An Extension Study to a Clinical Study That Will Continue to Evaluate the Effectiveness and Safety of SEP-363856 in People With Schizophrenia That Switch to SEP-363856 From Their From Their Current Antipsychotic Medication

An Open-label Extension Study to Assess the Safety and Tolerability of SEP-363856 in Subjects With Schizophrenia Switched From Typical or Atypical Antipsychotic Agents

An Extension study to a clinical study that will continue to evaluate the effectiveness and safety of SEP-363856 in people with schizophrenia that switch to SEP-363856 from their current antipsychotic medication. This study will accept both male and female participants that have completed study SEP361-308. This study will be held in approximately 24 study sites in North America. Participation in the study will be approximately up to 25 weeks.

Study Overview

• Status: Completed
• Conditions: Schizophrenia
• Intervention / Treatment: Drug: SEP-363856

Detailed Description

This is a 24-week, outpatient, multicenter, flexible-dose, open-label extension study designed to evaluate the long-term safety and tolerability of SEP-363856 (50 to 100 mg/day) for the treatment of subjects with schizophrenia who have completed Study SEP361-308 treatment period, during which they were switched from a previous antipsychotic treatment to SEP-363856.

• Study Type: Interventional
• Enrollment (Actual): 75
• Phase: Phase 3

Contacts and Locations

Study Locations

• United States
  • California
    • Anaheim, California, United States, 92805
      • Research Site
    • Bellflower, California, United States, 90706
      • Research Site
    • Garden Grove, California, United States, 92845
      • Research Site
    • Lemon Grove, California, United States, 91945
      • Research Site
    • Santee, California, United States, 92071
      • Research Site
    • Torrance, California, United States, 90502
      • Research Site
  • Florida
    • Hollywood, Florida, United States, 33021
      • Research Site
    • Miami, Florida, United States, 33122
      • Research Site
  • Georgia
    • Atlanta, Georgia, United States, 30318
      • Research Site
    • Atlanta, Georgia, United States, 30331
      • Research Site
  • Illinois
    • Chicago, Illinois, United States, 60640
      • Research Site
  • Maryland
    • Gaithersburg, Maryland, United States, 20877
      • Research Site
  • New Jersey
    • Berlin, New Jersey, United States, 08009
      • Research Site
  • North Carolina
    • Charlotte, North Carolina, United States, 28211
      • Research Site
    • Hickory, North Carolina, United States, 28601
      • Research Site
  • Texas
    • Richardson, Texas, United States, 75080
      • Research Site

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria: (list is not all inclusive)

• Subject has given written informed consent and privacy authorization prior to participation in the study.
• Subject has completed the Treatment Period of Study SEP361-308.
• Subject has not taken any psychotropic medication other than the study drug, pre-switch antipsychotic and protocol-allowed medications during Study SEP361-308.
• Female subject must have a negative rapid urine pregnancy test at the End of Treatment (EOT) Visit of Study SEP361-308.

Exclusion Criteria: (list is not all inclusive)

• Subject is suicidal based on the Columbia - Suicide Severity Rating Scale (C-SSRS) assessment at the End of Treatment (EOT) Visit of Study SEP361-308.
• Subject has a clinically significant abnormality including physical examination, vital signs, or ECG finding at the End of Treatment (EOT) Visit of Study SEP361-308.
• Subject has a positive rapid urine drug screen at the EOT Visit of Study SEP361-308.
• Female subject is pregnant or lactating.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: SEP-363856	Drug: SEP-363856; SEP-363856 tablet

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With Adverse Events (AEs)	An AE is any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease occurring after the administration of a medicinal (investigational) product, whether or not considered related to the medicinal (investigational) product.	From first dose of study drug up to end of 1 week follow up period (up to Week 25)
Number of Participants With Serious Adverse Events	An AE is any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease occurring after the administration of a medicinal (investigational) product, whether or not considered related to the medicinal (investigational) product. A serious adverse event is any AE occurring at any dose that results in death, is life-threatening, results in persistent or significant disability/incapacity, requires in-patient hospitalization or prolongation of existing hospitalization, or is a congenital anomaly/birth defect.	From first dose of study drug up to end of 1 week follow up period (up to Week 25)
Number of Participants With AEs Leading to Discontinuation of Study	An AE is any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease occurring after the administration of a medicinal (investigational) product, whether or not considered related to the medicinal (investigational) product. AEs leading to discontinuation from the study are those AEs which caused participant to discontinue from the study.	From first dose of study drug up to end of 1 week follow up period (up to Week 25)

Collaborators and Investigators

• Sponsor: Otsuka Pharmaceutical Development & Commercialization, Inc.
• Investigators: Study Chair: CNS Medical Director, Sumitomo Pharma America, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): March 31, 2023
• Primary Completion (Actual): September 23, 2024
• Study Completion (Actual): September 23, 2024

Study Registration Dates

• First Submitted: February 13, 2023
• First Submitted That Met QC Criteria: February 13, 2023
• First Posted (Actual): February 23, 2023

Study Record Updates

• Last Update Posted (Actual): December 11, 2025
• Last Update Submitted That Met QC Criteria: November 24, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: Schizophrenia
• Additional Relevant MeSH Terms: Schizophrenia Spectrum and Other Psychotic Disorders; Mental Disorders; Schizophrenia; SEP-363856
• Other Study ID Numbers: SEP361-309

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

Anonymized Individual participant data (IPD) that underlie the results of this study will be shared with researchers to achieve aims pre-specified in a methodologically sound research proposal. Small studies with less than 25 participants are excluded from data sharing.

Access is provided after a research proposal is submitted and has received approval from the Independent Review Panel and after a Data Sharing Agreement is in place. Access is provided for an initial period of 12 months but an extension can be granted, when justified, for up to another 12 months.

• IPD Sharing Time Frame: Data will be available after marketing approval in global markets, or beginning 1-3 years following article publication. There is no end date to the availability of the data.
• IPD Sharing Access Criteria: Otsuka will share data on the Vivli data sharing platform which can be found here: https://vivli.org/ourmember/Otsuka/
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No