SEP-363856 is a psychotropic agent with a non-D2 mechanism of action.
Unlike existing antipsychotic drugs that bind to dopamine 2 (D2) or serotonin 2A (5-HT2A) receptors, the new agent is believed to stimulate trace amine-associated receptor 1 (TAAR1) and serotonin 1A (5-HT1A) receptors.
Sunovion and PsychoGenics jointly own the compound, while the former holds exclusive rights for worldwide development and commercialisation.
Sunovion president and CEO Antony Loebel said: “Schizophrenia is a major public health challenge associated with persistent abnormalities in thinking, perception and behaviour, as well as impairments in quality of life and functional skills, that affects approximately 2.4 million people in the US.
“Breakthrough therapy designation underscores the potential of SEP-363856 as a novel treatment for patients with schizophrenia, for whom few major advances in treatment have occurred since the advent of antipsychotic pharmacotherapy in the 1950s.”
The FDA breakthrough status is based on results from the pivotal Phase II clinical trial and a six-month, open-label, safety and tolerability extension study.
Called SEP 361-201, the randomised, placebo-controlled, double-blind, registration Phase II trial met its primary endpoint.
Results showed that patients with acute exacerbation of schizophrenia demonstrated statistically significant and clinically meaningful improvement in the positive and negative syndrome scale (PANSS) total score when treated with SEP-363856 compared to placebo at four weeks.
In addition, SEP-363856 was found to improve the overall severity of illness as measured using the clinical global impression scale-severity. Improvement was also observed in all major positive, negative and general psychopathology (PANSS) subscales.
During the study, the investigational drug was generally well-tolerated. Discontinuation rates were notably similar between the SEP-363856 and placebo arms.
Apart from schizophrenia, SEP-363856 is being developed for the treatment of Parkinson’s disease psychosis. The company is planning to expand its use to other indications.