AZA-PD was a phase 2 clinical trial of azathioprine – an immunosuppressant medication – to evaluate its safety and ability to lower neuroinflammation in people with Parkinson’s.
About the study
Dr Caroline Williams-Gray at the University of Cambridge led a phase 2 clinical trial of azathioprine (AZA-PD) – an immunosuppressive drug currently used to treat autoimmune conditions, such as rheumatoid arthritis. This trial involved 66 people with early-stage Parkinson’s (diagnosed <3 years before recruitment) taking azathioprine or a placebo (dummy drug) for 12 months. The researchers aimed to evaluate if azathioprine can “correct” the Parkinson’s immune profile and slow progression of the condition by suppressing immune activity in the brain and body. They also compared the immune profiles of participants with age-matched controls to get a better idea of how this differs in people with Parkinson’s.
Cure Parkinson’s funded a sub-study of this trial, which aimed to better understand azathioprine’s mechanism of action (MoA), or what a drug interacts with in the body to achieve the desired effect. To do so, the researchers used brain imaging, alongside analyses of blood and cerebrospinal fluid (CSF; the fluids surrounding the brain and spinal cord) samples to determine whether azathioprine lowered immune activity. Samples were collected at the initial, 12-month, and 18-month follow-up visits.
This study concluded in early 2025 and we are currently waiting on the publication of the results.
Trial overview
- Researcher: Dr Caroline Williams-Gray
- Institution: University of Cambridge
- Project Type: Clinical Trial, Phase 2
- Status: Completed; Awaiting publication
- Dates: February 2020 – February 2025 (delayed due to COVID-19)
- iLCT-evaluated (2017)
- Therapy Target: Neuroinflammation
More about the study
What is azathioprine?
Azathioprine is an immunosuppressant, meaning it lowers activity of the immune system. There is growing evidence to support that neuroinflammation, or inflammation in the brain, may be a driver of Parkinson’s progression. Inflammation is one of the body’s natural immune responses; however, chronic, or long-term, inflammation can lead to damage of normal cells.
Studies have suggested that the immune system may be over-active in people with Parkinson’s, meaning neuroinflammation could be contributing to the loss of dopamine nerve cells (neurons) experienced in Parkinson’s. Therefore, researchers are now interested in therapies, like azathioprine, which may be able to lower neuroinflammation, and their potential to slow Parkinson’s progression.
Video presentation – Dr Caroline Williams-Gray discusses the trial
A sub-study of azathioprine in Parkinson’s
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