HONOLULU — The investigational dopamine-1 (D1) receptor antagonist ecopipam (developed by Emalex Biosciences) is safe and effective for the improvement of Tourette syndrome (TS) symptoms in children, adolescents, and adults, new research showed.
In a phase 3 withdrawal trial of more than 100 patients, the pediatric subgroup receiving ecopipam had a 50% risk reduction for relapse compared with those receiving placebo, meeting the primary endpoint.
There was also a 50% risk reduction for active treatment vs placebo in the full study population, which included both pediatric and adult patients.
The most common adverse events (AEs) in the ecopipam group during 24 weeks (the 12-week double-blind period plus a 12-week open-label period) included somnolence, anxiety, and headache. Importantly, the drug was not associated with weight gain.
Kinga Tomczak, MD, PhD
“As a clinician, I was excited to see that this was a positive study, with a side-effect profile that was pretty mild,” study investigator Kinga Tomczak, MD, PhD, pediatric neurologist and director of the Tic Disorders and Tourette Syndrome Program at Boston Children’s Hospital, Boston, told Medscape Medical News.
“I hope it will become another option for our patients. We haven’t had any new drugs for this disorder for a while,” added Tomczak, who is also an assistant professor of neurology at Harvard Medical School, Boston.
The study was presented on October 7 at the International Congress of Parkinson’s Disease and Movement Disorders (MDS) 2025.
First-In-Class Medication
Most of the approved therapies for TS act at D2 receptors and “are limited by the risk for weight gain, metabolic abnormalities, and drug-induced movement disorders,” the investigators wrote.
“Most of the treatments we currently have are far from ideal because they can cause other issues. So there is a big need for something that will help but also not have bad side effects,” Tomczak added.
Ecopipam is a potentially first-in-class medication that blocks neurotransmitter dopamine action at the D1 receptor.
“D1 receptor supersensitivity may be a mechanism for the repetitive and compulsive behaviors associated with Tourette syndrome,” the company noted in a press release announcing preliminary top-line results earlier this year. The FDA has granted ecopipam Orphan Drug and Fast Track designations for pediatric patients with TS.
As previously reported by Medscape Medical News, the investigators presented results from a phase 2b trial of ecopipam vs placebo in pediatric patients at last year’s MDS meeting.
In the current study, individuals older than 5 years and with TS entered into a 12-week open-label phase, during which they received only ecopipam. The medication was titrated up to a target dose of 1.8 mg/kg/d.
At the end of that period, those who experienced meaningful improvement — defined as at least a 25% reduction in the Yale Global Tic Severity Scale Total Tic Score (YGTSS-TTS) — went on to be randomly assigned to either continue receiving the target dose of ecopipam (n = 51; 73% male; 84% pediatric patients) or switched to placebo (n = 53; 66% male; 89% pediatric patients) during a 12-week double-blind period.
The primary endpoint was time from start of randomization to relapse (defined as at least a 50% decrease in the YGTSS-TTS improvement score from the open-label period) in the subgroup aged 6-17 years. Secondary endpoints included this same measure in the entire patient group and safety.
‘Durable Treatment Effect’
Results showed that pediatric members of the group who continued taking ecopipam had a significantly greater delay in time to relapse during the 12-week randomization period than their counterparts in the group who switched to placebo (hazard ratio [HR], 0.5; P = .008).
In the overall patient population, those receiving ecopipam also had a 50% risk reduction for relapse compared with those receiving placebo (HR, 0.5; P = .005).
These findings “support the maintenance and durability of the treatment effect,” Tomczak told meeting attendees.
Somnolence was the most frequent AE during the entire 24-week study period in those receiving the active treatment (11.1%), followed by anxiety or headache (9.7% for each), insomnia (8.8%), and tic worsening (7.9%).
There were no drug-induced movement disorder AEs attributed to the active treatment and “no signal of clinically relevant” metabolic AEs or weight gain.
“For extrapyramidal-related symptoms, we didn’t observe any in any patient,” Tomczak said.
Tomczak noted that her team is now conducting an extension trial including patients from both the phase 3 and phase 2B studies, with some participants having taken the drug for over a year. They plan to continue monitoring the patients for 2-3 years to assess any long-term effects.
A Promising and Better Option
Commenting for Medscape Medical News, David Shprecher, DO, a movement disorders neurologist with Banner Sun Health Research Institute in Sun City, Arizona, and co-director of the Arizona Center of Excellence for TS consortium between Banner Health and Phoenix Children’s Hospital, noted that the study had a novel design.
David Shprecher, DO
Shprecher said the treatment already established tolerability in the prior phase 2 study and showed “promising” efficacy for a short period. So the current trial sought to address longer-term efficacy.
“I think the study did that and really addressed the problem of placebo response in a novel way that we haven’t seen in recent trials. It’s more of a randomized withdrawal design,” he said.
Shprecher, who was not involved with the research and has TS himself, applauded the inclusion of adults in the study.
“I think that’s important. While the treated population in neurologic clinics around the world is more likely to be pediatric, there definitely are adults who have persistent tics that are more severe and a source of disability,” Shprecher said.
“So it’s important that we have information about how adults respond,” he added.
If approved in the future, Shprecher noted that the treatment could prove especially helpful for a specific group of patients.
“There’s an important niche here, with patients who we may be concerned about regarding metabolic side effects from antipsychotics, like weight gain or increased cholesterol,” he said.
But with this medication, “we’d have an option where we wouldn’t have to worry about those side effects. We really don’t have any antipsychotics we can comfortably say don’t have this risk,” Shprecher added.
The study was funded by Emalex Biosciences. Tomczak reported having served as a clinical trial site investigator for and receiving travel support from Emalex. She also received consulting fees from Emalex and Jazz Pharmaceuticals. Shprecher reported having been a member of the Data Safety Monitoring Board for the drug’s phase 2 trial.