A Phase II trial evaluating a novel therapy to treat Parkinson's disease dementia (PDD) is actively recruiting in the United States. The Michael J. Fox Foundation (MJFF) is funding the SYNAPSE trial, which is sponsored by Biotie Therapies, Inc. and conducted by the Parkinson Study Group.

Individuals with Parkinson's disease dementia experience symptoms of cognitive impairment, an umbrella term that includes slowness of thinking and difficulty with organizing one's thoughts, as well as memory loss and dementia.

The new compound in testing, SYN120, may address cognitive function by blocking the effects of serotonin, a chemical messenger in the brain that affects cognition. SYN120 is being tested in a 16-week proof of concept study ("SYN120 a Dual 5-HT6/5-HT2A Antagonist Proof of Concept Study to Evaluate Its Safety, Tolerability and Efficacy in Parkinson's Disease Dementia"), known as the SYNAPSE trial. The purpose of the study is to evaluate the safety, tolerability and efficacy of this compound in individuals with Parkinson's disease dementia. So far, the SYNAPSE trial has enrolled 47 participants across 20 sites, with a recruitment goal of 80 participants in total.

Chris Kenney, MD, senior vice president of clinical development, and Karen Cravotto, clinical program manager, at Biotie Therapies, Inc., spoke to MJFF about the trial and answered some questions about this new potential therapy.

MJFF: Congratulations on advancing this compound to Phase II testing. Can you tell us more about SYN120 and why it may be effective in treating Parkinson's disease dementia?

CK: Compounds that target the serotonin system have the potential to help patients with Parkinson's disease dementia. Based on preclinical evidence, we identified SYN120 as a promising compound and, with support from the Foundation, worked to advance this compound into clinical testing.

MJFF: What kinds of participants are you looking to enroll in this trial?

KC: We are looking to enroll individuals with Parkinson's disease dementia who are taking a stable cholinesterase inhibitor (for example, Exelon). Interested participants must also have a routine caregiver who can complete questionnaires and assist with transportation to site visits. Individuals with a history of any neurologic or psychiatric disease other than Parkinson's or any other condition or symptoms that would interfere with the trial (e.g., unpredictable motor fluctuations) will not be able to take part in the trial.

MJFF: Can you describe the type of participation required for this trial, and what the experience may be like?

KC: Those interested should expect a greater time commitment at the beginning of the trial. The baseline visit may take 6 to 9 hours; however, some sites allow participants to split the time across two days and will cover the cost of a hotel to reduce travel burden. After the screening and baseline visit, there will be a mix of phone (2) and on-site (3) visits, which will likely be less time-intensive. The last visit will occur two weeks after the end of the trial (at 18 weeks) to follow-up on drug safety.

MJFF: How will you evaluate the safety and efficacy of SYN120 in this trial?

CK: Participants will engage in computerized assessments of attention, working memory and decision-making skills to help determine the effect of this compound on cognition. We will evaluate safety and tolerability with a complete evaluation including blood tests and measures of heart activity. The first dose of SYN120 will be taken at the study site in order to monitor any immediate effects.

MJFF: Thanks for speaking with us. Is there anything else that you would like to add?

CK/KC: The study participant retention rate has been higher than we anticipated. Although there is a greater time commitment at the beginning of the trial, most participants have been able to attend all study visits and complete the trial.

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