Conference Coverage

Angelman syndrome treatment safe, well-tolerated, and effective in exploratory analyses



OV101 (gaboxadol), a type A gamma-aminobutyric acid receptor agonist, was safe, well tolerated, and improved clinical outcomes in a phase 2 trial of adults and adolescents with Angelman syndrome, according to results of a study presented at the annual meeting of the American Academy of Neurology.

Clinician-rated clinical global impressions of improvement (CGI-I) were improved versus placebo in the randomized study, as were other outcomes in post hoc analyses, including measures of sleep and motor function, said Alexander Kolevzon, MD, professor of psychiatry and pediatrics at the Icahn School of Medicine at Mount Sinai, New York.

This study of OV101 was a genetics-driven trial for the rare genetic disorder, which is caused by mutations in UBE3A and characterized by seizures, speech impairments, profound intellectual disability, gait problems, and anxiety, Dr. Kolevzon said in a press conference.

“The only treatments that exist are really very symptomatically driven,” Dr. Kolevzon said. “Here, we are taking a genetics-first approach. Having identified the gene, there is some understanding of what the underlying biology is, and it seems to relate to deficits in tonic inhibition.”

OV101 is a delta-selective type A gamma-aminobutyric acid receptor agonist that may potentially normalize the tonic inhibition that is decreased in Angelman syndrome. “What we think this compound is doing is actually reversing the deficits of tonic inhibition, and sort of restoring that state to these patients,” Dr. Kolevzon said in the press conference.

A total of 78 patients completed the phase 2, randomized study, known as STARS, which had a primary endpoint of safety and tolerability over 12 weeks of treatment with OV101 once daily, twice daily, or placebo. The mean age of the 87 patients who enrolled and had at least one dose of study drug was 22.6 years.

Most adverse events were mild, and frequencies of specific adverse events were similar for OV101 and placebo treatment groups, according to Dr. Kolevzon and his coinvestigators.

Improvements in motor function, sleep, and behavior were seen in a series of exploratory analyses, including global improvement at week 12, as captured by CGI-I, which was significantly improved for daily OV101 versus placebo (P = .0006).

These phase 2 results have informed discussions of which specific endpoints might be incorporated into the design of a planned phase 3 trial in pediatric patients. The CGI-I may be especially useful to measure clinical improvement in Angelman syndrome, which is a very “heterogeneous” disorder, Dr. Kolevzon said in the press conference.

“Every child has a different composite of symptoms, so that is the big challenge,” Dr. Kolevzon said. “I do not think we are going to have one singular outcome. The idea is to have a global measure that really captures heterogeneity across each trial and allows for children to be compared to their baseline, and each as their own control, in essence, but with specific domains in mind.”

Funding for the study came from Ovid Therapeutics. Dr. Kolevzon reported disclosures related to Ovid Therapeutics, as well as Coronis Neurosciences, 5AM Ventures, SEMA4, LabCorp, and AMO Pharma.

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