A novel drug aimed at reducing brain inflammation has shown potential to slow the progression of Parkinson’s disease, according to early clinical trial results. The medication, known as SNT-4728, was tested on patients diagnosed with isolated REM sleep behaviour disorder (iRBD), a condition in which the normal paralysis during REM sleep is lost, leading sufferers to physically or vocally act out their dreams. Approximately 70% of individuals with iRBD are estimated to develop Parkinson’s or a related neurodegenerative disorder within 15 years.

The phase-2 trial involved 41 participants from the UK and Australia, with roughly three-quarters receiving daily doses of SNT-4728 and the remainder a placebo for three months. Brain imaging revealed that 20 of 30 patients on the drug experienced a reduction in inflammation within the putamen—a brain region associated with controlling movement and motor skills commonly affected by Parkinson’s symptoms such as stiffness, tremor, and slowness of movement. Researchers believe that inflammation in this area contributes to the damage and death of dopamine-producing nerve cells, which play a critical role in the disease’s progression.

SNT-4728 is designed to target harmful neuroinflammation without broadly suppressing the immune system. While current Parkinson’s treatments manage symptoms, none have been proven to slow or halt the underlying disease. The trial’s design focused on assessing changes in brain inflammation rather than directly measuring disease progression, meaning longer and larger studies will be necessary to determine if reducing inflammation can indeed delay or prevent Parkinson’s onset.

Experts involved in the study have described the findings as promising. Professor Simon Lewis, director of the Parkinson’s Disease Research Clinic at Macquarie University in Australia, noted that the statistically significant reduction in inflammation over a short period suggests the drug may affect disease-relevant pathways. Dr Lynsey Bilsland, managing director of Parkinson’s UK’s global drug development program—which funded the research—expressed optimism that targeting symptoms before they manifest could slow or even stop Parkinson’s progression. She emphasized that the results open avenues for further trials and underlined the importance of continued research and patient participation.

Some participants in the trial reported improvements beyond inflammation reduction. Marisa O’Connor, a 65-year-old from Coventry, said she experienced better balance, vision, and memory during the study, highlighting potential broader benefits of the treatment for both iRBD and Parkinson’s communities.

Full results from the trial are expected to be published later this year. With an estimated 166,000 people living with Parkinson’s in the UK alone, researchers stress the urgent need for therapies that go beyond symptom management to alter the course of the disease. The study represents a significant step toward that goal, with ongoing efforts to understand Parkinson’s causes and develop effective treatments continuing worldwide.