1 vs 13.3 points at 48 weeks, adjusted difference -7.4 points, p=0.0003) — a seemingly impressive result. However, none of the objective secondary measures showed significant differences: ambulation loss, falls, speech, swallowing, timed walking, cognition, neurofilament light chain, CSF alpha-synuclein oligomers, gait sensors, or brain imaging were all similar between groups.
The authors candidly conclude that the discrepancy between the positive subjective primary outcome and the negative objective measures is likely due to placebo effects and observer bias inherent to the open-label design.
Why it matters
This is a cautionary tale for GLP-1 drug repurposing in neurodegenerative diseases. While exenatide showed neuroprotective effects in animal models of MSA, this human trial found that the apparent clinical benefit disappeared when measured objectively. The finding highlights the critical importance of double-blind trial design when testing peptide drugs for neurological conditions where placebo effects are strong. It also tempers enthusiasm about GLP-1 drugs as a treatment for neurodegenerative diseases beyond Parkinson's.
The numbers in context
n=50 (25 per group) · 48-week treatment + 48-week washout · UMSARS difference -7.4 points (p=0.0003) · No significant objective differences · NfL, alpha-synuclein, gait, imaging all similar
How the study worked
Single-center, randomized, open-label trial. 50 MSA patients randomized 1:1 to exenatide 2 mg subcutaneous weekly for 48 weeks or control, followed by 48-week washout. Primary outcome: UMSARS parts I+II combined score at 48 weeks. Secondary outcomes included objective measures of ambulation, falls, speech, swallowing, timed walking, quality of life, cognition, biomarkers (NfL, CSF alpha-synuclein oligomers), sensor-derived gait, and brain imaging.
Who was studied
Adults with multiple system atrophy, 50 participants randomized equally to exenatide or control
What this study cannot tell us
The open-label design is the critical limitation — patients and clinicians knew who received exenatide, allowing placebo effects and observer bias to inflate the subjective primary outcome. The lack of any objective measure improvement strongly suggests the primary outcome benefit was not a true drug effect. The sample size (n=50) limits power for secondary outcomes. MSA is a rapidly progressive disease, making it difficult to detect neuroprotective effects over 48 weeks.
How to read the evidence
This is a randomized but open-label clinical trial. The discordance between positive subjective outcomes and negative objective outcomes, combined with the open-label design, strongly suggests the primary result was driven by placebo/observer bias. Published in Annals of Neurology, a top neurology journal.
When this study was published
Published in 2025, this is the first clinical trial of a GLP-1 agonist in MSA. Its negative objective findings are important for directing future neurodegenerative disease trials toward blinded designs.
The bigger picture
GLP-1 drugs are being investigated for multiple neurodegenerative diseases including Parkinson's, Alzheimer's, and MSA. While Parkinson's trials have shown more promising signals, this MSA trial is a sobering reminder that impressive-sounding results from unblinded trials can be entirely driven by placebo effects. It underscores the need for rigorous double-blind designs when testing peptide drugs for neurological conditions — and highlights that neuroprotection in animal models doesn't always translate to human benefit.
Questions still open
- Would a double-blind, placebo-controlled trial of exenatide in MSA show any objective benefit?
- Why did exenatide fail in MSA when it has shown more promising signals in Parkinson's disease trials?
- Are there specific MSA subtypes or disease stages where GLP-1 neuroprotection might still be relevant?
Common questions
What is multiple system atrophy?
Why does it matter that the trial was open-label?
Read the original research
Exenatide Once Weekly in the Treatment of Patients with Multiple System Atrophy.
Annals of neurology, 98(5), 991-1003
Citation
Vijiaratnam, Nirosen; Girges, Christine; Wiegand, Martin; Ismail, Claudia; Lameirinhas, Alexandra; Yarnall, Alison; Kirk, Cameron; Del-Din, Silvia; Rochester, Lynn; Kobylecki, Christopher; Ambler, Gareth; Skene, Simon; Houlden, Henry; Chelban, Viorica; Heslegrave, Amanda; Phillips, Wendy; Whone, Alan; Quinn, Niall; Lambert, Christian; Dore, Charlotte; Morris, Huw R; Horrocks, Mathew H; Lee, Ji Eun; O'Shaughnessy, Judi; Li, Yazhou; Greig, Nigel H; Gandhi, Sonia; Libri, Vincenzo; Athauda, Dilan; Foltynie, Tom. (2025). Exenatide Once Weekly in the Treatment of Patients with Multiple System Atrophy.. Annals of neurology, 98(5), 991-1003. https://doi.org/10.1002/ana.70004