An investigational drug reduced motor and phonic tics in children and adolescents with Tourette syndrome, according to findings of a phase 2b trial presented at the International Congress of Parkinson's Disease and Movement Disorders.
Unlike currently approved treatments such as haloperidol and pimozide, which are dopamine D-2 receptor antagonists, ecopipam is a first-in-class dopamine D-1 receptor antagonist. Researchers hope the new drug will be as effective as older drugs in reducing tics while also avoiding such side effects as tardive dyskinesia.
As previously reported at the AAN Annual Meeting in April, ecopipam had a significant effect from baseline to week 12 on the Yale Global Tic Severity Score—Total Tic Score (YGTSS-TTS), with a mean difference of -3.4 (p=0.011).
The latest presentation also included results on other more subjective measures. The mean change from baseline to week 12 on the Clinical Global Impression of Tourette Syndrome Severity (CGI-TS-S) score was significant (p=0.001), as was the YGTSS global score (p=0.004).
The updated findings also suggested a significant effect on the Caregiver Global Impression of Change scale (p<0.05). There was no significant effect, however, on the QoL scale (p=0.978).
Paragon Biosciences LLC, which funded the study and is developing the drug, is planning a phase 3 trial of the drug
The trial will be twice as long as the phase 2b trial and will befollowed by a two-year open label extension. The phase 2b trial has a one-year open label extension, which is still underway, said the first author of the abstract, Atul Mahableshwarkar, MD, chief medical officer of Emalex Biosciences, the Paragon company developing ecopipam.
The study of 149 participants (74 on ecopipam and 75 on placebo) began with a four-week titration period, an eight-week maintenance period, and a one-week tapering period. Treatment-related adverse events occurred in 34 percent of patients on ecopipam and in 21 percent on placebo. The most common side effects on ecopipam were headache (9.2 percent), insomnia (5.3 percent), fatigue (6.6 percent), somnolence (6.6 percent), and restlessness (5.3 percent). No weight gain or other metabolic adverse events occurred with ecopipam.
A neurologist who specializes in movement disorders said the current study was not long enough and the sample size too small to assess the drug's potential efficacy as a long-term treatment for Tourette syndrome.
“The findings are promising, but the trial was small, and the eight-week time period is not sufficient to determine whether there is sustained benefit," said Melissa Nirenberg, MD, PhD, FAAN, professor of neurology at the Icahn School of Medicine at Mount Sinai, who was not involved with the study.
“The high rate of short-term side effects may also limit the utility of this drug in clinical practice," Dr. Nirenberg said, “though it is unclear how this compares with the side effect profile of established treatments."
She said additional clinical trials are warranted, “ideally with a study design that includes not only a placebo group but also an active comparison group of subjects treated with dopamine D-2 receptor antagonists."
Dr. Mahableshwarkar is a salaried employee of Emalex Biosciences. Dr. Nirenberg had no disclosures.