Key Highlights

  • Participants on SNT-4728 showed a statistically significant difference in clinician-assessed motor signs (MDS-UPDRS Part III, p=0.021) versus placebo at Week 24.
  • The primary imaging endpoint, reported on 6 July 2026, showed a significant reduction in brain inflammation in the putamen (p=0.0145).
  • No marked changes were seen in other motor, cognitive or quality-of-life measures, and the study of 41 participants over 12 weeks was exploratory.

Syntara Limited (ASX:SNT), a clinical-stage Drug Development company, announced on 7 October 2026 additional results from its randomised, double-blind, placebo-controlled Phase 2 study of SNT-4728 in participants with isolated REM Sleep Behaviour Disorder (iRBD), a sleep disorder associated with a high risk of progression to Parkinson's disease and related conditions.

Study design

The study evaluated the safety, tolerability and exploratory efficacy of SNT-4728, described as a first-in-class neuro-targeted anti-inflammatory therapy, in 41 participants randomised 3 to 1 to SNT-4728 or placebo. Treatment lasted 12 weeks, with a further 12 weeks off treatment to Week 24. The study was funded by Parkinson's Research Ventures, and the principal investigators are Professor Simon Lewis in Sydney and Professor Michele Hu in Oxford.

Motor signs result

Clinician-assessed motor signs, measured by the MDS-UPDRS Part III, showed a progressive between-group difference at Weeks 12 and 24, statistically significant at Week 24 (p=0.021), 12 weeks after treatment ended. Participants on SNT-4728 showed slightly improved motor function after the 12-week treatment period, while those on placebo worsened, and at Week 24 the SNT-4728 group improved further while the placebo group continued to deteriorate. The company says the placebo deterioration matches the expected direction in this population from published studies.

Imaging result and safety

The previously reported primary imaging endpoint showed a statistically significant reduction in brain inflammation, measured by TSPO PET imaging, unilaterally in the putamen (p=0.0145), with 20 of 30 participants on active treatment, or 67%, recording a reduction from baseline. TSPO signal was also reduced in other motor and cognitive regions. The company reports no treatment-related serious adverse events and says all previously reported adverse events across treatment arms were mild or moderate.

What was not significant

No marked changes over time were observed in other MDS-UPDRS measures or in the MoCA, SF-36 and RBDQ questionnaires. A smartphone-based motor composite was directionally consistent with the clinician result but showed no statistically significant difference between groups. Syntara notes the assessments were exploratory, the study was small and the treatment period short, and that it was not designed to detect changes across all measures. Analysis of the digital endpoint data and biomarker data remains outstanding.

Presentation and next stage

The results were to be presented by Professor Lewis at the International Congress of Parkinson's Disease and Movement Disorders in Seoul. Syntara says the converging evidence supports further clinical development of SNT-4728 as a potential disease-modifying therapy in prodromal and early Parkinson's disease, but the release does not announce a next trial, its design, funding or timing.

Syntara's wider pipeline

Syntara's lead candidate is amsulostat for the bone marrow cancer myelofibrosis, which has FDA Fast Track Designation, Orphan Drug Designation and IND clearance, has completed a Phase 2a trial and has two Phase 1c/2 studies in myelodysplastic syndrome. It is also advancing SNT-9465 in a Phase 1a/b study in hypertrophic scars and SNT-6302 in keloid scars, and studies SNT-4728 with Parkinson's UK as a SSAO/MAO-B inhibitor for sleep disorders and to slow neurodegeneration.

Interpretation limits

The company describes the results as convergent exploratory evidence of biological activity. A p-value of 0.021 on one secondary endpoint, in a 41-participant study with a 3 to 1 randomisation, does not establish clinical benefit, and the company notes that the placebo group worsened as expected in this population. Pre-specified analysis plans for secondary endpoints are not described in the release.