A Trial of the Efficacy and Safety of SEP-363856 in Acutely Psychotic Participants With Schizophrenia

Key Inclusion Criteria:

Male or female participants between 18 to 65 years of age (inclusive) at the time of consent.

Participant is experiencing an acute exacerbation or relapse of symptoms, with onset (≤) 2 months prior to screening

1. The participant requires hospitalization for this acute exacerbation or relapse ofsymptoms.

2. If already an inpatient at screening, has been hospitalized for less than 2 weeksfor the current exacerbation at the time of screening.

Participants who are experiencing an acute exacerbation of psychotic symptoms and marked deterioration of usual function as demonstrated by meeting ALL of the following criteria at the screening and baseline visits:

1. Participant must have a PANSS total score ≥ 80, AND a PANSS item score ≥ 4, moderateor greater, for ≥ 2 of the following Positive Scale (P) items: i. Item 1 (P1;delusions) ii. Item 2 (P2; conceptual disorganization) iii. Item 3 (P3;hallucinatory behavior) iv. Item 6 (P6; suspiciousness/persecution); AND

2. Participant must have a CGI-S score ≥ 4.

Participants who have received previous outpatient antipsychotic treatment at an adequate dose (minimal recommended dose for the treatment of schizophrenia according to the manufacturer labeling) for an adequate duration (at least 6 weeks) and who showed a previous good response to such antipsychotic treatment (other than clozapine) in the last 12 months, according to the investigator's opinion.

Key Exclusion Criteria:

Sexually active participants or persons of childbearing potential (POCBP) who do not agree to practice 2 different clinical trial sponsor approved methods of birth control or remain abstinent during the course of the trial and for 30 days after the last dose of study drug.

Participant has had a decrease (improvement of symptoms) of ≥ 20% on the PANSS total score between screening and baseline.

Participant has a current DSM-5 diagnosis or presence of symptoms consistent with a DSM-5 diagnosis other than schizophrenia. Exclusionary disorders include, but are not limited to, alcohol use disorder (within past 12 months), substance (other than nicotine or caffeine) use disorder within past 12 months, major depressive disorder, bipolar I or II disorder, schizoaffective disorder, obsessive compulsive disorder, and posttraumatic stress disorder. Symptoms of mild to moderate mood dysphoria or anxiety are allowed so long as these symptoms are not the primary focus of treatment.

Participant has had psychiatric hospitalization(s) for more than 30 days (cumulative) during the 90 days prior to screening.