The pipeline for Parkinson’s disease (PD) medications is extremely crowded these days, with multiple medications at various stages of research and development. Currently most of the approved medications for PD address the motor symptoms of PD – tremor, slowness, stiffness, and walking difficulties. Medications are also available to help people overcome OFF time or improve dyskinesias.
Clinical Trials for Non-Motor Symptoms of PD
One of the major unmet needs in PD treatment is therapies for non-motor symptoms (such as cognitive issues, psychosis, constipation and others) as these can have a significant effect on daily quality of life for both the person living with PD and their care partner. Therefore, it is particularly exciting to witness compounds being studied in clinical trials for these symptoms. Many of the currently active clinical trials for non-motor symptoms involve studying medications that are already approved for other diseases or uses, in hopes of determining if the medication also works for a particular symptom in the context of PD. Although these trials are crucial, this blog will focus on clinical trials of newly developed compounds aimed to specifically treat non-motor symptoms in PD.
If you are interested in getting involved in a clinical trial, Clinicaltrials.gov is a website that you should know about. It is a database of all clinical trials for all diseases worldwide. When a clinical trial is registered with the site, it is assigned a unique number called the National Clinical Trial (NCT) number. I will be referring to these numbers as I outline the clinical trials that are being conducted for newly developed compounds for non-motor symptoms of Parkinson’s disease so that you can learn more about them if you’re interested in participating in the trial.
Treating Non-Motor Symptoms of Parkinson’s Disease
Treatment of cognitive difficulties in PD is a major unmet need. There is only one medication approved for PD dementia, called rivastigmine, and its effects are mild. Research efforts are focused on trying to develop new therapies to improve this symptom.
SAGE-718 is an NMDA receptor positive allosteric modulator, a molecule that enhances the activity of the NMDA receptor. It is currently being studied in a Phase 2 open label trial (meaning that everyone receives the active compound and no one receives a placebo) for people with PD and mild cognitive impairment (NCT04476017). In order to be considered for the trial, participants must have a Montreal cognitive assessment (MoCA) of 20-25 (a range of scores meant to target people with mild cognitive impairment.)
This molecule has previously been tested in Phase I clinical trials, in both healthy people and people with Huntington’s disease (HD). Healthy people were given a molecule that blocks the NMDA receptor before administration of SAGE-718 or placebo. Those receiving SAGE-718 showed a statistically significant improvement of measures of working memory and complex problem solving. The molecule was also tested in six people with HD, a neurodegenerative condition that often results in dementia and although is very distinct from PD, does share some of its features. This study was open label (no placebo group). Participants