SEP-363856 is a candidate therapy being developed by Sunovion to treat schizophrenia, and the hallucinations and delusions linked to Parkinson’s disease. It is designed to act as an antipsychotic agent, but through a mechanism distinct from currently available antipsychotics. Specifically, it does not bind to dopamine 2 (D2) or serotonin 2A (5-HT2A) receptors, as current antipsychotics are thought to do.
The 21-week, multi-part Phase 2 SEP361-203 trial (NCT0299369) is expected to enroll up to 36 patients, ages 55 and older, at 24 sites. Among them, 24 people will initially be randomized to SEP-363856 treatment and 12 will be given a placebo.
Eligible patients must have been diagnosed at least one year before study’s start, and have been experiencing such psychosis symptoms as visual hallucinations or paranoia (delusions). Participants also need to have a caregiver able to attend an estimated 13 on-site visits.
Following an initial screening, patients will be randomly assigned to either SEP-363856 oral capsules at 25, 50, or 75 mg once daily, or to a matching placebo, for six weeks. This treatment period will be followed by 12 weeks of an open-label extension phase, during which all participants will be given SEP-363856.
Researchers will evaluate the safety, tolerability, and effectiveness of the candidate therapy.
They will assess changes in the Scale for Assessment of Positive Symptoms–Parkinson’s Disease (SAPS-PD) total score, which addresses manifestations of hallucinations and delusions. Researchers will also evaluate, as secondary trial goals, disease severity and patients’ cognitive function.
The roughly five-month study is expected to expected to conclude in May 2020.
SEP-363856 was designated a breakthrough therapy as a potential treatment of schizophrenia by the U.S. Food and Drug Administration in May, based largely on results from a Phase 2 trial and an open-label extension study. The designation offers FDA guidance to the company in developing the potential treatment, and priority review should a request be filed for approval.
More information on the SEP361-203 study is available on its website.